Septic companies in Olympia, WA

What the ground in Olympia is like

The USDA soil survey rates mapped ground in Olympia for septic drain-field suitability across roughly 18 square miles. About 98% of the rated ground is classed "Very limited", meaning the soil has one or more features unfavorable for a conventional drain field, and the limits generally cannot be overcome without major soil reclamation, special design or expensive installation.

In Olympia, the leading limit is depth to the saturated zone: the water table sits so close to the surface that a drain field has little dry soil left underneath it. Effluent needs unsaturated ground to treat and disperse; when that column is thin, the field has nowhere safe to go. The survey flags that limit on about 85% of the rated ground here.

The limiting features the survey records most often here:

• Depth to saturated zone84.8%
• Slope56.3%
• Seepage, bottom layer43.0%
• Slow water movement18.9%

This is survey data for mapped areas, not a substitute for a site evaluation on your own lot. Conditions on a single parcel can differ from the map.

USDA NRCS SSURGO, ENG Septic Tank Absorption Fields · 98% Very limited · Depth to saturated zone · 41 map units · 18.22 sq mi · read 2026-08-30