S.C. Code Regs. § ch. 61, 61-56, 61-56.400, app 61-56.400.B
(1) Site/Permitting Requirements
(a) Designs for large and community onsite wastewater systems shall be prepared by a Registered Professional Engineer licensed in South Carolina. Further, the Department may require whatever engineering and soils based submittals are deemed necessary to determine the feasibility and acceptability of any site for such a system.
(b) No part of the system, with the exception of solid pipe, may be located within one hundred (100) linear feet of a receptor.
(c) The depth to the zone of saturation (ZOS) shall be at least thirty-six (36) inches below the naturally occurring soil surface and at least six (6) inches below the deepest point of effluent application.
(d) The depth to any restrictive horizon must be greater than twelve (12) inches below the bottom of the proposed wastewater infiltration trenches.
(e) The long-term acceptance rate for system sizing shall be based upon the most hydraulically limiting, naturally occurring soil texture from the ground surface to twelve (12) inches below the bottom of the proposed wastewater infiltration trenches.
(f) There shall be at least fifty (50) percent reserved subsurface wastewater infiltration area repair or replacement area available consisting of soils suitable for a large onsite wastewater system, except where public (community) systems are utilized, in which case there must be at least one hundred (100) percent repair or replacement area.
(g) Large (greater than 1500 gpd) and community onsite wastewater systems incorporating advanced treatment methods, including but not limited to aerobic pre-treatment, lagoons, surface or subsurface drip irrigation, low pressure pipe distribution, and other maintenance intensive methods, shall be required to obtain a Land Application Permit under R.61-9.505.
(h) Efforts to circumvent the requirements of this standard by configuring remote, individually deeded, adjacently located subsurface wastewater infiltration areas in lieu of a community onsite wastewater system shall not be permitted. On a very limited basis, a few of these individual systems may be considered for mass installation where the wastewater infiltration trenches will be adjacent to each other in a defined area, provided that the combined peak wastewater loading is less than fifteen hundred (1500) gpd. In such cases:
(i) Each subsurface wastewater infiltration area plot shall be sized such that there is sufficient area for one hundred (100) percent subsurface wastewater infiltration area replacement.
(ii) Each plot shall be deeded with all appropriate easements as a lot in conjunction with the specific unit that it serves, and required protective offsets, as described in Section 200.6, shall apply to each individual remote subsurface wastewater infiltration area.
(iii) A plan shall be prepared by a Registered Professional Engineer licensed in South Carolina that illustrates the overall plan; specifies the route and identification of effluent sewers and force mains; specifies the entity responsible for perpetual maintenance of the sewer lines and mass subsurface wastewater infiltration area; specifies the configuration and identification of the individual subsurface wastewater infiltration area parcels; and specifies the manner in which ingress and egress will be provided to the individual subsurface wastewater infiltration area parcels.
(iv) When the combined peak wastewater loading of the adjacently located subsurface wastewater infiltration areas from the entire project will exceed fifteen hundred (1500) gpd, the project shall be considered as a public (community) collection and treatment system, and all requirements described in Section 103.1(5) and this standard shall apply.
(2) Installation Requirements
(a) Large (greater than 1500 gpd) and community onsite wastewater systems shall not be constructed in fill material and shall not be placed any closer to receptors than one hundred (100) feet.
(b) Conventional wastewater infiltration trenches installed in the naturally occurring soil and having a width of thirty-six (36) inches shall be utilized.
(c) Wherever possible, designs that favor long wastewater infiltration trenches, convex landscape positions, and rectangular subsurface wastewater infiltration area configurations shall be required.
(d) All tree/brush removal shall be done in a manner that minimizes the disturbance or loss of naturally occurring soil.
(3) Community or Cluster Collection and Treatment Onsite Wastewater Systems
(a) An onsite wastewater system serving more than one (1) piece of deeded property shall be considered as a public (community) collection and treatment system.
(b) A permit activity will not occur that is inconsistent with a plan or plan amendment approved under Section 208(b) of the Clean Water Act, unless the Department finds such variance necessary to protect the public's health, safety, and welfare.
(c) A public entity shall own the system and shall be responsible for the operation, maintenance, and replacement of all components unless otherwise approved by the Department. The Department may consider a request from a private entity or person; however, such proposals must be evaluated on a case-by-case basis. The Department will evaluate the capability of long-term, reliable system operation in its evaluation of a permit request.
(d) If the project is owned by a private entity or person, the Department shall require financial assurances for the operation, maintenance, and replacement of the tank(s) and subsurface wastewater infiltration area system and relevant collection/pumping components.
(e) There shall be an area equivalent to one hundred (100) percent in size of the original primary subsurface wastewater infiltration area held in reserve for system repair or replacement. This area shall have a suitable configuration and shall meet all minimum requirements for large onsite wastewater systems.
(f) The collection sewer and pumping portions of a community onsite wastewater system shall receive a separate Construction Permit under R.61-67.300.
(g) The responsible party(s) on record shall be required to properly operate and maintain in good working order all system(s) parts which are installed pursuant to the permit and to comply with all terms and conditions of the permit. System parts include, but are not limited to, sealed watertight tanks, lid(s), piping, aggregate, pump, and pump components.
S.C. Code Regs. ch. 61, 61-56, 61-56.400, app 61-56.400.B