Paver Installation in Bonney Lake, WA

Bonney Lake sits on a plateau above the White River and Puyallup valleys, with Lake Tapps on its north side. Most neighborhoods are on rolling ground, but the edges of the plateau drop off steeply, and many newer subdivisions were graded into terraces. That makes retaining walls a bigger part of the work here than in flatter towns.

The crews who build Bonney Lake walls are ND employees, backed by 19 years in the trade, more than 425 projects, and a 4.7 Google rating. They work out of our Yelm office and cover the plateau as part of our regular Pierce County route.

On a grid of points across Bonney Lake in USDA soil survey data, the most common soil was Alderwood gravelly sandy loam on 8 to 15 and 15 to 30 percent slopes. USDA's description of the Alderwood series puts a dense layer of glacial till 50 to 100 centimeters down, roughly 20 to 40 inches, with a perched water table 30 to 90 centimeters below the surface between December and April. Rain soaks into the upper soil, stops at the till, and moves sideways downhill.

On a sloped or terraced lot, that sideways water ends up behind retaining walls and under the low side of patios. It is the main reason walls bulge and patios sink along the downhill edge. Every wall we build here gets drain rock and a pipe behind it, routed to a legal outlet.

The survey also maps Everett very gravelly sandy loam on some slopes, which drains fast, and Kapowsin gravelly ashy loam, which has a cemented layer 20 to 40 inches down and a perched water table that can rise to 11 to 24 inches below the surface from December through June. The steep escarpments down to the valley are mapped on 45 to 70 percent slopes. Building near those edges takes more care and, often, an engineer.

Bonney Lake's Retaining Wall Submittal Checklist sets a clear line. If a project proposes walls taller than 4 feet, or walls supporting any adjacent surcharge load such as terraced walls, buildings, roadways, or driveways, the city requires a Structural Retaining Wall Design Report from a Professional Civil Engineer licensed in Washington.

That report must include stamped wall plans, stamped structural calculations, and a geotechnical report stamped by a licensed geotechnical engineer. Note that terraced walls are named as a surcharge. Two 3-foot walls stacked close together on a hillside can land in the engineered category even though neither is over 4 feet.

For homeowners, the takeaway is to plan the wall layout early. Spacing tiers apart, pulling a driveway back from the top of a wall, or reshaping the grade can sometimes keep a project in a simpler path. When the site needs an engineered wall, we plan for the engineer and permit time from the start.

Most Bonney Lake wall problems start in the planning, not the building. Settle these points before design is final.

NOAA's 1991-2020 normals show 48.31 inches of precipitation a year at the Buckley station to the east and 45.13 inches at McMillin Reservoir to the southwest, with about 16 inches December through February at both. Both also record a few inches of snow in a normal year: 4.3 at Buckley and 5.6 at McMillin. On Alderwood till that water stays near the surface for months, so we plan base drainage for a wet winter.

Large lots make the state's stormwater thresholds easier to hit. Ecology's manual for western Washington counts new and replaced hard surface together: at 2,000 square feet of it, or 7,000 square feet of disturbed ground, minimum requirements 1 through 5 apply. A long driveway replacement plus a backyard patio on a large Bonney Lake lot can reach that. We total the areas early and confirm the city's current rules for the address.

Typical requests on the plateau and around Lake Tapps:

Bonney Lake visits run longer than most, because we measure the whole grade change, not just the patio footprint, and we look for anything that would add surcharge above a wall. The free 3D design shows wall tiers, setbacks, and patio levels together. The free quote separates wall work, base and paving, drainage, and engineering or permit costs, so you can see which choices change the price. The same ND crew builds the walls and the paving.