Gravel, Stone and Soil Delivery in Fairfield, CA

Clay loam through wet and dry months

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 the map unit. Its top mineral layer is clay loam, a heavy soil with enough clay to feel sticky and hold its shape when squeezed wet.^[1]

Shrink-swell in the top 100 cm is rated high, at 6.8 percent linear extensibility. Through the wet months, the clay soaks up water and swells. As the ground dries out, it shrinks and opens cracks that can run deep enough to swallow a trowel. That seasonal motion lifts and drops anything rigid laid on top, and it is the main force behind tilted pavers and cracked concrete.^[1]

The survey rates the Rincon soil well drained and places it in hydrologic group C, slow infiltration. The two ratings describe different things. Water that soaks in moves on through the profile rather than staying trapped, but the clay surface lets it in slowly, so a heavy rain runs off before much of it enters. On a 0 to 2 percent slope, that runoff has little fall to carry it away, and it gathers in low spots.^[1]

A shovel tells you when the clay is ready to work. Squeeze a handful: if it smears and sticks, it is too wet to compact or dig cleanly, and if it crumbles into hard clods, it is too dry. Clay loam that holds a ball but breaks apart under thumb pressure is at the right moisture for grading and compaction, and work done at that point lasts.^[1]

Valley weather at the Fairfield station

The NOAA normals station at Fairfield, CA, about 3 miles from the ZIP, averages 24.5 inches of precipitation a year and 0.0 inches of snow. Rain is the force that matters here, and clay loam reacts to it more than any other soil type.^[2]

The station records 8 days a year with a low of 32 F or colder. A handful of frosty nights can damage tender plants, but frost does not drive deep enough to heave gravel or pavers.^[2]

At the Fairfield station, the median last freeze date is January 15 and the median first freeze date is December 14. A frost cloth over tender plants on the coldest nights near those dates protects them well.^[2]

The ground at the center point stands 70 feet above sea level.^[3]

Rain at a station that averages 24.5 inches a year can arrive in strong storms, and slow-entry clay sends much of a hard storm across the surface. Grading the yard so water leaves the house in every direction is the first job on any lot, before a single load of stone arrives.^[1],[2]

Concrete, pavers or stone on swelling ground

The surface you choose for a patio or a drive decides how well it handles clay that moves. A poured slab is one rigid piece. When the ground below swells unevenly, the slab has no way to flex, so it cracks or tilts. Pavers handle movement better, since each unit can shift a little and be reset, but they need a deep, compacted base and fabric so clay does not pump up through the joints.^[1]

Loose stone handles motion best of all. A drive or a path of 3/4" Crushed Stone, Driveway Gravel or Decomposed Granite settles when the clay shrinks and rides up when it swells, and a rake puts it right in minutes. For owners on high shrink-swell ground who want low upkeep, a well-built gravel surface can outlast a slab. Whichever surface you pick, the base underneath and the drainage around it carry most of the load.^[1],[2]

Edges also need thought on moving clay. A paver patio needs a firm restraint along every side, set in the compacted base rather than in the soil, so the outer row does not creep outward as the clay swells. A gravel path or drive needs a border of steel, timber or set stone for the same reason.^[1]

Building the base layer by layer

Strip the topsoil and roots, and shape the clay loam into a gentle crown so water drains to the sides. Compact it while it is moist but not soaked. Roll out woven fabric across the full footprint, overlapping the seams. On swelling clay, this layer keeps the soil and the stone apart, and that does more for the finished surface than any other step.^[1]

Spread Road Base in thin lifts and pack each one with a plate compactor. Crushed Concrete works well in place of Road Base. For a drive that carries heavy vehicles, put a course of 1-1/2" Crushed Gravel or #4 Crushed Stone under the Road Base to spread the load. Finish with the surface of your choice. At the low edge, dig a narrow trench, line it with fabric and fill it with Drain Rock, so runoff from the 24.5 inches of yearly rain leaves the site instead of soaking the clay under the base.^[1],[2]

A path that crosses a low spot can double as a drain. Dig the trench a little deeper there, line it with fabric, fill the lower part with Drain Rock and finish the top with 3/8" Crushed Stone or Walkway Gravel. Water that gathers in the low spot sinks into the stone and moves along the trench, and the walking surface stays firm.^[1]

Lawns, beds and trees on clay loam

Clay loam holds nutrients well but drains slowly at the surface. Raised beds filled with Garden Soil give vegetables and flowers a fast-draining root zone. For in-ground beds, fork Compost deep into the clay each year to open it up. A lawn benefits from a thin topdressing of Topsoil mixed with Compost after aeration.^[1]

Brown Shredded Mulch or Wood Chips over the soil slow drying, which keeps cracks narrow, and they break up the force of rain so the surface does not seal. Black Shredded Mulch and Red Mulch work the same way. Keep mulch a few inches from trunks and stems. Along the foundation, a strip of River Rock or Pea Gravel over fabric keeps roof runoff from soaking the clay next to the wall.^[1],[2]

Trees on swelling clay draw water from the soil around them, and in dry weeks that can make the ground shrink more near the trunk. Plant new trees well back from slabs and foundations, give them a wide mulched ring, and water them deeply and evenly. Even moisture is the best way to keep clay loam from swinging between swollen and cracked.^[1],[2]

Homes in ZIP 94533 and the Caltrans base standard

The Census counts 26,060 housing units in ZIP 94533. Fairfield holds 40,391 units in all.^[4]

Detached single-family houses make up 64 percent of homes in ZIP 94533, compared with 69 percent for Fairfield.^[4]

The median home in ZIP 94533 was built in 1979, and the citywide median is 1986. Owners occupy 56 percent of the occupied homes in the ZIP.^[4]

The California Department of Transportation sets its base standard as Class 2 Aggregate Base, Section 26-1.02B, in the Standard Specifications (2026). It describes the graded stone layer under state roads.^[5]

ZIP 94533 is in Solano County, and Gravel Valet also delivers to Vacaville, Concord and Antioch.^[5]