Oakland County, MI's soil, for a septic absorption field

Very limited

In Oakland County, MI, 73.5% of the surveyed land carries a "Very limited" rating for a standard septic drain field. That reading means a conventional system is a poor bet here - 73.5% of Oakland County lands in the strictest "very limited" bucket USDA uses. Oakland County covers 867.426 square miles and counts 1,296,888 residents.

This is a county figure, not a parcel figure

Nothing about Oakland County, MI's SSURGO figure applies to a specific address - it's a county-wide average. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Oakland County.

System cost, conventional vs. engineered

Given Oakland County's rating, plan for the engineered-system range rather than the conventional one. 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.

How Oakland County, MI compares

Nationally, Oakland County, MI is the 2,346-most-constrained of 3,058 rated counties for septic soil. Within Michigan alone it ranks 81 of 83.

Further reading

How this rating is built, and its real limits · Conventional vs. engineered septic systems