Gravel, Stone and Soil Delivery in Vallejo, CA

Rincon clay loam and what it does to a base

The USDA soil survey maps Rincon clay loam, 0 to 2 percent slope, at the ZIP's center point. The Rincon series fills 85 percent of that map unit, so its clay loam top layer is the ground worth planning around. Clay loam packs tight and hard while it stays dry, then goes slick and soft once it soaks up a storm. Gravel spread straight onto Rincon clay sinks in the wheel paths, because the clay squeezes up between the stones while the stones press down into the clay.^[1]

Shrink-swell in the top 100 cm is rated high, at 6.8 percent linear extensibility. Rincon ground grows as it wets and pulls back as it dries, and that slow heaving can crack a slab, lift a paver edge or tilt a timber border. Loose aggregate handles the motion better than concrete does, since each stone can shift a hair and settle again without breaking. The survey still calls the Rincon soil well drained, meaning water works its way down through the profile rather than ponding in it for days, so the swelling comes and goes with the weather.^[1]

Rain, freeze dates and the Vallejo station

Weather normals come from the NOAA station at Vallejo, CA, about 4 miles from the ZIP. Its yearly average is 21.5 inches of precipitation. On a clay loam with a high swell rating, that much rain is enough to soften the subgrade through the wet part of the year and then let it bake firm again, so a driveway base has to stay stable in both conditions.^[2]

The Vallejo station logs only 4 days a year with a low of 32 F or colder. With so few hard nights, frost heave barely figures in the plan, and water is the thing that breaks down a gravel surface here, not ice.^[2]

At that station the median last freeze date is January 17 and the median first freeze date is December 27. Planting, seeding and bed work can follow the rain and your own schedule for most of the year, with frost a minor worry.^[2]

A driveway built to ride over swelling clay

Strip the dark surface soil and roots until you hit firm clay loam, then shape the subgrade with a gentle crown so water drains to the sides. Roll out woven fabric across the whole footprint. On high shrink-swell ground the fabric stops clay from creeping up into the stone and lets the base bridge small soft pockets. The hydrologic group C rating, slow infiltration, tells you rain enters the surface slowly, so getting the crown right pays off more here than on sandy ground.^[1]

Spread Road Base over the fabric in thin lifts and compact each one with a plate or roller until a boot heel barely marks it. Its angular pieces interlock and its fines pack into the gaps, which is why it sets up hard. Crushed Concrete can stand in for that layer, as it compacts in much the same way. Finish with 3/4" Crushed Stone or Driveway Gravel for grip. Keep the top a little higher than the lawn beside it, because a drive that sits low on clay loam collects runoff from every direction.^[1]

Where the drive meets a downspout or a low corner, dig a shallow trench, line it with fabric and fill it with Drain Rock. At 21.5 inches of yearly rain the trench will sit dry most weeks, yet in a heavy storm it pulls water away before it can soften the base.^[1],[2]

Garden beds on slow-draining ground

Because water enters a group C soil slowly, plants set straight into the clay loam can sit wet at the root after a storm and then crust over as the surface dries. A raised bed solves most of that. Fill it with Garden Soil, or blend Topsoil with Compost, and fork some Compost into the clay underneath so the two layers do not meet at a hard line that roots refuse to cross.^[1]

High shrink-swell clay opens cracks through the dry months. A blanket of Brown Shredded Mulch or Wood Chips shades the bed and slows the drying, so the ground moves less and the cracks stay thin. Black Shredded Mulch and Red Mulch give the same cover in a darker or warmer color against the house.^[1]

The survey point stands 20 feet above sea level. The Rincon map unit lies on a 0 to 2 percent slope, which leaves little natural fall to carry water off a bed, so a narrow strip of Pea Gravel or River Rock along the foundation is worth adding. It keeps splash off the siding and lets roof water spread out before it reaches the plants.^[1],[3]

Decomposed Granite or Walkway Gravel for a side yard

Narrow side yards are where many Vallejo owners give up on grass, and the two stones that come up most for them are Decomposed Granite and Walkway Gravel. On Rincon clay loam, the deciding question is how each path handles water. Decomposed Granite packs into a tight, smooth floor, so rain runs across it rather than into it, and on slow group C ground that runoff has to be sent somewhere. Give a Decomposed Granite path a slight cross slope and a gravel strip at its low edge.^[1]

Walkway Gravel stays a little looser, which lets water pass down to the base and lets the stones shuffle as the clay below swells and shrinks. Cracks that would show in a packed surface close up again in loose stone. For a side yard that carries trash bins and a wheelbarrow, either one works best over two or three compacted inches of Road Base on fabric. Pick Decomposed Granite when a clean, level look matters most, and Walkway Gravel when the path crosses a low spot that stays damp after rain.^[1]

Stone Dust Screenings sit between the two: finer than Walkway Gravel, looser than Decomposed Granite once compacted. They also make a good setting bed for stepping stones laid across the Rincon clay.^[1]

Homes in ZIP 94589 and the state base standard

The Census counts 9,996 housing units in ZIP 94589. Detached single-family houses make up 79 percent of them. Vallejo as a whole holds 47,084 housing units, and 69 percent of those are detached houses.^[4]

The median home in ZIP 94589 dates from 1974, and the median for the city is 1975. Owners live in 60 percent of the occupied homes in the ZIP. Yards lived in for decades tend to need a refresh rather than a rebuild, such as a fresh inch of Walkway Gravel on a tired side path or Decomposed Granite to firm up a seating area.^[4]

Caltrans sets out Class 2 Aggregate Base in Section 26-1.02B of its Standard Specifications (2026). That section covers the compacted stone layer under state highways, and it rests on the same idea as a good home drive: a dense, well-graded layer packed hard beneath the surface.^[5]