Gravel, Stone and Soil Delivery in Urbana, IL

Flat prairie silt that holds water

The soil survey maps Flanagan silt loam, 0 to 2 percent slopes, at the center point of ZIP 61801. Flanagan is almost the whole unit at 95 percent, and only 1 percent is mapped as urban land. Ground this flat gives runoff very little reason to move, so water from a storm tends to sit where it lands.^[1]

The survey rates Flanagan somewhat poorly drained. Its hydrologic group is C/D, which means it acts like group D while the water table is high and like group C where tile or ditches have drained it. Either way, infiltration is slow. The top mineral layer is silt loam, a fine soil that turns soft and sticky when wet.^[1]

Shrink-swell in the top 100 cm is rated high, at 6.5 percent. Soil like that swells as it soaks up water and shrinks and cracks as it dries, and a gravel base laid straight on it will move with it. Plan on a thicker base, a fabric layer and good drainage around the edges. The ground at the mapped center point stands 730 feet above sea level.^[1],[2]

Bedrock far below belongs to the Tradewater Formation, a Bashkirian unit of shale, sandstone, coal and limestone. It lies well under the deep silt, far below the depth of any yard project.^[3]

Cold months at Champaign 3S

NOAA normals come from the Champaign 3S, IL station, about 2 miles from the center point. The gauge averages 40.9 inches of precipitation and 20.8 inches of snowfall a year. Lows of 32 F or colder arrive on about 120 days of the year there.^[4]

The median last spring freeze at Champaign 3S falls on April 15, and its median first fall freeze falls on October 24.^[4]

Wet silt and repeated freezing make a classic recipe for frost heave. Water held in the fine soil turns to ice, expands and lifts the stone above it, then lets it drop in a thaw. A base that is drained and thick enough keeps that water away from the surface. Snow plowed to the side of a drive melts back toward it in spring, so give the melt a path off the edge.^[1],[4]

Snow and freezing nights also slow spring work. Silt loam that is still wet from melt smears and packs into a hard crust under a shovel or a wheel. Wait until the ground crumbles in your hand before you dig or compact, or the subgrade will be weaker than it looks.^[1],[4]

A parking pad that stays level on swelling silt

Dig the pad deeper than you would on sandy ground, removing the dark topsoil and any soft silt until the shovel hits firm subsoil. Lay a woven geotextile fabric across the whole area and up the sides. On silt loam with high shrink-swell, the fabric is the step that keeps base stone from sinking into mud during the first wet spring.^[1]

Build the base with Road Base or Crushed Concrete in several compacted lifts. Where the pad sits in the lowest part of the lot, start with a layer of #4 Crushed Stone or 1-1/2" Crushed Gravel under the Road Base to lift the work above standing water. Finish with Driveway Gravel or #57 Crushed Stone.^[1]

Edges matter on flat ground. A shallow trench of Drain Rock along the low side, wrapped in fabric, gives water from the pad somewhere to go. Without it, rain can move sideways under the stone and soften the subgrade from below.^[1]

Plan the job for late spring or early fall, when the silt is firm and the ground is not frozen. Compaction on dry, firm subsoil gives the base its best start.^[1]

Sidewalk edges, alleys and small rental yards

With owners in only 33 percent of the occupied homes in ZIP 61801, many projects here are landlord jobs: an alley parking strip, a side yard that turns to mud, a worn path to a back door. Each of these comes back to the same slow silt loam, so each job needs a base that sits above the wet layer and drains to the side.^[1],[5]

For an alley parking strip, Crushed Concrete or Asphalt Millings make a hard, durable surface over fabric. Millings bind together in summer heat and form a firm, dark top that sheds rain. A side yard path of 3/8" Crushed Stone over Stone Dust Screenings keeps shoes clean after a storm, and an edge of set stone holds it in place.^[1]

Where a downspout soaks a strip beside the house, a splash pad of River Rock and a short run of Drain Rock carry the water away from the foundation. On flat ground with a C/D hydrologic rating, even a short trench helps.^[1]

Choosing between #57 and #89 stone for drainage work

Drainage is the most common stone job on slow ground like Flanagan silt loam. #57 Crushed Stone, about the size of a grape to a walnut, leaves wide gaps for water and suits French drains, dry wells and the trench behind a wall. #89 Crushed Stone is far smaller and packs tighter, so it works better as a setting bed or a fill around pipe joints.^[1]

In a drain line, wrap the trench in fabric first so fine silt cannot wash into the stone and clog it. Set the pipe on a bed of #57, cover it with more #57, then fold the fabric over the top before replacing the soil. Pea Gravel is smooth and round, so it rolls underfoot. It drains well but locks poorly, so keep it for paths and play areas.^[1]

Shredded Mulch and Wood Chips also help in winter. A layer over perennial beds evens out soil temperature across the many freezing nights at the station, which cuts down on roots heaving out of the ground in a thaw.^[4]

Gardens, rentals and homes in ZIP 61801

Silt loam is rich garden soil once it drains. Raised beds filled with Garden Soil let roots stay above the wet layer in spring, and a top dressing of Compost each fall keeps the beds loose. Shredded Mulch over the beds holds moisture in July and keeps rain from crusting the surface. Plant tender crops after the April 15 median last freeze.^[1],[4]

The Census counts 13,222 housing units in ZIP 61801. Detached houses account for 36 percent of them, and the median home dates to 1973. Owners live in 33 percent of the occupied homes, so many households here rent.^[5]

Across Urbana as a whole there are 19,228 housing units, 39 percent of them detached, with a median year built of 1980. The state's road base reference is Aggregate Base Course, Section 351, in the Illinois Department of Transportation Standard Specifications for Road and Bridge Construction (2022).^[5],[6]