Gravel, Stone and Soil Delivery in Hollister, CA

Cobbly clay and rock in the hills

The mapped center point of ZIP 95023 lies in rough hill country. The soil survey maps it as Cibo-Rock outcrop complex, 30 to 75 percent slopes, eroded. Cibo soil fills 55 percent of the unit, and bare rock shows at the surface across much of the rest.^[1]

Cibo's top mineral layer is cobbly clay, a heavy soil studded with large stones. Lithic bedrock lies about 21 inches below the surface. The survey rates the soil well drained, yet places it in hydrologic group D, where water soaks in very slowly and runs off fast. Thin clay over rock has little room to store rain.^[1]

Shrink-swell in the top 100 cm is moderate, at 5.5 percent. Clay like that cracks when it dries and swells when it wets, so a base laid on it needs fabric and enough depth to bridge the movement. The ground at the center point stands 3,460 feet above sea level, well above the valley floor where most homes sit.^[1],[2]

Most homes in the ZIP stand on the flatter valley ground below the hills, where the soil can be deeper and less stony. Test holes on your own lot tell you what you have. Heavy, sticky soil that holds a thumbprint is clay and needs fabric. Crumbly, gritty soil drains better and needs less.^[1]

Very little rain at San Luis Dam

Weather normals come from the NOAA station San Luis Dam, CA, about 13 miles away. It averages 10.4 inches of precipitation a year and 0.1 inches of snow. The low reaches 32 F or colder on about 12 days.^[3]

Frost there is brief. The median last freeze comes on January 27, and the median first freeze returns on December 11.^[3]

Dry ground for most of the year means stone work deals with dust, sun and the odd hard storm. Clay that is bone dry turns slick and sticky the moment it gets wet, and that is when a poorly built drive ruts. Build for the wet day even in a dry climate.^[1],[3]

Frost dates matter little for stone work here, but they matter for planting. With so few freezing nights at the station, many plants can go in during late winter, as long as the soil is not saturated from a storm.^[3]

A valley drive on clay

For a drive or parking area on clay, dig out the topsoil and soft clay, shape the subgrade with a gentle crown and lay a woven fabric. Fabric is the most useful single step on clay, because it keeps the base stone from pressing into the soil when a winter storm soaks it.^[1]

Spread Road Base in compacted lifts, wetting each one so the fines bind. Caltrans Class 2 aggregate base is the same kind of dense, graded stone. Top it with Driveway Gravel or 3/4" Crushed Stone for traction and quick drainage. On a dusty ranch road, Asphalt Millings harden in the sun and throw less dust than loose stone.^[3],[4]

Where clay ground slopes toward the drive, cut a shallow ditch on the high side and line it with 1-1/2" Crushed Gravel. Runoff from group D soil arrives quickly after a storm, and the ditch keeps it off the base.^[1]

A long ranch drive takes more stone than most people expect. Measure the length and width, choose the depth of each layer and use the area calculator above to size the order. Ordering the base and the top stone together saves a second trip.^[1]

Turnaround areas at the end of a long drive take the hardest wear, from trucks swinging around on the same spot. Build that part a little thicker, with an extra lift of Road Base over the fabric.^[1]

Rocky slopes and erosion

Slopes in the mapped unit reach 75 percent, and the survey marks it as eroded. On hillside lots, bare soil washes off in the first heavy rain of the season. Riprap at the base of a slope and in gullies slows the water and holds soil in place. Set the stones partly into the ground and fit them tight.^[1]

A dry creek bed of River Rock gives runoff a planned path through a yard. Make it wide and shallow, with larger stone on the outside of curves. Behind any retaining wall, backfill with Drain Rock wrapped in fabric so water can drain instead of building pressure.^[1]

Rock outcrops on a hillside lot are worth keeping where they stand. They resist erosion better than any fill, and stone placed around them can blend with the natural ground. Plant the soil pockets between them and cover the bare ground with mulch.^[1]

Choosing between Decomposed Granite and Walkway Gravel

For a garden path in a dry yard, two materials lead the list. Decomposed Granite packs into a smooth, firm surface that looks at home in a California garden. It sets best with a light watering and a roller, and it needs fresh material raked in after a few years. On clay, lay it over a compacted base so the path does not soften in a storm.^[1],[3]

Walkway Gravel is crushed and angular. It stays looser on top, drains at once and never turns muddy. It suits paths near lawns and beds that get regular water. Either choice needs a firm edge of steel, stone or block to keep the material in place.^[1]

Under a paver patio, use compacted Road Base and a bed of Concrete Sand. Sweep Mason Sand or Stone Dust Screenings into the joints.^[1]

Playground Sand or Wood Chips make a safer landing than gravel under swings and slides. Edge the play area so the material stays where children fall.^[5]

Homes, gardens and the state base spec

The Census counts 18,404 housing units in ZIP 95023. Detached single-family houses make up 80 percent of them, and the median home was built in 1990. Owners live in 68 percent of the occupied homes.^[5]

The city of Hollister has 12,921 housing units. Detached houses make up 78 percent, and the median home dates to 1991.^[5]

Clay holds water once it is wet, so raised beds of Garden Soil mixed with Compost give roots better drainage than the native ground. Cover the beds with Wood Chips or Shredded Mulch to slow the summer drying. The state's road base reference is Class 2 Aggregate Base, Section 26-1.02B, in the Caltrans Standard Specifications (2026).^[1],[4]

Detached houses dominate both the ZIP and the city, so most projects here are single-family yard work: a new side yard for a trailer or boat, a gravel play area, or front beds dressed in Red Mulch or River Rock.^[5]