South Carolina Code of Regulations › Chapter 61 - DEPARTMENT OF HEALTH AND ENVIRONMENTAL CONTROL › Subchapter 61-56 - ONSITE WASTEWATER SYSTEMS › Section 61-56.400 - Appendices of Standards for Permitted Systems › Appendix 61-56.400.L - System Standard 370/371 - Shallow Placement with Fill Cap for Sites with Shallow Class IV Soil

Current through Register Vol. 48, No. 6, June 28, 2024
(1) Site/Permitting Requirements
(a) There must not be a zone of saturation (ZOS) within
				  twelve (12) inches of the naturally occurring soil surface.
(b) The depth to any restrictive horizon must be greater than
				  twelve (12) inches below the bottom of the proposed wastewater infiltration
				  trenches.
(c) No part of this system can be installed within one
				  hundred twenty-five (125) feet of the ordinary high water elevation within the
				  banks of environmentally sensitive waters.
(d) This system may be considered for installation on
				  contiguous lots in new subdivisions approved after the effective date of this
				  standard provided a setback of at least seventy-five (75) feet is maintained
				  between the system and all adjacent property lines. The seventy-five (75) foot
				  setback shall be measured from the point at which the fill cap taper intersects
				  with the naturally occurring soil surface.
(e) This system cannot be considered for facilities with peak
				  sewage flow rates in excess of four hundred eighty (480) gpd. In addition, this
				  system shall not be considered for facilities requiring grease traps.
(f) There shall be a replacement area equivalent to at least
				  fifty (50) percent in size of the original system area held in reserve for
				  system repair. This area shall have a suitable configuration and shall meet the
				  minimum soil and site conditions of this regulation.
(g) 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.
(2) Installation Requirements
(a) Effluent discharged to this system must receive a higher
				  degree of treatment than that provided by a conventional septic tank (e.g. two
				  (2) compartment septic tank or two (2) septic tanks in series).
(b) Where gravity flow from the septic tank to the subsurface
				  wastewater infiltration area is utilized, the invert elevation of the septic
				  tank outlet shall be installed at an elevation at least equal to or higher than
				  the top of the aggregate in the highest wastewater infiltration
				  trench(es).
(c) The required fill cap must extend at least five (5) feet
				  beyond the limits of the wastewater infiltration trenches, and it must taper to
				  the original soil surface at a slope not to exceed ten (10) percent . The
				  required seventy-five (75) foot property line setback shall be measured from
				  the point at which the fill cap taper intersects with the naturally occurring
				  soil surface.
(d) The required fill material must be soil texture Class I,
				  Class II, or Class III and be void of extraneous debris such as organic matter,
				  building materials, etc.
(e) The depth of the fill cap shall provide a minimum of
				  twelve (12) inches backfill above the top of the wastewater infiltration trench
				  aggregate.
(f) The wastewater infiltration trench width shall be
				  thirty-six (36) inches
.
(g) All tree and brush removal shall be done in a manner that
				  minimizes the disturbance or loss of naturally occurring soil.
(3) Final Landscaping and Drainage
(a) The septic tank and fill cap area shall be backfilled and
				  shaped to promote the runoff of surface water.
(b) Where natural surface drainage does not exist, a swale
				  shall be constructed adjacent to the filled area to divert surface water away
				  from the onsite wastewater system to a positive outfall. The installation of
				  ditches, curtain drains, and rain gutters may be required to intercept and
				  divert water away from the onsite wastewater system location.
(c) A barrier to preclude parking and vehicular traffic over
				  the system area may be required.
(d) Following final landscaping, seeding or sodding may be
				  required to prevent erosion.
(e) Final approval shall be withheld until all landscaping
				  and drainage improvements have been satisfactorily completed.
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