South King County
Landscaping & Hardscaping in Covington, WA
Quick answer
Covington sits on a glacial till plateau around 400 feet, so hardpan and standing winter water drive nearly every project here. We build drainage-first paver patios, retaining walls, fences and sprinkler systems, about twelve minutes out Kent-Kangley Road from our Kent shop. Backflow assemblies are required by Covington Water District.
- From our Kent shop
- about 12 minutes
- ZIP codes served
- 98042
- Licensed in WA
- Bonded & insured
Covington only became a city in 1997, but the neighborhoods are older than that. Most of what we work on was platted while this was still unincorporated King County, through the 1980s and into the 90s: generous lots by South King County standards, wide streets, cul-de-sacs, and back yards big enough that homeowners here genuinely use them. Timberlane is the classic example. Big flat parcels, mature Douglas fir and western red cedar left standing between houses, and thirty-year-old landscaping that has reached the end of its life all at once.
The plateau is around 400 to 500 feet of elevation, which is high enough to change the weather. Covington runs measurably wetter than the Green River valley a few miles west, sitting at the front edge of the Cascade foothill gradient that keeps climbing toward Maple Valley and Black Diamond. More rain landing on ground that does not accept it is the whole story of landscaping here.
Because underneath is till. Dig anywhere in Covington and you go through a foot or two of soil, then hit a cemented hardpan that a shovel rings off. Water does not infiltrate through it. It perches on top and moves sideways, which is why the standard Covington complaint sounds identical from house to house: the back lawn is a sponge from November to March, the dog tracks mud through the kitchen, the swing set sits in a puddle, and a French drain someone installed in 2014 did nothing because it discharged into ground just as saturated as the ground it drained. The gravel operations along Kent-Kangley and SR 18 are working the outwash sand and gravel that sits in bands through this same landscape, which is a reminder that what is under any given Covington lot can shift from free-draining gravel to concrete-hard till within one property line.
So we design drainage first and the pretty part second. A Covington patio gets its base built with a route for the perched water rather than a dam across the slope, and the finish grade is set with fall to a real outlet. Catch basins go where water already collects, not where they look tidy on a plan. Fence posts frequently need an auger with real torque or a hand-jack through the hardpan, and a post hole that fills with water overnight gets drain rock in the bottom instead of a bag of dry mix dumped in a puddle. Sod that goes down over unamended till will fail its first winter, so subgrade prep and compost tilled into the top layer is not an upsell, it is the reason the lawn survives.
For planting we lean on what actually thrives on this plateau. Sword fern, salal and evergreen huckleberry under the conifers the builder left. Kinnikinnick and hebe on the gravelly, sunnier sections. Red twig dogwood and carex in the low corner that will never be truly dry. Vine maple and rhododendron where a yard needs some height. We draw the plan in-house and our own crew does the excavation and the hardscape, so what shows up on site matches the drawing, and Covington is twelve minutes from the shop, which makes a spring irrigation start-up or a fall blowout a routine stop rather than a special trip.
Ground conditions in Covington
Covington sits on the glacial till plateau east of the Green River valley at roughly 400 to 500 feet. The dominant soil is Alderwood gravelly sandy loam over dense, nearly impermeable Vashon till, with hardpan commonly encountered between 12 and 30 inches. Some parts of the city are on recessional outwash instead, coarse sand and gravel that drains freely, and the boundary between the two can run straight through a single lot. The practical result is perched groundwater: winter rain saturates the shallow soil, then travels laterally on top of the hardpan until something intercepts it. Annual rainfall here is meaningfully higher than in Kent or Auburn because Covington sits at the start of the foothill gradient. Jenkins Creek, Little Soos Creek and Big Soos Creek drain the area, and wetlands are common in the low ground between plats.
Permits
The City of Covington handles its own permitting from City Hall on SE 271st Street and uses a surface water design manual based on the King County standard. Retaining walls over 4 feet from the bottom of the footing to the top require a permit and stamped engineering, and tiered walls or walls carrying a surcharge can be reviewed together as a single taller structure rather than as separate short ones. Because Covington drains to Jenkins Creek and the Soos Creek system, stream and wetland buffers are a live issue on a surprising number of lots, and buffers on fish-bearing streams here are wide. Clearing and grading volume, and adding new plus replaced impervious surface past the drainage review threshold, each trigger their own review, which can catch a large patio or a paver driveway even when no wall is involved. Standard residential fences within height limits generally do not need a permit. Covington updates its adopted manuals periodically, so we verify current thresholds with the city at permit time.
Neighborhoods we work in
- Timberlane
- Jenkins Creek
- Pipe Lake
- Lake Lucerne
- Soos Creek
- Covington Town Center
- Kentwood area
Services we offer in Covington
Most requested in Covington
Covington: common questions
Why does my Covington yard hold water every winter?
Hardpan. The glacial till under most of the city is close to impermeable, so once the shallow soil above it saturates, everything that falls afterward perches on that layer and runs sideways until it reaches a low spot. Adding topsoil or aerating does not solve it. Water needs a graded collection point and a solid line to somewhere it can legally discharge.
What does yard drainage typically cost around here?
A residential catch basin network with a solid tightline running to a legal outlet generally falls in the range of roughly $2,500 to $7,500 installed in the Puget Sound market, driven mostly by run length, depth through hardpan, and how far the discharge point is. That is a typical market range for planning purposes, not a quote. A site walkthrough is what turns it into a real number.
Do I need a permit for a retaining wall in Covington?
Over 4 feet from the bottom of the footing to the top, yes, with stamped engineering. Under that with no surcharge, usually not. Two things catch people out here: tiered walls can be evaluated as one taller wall, and a lot backing onto Jenkins Creek or Soos Creek may have a stream buffer that restricts where you can build at all. We check both before pricing.
Who handles backflow testing on a Covington sprinkler system?
Covington Water District serves most of the city and requires an approved backflow assembly on an irrigation connection, with an annual test by a certified tester and results reported to the district. We install the assembly to district requirements, get the initial test done, and hand you the paperwork so the annual notice does not catch you off guard.
Can you set fence posts in Covington hardpan?
Yes, though it is slower than a valley job and we price it that way. Till this dense usually needs a rock auger or hand work to reach depth, and a hole that fills overnight gets drain rock at the bottom so the post base is not standing in water for four months a year. Skipping that is why so many thirty-year-old Covington fences rot at the ground line first.