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Old 12-10-2011, 06:53 AM
Senior MemberCaptains Club MemberPLEDGER
Join Date: Feb 2001
Location: Arlington, VA
Posts: 4,290
Received 146 Likes on 56 Posts

As for pumps, you can go overboard and treat it like a boat, which is what I did. Here's a cut and paste from a description I posted someplace else (for non-boaters):

We have a french drain around the entire basement perimeter connected to a sump in the front corner. In the sump are two 3500 gph pumps. A normal sump pump is in the 500 gph range. They're 12 volt dc bilge pumps, normally used for boats. Each pump has its own solid-state switch. Solid state switches are impervious to mechanical failures or hangups with debris. One switch is mounted higher than the other, so the second/backup pump only comes on when the first/primary pump fails or is overwhelmed. Each pump has a separate discharge out the side of the house. Both discharges have one-way valves to prevent backflow from outside water. The discharge from the primary pump is routed to the street through a 4" corrugated hose we buried under the front lawn. The discharge from the backup pump dumps into the side yard. If we're ever to the point where the backup pump is running, we don't care where the water ends up as long as it's not in the basement. There is a sealed agm group 27 deep cycle battery connected to each pump. Both batteries are connected to a charger which is then plugged into the wall. In this way, the pumps use house power when it's available and fall back to battery power when required. Each battery lasts for about four hours of continuous pumping and several days of once-per-minute pumping. The batteries, charger, and electrical outlet are all mounted high up off the floor to prevent any issues if water does make it into the basement. The wires between the pumps, batteries, and charger are long enough that the batteries can be moved to the floor or shelf as needed. All wire is tinned multi-strand copper and all connections are crimped and covered with adhesive-lined heatshrink to avoid corrosion and failures for many, many years. In addition to all this pumping capacity, we have also installed a one-way valve on the main sewer drain to prevent the type of storm/sewer water backflow that flooded us in september. We've also taken special efforts with carpet and other finishing elements to be as water and mold proof/resistant as possible.

Edit: The rains from tropical storm Lee in September caused a flash flood in our neighborhood. Water backflowed through a floor drain in our basement, but it was halfway up the windows outside. That means about 7' above floor level inside. Total water was above my knees and I'm 6'2". Even an inch or two in 24 hours causes our pumps to run.