Asphalt Paving in Antioch, CA

Asphalt paving in Antioch has to cope with a climate that is closer to the Central Valley than to San Francisco. Antioch is classed as semi-arid: the average high in July is 91.1 degrees, the record is 117, and most of the year's 13.22 inches of rain falls in winter, with January the wettest month. Asphalt softens in that kind of heat and stiffens and dries out over years of sun, while winter storms soak the soil beneath it. A driveway or lot that is laid at the right thickness on a firm, well-drained base handles both seasons. One that is laid thin on soft ground ruts in summer and cracks after the rains.

The ground under Antioch

Soil changes across the city. Geology studies prepared for the City of Antioch describe sandy Delhi soils with low shrink-swell potential near East Antioch Creek, but also Capay clay, Diablo clay and Los Osos clay loam, all rated high for shrink-swell, plus large areas of silty clay loam rated moderate. Clay swells when winter rain soaks into it and shrinks as it dries through the summer, and that movement is passed straight up into a pavement that sits on it.

Cost guides describe a typical residential build as 2 to 3 inches of compacted asphalt over 6 to 8 inches of compacted gravel base, with more of both for heavy vehicles and 4 inches or more for commercial lots. Contra Costa County's own minimum for an asphalt driveway in its road right-of-way is 2 inches of asphalt over 6 inches of Class 2 aggregate base. On clay we check the subgrade first, dig out soft material and set the base deep enough to bridge the movement.

Heat, timing and new asphalt

Hot mix has to be rolled while it is workable, and in an Antioch July it stays soft for a while after rolling. We plan summer paving for the cooler part of the day, keep traffic off until the surface has cooled, and give you plain instructions: no turning wheels while parked, no kickstands or trailer jacks on the new mat for the first weeks. In winter the issue is rain rather than cold, so we schedule around storms and keep the base dry before paving.

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Permits for the driveway approach and street

The strip between the street and your property line is public right-of-way. The City of Antioch requires an encroachment permit for any construction in the right-of-way and issues it only to the adjacent property owner or a State-licensed contractor. Its instructions call for a deposit of 100 percent of the job value or $500, whichever is greater, liability insurance naming the City, a 24-hour notice before inspection and a call to USA North 811 before digging. Most driveway work stays on your side of the line and needs none of this. If you want a wider curb cut or a new approach, we explain the process at the estimate before anything is scheduled.

What a typical job includes

• Measuring the area and checking slope, low spots and the transitions at the garage and street
• Removing old asphalt, concrete or gravel and hauling it off
• Replacing soft clay subgrade with compacted aggregate
• Grading the base so water sheds to the yard or gutter, not toward the house
• Placing and rolling hot-mix asphalt to the thickness written in the quote
• Finishing edges so they are supported instead of crumbling into the landscaping
• Care instructions, and a note on when the surface can be sealcoated

Keeping pavement in shape

Sun is the main thing that ages asphalt in a dry climate. It oxidizes the binder, turns the surface gray and brittle, and opens fine cracks that let the winter rain into the base. A sealcoat every few years and crack sealing before the rainy season slow that down. For lots and shared drives, we can set up a sealcoat and restripe on one visit so the property is only closed once.

Antioch is home base. We also pave in Pittsburg, Bay Point, Oakley, Brentwood, Discovery Bay, Knightsen, Byron and Bethel Island, west toward Concord, Clayton, Martinez and Pleasant Hill, and across the river and county lines to Rio Vista, Benicia, Tracy and Mountain House. Conditions change quickly across that area: Delta islands and waterfront communities behind levees, older neighborhoods along the river, newer tracts on the clay toward the hills, and farm roads in the far east of the county. Each city sets its own right-of-way permit rules, and unincorporated communities fall under Contra Costa County Public Works. The town pages cover what is specific to each place.