PoolQ I recently hired a pool contractor to build a residential pool. The contractor has been in business for more than 30 years and has a great reputation. The progress so far is that the pool has been installed using shotcrete. The shotcrete has been curing for the last 9 days. Within the last 9 days, it has rained heavily twice. On the second rainy day, immediately after the rain finished, I walked outside to see the amount of water that had collected inside the pool. I noticed that the water was muddy looking. Upon closer inspection, as the rest of the pool was dry, except for the deep end, there were two trails of water coming from the shallow end and running into the pool of water in the deep end. After getting down into the pool, I noticed that these trails of water were from water bubbling up through the shotcrete floor on the slope closer to the shallow end. The bubbling was like a small stream of water coming up out of the shotcrete in two places. I suppose it is from the hydrostatic pressure from the groundwater under the concrete? My question is should this be concerning? The plaster has not been installed. How should these holes be filled? The holes certainly do not look like they were intentional, as you can’t really even see them, except for the water coming out of them. Is there a problem with the shotcrete installation? Does this mean that my pool will leak when it is filled with water? I would image that if water can come up through the shotcrete, the water can also go down through the shotcrete, resulting in erosion of the soil under the pool? Before the shotcrete was installed, there was no groundwater present and the dirt was dry. (Referenced images can be found here)
It is difficult to make an assessment of a situation like this with a few photos and the description given. Based on your statement that the contractor has an excellent 30-year reputation, we’d suggest you discuss these concerns with the contractor. If his response does not give you a full explanation, we suggest you engage an independent professional familiar with shotcrete installations and swimming pools to give you an opinion. You can use ASA’s Buyers Guide at shotcrete.org to find a consultant.
There certainly is reason to question the quality of the installation based on the description. However, it is not unusual for the pool shell contractor to leave a temporary opening in the shell to relive potential groundwater pressure and prevent floating of the empty pool shell. These holes are, or should be done, in a professional manner to allow complete watertight sealing when filled. In some cases, the openings may include a pressure relief valve.
