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DEPARTMENT OF NATURAL RESOURCES AND ENVIRONMENTAL CONTROL
Division of Water
Surface Water Discharges Section
Statutory Authority: 7 Delaware Code, Chapter 60 (7 Del.C., Ch. 60)
7 DE Admin. Code 7101
 
proposed
 
REGISTER NOTICE
SAN #2008-29
 
1. Title Of The Regulations:
Regulations Governing the Design, Installation and Operation of On-Site Wastewater Treatment and Disposal Systems
 
2. Brief Synopsis Of The Subject, Substance And Issues:
Substantial revisions to the Regulations Governing the Design, Installation and Operation of On-Site Wastewater Treatment and Disposal Systems (On-site regulations) are proposed to incorporate the Guidance and Regulations Governing the Land Treatment of Wastes spray irrigation regulatory language. The on-site regulations have been revised to address large system site investigations, hydrogeological investigations, design considerations, operation and maintenance practices, updating of individual on-site wastewater treatment and disposal system design criteria, establishment of new licensees and inspection protocols, and to establish performance standards for small on-site systems utilizing alternative technologies and all large systems.
 
3. Possible Terms Of The Agency Action:
There is no sunset date for this regulation.
 
4. Statutory Basis Or Legal Authority To Act:
Title 7, Delaware Code, Chapter 60, Environmental Control
 
5. Other Regulations That May Be Affected By The Proposal:
Upon the effective date of revised regulations, the Regulations Governing the Pollution Control Strategy for the Indian River, Indian River Bay, Rehoboth Bay, and Little Assawoman Bay Watersheds, effective November 11, 2008, Sections 6.0, 7.0 and 8.0, may be affected.
 
6. Notice Of Public Comment:
The proposed revisions to the Regulations Governing the Design, Installation and Operation of On-Site Wastewater Treatment and Disposal Systems were initially published in this Register on April 1, 2012. The Department of Natural Resources and Environmental Control (DNREC) Division of Water then held a public hearing on these proposed revisions on May 3, 2012, at 6:00 p.m. in the DNREC Auditorium, Richardson and Robbins Building, 89 Kings Highway, Dover, DE 19901, to address the proposed changes that have occurred over the past three years as a result of discussions, public workshops, committee meetings and literature searches.
Subsequent to the public hearing held on May 3, 2012, DNREC made additional revisions to the Regulations Governing the Design, Installation and Operation of On-Site Wastewater Treatment and Disposal Systems, in order to thoroughly address the comments and concerns received to date in this matter. Accordingly, DNREC will now re-open the record in this matter for an additional thirty (30) days, beginning on Monday, October 1, 2012, through close of business on Tuesday, October 30, 2012, in order to vet these revisions to the public, and to enable DNREC to receive additional public comment on the aforementioned revisions to the Regulations Governing the Design, Installation and Operation of On-Site Wastewater Treatment and Disposal Systems. Following the close of the record on October 30, 2012, the Secretary will review the entire record developed throughout this promulgation, and will issue his Order setting forth his final decision in this matter shortly thereafter.
The proposed regulation revisions may be inspected at the following locations:
Department of Natural Resources and Environmental Control
89 Kings Highway
Dover, DE 19901
 
Department of Natural Resources and Environmental Control
20653 DuPont Blvd, Unit 5
Georgetown, DE 19947
 
The proposed regulation revisions may be inspected on the DNREC Division of Water, Groundwater Discharges Section website:
http://www.wr.dnrec.delaware.gov/Information/GWDInfo/Pages/GWDS%20Design%20Install%20Operate%20Info%20For%20Proposed%20Wastewater%20Treatment%20Regulations.aspx
 
For additional information or any appointments to inspect the proposed regulation revisions at DNREC, please contact Jack Hayes, DNREC Division of Water, Groundwater Discharges Section, 89 Kings Highway, Dover, DE 19901, (302) 739-9948, John.Hayes@state.de.us.
Interested parties shall submit written statements and comments in writing on the proposed regulation revisions, beginning October 1, 2012, but no later than close of business on October 30, 2012, as designated herein, addressed to:
 
Jack Hayes
DNREC - Division of Water
Groundwater Discharges Section
89 Kings Highway
Dover, DE 19901
 
7. Prepared By:
Jack Hayes / (302) 739-9948, September 19, 2012, John.Hayes@state.de.us
 
7101 Regulations Governing the Design, Installation and Operation of On-Site Wastewater Treatment and Disposal Systems
 
FOREWORD
 
The Department of Natural Resources and Environmental Control (the Department) finds that a substantial portion of the State’s population lives where centralized water supplies or wastewater treatment services are limited. It is the intent of the Department to aid and assist the public in the installation of on-site wastewater treatment and disposal systems, where possible, by utilizing the best information, techniques and soil evaluations for the most suitable system that site and soil conditions permit.
Statewide Regulations Governing the Design, Installation and Operation of On-Site Wastewater Treatment and Disposal Systems have existed since 1968. Inappropriate installations and poor operation and maintenance practices have resulted in disposal system malfunctions. Inadequately renovated wastewater has contaminated the State’s groundwater and presented a threat to the public health, safety, and welfare. Corrective measures required the replacement of water supply and wastewater systems, sometimes at a very high cost which is sometimes borne by the general public. After years of working under the Regulations which were first implemented in the 1960’s, numerous deficiencies were found to be present within the same. Given this, the Department concluded that significant revisions to its Regulations.
In considering these findings, the Department determined that the adoption of effective Regulations was the proper course of action. Through a process that included considerable staff research, public meetings and presentations, public workshops, a public hearing and a hearing officer’s report along with four draft versions of these Regulations were prepared, reviewed and revised. This final version is the result of those various activities, and incorporates, as best as possible, all valid concerns into its provisions.
The purpose of these Regulations, is to prevent the problems listed above. They are based on the best information available and include the establishment of a process for updating Regulations as information changes. They include what are considered to be the best engineered design standards for on-site systems, as determined by research and practical experience. These Regulations seek to require the use of on-site systems that will function according to their performance criteria without causing the State’s ground water resources to violate U. S. Environmental Protection Agency Drinking Water Standards on an average annual basis. Wastewater management actions necessary to achieve those standards were recommended to the Department in Delaware’s 1983 Comprehensive Committee’s Final Report which has since been adopted as state policy.
The proper siting of systems is addressed by the establishment of various soil criteria which lead to the selection of the most suitable on-site wastewater treatment and disposal system for local conditions. System selection and sizing are determined using the results of the site specific soil evaluations and percolation tests. Density is addressed by the adoption of minimum lot sizes tied to appropriate treatment and disposal techniques, and in some cases, the use of scientific ground water and geological analyses that both assure renovation of degradable pollutants and dilution of wastes which are inadequately treated in the soil. Site evaluation and system selection, design, installation and pump-outs are required to be performed by individuals licensed under these Regulations. Alternative system design criteria were established to enable proper waste treatment and disposal to occur in locations where conventional systems would be inappropriate. With the advent of mortgage companies requiring wastewater system inspections prior to loan approval, the Department took a pro-active approach to create a new licensee category (Class H System Inspector) and standardized format to perform the inspection so all inspections will be evaluated under the set of criterion. Finally, a specific variance procedure is established to provide an opportunity to reconsider any provision of these Regulations, provided that proper public disclosure and adequate consideration of the consequences are provided.
In developing these Regulations, the Department operated under the philosophy that where soil and site conditions permit, the least complex, easy to maintain and most economical system should be used. Although it has not been possible to include directly every method of on-site treatment and disposal, the Department’s policy is to encourage development of systems, processes and techniques which may benefit significant numbers of people within Delaware. It is expected that these Regulations will be reviewed and revised periodically and that standards for other alternative systems will be prepared as more experience and research data become available. The Regulations contain provisions that enable that process to occur.
 
1.0 Authority and Scope
1.1 These Regulations are adopted by the Secretary of the Department of Natural Resources and Environmental Control under and pursuant to the authority set forth in 7 Del.C., Ch. 60.
1.2 These Regulations shall apply to all aspects of:
1.2.1 The planning, design, construction, operation, maintenance, rehabilitation, replacement, inspection and modification of individual and community on‑site wastewater treatment and disposal systems within the boundaries of the State of Delaware; and
1.2.2 The planning, design, construction and operation and maintenance of on‑site wastewater holding tanks within the boundaries of the State of Delaware; and
1.2.3 The licensing of percolation testers, on‑site wastewater treatment and disposal system designers, soil scientists, on‑site wastewater treatment and disposal system contractors, system inspectors and liquid waste haulers within the boundaries of the State of Delaware.
1.3 These Regulations shall supersede and replace Water Pollution Control Regulations #2 Governing The Installation and Operation of Septic Tank Sewage Disposal Systems, the Guidelines for Septic Tank Systems, and Part II of Section 9 of the Regulations Governing the Control of Water Pollution. With respect to the other provisions of the Regulations Governing the Control of Water Pollution these Regulations shall supersede such Regulations only to the extent of any inconsistency. These Regulations shall apply throughout the State of Delaware.
1.4 The Department has the authority to establish and collect fees for the defraying of expenses incurred by the Department for facilities and services needed to provide for the administration of its programs. The authority is contained within Amendments 4701(a), 6026(a), 7 Del.C., Ch. 60, which also contains the schedule of fees.
 
2.0 Definitions
2.1 Words and Phrases
The following words and phrases, when used in these Regulations have the meaning ascribed to them as follows, unless the text clearly indicates otherwise:
“Absorption Facility”: System of open‑jointed or perforated piping, alternative distribution units, or other seepage systems for receiving the flow from septic tanks or other treatment facilities and designed to distribute effluent for oxidation and absorption by the soil within the zone of aeration.
“Aggregate-free Chambers”: A buried structure used to create an enclosed unobstructed soil bottom absorption area and side-wall absorption area for infiltration and treatment of wastewater which can be use to replace the filter aggregate and distribution pipe in an absorption facility.
“Alteration”: Any physical change in the design capacity of an existing system or any part thereof.
“Alternating System”: Two or more disposal fields, equal in size with dosing provided alternatively to each field.
“Alternative Treatment and Disposal System”: A wastewater treatment or disposal system not specified in these Regulations which has been proven to provide at least an equivalent level of treatment as the conventional systems included in these Regulations.
“Applicant”: The owner or legally authorized agent of the owner as evidenced by sufficient written documentation.
“Authorization to Use Existing System Permit”: A written document issued by the Department which states that an on‑site wastewater treatment and disposal system appears adequate to serve the purpose for which a particular application is made.
“Aquifer”: A part of a formation, a formation, or a group of formations that contains sufficient saturated permeable material to yield economically useful quantities of water to wells or springs.
“Backfill”: Soil which is clean and free of foreign debris, placed over the disposal area and fill extensions.
“Blackwater”: Waste carried off by toilets, urinals, and kitchen drains.
“Building Sewer”: Piping which carries wastewater from a building to the first component of the treatment and disposal system.
“Cesspool”: A covered pit with a porous lining into which wastewater is discharged and allowed to seep or leach into the surrounding soils with or without an absorption facility.
“Commercial Facility”: Any structure or building, or any portion therefore, other than a residential dwelling.
“Community System”: An on‑site wastewater treatment and disposal system which will serve more than three (3) lots or parcels or more than three (3) condominium units or more than three (3) units of a planned unit development.
“Completed Application”: One in which the application form is properly completed in full, is signed by the applicant, is accompanied by all required exhibits, detailed plans and specifications, and required fee.
“Confined Aquifer”: An aquifer bounded above and below by impermeable beds or by beds of distinctly lower permeability than that of the aquifer itself and containing ground water. An aquifer containing ground water which is at a pressure greater than atmospheric pressure and from which water in a well will rise to a level above the top of the aquifer.
“Confining Layer”: A body of impermeable or distinctly less permeable material stratigraphically adjacent to one or more aquifers.
“Construction Permit”: A permit issued by the Department for the construction, alteration, repair or replacement of an on‑site wastewater treatment and disposal system.
”Construction Report”: A report prepared by the Class E Systme Contractor and submitted to the Department within 10 calendar days after the absorption facility has been completely installed.
“Conventional On-Site Wastewater Treatment and Disposal Systems”: Gravity, low pressure pipe, pressure-dosed, sand-lined and elevated sand mound.
“Department: The Department of Natural Resources and Environmental Control of the State of Delaware (DNREC).
“Developer”: A person, persons, partnership, firm, corporation, or cooperative enterprise undertaking or participating in the development of a subdivision, manufactured home community, or multi‑unit housing project.
“Director”: The Director of the Division of Water Resources for the State of Delaware or his/her authorized representative.
“Disposal Area”: The entire area used for the absorption facility.
“Distribution Box”: A box for distributing wastewater equally to separate distribution laterals of the absorption facility.
“Distribution System”: Piping or other devices used in the distribution of wastewater within the absorption facility. (Also referred to as distribution laterals)
“Dosing”: The pumped or regulated flow of wastewater to the absorption facility.
“Dosing Chamber”: A receptacle for retaining wastewater until pumped or regulated to the absorption facility.
“Down Gradient”: An area that has a lower potentiometric surface (hydraulic head) than a comparative reference point.
“Dwelling”: Any structure or building, or any portion thereof which is used, intended, or designed to be occupied for human living purposes including but not limited to, houses, houseboats, boathouses, mobile homes, manufactured homes, travel trailers, hotels, motels, apartments, and condominiums.
“Easement”: An interest in land owned by another that entitles its holder to a specific limited use or enjoyment.
“Effluent Filter”: A device placed in the outlet compartment of a septic tank which conforms to ANSI/NSF Standard 46 for the purpose of removing particulate matter before the effluent enters the absorption facility.
“Effluent Line”: The pipe beginning at the treatment unit or septic tank and terminating at the absorption facility.
“Elevated Sand Mound”: An on-site wastewater treatment and disposal system which maintains a 36 inch separation distance above the limiting zone which is pressurized into suitable fill material constructed above existing grade.
“Emergency Repair”: Repair of a broken system component where immediate action is necessary to protect public health.
“Escarpment”: Any naturally occurring slope greater than thirty (30) percent which extends vertically six (6) feet or more as measured from toe to top, and which is characterized by a long cliff or steep slope which separates two (2) or more comparatively level or gently sloping surfaces, and may intercept one (1) or more layers than limit soil depth.
“Existing On‑Site Wastewater Treatment and Disposal System”: Any installed on‑site wastewater treatment and disposal system constructed in conformance with the rules, laws and local ordinances in effect at the time of construction, or which would have conformed satisfactorily with system design provided for in Department Regulations.
“Feasibility Study”: A site/soil investigative report identifying the suitability of a parcel of land for on-site wastewater treatment and disposal systems. The report includes information pertinent to the Department and other local government agencies in the determination of certain land use decisions.
“Fill”: Soil material which has been transported to and placed over the original soil or bedrock and is characterized by a lack of distinct horizons or color patterns as found in naturally developed, undisturbed soils.
“Filter Aggregate”: Washed gravel or crushed stone ranging in size from 3/4" to 2 l/2" in any dimension and clean and free of fine materials (dust) or meeting grading specifications in §6.4.2.
“Filter Fabric”: Any material approved by the Department which is permeable but does not allow soil particles to pass through for the purpose of protecting the filter aggregate or aggregate free chambers within the absorption facility.
“Full Depth Gravity”: A gravity fed on-site wastewater treatment and disposal system which maintains a 36 inch separation distance above the limiting zone where the trench or bed is installed 24 inches into the natural soil.
“Governmental Unit”: The state or any county, municipality, or any part thereof.
“GPD”: Gallons per day.
“Grade”: The inclination or slope of a conduit or ground or plane surface.
“Gravity Capping Fill”: A gravity fed on-site wastewater treatment and disposal system which maintains 36 inches separation distance above the limiting zone where the trench or bed is installed between 12 and 23 inches into the natural soil below a soil cap of a specified depth and texture.
“Greywater”: The untreated wastewater that has not come into contact with toilet waste. Greywater includes wastewater from bathtubs, showers, bathroom wash basins, clothes washing machines, laundry tubs and other wastewater which does not present a threat from contamination by unhealthy processing, manufacturing or operating wastes. It does not include wastewater from kitchen sinks or dishwashers.
“Grease Trap”: A watertight tank for the collection and retention of grease that is accessible for periodic removal.
“Groundwater”: Any water naturally found under the surface of the earth.
“Holding Tank”: A watertight receptacle used to store wastewater prior to being removed by a licensed Class F Liquid Waste Hauler.
“Hydraulic Conductivity”: A specific mathematical coefficient (quantitative) that relates the rate of water movement to the hydraulic gradient. A term of Darcy’s law Q = KAi where K represents hydraulic conductivity and is the current standard for measuring a soils ability to transmit water.
“Impervious Strata and Formation”: An underground or surface layer of soil or rock which will not allow water to pass through it at a rate permissible for subsurface disposal and having a percolation rate slower than one hundred twenty (120) minutes per inch.
“Invert”: The floor, bottom or lowest portion of the internal cross section of a closed conduit or structure.
“Isolation Distance”: The horizontal distance between a system component and selected site features or structures.
“Large System”: Any on‑site wastewater treatment and disposal system with a projected wastewater design flow rate greater than two thousand five hundred (2,500) gallons per day.
“Lift Pump Station”: A receptacle for pumping wastewater to a system component to overcome slope differentials for the use of gravity distribution.
“Limiting Zone”: Any horizon or condition in the soil profile or underlying strata which includes:
“Lot: A portion of a subdivision or parcel of land.
“Low Pressure Pipe Capping Fill”: A pressurized on-site wastewater treatment and disposal system which is installed as trenches and maintains 18 inch separation distance above the limiting zone. The trenches are installed between 9-17 inches into natural soil below a soil cap of a specified depth and texture.
“Low Pressure Pipe Full Depth”: A pressurized on-site wastewater treatment and disposal system which is installed as trenches and maintains 18 inch separation distance above the limiting zone. The trenches are installed 18 inches into natural soil.
“Malfunctioning System”: A system which is not adequately renovating or hydraulically eliminating the wastewater it is receiving as evidenced by, but not limited to, the following conditions:
“Manifold”: A pipe with numerous branches to convey effluent between a large pipe and several smaller pipes, or to permit choice of diverting flow from one of several sources or to one of several discharge points.
“Manufactured Home”: A home built entirely in the factory under a federal building code administered by the Department of Housing and Urban Development (HUD). Manufactured homes may be single or multi-section and are transported to the site and installed.
“Mineral Soil”: A soil that is saturated with water less than 30 days (cumulative) per year in normal years and contains less than 20 percent (by weight) organic carbon; or is saturated for greater than 30 days or more cumulative in normal years, and has an organic carbon content (by weight) of less than 18 percent if the mineral fraction contains 60 percent or more clay; or less than 12 percent if the mineral fraction contains no clay.
“Monitor Well”: A well installed for the sole purpose of the determination of subsurface conditions and collecting groundwater samples.
“Mottling: Soil irregularly marked with spots of different colors that vary in number and size which may indicate poor aeration, lack of drainage and the upper extent of the seasonal high water table.
“Observation well”: A well used for the sole purpose of determining groundwater levels.
“On‑Site Wastewater Treatment and Disposal System”: Conventional or alternative, wastewater treatment and disposal systems installed or proposed to be installed on land of the owner or on other land to which the owner has the legal right to install the system.
“On-Site System Advisory Board (OSSAB)”: A panel of licensee’s representing the on-site industry, asked to serve by the Secretary, on all matters pertaining to the issuance and revocation of all on-site licenses.
“Owner”: The person who has a vested legal or equitable title to real or personal property, including an on‑site wastewater treatment and disposal system.
“Percolation rate”: The rate of water movement through a soil. Percolation rate is usually measured and assigned on the basis of elapsed time per unit volumetric water level drop. The most commonly used unit for expressing percolation rate is minutes per inch (mpi).
“Permeability”: The property of a soil horizon that enables the soil to transmit gases, liquid, or other substances.
“Permit”: The written document approved by the Department which authorizes the installation of an on-site wastewater treatment and disposal system or any part thereof, which may also require operation and maintenance of the system.
“Permittee”: Any individual, partnership, corporation, association, institution, cooperative enterprise, agency, municipality, commission, political subdivision or duly established entity to which a permit is issued.
“Piezometer”: A small diameter non-pumping well with a short screen that is used to measure the elevation of the water table or potentiometric surface.
“Platy Structure”: Soil aggregates that are developed predominantly along the horizontal axes, laminated and flaky.
“Pollution or Water Pollution”: Any alteration of the physical, chemical or biological properties of any waters of the state, including change in temperature, taste, color, turbidity, silt or odor of the waters, or such discharge of any liquid, gaseous, solid, radioactive or other substance into any waters of the state, which will or tends to, either by itself or in connection with any other substance, create a public nuisance or which will or tends to render such waters harmful, detrimental or injurious to public health, safety or welfare, or to domestic, commercial, industrial, agricultural, recreational or other legitimate beneficial uses or to livestock, wildlife, fish or other aquatic life or the habitat thereof.
“Potentiometric Surface”: A surface that represents the level to which water will rise in tightly cased wells.
“Pressure Dosed Capping Fill”: A pressurized on-site wastewater treatment and disposal system which maintains a 36 inch separation distance above the limiting zone where the trench or bed is installed between 12 and 23 inches into the natural soil below a soil cap of a specified depth and texture.
“Pressure Dosed Full Depth”: A pressurized on-site wastewater treatment and disposal system which maintains a 36 inch separation distance above the limiting zone where the trench or bed is installed 24 inches into the natural soil.
“Pressurized Distribution”: A network of piping with orifices designed to evenly distribute wastewater under pressure through the entire absorption facility.
“Primary Treatment”: A wastewater treatment process that takes place in a tank and allows those substances in wastewater that readily settle or float to be separated from the water being treated.
“Professional Engineer”: A person registered by the Delaware Association of Professional Engineers to practice professional engineering in the State of Delaware.
“Professional Geologist”: A person registered by the Delaware State Board of Registration of Geologists to practice professional geology in the State of Delaware.
“Project Site”: The total area within the property lines of an individual lot or within the division lines of a parcel or subdivision.
“Public Health Hazard”: A condition whereby there are sufficient types and amounts of biological, chemical or physical, including radiological, agents relating to water or sewage which are likely to cause human illness, disorders or disability. These include, but are not limited to, pathogens, viruses, bacteria, parasites, toxic chemicals, and radioactive isotopes.
“Redoximorphic Features”: Characteristic soil patterns formed by the reduction, translocation and oxidation of iron and manganese oxides. The occurrence of these features may be indicative of poor drainage, or lack of aeration associated with the upper most extent of the seasonal high water table.
“Repair”: Any modification to an existing on-site wastewater treatment and disposal system necessary to fix a problem or malfunction.
“Replacement System”: An on-site wastewater treatment and disposal system to replace the existing on-site wastewater treatment and disposal system or a portion thereof.
“Sand”: Individual mineral particles in a soil that range in diameter from the upper limit of silt (0.05 millimeters) to 2.0 millimeters.
“Sand Lined System”: A type of seepage trench or seepage bed soil absorption facility constructed in sandy fill material below the natural soil surface and may require pressurization. The fill material is used to replace a natural impermeable or slowly permeable soil layer or to completely remove an existing absorption facility.
“Sandy Fill”: Materials that consist of medium sand, sandy loam, loamy sand/sandy loam mixtures (see sieve requirements in §6.4.1).
“Scarifying”: Scraping or loosening the bottom and sidewall soil surfaces in the preparation of percolation test holes, seepage trenches, beds, or similar excavations.
“Scum”: A mass of sewage solids floating at the surface of effluent and buoyed up by entrained gas, grease or other substances.
“Seasonal High Water Table”: The highest zone of soil or rock that is seasonally or permanently saturated by a perched or shallow water table. A planar surface below which all pores in rock or soil (whether primary or secondary) is seasonally or permanently saturated.
“Secondary Treatment”: A combination of unit processes that will consistently remove 85% or more of the organic and suspended material in domestic wastewater and produce an effluent of sufficient quality to satisfy the following requirements; monthly average effluent BOD5 and TSS concentrations of 30 mg/L; daily maximum effluent BOD5 and TSS concentrations of 45 mg/L.
“Secretary”: Secretary of the Department of Natural Resources and Environmental Control or a duly authorized designee.
“Seepage Bed”: An absorption facility consisting of an area from which the entire earth contents have been removed and replaced with a network of perforated pipe, filter aggregate or aggregate-free chambers and covered with suitable backfill material.
“Seepage Pit”: A covered pit with a porous lining into which wastewater is discharged and allowed to seep or leach into the surrounding soil and is preceded by a septic tank.
“Seepage Trench”: A soil absorption facility consisting of ditches with vertical sides and flat bottoms partially filled with filter aggregate and containing perforated pipe or aggregate-free chambers and covered with suitable backfill material.
“Septage”: The liquid and solid contents of a septic tank.
“Septic Tank”: A watertight receptacle which receives the discharge of wastewater from a structure or part thereof and is designed and constructed so as to permit settling of solids from the liquid, digestion of the organic matter by detention, and discharge of the liquid portion into an absorption facility.
“Single Family Dwelling”: A residence intended for single family residential use.
“Siphon”: A hydraulically operated device designed to rapidly discharge the contents of a dosing tank between predetermined hydraulic levels.
“Site Evaluation”: The practice of investigating, evaluating and reporting basic soil and site conditions which apply to the on‑site wastewater treatment and disposal system type and design criteria.
“Slope”: Deviation of a plane surface from the horizontal. It is usually expressed as a ratio or percentage of number of units of vertical rise or fall per unit of horizontal distance.
“Soil Horizon: A layer of soil or soil material approximately parallel to the land surface and differing from adjacent genetically related layers in physical, chemical, and biological properties or characteristics such as color, structure, texture, consistence and pH.
“Soil Profile”: A vertical cross-section of a soil that shows the various soil horizons. Soil drainage or moisture status are soil characteristics that can be inferred from the soil profile.
“Soil Structure”: The combination or arrangement of primary soil particles into secondary compound particles or clusters, the principle forms of which are: platy (laminated); prismatic (prisms with rounded tops); blocky (angular or subangular); granular and columnar.
“Soil Texture”: The grain sizes that comprise a soil consisting of three textural classes; sand, silt and clay. Field methods for judging the texture of a soil consist of forming a cast of soil, both dry and moist, in the hand and pressing a ball of moist soil between thumb and finger.
“Sand”: Individual grains can be seen and felt readily. Squeezed in the hand when dry, this soil will fall apart when the pressure is released. Squeezed when moist, it will form a cast that will hold its shape when the pressure is released, but will crumble when touched.
“Sandy Loam”: Consists largely of sand, but has enough silt and clay present to give it a small amount of stability. Individual sand grains can be readily seen and felt. Squeezed in the hand when dry, this soil will readily fall apart when the pressure is released. Squeezed when moist, it forms a cast that will not only hold its shape when the pressure is released, but will withstand careful handling without breaking. The stability of the moist cast differentiates this soil from sand.
“Loam”: Consists of an even mixture of sand and of silt and a small amount of clay. It is easily crumbled when dry and has a slightly gritty yet fairly smooth feel. It is slightly plastic. Squeezed when moist, it forms a cast that will not only hold its shape when the pressure is released, but will withstand careful handling without breaking. The stability of the moist cast differentiates this soil from sand.
“Silt Loam”: Consists of a moderate amount of fine grades of sand, a small amount of clay, and a large quantity of silt particles. Lumps in a dry, undisturbed state appear quite cloddy, but they can be pulverized readily; the soil then feels soft and floury. When wet, silt loam runs together in puddles. Either dry or moist, casts can be handled freely without breaking. When a ball of moist soil is pressed between thumb and finger, it will not press out into a smooth, unbroken ribbon, but will have a ribbon appearance.
Clay Loam”: Consists of an even mixture of sand, silt, and clay, which breaks into clods or lumps when dry. When a ball of moist soil is pressed between the thumb and finger, it will form a thin ribbon that will readily break, barely sustaining its own weight. The moist soil is plastic and will form a cast that will withstand considerable handling.
“Silty Clay Loam”: Consists of a moderate amount of clay, a large amount of silt, and a small amount of sand. It breaks into moderately hard clods or lumps when dry. When moist, a thin ribbon or one‑eighth (1/8) inch wire can be formed between thumb and finger that will sustain its weight and will withstand gentle movement.
“Silty Clay”: Consists of even amounts of silt and clay and very small amounts of sand. It breaks into hard clods or lumps when dry. When moist, a thin ribbon or one‑eighth (1/8) inch or less sized wire formed between thumb and finger withstand considerable movement and deformation.
“Clay”: Consists of large amounts of clay and moderate to small amounts of sand. It breaks into very hard clods or lumps when dry. When moist, a thin, long ribbon or one‑sixteenth (1/l6) inch wire can be molded with ease. Fingerprints will show on the soil, and a dull to bright polish is made on the soil by a shovel.
“Silt”: Consists largely of silt with very small amounts of clay. The soil feels very silky or floury. When pressed between thumb and finger, it will readily pulverize without forming a ribbon.
“Loamy Sand”: Is predominately composed of sand, but has enough clay so that it can be formed into a weakly developed ball with careful handling.
Sandy Clay Loam”: The predominant particle size found within this soil textural class is sand, although it contains relatively high levels of clay with lesser amounts of silt. When moist, it will form a thin ribbon that does not readily break.
“Sandy Clay”: Consists of relatively even amounts of sand and clay with very small amounts of silt. When moist, a thin ribbon can readily be formed between thumb and finger without considerable deformation or movement.
“Solum”: The upper part of the soil profile (A, E and B horizons) above the parent material in which the processes of soil formation are active.
“Spare Area”: An area set aside for construction of a second absorption facility to be used in the event the original absorption facility malfunctions or is expanded.
“Subdivision”: Any tract or parcel of land which has been divided into two or more lots for which development is intended.
“System”: Refers to an on‑site wastewater treatment and disposal system.
“System Inspector”: A person licensed by the Department to inspect, investigate, collect data and make determinations regarding the present operational condition of an on-site wastewater treatment and disposal system.
“Test Pit”: An excavation used to examine a soil profile in order to assess soil permeability and depth to a seasonal high water table using soil texture, structure, and redoximorphic features as a basis for assessing site suitability.
“Topography”: Ground surface variations or contours of the earth's surface, both natural and anthropogenic.
“Unconfined Aquifer”: An aquifer in which no relatively impermeable layer exists between the water table and the ground surface and an aquifer in which the water is at atmospheric pressure.
“Undisturbed Soil”: Soil or soil profile unaltered by filling, removal, or other man‑made changes with the exception of agricultural activities.
“Upgradient”: An area that has a higher potentiometric surface (hydraulic head) than a comparative reference point.
“Wastewater”: Water‑carried waste from septic tanks, water closets, residences, buildings, industrial establishments, or other places, together with such groundwater infiltration, subsurface water, and mixtures of industrial wastes or other wastes as may be present.
“Wastewater Utility”: Any person who engages in the business of providing wastewater disposal and related services to the public for a fee, charge, or other remuneration in the State of Delaware.
“Watercourse”: Any ocean, bay, lake, pond, stream, river or defined ditch that will permit drainage into any surface water body, excluding ephemeral watercourses as defined below.
“Ephemeral”: A watercourse which flows briefly, only in direct response to precipitation in the immediate vicinity, and whose invert is above the seasonal high water table.
“Water Table”: The surface of an unconfined aquifer where the groundwater pore water pressure is equal to atmospheric pressure.
“Waters of the State”: Public waters, including lakes, bays, sounds, ponds, impounding reservoirs, springs, wells, rivers, streams, creeks, estuaries, marshes, inlets, canals, the ocean within the territorial limits of the State, and all other bodies of surface or underground water, natural or artificial, inland or coastal, fresh or salt, within the jurisdiction of the State of Delaware.
“Well”: Any excavation that is drilled, cored, bored, washed, driven, dug, jetted, or otherwise constructed when the intended use of such excavation is for the location, testing, acquisition, use; for extracting water from or for the artificial recharge of subsurface fluids; and where the depth is greater than the diameter or width. For the purpose of this regulation this definition does not include geotechnical test, soil, telephone and construction piling borings, fence posts, test pits, or horizontal closed loop heat pump circulation systems constructed within twenty (20) feet of the ground surface.
“Zone of Aeration”: A subsurface zone containing water under pressure less than that of the atmosphere, including water held by capillary and containing air or gases generally under atmospheric pressure. This zone is limited above by the land surface and below by the surface of the zone of saturation, i.e., the water table.
 
