Septic soil in Halifax County, NC, by the numbers
Very limited
72.9% of Halifax County, NC's surveyed soil comes back "Very limited" in USDA's own SSURGO data, the county's dominant condition for a septic absorption field. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 72.9% of Halifax County's land. Halifax County, NC is 723.738 square miles with a population of 46,992.
What Halifax County's reading doesn't cover
Halifax County's rating is an average across the whole county, not a promise about any one lot inside it. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Halifax County will actually do.
What a system would cost here
With 72.9% of Halifax County rating "Very limited", a standard gravity system is not a safe assumption here. 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.
Halifax County's rank among North Carolina counties
Nationally, Halifax County, NC is the 2,375-most-constrained of 3,058 rated counties for septic soil. Within North Carolina alone it ranks 48 of 97.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems