Septic suitability in Union County, NJ
Very limited
Union County, NJ's SSURGO dominant class comes back "Very limited", covering 59.3% of the county. Practically, that rules out a simple gravity system for most of the county - 59.3% of it sits in USDA's most-constrained bucket. The county spans 102.767 square miles, home to 594,160 people.
What this number does and doesn't tell you
USDA's survey covers the whole of Union County, NJ 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.
Union County: conventional vs. engineered cost
59.3% of Union 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, Union County, NJ ranks 2,731 most-constrained nationally, and 21 of 21 within New Jersey.
Before you act on this
How this rating is built, and its real limits · Conventional vs. engineered septic systems