3.0 General Standards, Prohibitions and Provisions
3.1 Each and every owner of real property is jointly and severally responsible for:
3.1.1 Disposing of wastewater in conformance with all applicable Regulations; and
3.1.2 Connecting all plumbing fixtures on that property, from which wastewater is or may be discharged, to a central wastewater system or on‑site wastewater treatment and disposal system approved by the Department; and
3.1.3 Maintaining, repairing, and/or replacing the system as necessary to assure proper operation of the system
3.2 No person shall construct, install, modify, rehabilitate, or replace an on‑site wastewater treatment and disposal system or construct or place any dwelling, building, mobile home, manufactured home or other structure capable of discharging wastewater on‑site unless such person has a valid Class E System Contractor license and permit issued by the Department pursuant to these Regulations.
3.3 No permit may be issued by the Department under these Regulations unless the county or municipality having land use jurisdiction has first approved the activity through zoning procedures provided by law.
3.4 Any county may assume responsibility and authority for administering its own regulatory program for on‑site wastewater treatment and disposal systems pursuant to 7 Del.C. Ch. 60, §6003(d), if the delegated program establishes standards no less stringent than the standards established in these Regulations.
3.5 Administrative and judicial review and the enforcement under these Regulations shall be in accordance with the provisions of 7 Del.C. Ch. 60.
3.6 If any part of these Regulations, or the application of any part thereof, is held invalid or unconstitutional, the application of such part to other persons or circumstances, and the remainder of these Regulations, shall not be affected thereby and shall be deemed valid and effective.
3.7 These Regulations, being necessary for the health and welfare of the State and its inhabitants, shall be liberally construed in order to preserve the land, surface water and ground water resources of the State.
3.8 At the sole discretion of the Department, if the proposed operation of a system may cause pollution of public waters or create a public health hazard, system installation or use shall not be authorized.
3.9 All wastewater shall be treated and disposed of in a manner approved by the Department.
3.10 No person shall dispose of wastewater at any location not authorized by the Department under applicable laws and regulations for such disposal.
3.11 Discharge of untreated or partially treated wastewater or septic tank effluent directly or indirectly onto the ground surface or into surface waters of the State, unless authorized by a permit issued by the Department, constitutes a public health hazard and is prohibited.
3.12 No cooling water, air conditioning water, groundwater, oil, water softener brine or roof drainage shall be discharged into any system without specific authorization of the Department. Water softener brine shall be discharged in a manner that does not allow surface discharge (curtain drain).
3.13 Except where specifically allowed within these Regulations, no person shall connect a dwelling or commercial facility to a system if the total projected wastewater flow would be greater than that allowed under the original system construction permit.
3.14 Each system shall have adequate capacity to properly treat and dispose of the maximum projected daily wastewater flow. The quantity of wastewater shall be determined from these Regulations or other information the Department determines to be valid that may show different flows.
3.15 A permit to install a new system can be issued only if each site has received an approved site evaluation and is free of encumbrances (e.g., easements, deed restrictions, etc.) which could prevent the installation or operation of the system from being in conformance with these Regulations.
3.16 A recorded utility easement is required whenever a system crosses a property line separating property under different ownership. The easement must accommodate that part of the system, including setbacks, which lies beyond the property line, and must allow entry to install, maintain and repair the system.
3.17 Whenever real property is recorded as two separate lots under common ownership and an on‑site wastewater treatment and disposal system crosses the common boundary of the recorded lots, the owner shall execute and record, in the appropriate county office of Recorder of Deeds, an affidavit which notifies prospective purchasers of this fact on a form approved by the Department.
3.18 Except as provided in these Regulations, the spare area shall be kept vacant, free of vehicular traffic and soil modifications.
3.19 All systems shall be operated and maintained so as not to create a public health hazard or cause water pollution.
3.20 Exhibits A through Z are incorporated into these Regulations by reference.
3.21 No person shall transfer any portion of real property if the transfer would create a lot boundary which would cross an existing system or any part thereof including required setbacks and isolation distances unless, a utility easement is granted to the owner of the existing system and recorded in the appropriate county office of Recorder of Deeds.
3.22 The Department shall have the power to enter, at reasonable times, upon any private or public property for the purpose of inspecting and investigating conditions relative to the enforcement of these Regulations.
3.23 No person shall transfer any portion of real property after the issuance of a permit pursuant to these Regulations if the transfer would result in the use of the permitted on‑site system on a lot which does not comply with these Regulations and the terms of the permit, including density, set back and isolation distance requirements.
 
4.0 Licenses
4.1 The Department shall administer a program for the licensing of percolation testers, system designers, soil scientists, system contractors, system inpsectors and liquid waste haulers. The licensing program shall provide the issuance of licenses as follows;
4.1.1 Class A Percolation Tester: The Class A license authorizes the performance of percolation tests and other types of infiltrometer testing.
4.1.2 Class B Designer: The Class B license authorizes the design of conventional on‑site wastewater treatment and disposal systems which utilize gravity distribution systems for seepage beds and seepage trenches and lift pump stations as provided for in these Regulations.
4.1.3 Class C Designer: The Class C license authorizes the design of conventional and alternative on‑site wastewater treatment and disposal systems and all pressure distribution systems.
4.1.4 Class D Soil Scientist: The Class D license authorizes the performance of site soil evaluations, percolation and/or permeability tests or hydraulic conductivity tests.
4.1.5 Class E System Contractor: The Class E license authorizes the construction, repair and installation of on-site wastewater treatment and disposal systems.
4.1.6 Class F Liquid Waste Hauler: The Class F license authorizes the removal or disposal of the solid and liquid contents of septic tanks, cesspools, seepage pits, holding tanks or other wastewater treatment or disposal facilities as specified and required under these Regulations.
4.1.7 Class GB Designer: The Class GB license authorizes the design of combined well and conventional on‑site wastewater treatment and disposal systems which utilize gravity distribution systems for bed and trench designs.
4.1.8 Class GC Designer: The Class GC license authorizes the design of combined well and conventional and alternative on‑site wastewater treatment and disposal systems and all pressure distribution systems.
4.1.9 Class H System Inspector: The Class H license authorizes the inspection, investigation and data collection to make determinations regarding the present operational condition of on-site wastewater treatment and disposal systems.
4.2 It shall be necessary to have the Class A, Class B, Class C, Class D, Class E, Class F, Class GB, Class GC and Class H licenses in order to engage in the specified activities under Section 4.01000 of these Regulations except the Class H license will become effective January 1, 2006.
4.3 Any person seeking a license under this Section shall submit a complete application to the Department, on a standard form provided by the Department, references and pay the non-refundable application fee, if required. All applicants for a Class A, B, D, E, F, GB and/or H license will be required to pass an examination prepared and administered by the Department to test the competency and knowledge of the applicant regarding pertinent subject matter and the application and use of these Regulations. (GB and GC licenses shall not be available until §3.4 of the Regulations Governing the Construction and Use of Wells is amended.)
4.4 In the event an applicant fails to receive a passing grade on the examination, he/she shall be so notified by the Board within 30 days. The applicant may re-apply for a subsequent examination only after completion of a training course approved by the On-Site System Advisory Board (OSSAB). The examination may be taken no more than twice in a twelve (12) month time period.
4.5 With respect to Class C licenses the following shall constitute the Department's requirements:
4.5.1 Registration as a Professional Engineer with the Delaware Association of Professional Engineers; and
4.5.2 A complete qualifications statement on approved Department forms which verify the individual's knowledge and competency in the field of on‑site wastewater treatment and disposal system engineering and design.
4.6 With respect to Class D licenses the following shall constitute the Department's requirements:
4.6.1 A completed application on forms provided by the Department; a resume which demonstrates that the applicant has had relevant experience in the field of soil classification and mapping and/or site evaluations for on-site wastewater treatment and disposal systems; provide three (3) references; and one of the following (4.6.2, 4.6.3 or 4.6.4)
4.6.2 Six (6) years of professional experience under the supervision of an ARCPACS Professional Soil Classifier or Class D Soil Scientist in soil classification, mapping and interpretation with nine (9) semester hours in soil science and six (6) semester hours in geological sciences from accredited college or university; or
4.6.3 Four (4) years of professional experience under the supervision of an ARCPACS Professional Soil Classifier or Class D Soil Scientist in soil classification, mapping and interpretation and an undergraduate degree from an accredited college or university with nine (9) semester hours in soil science and six (6) semester hours in geological sciences; or
4.6.4 Two (2) years of professional experience under the supervision of an ARCPACS Professional Soil Classifier or Class D Soil Scientist in soil classification, mapping and interpretation and a graduate degree from an accredited college or university with thirty (30) semester hours in biological, physical and earth sciences and fifteen (15) semester hours in soil science; and
4.6.5 Pass a written examination administered by the Department to test the competency and knowledge of the applicant regarding site evaluations and pertinent information contained within the Regulations as it relates to siting on-site wastewater treatment and disposal systems; and one of the following (4.6.6 or 4.6.7)
4.6.6 Registration as a Professional Soil Classifier with the Federation of Certifying Boards in Agriculture, Biology, Earth and Environmental Sciences (ARCPACS); or
4.6.7 Pass a field practicum prepared and administered by the Site Interpretations Advisory Council and/or the Soil Scientists on the On-Site System Advisory Board. The field practicum shall assess whether competency exists for evaluating soils specific to Delaware.
4.7 With respect to Class E licenses the following shall constitute the Department's requirements:
4.7.1 A completed qualifications statement, on appropriate Department forms, which verify the individual’s knowledge and competency of the application and requirements of these Regulations; and
4.7.2 A minimum of two (2) years of experience in the construction of on-site wastewater treatment and disposal systems
4.8 With respect to Class GB licenses the following shall constitute the Department’s requirements:
4.8.1 A complete qualifications statement on approved Department forms which verify the individual's knowledge and competency in the field of gravity on‑site wastewater treatment and disposal systems; and
4.8.2 A complete qualifications statement on approved Department forms which verify the individual’s knowledge and competency in the placement of wells and the Regulations Governing the Construction and Use of Wells
4.9 With respect to Class GC licenses the following shall constitute the Department's requirements:
4.9.1 Registration as a Professional Engineer with the Delaware Association of Professional Engineers; and
4.9.2 A complete qualifications statement on approved Department forms which verify the individual's knowledge and competency in the field of engineering and the design of on‑site wastewater treatment and disposal systems
4.9.3 A complete qualifications statement on approved Department forms which verify the individual’s knowledge and competency in the placement of wells and the Regulations Governing the Construction and Use of Wells
4.10 With respect to Class H licenses the following shall constitute the Department’s requirements:
4.10.1 Furnishes certification of training completed under the National Association of Waste Transporters (NAWT) certification, Pennsylvania Septage Management Association (PSMA) certification, Delaware Technical & Community College certification program or as approved by the Board.
4.11 Responsibilities of Licensees
4.11.1 Any Class D licensed Soil Scientist may be required to notify the Department orally or in writing at least thirty‑six (36) hours, excluding Saturdays, Sundays and state holidays, prior to conducting the site evaluation. This is at the sole discretion of the Department.
4.11.2 All Class A, B, C, D, E, F, GB, GC and H licensees are responsible for correct and complete information submitted to the Department as it pertains to current Regulations.
4.11.3 All Class E licensed system contractors shall:
4.11.3.1 Initiate work only on systems for which a construction permit has been granted; and
4.11.3.2 Comply with all applicable Regulations and requirements; and
4.11.3.3 Be responsible for the work carried out by their employees; and
4.11.3.4 Submit to the Department within ten (10) days of completion of a system, a Construction Report on forms provided by the Department, signed by the licensed contractor; and
4.11.3.5 Notify the Department 24 hours prior to construction start up to receive an authorization number, except newly licensed contractors must notify the Department forty eight (48) hours prior to initial six (6) construction start ups to receive an authorization number; and
4.11.3.6 Be the sole contact person to the Department regarding inspection call-ins, consequential changes or problems. An individual employed by the licensee may be the contact person for inspection call-ins provided that person is a Class E licensee or has been designated as a contact person in writing to the Department by the licensee prior to calling; and
4.11.4 All Class F licensed liquid waste haulers shall:
4.11.4.1 Remove all wastewater from the appropriate tanks in accordance with the guidelines as set forth by the Department; and
4.11.4.2 May repair, add or replace septic tank and/or holding tank risers, baffles, lids, distribution box lids and effluent filters.
4.11.5 All Class H System Inspectors shall perform:
4.11.5.1 All inspections of on-site wastewater treatment and disposal systems shall be submitted to the Department on forms approved by the Department (See Exhibit A for the inspection form example and guidelines). These forms shall be submitted within seventy two (72) hours of inspection completion.
4.11.6 Any person who engages in the practice of professional engineering or professional geology in the specified activities under this Section shall be duly registered in conformance with the requirements of the laws of the State of Delaware.
4.11.7 The Department may issue temporary Class A, B, or E licenses to property owners who wish to conduct their own percolation testing, system design, or system installation on their own property and for their own use. Certification of the intended use will be required. The applicant shall submit an application on Department forms along with any required fee and shall demonstrate his competency in those fields by successfully completing a test conducted by the Department. The term of the temporary Class A, B, or E license shall expire upon completion of work conducted by the applicant for which the permit was issued.
4.12 In exercising exclusive licensing authority under this section, the Department shall seek the views of an On‑Site Systems Advisory Board (OSSAB) regarding licensing matters. The Board shall consist of eight (8) members designated by the Secretary. The Board shall, if possible, have one (1) member who is a representative of the Department, one (l) member who is a Professional Engineer, one (1) member who is a Professional Geologist, one (1) member who is a representative of the USDA, one (1) member who is a Class D Soil Scientist, one (1) member who is a Class E System Contractor, one (1) member who is a Class F Liquid Waste Hauler and one (1) member who is a Class H System Inspector. The members of the Board shall serve at the discretion of the Secretary. The Board shall advise the Department on matters relating to issuance of Class A, Class B, Class C, Class D, Class E, Class F, Class GB, Class GC and Class H licenses.
4.12.1 Upon adoption of these Regulations, the applicant for a license renewal shall submit with the renewal application proof that he/she has attended and/or satisfactorily completed a minimum of ten (10) hours of continuing education training relating to the wastewater industry. This is to include siting, design, construction, operation and/or maintenance of on-site wastewater treatment and disposal systems. Class D Soil Scientists not ARCPAC certified must attend at least three (3) hours of soil related curriculum. Any training must be sponsored by recognized governmental, educational or industrial groups which include equipment manufacturers and be approved by the OSSAB. The number of hours of continuing education for first year licensees will be decided by the OSSAB and be based upon license issuance date.
4.12.2 The Secretary may suspend or revoke the license of a Class A, B, C, D, E, F, GB, GC or H licensee after considering the recommendations of the OSSAB and demonstration that the licensee has practiced fraud or deception; that reasonable care, judgment, or the application or their knowledge or ability was not used in performance of their duties; or that the licensee is incompetent or unable to perform their duties properly or;
4.12.2.1 Violated any provision of these Regulations;
4.12.2.2 Violated any lawful order or rule rendered or adopted by the Department;
4.12.2.3 Obtained his/her license or any order, ruling, or authorization by means of fraud, misrepresentation, or concealment of material facts;
4.12.2.4 Failure to obtain the necessary hours of continuing education training required by these Regulations;
4.12.2.5 Been found guilty of misconduct in the pursuit of his/her profession
4.13 Any person whose application for a license has been denied or person whose license has been suspended or revoked shall be notified in writing and provided reasons for the decision. Within twenty (20) days of notification, the person shall notify the Secretary, in writing, if an appeal pursuant to 7 Del.C. Ch. 60, §6008 is to be requested. If no appeal request is received within the designated period the decision shall become final.
4.14 Licenses issued pursuant to this Section are not transferable and shall expire on December 31st of each year. A license may be renewed yearly without examination for an ensuing year provided the licensee makes application for renewal by November 30th of each year, shows proof of the number of hours of continuing education training and pays any applicable renewal fees adopted by the Department. If the licensee fails to renew the license he/she may reapply, without examination, within the first year. If more than a year passes the licensee must reapply for the license and take all necessary examinations. A reminder will be sent to the licensee to renew his/her license by the Department. The reminder will be sent to the address on file for the licensee. It is the licensee’s responsibility to renew the license yearly and notify the Department of any changes.
 
