Guide

Materials, by the names the pits use

Order by the wrong name and you get the wrong rock. This is the working glossary of what Southcentral pits sell, what a yard of it weighs, and where it belongs.

Crushed and screened rock

The crushed list, as the pits sell it
ProductAlso calledWhat it isAbout per loose yardBelongs on
D-1Crushed base, base courseCrushed rock graded to the state spec, 1 inch down to fines, compacts hard1.4 tonsDriveway top course, pads, under pavers
3/4-inch minusThree-quarter crush, C-1Crushed to 3/4 inch with fines1.35 tonsWalkways, driveway topping, trench backfill
1.5-inch minusInch and a halfCoarser crush with fines1.35 tonsRural driveway top, sub-base
3-inch minusThree-inchScreened to 3 inches, fines included1.3 tonsSub-base, building up a lot, soft ground
Pit runType II, bank run, 4-inch minusUnscreened bank gravel as dug1.3 tonsDeep fill, the layer under everything
Sewer rock3-inch washed, filter rockWashed 2 to 3 inch, no fines1.25 tonsDrain fields, French drains, wall backfill
Septic rockInch-and-a-half washedClean 1.5 inch, no fines1.25 tonsSeptic drain fields to the design
Pea gravel3/8 minus, concrete peaSmall rounded or crushed, no fines1.3 tonsBedding, walkways, dog runs, concrete
Crushed rock, 1 inchDecorative crushAngular crushed, screened clean1.3 tonsLandscape beds, decorative surfaces

Weights are working figures; D-1 runs about 2,800 pounds to a loose yard and heavier once it is compacted in place. Moisture and how tight the loader packs the box move every number by ten percent either way. Order by the yard for volume jobs and by the ton for anything spec'd by a contractor.

Recycled material

NameWhat it isBelongs on
RAPRecycled asphalt pavement, milled and screenedDriveways and lots; packs hard and stays dark, dusty in July
RCCRecycled crushed concreteBase course and fill where a spec allows it, cheaper than virgin rock

RAP is the underrated driveway material in Anchorage. It compacts almost like asphalt once the sun has been on it, sheds water, and it is often cheaper than D-1 because the pits want it gone. It is not right under a slab and it will not pass a D-1 spec, but for a long rural driveway we would put it up against anything.

Soil and fill

NameWhat it isAbout per loose yardBelongs on
Screened topsoil with peatScreened native soil blended with peat1.0 tonLawns, beds, planting; the top 4 to 12 inches only
Unscreened topsoilNative topsoil with roots and rocks1.0 tonRough grade under a screened lift
PeatScreened peat0.6 to 0.8 tonAmending beds; never as fill
Clean fillSand or gravelly soil, no organics1.2 tonsRaising a lot, backfill, pads
Hardpan fillPit run with more fines, cheap1.3 tonsDeep fill where nothing will be built on it soon
SandWashed septic or fill sand1.25 tonsBedding, backfill, traction sand

Choosing between them

  • A driveway you will keep: strip organics, 6 inches or more of pit run or 3-inch minus, 4 inches of D-1 on top. The driveway cost page prices it.
  • A driveway on a budget: 3-inch minus base, 3/4 minus or RAP top. It will need a top-up every few years.
  • A shop pad: pit run to grade, D-1 the last 6 inches, compacted in lifts. The concrete crew will thank you.
  • Drainage: washed rock only. Fines in a French drain are how you build a dam.
  • A lawn: clean fill to grade, then 4 to 6 inches of screened topsoil. Not the other way around.
  • A wet lot: get above the water first with pit run; nothing placed in standing water compacts.

Reading a pit ticket

Every load we deliver comes with the pit ticket. It shows the pit, the product name as the pit sells it, the net weight or the yards, and the time. Keep it. It is how you know the 3/4 minus was 3/4 minus, how you reconcile our invoice, and how you answer the building inspector who asks what is under the slab.

Questions we get about this

What is the difference between D-1 and 3/4 minus?

Gradation. D-1 is graded to a spec with a controlled range of sizes so it locks under compaction; 3/4 minus is crushed to a top size with whatever fines the crusher makes. Both work on a driveway; only D-1 belongs under something you will pour or pave.

What does "minus" mean?

Everything smaller than the number. 3-inch minus is 3 inches and down, including the dust. "Washed" or "clean" means the fines were rinsed out.

How many yards is a ton?

For crushed gravel, about 0.7 yards per ton; for topsoil, about a yard per ton. The calculator converts for each material.

Which pit do you use?

The one that stocks the right material closest to your job. Anchorage Bowl jobs load in the Bowl; Valley jobs load Palmer or Wasilla side. The pit is on your ticket.

Sources

  1. Alaska DOT&PF, Standard Specifications for Highway Construction, 703-2.03 and Table 703-2 (D-1 base course gradation)
  2. Municipality of Anchorage code, footing depths and frost protection (Title 23)
Crafted in Anchorage, Alaska by Anchorage Web Design