Grading, Topsoil & Seedbed Prep in Portland, OR

Grading, topsoil and seedbed prep decide whether a Portland lawn drains, roots and stays level, long before any seed goes down. We handle the dirt work between rough construction grading and a finished lawn: yard grading to move water away from the house, land grading on larger lots, topsoil delivery and spreading, loosening compacted ground and the final fine grade that hydroseeding needs. When reshaping the surface will not dry out a soggy yard, the same crew digs and trenches for drainage lines too.

Reading the soil first

Portland soils vary from block to block. On the Columbia terraces, Latourell loam is a well drained, dark brown loam with moderate permeability. Nearby Powell soils are somewhat poorly drained and have a fragipan, a dense layer that slows water moving down. OSU Extension describes typical Willamette Valley lawn soil as silty clay or clay loam. Each of those calls for different prep, so we dig test holes on the site visit before deciding whether you need topsoil, loosening, drainage or just a good rake.

Construction leftovers

New homes often end up with subsoil and excavation spoils on top and the original topsoil long gone. OSU's advice is plain: either test it or bring in new soil. When we import soil, we try to match the existing texture so water and roots move between layers. If a sandy soil goes on, it goes on as a layer at least 6 inches deep after compaction, not tilled into clay; OSU research shows mixing sand into clay makes compaction worse until the mix is around 80 percent sand.

Slope and drainage

The basic grade should carry water away from the foundation and toward a swale, street or drain, without low spots where water stands through the winter. On flat east side lots that may mean only a gentle fall across the yard. On hillside lots it can mean shaping a swale at the toe of a slope or cutting a bench. Where a perched water table or poorly drained subsoil keeps a yard wet, a trench drain can do more than any amount of regrading.

Topsoil, not just dirt

Purchased topsoil can be anything from real topsoil to river silt or clean fill. We tell you what we are bringing, how deep it will go and roughly how many cubic yards the job needs before it is ordered. Organic matter can help in the short term, but OSU cautions that adding more than about 15 percent by volume can lead to settling and a bumpy lawn as it breaks down, so we use compost in moderation.

Fine grading for hydroseed

The final pass is what you will see in the finished lawn. We rake or drag the surface smooth, remove rocks and roots, and leave it lightly firm so footprints are shallow. A good fine grade also sits just below walks and driveways so mowers do not scalp the edges.

Working around the weather

Clay and silt loam soils smear and compact when worked wet. In Portland's rainy months we schedule grading for drier spells, and when that is not possible, we cover finished grade quickly so rain does not erode it. On permitted sites, Title 10 deadlines for stabilizing disturbed ground apply as soon as the dirt moves.

Pricing

Grading and topsoil work is priced by area, volume and access. The table lists published ranges for leveling, fine grading and topsoil. Your bill matches the quote you sign. Get a free estimate