5.0 Site Evaluations and Permits
5.1 Site Evaluation Procedures
5.1.1 A site evaluation is the first step in the process of obtaining a construction permit for an on‑site wastewater treatment and disposal system. Any person applying for a permit to install a new or replacement on‑site wastewater treatment and disposal system shall first obtain a site evaluation report prepared by a Class D Soil Scientist. The Department shall conduct site evaluations only for Home Rehabilitation Loan Programs (HRLP), block grant households, State Revolving Fund (SRF) sites and other qualifying income programs with similar criteria.
5.1.2 Site evaluations performed for the purpose of siting large/community systems refer to the necessary criteria in §5.14.
5.1.3 Each report shall be completed in full and be accompanied, at a minimum, by approval page(s) (excluding sites not suitable for conventional on-site wastewater treatment and disposal systems), report page(s), site drawing, soil profile notes, zoning verification form and the appropriate fee. The site evaluation report shall contain specific site conditions or limitations including, but not limited to, isolation and separation distances, slopes, existing wells, cuts and fills, and unstable landforms.
5.1.4 The Class D Soil Scientist shall specify on the approval page the type of on-site wastewater treatment and disposal system that may be constructed in the acceptable on-site disposal area as indicated on the site drawing. Any other on-site wastewater treatment and disposal options available in the evaluated area shall be specified by the Class D Soil Scientist. The evaluator shall either assign a percolation rate or have the appropriate hydraulic conductivity or percolation test conducted in the proposed disposal area prior to submittal.
5.1.5 A site drawing drawn to scale showing the information referenced in §5.1.10. All site drawings are required to show a reference point such as a numbered utility pole, telephone or electrical box, building(s), property corners or fixed survey marker. A minimum of two reference points shall be noted on the site drawing when no land survey boundary stakes or markers are readily identifiable in the field, or if the site drawing is not based on a survey conducted by a licensed land surveyor. However, if the site drawing is based on a survey conducted by a licensed land surveyor, the property corner stakes or markers will suffice for identification of the parcel. Site drawing(s) shall be based on an even number scale, not to exceed 1 inch equals 100 feet. Any site drawing exceeding the dimensions of 8.5 inches X 11 inches must be submitted in duplicate.
5.1.6 Showing the location of all on-site and adjacent wells within 150 feet of the approved soils area is the responsibility of the Class D Soil Scientist. The following procedure shall be used in all cases when on-site or adjacent well(s) cannot be located. For instances where the on-site or adjacent well(s) are below ground and the homeowner or adjacent property owner states that the well is located in a certain area, this information shall suffice for verification of well location. Any well(s) that can not be verified must be researched through the Water Supply Section of the Department. The search attempts to locate any well(s) that are near the affected parcel. If, after this search is completed, the well location(s) cannot be identified the Class D Soil Scientist can state “records were researched under this property owner’s name and no information was found”. The Department then sends a letter to the adjacent well owners notifying them of the need to locate their well(s) due to the future installation of an on-site wastewater treatment and disposal system. If no response is rendered within fifteen (15) days of receipt then the new system is to be designed to maximize the isolation distance from the property line.
5.1.7 A site evaluation prescription shall follow an approach that includes consideration of topography, available area, slope gradient and uniformity, soil profile (thickness and depth of each horizon, color, percolation, absorption rate, redoximorphic features, texture (see Exhibit B), and zones of saturation), drinking water supplies, bodies of water, and shellfish growing areas. All suitable soils within the evaluated area shall be delineated regardless of isolation distances, encumbrances and easement requirements as well as any of the above conditions which may exist.
5.1.8 All soil borings, holes and/or pits shall be flagged, identified and adequately shown on the site drawing.
5.1.9 In describing the soils and soil profile, the Class D Soil Scientist shall adhere to the procedures and techniques provided in the latest edition of the Soil Survey Manual, USDA Agricultural Handbook No. 18, as published by the U.S. Department of Agriculture.
5.1.10 The report shall contain, at a minimum, a site drawing and observations of the following site characteristics, if present:
5.1.10.1 Parcel size, location map of project site, configuration and approximate dimensions
5.1.10.2 Slope ‑ percent and direction
5.1.10.3 Surface streams, springs or other bodies of water and their definition (i.e. shellfish, intermittent, ephemeral, etc.)
5.1.10.4 Existing wells within 150 feet of approved soils area
5.1.10.5 Escarpments
5.1.10.6 Cuts and fills
5.1.10.7 Unstable landforms
5.1.10.8 A representative number of soil profile descriptions in the evaluated area(s) and shall identify the soil series or classification to the subgroup level (i.e. Sassafras or Typic Hapludult). The geographic coordinates of each representative soil boring, a minimum of two (2), must be determined by a global positioning system. The coordinates should be reported in the following format – Latitude DD.ddddd & Longitude DD.ddddd – (5 decimal places are required for accuracy).
5.1.10.9 Zones of saturation (as indicated by redoximorphic features)
5.1.10.10 Approved soils area(s)
5.1.10.11 Encumbrances
5.1.10.12 Central wastewater or water systems availability
5.1.10.13 Any other applicable information such as hydric soils (if any recorded state or federal wetlands) or refer to Statewide Wetland Mapping Project (SWMP)
5.1.10.14 Any overhead utilities
5.1.10.15 Existing dwellings
5.1.11 The application/construction permit report may be submitted with the site evaluation, in an emergency situation, when there is a public health risk associated with a malfunctioning system. The permit shall not be approved until the site evaluation is reviewed and complies with these Regulations. Site evaluations needed to replace the malfunctioning system shall be given a priority review.
5.1.12 Once received, the report shall be reviewed for compliance with current Regulations by a DNREC Environmental Scientist with a soil science background. If the report is in non‑compliance, the Class D Soil Scientist shall be notified. The Class D Soil Scientist shall contact the Department to rectify the discrepancy. The Department shall not modify any site evaluation report unless requested by the Class D Soil Scientist. The corrections shall be submitted to the Department from the evaluator and a corrected copy to the owner, etc. The review process, which may include a field check, shall take place within ten (10) working days of receipt. (NOTE: If approval cannot be issued within ten (10) working days, the property owner or authorized agent shall be notified of the delay and a tentative date of approval or denial shall be given). Once approved, the report shall be mailed to the property owner or his/her authorized agent. A percentage of randomly chosen site evaluations submitted shall be field verified by DNREC staff. Site evaluations’ requiring test pits should be reported to the Department prior to conducting the site evaluation.
5.1.13 Approval of a site evaluation indicates only that the site evaluation was conducted in compliance with these Regulations. It is not an indication of the correctness or quality of the site evaluation nor an indication that a permit can be issued.
5.1.14 The approved site evaluation report shall indicate the type of the initial and type of replacement system for which the site is approved.
5.1.15 Technical regulation changes shall not invalidate an approved site evaluation but may require the use of a different type of system.
5.1.16 The approved site evaluation shall be valid for five (5) years from the date of the Department’s approval or the adoption of this Regulation revision unless a subdivision base plan restricting well and on-site wastewater treatment and disposal system locations has been approved by the Department and recorded in the local Recorder of Deeds Office. After the five (5) year period, a site evaluation as outlined in §5.1.10, shall be submitted to the Department for approval. This site evaluation will be reviewed as outlined in §§5.1.11 and 5.1.12.
5.1.17 Supplemental soil information submitted after the original site evaluation has been approved shall include a revised approval page, report page, soil profile notes, and revised site drawing locating supplemental borings/test pits. In all cases, the new report shall be approved provided all criteria for approval are met. If the purpose of supplemental work is to change the type of system previously prescribed, another review fee shall be required. Likewise, any borings/test pits conducted greater than 100 ft. from the previously approved area, with or without a system change, shall require a review fee. On larger parcels, the area evaluated shall be delineated on the site drawing.
5.1.18 The Department shall issue a notice of its intention to deny a site evaluation when appropriate. Alternative technologies for on‑site wastewater treatment and disposal systems, if appropriate, may be included in the letter. The applicant still maintains his/her right to appeal the decision of the Secretary, within twenty (20) days of receipt, in accordance with 7 Del.C. Ch. 60, §6008.
5.1.19 A property owner or agent has the option to use observation wells and/or piezometers to demonstrate that redoximorphic features are not an indication of zones of saturation. The following procedures for the use of observation wells/piezometers to determine the depth and duration of zones of saturation shall be implemented.
5.2 Observation Wells/Piezometers
5.2.1 Determining the zones of saturation using observation wells and/or piezometers follow these procedures:
5.2.1.1 The property owner or authorized agent shall notify the Department, in writing, of the intent to use observation wells and/or piezometers to determine the zones of saturation.
5.2.1.2 At least three (3) observation wells and/or piezometers shall be installed and monitored at a site. If, in the judgment of the Department, more than three (3) are needed, the property owner or agent shall be notified in writing within ten (10) days of receipt of the letter of intent.
5.2.1.3 The design illustrated in Exhibit Y shall be used when constructing observation wells and/or piezometers. At least two (2) wells/piezometers shall extend to a depth of six (6) feet, at a minimum, below ground surface. However, with layered mottled soil over permeable unmottled soil, at least one (1) well/piezometer shall terminate within the mottled layer. Site conditions may, in some cases, require monitoring at greater depths. It shall be the responsibility of the Class D Soil Scientist to determine the depth of the observation wells and/or piezometers for each site and, if in doubt, they shall request the guidance of the Department.
5.2.1.4 All observation wells are required to be permitted in accordance with the current Regulations Governing the Construction and Use of Wells.
5.2.1.5 Observation wells and/or piezometers shall be installed by or under the direct on-site supervision of a well driller licensed by the State of Delaware in accordance with the current Regulations Governing the Construction and Use of Wells.
5.2.1.6 Monitoring of water levels shall be done by an individual who is licensed by the Division of Water Resources. The property owner/agent or any relative shall not, at anytime, be allowed to monitor the water levels of these wells.
5.2.1.7 The preferred monitoring is from December 1st through May 15th of the following year to verify the depth and duration of the zones of saturation during years of near normal precipitation for fall, winter and spring seasons. However, the Class D Soil Scientist may, at his/her discretion, allow clients to install wells at any time he/she deems appropriate. Depending on when peaks are observed, the State may or may not accept the monitoring for that season. A near normal monitoring period is defined as a period that has plus or minus one standard deviation of the long term mean annual precipitation. (Long term refers to 30 or more years). Also, the mean monthly precipitation during a normal period must be plus or minus one standard deviation of the long term monthly precipitation for 8 of the 12 months. For the most part, normal years can be calculated from the mean annual precipitation.
5.2.1.7.1 The Department shall field check the monitoring periodically during the time of expected saturated soil conditions at their discretion.
5.2.1.7.2 The Department may, at any time during the observation period, verify the observed water depth by conducting a soil boring next to, and of equal depth with, any of the observation wells/piezometers. If the water level in the fresh boring, after twenty four (24) hours, presents a discrepancy with the water level observed in the well/piezometer, then at the discretion of the Department, the data may be declared invalid. If the data is declared invalid, then the Department will notify the owner in writing of the invalid data within ten (10) days of determination.
5.2.2 When monitoring determines that the site is suitable, the Department will request that a new site evaluation be submitted. The monitoring information must be incorporated into the new site evaluation. An approved site evaluation report shall be issued indicating the appropriate system type(s).
5.2.3 Observation wells and/or piezometers are required to be abandoned in accordance with the current Regulations Governing the Construction and Use of Wells.
5.3 Site Interpretation Advisory Council
5.3.1 The purpose of the Site Interpretation Advisory Council (Council) is to act as an objective peer group in the review of discrepancies between the Department and Class D Soil Scientists regarding questions of interpretation of soil and site information for the purpose of siting on‑site wastewater treatment and disposal systems.
5.3.2 The Council shall restrict its charge to those items normally and commonly addressed when conducting a site evaluation as discussed below. The Council specifically excludes instances regarding the engineering design and/or installation of on-site wastewater treatment and disposal systems except when it is directly applied to the soil science practice.
5.3.2.1 The description and interpretation of soil morphology in regard to the proper functioning of on‑site wastewater treatment and disposal systems utilizing the soil as part of the treatment process.
5.3.2.2 The characterization of lithologic and hydrologic limiting layers and geomorphology pertinent to the proper siting and functioning of on-site wastewater treatment and disposal systems.
5.3.2.3 The recognition and documentation of site limitations for the placement of on‑site wastewater treatment and disposal systems (i.e. existing wells and on-site wastewater treatment and disposal systems) in accordance with standard practice in Delaware.
5.3.3 The Site Interpretation Advisory Council shall be appointed by the Secretary and consist of the following members:
5.3.3.1 Four (4) non‑governmental Class D Soil Scientists actively practicing in the State of Delaware for two (2) or more years with one (1) acting as an alternate.
5.3.3.2 One (1) employee of the Department with soils and on‑site wastewater industry expertise.
5.3.3.3 One (1) soil scientist designated by the State Conservationist through the State Soil Scientist, NRCS, USDA.
5.3.3.4 A Manager of the Ground Water Discharges Section (GWDS), DNREC, shall serve as a liaison to the Council without voting privileges.
5.3.3.5 All members shall serve three (3) year terms. Procedures shall be established by the Council to stagger terms so as to provide continuity.
5.3.4 Documentation and testimony regarding a review shall be submitted to the Council. After the initial review by the Council, a determination shall be made as to whether sufficient information has been submitted to render an informed decision. The Council may request additional information from the applicant before proceeding with the review. There shall be no cost to the Council for any information submitted.
5.3.5 Within thirty (30) days from receipt of the documentation, the Council shall render a decision, based on a simple majority vote, regarding which system(s), if any, are suitable under the Delaware Regulations.
5.3.6 A site visit shall be conducted by at least four (4) members of the Council. The applicant is responsible for all costs that may be incurred. Council members shall not be reimbursed for any expenses.
5.3.7 Any decision rendered by the Council shall be considered by the Secretary and may be a deciding factor in his/her decision. The applicant still maintains his/her right to appeal the decision of the Secretary in accordance with 7 Del.C. Ch. 60, §6008.
5.3.8 The Council shall designate one of its members representing the private sector to serve as chairperson for a period of one year. The chairperson, or his/her designee, serving as the principal contact person between the Council and a Manager of the GWDS, shall perform the following duties:
5.3.8.1 Call and preside at all Council meetings. (A GWDS Manager may also call a meeting, but is not entitled to preside at a Council meeting.)
5.3.8.2 Upon receipt of a request, poll the Council members and communicate the results to the GWDS Manager calling a Council meeting when appropriate. (This function may also be performed by the GWDS Manager, when necessary.)
5.3.8.3 Prepare a letter communicating the Council’s decision in each case. (The letter shall be sent within fifteen (15) working days after the Council’s decision to the GWDS Manager for signature and returned for mailing within three (3) working days.)
5.3.9 The following services shall be furnished by the DNREC to facilitate the operation of this Council:
5.3.9.1 A Manager of the GWDS shall represent the Section’s position at all Council meetings.
5.3.9.2 All submittals for consideration shall be circulated to the Council under the direction of the GWDS Manager within ten (10) working days.
5.3.9.3 A GWDS Manager, at the request of the Council chairperson, shall reserve space in the DNREC facilities for Council meetings.
5.3.9.4 The DNREC shall provide clerical services for record keeping. Records of the Council meetings shall be furnished to all Council members within fifteen (15) working days following the meetings.
5.3.9.5 The clerical person shall prepare and mail the decisions of the Council upon receipt from the chairperson.
5.3.10 The Council shall restrict reviews to those submittals directly affected by the expertise of the NRCS Soil Scientist’s decision, using one of the following two (2) methods:
5.3.10.1 A submittal from the Secretary, DNREC; or
5.3.10.2 A submittal from a Class D Soil Scientist.
5.3.11 All submittals shall be circulated to the Council membership. A majority vote of the Council is required for any submittal to be accepted for Council review.
5.4 Permit Application Procedures ‑ General Requirements
5.4.1 No person shall cause or allow construction, alteration, or repair of a system, or any part thereof, without a permit. An exception may be allowed for certain emergency repairs as set forth in these Regulations.
5.4.2 Permit applications must be designed in accordance with the prescribed system type and design considerations as specified on an approved site evaluation or Soils Investigative Report for that parcel.
5.4.3 Applications for permits shall be made by the owner of the property or the owner's legally authorized agent on forms approved by the Department.
5.4.4 An application is complete only when the form is completed in full, signed by the owner or the owner's legally authorized agent, accompanied by all required exhibits (provided an approved site evaluation report is on file) and fee. And a form from the appropriate governmental unit having jurisdiction, a statement that the local governmental unit has approved the activity by zoning. Incomplete applications will not be processed and may be returned.
5.4.5 The Department shall deny the permit if:
5.4.5.1 The application contains false information;
5.4.5.2 The proposed system would not comply with these Regulations;
5.4.5.3 The proposed system, if constructed, would violate a Department moratorium;
5.4.5.4 A central wastewater system which can serve the proposed wastewater flow is both legally and physically available as described in §§5.4.7 and 5.4.8 of these Regulations;
5.4.5.5 Construction of an on-site wastewater treatment and disposal system is prohibited by codes, ordinances or county or municipal regulations having jurisdiction
5.4.6 The completed application shall include, at a minimum, the following site information;
5.4.6.1 Parcel and/or lot dimensions and size with a location map of project site;
5.4.6.2 Slope - in absorption facility and replacement areas (percent and direction);
5.4.6.3 Existing wells within 150 feet of the proposed system;
5.4.6.4 Any and all watercourses or bodies of water;
5.4.6.5 Distances of the on-site well(s) and on-site wastewater treatment and disposal systems from the nearest two fixed points of reference. Points of reference as defined in §5.1.5;
5.4.6.6 Soil boring and test pit locations along with limits of approved area as indicated on the approved site evaluation;
5.4.6.7 Any other information required to satisfy these Regulations
5.4.7 A central wastewater system shall be deemed physically available if its nearest connection point from the property to be served is:
5.4.7.1 For a single family dwelling, or other establishment with a maximum projected daily wastewater flow of not more than five hundred (500) gallons within two hundred (200) feet;
5.4.7.2 For a proposed subdivision or group of two (2) to five (5) single family dwellings, or equivalent projected daily wastewater flow, not further than two hundred (200) feet multiplied by the number of dwellings or dwelling equivalents.
5.4.7.3 For proposed subdivision or other developments with more than five (5) single family dwellings, or equivalents, the determination of central wastewater availability shall be in the sole discretion of the Department.
However, a central wastewater system shall not be considered available by the Department if topographic or manmade features make connection physically impractical.
5.4.8 A central wastewater system shall be deemed legally available if the system is not under a Department connection permit moratorium and the wastewater system owner is willing or obligated to provide sewer service.
5.4.9 When a central wastewater system is deemed both physically and legally available, as outlined in §§5.4.7 and 5.4.8, the connection must occur within a timeframe as set forth by the wastewater system owner. The existing on-site system must be abandoned in accordance with §5.8.
5.4.10 A permit shall be issued only to the owner or easement holder of the land on which the system is to be installed.
5.4.11 The Department shall either issue or deny the permit within twenty (20) working days after receipt of the completed application. However, if conditions prevent the Department from acting to either issue or deny the permit within twenty (20) working days, the applicant shall be notified. The Department shall either issue or return the permit within thirty (30) working days after the mailing date of such notification.
5.4.12 All permits issued for on-site wastewater treatment and disposal systems pursuant to these Regulations shall be effective for two (2) years from the date of issuance. If the system has been started the Department may issue a limited time period extension. A one year extension will, if requested, be granted by the Department upon demonstration by the applicant that no changes have occurred in system design, siting, or regulations applicable to the permit since the permit was issued and written certification to such factual findings is provided and all appropriate fees are paid.
5.4.13 If any portion of the approved disposal area is disturbed during site construction activities, through grubbing, tree removal or other activities utilizing heavy equipment, a Class E System Contractor must submit a certification document, if necessary, prepared by a Class D Soil Scientist on a form provided by the Department which states whether the area is suitable for installation or not. If not suitable, additional soil borings or test pits shall be performed within the disturbed area(s) to substantiate the initial site evaluation.
5.5 Permit Denial Review
5.5.1 The Department shall make a decision on the application which it determines will best implement the purposes of 7 Del.C. Ch. 60 and these Regulations. Providing of the requisite information in the application procedure by the applicant shall not be construed as a mandatory prerequisite for the issuance of the permit by the Department.
5.5.2 Permit denials for systems and denial reviews may be appealed to the Environmental Appeals Board in accordance with 7 Del.C. Ch. 60, §6008.
5.5.3 If the Department intends to deny a permit for a parcel of ten (10) acres or larger in size, the Department shall:
5.5.3.1 Provide the applicant with a Notice of Intent to Deny;
5.5.3.2 Specify reasons for the intended denial; and
5.5.3.3 Offer an appeals process in accordance with 7 Del.C. Ch. 60, §6008.
5.6 Inspections
5.6.1 Construction Inspections
5.6.2 The Class E System Contractor shall contact the Department 24 hours prior to system construction to obtain a startup number to authorize the construction.
5.6.3 Changes to a permit which result in only a relocation of the system can be done by submitting a pre-inspection as-built, which requires a minimal check against the site evaluation to ensure the system is still located within approved soils and that all required isolation distances are met. These “as-builts” are to be submitted to the Department by the Class E System Contractor prior to installation. The Class E System Contractor must obtain permission from the designer prior to submittal.
5.6.4 When construction, alteration or repair of a system is complete, except for backfill (cover), or as required by permit, the Class E System Contractor shall notify the Department. The inspector shall inspect the installation to determine if it complies with these Regulations and the terms and conditions of the permit, unless the inspection is waived by the Department in accordance with §5.6.7.
5.6.5 It is the responsibility of the Class E System Contractor to confirm the results of the pre-cover inspection prior to backfilling the system.
5.6.6 An inspector shall be either:
5.6.6.1 An employee of the GWDS;
5.6.6.2 A Class C Designer or his/her designee. The Class C designer must submit a list of authorized personnel, on company letterhead, to the Department for review and approval.
5.6.6.3 Any person officially authorized by the Department to perform inspections of on-site wastewater treatment and disposal systems.
5.6.7 The Department may waive the pre‑cover inspection, provided:
5.6.7.1 The installation is an on-site wastewater treatment and disposal system installed by a licensed Class E System Contractor pursuant to these Regulations; and
5.6.7.2 After system completion the Class E System Contractor provides a construction report which certifies in writing that the system complies with the Department's Regulations. If any changes were made to the system the Class E System Contractor must provide a detailed “as‑built” plan (drawn to scale).
5.6.8 Failure to comply with Departmental Regulations and the conditions of the permit will result in verbal notification to the Class E System Contractor. Failure to correct deficiencies within ten (10) calendar days (weather permitting) will result in written notification of such to both the Class E System Contractor and permittee. Additional inspections may be required by the Department.
5.6.9 Once a system has received a satisfactory pre-cover inspection or authorization to cover without a Departmental inspection, the system may be covered as specified in the approved permit. Backfilling must be completed within ten (10) calendar days of a satisfactory pre-cover inspection, weather permitting.
5.6.10 Systems requiring earthen caps and all mound systems shall require a final cover inspection pursuant to §5.6.4 or 5.6.7. Capping of systems must be completed within ten (10) calendar days of a satisfactory pre-cover inspection or authorization to cover without Departmental inspection, weather permitting.
5.6.11 Inspections performed by Class C Designers shall conform to guidelines established by the Department.
5.6.12 In situations where the Class C Designer is not comfortable approving a system, he/she is to contact the Department immediately.
5.6.13 Existing System Inspections
5.6.14 An existing system inspector shall be either:
5.6.14.1 An employee of the GWDS; or
5.6.14.2 A Class H system inspector; or
5.6.14.3 Any person officially authorized by the Department to perform inspections of on-site wastewater treatment and disposal systems.
5.7 Certificate of Satisfactory Completion
5.7.1 The Department shall issue a Certificate of Satisfactory Completion, if, upon inspection of the installation, the system complies with the Department's Regulations, the conditions of the permit, and a construction report is submitted to the Department.
5.7.2 A system shall be backfilled (covered) when:
5.7.2.1 The Class E System Contractor is notified by the Department that inspection has been waived; or
5.7.2.2 The inspection has been done and authorization has been granted to cover the system
5.7.3 Corrections necessary to meet requirements for satisfactory completion shall be made within seven (7) calendar days after written notification by the Department, unless otherwise required.
5.7.4 A Certificate of Satisfactory Completion shall be valid for a period of two (2) years from the date of issuance. After the two (2) year period, the Regulations for Authorization to Use an Existing System Permit or Alteration Permit apply.
5.7.5 Denial of a Certificate of Satisfactory Completion may be appealed in accordance with 7 Del.C. Ch. 60, §6008.
5.7.6 If the system has been placed into operation without the required Certificate of Satisfactory Completion, a Notice of Non-Compliance shall be issued to the owner and must be corrected within ten (10) calendar days or system must be abandoned in accordance with §5.8.3.
5.8 Abandonment of Systems
5.8.1 General Requirements
5.8.1.1 All systems shall be abandoned by a Class E System Contractor or other governmental appointee.
5.8.1.2 Within ten (10) calendar days of abandonment, the Class E System Contractor shall submit a System Abandonment Report on a form provided by the Department (see Exhibit Z). The report shall be filled out completely and signed by the contractor.
5.8.2 The system shall be properly abandoned when:
5.8.2.1 A central wastewater system becomes available and the building sewer has been connected thereto; or
5.8.2.2 The source of wastewater has been permanently eliminated; or
5.8.2.3 The system has been operated in violation of these Regulations, until a repair permit and Certificate of Satisfactory Completion are subsequently issued; or
5.8.2.4 The system has been constructed, installed, altered, or repaired without a required permit authorizing same, unless, and until a permit is subsequently issued
5.8.3 Procedures for Abandonment:
5.8.3.1 The septic tank, cesspool or other treatment unit shall be pumped by a Class F Liquid Waste Hauler to remove all of the contents;
5.8.3.2 The septic tank, cesspool or other treatment unit shall be removed or filled with sand, bank run gravel, or other material approved by the Department;
5.8.3.3 The system building sewer shall be permanently capped
5.9 Authorization to Use an Existing System Permit
5.9.1 Application for an Authorization to Use an Existing System Permit shall be made on forms provided by the Department and shall be accepted only when the forms are complete.
5.9.2 No person shall place into service, change the use of or increase the projected daily wastewater flow above design standards into an existing system without first obtaining an Authorization to Use an Existing System Permit or Alteration, Repair or Replacement Permit as appropriate.
5.9.3 An Authorization to Use an Existing System Permit is not required:
5.9.3.1 Where there is a replacement of a manufactured home with similar units in manufactured home communities with on‑site wastewater treatment and disposal systems when an annual inspection has taken place by the Department or an authorized designee certifying that the existing system(s) is/are not malfunctioning.
5.9.3.2 For use of a previously unused system for which a Certificate of Satisfactory Completion has been issued within one (l) year of the date that such system is placed into service, provided the projected daily wastewater flow does not exceed the design flow.
5.9.4 For changes in the use of an existing system where no increase in wastewater flow above design standards is projected, or where the design flow is not exceeded an Authorization to Use an Existing System Permit shall be issued if:
5.9.4.1 The existing system is not malfunctioning; and
5.9.4.2 All isolation distances from the existing system can be maintained; and
5.9.4.3 The proposed use would not create a public health hazard; and
5.9.4.4 If the Department has no record of an existing on-site wastewater treatment and disposal system, no connection to that system shall be permitted until an inspection has been performed provided the following are uncovered and left uncovered prior to the inspection:
5.9.4.4.1 Septic tank
5.9.4.4.2 Distribution box
5.9.4.4.3 Corners of each trench or the bed (additional area may be required upon inspection)
5.9.5 If the conditions of §5.9.4 cannot be met, an Authorization to Use an Existing System Permit shall be withheld until such time as alterations and/or repairs to the system are made.
5.9.6 For changes in the use of a system where projected daily wastewater flows would be increased above design criteria an Alteration, Repair or Replacement permit must be obtained.
5.9.7 The Department may allow a manufactured home to use an existing system serving another dwelling, in order to provide temporary housing for a family member suffering hardship, by issuing an Authorization to Use an Existing System Permit, if:
5.9.7.1 The Department receives satisfactory evidence which indicates the family member is suffering physical or mental impairment, infirmity, or is otherwise disabled and is in need of temporary housing; and
5.9.7.2 The system is not malfunctioning; and
5.9.7.3 The application is for a manufactured home; and
5.9.7.4 Evidence is provided that a hardship manufactured home placement is allowed on the subject property by the governmental agency that regulates zoning, land use planning, and/or building; and
5.9.7.5 A full system replacement area is available according to an approved site evaluation
5.9.8 An Authorization to Use an Existing System Permit issued for personal hardship shall remain in effect for a specified period, not to exceed cessation of the hardship. The Department shall impose conditions in the Authorization to Use an Existing System Permit that are necessary to ensure protection of public health. If the system fails and additional replacement area is no longer available, the manufactured home must be removed from the property.
5.10 Alteration of Existing Systems:
5.10.1 No person shall alter or increase the design capacity of an existing system without first obtaining an Alteration Permit.
5.10.2 No person shall increase the projected daily wastewater flow into an existing system beyond the design capacity of the system until an Alteration Permit is obtained.
5.10.3 The Department may issue an Alteration Permit if:
5.10.3.1 The existing system is not malfunctioning; and
5.10.3.2 An approved site evaluation report has been obtained; and
5.10.3.3 The proposed installation will be in compliance with these Regulations
5.10.4 Upon completion of installation of that part of a system for which an Alteration Permit has been issued, the permittee shall obtain a Certificate of Satisfactory Completion from the Department.
5.11 Repair and Replacement of Existing Systems
5.11.1 Steps to repair a malfunctioning system shall be initiated immediately and continued until system repair is completed. However, if, at the sole discretion of the Department, it is determined that adverse soil conditions exist due to climatic conditions that would likely preclude a successful repair, the Department may allow a delay in commencing repairs until the soil conditions improve. If this allowance is made, a compliance date and interim system maintenance requirements shall be specified in system construction deficiencies to the system owner.
5.11.2 No person shall repair a malfunctioning system without first obtaining a Repair Permit. Emergency repairs of broken system components, as specifically defined in these Regulations (see §2.0), may be made without first obtaining a permit provided a permit is applied for within three (3) working days after the emergency repairs are begun. Such a delayed application submittal does not relieve any person from complying with subsequent requirements or conditions of approval as may be imposed by the Department.
5.11.3 Upon completion of installation of that part of a system for which a Repair Permit has been issued, the permittee shall obtain a Certificate of Satisfactory Completion from the Department.
5.11.4 The following criteria for a Repair or Replacement Permit shall apply:
5.11.4.1 If the site characteristics and standards described in these Regulations can be met, then the repair installation shall conform to them.
5.11.4.2 If the site characteristics or standards described in these Regulations cannot be met, the Department may allow a reasonable repair or replacement installation in order to eliminate a public health hazard. Reasonable repairs or replacements may require the installation of an alternative system in order to eliminate a public health hazard. In such cases the Department shall use its best professional judgment in approving repairs or replacements that will reasonably enable the system to function properly.
5.11.5 Malfunctioning systems that cannot be repaired shall be abandoned in accordance with these Regulations.
5.12 Alternative Wastewater Treatment and Disposal Systems
5.12.1 Alternative technology on‑site wastewater treatment and disposal systems may be appropriate for areas where site constraints limit the suitability for conventional system types. The Department shall consider applications for alternative wastewater treatment and disposal systems on a case‑by‑case basis. It is the policy of the Department to pursue a program of experimentation for the purpose of obtaining sufficient data for the development of alternative wastewater treatment and disposal systems, which may benefit the people of Delaware. For the purposes of this section, applications for community systems that employ advanced treatment units which are in conformance with standard engineering practice as determined by the Department shall not be considered alternative.
5.12.2 Applications for alternative on-sitewastewater treatment and disposal systems shall provide documentation of the capabilities of the proposed system. Such documentation shall be in the form of proven data of long term usage of facilities similar to those specified in these Regulations, or short term documentation from controlled projects from reliable sources such as Universities or the National Sanitation Foundation. The Department shall approve only treatment and disposal system applications that provide thorough documentation of proven technology. Alternative on-site wastewater treatment and disposal systems shall provide, at a minimum, an equivalent level of treatment and disposal as a conventional wastewater system. Alternative wastewater products will require the same documentation as above however, these will not require a Class C designer to incorporate into a design.
5.12.3 No person shall construct an alternative on‑site wastewater treatment and disposal system without obtaining a permit from the Department.
5.12.4 Applications for alternative systems shall be made to the Department. The application shall be complete, signed by the owner and accompanied by the required fee. The application shall include detailed system design specifications, plans and any additional information requested by the Department.
5.12.5 Applications for alternative on-site wastewater treatment and disposal systems shall include, but not be limited to, the following:
5.12.5.1 Volume and rate of wastewater flow
5.12.5.2 Characteristics of the wastewater
5.12.5.3 The degree and extent of treatment expected
5.12.5.4 Design criteria, specifications, and drawings including a description of the system, its capabilities, operation and maintenance requirements, unique technical features and system advantages for treatment systems
5.12.5.5 Construction materials
5.12.5.6 Operational and maintenance details along with their requirements
5.12.5.7 The seal of a Professional Engineer having a Class C license may be required
5.12.5.8 Any other information required by the Department
5.12.6 Sites may be considered for Alternative System Permits where:
5.12.6.1 Soils, climate, ground water, or topographical conditions are indicating the seasonal high water table or a limiting condition is encountered deeper than ten (10) inches below the soil surface or observation well data determines the seasonal high water table is deeper than ten (10) inches; and
5.12.6.2 A specific acceptable backup alternative is available in the event of system failure; and
5.12.6.3 Installation of a particular system is necessary to provide a sufficient sampling data base; and
5.12.6.4 Zoning, planning, and building requirements allow system installation; and
5.12.6.5 The system will be used on a continuous basis during the life of the project
5.12.7 The permit shall:
5.12.7.1 Specify method and manner of system installation, operation and maintenance;
5.12.7.2 Specify method, manner and duration of system testing and monitoring, at the Department’s discretion;
5.12.7.3 Identify when and where the system is to be inspected;
5.12.7.4 Require system construction and use within two (2) years of permit issuance
5.12.8 Inspection of all installed systems shall be performed by a Class C Designer and the Department. Upon completion of each phase requiring inspection by the permit, the Class E System Contractor shall notify the Department and the Class C Designer.
5.12.9 The Department may inspect construction at any time to determine whether it complies with permit conditions and requirements.
5.12.10 After system installation is complete and the Department has determined that it complies with permit conditions, a Certificate of Satisfactory Completion shall be issued.
5.12.11 If the Department finds the operation of the system is unsatisfactory, the owner, upon written notification by the Department shall promptly repair or modify the system, replace it with another acceptable system, or abandon the system.
5.12.12 The system will be monitored by the Department and/or the Department’s designee in accordance with a schedule contained in the permit.
5.12.13 Should any additional guidelines be developed by the Department, the permitee would be responsible for meeting these guidelines.
5.13 Community Systems
5.13.1 Without first applying for and obtaining a construction permit, no person shall install a community on‑site wastewater treatment and disposal system.
5.13.2 A community on-site wastewater treatment and disposal system shall be required when any of the following conditions exist:
5.13.2.1 Proposed number of lots is one hundred (100); or
5.13.2.2 Where overall density of the subdivision or planned unit development is more than one dwelling unit per ½ acre.
5.13.3 Applications for permits to construct community on-site wastewater treatment and disposal systems shall provide documentation which addresses ownership, transfer of ownership, maintenance, repairs, operation, performance and funding of the on-site wastewater treatment and disposal system through the design life of the system. This documentation shall be in the form of a Binding Agreement between the applicant for the construction permit, the "permittee", and an operator or owner/operator. The Binding Agreement must:
5.13.3.1 Identify an Operator or Operator and Owner (Operator) that will assume the operation, management, maintenance and repairs of the community on-site wastewater and disposal system, "the wastewater system", upon satisfactory completion of the construction, by providing:
5.13.3.1.1 Full name and business address of the Operator;
5.13.3.1.2 A description of the Operator’s experience, training and education in the wastewater treatment and disposal industry, together with any supporting data regarding the Operator’s qualifications in the industry;
5.13.3.1.3 Proof of the Operator’s financial solvency by providing a business financial statement (including balance sheet) that is not more than six (6) months old, and a statement of financial encumbrances;
5.13.3.1.4 A list of licensed wastewater treatment facility operators employed by the Operator
5.13.3.2 Identify the terms and conditions under which the Operator shall assume operational responsibility or ownership of the wastewater system.
5.13.3.3 Provide a detailed description of the wastewater system.
5.13.3.4 Disclose any existing encumbrances, liens or other indebtedness to the title of the wastewater system.
5.13.3.5 Provide an operating budget with sufficient funds for the proper operation and maintenance of the wastewater system, including the accumulation of funds necessary to provide for repair or replacement of mechanical components of the wastewater system based on manufacturer recommendation. The operating budget shall include the establishment of an escrow account to be used exclusively for repair and replacement of failed or failing components of the wastewater system. The escrow account may not be used for phasing construction or the expansion of the wastewater system to accommodate additional residential units.
5.13.3.5.1 The value of the escrow account shall be equivalent to 25% of the cost of all mechanical equipment (e.g., pumps, flow meters, aerators, blowers, gear boxes, etc.) plus 50% of the cost of construction of the wastewater treatment and disposal system (e.g., infiltration beds, trenches, etc.).
5.13.3.5.2 Funds shall be deposited into the escrow account as residential units are connected to the wastewater system. The amount of funds deposited shall be equivalent to the percentage of units connected to the wastewater system (i.e., at 50% of build-out, the balance of the escrow account shall equal 50% of the amount established in 1, above).
5.13.3.5.3 The escrow account shall be transferred to either the owner/operator or an established Homeowners Association upon satisfactory completion of construction of the wastewater system.
5.13.3.5.4 The owner of the wastewater system shall notify the Department, in writing, of intent to access funds from the escrow account. The escrow funds may not be used without prior approval of the Department. When escrow funds are used for the repair and/or replacement of mechanical equipment, the owner must submit a plan for the reestablishment of the escrow fund balance through the use of user fees or other sources.
5.13.3.5.5 The escrow account established for a community or a development can only be used for the community or development for which it was established. Accounts for non-contiguous communities or developments may not be co-mingled.
5.13.3.5.6 If the community wastewater system for which the escrow account was established is abandoned, and the community development connects to a regional or municipal wastewater treatment facility, the escrow account may be reduced to cover 25% of the replacement cost of all mechanical equipment associated with the transmission and conveyance sewer lines. If the transmission and conveyance sewer lines are all gravity lines, with no lift stations, pumps, or other mechanical equipment, the escrow account may be terminated and the funds returned to the wastewater system owner.
5.13.3.6 Be approved by the Department and fully executed before a construction permit is issued by the Department.
5.13.3.7 The Department shall have the right to inspect and review the financial records of the owner of the wastewater system, to include the operating budget, escrow account, and financial statements.
5.13.4 Prior to initiation of construction of any part or component of the community system the permittee shall provide the Department with an executed performance bond, irrevocable letter of credit, or other security, as approved by the Department, for every wastewater system they are constructing. The performance bond shall be made payable to the Department and the obligation of the performance bond shall be conditioned upon the fulfillment of all requirements related to the construction permit. Terms of the performance bond shall be:
5.13.4.1 The amount shall be equivalent to 50% of the construction cost of the wastewater system (excluding the conveyance system and its appurtenances), but in no case shall it be less than $25,000 nor more than $100,000 for any single community system.
5.13.4.2 A performance bond is not required for any local, municipal, county, state, federal government agency, non-profit association representing property owners, political subdivision, or utility that is regulated by the Public Service Commission.
5.13.4.3 Liability under the performance bond shall run to the State for a continuous period. The Department shall release the bond only after the wastewater system has been constructed in accordance with approved plans and has been turned over to an established homeowners association, their designee, or exempted trustee identified in §5.13.4.2 above, provided the requirements of §5.13.4.7 are met.
5.13.4.4 The performance bond shall be executed by the permittee through a corporate surety licensed to do business in the State of Delaware. In lieu of a performance bond, the permittee may elect to provide an original irrevocable letter of credit equal to the required sum of the performance bond.
5.13.4.5 The obligation of the permittee under the performance bond shall become due and payable for the purposes of properly fulfilling the requirements of the permit when the Department has:
5.13.4.5.1 Notified the permittee that the conditions of the permit have not been fulfilled and specified the specific deficiencies in the fulfillment of the permit conditions;
5.13.4.5.2 Given the permittee a reasonable opportunity to correct the deficiencies and to fulfill all the conditions of the permit; and
5.13.4.5.3 Determined that, at the end of a reasonable length of time, some or all of the deficiencies specified under §5.13.4.5.1 above remain uncorrected.
5.13.4.6 The Department has the authority to designate a new Operator in the event that the provisions of §5.13.4.5 have been implemented. Upon formal transfer of ownership of a community wastewater system to an entity identified in §5.13.4.2, the performance bond requirement shall cease, provided the Department has determined that the wastewater system has been constructed in accordance with approved plans and is operating properly.
5.13.4.7 Once the Department has verified that the wastewater system has been constructed in accordance with approved plans, the owner may apply for a permit to operate the system.
5.13.5 The permit application shall also include the following documents for legal review by the Department;
5.13.5.1 A Purchase and Sale Agreement which specifies that the purchaser or a dwelling unit has an encumbrance on the title for wastewater treatment and disposal system operation fees, easements, and other assessments related to the community system.
5.13.5.2 An Acknowledgment of Buyer which is appended to the Purchase and Sale Agreement and signed by the buyer after being furnished copies of appropriate agreements, covenants, restrictions, Articles of Incorporation and Bylaws of the Owners’ Association, and indicates understanding that the buyer is obligated to pay assessments for maintaining the community system.
5.13.5.3 The Articles of Incorporation which establishes the owner's association as a state‑chartered, nonprofit corporation and gives the owners' association specific authority to operate, maintain, and repair the community system; to collect fees and special assessments; and to enforce any covenants, restrictions, or agreements.
5.13.5.4 The Bylaws of the Owners' Association which govern the operation of the owners' association and specifically authorizes the Board of Directors to supervise the operation and maintenance of the community system, collect fees and special assessments, and to take appropriate action when the public health is imperiled by the malfunctioning of the community system.
5.13.5.5 A Declaration of Covenants, Restrictions, and Easements which establishes, among many other limitations, the easements for the on‑site sewage collection, treatment, and disposal system, and specifies responsibilities of the developers, their successors or assigns, and any owners' association regarding the community system. It further sets the fees and assessments for operation and maintenance of the community system.
5.13.6 For developments that do not contain homeowners’ associations, the above list of documents may be modified, at the Department’s discretion, to include only those documents that are applicable.
5.13.7 All community systems that are owned solely by one owner, partnership or corporation, who own the property that the system will be installed on must execute a Declaration of Covenants, Restrictions and Easements (DCR). The DCR must be notarized and recorded at the County’s Office of the Recorder of Deeds after it has been approved by the Department. The recorded copy should then be returned to the Department. Community systems meeting this requirement shall be exempt from §§5.13.3, 5.13.4 and 5.13.5.
5.13.8 The site criteria for approval of community systems shall be the same as required for large systems (see §5.14).
5.13.9 Responsibility for operation and maintenance of community systems shall be vested in a governmental unit or a Council on behalf of the unit property owners pursuant to 25 Del.C. Ch. 22 or for subdivisions with an owners' association duly incorporated within the State with specific authority to operate, maintain, and repair the community system, to collect fees and special assessments and to enforce any covenants, restrictions or agreements (see §5.13.4).
5.13.10 Unless otherwise required by permit, community systems shall be inspected, at least annually, by the responsible person.
5.13.11 A private wastewater utility corporation may be permitted subject to the following provisions:
5.13.11.1 It must be duly incorporated within the State and remain in good standing.
5.13.11.2 It must remain financially solvent on a continuous basis through a method of financing construction, maintenance, operation, and emergency work related to the community system to the exclusion of whatever other obligations the corporation may assume in other fields. A certification of compliance with this provision shall be provided to the Department annually.
5.13.11.3 There must be a person as identified under §5.13.8 to whom control and operation of the community system will pass in trusteeship in the event no persons are willing to serve as officers of the private utility corporation. Such person shall have the opportunity to review and comment on plans and specifications and perform inspections during construction. They shall also be notified of any future construction or major repairs.
5.13.11.4 Funds collected for operation and maintenance of the system must be kept in an account to be used for the sole purpose of carrying out the functions of the community system.
5.13.11.5 There shall be lien powers to assure the collection of delinquent debts.
5.14 Large Systems
5.14.1 Unless otherwise authorized by the Department, all soils and siting criteria for large systems shall comply with the following requirements:
5.14.1.1 A Soil Investigative Report (SIR) shall be filed with the Department’s Large Systems Branch setting forth the proposed manner of compliance with these Regulations. The SIR shall contain the following:
5.14.1.1.1 Site plan drawn to scale not to exceed one (1) inch equals two hundred (200) feet
5.14.1.1.2 A topographic map with two (2) foot contour intervals unless the Department approves the use of an alternate scale
5.14.1.1.3 Location of all wells, watercourses, roads and on-site wastewater treatment and disposal systems within one hundred fifty (150) feet of the perimeter of the property
5.14.1.1.4 The proposed disposal area shall be mapped on a grid pattern of not more than seventy five (75) feet between observations using a combination of auger borings and test pits
5.14.1.1.5 A description of the hydrologic properties of the water table/surficial aquifer, including estimates of horizontal and vertical hydraulic conductivity, ground water flow direction, and water table elevations or depth to water table measurements. This information can be obtained from readily available published data.
5.14.1.1.6 A representative number of infiltration tests (minimum single-ring) shall be conducted within the proposed disposal area (PDA), based upon soil variability. These tests must be performed within the most restrictive horizon per mapping unit within the PDA.
5.14.1.1.7 Determination of an appropriate design percolation rate based upon infiltration tests, soil characteristics (textures, structure, etc.) and number of mapping units within the PDA (Certain site specific conditions may not warrant the testing, contact the Department to discuss)
5.14.1.1.8 Depth of the limiting zone and the results of the site and soil analysis provided on the appropriate forms (i.e. Approval page)
5.14.1.1.9 Number of proposed lots, dwellings or expected gal/day flow and loading rate
5.14.1.1.10 The preliminary plan shall include a general site location map to identify the area
5.14.1.1.11 The location of any jurisdictional wetlands (State and/or Federal), if delineated
5.14.1.1.12 Identification of any limitation that could affect system performance and design consideration
5.14.1.1.13 The Department shall approve the SIR after any and all concerns have been addressed
5.14.1.2 The applicant shall provide a Preliminary Groundwater Impact Assessment (PGIA). The PGIA shall assess the potential impact of the large system upon waters of the State and upon public health. The PGIA shall comply with current guidelines established by the Department.
5.14.1.3 Performance of wet season testing (December – May) to more accurately quantify the fluctuations of the water table may be required on a case by case basis as warranted by site conditions. (This is recommended during the planning stages of the project.) If rainfall is not normal (see definition in §5.2.1.7) a second season of monitoring may be required. If timing does not allow for the testing prior to submittal, contact the Department.
5.14.1.4 Ground-water mounding analysis may be required for proposed large on-site wastewater treatment and disposal system sites where a potential for significant water-table mounding is probable due to (1) low aquifer transmissivity (low hydraulic conductivity), (2) shallow depth to seasonal high water table, or (3) high wastewater loading rate. Slug test(s) may be necessary to obtain horizontal hydraulic conductivity values for the aquifer. A report documenting the ground-water model utilized to perform the analysis must be provided along with all aquifer parameters and design criteria needed to run the model. Only Certified Professional Geologists registered in the State of Delaware are qualified to perform the ground water mounding analysis.
5.14.2 Prior to permit application submission, the SIR and PGIA must both be approved and a meeting with the Class D Soil Scientist, Class C Designer, Department personnel and any other interested parties be held to discuss the project.
5.14.3 Unless otherwise authorized by the Department, all treatment and design considerations for large systems shall comply with the following requirements:
5.14.3.1 Permit applications must be designed in accordance with the prescribed system type and design considerations as specified in the SIR and PGIA for that parcel.
5.14.3.2 All permit application(s) for a large system (> 2,500 GPD) shall be submitted to the GWDS, Large Systems for review and approval.
5.14.3.3 Large system absorption facilities shall be designed with pressure distribution.
5.14.3.4 The disposal system shall be divided into relatively equal areas. For effluent distribution each area is comprised of units as follows. The length to width ratio for seepage beds and elevated sand mounds shall be 4 : 1 or greater. Each unit shall receive no more than one thousand three hundred (1,300) GPD if seepage beds are utilized and no more than two thousand six hundred (2,600) GPD if seepage trenches are utilized. The Department has sole discretion to deviate from this requirement if site constraints warrant such deviation.
5.14.3.5 The replacement (repair) disposal area shall be divided into relatively equal units and sufficient replacement area must exist. Upgrading the initial system(s) will not suffice as replacement area.
5.14.3.6 Effluent distribution shall alternate between the disposal area units. The absorption facilities shall be at least ten (10) feet apart.
5.14.3.7 Each system shall have at least two (2) pumps or siphons.
5.14.3.8 Large systems treating domestic wastes which utilize conventional septic tank treatment shall be required to install an effluent filter following the primary treatment.
5.14.3.9 Large systems shall be designed with a means to measure wastewater flow. Flow data will be recorded and reported to the Department by the licensed operator in accordance with the permit requirements.
5.14.3.10 Expected flows > 20,000 GPD shall incorporate secondary wastewater treatment as approved by the Department.
5.14.3.11 The Department may require additional information beyond the scope presented here on a case by case basis.
5.14.3.12 Any on-site wastewater treatment and disposal system receiving over two thousand five hundred (2,500) GPD will require a licensed wastewater operator. The class of operator will be determined based on the Board of Certification for Licensed Wastewater Operators.
5.14.3.13 Prior to installing the wastewater treatment and disposal system, a meeting with the Class D Soil Scientist, Class C Designer, Class E System Contractor, Department personnel and any other interested parties shall be held to discuss the project.
5.14.4 Unless waived by the Department, groundwater monitoring is required at all sites utilizing large on-site wastewater treatment and disposal systems. Such monitoring shall continue as long as required by the Department. Upon completion of the PGIA review, the Department may require the submittal of a monitoring plan. If monitoring is required, a minimum of three (3) monitor wells, one up gradient and two down gradient from the proposed disposal areas must be installed and surveyed.
5.14.5 If, after review of the PGIA, the Department determines that there is a potential for significant adverse impact to the environment or public health, a more detailed Groundwater Impact Assessment (GIA) may be required.
5.15 Holding Tanks
5.15.1 The use of a holding tank is an unusual circumstance wherein all wastewater is permitted to be held in a watertight structure until it is pumped and transported by vehicle to a point of disposal. The use of a holding tank on a permanent basis is prohibited except as provided in these Regulations.
5.15.2 Permanent holding tanks are not permitted on unimproved lots.
5.15.3 No person shall install a holding tank without first obtaining a permit from the Department.
5.15.4 All holding tank permit applications and designs must be completed by a Class C Designer.
5.15.5 Permits may be issued, by the Department, for the permanent use of holding tanks when all of the following conditions are met:
5.15.5.1 The site is improved with a dwelling and has been evaluated for all means of on-site wastewater treatment and disposal, including alternative technologies, and has been deemed not suitable for an on-site wastewater treatment and disposal system; and
5.15.5.2 No community or area‑wide central wastewater system is available or expected to be available within five (5) years; and
5.15.5.3 The same isolation distances as required for septic tanks can be met; and
5.15.5.4 The owner(s) enter into a contract with a licensed Class F Liquid Waste Hauler to provide hauling services to the dwelling for the period it is utilized or until connection can be made to an approved wastewater facility. Should the owners change waste haulers, a new contract shall be submitted to the Department; and
5.15.5.5 The property deed shall be amended with an Affidavit of Ownership at the time of permit issuance, which states that the dwelling is served by a permanent holding tank. The Affidavit of Ownership must be recorded at the Recorder of Deeds; and
5.15.5.6 When the governmental unit or wastewater utility provides the hauling services directly, it shall conform to the requirements for liquid waste haulers; and
5.15.5.7 Have a water meter installed to measure the in-flow of water into the building or house or a metering device measuring the flow to the tank
5.15.6 In an area under the control of a governmental unit, or a wastewater utility which has a recorded covenant with the owner that runs with the land, either of which is authorized to construct, operate, and maintain a community or area‑wide central wastewater system, a holding tank may be installed for temporary use provided:
5.15.6.1 The application for permit includes a copy of a legal commitment from the governmental unit or wastewater utility that within five (5) years from the date of application the governmental unit or wastewater utility will extend to the property covered by the application, a community or area‑wide central wastewater system meeting the requirements of the Department; and
5.15.6.2 The community or area‑wide central wastewater system has received the necessary approvals for full operation (established sewer district) which includes the anticipated flow to the holding tank; and
5.15.6.3 The proposed holding tank will comply with the requirements of these Regulations.
5.15.7 Temporary use of a holding tank may be approved when:
5.15.7.1 Installation of an approved on‑site system has been delayed by weather conditions; or
5.15.7.2 The tank is to serve a temporary construction site (up to five (5) years).
5.15.8 Applications for holding tank installation shall contain plans and specifications in sufficient detail for each holding tank proposed to be installed and shall be submitted to the Department for review and approval. The application for a permit shall be on forms provided by the Department and contain the following items:
5.15.8.1 A copy of a contract with a licensed liquid waste hauler shall contain, as a minimum, the following conditions:
5.15.8.1.1 Duration of contract;
5.15.8.1.2 Pumping schedule;
5.15.8.1.3 Availability of equipment;
5.15.8.1.4 Emergency response capability;
5.15.8.1.5 Contents will be disposed of in a manner and at a facility or location approved by the Department;
5.15.8.1.6 Evidence that the Owner or Operator of the proposed disposal facility will accept the pumping for treatment and disposal;
5.15.8.1.7 Method of measuring wastewater use (water meter, wastewater meter, etc.)
5.15.8.2 A record of pumping dates and the amounts pumped shall be maintained by both the property owner and the liquid waste hauler, and be made available to the Department along with in-flow meter readings as part of the annual renewal of the permit.
5.15.8.3 The appropriate annual inspection fee
5.15.9 Each holding tank shall:
5.15.9.1 In no case shall the tank have a capacity less than seven (7) days average flow from the wastewater generating facility or 1,000 gallons, whichever is larger. When holding tanks are designed to serve the needs of a community system, the size shall be in conformance with standard engineering practice as determined by the Department and in accordance with an acceptable monitoring and pumping schedule.
5.15.9.2 Comply with standards for septic tanks as prescribed in these Regulations (see §6.0700).
5.15.9.3 Be located and designed to facilitate removal of contents by pumping.
5.15.9.4 Be equipped with both an audible and visual alarm installed on an AC circuit and placed in a location, acceptable to the Department, to indicate when the contents of the tank are at seventy-five percent (75%) of capacity.
5.15.9.5 Have no vent at an elevation lower than the overflow level of the lowest fixture served.
5.15.9.6 Be designed for anti-buoyancy if test hole examination or other observations indicate that seasonally high groundwater may float the tank when empty.
5.15.9.7 Be constructed of the same materials approved for septic tanks. Holding tanks shall be watertight and structurally sound to withstand internal and external loads.
5.15.9.8 Be equipped with an eighteen (18) inch diameter or square access opening. The access opening shall be extended to a minimum of six (6) inches above grade level.
5.15.9.9 All tanks constructed on-site (i.e. cast-in-place, concrete block, etc.) shall be tested to assure watertight conditions. Alarms shall be tested for proper operation.
5.15.10 Each holding tank installed under these Regulations shall be inspected annually. A fee shall be charged for each annual inspection and all required documentation shall be submitted also.
5.15.11 No liquid waste from a holding tank shall be applied directly or indirectly onto the ground surface or into surface waters.
5.15.12 Prior to purchase of a dwelling that is currently served by a holding tank or is proposed to be served by a holding tank, the prospective buyer must sign an Affidavit of Understanding of the terms and conditions associated with use of a holding tank. This Affidavit shall be submitted to the Department to be filed with the permit.
5.16 Moratorium Areas
5.16.1 As soon as the Department determines that construction of on-site wastewater treatment and disposal systems should be limited or prohibited in an area, it shall issue an order limiting or prohibiting such construction.
5.16.2 The order shall be issued only after a public hearing which shall insure that twenty (20) days notice is given.
5.16.3 The order shall contain a specific description of the moratorium area and shall be limited to the area immediately threatened with ground water or surface water contamination if construction in that area continues.
5.16.4 In issuing an order under this Section the Department shall consider the factors contained in 7 Del.C. Ch. 60, §6001.
5.16.5 The moratorium shall be limited to a period of five (5) years after which re-establishment of the moratorium may be considered.
 
