Gilmer County's SSURGO septic rating
Very limited
Gilmer County, WV: USDA's soil survey calls 98.6% of the county "Very limited" for a septic leach field. That reading means a conventional system is a poor bet here - 98.6% of Gilmer County lands in the strictest "very limited" bucket USDA uses. The county spans 338.503 square miles, home to 7,116 people.
What this number does and doesn't tell you
Nothing about Gilmer County, WV's SSURGO figure applies to a specific address - it's a county-wide average. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.
Gilmer County: conventional vs. engineered cost
98.6% of Gilmer 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, Gilmer County, WV ranks 164 most-constrained nationally, and 5 of 55 within West Virginia.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems