Gravel, Stone and Garden Soil Delivery in Washington, DC

Narrow lots and rear yards

The Census counts 26,928 housing units in ZIP 20001, the largest figure in this part of the city. Just 4 percent of those homes are detached single-family houses, and the median one dates from 1986. Across Washington there are 361,014 housing units, 11 percent of them detached, with a median build year of 1958.^[1]

Owners live in 33 percent of the occupied homes in the ZIP. Projects in a dense area like this tend to be compact: a rear pad off an alley, a strip of planting along a front walk, a patio squeezed between two fences. Many of them need only a few cubic yards of stone or soil, and access matters as much as quantity, so measure the gate or alley width before the truck comes.^[1]

Delivery to a tight site goes smoother with a plan for where the load lands. Lay a tarp or plywood where the truck will dump, keep the pile clear of storm drains, and have wheelbarrows ready so the stone or soil moves into the yard before dark. A loose pile of soil or mulch left uncovered soaks up rain, so cover anything that will sit overnight.^[1]

Sandy loam under the pavement

The USDA soil survey maps the center point of ZIP 20001 as Urban land-Sassafras complex on 0 to 8 percent slopes. Paving and buildings cover 65 percent of that map unit, and Sassafras soil makes up 10 percent. The ground there stands about 70 feet above sea level.^[2],[3]

Where native Sassafras soil remains, its top mineral layer is a sandy loam, rated well drained and placed in hydrologic group B, which means water soaks in at a moderate pace. Shrink-swell in the top 100 cm is low, at 1.8 percent. That combination is about as easy as building ground gets: it packs well, drains without help and does not heave much as it dries out.^[2]

The catch in an old urban neighborhood is what sits above that native soil. Decades of construction leave brick bats, cinders, old footings and mixed fill in many yards, and a fill layer can drain far worse than the sandy loam beneath it. Dig a test hole first. If you hit dark, compacted debris, plan to remove it from the footprint of a patio or pad and replace it with packed Road Base.^[2]

Winter nights below freezing

The NOAA normals station at Natl Arboretum DC, MD, about 3 miles away, records 84 days a year with a low of 32 F or colder. The median last spring freeze there comes on March 29, and the median first fall freeze on November 8. The same station averages 9.7 inches of snow and 45.6 inches of total precipitation a year.^[4]

Many of those cold nights are followed by days above freezing, so water in a base can freeze and thaw again and again. Each cycle pushes up any material that holds water, which is how a paver patio turns wavy and how a gravel pad grows potholes. The defense is a base that drains: open-graded stone or a dense, well-packed layer over a sandy subgrade that lets meltwater escape downward.^[2],[4]

Snow plowed or shoveled off a small pad tends to end up piled along one edge. As it melts, that water needs a path, so pitch the pad toward a planting strip or a small trench of Drain Rock rather than toward the house or the neighbor's wall.^[4]

Building a patio or alley pad

For a paver patio on sandy loam, excavate to firm native soil, lay a light geotextile if you found fill, and build the base from Road Base or 3/4" Crushed Stone in compacted lifts. Screed a thin bed of Concrete Sand on top, set the pavers, and sweep more sand into the joints. A firm edge restraint on all sides keeps freeze and thaw from spreading the field.^[2],[4]

An alley parking pad takes the same base with a different top. Driveway Gravel locks into a firm surface that a car can back across without spraying stones into the alley. #57 Crushed Stone drains faster and works well where water pools, though it moves more under a turning tire, so a steel or timber border helps it stay put.^[2]

Low shrink-swell, at 1.8 percent, means a well-built paver field or flagstone walk on native sandy loam holds its shape for years. Trouble on these sites tends to trace back to poor drainage or a thin base rather than to the soil moving.^[2]

A small dog run or side passage can take Pea Gravel or Stone Dust Screenings. Screenings pack nearly as flat as a sidewalk and are easy to sweep. Pea Gravel is gentler on paws and bare feet, and it drains instantly.^[2]

Tree boxes and planting strips

Street tree boxes and the narrow strips between sidewalk and curb take a beating from foot traffic, salt and compaction. Where the soil in a box has packed hard, loosen the top layer with a fork without cutting roots, then add a shallow layer of Garden Soil mixed with Compost. Finish with Wood Chips or Brown Shredded Mulch, kept clear of the trunk, so rain soaks in rather than running onto the pavement.^[2]

Winter salt from sidewalks drains into these strips with every thaw. A mulch layer helps by holding moisture that dilutes it, and a low border of stone or metal keeps both mulch and soil from washing onto the walk. In a strip too shaded or trampled for plants, Pea Gravel or River Rock gives a clean, open cover that still lets water reach the tree roots.^[4]

Front gardens, downspouts and rain gardens

With 45.6 inches of precipitation a year at the Arboretum station, roof water is the biggest garden problem on a small lot. A downspout that dumps onto bare soil carves a hole and splashes mud onto the wall. A splash basin of River Rock, or a short trench of Drain Rock that carries the flow to a planting bed, keeps the water working for you.^[4]

Sandy loam drains quickly and holds less food than a heavier soil, so a front bed benefits from a few inches of Compost worked in each spring. Fresh Garden Soil suits tree boxes and raised planters. Black Shredded Mulch or Brown Shredded Mulch on top keeps the soil cool in summer and stops winter rain from crusting the surface.^[2]

Sandy loam in hydrologic group B suits a small rain garden. Dig a shallow basin in a low corner of the yard, several steps from the house, and line the inlet with River Rock so downspout water slows as it enters. Fill the basin with a loose blend of Topsoil and Compost, plant it with species that tolerate both soaking and dry spells, and let it hold storm water while it seeps away.^[2],[4]