6.0 Design and Construction
6.1 General Requirements
6.1.1 Location: All on-site wastewater treatment and disposal systems shall be located according to the minimum horizontal isolation distances specified in these Regulations (see Exhibit T). All isolation distances for capped systems and elevated sand mounds shall be measured from the edge of the aggregate or aggregate-free chamber.
6.1.2 All pressurized systems must be constructed in such a manner that the operating pressure can be checked at the end of the distal lateral (permanent tee, etc).
6.1.3 All pressurized systems must utilize timers or other electrical on/off delay devices to insure dosing frequencies.
6.2 Disposal System Sizing
6.2.1 All on-site wastewater treatment and disposal systems shall be sized based on the estimated wastewater flow and the results of percolation tests or the assigned percolation rate. Percolation rates shall be based on USDA soil textures and assigned by the Class D Soil Scientist. The table of percolation rates used by the Department (see Exhibit W) does not assign rates, it gives estimates based upon textures. Percolation rates of less than 20 minutes per inch (mpi) will not be allowed for designing any on-site wastewater treatment and disposal system, unless otherwise approved by the Department.
6.2.2 The minimum disposal area required for trench systems with percolation rates less than 120 mpi shall be determined from the following equation:
A = 0.33 Q (t)0.5
Where
A = the minimum disposal area required in square feet
Q = wastewater application rate in gallons per day
t = the average percolation rate in minutes per inch (minimum
rate is 20 mpi for design)
6.2.3 The minimum disposal area required for seepage bed systems with percolation rates less than 120 mpi shall be determined from the following equation:
A = 0.42 Q (t)0.5
where
A = the minimum disposal area required in square feet
Q = wastewater application rate in gallons per day
t = the average percolation rate in minutes per inch (minimum
rate is 20 mpi for design)
6.2.4 Where percolation rates are faster than 6 mpi, such as in soils with USDA textures of sands, and loamy sands, a pressurized distribution system is required; the minimum disposal area shall be determined from the following equation:
A = 1.2 Q
Where:
A = the minimum disposal area required in square feet
Q = design flow rate in gallons per day
6.2.5 The minimum disposal area required for low-pressure pipe systems with percolation rates less than 120 mpi shall be determined from the following equation:
A = UQ
Where:
A = the minimum disposal are required in square feet
Q = design flow rate in gallons per day
U = unit absorption area (see Exhibit X)
6.3 Excavation
6.3.1 Clearing and Grubbing: All vegetation shall be cut and removed from the grade surface at a distance of ten (10) feet beyond the perimeter of the disposal area. Trees and shrubs shall be cut and removed at grade level while roots may be left in place. All cut materials shall be removed from the disposal area.
6.3.2 Special care should be taken when clearing vegetation from an approved disposal area as disturbance of the soil surface may render the site unsuitable.
6.3.3 All unsuitable excavation materials shall be discarded and the excavation shall be kept dry and de-watered from surface drainage until backfilling is completed.
6.3.4 Excavation machinery shall be of such type and operated in such a manner that they will not compact or smear the trench or bed sidewall soils. If smearing does occur, the smeared surfaces shall be hand raked to expose an unsmeared soil interface. Trenchers are preferred for excavation of LPP trenches.
6.3.5 Excavations below the design depth shall be brought up to proper elevation with approved fill materials installed in accordance with these Regulations and the requirements for sand‑lined systems. Additional aggregate may only be used when a minimum of three (3) feet of undisturbed soil can be maintained between the bottom of the aggregate and the limiting zone. In no case shall more than one (l) foot of additional aggregate be used.
6.3.6 The sides of the trenches or beds shall be practically plumb and scarified.
6.3.7 The bottom of the trench or bed area shall be practically level as determined by using a transit, or laser level, with a maximum grade tolerance of two (2) inches per one hundred (100) feet.
6.3.8 All trench or bed excavations shall be kept free of water and dry. Tamping of trench sides and bottoms is not permitted.
6.4 Materials
6.4.1 Sandy fill materials shall be medium sand, sandy loam, loamy sand/sandy loam mixture. The fill material shall have the following characteristics:
 
 
6.4.2 Filter aggregate must come from a supplier approved by the Department. Storage and cleaning procedures must be approved by Department before supplier can be included on approved list. Random inspection of supply pits and supplier’s storage facilities shall be performed by the Department.
 
 
Note: The Class E System Contractor shall submit upon request a Certification of Materials for fill and aggregate used in systems. This certificate shall be obtained from the supplier.
 
