Gravel, Crushed Stone and Soil Delivery in Colorado Springs, CO

Swelling Clay and Shallow Shale

The USDA survey maps the ZIP's center point as Midway-Razor clay loams, dry, 1 to 18 percent slopes. The Midway series makes up 46 percent of that unit, and its top mineral layer is clay loam.^[1]

Shrink-swell in the top 100 cm is rated high, at 7.7 percent. Clay with that rating swells when it soaks up water and shrinks and cracks as it dries out, which lifts and drops anything built on it.^[1]

The survey records paralithic bedrock at about 16 inches below the surface. Paralithic means soft, weathered rock that a pick or a heavy machine can break, but it stops water and roots much like solid rock does.^[1]

Digging into that weathered shale takes a heavy bar or a machine. Post holes for a fence or a deck footing may need a rented auger with a rock bit where the shale comes close to the surface.^[1]

The mapped geologic unit at the center point is the Middle unit of the Pierre Shale, a Late Cretaceous shale with some sandstone. Pierre Shale is well known among builders on the Front Range for swelling when wet.^[2]

The Midway soil is rated well drained, but its hydrologic group is D, with very slow infiltration and high runoff. The shallow shale below holds water up, so rain runs off the surface quickly instead of soaking in.^[1]

Snow, Sun and Many Cold Nights

The NOAA normals station for this ZIP is Colorado Springs Muni AP, CO, about 8 miles away. It averages 15.9 inches of precipitation and 32.5 inches of snowfall a year.^[3]

The airport counts 160 days a year with a low of 32 F or colder. Its median last spring freeze falls on May 3, and its median first fall freeze on October 8.^[3]

Snow under strong sun can melt fast, and that melt soaks into whatever lies below. Water that gets into a clay subgrade and then freezes overnight heaves a surface far more than dry cold ever does.^[3]

Ground height at the ZIP's center point is about 5,890 feet above sea level, by the USGS reading.^[4]

A Driveway That Survives Clay and Frost

On swelling clay, the goal is to keep water away from the subgrade. Strip the topsoil, shape the clay so water runs to the sides, and roll out woven fabric before any stone goes down. A shallow shale layer may limit how deep you can dig, so build up rather than down where it is close.^[1]

Lay a coarse bottom course of #4 Crushed Stone or 1-1/2" Crushed Gravel and compact it, then add a compacted layer of Road Base. The thicker the base, the more it spreads the load and evens out the movement of the clay beneath.^[1]

Finish with 3/4" Crushed Stone, which packs tight and holds on a slope. Avoid round Pea Gravel on any drive with a grade, since it rolls downhill under tires and in snowmelt.^[1]

Asphalt Millings make a firm, dark surface that sheds snow and melts out faster in the sun. Crushed Concrete is a recycled option for the base or for a work area.^[3]

The Colorado Department of Transportation specifies Aggregate Base Course, Class 6, in Section 304 of its Standard Specifications for Road and Bridge Construction 2025. That spec is for highways, but the idea of a graded mix compacted into a dense, stable layer is the same one a driveway relies on.^[5]

Slopes, Runoff and Erosion

Slopes in the soil unit run from 1 to 18 percent, and on a group D soil, rain and melt water head downhill fast. Without a plan, that water cuts ruts in a gravel drive and washes soil out of beds.^[1]

On a sloped drive, add water bars or shallow dips filled with #57 Crushed Stone to turn water off the surface before it gathers speed. Riprap at the outlet of each turnout keeps the runoff from carving a gully.^[1]

Terraces held by block walls turn a steep yard into level beds. Put clean stone such as Drain Rock behind each wall with a perforated pipe at the base, so water does not build up pressure in the clay and push the wall over.^[1]

A dry creek bed of River Rock carries roof and yard runoff to a safe spot and looks natural on a hillside lot.^[3]

Keep stockpiles of soil and stone on the uphill side of a job and covered with a tarp, so a sudden storm does not wash them down the slope and into the street.^[1]

Road Base or Asphalt Millings on a Hillside Drive

Road Base and Asphalt Millings are the two surfaces that hold best on a steep drive. Road Base packs into a hard crust as its fines bind, and it is easy to regrade and top up after a rough winter. It can wash on the steepest pitches if water runs down the drive instead of across it.^[1]

Asphalt Millings bind more tightly once summer sun warms them and traffic presses them, forming a surface close to worn pavement. They shed snowmelt well and hold together on a slope, though they take a warm season to set fully after they are laid.^[3]

On a long hill, a mix can work: millings on the steepest stretch and Road Base topped with 3/4" Crushed Stone on the flatter parts.^[1]

Homes in ZIP 80902

The latest Census survey puts ZIP 80902 at 3,859 housing units. Detached single-family houses make up 12 percent of them, compared with 60 percent across Colorado Springs.^[6]

The median home in the ZIP was built in 2001, while the median across the city's 211,353 housing units is 1986. The Census puts the owner-occupied share of occupied homes in 80902 at 0 percent.^[6]

Newer townhome and apartment grounds can sit on graded fill left after construction. A load of Topsoil and Compost turns that hard, thin ground into a lawn or a planting bed.^[6]

Planting Over Clay and Shale

With shale about 16 inches down, roots have little room. Build raised beds and fill them with Garden Soil, or mix Compost into the clay loam to open it up and help it drain.^[1]

Keep water away from foundations. On a high shrink-swell clay, planting beds that are watered right up against a wall can swell the soil there. Slope the ground away from the house, set beds a few feet out, and use a band of River Rock under the drip line.^[1]

Spread Brown Shredded Mulch, Black Shredded Mulch or Red Mulch after the May 3 median last spring freeze. Mulch holds moisture through dry, windy summers and keeps clay from cracking. Add a fall layer before the October 8 median first freeze.^[3]

Native and drought-tolerant plants handle clay and dry wind better than thirsty lawn grass. A mulch of Decomposed Granite or River Rock around them keeps the soil from drying out in the sun.^[3]

For paths, Decomposed Granite or Walkway Gravel pack into a firm surface. Topsoil fills low spots in lawns, and Fill Dirt raises grades before hardscape goes in.^[1]