Crusher Run in Pennsylvania: 3/4 Inch Minus That Packs Tight

Across the glaciated corners of the state, a foot or two under the grass there is often a dense layer of till that water will not pass through. From fall into late spring it perches whatever falls on the ground right there, which is why a low spot in a Northern Tier yard stays a bog in May while the ridge above it has dried out. Crusher run is one of the two materials people bring in to fix ground like that, and knowing which of the two you actually want is worth five minutes before you order.

Gray dust and sharp chips: reading a load of crusher run

Tip a bucket of it out and you get angular crushed stone topping out around three quarters of an inch, mixed all the way down through chips and grit into stone dust. Nothing is washed out of it. Roll a damp handful between your palms and it takes a shape and holds it. That behavior is the product: the sharp faces of the larger stone wedge against each other, the dust fills what is left, and once it is wetted and rolled the layer stops behaving like loose stone and starts behaving like a slab.

Compare it against a shovel of 2B Stone, which is the same nominal size with the fines washed away. That one pours, rattles and never sets up. Both have their place. They are not interchangeable in either direction.

The regrade that puts most of these orders on a truck

The job this material is bought for most around here is not a highway. It is a low spot. A yard that ponds after every thaw, an old equipment yard being brought back to grade, a pad for a shed or a hot tub that has to come out dead level and stay there. Crusher run gets spread into the hollow in lifts, wetted and compacted, and the ground comes back up firm rather than soft.

Two related jobs on the assignment list are worth naming because they go the other way. A French drain along a foundation should never be backfilled with this. A ditch line or a culvert outlet should not be lined with it either. Both of those are covered further down, along with what to order instead.

Stony till, perched water and what that does to a compacted layer

The glaciated northeast and northwest sit on stony till over shale, siltstone and sandstone, with sand and gravel filling many of the valleys. Long cold winters put the ground through freeze-thaw cycle after cycle, and soil that stays wet above the dense till layer heaves under a thin base.

That gives a compacted layer a two-sided problem. It has to be thick enough to spread the load, and it has to sit on ground that drains, because the fines that make it strong are the same fines that turn it to pudding when water cannot get away. Cut the layer into a crowned shape so surface water runs off rather than soaks in. Give the low side somewhere to go. On ground that is genuinely wet, sort the drainage before the stone arrives, not after.

Laying it in lifts before the ground goes soft again

Snow and wet, soft ground can hang around well into spring up here, so the working season starts when the ground has thawed and drained and runs into fall. Stone does not go down on frozen or muddy ground; a layer laid over frost is a layer that settles unevenly the week it thaws.

The sequence that works: strip sod and anything organic, fix the grade, then place the stone in lifts rather than in one deep dump. Each lift gets damp, not soaked, and gets rolled or plate-compacted until the surface stops moving under the machine. Compacting a deep layer in one pass leaves the bottom half loose, and the bottom half is the part doing the work.

Where 2A Modified and 2B Stone take the job instead

2A Modified is the default here. It is the dense-graded base Pennsylvania yards, contractors and municipal specs talk in, sized one inch minus with binding fines, and if you ask a local outfit for base stone that is usually what you get. If your job is a drive, a lane or an equipment pad and you want the material the trade around you is describing, order that one. Crusher Run is the three-quarter-inch minus equivalent, and it suits tighter work: shed pads, patio bases, smaller pours where a one-inch top size is coarser than you want.

2B Stone is the other direction entirely. Clean, washed, no fines, open voids. Foundation drains, curtain drains, wall backfill and anywhere water has to move through the stone rather than around it. #57 Stone covers the same ground under the AASHTO name. For a ditch line or the apron below a culvert, neither of these is heavy enough, and RipRap is what holds against moving water.

Cubic yards for a low spot, a drain trench and a ditch line

Hypothetical examples, worked the same way each time: square feet, times depth in feet, divided by 27.

Odd shapes are the same job done twice. Break the area into rectangles, triangles and part-circles, work each one out, and add the results. A triangle is base times height divided by two. At the weight published on this site's calculator pages for crusher run and road base, about 3,000 lb per cubic yard or roughly 1.50 tons per yard, the low spot works out at 6.1 x 1.50, approximately 9.2 tons. Everything is bought by weight, so put your cubic yards through the crusher run calculator for the tonnage, and leave its 10 percent allowance ticked where the stone is going to be compacted.

Choosing a date and a drop spot on a narrow lane

Set the quantity and the delivery date on this page once the arithmetic is done. Delivery is arranged at checkout by ZIP code, and the truck needs clear access to a dump spot with room to back out of it. On a soft spring lane that means picking a firm place near the work rather than the closest place to it. If the gate is tight or the grade is awkward, send the details through Contact before you book the date.