S.C. Code Regs. § § 61-56.200

Current through Register Vol. 48, No. 10, October 25, 2024

Section 61-56.200 - Minimum Site Conditions for Onsite Wastewater Systems

200.1. Soil texture, depth of soil to restrictive horizons, and depth to the zone of saturation shall meet minimum standards approved by the Department. These characteristics shall be determined using accepted methodologies in the field of soil science.

200.2. Soils exhibiting massive or platy structure, and soils which have been identified as having substantial amounts of expansible layer clay minerals or smectites, are unsuitable for onsite wastewater systems.

200.3. Where the estimated peak sewage flow will not exceed fifteen hundred (1500) gpd, the minimum vertical separation between the deepest point of effluent application and the zone of saturation shall be at least six (6) inches.

200.4. Where the estimated peak sewage flow will exceed fifteen hundred (1500) gpd, the depth to the zone of saturation 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.

200.5. Depth to rock and other restrictive horizons shall be greater than twelve (12) inches below the deepest point of effluent application.

200.6. Setbacks.

(1) The area of the lot or plot of ground where the onsite wastewater system is to be installed shall be of sufficient size so that no part of the system, excluding solid pipes, will be:

(a) Within five (5) linear feet of a building, or under a driveway or parking area;

(b) Within seventy-five (75) linear feet of a private well;

(c) Within one hundred (100) linear feet of a public well;

(d) Within seventy-five (75) linear feet of the delineated critical area line (tidal waters of coastal waters and tidelands critical areas) as determined by the Department's coastal division; or within seventy-five (75) linear feet of the mean high water (within the banks) elevation (nontidal waters, beach/dune systems and beach critical areas) of an impounded or natural body of water, including streams, canals, and retention ponds;

(e) Within ten (10) feet of upslope and twenty-five (25) feet of downslope curtain drains;

(f) Within twenty-five (25) feet of a drainage ditch or stormwater treatment system including any detention ponds (determined by maximum water elevation);

(g) Within fifteen (15) feet of piped drainage ditches;

(h) Within fifteen (15) feet of an inground pool;

(i) Within twenty-five (25) feet upslope of a basement; and within fifteen (15) feet of the sides of a basement, except that if foundation drains are present and the elevation of the foundation drain is at the same elevation or lower than the elevation of the trench bottom for the subsurface wastewater infiltration area or repair area, then a twenty-five (25) foot setback from the sides of a basement applies. These setbacks do not apply to a septic tank/pump chamber location or where trench installations are downslope of a basement;

(j) Within fifteen (15) feet of the top of the slope of embankments or cuts of two (2) feet or more vertical height when any part of the wastewater infiltration trench is to be placed higher in elevation than the invert of the cut or embankment;

(k) Within five (5) feet of a property line.

(2) Greater protective offsets shall be required when utilizing certain system standards contained within this regulation.

(3) Prior to permitting the onsite wastewater system, jurisdictional determination of any affected wetlands may be required. Should any part of the proposed onsite wastewater system be located in wetlands, approval from the appropriate permitting agency(s) (e.g., U.S. Army Corps of Engineers, SCDHEC Ocean and Coastal Resource Management, etc.) shall be received, and proof of such provided to the Department.

200.7. In addition to the minimum space required in Section 200.6, minimum repair area shall be set aside as follows:

(1) Any new site meeting the minimum design criteria for an onsite wastewater system shall have a usable repair or replacement area equivalent to at least fifty (50) percent of the size of the original system. Where community onsite wastewater systems are utilized, there must be at least one hundred (100) percent repair or replacement area.

(2) Usable repair or replacement area shall be demonstrated to include suitable soil conditions, and shall be free of impervious materials, buildings, or other improvements, setbacks, easements, and other encroachments that would prevent system construction. The undisturbed area between the wastewater infiltration trenches shall not be credited towards this requirement.

200.8. Multiple, individually owned remote subsurface wastewater infiltration areas may be considered for mass installation in a defined area where the wastewater infiltration trenches will be adjacently located to each other, provided that the combined peak wastewater loading is less than fifteen hundred (1500) gpd. In such cases, 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. 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. 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/or 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. When the combined peak wastewater loading of the adjacently loading subsurface wastewater infiltration area will exceed fifteen hundred (1500) gpd, the project shall be considered as a public (community) collection and treatment system, and the onsite wastewater system must comply with the requirements in Section 103.1(5).

S.C. Code Regs. § 61-56.200

Amended by State Register Volume 40, Issue No. 05, eff. 5/27/2016; State Register Volume 45, Issue No. 05, eff. 5/28/2021.