Drain Rock for Tennessee French Drains, Wall Backfill and Leach Fields

Most hill lots here get one wet winter's grace. The second year, water finds the same low corner of the crawl space or the same soft strip along the uphill side of the garage, and the answer is a trench. Drain rock is what goes in it: washed stone between three quarters of an inch and an inch and a half, with the dust taken out so the gaps between pieces stay open and water keeps moving through the layer rather than sitting in it.

The trench most of these orders get dug for

A perimeter run along the uphill side of a house or an outbuilding is the commonest job on this site's ground, closely followed by the strip behind a retaining wall. Both are the same idea. Water arriving downhill is intercepted before it reaches built work, dropped into a stone-filled trench, and taken to somewhere it can leave.

Leach field and septic construction is the other steady use, for the same reason: a bed of washed stone that holds its voids for the life of the field. The listing comes rounded or angular. Angular behind a wall, where backfill bears against the stone and the pieces need to hold their arrangement. Rounded where the stone stays visible.

How it behaves on cherty clay, karst ground and loess

Clay is the enemy of open stone, and there is plenty of it here. Cherty clay over limestone on the Highland Rim pumps upward into a stone layer under load, and the silt that comes off a bare slope in a summer downpour arrives from the other direction. Either one fills the voids and the trench quietly stops working.

Karst ground adds a second question. Across the Central Basin and the eastern valleys, sinkholes and openings in the limestone already take runoff underground, so a drain discharging toward ground like that wants thinking about before it is dug. Out west on loess, the outlet itself needs protecting, or the trench relocates the problem rather than solving it.

Fall, fabric and the outlet, in that order

Fall first. A drain that does not run downhill the whole way is a storage tank. Set a string line before anything is dug and check it again once the trench is open.

Fabric second. Woven permeable geotextile lines the trench, the stone goes inside it, and the fabric folds over the top before backfill. That envelope is the only thing standing between clean stone and cherty clay.

Outlet last, and it is the part people leave out. A trench needs somewhere to discharge that is lower than the lowest point of the run and stable enough not to scour. Daylight on a bank, a pop-up, or a ditch line. Without it, everything upstream is decoration.

One thing this stone should not be asked to do is line that ditch or armor a culvert outlet. Concentrated flow rolls washed three quarter to inch and a half pieces straight down the channel. Scour protection is a job for RipRap, sized for the flow, with this material kept to the trench behind it.

Drain rock beside #57 stone and 3/4 inch crushed

Three listings on this site will all drain a trench, and the differences are worth knowing.

Washed #57 stone runs a little smaller and is the usual pick in a narrow trench or anywhere a four inch perforated line has to be bedded neatly. 3/4" Crushed Stone is angular and clean at a single size, and it goes where the layer has to carry something as well as drain, such as a pad base.

This listing is the coarser of the three and the one for a job that is purely a water path: a deep perimeter trench, a wall chimney, a field bed. Bigger pieces mean bigger voids and more flow. The trade is that it is awkward to wheelbarrow and not something to bed a small pipe against.

A rock garden that doubles as a soak-away, and a shed pad that wants something else

A xeriscape or rock garden bed built over a low spot is a fair use of washed stone, because the bed drains what lands on it instead of holding it. Work it at about three inches over fabric. A 200 square foot bed is 200 x 3 = 600, divided by 12 = 50 cubic feet, divided by 27 = 1.85 cubic yards, roughly 2.6 tons. If the bed is purely for looks rather than for drainage, River Rock reads better at the same depth.

A shed or garage pad base is the one to hand off. Clean stone will not bind into a surface and a pad wants a material that compacts, which means Crusher Run or Dense Grade Base. This stone belongs there only as a drainage blanket under the pad on ground that stays wet, with the compacted base built over it.

Yards and tons for a 70 foot hill-lot drain

One hypothetical example, worked the way this site's calculator works: length by width by depth, divided by 27 for cubic yards. No weight is published for this listing on its own, so the figure below uses this site's closest listed family, crushed stone around three quarters of an inch at about 2,800 lb per cubic yard, roughly 1.4 tons to the yard, and it should be treated as approximate.

A perimeter run 70 feet long, 18 inches wide, with 18 inches of stone depth above the bedding: 70 x 1.5 x 1.5 = 157.5 cubic feet, divided by 27 = 5.8 cubic yards, about 8.2 tons.

For coverage on flatter work, a cubic yard is 27 cubic feet, so it spreads over about 81 square feet at four inches, 54 at six inches and 27 at a foot. Run your own trench through the stone calculator before ordering.

Booking a load and finding a drop the wheelbarrow can reach

Coarse washed stone is heavy to move by hand, so the drop spot matters more than usual. Put it as close to the open trench as the truck can safely get, on something firm, and lay a tarp under the pile so you are not raking stone out of the grass afterwards.

Delivery is arranged at checkout by ZIP code and the truck needs clear access to a place where it can tip, which the delivery notes explain. Have the trench open and the fabric ready before the load lands. Measure, work the yardage, then choose a quantity and a date here.