6.4.3 Grade boards or blocks may be used in pipe installation to assure a proper slope of less than two (2) inches per one hundred (100) feet for gravity distribution lines.
6.4.4 Filter fabric shall be placed over the gravel with a two (2) inch overlap turned up on each side of the trench or bed.
6.4.5 Aggregate-free chambers or any other similar devices may be used in the design, installation, and operation of on-site wastewater treatment and disposal systems in Delaware, but are subject to approval of the Department. The minimum disposal area required when using aggregate-free chambers shall be calculated by utilizing the most recent guidelines and §§6.2.2 and 6.2.3.
6.5 Distribution Networks
6.5.1 All systems requiring a total of more than 2,500 square feet of disposal area shall have a pressurized distribution system pursuant to these Regulations.
6.5.2 All systems requiring more than 2,500 square feet of disposal area, with the exception of low pressure pipe systems, shall be divided into a minimum of two separate alternating systems of equal size with pressurized distribution provided alternatively to each system. The minimum separation between absorption facilities shall be ten (10) feet, which, with the exception of subsurface irrigation systems, will be determined on a case by case basis.
6.5.3 All systems installed on lots where percolation rates are faster than six (6) mpi shall have pressure distribution systems.
6.5.4 A minimum distance of four (4) feet and a maximum distance of six (6) feet shall separate adjacent laterals in a bed. Laterals shall be placed no farther than three (3) feet from the sidewalls of the bed. The length to width ratio for seepage beds and elevated sand mounds shall be 4 : 1 or greater and maximum bed width shall not exceed twenty five (25) feet, unless approved by the Department. A minimum distance of six (6) feet shall separate laterals in a trench disposal system.
6.5.5 Gravity system distribution laterals may be connected in closed loop systems.
6.5.6 The maximum allowable lateral length is one hundred (100) feet for gravity distribution systems and pressure distribution systems.
6.5.7 Each trench or bed system shall contain at least two (2) distribution laterals. Trenches shall be utilized in all distribution systems located on slopes in excess of two (2) percent, unless otherwise approved by the Department.
6.5.8 All distribution systems shall ensure equal distribution when designed on slopes.
6.6 Conventional Treatment and Disposal Systems
6.6.1 Gravity Trenches and Beds (see Exhibits K, L, M and N)
6.6.1.1 A minimum of twelve (12) inches of filter aggregate shall be placed in the bed or trench. A minimum of six (6) inches of aggregate shall be placed under the distribution laterals. The remaining filter aggregate shall be placed so that a minimum depth of no less than two (2) inches exists above the crown of the distribution pipe.
6.6.1.2 For trenches or beds with a minimum sidewall depth of twenty‑four (24) inches, backfill shall be placed in accordance with permit requirements. Unless otherwise required by the Department, the construction sequence shall be as follows:
6.6.1.2.1 The backfill material shall be at least twelve (12) inches in depth above the filter fabric and returned to the original grade.
6.6.1.2.2 Backfill material shall be carefully deposited by methods which will not damage or disturb the distribution pipe or result in undue compaction of the backfill.
6.6.1.2.3 Backfill over trenches or beds shall not be tamped.
6.6.1.2.4 Material containing an excess of moisture shall be permitted to dry until the moisture content is within workable limits. The moisture content of the material being placed shall be within plus or minus 3% of optimum as determined by AASHTO Designation T‑ 99.
6.6.1.2.5 Backfill material which is too dry for proper placement shall be wetted. All materials shall be free of stones larger than two (2) inches in diameter, debris, trash, wood or other similar materials.
6.6.1.3 For trenches or beds with a minimum sidewall depth of twelve (12) inches but less than twenty‑four (24) inches, a capping fill shall be placed over the disposal system. The cap shall be constructed pursuant to permit requirements (see Exhibits M and N). Unless otherwise required by the Department, the construction sequence shall be as follows:
6.6.1.3.1 The texture of the soil used for the cap shall be of the same textural class or of one textural class finer, as the natural topsoil. All materials shall be free of stones larger than two (2) inches in diameter, debris, trash, wood or other similar materials.
6.6.1.3.2 Construction of capping fills shall not occur when the natural soil has a moisture content which causes loss of soil structure and porosity when worked.
6.6.1.3.3 The disposal area shall be scarified to destroy the vegetative mat.
6.6.1.3.4 The system shall be installed as specified in the construction permit. There shall be a minimum of ten (10) feet of separation between the edge of the fill and the absorption facility.
6.6.1.3.5 Suitable backfill shall be applied to the fill site and worked in so that the two (2) contact layers (native soil and fill) are mixed. Fill material shall be evenly graded to a final depth of sixteen (16) inches over the aggregate.
6.6.1.3.6 The site shall be landscaped according to permit conditions and be protected from livestock, automotive traffic or other activity that could damage the system.
6.7 Sand Mounds (see Exhibit P)
6.7.1 Sand mound absorption areas shall be plowed six (6) to eight (8) inches deep parallel to the contour after removing the vegetative mat. Plowing shall not be done on wet soils. No plowing instruments which compact the soil shall be used. Moldboard or chisel plows are recommended.
6.7.2 Immediately after plowing, sandy fill shall be placed on the up-slope edges of the plowed mound absorption area and spread to a depth as specified in the permit. Only lightweight equipment such as small track type tractors shall be allowed.
6.7.3 A twelve (12) inch bed of filter aggregate shall be placed over the sand fill. Six (6) inches of aggregate shall be placed under the distribution lateral. The remaining filter aggregate shall be placed to an additional six (6) inches in depth with at least two (2) inches over the crown of the distribution pipe.
6.7.4 A minimum allowable distance of four (4) feet and a maximum distance of six (6) feet shall separate adjacent laterals in a elevated sand mound bed.
6.7.5 The slope of the sand fill not directly beneath the filter aggregate shall be 3 : 1, with 5 : 1 recommended by the Department.
6.7.6 Mound covering or berm soil shall be loamy sand or sandy loam.
6.7.7 The mound berm shall extend at least twelve (12) inches above the twelve (12) inch filter aggregate layer plus at least six (6) inches of topsoil cover.
6.7.8 The outside slopes of the mound cover or berm shall be approximately 3 : 1 with 5 : 1 recommended by the Department.
6.7.9 Erosion control shall be provided over the complete mound in one of the following manners:
6.7.9.1 Grass shall be planted over the entire mound and stabilized with mulch; or
6.7.9.2 Sod entire mound; or
6.7.9.3 Other pre-authorized methods of erosion control
6.8 Low Pressure Pipe Systems (see Exhibits O & X)
6.8.1 A trench width of twelve (12) inches shall be used.
6.8.2 Trenches shall be no less than five (5) feet on center.
6.8.3 There shall be six (6) inches of aggregate below the pipe and two (2) inches of aggregate above the pipe. There shall be a minimum of six (6) inches and a maximum of nine (9) inches of soil cover.
6.8.4 Filter fabric shall be placed on top of the aggregate in the trench with a two (2) inch overlap turned up on each side of the trench.
6.8.5 Check valves are required to eliminate the back siphoning of effluent from the laterals.
6.8.6 Turn ups or cleanouts shall be finished below grade and protected by a four (4) inch diameter or greater Sch. 40 PVC sleeve with a cap and ferrule finished at grade.
6.8.7 Timers or other electrical on/off delay devices shall be installed to insure dosing frequencies.
6.9 Site Restoration:
6.9.1 The finished grade of the backfill over seepage bed, trench and sand-lined absorption facilities shall be sloped to provide positive drainage.
6.9.2 The land adjacent to all absorption facilities shall be graded to prevent both the accumulation of surface water on the absorption facility and the flow of surface water across the absorption facility. The finished absorption facility and fill extensions shall be seeded and mulched to prevent erosion.
6.9.3 Trees shall not be planted within ten (10) feet of the perimeter of absorption facility. All trees and shrubs shall be located to prevent root intrusion into the absorption facility and other components of the system. Shallow rooted shrubs are permitted (i.e. rhododendrons, azaleas, etc.)
6.9.4 All areas of disturbance due to the installation of the absorption facility shall be either sodded or seeded and mulched to establish a permanent grass cover.
6.10 Spare Area
6.10.1 Each site utilizing an on‑site wastewater treatment and disposal system shall have sufficient area to accommodate a complete replacement system or an acceptable alternative approved by the Department which satisfies the requirements of these Regulations. This area shall be maintained so that it is free from encroachments by accessory buildings and additions to the main building. Encroachment shall include the ten (10) foot isolation distance to buildings as required by these Regulations. This requirement may be waived if the application for a permit includes a copy of a legal commitment from the governmental unit that states that within five (5)years from the date of the application the governmental unit will extend to the property a community or area‑wide central wastewater system meeting the requirements of the Department or an acceptable alternative is approved by the Department. The community or area‑wide central wastewater system has received the necessary approvals for full operation which includes the anticipated flow to the on‑site wastewater treatment and disposal system.
6.11 Artificially Drained Systems
6.11.1 Disposal systems shall not be constructed on sites where curtain drains, vertical drains, underdrains, or similar drainage methods are utilized to artificially lower the level of the water table to meet the requirements of these Regulations. Observation wells may be used to demonstrate the change in the hydrology of a particular property for the purpose of siting an on-site wastewater treatment and disposal system.
6.12 Soil Percolation Rate Determination
6.12.1 Percolation rates are assigned by State environmental scientists and Class D Soil Scientists based upon observed soil structure and textures during the site evaluation. The Department has established percolation rates based upon USDA soil textures (see Exhibit W).
6.13 Soil Percolation Test
6.13.1 The soil percolation test shall provide a measure of the rate at which water moves from an uncased bore hole into the surrounding soil under nearly constant head in both vertical and horizontal directions.
6.13.2 One soil percolation test shall consist of three (3) test holes.
6.13.3 The percolation test shall be performed only after a site evaluation has indicated that the soil may be suitable for an on‑site wastewater treatment and disposal system. The percolation test shall be used to determine the rate at which wastewater effluent can be expected to seep into the soil. This rate shall be used in conjunction with a projected daily flow rate to determine the area required for proper treatment and disposal.
6.13.4 The depth of the percolation test holes shall not be determined until a site evaluation is completed and a limiting zone, if any, is identified. The depth of the percolation test holes shall be as follows:
6.13.4.1 If the limiting zone occurs at least twenty (20) inches from the soil surface, the percolation test holes shall be within the soil horizon that is controlling the water movement vertically and/or horizontally to a depth of sixty (60) inches.
6.13.4.2 If the limiting zone occurs at less than twenty (20) inches from the surface, the site is unsuitable for a conventional on‑site wastewater treatment and disposal system. However, if replacing a failing or malfunctioning system, item should be used without regard for the twenty (20) inch limiting condition. In situations where sand-lining through an impermeable or less permeable horizon within the top forty eight (48) inches, a percolation test should be performed within the soil zone which is controlling the water movement vertically and/or horizontally beneath the restrictive material to a depth of sixty (60) inches.
6.13.5 The following procedures shall be used for percolation tests:
6.13.5.1 A minimum of three (3) test holes shall be dug within the proposed installation area of the absorption facility. Additional tests may be required in areas with varying soil characteristics or when warranted at the sole discretion of the Department due to the size of the required disposal area.
6.13.5.2 Test holes with a horizontal diameter of six (6) inches shall be dug or bored. A post hole digger, auger or mechanical digger may be used to dig the holes.
6.13.5.3 The bottom and sides of each test hole shall be scarified to remove any smeared soil surfaces that result from digging. Loose soil shall be removed from the hole. Two (2) inches of coarse sand or fine aggregate shall be placed in the bottom of the hole to prevent sealing of the hole bottom when water is added.
6.13.5.4 The hole shall be filled with water to a minimum depth of twelve (12) inches above the aggregate or sand. This level shall be maintained for a period of at least four (4) hours.
6.13.5.5 The water level shall then be adjusted to six (6) inches over the gravel or sand. The hole shall be allowed to stand undisturbed for thirty (30) minutes. The water level shall again be adjusted to six (6) inches over the aggregate and the hole allowed to sit undisturbed for another thirty (30) minutes.
6.13.5.6 Where the drop in the water level is two (2) inches or more in thirty (30) minutes, the interval for readings during the percolation test shall be ten (10) minutes. Where the drop in the water level is less than two (2) inches in thirty (30) minutes, the interval for readings during the percolation test shall be thirty (30) minutes. The drop in water level shall be recorded after each reading and the water level shall be adjusted to six (6) inches above the gravel. Readings shall continue for a minimum of four (4) hours where the interval between readings is thirty (30) minutes. Where the interval is ten (10) minutes due to fast percolation, the readings may be discontinued after one (l) hour. Where the drop between readings has not stabilized at the end of the minimum period, the reading shall continue until a steady rate is established. A steady rate is established when two (2) successive water level drops do not vary by more than one-sixteenth (1/16) of an inch. If any of the holes has a rate that is significantly different from the other holes, it shall be examined to see if this hole is in a soil that is different from the soil described in the site evaluation. If the hole is determined, by the licensed Class A Percolation Tester, to be uncharacteristic of the site it shall be excluded from analysis but listed on the application.
6.13.5.7 The percolation rate for the site shall be determined by taking the arithmetic average of all percolation tests conducted. Percolation rates slower than one hundred twenty (120) minutes per inch (mpi) are unacceptable and shall not be used to determine the arithmetic average percolation rate but shall be reported. On‑site wastewater treatment and disposal systems shall not be placed on those portions of any sites that have percolation rates slower than one hundred twenty (120) mpi.
6.14 Additional Methodologies
6.14.1 At the discretion of the Department or Class D Soil Scientist, additional methodologies may be preferred as a substitute for the soil percolation test. Approved test methods are given in the current edition of Methods of Soil Analysis, ASA and the ASTM Standards.
6.15 Wastewater Design Flow Rates
6.15.1 The projected peak daily wastewater flow shall be used to determine the appropriate size and design of both, on‑site and community, wastewater treatment and disposal systems.
6.15.2 Where actual calibrated metered flow data indicating peak daily flows over the most recent three (3) year period are available for a similar facility, such peak flow data may be substituted for the wastewater flows listed in this Section subject to the approval of the Department. When ranked in descending order the adjusted design daily flow shall be determined by taking the numerical average of the daily readings within the upper ten (10) percent of the daily readings.
6.15.3 The design wastewater flow from residential dwellings, including single family, multiple family, manufactured homes, and apartments served by individual on‑site or community wastewater treatment and disposal systems shall be 120 gallons per day per bedroom. The minimum design flow for any commercial property shall be 120 gallons per day and residential dwelling shall be 240 gallons per day. Credit for water conservation devices will be accounted for according to current Department guidelines.
6.15.4 The design wastewater flow from other residential, commercial and/or institutional facilities served by individual on‑site or community systems shall be as prescribed in Exhibit D.
6.15.5 Disposal systems shall be designed to receive all wastewater, except for water softener brine, from the building or structure served unless otherwise approved by the Department.
6.15.6 All restaurants or other establishments involved in food preparation activities shall install external grease traps as required by the Department.
6.15.7 Laundromat and car wash wastewater shall be pretreated as specified by the Department prior to discharge to any absorption facility under these Regulations.
6.15.8 Industrial wastewater shall not be discharged into a septic tank unless prior approval is obtained from the Department.
6.16 Isolation Distances
6.16.1 The minimum isolation distances set forth in Exhibit C shall be maintained when designing, locating, constructing, repairing, replacing, and installing individual on‑site and community wastewater treatment and disposal systems.
6.16.2 The Department may require greater isolation distances for systems when conditions warrant for purposes of protecting environmental resources and the public health.
6.16.3 Isolation distances may be decreased by the Department based on a site specific geological and hydrogeological analysis performed pursuant to the requirements of these Regulations, provided that the Department is satisfied that such decrease will allow for protection of environmental resources and the public health.
6.16.4 Existing on‑site wastewater treatment and disposal systems which are repaired or replaced shall be subject to the requirements of this Section, provided however, that if it is impossible to comply with such requirements due to lot size limitations, the repaired or replaced system shall conform to the maximum extent practicable with the requirements of this Section as determined by the Department in its sole discretion.
6.17 Conventional On-Site Wastewater Treatment and Disposal Systems Criteria
6.17.1 All Full Depth Gravity and Capping Fill Gravity Trench and Bed Treatment and Disposal Systems shall be designed in accordance with the following criteria (see Exhibits K, L, M or N).
6.17.2 Landscape Position: Areas with good surface drainage which allow surface water to run off easily without ponding and which are not prone to flooding.
6.17.3 Slope: 0 ‑ 15%. Bed systems can not be sited on slopes > 2%, unless otherwise approved by the Department. All systems must be constructed with level bottoms and shall incorporate construction procedures prohibiting equipment from entering the excavation. Trench systems on slopes in excess of 15% shall be permitted only if the design is prepared by a licensed Class C Designer. Any such design shall incorporate construction procedures.
6.17.4 Depth to Limiting Zone: The limiting zone shall be a minimum of three (3) feet below the bottom of the trench Š 48 inches beneath the soil surface.
6.17.5 Percolation Rates:
6.17.5.1 6 ‑ 120 mpi: Gravity distribution systems may be allowed unless otherwise required by these Regulations. Construction of seepage trenches and beds in soils with percolation rates slower than 120 mpi shall not be permitted.
6.17.5.2 Faster than 6 mpi: A pressurized distribution system is required for seepage trenches or beds. The trench or bed may be placed between twelve (12) and twenty four (24) inches in order to maintain thirty six (36) inch separation distance between rapidly permeable material and the limiting zone.
6.17.6 All Low Pressure Pipe Treatment and Disposal Systems shall be designed in accordance with the following criteria (see Exhibits O & X).
6.17.7 Landscape Position: Areas with good surface drainage which allow surface water to run off easily without ponding and are not prone to flooding. Low pressure pipe treatment and disposal systems shall not be prescribed in coastal beach sands.
6.17.8 The depth to the bottom excavation shall be nine (9) inches to eighteen (18) inches. Trench width shall be no larger than twelve (12) inches, unless otherwise approved by the Department.
6.17.9 Depth to limiting zone: The limiting zone shall be a minimum of eighteen (18) inches below the bottom of the trench (i.e. a minimum of twenty seven (27) inches below existing grade for a nine (9) inch deep LPP trench system). Shallow disposal trenches (placed not less than nine (9) inches into the original soil profile) may be used with a capping fill to achieve the minimum separation distance specified above. The capping fill, if required, shall be placed in accordance with these Regulations (see Exhibit O). A capping fill cover is required for all LPP disposal systems with trench depths less than eighteen (18) inches.
6.17.10 Additional criteria:
6.17.10.1 Lateral lines of the LPP disposal system which are placed on lower landscape positions (i.e. concave slope) shall have an interceptor drain installed upslope of the uppermost lateral to intercept and divert subsurface waters away from the absorption facility as determined by a Class D Soil Scientist.
6.17.10.2 There shall be no soil disturbance to the proposed disposal area except the minimum required for installation. The soils may be rendered unsuitable should unnecessary soil disturbance occur. Particular care should be taken when clearing wooded lots so as not to remove the surface soil material.
6.17.10.3 LPP disposal systems shall be installed only with equipment approved by Department.
6.17.10.4 LPP disposal systems shall not be allowed where sand lining is required or where soils have been filled or disturbed.
6.17.11 All Elevated Sand Mound Treatment and Disposal Systems shall be designed in accordance with the following criteria (see Exhibit P).
6.17.12 Landscape Position: Areas with good surface drainage which allow surface water to run off easily without ponding and are not prone to flooding.
6.17.13 Slope:
6.17.13.1 0 – 6% for soils with percolation rates slower than 60 mpi.
6.17.13.2 0 – 12% for soils with percolation rates faster than 60 mpi.
6.17.14 Depth to Limiting Zone: > 20 inches to evidence of a limiting zone.
6.17.15 Percolation Rate: 0 ‑ 120 mpi: Construction on soils with slower percolation rates is not permitted. A pressurized distribution system is required in all cases.
6.17.16 All Pressure-Dosed Full Depth and Capping Fill Treatment and Disposal Systems shall be designed in accordance with the following criteria (see Exhibits Q & R).
6.17.17 Landscape Position: Areas with good surface drainage which allows surface water to run off easily without ponding and are not prone to flooding.
6.17.18 Slope: 0 – 15%. Bed systems can not be sited on slopes > 2%, unless otherwise approved by the Department. All designs must be constructed with level bottoms and shall incorporate construction procedures prohibiting equipment from entering the excavation. Slopes in excess of 15% shall be permitted only if the design is prepared by a licensed Class C designer. Any such design shall incorporate construction procedures.
6.17.19 Depth to Limiting Zone: > Forty eight (48) inches to evidence of a limiting zone.
6.17.20 Depth to Limiting Zone: Forty eight (48) inches or greater from original grade and three (3) feet below bottom of filter aggregate. (i.e. a minimum of five (5) feet below existing grade for two (2) foot deep trench and bed systems).
6.17.21 Percolation Rate: 0 - 120 mpi. Construction on soils with slower percolation rates is not permitted. A pressurized distribution system is required in all cases.
6.17.22 All Sand-lined Treatment and Disposal Systems shall be designed in accordance with the following criteria (see Exhibit S).
6.17.23 Landscape Position: Areas with good surface drainage which allow surface water to run off easily without ponding and are not prone to flooding.
6.17.24 Slope: 0 – 15%. Slopes in excess of 15% shall only be allowed if the design is prepared by a Class C Designer. Any such design shall incorporate construction procedures.
6.17.25 Depth to Limiting Zone: Forty eight (48) inches or greater from original grade and three (3) feet below bottom of filter aggregate. Sand lined systems shall not be used where there is less than one (l) foot of unsaturated soil between the limiting zone and the impermeable or slowly permeable soil zone. Sand lining will not be permitted into the water table, except in instances where it is necessary for replacement systems to function hydraulically.
6.17.26 Percolation Rate: 0 ‑ 120 mpi. A pressurized distribution system may be required. The percolation test shall be taken in the permeable soil below the impermeable or less permeable soil zone. The bottom of the percolation test hole shall extend a minimum of six (6) inches below the slowly permeable soil zone but in no case shall it be less than six (6) inches above the underlying limiting zone. If the percolation tests are to be conducted at a depth too deep to obtain accurate percolation rates, a percolation rate based on USDA soil textures shall be assigned (see Exhibit W). Otherwise, hydraulic conductivity tests may be substituted.
6.17.27 Additional Criteria:
6.17.27.1 Sand lined systems may be used where the site evaluation has shown that there is an impermeable or slowly permeable soil zone located over an acceptable soil. Use of this system requires removal of that zone within the disposal area and its replacement with a sandy fill as prescribed under §6.4.1. The system shall be constructed in accordance with specifications for sand-lined seepage trenches and beds (see Exhibit S). Installation may require a Class D Soil Scientist on site to monitor depth of sand lining.
6.18 Septic Tanks:
6.18.1 The standard wastewater treatment system used for on‑site wastewater treatment and disposal shall be the septic tank.
6.18.2 All septic tank treatment units shall be designed in accordance with the following requirements (see Exhibit G).
6.18.3 The location of septic tanks shall be in accordance with the minimum isolation distances set forth in these Regulations as prescribed in Exhibit C.
6.18.4 The minimum liquid working capacity of septic tanks shall be:
6.18.4.1 For flows £ 500 GPD the minimum liquid working capacity shall be one thousand (1,000) gallons
6.18.4.2 For flows > 500 GPD but £ 15,000 GPD shall have a working capacity of 1.5 times the expected flow rate with a minimum liquid working capacity of one thousand five hundred (1,500) gallons
6.18.4.3 For flows > 15,000 GPD shall be determined on a case by case basis at the sole discretion of the Department
6.18.5 If large flow surges are anticipated the septic tank shall be increased in size to accommodate the surges without causing sludge or scum to be discharged from the tank.
6.18.6 All tanks shall be watertight, non‑corrosive, durable and structurally sound. Materials of construction for tanks shall be one of the following:
6.18.6.1 Cast‑in‑place reinforced concrete
6.18.6.2 Pre-cast reinforced concrete
6.18.6.3 Or other suitable material approved as equal, by, and at the sole discretion of, the Department
6.18.7 All septic tanks shall be of multi‑compartment design with a minimum of two (2) compartments. The first compartment of a two (2) compartment tank shall contain two‑thirds (2/3) the liquid capacity of the total volume of the tank. Tanks shall be of rectangular design.
6.18.8 Pre-cast reinforced concrete tanks shall have a minimum wall thickness of two and one‑half (2 ½) inches.
6.18.9 Cast‑in‑place reinforced concrete tanks shall have a minimum wall thickness of four (4) inches.
6.18.10 All inlet and outlet connections shall be sanitary tees or baffles constructed of cast‑in‑place concrete or PVC. Inlet openings may have a minimum diameter equivalent to the diameter of the house sewer but in no instance shall the diameter be less than three (3) inches. The outlet invert shall be two (2) inches below the inlet invert. The inlet and outlet baffles or sanitary tees shall extend at least twelve (12) inches below the liquid level, but to a level no deeper than 40% of the liquid depth. Baffles or sanitary tees are not necessary for any portion of the tank if it is to be used as a pumping chamber.
6.18.11 All pipe cutouts for inlet and outlet connections shall be sealed with a watertight concrete (95%) & bentonite (5%) grout mix or standard rubber gaskets.
6.18.12 Connections between multi‑compartment tanks shall consist of either a four (4) inch diameter sanitary tee or two (2) or more openings equally spaced across the width of the tank. Such openings shall be six (6) inches wide. All compartment connections shall extend to a level no deeper than 40% of the liquid depth as measured from the liquid level.
6.18.13 All inlet, outlet and inter-compartment connections shall be located to provide a minimum air space of one (1) inch between the top of the connection and the underside of the tank cover.
6.18.14 Each tank compartment shall be equipped with an access opening and cover. The opening shall be located to provide access to each tank compartment as well as providing access to the inlet and outlet connections for routine inspections. Access openings shall be at least eighteen (18) inches square or in diameter.
6.18.15 Each septic tank shall be constructed with a watertight access riser for each compartment and shall extend above grade. The riser and lid shall be made of concrete, masonry or an equivalent durable material approved by the Department. If multiple concrete risers are needed then water tight gaskets or hydraulic cement must be placed between each riser.
6.18.16 All above grade access covers shall be water tight and secure from vandalism.
6.18.17 All septic tanks shall be equipped with any outlet effluent filter approved by the Department. The maintenance of these filters is the responsibility of the property owner and must remain in service for the life of the septic tank. This unit must be maintained in accordance with the manufacturer’s service instructions.
6.19 All installations of septic tank treatment units shall be in accordance with the following requirements:
6.19.1 Excavation: The excavation shall be large enough to allow safe, unencumbered working conditions but in no case shall the size of the excavation be less than two (2) feet beyond the perimeter of the tank. Excavations shall be kept dewatered from surface drainage until backfilling is complete.
6.19.2 Foundations: The tank shall be placed on firm, dry, granular, undisturbed soil that has been graded level. A gravel bedding shall be used on damp or fine grained soils. A gravel bed foundation shall consist of stone no larger than that which will pass through a 3/4 inch sieve and shall be placed level to a minimum thickness of six (6) inches in the excavation. The gravel bed shall extend one (l) foot beyond the perimeter of the tank.
6.19.3 All tanks shall be placed on a level grade and at a depth that provides adequate gravity flow from the source. Where adequate flow from the source is maintained through the use of pumping equipment, the impact of pumping rates and potential surge flows shall be evaluated so as to maintain the treatment efficiency of the septic tank unit.
6.19.4 Previously excavated material from the tank excavation may be used for backfill provided the excavation material is dry and free of stones larger than four (4) inches in diameter, construction debris, concrete, wood and other similar materials. To equalize external pressure against the septic tank, backfill material shall be placed and compacted, extending a minimum of two (2) feet beyond the perimeter of the tank.
6.19.5 Backfill materials shall be placed in uniform layers not more than eight (8) inches thick and compacted to no less than 85% Modified Proctor Density. Tamping shall be done in a manner that will not produce undue stress or strain on the tank. All backfill shall be free of excessive moisture.
6.19.6 Testing: All tanks constructed on‑site (i.e., cast‑in place, concrete block, etc.) shall be tested to ensure watertight conditions and to check alignment and operation of inlet, inter-compartment and outlet connections prior to backfill. When tested, tanks shall be filled to overflowing with water to observe operation of all connections and fittings. All visible leaks in the tank observed by the installer shall be repaired prior to backfilling.
6.20 Grease Traps:
6.20.1 Grease traps shall be utilized for commercial and industrial wastewater sources at the sole discretion of the Department to assure the effectiveness of on‑site wastewater treatment and disposal systems. Grease interceptors shall not be approved for new construction designs as replacement for the grease trap. Grease interceptors may be allowed for replacement systems when there are site limitations and low flow applications.
6.20.2 All grease traps shall be designed in accordance with the following requirements. The minimum size grease trap shall be one-thousand (1,000) gallons (see Exhibits E & F).
6.20.3 The location of grease traps shall be in accordance with the minimum isolation distances set forth in these Regulations as prescribed in Exhibit C.
6.20.4 The sizing of grease traps shall be based on wastewater flow data and grease retention capacity. The grease retention capacity in pounds shall be equal to at least twice the peak flow capacity in gallons per minute. The flow capacity can be determined from the individual flows from fixtures discharging into the grease trap. Exhibit E contains the minimum flow rate fixture capacities which shall be used for grease trap designs when actual calibrated metered flow data indicating peak daily flows over a three (3) year period are not available.
6.20.5 All grease traps shall have multi‑compartments.
6.20.6 All inlet and outlet connections shall be sanitary tees or baffles constructed of cast-in-place concrete or PVC. Inlet and outlet openings shall be a minimum of four (4) inches in diameter. The outlet invert shall be two (2) inches below the inlet invert. The inlet baffle or sanitary tee shall extend at least twenty four (24) inches below the liquid level. The bottom of the outlet baffle or sanitary tee shall be eight (8) inches above the tank bottom.
6.20.7 Connections between multi-compartment tanks shall consist of a four (4) inch diameter sanitary tee. The bottom of the sanitary tee shall be twelve (12) inches above the tank bottom.
6.20.8 The requirements of §§6.18.6, 6.18.8, 6.18.9, 6.18.11, 6.18.13, 6.18.14, 6.18.15 and 6.18.16 shall apply to all grease traps approved in accordance with these Regulations.
6.20.9 All installations of grease traps shall be in accordance with the requirements of §6.19 and testing shall be conducted in accordance with §6.19.6 of these Regulations.
6.20.10 Grease traps must have access at grade.
6.21 Dosing and Diversion Systems
6.21.1 Effluent from on‑site wastewater treatment and disposal systems shall be transmitted to the absorption facility by gravity or pressure distribution systems or lifted by a lift station (see Exhibit V) to overcome elevational differences between the septic tank and the absorption facility.
6.21.2 Gravity dosing and distribution systems may be used when the design wastewater flow requires less than two-thousand (2,500) ft2 of disposal area for seepage trenches or seepage beds and the percolation rate is equal to or slower than six (6) minutes per inch.
6.22 Gravity distribution systems shall conform to the following requirements:
6.22.1 All unperforated gravity transmission pipe up to the distribution box shall be Sch. 40 PVC or ANSI Class 22 thickness cast iron and shall be at least four (4) inches or greater in diameter unless lifted by a lift station to a surge tank or the distribution box in which case one and one-half (1 ½) inch or two (2) inch Sch. 40 PVC pipe would be permissible with a minimum of twenty (20) feet of four (4) inch diameter Sch. 40 PVC pipe prior to entering the distribution box.
6.22.2 All gravity transmission pipes shall be placed on a firm undisturbed or well compacted soil. All joints shall be watertight. A minimum grade of one-eigths (1/8 ) inch per foot shall be provided for gravity transmission piping. Clean backfill shall be placed around and over the pipe and hand tamped to provide compaction.
6.22.3 All gravity distribution laterals shall be thin walled or Sch. 40 PVC and shall be four (4) inches in diameter. Perforated PVC pipe shall have three-eigths (3/8 ) to three-quarters (3/4 ) inch diameter holes a maximum of thirty (30) inches on center. Coiled and corrugated piping shall not be used. A grade of less than two (2) inches per one hundred (100) feet shall be provided for all gravity distribution laterals.
6.22.4 The design and construction of the gravity distribution system shall provide uniform application of the effluent. All distribution laterals shall be of equal length unless approved by the Department. The effluent shall be equally divided between laterals of the gravity distribution system by means of a distribution box.
6.22.5 Stepped trenches shall be used on sloping ground.
6.22.6 All distribution boxes shall conform to the following requirements (see Exhibit H):
6.22.7 Location: Distribution boxes shall be used with all gravity systems. They shall be located in accordance with the minimum horizontal isolation distances set forth in Exhibit C. A minimum distance of three (3) feet shall separate the inlet face of the distribution box from the septic tank outlet.
6.22.8 Capacity: Distribution boxes shall be sized to accommodate the number of distribution laterals required for the distribution system.
6.22.9 An inlet baffle shall be installed in all distribution boxes. The baffle shall be perpendicular to the inlet pipe and situated six (6) inches from the end of the inlet. The baffle shall be constructed of the same material as the distribution box and shall be a twelve (12) inch square rising from the box floor, centered with the inlet connection, and permanently affixed. PVC tees may be incorporated as baffles when plastic distribution boxes are used.
6.22.10 The inverts of all outlets shall be of the same elevation and at least one (l) inch below the inlet invert.
6.22.11 Each inlet and outlet distribution lateral shall be connected separately to the distribution box. Unperforated distribution piping shall extend a minimum of five (5) feet from the distribution box.
6.22.12 The requirements of §§6.18.6, 6.18.8, 6.18.9, 6.18.11 and 6.18.13 shall apply to all distribution boxes approved in accordance with these Regulations.
6.22.13 Distribution boxes shall be accessible either by means of a removable cover or access manhole which shall be located twelve (12) inches below grade unless another distance is approved by the Department.
6.22.14 All installations of distribution boxes shall be in accordance with the requirements of §6.19.
6.22.15 All installed distribution boxes shall be tested to insure watertight conditions and leveled to insure an even distribution of flow to each lateral under operating conditions.
6.22.16 Pressure distribution systems shall be utilized with:
6.22.16.1 Trench or bed systems receiving flows requiring more than 2,500 ft2 of disposal area
6.22.16.2 All sand mounds
6.22.16.3 Certain sand‑lined systems
6.22.16.4 All absorption facilities located on soils where percolation rates are faster than six (6) minutes per inch
6.22.16.5 All low pressure pipe systems
6.22.17 Pressure distribution systems shall conform to the following requirements:
6.22.17.1 All unperforated pressure transmission pipes shall be Sch. 40 or SDR 26 PVC pipe unless approved by the Department. The pipe shall be sized to provide a minimum flow rate of two (2) feet per second in the pipe.
6.22.17.2 All pressure transmission pipes shall be placed below the frost line. All joints shall be watertight and all pipes shall be placed on a firm undisturbed or well compacted soil. Clean backfill shall be placed around and over the pipe and hand tamped to provide compaction. Frost line minimums for each county are as follows:
 
