Clark County, AR's soil, for a septic absorption field

Very limited

89.2% of Clark County, AR's surveyed soil comes back "Very limited" in USDA's own SSURGO data, the county's dominant condition for a septic absorption field. Practically, that rules out a simple gravity system for most of the county - 89.2% of it sits in USDA's most-constrained bucket. Clark County covers 865.971 square miles and counts 20,920 residents.

This is a county figure, not a parcel figure

Nothing about Clark County, AR's SSURGO figure applies to a specific address - it's a county-wide average. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Clark County.

System cost, conventional vs. engineered

Given Clark County's rating, plan for the engineered-system range rather than the conventional one. The engineered-system range, $10,000-$40,000 (mound or aerobic treatment), is the more realistic number to plan around, against $3,000-$8,000 for a conventional system on the rare lot that passes.

Where this sits nationally

Nationally, Clark County, AR is the 1,352-most-constrained of 3,058 rated counties for septic soil. Within Arkansas alone it ranks 46 of 75.

Further reading

How this rating is built, and its real limits · Conventional vs. engineered septic systems