Septic suitability in Marion County, WV
Very limited
Marion County, WV's SSURGO dominant class comes back "Very limited", covering 93.2% of the county. Practically, that rules out a simple gravity system for most of the county - 93.2% of it sits in USDA's most-constrained bucket. For scale: 308.785 square miles and 55,649 people call Marion County home.
Before you rely on this for one lot
Nothing about Marion County, WV's SSURGO figure applies to a specific address - it's a county-wide average. The real answer for one lot is still a site-specific perc test, running about $750-$1,850 (typically near $1,300).
Budgeting for a system in Marion County, WV
Marion County's soil reading pushes the likely outcome toward an engineered system rather than a conventional one. 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, Marion County, WV ranks 901 most-constrained nationally, and 41 of 55 within West Virginia.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems