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Sump pumps are used with a sump pit to remove unwanted water from residential areas such as basements and crawl spaces. Sump pits require a liner to prevent the erosion of dirt and to prevent debris from clogging the pump. These liners can be made of something as simple as a 5-gallon bucket buried in the ground. There are any number of plastic/rubber commercial liners available. For a more permanent and solid solution, a concrete pit liner can be constructed.
Dig out the area for the sump pit. An ideal size for a sump pit is 30 inches by 30 inches. If your area will not allow this a pit 18 inches across and 30 inches deep is acceptable. Since you will be pouring concrete sides and bottom, add 3.5 inches to the depth and 7 inches to the overall width. Dig the pit using the shovel, making certain the sides are as level and straight as possible. The base of the pit will also need to be as level as possible.
Build the forms to hold your concrete. Build a square wooden box 30 inches tall and the desired width of your sump pit. Plywood braced by 2-by-4s and assembled with screws works very well. Screws work better than nails. Screws are far easier to remove when you want to disassemble the frame without damaging your pit liner. When completed the box should be 7 inches narrower than your raw pit and 3 inches shorter.
Secure two 2-by-4s across the top of the frame. These boards need to be a minimum of two feet longer than the overall width of the raw pit. Lower the frame into the pit, allowing it to be supported by the two 2-by-4s as they rest on the floor or ground. Center the frame in the pit by carefully measuring from all four sides. The base of the frame should be 3.5 inches above the bottom of the pit. This will allow you to pour the base and sides in one continuous piece and eliminate any seams which could result in seepage.
Mix the cement in the wheelbarrow. Add enough water to completely mix the cement, but allow the mixture to remain more firm and watery. Thoroughly mix the concrete for best results. Carefully poor or scoop the cement into the bottom of the pit until it reaches the bottom of the frame. Pour an additional amount around each side of the frame to a depth of 2 to 3 inches. Allow this to harden slightly, waiting 30 to 45 minutes before adding more concrete.
Add more concrete around the sides of the form until the cement is level with the upper edges and floor of the basement/cellar. Use the hammer to firmly tap on the inside of the frame. Move up and down all four sides of the frame. This will help remove air bubbles in the concrete and give you a smoother finish. Use the trowel to smooth the top of the cement around the frame.
Disassemble the frame by removing the screws. This can be done approximately 24 hours after pouring the concrete. Remove the frame piece by piece to avoid damaging the pit walls. Once the frame is removed, allow the pit to harden for several days before completing the installation of the sump pump and other components.
- For added strength you can add rebar or metal fencing around the frame before pouring the concrete. In most instances this extra strength is not required.
- Check the location of any underground utilities in your home. You will want to know the exact location of any gas lines, water supply lines or sewer lines before digging.
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