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The Pennsylvania Code website reflects the Pennsylvania Code changes effective through 54 Pa.B. 1806 (March 30, 2024).

25 Pa. Code § 73.71. Experimental sewage systems.


§ 73.71. Experimental sewage systems.

 (a)  Experimental systems may be considered for individual or community systems in any of the following cases:

   (1)  To solve an existing pollution or public health problem.

   (2)  To overcome specific site suitability deficiencies, or as a substitute for systems described in this chapter on suitable lots.

   (3)  To overcome specific engineering problems related to the site or its proposed uses.

   (4)  To evaluate new concepts or technologies applicable to onlot disposal.

   (5)  To evaluate the applicability to onlot disposal of established concepts or technologies having successful use in comparable applications in the field of engineering.

   (6)  To demonstrate a design having successful use in other jurisdictions under environmental conditions similar to or more restrictive than those in this Commonwealth.

   (7)  To utilize under varying site conditions an experimental design, either in whole or in part, which has been deemed successful by the Department.

 (b)  A person desiring to install an experimental sewage system or alter a component of an existing system using a method, technology or design determined to be experimental by the Department shall submit complete preliminary design plans and specifications to the sewage enforcement officer and the Department for review and comment prior to submitting an application for a permit. The Department will determine if classification as an experimental system, method, technology or design is appropriate for the submission and provide review comments to the sewage enforcement officer.

 (c)  The following criteria shall be considered in the design of experimental systems:

   (1)  The volume and rate of sewage flow, including reductions attributed to water conservation devices and recycling devices.

   (2)  The chemical and bacteriological characteristics of the flow, including the varying nature, if any, of the contributing sources.

   (3)  The treatment of the sewage flow, including, if appropriate:

     (i)   The type of treatment, that is aerobic, anaerobic, chemical, or other.

     (ii)   The degree and extent of treatment afforded, including the chemical and biological characteristics of the effluent.

     (iii)   The hydraulic design, including flow rates, retention time, settling rates, and sludge and scum storage.

   (4)  The materials of construction including durability and chemical resistance of all system components.

   (5)  The characteristics and limitations of the disposal site, including, if appropriate:

     (i)   The depth, composition and projected effects of any limiting zone identified through extensive onsite evaluation of the soils present.

     (ii)   The determination of the soil permeability through percolation tests, hydraulic conductivity tests or other acceptable testing procedures conducted on the site.

     (iii)   The chemical and bacteriological characteristics of the subsurface or other waters.

     (iv)   The natural and modified slope of the disposal site and contiguous areas, with particular attention to downslope areas.

     (v)   The relationship of the disposal site to existing and proposed drainage patterns, including surface and subsurface flows.

     (vi)   The stability and renovative abilities of controlled fill areas.

   (6)  The design of the absorption area, including:

     (i)   Dimensions.

     (ii)   Method of distribution and hydraulic design considerations of the distribution system.

     (iii)   Rate of application.

     (iv)   Relationship to other sewage disposal systems or features, water supply sources, surface waters, recharge areas, rock outcrops and other site improvements.

     (v)   Determination of hydraulic loading limitations—that is, interface acceptance rate of hydraulic conductivity of receiving soils—in accordance with accepted principles of hydraulic flow.

   (7)  The effect upon the groundwater, including:

     (i)   Fecal coliform.

     (ii)   Chlorides.

     (iii)   Nitrates.

     (iv)   Nutrients.

     (v)   Other degrading material.

   (8)  Other considerations as may be appropriate to comply with the act.

 (d)  Except as provided in subsection (f), experimental designs will be approved for use only when it has been determined that an individual or community sewage disposal system meeting the requirements of this chapter or another successful experimental design, or that sewage services meeting the requirements of the Clean Streams Law and Article II (relating to water resources), may be installed if the experiment is deemed a failure.

 (e)  Except as provided in subsection (f), monitoring, observation, testing or other requirements which are deemed necessary to verify the success of the experiment shall be required.

 (f)  A replacement area, as specified in subsection (d), and monitoring as specified in subsection (e), may not be required where the experimental design is an attempt to solve an existing pollution or public health problem.

 (g)  An application for an experimental system shall include the following:

   (1)  Detailed plans and specifications sufficient to comply with this section.

   (2)  A description of the system, device or process; its capabilities; and scheduled maintenance, if any, which are necessary for continued function.

   (3)  The identity of the person responsible for the design of the system; performance of scheduled maintenance, if required; and responsibility for repair or replacement in event of failure of the system.

 (h)  Each application for an experimental system shall be accompanied by a statement acknowledging the requirement that the sewage enforcement officer be notified of any malfunction or modification of the original system design.

 (i)  Prior to issuing a permit for an experimental sewage system, the sewage enforcement officer shall consider the comments of the Department.


   The provisions of this §  73.71 amended under section 9 of the Pennsylvania Sewage Facilities Act (35 P. S. §  750.9); The Clean Streams Law (35 P. S. § §  691.1—691.1001); and section 1920-A of The Administrative Code of 1929 (71 P. S. §  510-20).


   The provisions of this §  73.71 adopted August 2, 1971, effective August 14, 1971, 1 Pa.B. 1649; amended April 26, 1974, effective May 13, 1974, 4 Pa.B. 817; amended August 30, 1974, effective September 16, 1974, 4 Pa.B. 1805; amended January 21, 1983, effective January 22, 1983, 13 Pa.B. 508; amended November 7, 1997, effective November 8, 1997, 27 Pa.B. 5877. Immediately preceding text appears at serial pages (217339) to (217341).

Notes of Decisions

   For the construction of a sewage disposal system, the provisions of 25 Pa. Code §  73.11(c) (relating to overall requirements) and 25 Pa. Code §  73.71(b)(5) (relating to standard trenches) require at least six feet between the soil surface and the seasonal high water table. Department of Environmental Resources v. Flynn, 344 A.2d 720 (Pa. Cmwlth. 1975).

Cross References

   This section cited in 25 Pa. Code §  73.3 (relating to policy).

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