Gravel, Stone and Soil Delivery in Daly City, CA

Steep slopes and rock close to the surface

The USDA survey maps the Barnabe-Candlestick complex, 30 to 75 percent slopes, at the ZIP's center point. Slopes in that range are steep enough that loose soil and stone move downhill on their own after heavy rain. The Barnabe series makes up 45 percent of the unit.^[1]

The survey lists lithic bedrock at about 12 inches below the surface. Lithic means hard rock, the kind a shovel cannot cut. The top mineral layer is very gravelly sandy loam, a thin, stony soil. A planting hole or a post hole on ground like this often stops at rock within a short dig.^[1]

Barnabe is rated well drained, yet it sits in hydrologic group D, with very slow infiltration and high runoff. The shallow rock explains the match: water moves through the thin soil fast, then hits rock and has nowhere to go but sideways and down the slope. Shrink-swell is low, at 1.5 percent. The ground at the center point stands at 1,140 feet above sea level.^[1],[2]

Mild weather at San Francisco Oceanside

Weather normals come from the NOAA station at San Francisco Oceanside, CA, about 5 miles away. It averages 20.6 inches of precipitation a year and 0.0 inches of snow. Most rain falls in the cool season, and on steep, rocky ground it runs off quickly. A storm can carry loose soil and fine gravel down a slope in one afternoon.^[3]

The station counts just 1 day a year with a low of 32 F or colder. Frost heave is rarely a concern, so a path or a pad here fails from runoff and gravity rather than freezing. Every plan below starts with holding material on the slope and steering water.^[3]

Holding stone on a steep lot

Loose gravel on a slope of 30 to 75 percent will not stay put. Turn the slope into flat shelves first. Low walls of stacked block, stone or timber hold back level terraces, and each shelf can then take a path, a bed or a seating area. Behind each wall, a layer of #57 Crushed Stone or Drain Rock lets water drain out instead of building up pressure.^[1]

Walls on shallow rock sit well when their footing rests on firm ground. Where rock sits near 12 inches, a crew may set a wall's base course on a compacted pad of Road Base over the rock surface. Backfill with clean stone, not native soil, so the wall drains.^[1]

Steps tie the terraces together. Stone or timber risers filled with compacted Stone Dust Screenings or Decomposed Granite make firm treads. 3/8" Crushed Stone or Walkway Gravel on each landing gives grip in wet weather.^[1],[3]

Runoff, erosion and Riprap

With high runoff from group D soil, water from roofs, steps and paving needs a planned path down the hill. A lined channel of River Rock or Riprap carries it safely, and larger Riprap at bends and at the bottom stops the flow from cutting a gully. Never send downspout water straight onto bare soil on a steep slope.^[1],[3]

Bare soil on a hillside is the weak point in the rainy months. Cover it with mulch, plants or stone. Wood Chips knit into a mat that resists washing better than fine mulch on a grade. On the steepest banks, 1-1/2" Crushed Gravel or #4 Crushed Stone over fabric holds the surface while plants take root.^[1]

Check the hillside after the first big storm of the wet season. Look for spots where water has cut a small groove or left a fan of soil at the bottom. Those are the places to add a stone check, a short row of Riprap laid across the flow line, which slows the water and catches soil before it reaches the street. A few checks set early can save a full slope repair later in the season.^[1],[3]

Garden beds on thin, stony soil

Very gravelly sandy loam over shallow rock gives roots little room. Raised beds filled with Garden Soil add the depth most plants need. Topsoil mixed with Compost builds up planting pockets on terrace shelves. Brown Shredded Mulch, Black Shredded Mulch or Red Mulch on top holds moisture through the dry months.^[1]

Fill Dirt levels the floor of a new terrace before the bed mix goes in. Fill Sand beds a drain pipe, and Concrete Sand sets pavers on a flat landing. Pea Gravel makes a soft floor for a bench at the top of the yard with a view. Playground Sand fills a play area on a level shelf.^[1]

Parking pads and drives on a hillside lot

Many homes on steep streets park on a short pad cut into the slope. The cut exposes the thin, stony soil and often reaches rock near the 12 inch layer the survey lists. That rock makes a firm floor, but water running down the hill will meet it and flow out across the pad, so the uphill side needs a drain.^[1]

Set a trench of Drain Rock or #57 Crushed Stone along the uphill edge of the pad, lined with fabric, with an outlet at one end. Build the pad itself from Road Base or Crushed Concrete in compacted lifts, then top it with 3/4" Crushed Stone or Driveway Gravel. Asphalt Millings pack into a firm crust that sheds water well on a short, sloped pad.^[1]

Keep the surface of a sloped pad from becoming a channel. A slight cross slope sends water to the side drain instead of down the middle, and a curb of set stone or timber at the downhill edge stops gravel from spilling onto the sidewalk. Railroad Ballast makes a strong toe for a fill slope below a pad, where heavy, angular pieces lock into the bank.^[1],[3]

Delivery on a steep street needs a safe spot for the truck to tip. A flat driveway apron or a level street edge works best. Plan the route from the pile to the work area, since moving stone uphill by wheelbarrow is slow. Downhill moves go faster, so a pile placed above the job saves time.^[1]

Homes in ZIP 94014 and Daly City

The Census counts 15,941 housing units in ZIP 94014. Detached single-family houses make up 36 percent of them, and owners occupy 60 percent of the occupied homes. The median home in the ZIP was built in 1966.^[4]

Daly City as a whole has 35,922 housing units, with 49 percent detached houses and a median build year of 1965. For the stone layer under state highways, Caltrans names Class 2 Aggregate Base, Section 26-1.02B, Standard Specifications (2026). On a hillside drive or pad, the same dense, compacted stone layer carries the load.^[4],[5]