Bulk Gravel, Stone and Garden Soil Delivered in Tacoma, WA

Gravelly Loam on a Built Hillside

The USDA soil survey places the center point of ZIP 98402 inside a map unit named Urban land-Alderwood complex, 5 to 12 percent slopes. Pavement and buildings account for about 60 percent of that unit, so a good share of the native ground there lies under streets and foundations. Alderwood is the main named soil series in the unit, at 15 percent of it.^[1]

Where the Alderwood soil does reach daylight, its top mineral layer is a gravelly sandy loam. Surveyors rate it moderately well drained and put it in hydrologic group A, the class in which water soaks in fast and little runs off. Its shrink-swell rating is low, at 0.8 percent in the top 100 cm. Put together, that describes a forgiving subgrade: a compacted stone layer on it has little swelling clay to push against, and rain sinks in rather than sitting on top.^[1]

Go deeper and the story shifts. The survey records densic material, a hard, tightly packed layer, at about 35 inches down. Water that moves quickly through the loose loam above can stall and spread sideways when it meets a layer like that, which matters for a French drain or a dry well more than for a shallow driveway. For reference, the USGS elevation service reads the ground at that center point as 380 feet above sea level.^[1],[2]

Rain Totals and Freeze Dates at the Tacoma #1 Gauge

Weather numbers here come from the NOAA normals station called Tacoma #1, WA, which sits about 3 miles from the center point. That gauge logs an average of 40.8 inches of precipitation each year. In this part of the Northwest much of it can fall as long runs of light rain instead of short downpours, so soil can stay damp for weeks at a stretch.^[3]

Hard cold shows up less. Tacoma #1 averages 27 days a year when the overnight low drops to 32 F or below. The median last spring freeze at that gauge comes on March 8. Its median first fall freeze is November 14.^[3]

Long damp spells bring a quieter problem as well. Moss, leaf litter and weed seed settle into a gravel surface that rarely dries out, and over time they fill the gaps between stones. A fresh top-up of clean stone every few years, raked level, keeps the surface open and draining instead of turning green and spongy.^[3]

Read those figures next to the soil and a pattern appears. Steady rain on a quick-draining group A soil is easy to live with on open ground, yet the water still needs a route once it meets pavement, a roof edge or that dense layer below. A gravel surface that is crowned, edged and given a stone-filled outlet at its low side lasts much longer through a wet winter than one laid flat.^[1],[3]

Laying a Driveway on a Grade

The map unit carries its slope range in its name, 5 to 12 percent, and grade is the first thing to plan for on any drive here. Round stone rolls downhill under tires, so angular crushed material is the better pick for anything that climbs. Road Base, a blend of crushed stone and fines, packs into a tight layer that resists sliding, and it pairs well with a gravelly sandy loam subgrade because the two key into each other.^[1]

A sound build on this ground goes in layers. Strip sod and dark organic soil first, then compact the moderately well drained subgrade beneath. Spread Road Base in thin lifts and roll each one before adding the next. Finish with a wearing course of 3/4" Crushed Stone or Driveway Gravel, which gives grip and lets water pass down to the base. With a low shrink-swell rating, the soil itself is unlikely to shove that base around from one season to the next.^[1]

On a sloped drive, running water is a bigger threat than frost. Twenty-seven freezing days a year at the gauge make heave a minor worry, but 40.8 inches of precipitation sliding down a grade can carve ruts fast. Cut a shallow swale along the uphill edge, or set a band of #57 Crushed Stone across the drive at a few points, to turn water aside before it builds speed.^[3]

Homes Near the Heart of the City

ZIP 98402 holds 5,007 housing units by the Census Bureau's American Community Survey. Only 2 percent of them are detached single-family houses. The median home in the ZIP was built in 1988. Owners occupy 18 percent of the lived-in homes.^[4]

The city as a whole looks different. Tacoma counts 97,298 housing units in that same survey, and 61 percent of them are detached houses. The citywide median build year is 1967, a generation older than the ZIP figure.^[4]

Gravel Valet works both kinds of places. A downtown order might be a few yards of River Rock for a courtyard or Garden Soil for a row of planters, while a house lot elsewhere in the city may need a full driveway base. Washington's transportation department sets its own rules for the stone layer under state pavement in Crushed Surfacing Base Course, Section 9-03.9(3), of its Standard Specifications M 41-10 (2027).^[4],[5]

Drain Rock or Pea Gravel for a Soggy Corner

A low corner that stays wet after rain is a common complaint on built-over ground. On this soil the cause may be the dense layer near 35 inches or packed fill close to the surface, either of which stops water the gravelly loam above would pass along. A trench lined with filter fabric and filled with Drain Rock gives that water a clear channel out to a lower spot.^[1]

Pea Gravel is the other stone people ask about for wet spots. Its small, smooth pieces drain freely and look neat around a downspout or a patio edge, but they shift underfoot and never lock together. Drain Rock is larger and more open, so it moves water faster and belongs inside the trench. Plenty of yards use both, with Drain Rock below grade and Pea Gravel as the visible top dressing.^[1]

For beds, a median last spring freeze of March 8 lets planting begin early in the year. Fill raised boxes with Garden Soil, or blend Topsoil with Compost for in-ground beds, then top them with Brown Shredded Mulch so winter rain does not crust the surface.^[3]

Garden paths are a good use for the fast-draining character of this ground. A walk of Stone Dust Screenings or Decomposed Granite, packed over a thin layer of Road Base, stays firm in damp weather because the gravelly loam beneath lets water slip away. Edge the path with steel or timber so the fine surface does not creep into the lawn, and give it a slight crown so puddles do not form in the middle after a long, gray week.^[1]