Gravel Delivery FAQ: Camp Roads, Ledge and Mud Season

Most people land here with the same job in front of them: a drive or a camp road that came out of the thaw worse than it went in, and a decision to make about how much stone it needs. The questions below run in roughly the order they tend to get asked, starting with the two that cause the most trouble.

Where the yardage trips people up

Going from 3 inches to 6 on a camp road, what happens to the area one yard covers?

A cubic yard is twenty-seven cubic feet, so the coverage depends entirely on the depth you spread it at. At 3 inches one yard covers about 108 sq ft, and that is the figure worth carrying in your head on a camp road. The arithmetic is 27 divided by the depth in feet: at 3 inches, 27 ÷ 0.25 gives 108. Double the depth and you halve the coverage, every time, and the calculators will run any other depth and hand you the tonnage with it.

Item numbers and a short building season

What do NHDOT Item 304.2 and 304.3 mean when I am buying?

They are how base material is specified on a plan sheet in this state. Item 304.2 is gravel and Item 304.3 is crushed gravel, the common base course under drives and roads.

Treat them as a description of the material, not as a certification held by a storefront. If an engineer or a road agent has written an item number on your plan, compare it against the size and grading printed on the crushed gravel page, then confirm with whoever wrote the spec.

When in the year is the right time to build this?

Base, driveway and paver work runs from the end of mud season into late fall. Frozen ground will not compact, and ground that is thawing holds water above soil that is still frozen, which is how a load of stone disappears into a lane in April.

Higher up, the window opens later and closes earlier. Mud season in the White Mountains and the North Country runs behind the southern towns, so a date that works in one part of the state is early in another.

Drainage and bank work are the exception. They are best finished before the thaw that will test them, not after.

When the job needs an engineered answer

Who do I ask when the job needs a real engineered answer?

The town building official sets footing depth, and that is the answer on anything structural. An engineer belongs on a retaining wall of any height, on armoring a stream bank or shoreline where water is actively moving, and on drainage that has to leave your property in a defined way.

A material list is not a design. This site can tell you a size, a grading and a weight. It cannot tell you what a bank on a moving watercourse needs.

Stone that drains against stone that packs

Which stone is for drainage and which is for a base?

Fines are the whole difference. Stone with fines in it locks together and packs; stone washed clean of fines leaves voids for water.

• Packing: crushed gravel, crusher run and stone dust under flatwork.
• Draining: #57 stone, #67 stone, 3/4 inch crushed stone and drain rock.

Swapping them is the commonest material mistake here. Stone dust in a French drain silts up; clean stone under a shed pad never stops rolling.

Can screened loam do the work of fill dirt in a low spot?

No, and treating them as one material is the fastest way to over-order.

Screened loam, which is what topsoil is called here, is the top four to six inches under seed or sod. Garden soil is blended and lighter, for raised beds and planting holes. Fill dirt builds bulk in a low spot or under a raised grade, and gets capped with loam at the end.

Filling eighteen inches of low ground entirely with loam works, in the sense that grass will grow. It also buys expensive material to do a job fill dirt does.

Ledge, valley sand and what sits under the stone

Does till, ledge or river-valley sand change which material I pick?

It does, and more than the catalogue suggests.

• Stony till with granite ledge near grade: you will hit rock before the depth you planned. Build up instead, and grade the edges hard so water leaves.
• Sand and gravel outwash in the river valleys: forgiving ground that drains on its own, where a thinner section usually holds.
• Marine silt and clay in the Seacoast lowlands: slow draining and slow to dry in spring, so drainage comes before depth.
• Sand plains around the Lakes Region: quick draining, but runoff from sloped lots heads for the water, which is a reason to catch it.

Should I be putting geotextile down before the stone?

Where stone meets soft, fine-grained soil, yes. A separation fabric keeps the two from mixing, which is what actually makes a base disappear into a wet lane over a couple of seasons. It is also standard under riprap on a bank.

Where the subgrade is sound and drains, it adds nothing structural. And fabric is not a drainage fix: if water is arriving from uphill, it needs ditching or a cross culvert, not a sheet of geotextile. It is not a catalogue item here either, so it comes from a local landscape supplier.

Rounding, an area that is not a neat rectangle and the sum that turns feet and inches into tons all sit in the calculators. What the driver needs to find, and what gets chosen at checkout, are on the delivery page. Anything still unresolved can go to New Hampshire Rock Supply from the contact page, with your measurements and a ZIP code attached.

When in the year should this job be built?

Who operates New Hampshire Rock Supply?