#57 Limestone for Florida Drainage

Buyers mix this up with #67 and with drain rock more than any other stone in the yard, and the mix-up matters because the three do not behave the same in a wet trench. #57 Limestone is graded 3/16 inch to 1 inch, an angular crushed rock with the fines screened out. Nothing in it binds. That is the point of it: the gaps between the pieces stay open, and water uses them. #67 is the same idea at a slightly smaller size, drain rock is the catalogue name for the same open-graded role, and a graded mix with dust in it, whatever the label says, does the opposite job.

The perimeter drain is the job #57 limestone gets bought for here

On a flat sandy lot with the water table close to the surface, rain does not always soak away the way people expect. Flatwoods soils sit over a hardpan, and once that layer is wet the yard holds water at the surface for days after an afternoon storm. The standard fix is a trench that gives the water somewhere lower to go: a slotted pipe bedded in open stone, wrapped, and run out to daylight or to a dry well.

#57 is the size that suits it. Big enough that the void space between pieces is real, small enough to shovel into a narrow trench and work around a pipe without leaving a cavity. The same stone goes behind a retaining wall to keep water pressure off the back of it, under a slab as a capillary break, and into a concrete mix as the coarse aggregate.

How open stone behaves in flatwoods sand and a high wet-season water table

Open stone in sand has one enemy, which is sand. Fine quartz grains travel in moving water, and if they reach the voids they fill them, and a filled drain is a buried trench. That is why the wrap matters more here than it does on clay ground and why the trench gets designed around keeping sand out rather than getting water in.

The second thing to plan for is the wet-season water table. Between roughly late May and October the table rises, and a trench cut below it will stand full of water. That is not a failure, but it changes where the outfall has to be: a drain can only move water to somewhere lower than the water in it. Set the outfall first and work back to the trench depth, rather than the other way around.

Trench, fabric and pipe before the stone goes in

Cut the trench with a fall of about one percent toward the outfall, which is roughly an inch of drop every eight feet. Line it with a non-woven filter fabric, carried up both sides with enough overlap to fold over the top. Put two or three inches of stone in the bottom, lay the pipe on it with the slots down, then bring the stone up around and over the pipe. Fold the fabric across the top, then cap with a few inches of soil or with stone if you want the trench visible. A visible stone top drains faster; a soil cap is easier to mow.

Compaction is not part of this. Tamping open stone only breaks the edges off and closes the very voids you paid for. Settle it by hand and move on.

#57 against #67 and drain rock when the trench is narrow

The difference between #67 Stone and #57 is smaller than the price of getting the last row wrong. Open stone will not carry a pad, a shed or a drive, however hard it is tamped.

Yards for a 40-foot foundation drain, a soggy corner and a culvert apron

The calculator takes feet for length and width and inches for depth, handles up to five areas, and runs (L x W x D/12) / 27 = cubic yards before converting to tons by density. Three hypothetical examples:

• A French drain along a foundation, 40 ft long by 18 inches wide, stone 12 inches deep. 40 x 1.5 = 60 sq ft. 60 x 1 = 60 cubic feet. 60 / 27 = about 2.2 cubic yards, less the volume the pipe itself takes up.
• A soggy low corner turned into a stone infiltration pocket, 14 ft by 18 ft at 4 inches. 14 x 18 = 252 sq ft. 252 x (4/12) = 84 cubic feet. 84 / 27 = about 3.1 cubic yards.
• An apron at a culvert outlet, 8 ft by 10 ft at 6 inches. 8 x 10 = 80 sq ft. 80 x 0.5 = 40 cubic feet. 40 / 27 = about 1.5 cubic yards.

This site publishes #57 crushed stone at about 2,800 lb per cubic yard, roughly 1.40 tons per yard, so those three work out at approximately 3.1 tons (2.2 x 1.40), 4.3 tons (3.1 x 1.40) and 2.1 tons (1.5 x 1.40). Run those numbers through the stone calculator for the tonnage, since stone is ordered by weight. When you have a figure, choose a quantity and a delivery date here. Delivery is arranged at checkout by ZIP code, and the driver needs a clear route to a spot where the load can be tipped.