We're having a PCS automatic pool cover installed on our Minnesota 18x36 vinyl liner pool. It will be installed recessed under the concrete at the end of the pool where the diving board is. The installer was out the other day to mark the area where the concrete will be cut. After cutting the concrete, they will build a wood vault for the motor / mechanism. My concern is how close the concrete cut will be to the edge of the pool. Due to the location of the diving board, the wood vault that contains the mechanism will be set back only 5 inches from the edge of the pool. In other words, there will only be 5 inches between the wood vault and the water. The vault will be approx 15 inches below ground level. Will 5 inches between vault and edge of pool be enough to properly support the edge of the pool? Some of the documents I've seen state that there should be 12 inches between the edge of the pool and the vault, but my installer maintains there will be no issues. The last thing I want to do is affect the structural integrity of the pool. Is a 5 inch setback enough? Thanks!