Sump pumps are used to remove ground or runoff water from areas such as basements or crawl spaces. These pumps are installed in a sump pump pit which acts as a collect point until enough water is collected and the pump is activated. There are a large number of commercial pit liners available, but in many instances it is more desired to construct a concrete pit liner rather than to install a plastic liner in your cement floor. This process is fairly straight forward and can be completed in a weekend.
Mark out the area for the sump pump pit. If you will need to cut through the basement floor be certain to double check all measurements before starting work. You will also need to check the routing of all water and utility lines coming into your home. You do not want to be digging into your water main of gas supply line after having cut a hole in your floor. Proper planning and preparation are the keys to a successful project.
Cut out the area of concrete using a skill saw and masonry blade. Cut the hole six inches wider than the planned interior size of the sump pit. A sump pit should be between 18 and 30 inches wide. Remove all concrete from the area and then begin removing the soil. Dig down to a depth of 39 inches from the basement floor. Keep the walls of the pit straight and neat, being certain to remove any large rocks root or other debris you may encounter. Once the hole is dug you are ready to assemble your frame.
The frame should be constructed of 2 by 4’s and plywood. Use screws to assemble the frame. This will make it far easier to dis-assemble the frame later without damaging the pit liner walls. Construct the frame in a square 30 inches high and six inches narrower than the pit you have just excavated. Be certain the frame is square and sturdy. Atop the frame lay two 2 by 4’s which are 24 inches longer than the pit is wide. The boards will support the frame in the pit while you pour the concrete.
Pour a six inch layer of gravel in the base of the pit. Rake it smooth, then carefully set the frame in place. Center the frame so there is a three inch opening on all sides. The boards across the top of the frame should hole the frame three inches above the gravel at the base of the pit. Use weights of some kind on the two supporting boards to insure the frame does not move.
Mix concrete in a wheelbarrow and slowly pour enough into the pit to form the bottom of the pit. Smooth and level the bottom of the pit with a trowel, then allow this to sit for 30 minutes to an hour, then pour the cement around the frame to form the walls of the pit. Work the wet cement with a shovel or pole to help remove any air bubbles. Continue to add cement until the pit walls are level with the basement floor. Smooth the top and allow the concrete to set for a minimum of 24 hours before removing the frame. The pit is now ready to have the sump pump installed and be put into service protecting your home.