Sussex – 24 inches
Kent – 24 inches
New Castle – 30 inches
6.22.17.3 All pressure distribution laterals shall be Sch. 40 and SDR 26 PVC pipe with diameters as determined by a Class C Designer. Minimum hole diameters for perforated pressure distribution laterals shall be five-thirtyseconds ( 5/32 ) to one-half ( 1/2 ) inch maximum and spacing intervals as determined by a Class C Designer and be placed on center along the length of the pipe. Maximum hole spacing shall be determined by percolation rates as follows:
 
NOTE: Balanced trench loading rates (gpd/ft2) must be considered where slopes are encountered. This can be accomplished by varying the number of lateral perforations (and spacing) and perforation diameter.
6.22.17.4 All laterals shall be connected to manifolds with tees or sanitary tees constructed of PVC corresponding to the size of the connecting laterals.
6.22.17.5 Distribution of effluent from the pressure transmission pipe to the distribution laterals shall be by a central PVC manifold.
6.22.17.6 The dose volume shall be designed so that the estimated daily flow shall be discharged to the absorption facility in a minimum of equal three (3) doses. Dose volume shall be five (5) times the internal (liquid) capacity of the pressure transmission pipe, manifold, and laterals not flooded.
6.22.17.7 The size of the dosing pumps or siphons shall be selected to maintain a minimum pressure of one (1) psi (2.31 feet of head) at the end of each distribution line. Pump characteristics and head calculations that include maximum static lift, pipe friction and orifice head requirements shall be submitted with permit applications.
6.23 Dosing Chambers (see Exhibit I)
6.23.1 Location: Dosing chambers shall be located in compliance with the minimum isolation distances of these Regulations (see Exhibit C).
6.23.2 Size/capacity: If the design daily flow is £ 500 GPD, the dosing chamber shall have a minimum liquid capacity equal to the designed dose volume plus the design daily flow. If the design daily flow is > 500 GPD, the dosing chamber shall have minimum liquid capacity equal to two (2) times the designed dose volume.
6.23.3 The requirements of §§6.18.6, 6.18.8, 6.18.9, 6.18.13, 6.18.14 and 6.18.16 shall apply to all dosing chambers approved in accordance with these Regulations.
6.23.4 All inlet pipe connections shall be located above the high water level as predetermined by the pump or siphon installation.
6.23.5 All pipe cutouts shall be sealed with a watertight concrete (95%) & bentonite (5%) grout mix or standard rubber gaskets.
6.23.6 Dosing chambers shall be constructed with a ventilation port and a watertight access manhole. The ventilation port shall be extended at least six (6) inches above grade while the access manhole shall be extended to the finished grade, at a minimum, the Department recommends six (6) inches above grade. The vent shall be three (3) inches in diameter and the access manhole shall be sized for easy removal of pumps or siphons. In no case shall the manhole be less than twenty (20) inches square or in diameter. The vent shall be turned down and shall be fitted with insect and rodent proof, corrosion resistant screen.
6.23.7 Pumps and siphons which are suitable for handling septic tank effluent shall be used to meet dosing requirements and shall be installed in accordance with the manufacturer's recommendations.
6.23.8 Dosing chambers using pumps shall have an installed pump for which a replacement is readily available in the event of failure.
6.23.9 Pumps and siphons shall be sized to discharge a flow rate equal to the combined flows from all discharge holes in the laterals when operating at designed level or head.
6.23.10 Pumps and valves shall be equipped with suitable connections so that they may be removed for inspection or repair without entering the dosing chamber. A slide rail system or disconnect coupling accessible from outside the dosing chamber shall be utilized to allow removal and access to the pump and pump check valve for repairs and maintenance. A corrosion‑proof lifting device shall be attached to the pumps and tied off at the access manhole.
6.23.11 Check valves shall be required on all pressure distribution systems.
6.23.12 An audible and visual high level warning device shall be installed for all siphons and pumps and shall be installed on a separate AC circuit from the pump.
6.23.13 All pump electrical connections and alarm controls shall be corrosion resistant and waterproof.
6.23.14 Elevations for pump controls and high water level sensor elevations shall be provided in the design.
6.23.15 Testing: All dosing chambers constructed on‑site (i.e., cast‑in‑place, concrete block, etc.) shall be field tested to ensure watertight conditions. Pumps, siphons, alarm controls and related appurtenances shall also be field tested to ensure accuracy and proper operation in accordance with the manufacturer's recommendations. A minimum schedule for periodic testing and calibration of the dosing chambers, pumps, siphons, alarm controls and related appurtenances shall be established and incorporated into the permit. All installed pumps and siphons shall be accompanied by instruction manuals that include operation and maintenance procedures and pump characteristics.
6.24 Diversion Boxes and Diversion Valves.
6.24.1 Location: Diversion boxes or diversion valves for dual systems shall be located according to the requirements set forth in Exhibit C.
6.24.2 Capacity: Diversion boxes and valves shall be sized to accommodate the piping connected to them.
6.24.3 Diversion Valves: All pressure dosed dual systems shall use diversion valves.
6.24.4 All installation of diversion boxes shall be in accordance with the requirements of §6.19.
6.24.5 Diversion boxes shall be pre-cast concrete or other approved products. Diversion valve systems shall be commercially available and diversion or gate valves shall be constructed of durable cast iron or plastic.
6.25 Diversion Box and Diversion Valve Specifications (see Exhibit J):
6.25.1 All diversion boxes and diversion valves shall be installed level with connecting piping to minimize stress.
6.25.2 Cast iron valves shall be free of dirt and rust. Plastic valves shall be clean and dry before installation.
6.25.3 Diversion boxes may be standard distribution boxes with selective flow diversion devices.
6.25.4 All inlet and outlet cutout connections shall be sealed watertight with grout or approved rubber gaskets.
6.25.5 Appurtenances: All buried valves shall be furnished with a suitable box constructed of durable material extended to grade with a tight fitting access cap.
6.25.6 Testing: Installed valves and gates shall be tested in the field prior to back fill. Pre-cast boxes shall be tested for watertight conditions.
6.26 Building Sewers
6.26.1 The minimum requirements contained in this Section shall apply to all conduits, pipes or sewers which transmit wastewater flows from building or house drains to a septic tank (or other treatment device) and from the septic tank (or other treatment device) to the distribution box or dosing tank. Collection systems servicing three (3) or more units (i.e., community systems) shall be in conformance with National Standards.
6.26.2 Building sewers shall comply with the following requirements:
6.26.2.1 Location: A minimum horizontal separation of ten (10) feet shall be provided between a house or building sewer and any water line. Suction lines from wells shall not cross under house or building sewers.
6.26.2.2 Size: Building sewers shall be sized to serve the expected flow from the connected fixtures. All building gravity sewer plumbing shall be at least as large as the internal building plumbing but in no case less than three (3) inches in diameter. Pressure building sewers transmitting wastewater to a septic tank (or other device) shall be a minimum of two (2) inches in diameter.
6.26.2.3 Foundation: All building sewers shall be laid on a firm compacted bed through its entire length. Building sewers placed in wet soil shall have a four (4) inch bedding of 3/4 inch to 1‑1/2 inch aggregate.
6.26.2.4 Materials: Building sewers shall be constructed of ANSI Class 22 thickness cast iron, Sch. 40 or Sch. 80 PVC, reinforced concrete, or Sch. 40 or Sch. 80 ABS pipe. Cast iron pipe or PVC pipe encased in six (6) inches of concrete shall be used for building sewers located < 3 feet below driveways, parking area, or other areas subject to vehicular traffic or similar loading. The cast iron pipe or encasement shall extend a minimum of two (2) feet beyond the edge of driveways, parking areas, or other areas subject to vehicular traffic or similar loading and shall be adequately bedded.
6.26.2.5 Joints: All pipe joints shall be watertight and protected against external and internal loads.
6.26.2.6 Grade: A building sewer shall be installed in a straight line to the maximum extent practicable with a uniform continuous grade not less than l/8 inch/foot, unless it can be demonstrated to the satisfaction of the Department that an alternative design can maintain adequate flow from the source and is approveable under the applicable local building code.
6.26.2.7 Cleanouts: Building sewer cleanouts shall be installed at minimum intervals of fifty (50) feet for three (3) inch diameter pipe and one hundred (100) feet for four (4) inch and larger diameter pipe. Cleanouts shall be provided at all changes in direction greater than 45o. Wherever possible, bends should be limited to 45o. Every house or building sewer shall have at least one (1) cleanout fitting to provide access to the plumbing. Cleanouts may be placed at greater distances provided National Standards are used to design the total collection system.
6.27 Water Conservation Devices.
6.27.1 Twenty five (25) percent reductions in design flow are allowed for water conservation. The absorption facility shall be enlarged to the original required size if the conservation devices are removed, become inoperative, or the system malfunctions.
6.27.2 Water saving plumbing devices are encouraged to lengthen the life of the absorption facility. However, only permanent water saving plumbing devices such as low flush toilets shall be considered in reducing the size of the absorption facility. Devices such as inserts in showers are considered temporary.
 
7.0 Siting Density and Hydrogeological Requirements
7.1 The minimum isolation distances and siting densities set forth in these Regulations shall be maintained when designing, locating, constructing, repairing, replacing and installing holding tanks, commercial and individual on-site and community wastewater treatment and disposal systems.
7.2 The following maximum siting densities shall be maintained:
7.2.1 For residential dwellings, the maximum siting density shall be one (1) dwelling unit per one‑half (1/2) acre.
7.2.1.1 For single family residences, only the area within the property lines of the lot shall be considered.
7.2.1.2 For multiple family dwellings or where more than one (1) dwelling is to be served by an on‑site wastewater treatment and disposal system, the maximum siting density shall be based on the net pervious area (i.e., unpaved, without structures) available for groundwater recharge after total project completion. The following criteria shall be utilized in determining the maximum siting densities:
7.2.1.2.1 For projects utilizing only a septic tank for treatment prior to discharge to the absorption facility, the maximum siting density shall be one (1) dwelling unit per one‑half (1/2) acre of pervious area.
7.2.1.2.2 For projects utilizing advanced treatment systems, in conformance with standard engineering practice and providing higher degrees of nitrogen removal, the maximum siting density shall be determined based on the degree of nitrogen removal prior to discharge to the absorption facility. The degree of nitrogen removal required will be determined in accordance with Exhibit U. The degree of nitrogen removal may be adjusted in accordance with a schedule for total project completion submitted by the applicant and approved by the Department. The owner of a treatment system which provides a higher degree of nitrogen removal shall post a performance bond or certified letter of credit in an amount equal to the total cost of the treatment system for the project. The performance bond shall be held by the Department until, such time as the treatment system demonstrates an acceptable level of compliance with the terms and conditions of a permit for a minimum period of one (1) year. Upon demonstration of a satisfactory level of compliance, the performance bond or certified letter of credit will be returned to the owner.
7.2.2 For commercial facilities the maximum siting density shall be established by dividing the projected design flow by five hundred (500) gallons per day per one‑half (1/2) acre and shall be based on the net pervious area (i.e., unpaved, without structures) available for groundwater recharge after total project completion. Campgrounds intended for overnight or transient use are evaluated as commercial facilities as opposed to manufactured home communities, which are evaluated as single family residential facilities.
7.2.3 In establishing maximum siting densities the Department may consider impervious areas where it can be demonstrated that through the establishment of an acceptable stormwater management plan, all runoff will be recharged to the groundwater of the State within the boundaries of the project site. Stormwater management plans shall be based upon a ten (10) year - one (1) hour storm event as a minimum and provide recharge of the runoff within seventy two (72) hours of the storm event.
7.3 If the deed or instrument, under which an owner acquired title to a lot or parcel, was of record prior to April 8, l984 and if such lot or parcel does not conform to the requirements of §7.2.1, then the Department may approve a feasibility study and/or issue a construction permit for an on‑site wastewater treatment and disposal system. This system is to serve a single family dwelling or for multiple systems to serve dwellings to be situated within an area which has been given final site plan approval prior to April 8, l984 for single or multi‑family dwellings provided that:
7.3.1 The number of dwelling units per net pervious area (i.e. unpaved, without structures) does not increase from those approved prior to April 8, l984 by the local governmental unit having jurisdiction; and
7.3.2 At the time the permit is issued or feasibility study is approved, the lot or parcel complies with the requirements of §3.0 through §6.0 of these Regulations.
When it may be necessary to increase the net pervious area or reduce the number of dwelling units within a lot or parcel and thus create a new date of recordation or final site plan approval, the Department shall utilize the previous date of recordation or approval in determining conformance with these Regulations. The owner shall provide, prior to any action by the Department, all documentation determined by the Department to be necessary in establishing conformance with this section.
7.4 For lots created by plats or deeds recorded after April 8, l984 and/or when the on‑site wastewater treatment and disposal system will serve a commercial facility, the Department may approve a feasibility study and/or issue a construction permit for a new on‑site wastewater treatment and disposal system if it is determined that all Regulations of the Department can be met.
7.5 Isolation distances and siting densities may be modified by the Department based upon a site specific Groundwater Impact Assessment (GIA) provided that in the sole discretion of the Department such modification will allow for the protection of environmental resources and public health, safety and welfare. A site specific GIA may not be required when the proposed treatment prior to disposal will discharge no greater than five (5) milligrams per liter of total nitrogen as an average of all samples collected within a calendar year and not exceed ten (10) milligrams per liter of total nitrogen during any one month while providing adequate disinfection at all times.
7.6 The Department may require an applicant, owner or operator to perform a site specific Groundwater Impact Assessment (GIA) when a proposed or existing large system will likely or is likely causing unacceptable environmental impacts and/or risk to public health. The GIA should be performed by a Delaware Registered Professional Geologist and shall be based upon site specific investigations and testing. If information required in the GIA was previously submitted in a PGIA for the site, the required information need not be resubmitted. The applicant may reference the PGIA and state that the information was submitted in the report. The Department will provide general and site specific guidelines for preparing the GIA.
7.7 The requirements of this Section are subject to waiver by the Department for a specific area upon petition by an appropriate governmental unit. Such petition shall provide reasonable evidence that development using individual on‑site wastewater treatment and disposal systems will not cause unacceptable degradation of groundwater quality or surface water quality or it shall provide equally adequate evidence that degradation of groundwater or surface water quality will not occur as a result of such waiver.
 
8.0 Maintenance
8.1 The owner shall be responsible for maintaining and operating on‑site wastewater treatment and disposal systems. Upon transfer of ownership, the new owner shall be responsible for proper operation and maintenance of the system and will be subject to all penalties for any violation of these Regulations.
8.2 Each on‑site wastewater treatment and disposal system shall be pumped by a licensed class F Liquid Waste Hauler once every three (3) years and alternative treatment systems shall be pumped according to manufacturer recommendations unless determined that the tank is less than one-third (1/3) full of solids. The schedule shall be prescribed in accordance with current Department guidelines based on the size of the treatment unit and anticipated number of residents. The owner of the on‑site wastewater treatment and disposal system shall maintain a record indicating the system has been pumped and provide such documentation to the Department upon request.
8.3 Organic chemical septic tank cleaning agents shall not be used in individual or community on‑site wastewater treatment and disposal systems.
8.4 Grease traps shall be cleaned when seventy five (75) percent of the grease retention capacity has been reached.
8.5 The sites of the initial and replacement absorption facilities shall not be covered by asphalt or concrete or subject to vehicular traffic or other activity which would adversely affect the soils. These sites shall be maintained so that they are free from encroachments by accessory buildings and additions to the main building.
8.6 The Department may impose specific operation and maintenance requirements for on‑site wastewater treatment and disposal systems to assure continuity of performance.
8.7 For large systems which serve communities that experience a significant variation in flow on an annual basis, the Department may prescribe specific criteria in the permit for taking certain treatment units out of service during periods of low flow. The criteria will establish procedures for winterization and restart and the minimum levels of treatment which must be provided at all times and in no event shall it be less than the level of treatment provided by a conventional on-site wastewater treatment and disposal system.
8.8 The Department shall impose, in any permit for large or community systems, standards for evaluating treatment system performance and compliance with these Regulations. The standards may be in the form of limitations on flow and pollutant concentrations and/or mass loadings. The standards shall reflect the utilization of best management and operational practices.
8.9 Unless otherwise required by a permit, all community and large systems shall be inspected annually by the Department or its designee.
8.10 Alternative systems shall be inspected by the Department or its designee once every three (3) years and a fee may be required.
8.11 The Department recommends alternative systems be inspected annually, at a minimum.
 
9.0 Preliminary Wastewater Treatment & Disposal Review
9.1 It is the policy of the Department to facilitate compliance with these Regulations through review of proposed development projects as early as possible in the development process to avoid unnecessary conflicts and expense. Any development project, which may or may not constitute a major subdivision, can submit a feasibility study to satisfy other local government approval processes. Any project that proposes to use individual on‑site and/or community/large wastewater treatment and disposal systems must submit a letter of intent prior to initiating any preliminary soil investigations.
9.1.1 The letter of intent must contain the following details:
9.1.1.1 The name of the Developer and landowner
9.1.1.2 The size of parcel and tax parcel number(s)
9.1.1.3 Projected start date of site/soil investigative work
9.1.2 If the proposed number of lots is fifty (50) and fifty (50%) percent of the on-site soils have limiting zones < forty eight (48) inches or the number of lots is one hundred (100) or a large on-site wastewater treatment and disposal system (LOWTDS) is proposed, proceed to the requirements of §5.12000, if not, proceed to §9.01020. If a preliminary review is desired prior to the submission of a SIR, the Soil Scientist may submit a feasibility study in accordance with §9.01017.
9.1.3 A feasibility study for a LOWTDS shall contain the following information:
9.1.3.1 Site plan drawn to scale not to exceed one (1) inch equals two hundred (200) feet
9.1.3.2 Illustrate topography on two (2) foot contour intervals unless the Department approves the use of an alternate scale due to extreme variations in the elevation on the site
9.1.3.3 Conduct a soil suitability evaluation of the project site following the procedures prescribed in §5.1. The area of investigation should be concentrated within the proposed LOWTDS. The soil scientist must demonstrate the area proposed for the LOWTDS represents the best soils on the project site. The extent and nature of the soil evaluation shall be determined by the Class D Soil Scientist.
9.1.3.4 Based on preliminary design criteria established by the Class D Soil Scientist, as a result of the soils evaluation, a preliminary engineering study prepared by a Class C Designer must be included which demonstrates the suitability of the evaluated area for the proposed number of lots. The engineering study must include, at a minimum, the proposed method of disposal, proposed treatment levels, and proposed design flow rates, along with preliminary calculations/layout to demonstrate there is sufficient area for both the initial and replacement system.
9.1.3.5 The Department may ask for any additional information deemed necessary on a case-by-case basis to make a statement of feasibility.
9.1.4 A feasibility study shall be filed with the Department setting forth the proposed manner of compliance with these Regulations. The feasibility study shall contain the following information:
9.1.4.1 Site plan must be drawn to scale not to exceed one (1) inch equals two hundred (200) feet
9.1.4.2 Illustrate topography by two (2) foot contour intervals unless the Department approves the use of an alternate scale due to extreme variations in elevation on the site
9.1.4.3 Illustrate the approximate location of all wells, watercourses, roads and on-site wastewater treatment and disposal systems within one hundred fifty (150) feet of the perimeter of the property
9.1.4.4 Conduct a soil suitability evaluation of the project site following procedures prescribed in §5.1. The extent and nature of the soil evaluation shall be determined by a Class D Soil Scientist. The Soil Scientist shall coordinate the planning of the soils evaluation with the Department prior to initiating work
9.1.4.5 Indicate the type of limiting zone, its depth, and list the results of the site and soils analysis on the appropriate forms
9.1.4.6 Each soil interpretative unit identified for potential on-site wastewater treatment and disposal shall have at least one (1) percolation test conducted within it to establish representative percolation rates for each interpretative unit
9.1.4.7 Lot numbers and approximate lot areas shall be provided
9.1.4.8 A general site location map shall be included on the preliminary plan for reference identification of the area
9.1.4.9 Proposed stormwater management areas
9.1.4.10 Location of any jurisdictional wetlands, if delineated
9.1.4.11 Any other information required by the Department on a case by case basis.
9.2 The Department shall conduct a general review of the preliminary plan and give the owner/developer a statement of preliminary subdivision feasibility which shall contain a statement of on-site wastewater treatment and disposal feasibility. This Section shall not be construed to relieve the applicant of the responsibility of obtaining individual site evaluations and permits from the Department for each lot prior to commencement of construction of any on‑site wastewater treatment and disposal system.
 
10.0 Variances
10.1 Rural Area Variances
10.1.1 Variances for any provision of these Regulations may be granted by the Secretary in certain rural zones provided that:
10.1.1.1 The owner executes and records in the appropriate County Office of the Recorder of Deeds an affidavit, on a form approved by the Department, which notifies prospective purchasers that the property is subject to a Rural Area Variance; and
10.1.1.2 The parcel size is not less than ten (10) acres; and
10.1.1.3 The permit is for an on‑site wastewater treatment and disposal system designed to serve a single family dwelling; and
10.1.1.4 The on‑site wastewater treatment and disposal system will function in a satisfactory manner so as not to create a public health hazard; and
10.1.1.5 Applications must be completed per §10.2.3 to obtain final approval for the Rural Area Variance.
10.2 Formal Variances
10.2.1 Variances from any provisions contained in these Regulations may be granted after a public notice and hearing, if any. Notice shall be provided to all contiguous property owners. A public hearing will be held if a meritorious request is received within a reasonable time as stated in the advertisement. A public hearing request shall be deemed meritorious if it exhibits a familiarity with the application and a reasoned statement of the variance's probable impact.
10.2.2 No variance may be granted unless the hearing officer finds, or in the case of an appeal to the Environmental Appeals Board, it is found that;
10.2.2.1 The requirements of 7 Del.C. Ch. 60, §6011 have been satisfied; and
10.2.2.2 Strict compliance with the provision of these Regulations is inappropriate for cause; or
10.2.2.3 Special physical conditions render strict compliance unreasonable, burdensome, or impractical.
10.2.3 Applications for Variances
10.2.3.1 A separate application shall be made to the Department for each site considered for a variance.
10.2.3.2 Each Rural Area Variance application shall include:
10.2.3.2.1 A site evaluation report conducted by a Class D Soil Scientist, unless waived by the Department, to include the requirements of §10.1; and
10.2.3.2.2 Proof the parcel is a minimum of ten (10) acres (survey or statement from zoning office); and
10.2.3.2.3 Location of any jurisdictional wetlands, if delineated; and
10.2.3.2.4 A proposed disposal location which is a minimum of one hundred (100) feet from all property boundaries (when soil conditions allow); and
10.2.3.2.5 The location of all wells within one thousand (1,000) feet of the proposed absorption facility; and
10.2.3.2.6 The property owner(s) shall provide a list of all property owners names and addresses within one thousand (1,000) feet of parcels property lines; and
10.2.3.2.7 A percolation test conducted by a Class A Percolation Tester or an assigned percolation rate by the Class D Soil Scientist based upon USDA soil textures (see Exhibit W); and
10.2.3.2.8 Submit soils report with appropriate site evaluation fee, if fee not paid already. Upon reviewing the soils report, the Department will determine the system type, design specifications and return this information to the owner, or designated agent.
10.2.3.3 Upon completion of §10.2.3.2, the following criteria will be required:
10.2.3.3.1 A completed permit application prepared by a licensed designer; and
10.2.3.3.2 An affidavit of a Rural Area Variance (as part of the permit application); and
10.2.3.3.3 Appropriate fee’s for the permit application and Rural Area Variance, if not already paid; and
10.2.3.3.4 The Department shall advertise the application for a Rural Area Variance in a local newspaper to include direct notification of adjacent property owners. The Department will not hold a public hearing unless a meritorious request is made to the Department.
10.3 Hardship Variances
10.3.1 The Secretary may grant variances from any provision of these Regulations in cases of extreme and unusual hardship.
10.3.2 The Department may consider the following factors in reviewing an application for a variance based on hardship:
10.3.2.1 Advanced age or bad health of the applicant;
10.3.2.2 Need of applicant to care for aged, incapacitated, or disabled relatives;
10.3.2.3 Relative insignificance of the environmental impact of granting a variance
10.3.3 Hardship variances granted by the Secretary may contain conditions such as:
10.3.3.1 Permits for the life of the applicant;
10.3.3.2 Limiting the number of permanent residents using the system;
10.3.3.3 Use of conventional on-site wastewater treatment and disposal systems for specified periods of time;
10.3.3.4 Any other conditions which the Secretary finds in his/her sole discretion to be appropriate.
10.3.4 At the time of the application, the applicant must designate on the application that it is for a hardship variance.
10.3.5 Documentation of hardship must be provided before the application is referred to the Department for action.
10.3.6 Department personnel shall strive to aid and accommodate the needs of applicants for variances due to hardship.
10.4 Variance Hearings
10.4.1 The hearing officer shall hold a public hearing in conformance with 7 Del.C. Ch. 60, §6006.
10.4.2 The hearing shall be held in the county where the property is located.
10.5 Variance Appeals
10.5.1 Decisions of the Secretary to grant or deny a variance may be appealed to the Environmental Appeals Board.
8 DE Reg. 1491 (04/01/05)
 
Exhibits A through Z
 
A. Existing On-Site Wastewater System Field Inspection Report Example & Guidelines
B. Textural Triangle for Soil Classification
C. Minimum Isolation Distances
D. Wastewater Design Flow Rates
E. Grease Trap Design Capacities
F. Typical Grease Trap
G. Typical Two Compartment Septic Tank
H. Typical Distribution Box
I. Typical Pump Dosing Chamber
J. Diversion Equipment for Dual Fields
K. Typical Aggregate Trench/Bed Design – Full Depth Gravity
L. Typical Aggregate Free Trench/Bed Design – Full Depth Gravity
M. Typical Aggregate Trench/Bed Design – Capping Fill Gravity
N. Typical Aggregate Free Trench/Bed Design – Capping Fill Gravity
O. Typical Low Pressure Pipe Design
P. Typical Elevated Sand Mound Design
Q. Typical Pressure-Dosed Trench/Bed Design – Full Depth
R. Typical Pressure-Dosed Trench/Bed Design – Capping Fill
S. Typical Sand-Lined Trench/Bed Design
T. System Information Quick Reference Guide
U. Total Nitrogen Concentrations for Community Systems
V. Septic Tank Lift Station
W. Percolation Rates Based Upon USDA Soil Textures
X. Low Pressure Pipe Design Percolation Rates & Maximum Hole Spacing Distances
Y. Observation Well Construction Diagram
Z. System Abandonment Report
 
FOREWORD
 
The Delaware Department of Natural Resources and Environmental Control (the Department) finds that a substantial portion of the State’s population lives where centralized water supplies or wastewater treatment services are limited. It is the intent of the Department to aid and assist the public in the installation of on-site wastewater treatment and disposal systems, where possible, by utilizing the best information, techniques and soil evaluations for the most suitable system that site and soil conditions permit.
Statewide regulations governing the installation and operation of wastewater treatment and disposal systems have existed since 1968. Inappropriate installations and poor operation and maintenance practices have resulted in treatment and disposal system malfunctions. Inadequately renovated wastewater has contaminated the State’s groundwater and is presenting a threat to the public health, safety, and welfare. Corrective measures require the replacement of water supply and wastewater systems, sometimes at a very high cost, which is sometimes borne by the general public. As such the Department’s regulations governing the site evaluation, siting density, installation, operation and maintenance of on-site wastewater treatment and disposal systems have been identified as requiring revisions.
Through a process that included considerable staff research, consultant studies, the development of background “working papers”, interaction with public/private sector on-site wastewater industry professionals, public meetings and presentations, public workshops, a public hearing and a hearing officer’s report along with draft versions of this Regulation were prepared, reviewed and revised. This final version is the result of those various activities, and incorporates, as best as possible, all valid concerns into its provisions.
They are based on the best information available and include the establishment of a process for updating this Regulation as information changes. They include what are considered to be the best engineered design standards for on-site systems, as determined by research and practical experience. These Regulations seek to require the use of on-site wastewater treatment and disposal systems that will function according to their performance criteria without causing the State’s groundwater resources to violate U. S. Environmental Protection Agency Drinking Water Standards on an average annual basis.
This document also provides for the planning, design, and operation of slow rate land treatment systems for wastewaters in Delaware. The term slow rate land treatment as used in these regulations refers to the advanced treatment of wastewater by irrigation onto land to support vegetative growth. These systems are designed and operated so there is no direct discharge to surface waters. The irrigated wastewater evaporates and transpires to the atmosphere or enters the groundwater through percolation. Organic constituents in the wastewater are stored in the soil or stabilized by soil bacteria. Properly designed and operated wastewater irrigation systems produce a percolate water of high quality and thus protect ground and surface water resources.
The proper siting of wastewater treatment and disposal systems is addressed by the establishment of various soil criteria and hydrogeologic criteria which lead to the selection of the most suitable on-site wastewater treatment and disposal system for local conditions. System selection and sizing are determined using the results of the site specific soil evaluations, infiltrometer tests and/or hydrogeologic suitability investigations. Soil evaluation and system selection, design, installation, operation and maintenance are required to be performed by individuals licensed under these Regulations.
Although it has not been possible to include every method of on-site treatment and disposal, the Department’s policy is to encourage development of new systems, processes and techniques which may benefit significant numbers of people within Delaware. It is expected that these Regulations will be reviewed and revised periodically and that standards for future methods of wastewater treatment and disposal will be evaluated as more experience and research data become available. The Regulations contain provisions that enable that process to occur.
 
