The purpose of the detention basins is to hold back stormwater to allow time for the downstream flood‐prone area to drain. The construction of the new Carter Road Detention Basin, in conjunction with the expansion of the West 32nd Street Detention Basin, detains stormwater to the extent that the existing downstream Bee Branch storm sewer is capable of handling the peak flood flows from 32nd Street to 24th Street.
Prior to expansion, floodwaters would overwhelm the downstream storm sewer, rise over top of the basin, and result in a wall of water flowing through the City’s North End contributing to the street and basement flooding. As a result of the improvements, the peak flow of runoff out of the West 32nd Street Detention Basin is reduced to 30% of the peak flow into the basin and downstream flooding has been slightly reduced.