(a) Official plans and official plan
revisions proposing individual and community onlot sewage systems shall
evaluate general site suitability to establish their use as a feasible
alternative, as specified in subsection (b).
(b) When an official plan or revision
proposes the renovation of sewage effluent by means of a subsurface absorption
area or a spray irrigation system, the following shall be provided:
(1) Anticipated raw waste characteristics of
the sewage. Where industrial wastes as defined in the Clean Streams Law are
expected to be present in the raw sewage, §
72.25(g)(2)
(relating to issuance of permits) applies.
(2) Documentation that the soils and geology
of the proposed site are generally suitable for the installation of the systems
including:
(i) Soils mapping as per the
United States Soil Conservation Service mapping or the equivalent.
(ii) Contour lines as per the United States
Geologic Survey Topographic mapping or site determined contour lines.
(iii) Soil profiles as described in Chapter
73 (relating to standards for onlot sewage treatment facilities) shall be
performed to insure that an adequate area with suitable soils is available in
the area of the proposed system. These profiles shall be approximately equally
distributed among the various soils mapped in the area. For the purpose of this
section, each change of slope or change in erosion characteristic specified as
part of the soil classification system of the United States Department of
Agriculture, Natural Resources Conservation Service will be equivalent to a
change in soil type.
(iv) A
sufficient number of percolation tests to confirm that the general percolation
rate for each soil type in the area where systems are to be installed is within
acceptable limits as described in Chapter 73. For the purpose of this section,
each change of slope or change in erosion characteristic specified as part of
the soil classification system of the United States Soil Conservation Service
will be equivalent to a change in soil type.
(c) This chapter does not preclude the use of
individual and community onlot sewage systems using subsurface soil absorption
areas on lots less than 1 acre in size or the use of large volume onlot sewage
systems. Because of the potential for the creation of a public health hazard or
pollution of the waters of this Commonwealth from high density use, improper
system siting or inadequate maintenance of individual and community onlot
systems, particular attention shall be given in official plans and revisions to
the technical and institutional feasibility of using the systems.
(1) Additional permeability testing is
required when an official plan or revision proposes the use of a large volume
onlot sewage system or a community onlot system with a sewage flow in excess of
10,000 gpd, and may be required for other onlot system proposals where the
total absorption area is greater than 5,000 square feet or where soil profiles
or geology reveal slowly permeable conditions below the depth at which the
percolation test was performed. Sufficient testing shall be conducted to:
(i) Determine the permeability of an
identified restrictive soil, geologic or hydraulic layer.
(ii) Determine the vertical rate and the
horizontal rate of flow in or above the restrictive layers in inches per
hour.
(iii) Determine the
application rate required as derived from the information contained in
subparagraphs (i) and (ii). When this application rate is more stringent than
that derived from percolation testing, as contained in Chapter 73, the more
stringent rate shall be used to size the system.
(iv) Determine the impact of the system on
groundwater mounding.
(2)
A preliminary hydrogeologic evaluation is required when the use of subsurface
soil absorption areas is proposed and one of the following exists:
(i) A large volume onlot sewage system will
be used.
(ii) A subdivision of more
than 50 equivalent dwelling units with a density of more than one equivalent
dwelling unit per acre is proposed.
(iii) The Department has documented that the
quality of water supplies within 1/4 mile of the proposed site exceed five
parts per million (ppm) nitrate-nitrogen.
(iv) The Department has determined that known
geological conditions for the proposed site may contribute to the potential for
groundwater pollution from the systems.
(3) A preliminary hydrogeologic evaluation
shall include as a minimum, in map and narrative report form:
(i) The topographic location of the proposed
systems in relation to groundwater or surface water flow, or both.
(ii) Estimated wastewater dispersion plume
using an average daily flow of 262.5 gallons per equivalent dwelling unit per
day or other flow supported by documentation.
(iii) Identification and location of existing
and potential groundwater uses in the estimated area of impacted
groundwater.
(4) Detailed
hydrogeologic studies may be required by the Department when the preliminary
hydrogeologic evaluation identifies a potential for a conflict between the
proposal and existing or potential future uses of groundwater in the area.
Detailed hydrogeologic studies shall identify constituents of the sewage which
may pollute groundwater and shall evaluate methods for preventing the pollution
of the waters of this Commonwealth. A detailed hydrogeologic study shall be
submitted using the Department's sewage facilities planning
module.
(d)
Municipalities shall evaluate and implement options for establishing an
institutional framework to assure the proper operation and maintenance of these
systems under the act and this part.