septic tank pump

2 sump pumps can be better than 1

Q:

Our house was built in 1998, and we have been the only owners. The foundation walls are poured concrete, not block. There is a full basement under everything but the garage portion of the house. We have had three instances of water in the basement in the 17 years that we have lived here. All three were during or right after periods of unusually heavy storms that were bad enough to cause flooding throughout our entire area. In all three cases, there does not seem to be one specific point where the water comes in. I believe that it's percolating up evenly through cracks in the floor slab when the water table rises. During the second event in 2009, we had roughly 2 inches of water in the basement. At that time, I contacted our builder and asked where he had run the French drains. He told me that due to the fact that the lot is fairly level and with the French drains roughly 6 feet below finished grade, he could not slope the French drains to daylight so he took them out into the backyard and turned them down into a gravel pit. At that point, I had a sump pump installed in a corner of the basement. The output of the pump is tied into a downspout takeaway that goes out to daylight at the curb. The pump is rated 70 gallons per minute and includes a battery backup secondary pump. I have had to replace the pump once in 2013. In general, I would say that it has functioned well. Event No. 3 was during a particularly heavy rainstorm. We ended up with enough water in the basement to soak the carpet that is glued to the floor. There was not any standing water but the wetness was uniform throughout the entire basement. The water was clear. At the peak of this storm, I uncovered the sump pit and saw that the sump pump was running flat out and the backup battery was fully discharged, so I'm guessing that throughout the night, the main pump could not keep up and the battery backup was trying to add to the output, but probably could not push into the head created by the volume being carried away by the main pump. I also did not see any obvious grading deficiencies that would direct water toward the house. I even crawled under the deck that you see in these photos to check that the grading there was not sloped toward the house. I'm fairly convinced that during periods of unusually heavy rains, the water table on my lot rises to the point where it comes up through the basement floor. With the French drains not plumbed to daylight or to a storm sewer, I expect that they can become ineffective as the water table rises. My immediate next step is to put in a sump pump with an increased gpm rating. Long term, I'd like to find a way to get more of the ground water carried away from the property - possibly tied into storm sewers that run down both the road in the front of the house and the road in the back of the house. There is a floor drain in the laundry room, near the sump pump. Would it be possible and within code to tie the existing under slab drainage into that floor drain?

A:

There may be a problem with the large stone patio/walk, as water penetrates between the stones' joints, unless the stones were set on a concrete slab. The planting and mulched bed on one side of the house can also trap water and prevent it from draining away on the lawn. The joint of the lawn and the bed forms somewhat of a dam that catches and retains any surface water. The same situation may exist on the front of the house where there is extensive planting. But this does not mean that your conclusion that the water is coming through cracks in the floor is not valid. Where accessible, you may want to work some water seal compound into the cracks; it might help. It is not uncommon for the water table to rise, or an underground spring to swell, after a heavy downpour. And this may be the problem. In this case, installing an additional sump pump with a much higher discharge capacity may be a better answer than replacing the existing pump. Zoeller makes excellent, reliable pumps, which I have used extensively during my active contracting days. You can browse Zoeller's website, www.zoellerpumps.com, and find pumps with a capacity of well over 100 gpm. The fact that the sump pump discharge is tied to one of the downspout pipes may also be a problem, as that pipe may not be able to handle both the roof water and the sump discharge in unusually heavy downpours. The two sump pumps' discharge should be piped separately. As to tying the laundry room floor drain into one of the storm sewers, this must be dealt with according to your locality's regulations.