Permeable Pavers in Lakewood, WA — Infiltration Tested Against Lakewood's Three Soils.

A permeable interlocking concrete pavement system moves water through the joints into an open-graded reservoir base and, ideally, into the native soil below. That last step is the one that is not automatic. If the native soil will not take the water, the system is a very expensive puddle. Lakewood is three soils in one city: glacial till near American Lake, sandy loam through the Steilacoom corridor, and heavier clay out toward Fort Steilacoom. The boundary between them can fall inside a single lot.

Which soil is under your yard decides the base depth, the gravel spec, and whether you need drainage at all. Guessing from the neighbor's job is how installers get this city wrong. So we test infiltration before we design, and the design follows the answer. Where the soil accepts water, the reservoir infiltrates directly. Where it will not — which is common on the tighter ground in and around Lakewood — the reservoir is sized to store the design storm and release it through a perforated underdrain, so the system still performs and still counts. That distinction also drives whether the project earns impervious-surface credit under Pierce County stormwater rules, which is the reason most American Lake homeowners come to us about permeable in the first place. Designed correctly, it also neutralizes a base engineered for the wrong one of three soils.