#4 Crushed Stone in Maryland: The Size You Reach For When the Ground Gives

There is a stretch of lane on a lot of Maryland properties that behaves differently from the rest of it. On the Coastal Plain it is where sand gives way to a clay lens and the tractor sinks; in the Piedmont it is the dip where silt loam stays wet a week after everyone else has dried out; in the limestone country west of Frederick it is the low spot that reappears every spring. Ordinary base blends disappear into ground like that. Stone the size of a fist does not, and that is the entire argument for this product.

#4 next to #57, CR-6 and ballast: four stones that look interchangeable

Grading: #4. Type: angular crushed stone. Approximate weight, from this site's own published figures for #4 stone and ballast, about 2,900 lb per cubic yard, or 1.45 tons per cubic yard.

The useful distinction is between clean and dense-graded. CR-6 has fines in it, which is why it binds and why it will also turn to paste when it is worked into wet clay. #4 has no fines to lose. It bridges rather than binds, and it keeps draining while it does it.

Farm lanes, construction entrances and gabion baskets on wet Maryland ground

• The soft section of a farm lane or rural access track, where the stone is placed deep enough to bridge the weak ground rather than sink into it.
• A construction entrance off a county road, where coarse stone shakes mud off tires before they reach the pavement.
• The bottom course under a drive on saturated Piedmont clay, with a finer base and then a surface course above.
• Slope, swale and ditch protection where runoff is cutting, and the angular pieces are heavy enough to stay where they are put.
• Gabion baskets and similar retaining assemblies, where the size suits the mesh.

The garden path and the new lawn that want a different truck

Two jobs come up often enough on this page to be worth heading off. A garden path built in #4 is unwalkable. Stones this size turn an ankle, never knit, and swallow a wheelbarrow wheel. Path volume, as a worked example: 40 feet by 3 feet at 3 inches is 120 square feet, 120 x 0.25 = 30 cubic feet, divided by 27 = 1.11 cubic yards. Take that figure to Walkway Gravel or 3/8" Natural Pea Gravel.

New lawn prep is not a stone job at all. As a worked example, a 1,800 square foot area at 3 inches is 1,800 x 0.25 = 450 cubic feet, divided by 27 = 16.7 cubic yards. At the site's figure of about 2,200 lb per cubic yard for screened soil, that is roughly 18.3 tons of Top Soil. Where the grade also has to come up, fill dirt goes underneath and the topsoil caps it.

How deep #4 goes, and what has to sit on top of it

This stone is a bottom course. The depth it wants depends on how bad the ground is rather than on what will drive over it, and it always has something finer above it before anything is finished.

• On soft, saturated ground, place it deep enough that the layer spans the weak spot instead of being pushed into it, and put a separation fabric under it so the stone and the mud do not become one material.
• On Western Maryland slopes, where snowmelt and rain funnel into narrow valleys, get the water across or around the lane first. Stone laid in a running channel is stone you will buy twice.
• Across the Piedmont, frost reaches about 30 inches in most county codes, 36 in Garrett and Allegany, and 24 in several Eastern Shore counties. Water trapped in a base through a freeze is what heaves the surface above, which is the case for a bottom course with open voids.
• Above it goes a compacted dense-graded layer, then a wearing course of driveway gravel. Left exposed, #4 stays loose for ever and sheds stone to the verges.

Tonnage for a 300-foot lane outside Sudlersville, and what to have ready

Square feet times depth in feet gives cubic feet; divide by 27 for cubic yards; multiply by 1.45 for tons. A worked example, not a real job: a lane 300 feet long and 10 feet wide, taking a 6 inch bottom course over its worst run. 300 x 10 = 3,000 square feet. 6 inches is 0.5 feet, so 3,000 x 0.5 = 1,500 cubic feet. 1,500 divided by 27 = 55.6 cubic yards, which at 1.45 tons per cubic yard is about 80.6 tons, call it 81.

A lane that only needs its worst 90 feet treated scales straight down: 90 x 10 x 0.5 = 450 cubic feet, 16.7 cubic yards, about 24 tons. Run your own measurements through the stone calculator rather than scaling by eye, and measure the width where the lane is widest.

Delivery is arranged at checkout from your ZIP code, and a load of this size needs a spot the truck can reach, tip and reverse out of with firm ground under the wheels. That last part matters more here than on most orders, because the reason you are buying #4 is that some of your ground will not hold a truck. Flag the drop point away from the soft section. Then pick an amount and a date on this page, or send the lane dimensions through contact if you would rather have the figure checked first.