Dolby and Associates, Inc.
22183 Sussex Hwy
Seaford, DE 19973
Phone: 302-629-0314
Fax: 302-629-2872
Dolby and Associates Septic System Services Other Services

Septic System Basics


Steps Required When You Need A Septic

The steps for installing a new or replacement septic system in Delaware are as follows:

  • Have a Class D Soil Scientist perform a site evaluation to determine the percolation rate and the type of septic system required.
  • Have a Class C Designer design the septic system based on the information provided by the Soil Scientist and prepare a septic permit application for submission to DNREC. If it is a gravity septic system then a Class B designer can design the system.
  • Have a Class E System Contractor install the system after DNREC issues the permit.
  • If it is an Innovative/Alternative (I/A) system, sign a contract with an Operation and Maintenance Service Provider (O&M) to perform the required operation and inspection activities for the life of the system. Some examples of I/A systems are peat biofilter, micro-irrigation (drip), or one of several types of pretreatment systems approved by DNREC. The O&M provider must be certified by the equipment manufacturer and licensed by DNREC. I/A systems are required in the Inland Bays and Nanticoke River watershed in Sussex County.

Useful Quotes From DNREC Regulations

Wastewater treatment and disposal systems in the State of Delaware are regulated by the Department of Natural Resources and Environmental Control usually referred to as DNREC. The applicable regulations are titled “Regulations Governing The Design, Installation And Operation Of On-Site Wastewater Treatment And Disposal Systems”. Some useful excerpts from those regulations are as follows:

Definitions:

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 (ATU) 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.

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 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 a Class E system contractor or Class H system inspector license; or
  • A Class E system contractor who is certified, through DNREC approved training, on the operation and maintenance of the advanced treatment unit or system; or
  • A Class H system inspector who has become certified through DNREC approved training on the operation and maintenance of the advanced treatment unit or system; or
  • A Homeowner who has obtained DNREC individual homeowner service provider certification and has been certified through DNREC approved training on the operation and maintenance of the advanced treatment unit or system. The DNREC homeowner certification allows the homeowner to operate and maintain their Innovative/Alternative system at their primary residence only.

Cesspool means a covered pit, with a porous lining, into which wastewater is discharged and allowed to seep or leech 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.

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.

Elevated Sand Mound (ESM) means an on-site wastewater treatment and disposal system which maintains a minimum 36” of separation distance above the limiting zone in which wastewater is pressurized into suitable fill material constructed above existing grade.

Full Depth Gravity means a gravity fed on-site wastewater treatment and disposal system which maintains a minimum of 36” of separation distance above the limiting zone where the trench or bed is generally installed 24 inches into natural soil.

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 pressured 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” into natural soil.

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:

  • Failure of a system to accept wastewater discharge or the backup of wastewater into the structure served by the system
  • Direct discharge of wastewater to the surface of the ground, surface water, or groundwater without adequate renovation.
  • Percolation Rate means the rate of water movement through 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 3 (PSN3) means where total nitrogen levels achieve either:
  • An average annual concentration of 20 mg/l (ppm) total nitrogen in effluent sampled at the end-of-pipe of the advanced treatment unit; or
  • A 50% reduction in effluent total nitrogen concentration when compared to the influent total nitrogen concentration at the end-of-pipe of the advanced treatment unit; or
  • A 50% reduction in effluent total nitrogen concentration when compared to the influent total nitrogen concentration beneath any permitted on-site wastewater treatment and disposal system as verified by in-field monitoring or third party test results.

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.

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