1.0 Authority and Scope
1.1 These Regulations are adopted by the Secretary of the Department of Natural Resources and Environmental Control under and pursuant to the authority set forth in 7 Del.C. Ch. 60.
1.2 These Regulations shall apply to all aspects of:
1.2.1 The planning, design, construction, operation, maintenance, rehabilitation, replacement, inspection and modification of on‑site wastewater treatment and disposal systems within the boundaries of the State of Delaware; and
1.2.2 The planning, design, construction and operation and maintenance of on‑site wastewater holding tanks within the boundaries of the State of Delaware; and
1.2.3 The licensing of percolation testers, on‑site wastewater treatment and disposal system designers, soil scientists, on‑site wastewater treatment and disposal system contractors, system inspectors and liquid waste haulers within the boundaries of the State of Delaware.
1.3 These Regulations shall supersede and replace the Regulations Governing the Design, Installation, and Operation of On-Site Wastewater Treatment and Disposal Systems and the Guidance and Regulations Governing the Land Treatment of Wastes, Part II. With respect to the other provisions of the Regulations Governing the Control of Water Pollution these Regulations shall supersede such Regulations only to the extent of any inconsistency. These Regulations shall apply throughout the State of Delaware.
1.4 The Department has the authority to establish and collect fees for the defraying of expenses incurred by the Department for facilities and services needed to provide for the administration of its programs. The authority is contained within 68 Del. Laws C. 86 §14, which also contains the schedule of fees.
 
2.0 Definitions
2.1 The following words and terms, when used in this Regulation, shall have the following meaning unless the text clearly indicates otherwise:
Absorption facility” means a system of open jointed or perforated piping, alternative distribution units or other seepage systems for receiving the flow from septic tanks or other treatment facilities and designed to distribute effluent for oxidation and absorption by the soil within the zone of aeration.
Advanced treatment unit” means any process designed to produce an effluent of higher quality than normally achieved by secondary treatment processes or containing unit operations not normally found in secondary treatment which also incorporates nutrient removal processes that achieve PSN3 requirements.
Affidavit of Ownership” means a formal sworn statement of ownership, signed by the declarant (who is called the affiant or deponent) and witnessed (as to the veracity of the affiant's signature) by a taker of oaths, such as a notary public.
Aggregate-free chambers” means a buried structure used to create an enclosed unobstructed soil bottom absorption area and side-wall absorption area for infiltration and treatment of wastewater which can be used to replace the filter aggregate and distribution pipe in an absorption facility.
"Agricultural land" means land cultivated for the production of crops or used for raising livestock.
"Agricultural wastes" means wastes normally associated with the production and processing of food and fiber on farms, feedlots, ranches, ranges, and forests which may include animal manure, crop residues, and dead animals; also agricultural chemicals, fertilizers and pesticides which may find their way into surface and subsurface water.
Agricultural well” means a non-potable well used for watering livestock, aquaculture, or watering household yards and gardens, or for other purposes related to farming but not for irrigating lands or crops.
Alternating system” means two or more disposal fields, equal in size with dosing provided alternatively to each field.
Applicant” means the owner or legally authorized agent of the owner as evidenced by sufficient written documentation who has submitted an application to the Department for review and approval.
Authorization to use existing system permit” means a written document issued by the Department which states that an on‑site wastewater treatment and disposal system appears adequate to serve the purpose for which a particular application is made and that the system may be placed into operation.
Aquifer” means a part of a formation, a formation, or a group of formations that contains sufficient saturated permeable material to yield economically useful quantities of water to wells and springs.
Authorized agent” means a person given the authority to act on the owner’s behalf for filing an application with the Department either to sign on behalf of the owner or to act as the contact person to receive all correspondence.
Backfill” means a soil which is clean and free of foreign debris, placed over the disposal area and fill extensions.
Biosolids” means the nutrient-rich organic materials resulting from the treatment of sewage sludge: the solid, semisolid or liquid untreated residue generated during the treatment of domestic sewage in a treatment facility.
Blackwater” means waste carried off by toilets, urinals, and kitchen drains.
BOD5” means biochemical oxygen demand which is the amount of oxygen required by bacteria to stabilize decomposable organic matter under aerobic conditions.
Building drain” means the piping coming from inside a building that extends five (5) feet beyond the exterior walls of the building and conveys wastewater to the building sewer.
Building sewer” means piping which carries wastewater from a building drain to the first component of the treatment and disposal system.
Capping fill gravity” means a gravity fed on-site wastewater treatment and disposal system which maintains a minimum 36 inches of separation distance above the limiting zone where the trench or bed is installed between 12 and 23 inches into the natural soil below a soil cap of a specified depth and texture.
Certified service provider” means any of the following responsible parties:
An individual representative of a manufacturer/supplier who holds a DNREC Class E System Contractor or Class H System Inspector license; or,
Cesspool” means a covered pit, with a porous lining, into which wastewater is discharged and allowed to seep or leach into the surrounding soils with or without an absorption facility. Note: Cesspools cannot be certified for real estate transfers.
Class H inspection” means the inspection of an existing OWTDS by an individual licensed as Class H system inspector by the Department to inspect, investigate and collect data detailing the current operating condition and type of system on Department authorized forms as observed on a specific date and time.
Commercial facility” means any structure or building, or any portion therefore, other than a residential dwelling.
Community system” means an on-site wastewater treatment and disposal system which serves more than three (3) lots, parcels, condominium units or units of a planned unit development.
Completed application” means the application form is properly completed in full, is signed by the applicant, is accompanied by all required documents, exhibits, detailed plans and specifications, and required fee.
Confined aquifer” means a saturated layer of permeable geologic material bounded above and below by confining layers, and in which water pressures are greater than atmospheric.
Confining layer” means a stratum of impermeable or distinctly less permeable material stratigraphically adjacent to one or more aquifers.
Construction permit” means a permit issued by the Department for the construction, repair or replacement of an on‑site wastewater treatment and disposal system.
Construction report” means a Department approved form prepared by the contractor and submitted to the Department within 10 calendar days after the absorption facility has been completely installed.
Conventional on-site wastewater treatment and disposal systems (OWTDS)” means those small systems which are referred to as; gravity, low pressure pipe, pressure-dosed, Wisconsin at-grade and elevated sand mound.
Crops” means a plant growing where it is desired for man and his welfare as opposed to weeds which interfere with the activities of man, his welfare and are growing where it is undesirable.
"Crops for direct human consumption" means crops that are consumed by humans without processing to minimize pathogens before distribution to the consumer.
Declaration of Covenants & Restrictions” means a legal obligation imposed by the seller upon the buyer of real estate.
Department” means the Department of Natural Resources and Environmental Control of the State of Delaware (DNREC).
Developer” means a person, persons, partnership, firm, corporation or cooperative enterprise undertaking and/or participating in the development of a subdivision, manufactured home community, or multi‑unit housing project.
Director” means the Director of the Division of Water for the State of Delaware or his/her authorized representative.
"Disposal" means the discharge, deposit, injection, dumping, spilling, leaking, or placing of wastewater, other liquid waste, or any constituent of it on or in the land, the air or any waters, including groundwater, and includes any method of utilization that involves reuse of the nutrients at greater than agronomic rates.
Disposal area” means the entire area used for the absorption facility.
Distributed wastewater” means treated and filtered wastewater provided for disposal, reuse or any other purpose consistent with the intent of these Regulations.
Distribution box” means a box for distributing wastewater equally to separate distribution laterals of the absorption facility by means of gravity.
Distribution system” means piping or other devices used in the distribution of wastewater within the absorption facility (also referred to as distribution laterals).
Domestic waste” means solid waste, composed of garbage and rubbish, which normally originates in a private home or apartment house and may contain toxic or hazardous waste.
Dosing” means the pumped or regulated flow of wastewater to the absorption facility.
Dosing chamber” means a tank/receptacle for retaining effluent until pumped by timing and/or measured volumes to the pressurized absorption facility.
Down gradient” means an area that has a lower potentiometric surface (hydraulic head) than a comparative reference point.
Dwelling” means any structure or building, or any portion thereof which is used, intended, or designed to be occupied for human living purposes including, but not limited to, houses, houseboats, boathouses, mobile homes, manufactured homes, travel trailers, hotels, motels, apartments and condominiums.
Easement” means an interest in land owned by another that entitles its holder to a specific limited use or enjoyment.
Effluent” means the wastewater flow from a tank or treatment process.
Effluent filter” means a device placed in the outlet compartment of a septic tank which conforms to ANSI/NSF Standard 46 for the purpose of removing particulate matter before the effluent enters the absorption facility.
Effluent line” means the pipe beginning at the treatment unit or septic tank and terminating at the absorption facility.
Elevated sand mound” means an on-site wastewater treatment and disposal system which maintains a minimum 36 inches of separation distance above the limiting zone in which wastewater is pressurized into suitable fill material constructed above existing grade.
Emergency permit” means a permit allowing a repair and/or replacement of a broken system component on an emergency basis where immediate action is necessary to protect public health. Repairs/replacements of this kind are considered emergencies occurring when Department offices are closed. Repairs and/or component replacements to cesspools, seepage pits or tank(s) associated with cesspools/seepage pits are not permitted unless approved by the Department.
Encumbrance” means anything non-financial that affects or limits the area available to site, design and install an OWTDS on a property such as easements, right of ways and restrictions. The Department also includes, but is not limited to, these physical encumbrances; dwellings, outbuildings, driveways, or concrete pads.
Engineered sandy fill” means sand that must have a uniformity coefficient of < 5. A minimum of 95% by weight must pass through a #4 sieve and a maximum of 10% by weight through a #100 sieve.
Escarpment” means any naturally occurring slope greater than 30% which extends vertically six (6) feet or more as measured from top to toe, and which is characterized by a long cliff or steep slope which separates two (2) or more comparatively level or gently sloping surfaces, and may intercept one (1) or more layers that limit soil depth.
Existing on‑site wastewater treatment and disposal system” means any installed on‑site wastewater treatment and disposal system constructed in conformance with the rules, laws and local ordinances in effect at the time of construction or which would have conformed satisfactorily to the system design provided for in Department regulations.
Fill” means soil material which has been transported to and placed over the original soil or bedrock and is characterized by a lack of distinct horizons or color patterns as found in naturally developed, undisturbed soils.
Filter aggregate” means washed gravel or crushed stone ranging in size from 3/4" to 2l/2" in any dimension and clean and free of fine materials (dust) and meeting grading specifications in Section 5.4.2.
Filter fabric” means any material approved by the Department which is permeable but does not allow soil particles to pass through for the purpose of protecting the filter aggregate or aggregate free chambers within the absorption facility.
"Food chain crops" means tobacco, crops grown for human consumption, and crops grown to feed animals whose products are consumed by humans.
"Free liquids" means liquids which readily separate from the solid portion of a waste under the following tests:
Full depth gravity” means a gravity fed on-site wastewater treatment and disposal system which maintains a minimum of 36 inches of separation distance above the limiting zone where the trench or bed is generally installed 24 inches into the natural soil.
Governmental appointee” means any state, county, municipal employee or someone contracted by any of these agencies for the purpose of doing official business for the business aspects of the State.
Governmental unit” means the state, any county, municipality, or any part thereof.
GPD” means gallons per day.
Grade” means the inclination or slope of a conduit, ground or plane surface.
Greywater” means the untreated wastewater that has not come into contact with toilet waste. Greywater includes wastewater from bathtubs, showers, bathroom wash basins, clothes washing machines, laundry tubs and other wastewater which does not present a threat from contamination by unhealthy processing, manufacturing or operating wastes. It does not include wastewater from kitchen sinks or dishwashers.
Grease trap” means a watertight tank for the collection and retention of grease which is accessible for periodic removal.
Groundwater” means any water naturally found under the surface of the earth.
High potential for phosphorus mobility” means an area where:
Holding tank” means a watertight receptacle used to store wastewater prior to being removed by a licensed waste hauler.
Hydraulic conductivity” means a specific mathematical coefficient (quantitative) that relates the rate of water movement to the hydraulic gradient. A term of Darcy’s law Q = KAi where K represents hydraulic conductivity and is the current standard for measuring a soils ability to transmit water.
Hydrogeologic suitability report (HSR) means a report that characterizes the hydrogeologic properties present on a given site through direct observations and computer modeling.
Impervious strata and formation” means an underground or surface layer of soil or rock which will not allow water to pass through it at a rate permissible for subsurface disposal and having a percolation rate > 120 minutes per inch.
Infiltrometer” means a device for measuring the rate of entry of liquid into soil; single or double rings that may be read by falling or constant head methods.
Innovative/Alternative treatment and disposal system” means a wastewater treatment and/or disposal system not specified in these regulations which has been proven to provide at least an equivalent level of treatment as the conventional systems as defined in these regulations. Also referred to as alternative technologies.
Interceptor drain” means a gravel trench excavated and installed to collect and remove groundwater. The trench is typically placed across a contour of a slight to moderate sloping area to intercept groundwater at a higher elevation than an on-site wastewater treatment and disposal system.
Invert” means the floor, bottom or lowest portion of the internal cross section of a closed conduit or structure.
Isolation distance” means the horizontal distance between a system component and selected site features or structures.
"Land application" means the placement of liquid waste or treated liquid waste within two (2) feet below the surface of land used to support vegetative growth.
"Land treatment" means a technology for the intimate mixing or dispersion of wastes into the upper zone of the plant-soil system with the objective of microbial stabilization, immobilization, selective dispersion, or crop recovery leading to an environmentally acceptable assimilation of the waste.
Large system” means any on‑site wastewater treatment and disposal system with a projected wastewater design flow rate greater than or equal to 2,500 gallons per day.
Lease” means an agreement by which an owner of property (lessor) transfers the possession, control, use, or enjoyment of the property to another (lessee) for a specified term.
Lessee” means a person who holds the right to possession, control, use, or enjoyment of property by means of an agreement (lease) with the property owner.
Lift package” means a pre-engineered package which includes pump, filter, floats and alarm that is specifically designed to be installed in the liquid (effluent) side of a standard septic tank.
Lift station” means a pre-engineered tank/receptacle package which includes pump, filter, floats and alarm or pre-engineered “lift package” inserted into the liquid (effluent) side of a standard septic tank.  The lift station is designed to overcome slope differentials for pumping effluent to another system component for gravity distribution.
Limited public access” means public access is limited to specific periods of time and spraying activities occur when the public is excluded from accessing the site.
Limiting zone” means any horizon or condition in the soil profile or underlying strata which includes:
"Liquid waste" means any waste which is not a solid waste as defined for the purposes of these Regulations.
Lot” means a portion of a subdivision or parcel of land.
“Low pressure pipe capping fill” means a pressurized on-site wastewater treatment and disposal system which is installed as trenches and maintains a minimum 18 inches of separation distance above the limiting zone. Trenches are installed between 9-17 inches into natural soil below a soil cap of a specified depth and texture.
Low pressure pipe full depth” means a pressurized on-site wastewater treatment and disposal system which is installed as trenches and maintains a minimum 18 inches of separation distance above the limiting zone. Trenches are installed 18 inches into natural soil.
Lysimeter” means an instrument (usually ceramic) for sampling the water percolating through soils that will be used to determine the nutrients and their levels dissolved in the water percolate.
Malfunctioning system” means a system which is not adequately renovating or hydraulically eliminating the wastewater it is receiving as evidenced by, but not limited to, the following conditions:
Manifold” means a pipe with numerous branches to convey effluent between a large pipe and several smaller pipes, or to permit choice of diverting flow from one of several sources or to one of several discharge points.
Manufactured home” means a home built entirely in the factory under a federal building code administered by the Department of Housing and Urban Development (HUD). Manufactured homes may be single or multi-sectioned and are transported to the site and installed.
Mineral soil” means a soil that is saturated with water less than 30 days (cumulative) per year in normal years and contains less than 20% (by weight) organic carbon; or is saturated for greater than 30 days or more cumulative in normal years, and has an organic carbon content (by weight) of less than 18% if the mineral fraction contains 60% or more clay; or less than 12% if the mineral fraction contains no clay.
Monitor well” means a non-potable well used primarily for collecting groundwater samples.
Mottling” means a soil irregularly marked with spots of different colors that vary in number and size which may indicate seasonal or perennial saturation in some part or all of the soil matrix and geogenic in nature.
Non-Hazardous liquid waste” means any industrial waste or sewage or other wastes or any combination thereof which may potentially alter the chemical, physical or biological integrity of water from its natural state. For the purpose of this regulation this includes septage, sewage, grease trap/cooking oil waste, municipal or industrial biosolids, biosolids from package treatment plants, etc.
Observation well” means a non-pumping, non-potable well used for measuring groundwater levels or potentiometric surface.
Offset” means compensating for the loading of a pollutant of concern from a point or nonpoint source with a reduction in the loading from a different source or sources, in a manner consistent with meeting water quality standards.
On‑site wastewater treatment and disposal system” means conventional or innovative/alternative wastewater treatment and disposal systems installed or proposed to be installed on land of the owner or on other land to which the owner has the legal right to install the system.
On-site regulations” means the Regulations Governing the Design, Installation and Operation of On-Site Wastewater Treatment and Disposal Systems.
On-site system advisory board (Board)” means a panel of licensee’s representing the on-site industry, asked to serve by the Secretary, on all matters pertaining to the issuance, suspension, discipline and revocation of all on-site licenses and licensees.
Owner” means the person who has a vested legal or equitable title to real or personal property, including an on‑site wastewater treatment and disposal system.
Percolation rate” means the rate of water movement through a soil. Percolation rate is usually measured and assigned on the basis of elapsed time per unit volumetric water level drop. The most commonly used unit for expressing percolation rate is minutes per inch (mpi).
Performance standard nitrogen level 1 (PSN1)” means where total nitrogen levels achieve either:
Performance standard nitrogen level 2 (PSN2)” means where total nitrogen levels achieve either:
Performance standard nitrogen level 3 (PSN3)” means where total nitrogen levels achieve either:
Performance standard phosphorus level 1 (PSP1)” means where total phosphorus levels achieve either:
Performance standard phosphorus level 2 (PSP2)” means where total phosphorus levels achieve:
Permeability” means the property of a soil horizon that enables the soil to transmit gases, liquid, or other substances.
Permit” means the written document approved by the Department which authorizes the installation of a system or any part thereof, which may also require operation and maintenance of the system.
Permittee” means any individual, partnership, corporation, association, institution, cooperative enterprise, agency, municipality, commission, political subdivision or duly established entity to which a permit is issued.
Person(s)” means any individual, trust, firm, joint stock company, federal agency, partnership, corporation (including a government corporation), association, state, municipality, commission, political subdivision of a state, any interstate body and other legal and commercial entities.
Piezometer” means an alternative word for an observation well.
Platy structure” means soil aggregates that are developed predominantly along the horizontal axis, laminated and flaky; commonly used to indicate compaction on many coastal plain soils.
Pollution or water pollution” means any alteration of the physical, chemical or biological properties of any waters of the state, including change in temperature, taste, color, turbidity, silt or odor of the waters, or such discharge of any liquid, gaseous, solid, radioactive or other substance into any waters of the state, which will or tends to, either by itself or in connection with any other substance, create a public nuisance or which will or tends to render such waters harmful, detrimental or injurious to public health, safety or welfare, or to domestic, commercial, industrial, agricultural, recreational or other legitimate beneficial uses or to livestock, wildlife, fish or other aquatic life or the habitat thereof.
Potentiometric surface” means a surface that represents the level to which water will rise in tightly cased wells.
Pressure-dosed capping fill” means a pressurized on-site wastewater treatment and disposal system which maintains a minimum 36 inches of separation distance above the limiting zone where the trench or bed is installed between 12 and 23 inches into the natural soil below a soil cap of a specified depth and texture.
Pressure-dosed full depth” means a pressurized on-site wastewater treatment and disposal system which maintains a minimum 36 inches of separation distance above the limiting zone where the trench or bed is installed 24 inches into the natural soil.
Pressurized distribution” means a network of piping with orifices designed to evenly distribute wastewater under pressure through the entire absorption facility.
Primary treatment” means a wastewater treatment process that takes place in a tank and allows those substances in wastewater that readily settle or float to be separated from the water being treated.
Professional engineer” means a person registered by the Delaware Association of Professional Engineers to practice professional engineering in the State of Delaware.
Professional geologist” means a person registered by the Delaware State Board of Professional Regulation to practice professional geology in the State of Delaware.
Professional soil scientist/soil classifier” means a person registered by the ARCPACS (a federation of certifying boards in Agriculture, Biology, Earth and Environmental Sciences) to practice professional soil science in the State of Delaware.
Project site” means the total area within the property lines of an individual lot or within the division lines of a parcel or subdivision.
Public health hazard” means a condition whereby there are sufficient types and amounts of biological, chemical or physical, including radiological, agents relating to water or sewage which are likely to cause human illness, disorders or disability. These include, but are not limited to, pathogens, viruses, bacteria, parasites, toxic chemicals, and radioactive isotopes.
Public service commission” means an agency created to regulate investor-owned public utilities. The Delaware Public Service Commission (PSC) works to ensure safe, reliable and reasonably priced cable, electric, natural gas, wastewater, water and telecommunications services for Delaware consumers.
Rapid infiltration basins” means earthen basins designed for a repetitive cycle of flooding, infiltration/percolation, and drying of treated wastewater.
Redoximorphic features” means characteristic soil patterns formed by the reduction, translocation and oxidation of iron and manganese oxides. The occurrence of these features may be indicative of seasonal or perennial saturation in some part or the entire soil matrix.
Reducing condition” means a geochemical condition where dissolved oxygen is depleted (< 1 mg/L).
Regeneration water” means all water consumed in the regeneration steps: backwash, regeneration (brining), dilution (and brine displacement), and rinse. Raw water or treated water may be used for the rinse down.
Regional wastewater treatment and disposal facility” means a large on-site wastewater treatment and disposal system which serves any entity within the designated service area(s) approved by the Public Service Commission.
Repair” means any modification to an existing on-site wastewater treatment and disposal system necessary to fix a problem or malfunction.
Replacement system” means a new on-site wastewater treatment and disposal system to replace the existing on-site wastewater treatment and disposal system or a portion thereof.
Responsible party” means the person, corporation, owner, utility or other entity that will assume full financial and operational control of the facility.
Sand” means individual mineral particles in a soil that range in diameter from the upper limit of silt (0.05 millimeters to 2.0 millimeters).
Sand-lined system” means a type of seepage trench or seepage bed absorption facility constructed in the sandy fill material below the natural soil surface and may require pressurization. The sandy fill material is used to replace a natural impermeable or slowly permeable soil layer or to completely remove an existing absorption facility.
Sandy fill” means materials that consist of medium sand, sandy loam, loamy sand/sandy loam mixtures.
Scarifying” means scraping or loosening the bottom and sidewall soil surfaces in the preparation of percolation test holes, seepage trenches, beds, or similar excavations.
Scum” means a mass of sewage solids floating at the surface of effluent and buoyed up by entrained gas, grease or other substances.
Seasonal high water table” means the highest zone of soil or rock that is seasonally or permanently saturated by a perched or shallow water table. A planar surface, below which all pores in rock or soil (whether primary or secondary) that is seasonally or permanently saturated.
Secondary treatment” means a combination of unit processes that will consistently remove 85% or more of the organic and suspended material in domestic wastewater and produce an effluent of sufficient quality to satisfy the following requirements; monthly average effluent BOD5 and TSS concentrations of 30 mg/L; daily maximum effluent BOD5 and TSS concentrations of 45 mg/L.
Secretary” means the Secretary of the Department of Natural Resources and Environmental Control or a duly authorized designee.
Seepage bed” means an absorption facility consisting of an area from which the entire earth contents have been removed and replaced with a network of perforated pipe, filter aggregate or aggregate-free chambers and covered with suitable backfill material.
Seepage pit” means a covered pit with a porous lining into which wastewater is discharged and allowed to seep or leach into the surrounding soil and is preceded by a septic tank. Note: seepage pits cannot be certified for real estate transfers.
Seepage trench” means an absorption facility consisting of ditches with vertical sides and flat bottoms partially filled with filter aggregate and containing perforated pipe or aggregate-free chambers and covered with suitable backfill material.
Septage” means the liquid and solid contents of a septic tank.
Septic tank” means a watertight receptacle which receives the discharge of wastewater from a structure or part thereof and is designed and constructed so as to permit settling of solids from the liquid, digestion of the organic matter by detention, and discharge of the liquid portion into an absorption facility.
"Sewage" means water-carried human or animal wastes from septic tanks, water closets, residences, buildings, industrial establishments, or other places, together with such groundwater infiltration, subsurface water, admixture of industrial wastes or other wastes as may be present.
"Sewage sludge" means sludges which derive in whole or in part from sewage.
Single family dwelling” means a residence intended for single family residential use.
Site evaluation” means the practice of investigating, evaluating and reporting basic soil and site conditions which apply to the on‑site wastewater treatment and disposal system type and design criteria.
Slope” means the deviation of a plane surface from the horizontal. It is usually expressed as a ratio or percentage of number of units of vertical rise or fall per unit of horizontal distance.
"Sludge" means the accumulated semi-liquid suspension, settled solids, or dried residue of these solids that is deposited from (a) liquid waste in a municipal or industrial wastewater treatment plant, (b) surface or groundwaters treated in a water treatment plant, whether or not these solids have undergone treatment. Septage is included herein as sludge.
Small system” means any on‑site wastewater treatment and disposal system with a projected wastewater design flow rate < 2,500 gallons per day.
Soil feasibility study” means a site/soil investigative report identifying the suitability of a parcel of land for a large, community or individual on-site wastewater treatment and disposal systems. The report includes information pertinent to the Department and other local government agencies in the determination of certain land use decisions.
Soil horizon” means a layer of soil or soil material approximately parallel to the land surface and differing from adjacent genetically related layers in physical, chemical, and biological properties or characteristics such as color, structure, texture, consistence and pH.
Soil investigation report (SIR) means a report that characterizes the soils present on a given site through direct observations and analysis.
Soil profile” means a vertical cross-section of a soil that shows the various soil horizons. Soil drainage or moisture status are both soil characteristics that can be inferred from the soil profile.
Soil structure” means the combination or arrangement of primary soil particles into secondary compound particles or clusters, the principle forms of which are: platy (laminated); prismatic (prisms with rounded tops); blocky (angular or subangular); granular and columnar.
Soil texture” means the grain sizes that comprise a soil consisting of three textural classes; sand, silt and clay. Field methods for judging the texture of a soil consist of forming a cast of soil, both dry and moist, in the hand and pressing a ball of moist soil between thumb and finger.
Sand: Individual grains can be seen and felt readily. Squeezed in the hand when dry, this soil will fall apart when the pressure is released. Squeezed when moist, it will form a cast that will hold its shape when the pressure is released, but will crumble when touched.
Sandy Loam: Consists largely of sand, but has enough silt and clay present to give it a small amount of stability. Individual sand grains can be readily seen and felt. Squeezed in the hand when dry, this soil will readily fall apart when the pressure is released. Squeezed when moist, it forms a cast that will not only hold its shape when the pressure is released, but will withstand careful handling without breaking. The stability of the moist cast differentiates this soil from sand.
Loam: Consists of an even mixture of sand and of silt and a small amount of clay. It is easily crumbled when dry and has a slightly gritty yet fairly smooth feel. It is slightly plastic. Squeezed when moist, it forms a cast that will not only hold its shape when the pressure is released, but will withstand careful handling without breaking. The stability of the moist cast differentiates this soil from sand.
Silt Loam: Consists of a moderate amount of fine grades of sand, a small amount of clay, and a large quantity of silt particles. Lumps in a dry, undisturbed state appear quite cloddy, but they can be pulverized readily; the soil then feels soft and floury. When wet, silt loam runs together in puddles. Either dry or moist, casts can be handled freely without breaking. When a ball of moist soil is pressed between thumb and finger, it will not press out into a smooth, unbroken ribbon, but will have a ribbon appearance.
Clay Loam: Consists of an even mixture of sand, silt, and clay, which breaks into clods or lumps when dry. When a ball of moist soil is pressed between the thumb and finger, it will form a thin ribbon that will readily break, barely sustaining its own weight. The moist soil is plastic and will form a cast that will withstand considerable handling.
Silty Clay Loam: Consists of a moderate amount of clay, a large amount of silt, and a small amount of sand. It breaks into moderately hard clods or lumps when dry. When moist, a thin ribbon or one eighth (1/8) inch wire can be formed between thumb and finger that will sustain its weight and will withstand gentle movement.
Silty Clay: Consists of even amounts of silt and clay and very small amounts of sand. It breaks into hard clods or lumps when dry. When moist, a thin ribbon or one eighth (1/8) inch or less sized wire formed between thumb and finger withstand considerable movement and deformation.
Clay: Consists of large amounts of clay and moderate to small amounts of sand. It breaks into very hard clods or lumps when dry. When moist, a thin, long ribbon or one sixteenth (1/l6) inch wire can be molded with ease. Fingerprints will show on the soil, and a dull to bright polish is made on the soil by a shovel.
Silt: Consists largely of silt with very small amounts of clay. The soil feels very silky or floury. When pressed between thumb and finger it will readily pulverize without forming a ribbon.
Loamy Sand: Is predominately composed of sand, but has enough clay so that it can be formed into a weakly developed ball with careful handling.
Sandy Clay Loam: The predominant particle size found within this soil textural class is sand, although it contains relatively high levels of clay with lesser amounts of silt. When moist, it will form a thin ribbon that does not readily break.
Sandy Clay: Consists of relatively even amounts of sand and clay with very small amounts of silt. When moist, a thin ribbon can readily be formed between thumb and finger without considerable deformation or movement.
"Solid waste" means any garbage, refuse, rubbish, and other discarded materials resulting from industrial, commercial, mining, agricultural operations and from community activities which does not contain free liquids. Containers holding free liquids shall be considered solid waste when the container is designed to hold free liquids for use other than storage (e.g. radiators, batteries, transformers) or the waste is household waste which is not sewage or septage.
Solum” means the upper part of the soil profile (A, E and B horizons) above the parent material in which the processes of soil formation are active.
Spare area” means an area set aside for construction of a second absorption facility with the equivalent design capacity of the operational absorption facility to be used in the event the operational absorption facility becomes inoperable.
"Spray irrigation" means the controlled application of treated wastewater to a vegetated soil surface.
"Storage" means the interim containment of liquid waste or treated liquid waste before disposal or utilization.
Subdivision” means any tract or parcel of land which has been divided into two or more lots for which development is intended.
"Surface impoundment" means a natural topographic depression, and/or man-made excavation, and/or diked area formed primarily of earthen materials (although it may be lined with man-made materials) or remains unlined, and which is designed to hold an accumulation of liquid wastes or wastes containing free liquids. Examples of surface impoundments are holding, storage, settling, and elevation pits, ponds, and lagoons.
Surface water assessment report (SWAR)” means a report that characterizes the potential nutrient impacts of a wastewater treatment system to a site from future development through background data and computer modeling.
System” means an on‑site wastewater treatment and disposal system.
System inspector” means a person licensed by the Department to inspect, investigate, collect data and make determinations regarding the present operational condition of an on-site wastewater treatment and disposal system.
System operator” means an individual, who at a given time, through observation, interpretation or decision operates a wastewater facility or a segment of a system or facility.
Tertiary treatment” means the removal of pollutants, including nitrogen and phosphorus, to meet discharge or reuse criteria with respect to specific parameters and followed by disinfection.
Test pit” means an excavation used to examine a soil profile in order to assess soil permeability and depth to a seasonal high water table using soil texture, structure, and redoximorphic features as a basis for assessing site suitability.
Topography” means ground surface variations or contours of the earth's surface, both natural and anthropogenic.
Total nitrogen” means the sum of all the forms of nitrogen; ammonia, ammonium, nitrate, nitrite and organic nitrogen present in wastewater.
Total phosphorus” means the sum of the water soluble and citrate-insoluble phosphorus present in wastewater.
Total suspended solids (TSS)” means a measure of the suspended solids in wastewater, effluent, or water bodies, determined by tests for “total suspended non-filtered solids.”
"Treatment" means a process which alters, modifies or changes the biological, physical or chemical characteristics of sludge or liquid waste.
"Treatment works" means any device and system used in the storage, treatment, recycling and reclamation of municipal sewage, or industrial wastes of a liquid nature, or necessary to recycle or reuse water at the most economical cost over the estimated life of the works, including intercepting sewers, outfall sewers, sewage collection systems, pumping, power and other equipment, and their appurtenances, extensions, improvements, remodeling, additions and alterations thereof; elements essential to provide a reliable recycled supply such as standby treatment units and clear well facilities and improvements to exclude or minimize inflow and infiltration.
Unconfined aquifer” means an aquifer in which a relatively impermeable layer does not exist between the water table and the ground surface and in which the water surface is at atmospheric pressure.
Undisturbed soil” means soil or soil profile unaltered by filling, removal, or other man‑made changes with the exception of agricultural activities.
Unlimited public access” means public access to the site may occur at any time.
Upgradient” means an area that has a higher potentiometric surface (hydraulic head) than a comparative reference point.
Wastewater” means water‑carried waste from septic tanks, water closets, residences, buildings, industrial establishments, or other places, together with such groundwater infiltration, subsurface water and mixtures of industrial wastes or other wastes as may be present.
"Wastewater treatment plant" means a facility designed and constructed to receive, treat, or store waterborne or liquid wastes.
Wastewater utility” means any person, partnership, association, corporation, joint stock company, agency or department of the State or any association of individuals engaged in the business of providing wastewater disposal and related services to the public for a fee, charge, or other remuneration in the State of Delaware.
Watercourse” means any ocean, bay, lake, pond, stream, river or defined ditch that will permit drainage into any surface water body, excluding ephemeral watercourses as defined below.
Water softener backwash” means the wastewater by-product generated by the water softening process (see regeneration water).
Watershed” means a region or area delineated by a topographical divide and draining ultimately to a particular watercourse.
Water table” means the surface of an unconfined aquifer where the pore water pressure is equal to atmospheric pressure.
Waters of the state” means public waters, including lakes, bays, sounds, ponds, impounding reservoirs, springs, wells, rivers, streams, creeks, estuaries, marshes, inlets, canals, the ocean within the territorial limits of the State, and all other bodies of surface or groundwater, natural or artificial, inland or coastal, fresh or salt, within the jurisdiction of the State of Delaware.
Well” means any excavation which intersects the water table, and is installed for the purpose of obtaining geologic or hydrologic information and for locating, testing, measuring, extracting, and/or recharging water and other fluids, and where the depth is greater than the width. Such excavations may have been drilled, augered, cored, bored, driven, dug, jetted, or otherwise constructed. This definition does not include excavations for utility poles, construction pilings, building foundations, fence posts, test pits, or horizontal heat pump systems that are constructed above the water table.
Wisconsin at-grade” means a pressurized on-site wastewater treatment and disposal system which maintains a minimum 24 inches of separation distance above the limiting zone placed on the natural soil below a soil cap of a specified depth and texture.
Zone of aeration” means a subsurface zone containing water under pressure less than that of the atmosphere, including water held by capillary and containing air or gases generally under atmospheric pressure. This zone is limited above by the land surface and below by the surface of the zone of saturation, e.g., the water table.
 
