I want to install a new 18 x 30 inch sump basin in our crawlspace. The old basin was a temporary means to pump out water while we determined the source of the water infiltrating our crawlspace. At the same time we also installed a concrete gutter on top of the spread footing for the front retaining wall. The gutter emptied into the old basin through a drainpipe in the gutter. We believed water may have been entering through the front retaining wall, but determined after watching two winter rains that was not the case. Ultimately we determined that all the water entering our crawlspace was coming through stake cavity openings in a wall we share with our neighbor. We have done everything we can to make sure we donÂt have water infiltration in the future, but there is always the possibility it will happen again if the downspouts for the townhomes upslope from us clog again and flood those crawlspaces.

The details are as follows. The bottom of the excavation for the new basin is below the base of all the foundation members surrounding it, but the base of the basin excavation does not bisect any 45-degree lines projected out from the bases of all the foundation members. Surrounding the top of the basin I want to install a 48 x 80 inch concrete apron.

The new basin is a Jackel SF30 PR made from structural foam and is very strong. I would like to set it in a three-inch base of sand to level it and then pour 4-inches of concrete around it up to 6-1/2" below the top of the basin. Let the concrete set up for a week and come back and pour a 48 x 80 inch concrete apron around it that allows surface water to drain into the basin.

The entire crawlspace has been graded to direct water to the basin location and the existing concrete gutter will be modified to remove the pipe that drained into the old basin and the lip will be removed so any water entering the gutter will drain into the new basin.

The purpose for this basin is just for removing water that may enter the crawlspace due to the possibility of downspouts clogging up slope from us. We do not have a problem with raising groundwater and do not want to install a basin that will allow groundwater to enter below the grade of the crawlspace.

My main concern is to maintain the soil bearing around the foundation and minimize soil heave under the basin and apron. I would appreciate comments from anyone who has a background pertaining to this type of installation and welcome suggestions.

Thank you for taking the time to read my post.

Howard