Question: I recently read an article you answered back in 2019 concerning a homeowner’s concern about cracks in his sump pit wall.
I reside in a home where the water table is very high. My house, along with my neighbour’s house, have a constant discharge of water. As it sits now, the pump runs six to 10 times a day. My concern is that the walls of the pit appear to be bulging in and one of the weeping tile hoses has pulled away from the pit, allowing gravel and dirt to enter into the bottom of the sump. The house was built in 2014, on a footing, and is located in St. Adolphe. I was wondering what I should do about this, if anything?
Your feedback is greatly appreciated.
Answer: Deciding if anything is required to correct a buckled sump pit may be a difficult choice, even for an experienced inspector, homeowner, or contractor. As long as it is still functioning properly, not visibly cracked or damaged, and not causing any other issues, the situation may only require monitoring rather than immediate action.
Because of the expansive nature of our clay-based soil in the Red River valley, movement of house systems embedded in the soil is all too common. This may include foundations, basement floor slabs, plumbing drains and supply pipes, and sump pump and weeping tile systems. It may be impossible to completely guard against movement of these systems, but homebuilders will take measures to minimize this issue, at the time of construction. For weeping tile piping and sump pits, this normally includes surrounding these critical components with granular fill.
Most commonly used for this purpose is a building product called pea gravel. This easy to shovel material is made up of very small, round stones which provides a much more flexible substrate than the surrounding soil. Because the pebbles are round, they easily move against each other, even when under pressure. Also, the gaps between the numerous individual components allows for excellent drainage of water. These two properties make it an ideal material to bridge the gap between the clay soil and embedded drainage systems. This should be the gravel that you are seeing entering the sump through small gaps around the weeping tile piping.
While the pea gravel should provide a reasonable, flexible buffer between the plastic walls of your sump and the surrounding clay, it may not be completely effective in preventing excessive pressure on the pit. That may be due to a smaller than adequate amount of fill used, or some other factor. If there is constant moisture surrounding the sump area, due to poor grading or weeping tile leakage, then that may affect the structural integrity of the sump walls. If there is downward pressure on the basement floor slab near the pit, that may also cause the issue. Determining the true cause may not be possible without partial floor removal, which should not be necessary.
The plastic sump pit in your home serves only one function, which is to collect and contain water flowing from the weeping tile pipes, until the pump can successfully push that water back outside the foundation. This should be the case, as long as the walls of the pit are not cracked, or broken. Because the plastic is semi-flexible, it can bow and buckle a fair amount before that occurs. It is quite common to see this happen, and on rare occasions it will cause damage significant enough to warrant replacement. Unless that is the current situation in your home, even if the sump walls looked warped, there may be little concern.
The other consideration is the movement in the weeping tile pipes that terminate through the walls of the sump. These round, black plastic pipes have very large corrugations, which significantly increase their durability and strength. For that reason, it is very unusual for these to become damaged in uncut sections, even deep within expansive clay soils. But that property will not prevent them from moving lengthwise, if the soil surrounding them shifts, swells, or shrinks. For that reason, builders will normally extend these pipes several centimetres into the sump. The extra length should accommodate expansion and contraction of the pipes, as well as minimal to moderate soil movement. If this wasn’t done adequately, the pipes may pull back through the side walls of the sump, allowing pea gravel to spill into the pit. That situation will require remediation, because the weeping tile water may not be fully draining into the sump and an extension of the offending pipes will be needed.
Pre-emptive repairs to your buckled sump pit and weeping tile system may only be necessary if there is visible, physical damage, or if the water from the pipes is not fully entering the sump. If that is not the case then regular inspection and monitoring of the situation should alert you to any negative changes. If those do occur, replacement of the sump pit and/or repairs to the weeping tiles will be warranted.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and a Registered Home Inspector (RHI)(cahpi.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.