3.0 General Standards, Prohibitions and Provisions
3.1 Each and every owner of real property is jointly and severally responsible for:
3.1.1 Disposing of wastewater in conformance with all applicable regulations; and
3.1.2 Connecting all plumbing fixtures on that property, from which wastewater is or may be discharged, to a central wastewater system or on‑site wastewater treatment and disposal system approved by the Department; and
3.1.3 Maintaining, repairing, and/or replacing the system as necessary to assure proper operation of the system.
3.2 No permit may be issued by the Department under these Regulations unless the county or municipality having land use jurisdiction has first approved the activity through zoning procedures provided by law.
3.3 Any governmental unit may assume responsibility and authority for administering its own regulatory program for on‑site wastewater treatment and disposal systems pursuant to 7 Del.C. §6003(d) if the delegated program establishes standards no less stringent than the standards established in these Regulations.
3.4 Administrative and judicial review and the enforcement under these Regulations shall be in accordance with the provisions of 7 Del.C. Ch. 60.
3.5 If any part of these Regulations, or the application of any part thereof, is held invalid or unconstitutional, the application of such part to other persons or circumstances, and the remainder of these Regulations, shall not be affected thereby and shall be deemed valid and effective.
3.6 These Regulations, being necessary for the health and welfare of the State and its inhabitants, shall be liberally construed in order to preserve the land, surface water and groundwater resources of the State.
3.7 At the sole discretion of the Department, if the proposed operation of a system may cause pollution of public waters or create a public health hazard, system installation or use shall not be authorized.
3.7.1 In no case shall an active OWTDS be installed over or dispose of wastewater on top of an existing OWTDS without sand-lining or properly abandoning the old system.
3.8 All wastewater shall be treated and disposed of in a manner approved by the Department.
3.9 No person shall dispose of wastewater at any location other than those authorized by the Department under applicable laws and regulations for such disposal.
3.10 Discharge of untreated or partially treated wastewater or septic tank effluent directly or indirectly onto the ground surface or into groundwater and/or surface waters of the State, unless authorized by a permit issued by the Department, constitutes a public health hazard and is prohibited.
3.11 Except where specifically allowed within these Regulations, no person shall connect a dwelling or commercial facility to a system if the total projected wastewater flow would be greater than that allowed under the original system construction permit. In no case shall more than one reduction (low flow, advanced treatment, or gravel-less chambers) be used in determining minimal absorption facility sizing requirements.
3.12 Except as provided in these Regulations, the spare area shall be kept vacant, free of site improvements, livestock, vehicular traffic (including construction trafficking) and soil modifications.
3.13 All systems shall be operated and maintained so as not to create a public health hazard or cause water pollution.
3.14 The Department shall have the power to enter, at reasonable times, upon any private or public property for the purpose of inspecting and investigating conditions relative to the enforcement of these Regulations in accordance with 7 Del.C. §6024.
3.15 No person shall cause or allow construction or repair of a system, or any part thereof, without a permit issued by the Department. An exception may be allowed for certain emergency repairs as set forth in these Regulations.
3.16 The Department shall impose, in any permit, standards for evaluating treatment system performance and compliance with these Regulations. The standards may be in the form of limitations on flow and pollutant concentrations and/or mass loadings. The standards shall reflect the utilization of best management and operational practices.
3.16.1 When performance standards have not been achieved on an annual average basis after the appropriate system start-up period, as defined in the regulations and/or applicable on-site system permit, those persons may qualify to participate in a nutrient offset program subject to review and approval by the Department on a site specific basis.
3.17 In no cases will underdrains or artificial drainage be considered for the siting of any on-site wastewater treatment and disposal system.
3.18 In the event that these regulations are revised by the Department, permits may be reopened and modified accordingly after notice and opportunity for a public hearing.
3.19 The permittee shall at all times properly maintain and operate all structures, systems, and equipment for treatment, control and monitoring, which are installed or used by the permittee to achieve compliance with the permit and these Regulations.
3.20 The permittee shall take all necessary actions to eliminate and correct any adverse impact on public health or the environment resulting from permit noncompliance.
3.21 All electrical connections and components utilized in an OWTDS, must, at a minimum, comply with National and Delaware Electric Code (Admin Code, Title 24, §1400).
3.22 FEMA guidelines must be adhered to when siting OWTDS’ in flood prone areas designated as “V” zones prior to permitting.
3.22.1 Certification by a registered professional engineer (Class C) that all new and replacement on-site wastewater treatment and disposal systems, including holding tanks, are located and designed to minimize or eliminate flood damage, infiltration of floodwaters into the tank and discharges from the system into floodwaters. New and replacement on-site wastewater treatment and disposal systems shall be located so as to minimize alterations to sand dunes which would increase potential flood damage.
3.23 Moratorium Areas
3.23.1 When the Department determines that construction of on-site wastewater treatment and disposal systems should be limited or prohibited in an area, it shall issue an order limiting or prohibiting such construction.
3.23.2 The order shall be issued only after a public hearing which shall insure that 20 days notice is given.
3.23.3 The order shall contain a specific description of the moratorium area and shall be limited to the area immediately threatened with groundwater or surface water contamination if construction in that area continues.
3.23.4 In issuing an order under this Section the Department shall consider the factors contained in 7 Del.C. §6001.
3.23.5 The moratorium shall be limited to a period of five (5) years after which re-establishment of the moratorium may be considered.
3.24 Whenever the preparation of reports or other documents required by these regulations involves the practice of engineering, geology or other recognized profession under Delaware law, sufficient evidence of appropriate certification or registration in accordance with 24 Del.C. must be submitted by the preparer.
3.24.1 In accordance with 29 Del.C. §§501 et seq., retention of reports or other documents may be paper and/or electronic records.
3.25 All Occupational Safety and Health Act (OSHA) regulations must be complied with during all phases of system installation and inspection. OSHA regulations can be found at www.osha.gov or by contacting the U.S. Department of Labor.
3.26 Enforcement
3.26.1 The provisions of these regulations shall be enforced by the Department as provided in 7 Del.C. Ch. 60. Such enforcement may include suspension or revocation of any license for cause.
3.26.2 The failure of the Department to enforce any of the provisions of these regulations shall not constitute a waiver by the Department of such provisions.
3.27 Exhibits A through NN are incorporated into these Regulations by reference.
3.28 The Department continues to encourage development of new systems, processes, and techniques for eliminating, reusing, or recovering resources from wastewater.  These techniques include, but are not limited to greywater collection and use, nutrient recovery, and source reduction of wastewater.  These innovative technologies are subject to review and approval by the Department.
3.29 Number of Plan Reviews
3.29.1 The Department will review no application more than three (3) times. If after the third review the plan is not approved, the application will be denied, and the reasons for plan denial will be sent to the applicants.
3.29.2 In order for a plan to be reconsidered, the Department may, at its discretion:
3.29.2.1 Require a new application package and review fee in order to continue to review the application. The second application will be reviewed no more than three (3) additional times.
3.30 All new and replacement systems permitted within 1,000 feet of the Chesapeake Bay tidal waters as displayed by the map in Exhibit NN shall meet the Performance Standards for Nitrogen and Phosphorus as defined in these Regulations (see Exhibit MM).  This requirement shall become effective one (1) year from the date of promulgation of these Regulations.
3.31 General Standards, Prohibitions and Provisions for small systems (< 2,500 gpd) only
3.31.1 No person shall construct, install, modify, rehabilitate, or replace an on‑site wastewater treatment and disposal system or construct or place any dwelling, building, mobile home, manufactured home or other structure capable of discharging wastewater on‑site unless such person has a valid permit issued by the Department pursuant to these Regulations.
3.31.2 Each system shall have adequate capacity to properly treat and dispose of the maximum projected daily wastewater flow. The projected quantity of wastewater must be determined from Exhibit D. Other projected wastewater quantities may be approved by the Department.
3.31.3 A recorded utility easement is required whenever a system crosses a property line separating property under different ownership. The easement must accommodate that part of the system, including setbacks, which lies beyond the property line, and must allow entry to install, maintain and repair the system.
3.31.4 No cooling water, air conditioning water, groundwater, oil, water softener backwash (regeneration water) or roof drainage shall be discharged into any system without specific authorization of the Department.
3.31.5 If a site has received an approved site evaluation and is free of encumbrances which could prevent the installation or operation of the system from being in conformance with these Regulations then a permit may be issued.
3.31.6 Whenever real property is recorded as two separate lots under common ownership and an on‑site wastewater treatment and disposal system crosses the common boundary of the recorded lots, the owner shall execute and record, in the appropriate county office of Recorder of Deeds, an affidavit which notifies prospective purchasers of this fact on a form approved by the Department.
3.31.7 No person shall transfer any portion of real property if the transfer would create a lot boundary which would cross an existing system or any part thereof including required setbacks and isolation distances unless a utility easement approved by the Department is granted to the owner of the existing system and recorded in the appropriate county office of Recorder of Deeds.
3.31.8 No person shall transfer any portion of real property after the issuance of a permit pursuant to these Regulations if the transfer would result in the use of the permitted on‑site system on a lot which does not comply with these Regulations and the terms of the permit, including but not limited to density, set back and isolation distance requirements.
3.31.9 A central wastewater system shall be deemed physically available if its nearest connection point from the property line or boundary to be served is:
3.31.9.1 For all single family dwellings or establishments within 200 feet;
3.31.9.2 For a proposed subdivision or group of two (2) to five (5) single family dwellings not further than 200 feet multiplied by the number of dwellings or dwelling equivalents.
3.31.9.3 For proposed subdivision or other developments with more than five (5) single family dwellings, or equivalents, the determination of central wastewater availability shall be at the sole discretion of the Department.
However, a central wastewater system shall not be considered available by the Department if topographic or manmade features make connection impossible or a waiver is obtained from the municipality or governmental authority.
3.31.10 A central wastewater system shall be deemed legally available if the system is not under a Department connection permit moratorium and the wastewater system owner is willing or obligated to provide sewer service.
3.31.11 When a central wastewater system is deemed both physically and legally available, as outlined in Sections 3.31.9 and 3.31.10, the connection must occur within a timeframe as set forth by the wastewater system owner. The existing system must be abandoned in accordance with Section 5.4.8.
3.31.12 All cesspools and seepage pits are prohibited and when found must be replaced within one (1) year in accordance with these regulations.
3.31.13 For all properties utilizing an OWTDS that are sold or otherwise transferred to other ownership, the persons must have the system pumped out and inspected by a Class F and Class H licensee, respectively, prior to completion of the sale. All inspections of on-site wastewater treatment and disposal systems shall be submitted to the Department on forms approved by the Department (see Exhibit A). These forms shall be submitted within 72 hours of inspection completion.
3.31.13.1 For transfers of new property, the certificate of completion will suffice if issued within the previous 24 months, or;
3.31.13.2 If an inspection has occurred within the previous 36 months and the property owner can provide proof of the pump out and inspection and the system is not a cesspool or seepage pit, then the inspections referred to in Section 3.31.13 will suffice, or;
3.31.13.3 If the owner of an individual OWTDS provides proof of a licensed operator or has a service contract with a certified service provider then the requirements referred to in Section 3.31.13 have been met.
3.31.14 Timers or other electrical on/off delay devices shall be installed on all pressurized systems to ensure dosing frequencies and volumes. Appliance timers are not acceptable.
3.31.15 Siting Density
3.31.15.1 The following maximum siting densities shall be maintained:
3.31.15.1.1 For residential dwellings, the maximum siting density shall be one (1) dwelling unit per one half (1/2) acre.
3.31.15.1.1.1 For single family residences, only the area within the property lines of the lot shall be considered.
3.31.15.1.1.2 For multiple family dwellings or where more than one (1) dwelling is to be served by an on‑site wastewater treatment and disposal system, the maximum siting density shall be based on the net pervious area (e.g., unpaved, without structures) available for groundwater recharge after total project completion. The following criteria shall be utilized in determining the maximum siting densities:
3.31.15.1.1.2.1 For projects utilizing only a septic tank for treatment prior to discharge to the absorption facility, the maximum siting density shall be one (1) dwelling unit per one half (1/2) acre of pervious area.
3.31.15.1.2 For commercial facilities the maximum siting density shall be established by dividing the projected design flow by 500 gallons per day per one half (1/2) acre and shall be based on the net pervious area (e.g., unpaved, without structures) available for groundwater recharge after total project completion. Campgrounds intended for overnight or transient use are evaluated as commercial facilities as opposed to manufactured home communities, which are evaluated as single family residential facilities.
3.31.15.1.3 In establishing maximum siting densities the Department may consider impervious areas where it can be demonstrated that through the establishment of an acceptable stormwater management plan, all runoff will be recharged to the groundwater of the State within the boundaries of the project site. Stormwater management plans shall be based upon the sediment and stormwater regulations.
3.31.15.2 If the deed or instrument, under which an owner acquired title to a lot or parcel, was of record prior to April 8, 1984 and if such lot or parcel does not conform to the requirements of Section 3.31.15.1.1, then the Department may approve a feasibility study and/or issue a construction permit for an on‑site wastewater treatment and disposal system. This system is to serve a single family dwelling or for multiple systems to serve dwellings to be situated within an area which has been given final site plan approval prior to April 8, 1984 for single or multi‑family dwellings provided that:
3.31.15.2.1 The number of dwelling units per net pervious area (e.g., unpaved, without structures) does not increase from those approved prior to April 8, 1984 by the local governmental unit having jurisdiction; and
3.31.15.2.2 At the time the permit is issued or feasibility study is approved, the lot or parcel complies with the requirements of Section 3.0 through Section 6.0 of these Regulations.
When it may be necessary to increase the net pervious area or reduce the number of dwelling units within a lot or parcel and thus create a new date of recordation or final site plan approval, the Department shall utilize the previous date of recordation or approval in determining conformance with these Regulations. The owner shall provide, prior to any action by the Department, all documentation determined by the Department to be necessary in establishing conformance with this Section.
3.31.16 All new and replacement small systems requiring advanced treatment units must adhere to the performance standard nitrogen level 3 (PSN3). These performance standards shall become effective one (1) year from date of regulation promulgation.
3.32 General Standards, Prohibitions and Provisions for large systems (≥ 2,500 gpd) only
3.32.1 Whenever the preparation of reports or other documents required by these regulations involves the practice of engineering, geology or other recognized licensed profession under Delaware law, sufficient evidence of appropriate certification or registration in accordance with 24 Del.C. shall be dated and bear the signature and seal of the licensee(s) who prepared or approved them.
3.32.2 For large systems which serve communities that experience a significant variation in flow on an annual basis, the permittee shall provide the Department with specific criteria in the permit for taking certain treatment units out of service during periods of low flow. The criteria will establish procedures for winterization, restart and the minimum levels of treatment which must be provided at all times. In no event shall it be less than the level of treatment provided by a conventional on-site wastewater treatment and disposal system.
3.32.3 Unless otherwise required by a permit the permittee and operator, if applicable, must coordinate with the Department for all annual large system inspections and applicable fees.
3.32.4 The basic performance criteria for a large system are: (a) primary and secondary drinking water standards for groundwater and surface waters are not exceeded, (b) the system does not present a public health problem, and (c) the soil is not degraded so as to prevent future use for agriculture, forestry or other planned development.
3.32.5 To protect groundwater quality, concentrations of wastewater constituents must not exceed allowable limits as stipulated in the National Interim Primary and Secondary Drinking Water Regulations.
3.32.6 The permittee shall furnish to the Department within a specified period of time, any information including copies of records, which may be requested by the Department to determine whether cause exists for modifying, revoking, reissuing, or terminating the permit, or to determine compliance with the permit and these Regulations.
3.32.7 The permittee shall allow the Department entry and access, consistent with 7 Del.C. Ch. 60, to:
3.32.7.1 Enter the permitted facility.
3.32.7.2 Inspect any records that must be kept under the conditions of the permit.
3.32.7.3 Inspect any facility, equipment, practice, or operation permitted or required by the permit.
3.32.7.4 Sample or monitor for the purpose of assuring permit compliance of any substance or any parameter at the facility.
3.32.7.5 The permittee shall report to the Department under the circumstances and in the manner specified in this Section:
3.32.7.5.1 In writing 30 days before any planned physical alteration or addition to the permitted facility or activity if that alteration or addition would result in any significant change in information that was submitted during the permit application process.
3.32.7.5.2 In writing 30 days before any anticipated change which would result in noncompliance with any permit condition or these regulations.
3.32.7.5.3 Orally within 24 hours from the time the permittee became aware of any noncompliance which may endanger the public health or the environment at telephone numbers provided in the permit by the Department.
3.32.7.5.4 In writing as soon as possible but within five (5) days of the date the permittee knows or should know of any noncompliance unless extended by the Department. This report shall contain:
3.32.7.5.4.1 A description of the noncompliance and its cause;
3.32.7.5.4.2 The period of noncompliance including to the extent possible, times and dates and, if the noncompliance has not been corrected, the anticipated time it is expected to continue; and
3.32.7.5.4.3 Steps taken or planned to reduce or eliminate reoccurrence of the noncompliance.
3.32.7.5.5 In writing as soon as possible after the permittee becomes aware of relevant facts not submitted or incorrect information submitted, in a permit application or any report to the Department. Those facts or the correct information shall be included as a part of this report.
3.32.8 All new large systems, except spray, must adhere to the performance standards below, as applicable to its permitted daily design flow. The > 300,000 gpd requirement is for Rapid Infiltration Basins (RIB) only. This requirement becomes effective six (6) months from date of promulgation of these regulations. The performance standards are as follows:
3.32.9 All new spray irrigation facilities must adhere to the following performance standards at the point of compliance, the lysimeter. The performance standards are as follows: