Septic suitability in Roanoke city, VA
Very limited
USDA puts Roanoke city, VA at "Very limited" for septic absorption fields, the dominant reading across 76.2% of the county's soil. Expect the ground itself to work against a plain gravity system; USDA's strictest bucket alone covers 76.2% of the county. The county spans 42.521 square miles, home to 97,912 people.
What this number does and doesn't tell you
USDA's survey covers the whole of Roanoke city, VA at once, not any single address. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.
Roanoke city: conventional vs. engineered cost
76.2% of Roanoke city 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.
Roanoke city's rank among Virginia counties
Among the 3,058 rated counties on this site, Roanoke city, VA ranks 2,221 most-constrained nationally, and 53 of 110 within Virginia.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems