Gravel Delivery in Arizona

Most of the Valley sits on old valley fill: layers of gravel, sand, silt and clay washed down from the mountains over a very long time. The state geologic map lists that mix at the center points of Phoenix, Mesa, Scottsdale, Chandler, Gilbert, Glendale and Tempe, in slightly different order at each one. Tucson's center point shows sand, silt and clay. Fill of this kind is the same source that much of the region's sand and rounded gravel is dug from, so River Rock and washed sand are at home in a desert yard.^[1]

The USDA survey classes the surface soil well drained at every center point it reads in our Arizona cities. The texture varies. Phoenix, Mesa, Scottsdale and Glendale read loam. Chandler reads sandy loam and Gilbert reads clay loam. Tucson's center point reads gravelly fine sandy loam. Loam is a balanced mix of sand, silt and clay. Clay loam has more clay in it, so it packs harder and swells a bit when wet, while sandy loam is loose and easy to dig.^[2]

The ground at Phoenix's center point stands 1,090 feet above sea level. The other Valley center points fall close to it: Glendale at 1,150 feet, Tempe at 1,170 feet, Chandler at 1,200 feet, Mesa at 1,210 feet, Gilbert at 1,220 feet and Scottsdale at 1,270 feet. Tucson's center point is far higher, at 2,400 feet.^[3]

For a buyer, desert ground is forgiving in some ways and tricky in others. Well drained soil does not stay soggy, so a base sits on firm footing most of the year. Desert soils can also hide a hard, limy layer a short way down that blocks roots and water. Dig a test hole where you plan a tree or a drain. If you hit a white, rock-hard crust, plan to break through it or move the hole.^[2]

Dry weather makes most drops easy. The weather station used for Phoenix averages 7.2 inches of precipitation a year. The stations for Mesa, Chandler, Gilbert and Tempe each average 8.8 inches, Scottsdale's 8.7 inches and Glendale's 8.3 inches. Tucson's station averages 11.6 inches. When rain does come, it can fall hard and fast in a summer storm, and a wash or a low street can run with water for an hour or two.^[4]

Cold is rare. The Phoenix station logs 1 day a year at 32 F or colder. Scottsdale's logs 3 days, Glendale's 4 days and Tucson's 5 days, while the stations for Mesa, Chandler, Gilbert and Tempe each log 10 days. Snow averages 0.0 inches at the stations for Tucson, Mesa, Chandler, Gilbert, Glendale and Tempe. Frost heave is not a real concern for a desert drive. Sun and heat are, so plan to spread mulch and soil in the cooler part of the day.^[4]

Access is the usual limit. Many Valley homes have block walls, side gates and narrow side yards, and a dump truck cannot reach a backyard through them. Most loads are tipped on the driveway or at the curb where that is allowed, then moved by wheelbarrow or a small loader. Measure the gate before ordering if you hope to use a skid steer. Watch for overhead lines and palm fronds above the drop spot.^[2]

Protect the driveway itself. Concrete in the sun can be stained by wet soil, mulch or Compost, and a sharp stone load can scuff a fresh sealer. Lay a tarp before the load lands, and sweep and hose the drive once the pile is moved. On the clay loam mapped at Gilbert's center point, a lawn edge soaked by irrigation can be softer than it looks, so keep the truck on the hard surface.^[2]

Heat changes how materials handle on the drive. Dark stone and Asphalt Millings get very hot in afternoon sun, and a pile of Road Base dries out fast, which makes it harder to pack. Plan to spread and wet base material in the morning. Keep a hose close by, since dry fines need water to bind into a firm layer.^[4]

Desert landscaping is the biggest use. A rock yard starts with clean grading and weed fabric, then a cover layer of decorative stone. Decomposed Granite is the classic choice: it packs into a firm, natural looking surface for paths and open areas. River Rock and Pea Gravel suit beds, borders and dry creek beds. #57 Crushed Stone and 3/4" Crushed Stone give a crisper, angular look around cactus and desert shrubs.^[2]

Driveways and parking pads come second. On well drained loam like the survey maps at Phoenix's center point, a drive needs less digging than in wet climates, but it still needs a packed base. Spread Road Base or Crushed Concrete in lifts, wet each one and pack it, then top it with Driveway Gravel or Decomposed Granite. Asphalt Millings make a firm, dark surface for an RV pad. Watering the base while packing matters in dry country, because dry fines will not lock together.^[2]

Drainage still matters, even with 7.2 inches of yearly precipitation at the Phoenix station. Storms can drop that water quickly, and a roof or a patio sends it to one spot. A dry creek bed of River Rock with a few larger stones carries runoff across a yard and looks good when dry. A gravel trench of Drain Rock along a wall takes water from downspouts. Riprap holds the slope where a wash or channel turns.^[4]

Patios, walkways and play areas take smaller loads. Pavers sit on packed Road Base with a thin layer of Concrete Sand or Stone Dust Screenings. A Decomposed Granite path between steel edging is firm enough for a wheelbarrow. Playground Sand fills a sandbox, and Wood Chips under a swing set soften falls and stay cooler under foot than bare rock in summer.^[2]

Garden beds and trees need real soil. Desert ground is often low in organic matter. Mix Compost or Garden Soil into the planting hole, and use Topsoil to build up a raised vegetable bed. A layer of Brown Shredded Mulch or Wood Chips over the root zone slows evaporation and keeps the soil cooler. Clay loam like the survey shows at Gilbert's center point holds water longer, so it needs less frequent watering than the sandy loam mapped at Chandler's.^[2]