S.C. Code Regs. § § 61-56.201
Current through Register Vol. 48, No. 10, October 25, 2024
Section 61-56.201 - Minimum Requirements for Onsite Wastewater System Primary Treatment201.1. 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.201.2. Grease Traps. (1) Any new food service facilities permitted under R.61-25, Retail Food Establishments, and served by an onsite wastewater system that is permitted after the effective date of this regulation shall be required to have a properly sized grease trap. This requirement may also apply to new facilities not requiring a food service permit under R.61-25. Exception may be granted in cases where a permitted retail food service establishment performs limited food preparation and/or cooking.(2) Any existing food service establishment that does not have a grease trap, but experiences an onsite wastewater malfunction as a result of grease accumulation, shall be required to immediately comply with all portions of Section 201 as if it were a new food service facility.(3) Any food service facility requiring a grease trap shall provide two (2) separate plumbing stub-outs, one serving the food preparation area and the other serving the restrooms. The stub-out from the restrooms shall discharge directly into the main building septic tank. The stub-out from the food preparation area shall discharge directly into the grease trap with the effluent then directed to the main building septic tank. In order to enhance grease separation while the liquids are hot, the grease trap shall be placed as close as possible to the source of wastewater. Garbage grinders shall not be allowed to discharge to such systems.(4) All grease traps must be directly accessible from the surface and must be equipped with an extended outlet sanitary tee terminating six (6) to twelve (12) inches above the tank bottom. The minimum access opening shall be eighteen (18) inches in diameter.(5) All grease traps serving facilities from which the peak sewage flow exceeds fifteen hundred (1500) gpd shall either be dual chambered or individual tanks in series. If dual chambered, both the dividing wall and the second chamber must be equipped with a sanitary tee terminating six (6) to twelve (12) inches above the tank bottom. (6) It shall be the responsibility of the owner/manager to ensure that the grease trap(s) is cleaned by a licensed septage pumper at frequent intervals to prevent the carryover of grease into other parts of the onsite wastewater system.(7) Determination of Minimum Net Liquid Capacity(a) No grease trap used as part of an onsite wastewater system shall have a net liquid capacity of less than one thousand (1000) gallons. Commercial interior-type grease interceptors shall not be utilized in lieu of a properly sized exterior grease trap.(b) Minimum net liquid capacities of grease traps shall be determined as follows: NLC = GPD x LF x RF, where
NLC = Net Liquid Capacity of Grease Trap (gallons)
GPD = Total Maximum Estimated Sewage Flow (gpd)
LF = Loading Factor (the approximate portion of the total maximum daily flow generated in food preparation areas)
0.3 - Schools and Other Institutions
0.4 - Restaurants
0.5 - Retail Food Stores
RF = Minimum Retention and Storage Factor of 2.5 for Onsite Wastewater Systems
201.3. Other Primary Treatment Methods. The Department, at its discretion, may consider other methods of primary treatment requested by a Registered Professional Engineer where conditions are warranted.
S.C. Code Regs. § 61-56.201
Replaced and amended by State Register Volume 45, Issue No. 05, eff. 5/28/2021.