S.C. Code Regs. § § 61-56.500

Current through Register Vol. 48, No. 11, November 22, 2024

Section 61-56.500 - Long-Term Acceptance Rate Standard for Onsite Wastewater Systems

USDA-NRCS SOIL TEXTURE	SOIL CHARACTERISTICS WHEN MOIST (FIELD TEST)	LONG-TERM ACCEPTANCE RATE (GPD/SF)
Sand (S)	Sand has a gritty feel, does not stain the fingers, and does not form ribbon or ball when wet or moist.	0.9 - 1.0	Class I
Loamy Sand (LS)	Loamy sand has a gritty feel, stains the fingers, forms a weak ball, and cannot be handled without breaking.
Sandy Loam (SL)	Sandy loam has a gritty feel and forms a ball that can be picked up with the fingers and handled with care without breaking.	0.7 - 0.8	Class II
Loam (L)	Loam may have a slightly gritty feel but does not show a fingerprint, and forms only short ribbons from 0.25 - 0.50 inch. Loam will form a ball that can be handled without breaking.
Sandy Clay Loam (SCL)	Sandy clay loam has a gritty feel but contains enough clay to form a firm ball and may ribbon from 0.75 - 1.0 inch.	0.5 - 0.6	Class III
Clay Loam (CL)	Clay loam is sticky when moist, forms a ribbon of 1.0 - 2.0 inches, and produces a slight sheen when rubbed with the thumbnail. Clay loam produces a nondistinct fingerprint.
Silt Loam (SiL)	Silt loam has a floury feel when moist and will show a fingerprint, but will not ribbon and forms only a weak ball.
Silt (Si)	Silt has a floury feel when moist and is sticky when wet but will not ribbon and forms a ball that will tolerate some handling.	0.1 - 0.4	Class IV
Silty Clay Loam (SiCL)	Silty clay loam has a slight floury feel, is sticky when moist, and will ribbon from 1.0 - 2.0 inches. Rubbing with thumbnail produces a moderate sheen. Silty clay loam produces a distinct fingerprint.
Sandy Clay (SC)	Sandy clay is plastic, gritty, and sticky when moist, forms a firm ball, and produces a ribbon in excess of 2.0 inches.
Clay ( C)	Clay is both sticky and plastic when moist, produces a ribbon in excess of 2.0 inches, produces a high sheen when rubbed with the thumbnail, and forms a strong ball resistant to breaking.
Silty Clay (SiC)	Silty clay has a slight floury feel, is both sticky and plastic when moist, forms a ball, and produces a ribbon in excess of 2.0 inches.

(1) 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. Alternative and experimental systems installed beneath expansive soils shall be sized at a long-term acceptance rate not to exceed 0.2-0.25 gpd/sf as specified in approved standards.

(2) Soil texture shall be estimated by field testing as described above. Laboratory determination of soil texture may be substituted for field testing when conducted in accordance with: (1) Bouyoucos, G.J. 1962. Hydrometer Method Improved for Making Particle Size Analyses of Soils. Agron. J. 53:464-465; (2) ASTM D-422, Procedures for Sieve and Hydrometer Analyses; or (3) the Pipette Method (ASA-CSSA-SSSA), USDA Methods of Soils Analysis, Soil Survey Laboratory Information Manual, and Soil Survey Laboratory Methods Manual.

(3) The total linear feet (lf) for conventional onsite wastewater systems shall be calculated by dividing the peak daily flow (gpd) by the long-term acceptance rate (gpd/sf) and dividing the result by the trench width (ft): lf = gpd ÷ gpd/sf ÷ ft. The total linear feet for alternative systems may either be increased or decreased in accordance with factors specified in alternative standards.

S.C. Code Regs. § 61-56.500

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