Puget Sound Lowlands
Puget Sound Lowlands: Glacial Till and the High Water Table Problem From Bellingham down through Olympia, much of western Washington sits on glacial till — a dense, compacted mix of silt, sand, and cobbles left behind as ice-age glaciers advanced and retreated across the region. It’s one of the most common limiting layers a septic designer encounters in this part of the state, and it behaves nothing like the sand or gravel homeowners might expect from a place this close…