Drain Rock in Wisconsin: Washed Stone for Trenches That Have to Keep Working

Most of the drains that get dug twice were built with the wrong stone the first time. A load of pit-run or crushed base looks right going into the trench, and it drains fine through the first autumn. Then two thaws go by, the dust and the fine sand settle into the gaps, and the water starts coming up in the same corner of the basement it always did. Drain rock is the material that avoids that: washed, coarse and graded so the empty space between the pieces is the thing you are actually buying.

The mistake is understandable, because on a Wisconsin site everything looks like gravel by the third load. The difference is in what has been washed out.

Washed, 3/4 to 1-1/2 inch, and nothing fine left in it

Spec summary, taken straight from the product listing:

• Size: 3/4 inch to 1-1/2 inch.
• Grading: washed to take out the fines and the dust.
• Type: supplied in rounded and angular varieties.
• The range matters as much as the top size. A spread of sizes between 3/4 and 1-1/2 inch keeps the pieces from nesting into one another, which is what keeps the voids open.
• Angular pieces hold their arrangement where backfill or a wall bears on them. Rounded pieces sit more kindly in a visible landscape drain where nothing is loading them.
• What the washing does not do is make the stone a filter. Fabric does that. The stone only stays open if something stops soil getting into it.

Which drainage job takes Drain Rock, and which one does not

Red clay, kettles and a thaw that arrives from the top

• On the Lake Superior red clay plain and the Lake Michigan and Green Bay clays, water cannot soak down at all while the subsoil is frozen. A trench there is not draining into the ground; it has to carry water somewhere and let it out.
• In the Kettle Moraine and the south-central glacial plains, kettles and low ground between drumlins collect meltwater, and tight till holds it near the surface. The outlet is the hard part of the design, not the stone.
• Central Sands outwash drains fast once thawed, so the risk flips: sand migrating up into the stone is what ends the drain, which makes the fabric wrap non-negotiable.
• In the Driftless Area, water runs off ridges fast and then disappears into cracks and springs. Trench routes there follow where the water actually goes.
• Footings sit at least 48 inches down under the Uniform Dwelling Code, and frost under pavement can reach 48 to 72 inches by late winter. A perimeter drain has to sit below the water it is meant to collect, not alongside it.

Tonnage for a fire ring, a pole barn drip line and a drive-edge drain

Length times width times depth in inches divided by 12, then divided by 27, gives cubic yards. The closest published figure on this site's calculators is crushed stone at about 2,800 lb per cubic yard, which is 1.40 tons per yard. Treat it as approximate for this product, because the washed 1-1/2 inch pieces sit slightly more openly than a 3/4 inch stone.

• Example, a fire pit surround, a 12 ft circle with a 5 ft fire ring in the middle, at 3 inches. Outer area 3.14 x 6 x 6 = 113 square feet, less the ring at 3.14 x 2.5 x 2.5 = 20 square feet, leaves 93 square feet. 93 x 0.25 = 23 cubic feet, divided by 27 = 0.86 cubic yards, times 1.40 = about 1.2 tons.
• Example, a drip line trench down the two long sides of a 40 ft by 60 ft pole barn, 12 inches wide and 18 inches deep: 120 ft x 1 x 1.5 = 180 cubic feet, divided by 27 = 6.7 cubic yards, times 1.40 = about 9.3 tons.
• Example, an edge drain along 60 ft of a single-car gravel drive, 10 inches wide and 24 inches deep: 60 x 0.83 x 2 = 100 cubic feet, divided by 27 = 3.7 cubic yards, times 1.40 = about 5.2 tons.

A cubic yard covers about 108 square feet at 3 inches. Trench work is easier to think about by the running foot: a 12 inch by 18 inch trench uses one and a half cubic feet for every foot of length, so 18 feet of it makes one cubic yard. The stone calculator will do the conversion if you would rather enter the measurements and read off the tons.

Clearing a dump spot before an April truck turns in

• Delivery is arranged at checkout from your ZIP code. Pick the drop point first, and make sure a loaded truck can get in and reverse out without crossing soft ground.
• Drop as close to the trench as the ground allows. Washed stone is heavy and every extra wheelbarrow run is paid for twice.
• On a soft spring yard, keep the truck on the drive and plan to wheelbarrow rather than have it rut the lawn getting closer.
• A tarp or a sheet of plywood under the pile keeps the stone clean and keeps your driveway unscuffed.
• Class II state highways and posted county, town and village roads carry spring weight limits while frost is coming out, so if the lane in is a posted town road, a later date may be the simpler plan.
• Have the trench dug, the fall checked with a string line and the fabric on site before the load lands. Stone sitting on the drive for two weeks is stone you will move twice.

Work out the tonnage, then pick a quantity and a delivery date on this page, or send the trench measurements through the contact form if the run bends and you want the figures checked first.