Heavy rainfall can present problems for homeowners, and not just those in low-lying areas. A low spot in the yard, for instance, may become a temporary pond that can last for days, or the water can back up into a basement or home itself. A soak pit would alleviate such a problem, as it allows the water to drain from where it is unwanted to a storage area. This safely and gradually saturates back into the water table. Making a soak pit is labour intensive if you dig it by hand and shovel, but with a small backhoe you'll finish the digging in a few minutes.
Excavate a cube in the ground that's 3 feet to a side. Dig the hole away from the low, wet area and where there is little access to people. You may have to vary the pit size according to the available room and the type of soil you are working in.
Excavate a 1-foot-deep and six-inch-wide trench from the area with excessive water to the soak pit. The trench should slope 1/4 inch for every 10 feet in length to ensure the water drains toward the pit. The trench should end where the soak pit begins.
Cover the walls of the excavation so that the dirt does not fill inward to the pit. Options include using construction blocks or a cement crepe.
Stack the blocks on top of one another around the excavated area, making a four-sided chamber. You won't have to mortar together the blocks. Leave enough room between two of the blocks to allow access by the drain pipe. Fill in the space between the outside of the concrete blocks and the edges of the excavation with soil, and tamp it down.
Hand-tamp the dirt on the walls so it is solid and stable. Mix together 4 parts of cement, 1 part of sand and enough water to make a thin mixture like a pancake batter. Trowel this over the dirt walls of the pit in a thin layer, leaving an opening for the drain pipe. Let the crepe cement dry thoroughly.
Lay 6 inches of sand or gravel on the bottom of the pit. Precise measurements or levelling is not required.
Fill the soak pit with rocks of various sizes, taking care to not damage any crepe cement. Do not tightly pack the pit, which prevents water flow downward. The rocks should be of sufficient amount to keep the concrete block walls from pushing inward. The tops of the rocks should be just below where the drain pipe enters.
Fill the drainage trench with 2 inches of gravel, taking care that the downward sloping is protected.
Set a PVC drain pipe on the gravel, perforated side down. The pipe should extend into the centre of the pit. Fill the trench with soil and level it off slightly higher than the existing soil. The soil will settle downward.
Place a large, flat rock under the end of the pipe in the pit. This disburses the flow of water and prevents erosion of the rocks below.
Cover the top of the pit with a large sheet of metal or plywood. Place two or three concrete blocks or other heavy objects on the top of the cover to ensure a child does not inadvertently open the pit. Alternately, hide the pit by laying down several layers of plastic mulch and covering it with dirt. Plant grass seed or other shallow rooted plants on top of the pit. Mark the location so that you can find it again if needed.
Things you need
- Shovel or small backhoe
- Concrete blocks
- Hand tamper
- Rocks of various sizes
- 4-inch PVC drain pipe
- Pit cover
- Plastic mulch
- Grass or flower seed