South Carolina Code of Regulations › Chapter 61 - DEPARTMENT OF HEALTH AND ENVIRONMENTAL CONTROL › Subchapter 61-56 - ONSITE WASTEWATER SYSTEMS › Section 61-56.201 - Minimum Requirements for Onsite Wastewater System Primary Treatment

Current through Register Vol. 48, No. 6, June 28, 2024
201.1. Septic
			 Tanks.
(1) All persons or firms manufacturing
			 septic tanks for use in South Carolina shall submit detailed plans for each
			 size tank to the Department and shall receive written approval for such tanks
			 prior to their installation in the state.
(2) The design and construction of each
			 septic tank shall be in accordance with minimum standards contained within this
			 regulation.
(3) No septic tank
			 shall be installed which has a net liquid capacity of less than one thousand
			 (1000) gallons. Such tanks shall be sufficient to serve dwellings of four (4)
			 bedrooms or less. Two hundred fifty (250) gallons additional capacity shall be
			 required for each bedroom over four (4).
(4) When multiple dwellings share a common
			 onsite wastewater system, each dwelling unit shall either have its own properly
			 sized septic tank or it must discharge to a larger tank(s) that provides the
			 combined total of the minimum septic tank capacities required for each
			 contributing unit. Exception may be granted when a public entity, or private
			 entity with financial assurances, is approved by the Department to provide
			 operation and maintenance of the system. In such cases, the formula in Section
			 201.1(5) may be considered.
(5)
			 Septic tanks serving establishments other than individual dwellings shall be
			 sized according to actual peak flow data, when available, or by estimates of
			 peak sewage flow, as set forth in standards established by the Department. For
			 those septic tanks receiving peak flows less than fifteen hundred (1500) gpd,
			 the net liquid capacity shall be calculated by multiplying 1.5 times the peak
			 flow expressed in (gpd). For those septic tanks receiving peak flows between
			 fifteen hundred (1500) and forty-five hundred (4500) gpd, the net liquid
			 capacity shall be calculated as follows:
Volume (V) = 1125 gal. plus (0.75 x Peak Flow(gpd)).
For those septic tanks receiving peak flows in excess of
				forty-five hundred (4500) gpd, the net liquid capacity shall be at least equal
				to the peak flow:
Volume (V) = Peak Flow (gpd)
(6) The minimum liquid capacity requirements
			 shall be met by the use of a single septic tank or two (2) or more tanks
			 installed in series. Septic tanks joined in series shall be interconnected by
			 an upper effluent pipe(s) with a minimum diameter of four (4) inches and a
			 lower sludge pipe(s) with a minimum diameter of twelve (12) inches. The upper
			 connection(s) shall be installed level from tank to tank, and the lower sludge
			 pipe connection(s) shall be installed level and shall be placed twelve (12)
			 inches above the bottoms of the tanks. The lower sludge pipe connection(s) can
			 be eliminated if the first tank in series contains at least two-thirds (2/3) of
			 the total required liquid capacity. There shall be no more than two (2) inches
			 of fall from the inlet invert of the first tank to the outlet invert of the
			 last tank in series.