S.C. Code Regs. § § 61-56.202

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

Section 61-56.202 - Minimum Requirements for Onsite Wastewater System Final Treatment and Disposal Systems

(1) All pipe utilized in onsite wastewater systems shall meet applicable ASTM standards. All piping utilized in the connection of a septic tank to a subsurface wastewater infiltration area, including that which is utilized in the connection of adjacent wastewater infiltration trenches, whether they be level or serially fed, shall be non-perforated Schedule 40 PVC pipe. Such pipe, excluding force mains, shall be a minimum of three (3) inches in diameter. The connecting pipe shall not be surrounded by aggregate.

(2) At least seven (7) feet of undisturbed earth shall exist between wastewater infiltration trenches.

(3) The aggregate used in onsite wastewater systems shall be a material approved by the Department and shall range in size from one-half (1/2) inch to two and one-half (2 1/2) inches. Fines shall be prohibited. Tire chips shall range in size from one-half (1/2) inch to four (4) inches in size, and wire strands shall not protrude more than one-half (1/2) inch from the sides.

(4) Drop boxes shall be utilized when deemed necessary by the Department. When required, they shall be surrounded and stabilized by at least two (2) feet of undisturbed or manually compacted earth, and the wastewater infiltration trenches shall be fed with non-perforated Schedule 40 PVC pipe. The invert of the drop box overflow pipe shall be at the same elevation as the top of the aggregate in the trenches fed by that box, and the top of the aggregate shall be level throughout the trench run. Other methods that affect serial distribution shall also overflow at the same elevation as the top of the aggregate.

(5) There shall be at least two (2) feet of earthen buffer between the septic tank and all portions of adjacent wastewater infiltration trenches. Where gravity flow is utilized, the invert elevation of the septic tank outlet shall be at the same elevation or higher than the top of the aggregate in the highest placed wastewater infiltration trench.

(6) To ensure proper operation and protection of onsite wastewater systems, the Department may require individual or combined installation of drainage swales, curtain or interceptor drains, protective barriers, or protective ground cover. Final approval of the permit may be withheld until such time as these improvements are completed.

(7) The bottom of each wastewater infiltration trench, including the distribution pipe contained within, shall be as level as possible, with an elevation differential not to exceed two (2) inches throughout the trench run.

(8) The required number, length, and configuration of wastewater infiltration trenches shall be determined by the Department and shall be based upon the Standard for Determining Peak Sewage Flow Rates (Section 501, Peak Sewage Flow Rate Standard) from Commercial and Recreational Establishments in conjunction with the Long-Term Acceptance Rate Standard for Onsite Wastewater Systems (Section 500, Long-Term Acceptance Rate Standard for Onsite Wastewater Systems). All systems shall be sized 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.

(9) The aggregate over the distribution pipe shall be covered with a strong, untreated pervious material to prevent infiltration of backfill material.

S.C. Code Regs. § 61-56.202

Replaced and amended by State Register Volume 45, Issue No. 05, eff. 5/28/2021.