Basement Flooding: Plumbing, Decisions, Decisions
As we formed a plan of attack on this family’s basement flooding issues, we came to the conclusion that this was not going to be an inexpensive fix. We decided we would go as far as we felt we could go without getting into structural issues regarding the foundation. We decided to start at the sump pit and move out from there. We know that the sump pump, sump pit and discharge piping all have a build –up of the aforementioned substance, there is no way to clean it out or dissolve the substance adequately so we decided the customer needed to have that completely removed and re-installed with new equipment and piping. Easy so far, right? We didn’t think there was an accurate way to gauge how much drain tile was blocked so we decided to remove the entire interior system. Believe us when we say this was not a decision reached lightly, this was a 3K square foot ranch, and its footprint was large however it wouldn’t have been cost effective to sawcut the basement floor in 2ft sections.
Plan Twice, Cut Once
We have a saying in the trades, “measure twice cut once” this is pretty self explanatory but we wanted to apply it in this situation as well. Let us preface this by saying that we gathered the information we had and gave the customer a hard dollar amount as to what the repairs would cost. We decided to saw cut the basement floor around the inside perimeter of the basement floor 18” wide. This gave us enough space to remove the existing drain tile. Because we had a good idea that the substance was leeching into the drain tile from the existing soil we decided to excavate down 2ft and refill with clean pea gravel. Our idea was that if we removed enough contaminated soil and replaced with clean fill we would greatly diminish the chances of this problem returning. We knew we were going to remove corrugated drain tile but we weren’t keen on replacing it with the same. Perforated green sewer and drain pipe with a filter sock is what was decided we would use because it is rigid and smooth. The reason for using this material is if the problem ever reoccurred we could camera and locate the blockage. To further facilitate maintenance we installed three (3) cleanouts in the corners of the foundation and two (2) more where the foundation wall makes a change of direction. Doing this allows us to rod, hydro-jet or camera from almost any place in the basement.
Our first order of business was to bring in a professional concrete sawcutter to go over logistics. A professional sawcutter can cut the concrete in sections as large or small as a customer requests, however with concrete weight is an important thing to consider. When putting together the plan we had to ask ourselves “how are we going to get the concrete and excess spoils out of the basement?” Luckily the house wasn’t very old and was built with an escape window well. This allowed us to set up a conveyor belt system to shuttle the excess material out of the basement. The sawcutter cut the pieces in 1.5ft x 2ft pieces. We also made sure the saw used had a vacuum set up to limit the dust and to suck up the concrete slurry left behind by the saw.
We constructed the conveyor, the sawcutter began cutting and flipping the concrete and after enough of the floor was removed we began excavating the drain tile. To say that we were surprised by what we found is an understatement. At each window well and extending out from there the drain tile was packed solid with clay like sludge. When we were finished excavating just the drain tile we had removed over a yard of sludge, it was so heavy we had to cut it up into sections. After completely removing the contaminated spoils we had filled up almost an entire 5 yard container.
*Please note, if someone is inclined to self perform this repair please make sure to use an electric saw for your sawcutting. Have the windows open is not adequate ventilation for a gas saw.
O.K. so we removed all of the concrete, spoils and all of the drain tile, put down a pea gravel bed, installed the new drain tile and backfilled with pea gravel. The last thing we had to do was patch the concrete. We again had to think about logistics, how do we get the concrete into the basement? We could do two different things, mix all the concrete in the basement with small mixers or mix everything outside, build a shoot and pour it through the escape window well. We decided to do the later because we were concerned about being able to mix the concrete fast enough for a good pour. Here are a couple of things to do to prepare the open trench for the concrete pour. If you pour the trench with nothing for the new concrete to adhere to your run the very real possibility of the new concrete sinking so we pinned the concrete. We drilled drop in anchors into the concrete inside the trench and screwed in 8” pieces of all thread rod into the anchors. Finally we put wire mesh in the concrete to give it more strength.
After hooking up the sump pump, discharge piping and check valve, we ran water into the window wells and sump pit and all was working without a hitch.