Gravel, Stone and Soil Delivery in Huntersville, NC

Monacan loam on a flood plain

At the center point of ZIP 28078, the USDA soil survey maps Monacan loam, 0 to 2 percent slopes, frequently flooded. Monacan makes up 80 percent of the unit. Its top mineral layer is loam, a balanced mix of sand, silt and clay.^[1]

The words frequently flooded come from the map unit name. Soils like Monacan form along creeks, from silt and sand that floodwater leaves behind. Land in a unit with that name can take on water during big storms, and any project close to the center point should be planned with that in mind.^[1]

The survey rates Monacan somewhat poorly drained and gives it hydrologic group B/D. The split means it behaves like group D, with very slow infiltration, while the water table is high, and like group B, with moderate infiltration, where it has been drained. Shrink-swell is low, at 1.5 percent. Wet ground is the main thing a stone project on Monacan loam has to beat, so every plan below starts with height and drainage.^[1]

Hard rock beneath the creek ground

The state geologic map places a unit of Metamorphosed Quartz Diorite under the center point. Its rock is metadiorite, a hard, dark crystalline rock of Neoproterozoic age.^[2]

Rock of this kind weathers into clay-rich material on the hills around a stream. In the creek bottom itself, the soil on top is mostly water-laid loam. The ground at the center point stands 680 feet above sea level.^[2],[3]

For a builder, that means a trench near the creek may cut through soft, layered loam with sandy streaks and pebbles, left by old floods. Higher up the slope, the same trench may meet stiff red clay and, deeper down, weathered metadiorite. Plan the stone you need for each part of the job instead of assuming the whole lot is the same.^[1],[2]

Rain and freezes from Charlotte Douglas

The NOAA normals station used here is Charlotte Douglas AP, NC, about 13 miles away. It averages 43.6 inches of precipitation and 3.5 inches of snow a year.^[4]

Lows at that station reach 32 F or colder on 58 days a year. Its median last spring freeze is March 30, and its median first fall freeze is November 3.^[4]

Rain and freezing nights hit hardest on wet, low ground. A base that sits in a high water table stays damp, and damp stone that freezes can loosen. Lifting the work above the wet layer and draining it well matters more here than on a hilltop lot.^[1],[4]

Snow is light at 3.5 inches a year near the Charlotte station, but a few cold, wet days in winter can keep low ground soggy for a long time. Spring is the time to check a drive on Monacan loam. Look for ruts, potholes and soft edges after the median last freeze on March 30, and fix them before summer storms arrive.^[1],[4]

Raising a drive above wet loam

On somewhat poorly drained ground, a drive needs height. Strip the topsoil, then bring in Fill Dirt to raise the subgrade above the yard around it, compacting it in thin layers. A raised bed for the drive keeps the base out of the wettest soil.^[1]

Roll out a woven geotextile over the compacted fill. Then lay a coarse first layer of 1-1/2" Crushed Gravel or #4 Crushed Stone, which spreads the load and lets water move out of the base. Add Road Base on top in compacted lifts, and finish with Driveway Gravel or #57 Crushed Stone.^[1]

Give the drive a clear crown and ditches on both sides where you can. If water crosses the drive in a storm, set a culvert pipe or a stone-filled trench at the low point and protect both ends with Riprap. A drive on flood-prone ground that lets water pass under it lasts far longer than one that tries to dam it.^[1]

After any flood, inspect the drive. Water that ran across it may have washed fines out of the surface or left a layer of silt on top. Rake the silt off, refill any low spots with Road Base, compact them, and spread fresh Driveway Gravel. A quick repair keeps a small washout from growing.^[1]

Patios and beds on low ground

A patio near the creek bottom should sit a little above the yard. Build a compacted base of Road Base or Crushed Concrete over fabric, add a level bed of Concrete Sand, and lay the pavers with a gentle pitch away from the house. A gravel patio of #57 Crushed Stone or Pea Gravel over the same base drains even faster.^[1]

Plants that hate wet feet need raised beds here. Build them with Garden Soil or a mix of Topsoil and Compost, a few inches above the native loam. Cover them with Brown Shredded Mulch or Black Shredded Mulch, which mat together and do not float off as easily as loose chips in a flood.^[1]

Along a stream bank on your property, Riprap over fabric protects the soil from being cut away by fast water.^[1]

Rain gardens suit this kind of lot. A shallow, planted basin filled with a mix of Garden Soil and Compost catches runoff from a roof or a drive and lets it soak in slowly. On ground with a high water table, keep the basin shallow and place it where the yard is a little higher, so it can drain between storms.^[1]

Homes in ZIP 28078 and the North Carolina spec

The Census counts 28,874 housing units in ZIP 28078. Detached single-family houses make up 75 percent of them, the median build year is 2004, and owners live in 72 percent of the occupied homes. Huntersville as a whole has 25,913 housing units, also 75 percent detached, with the same median build year of 2004.^[5]

Many lots of that age have yards graded from mixed fill. Before a stone project, dig a test hole and look for layers. Gray or mottled soil near the surface is a sign of a high water table and a reason to raise the work.^[1],[5]

Shed pads and play areas follow the same rule on this ground. Build the pad up a little above the yard with #57 Crushed Stone over fabric, so water drains out of the stone instead of pooling under the floor. Under a swing set, Playground Sand or Wood Chips over a layer of open stone dry out faster after rain.^[1]

NCDOT, the North Carolina Department of Transportation, writes its standard for the stone layer under roads as Aggregate Base Course, Section 520, in the Standard Specifications for Roads and Structures (January 2024).^[6]