Richland County, SC Septic Rating
Richland County's SSURGO septic rating
Very limited
Richland County, SC's SSURGO dominant class comes back "Very limited", covering 68.9% of the county. That reading means a conventional system is a poor bet here - it's already USDA's strictest "very limited" bucket, not a partial constraint. The county spans 757 square miles, home to 430,651 people.
What this number does and doesn't tell you
Two lots a mile apart in Richland County can carry different soil, even though they share one countywide rating. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.
Richland County: conventional vs. engineered cost
68.9% of Richland County carrying a "Very limited" reading changes the realistic budget here. Conventional systems run $3,000-$8,000 where they pass; where they don't, engineered alternatives (mound or aerobic treatment, whichever the health department requires) run $10,000-$40,000 - budget toward the higher figure until a perc test says otherwise.
Where this sits nationally
Among the 3,058 rated counties on this site, Richland County, SC ranks 2,499 most-constrained nationally, and 25 of 46 within South Carolina.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems