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.
Carter Road Detention Basin
Completed in 2004
The Carter Road Detention Basin is located in the northwest portion of the Bee Branch Watershed. An earthan dam approximately 350' long and 40' high was created to hold back stormwater and slowly release it to allow time for the downstream flood-prone area to drain.
The basin can hold 59.3 million gallons of stormwater runoff and is designed to reduce peak flow of runoff during a 100-year rain event by 98% from 1,490 cubic feet per second down to 30 cubic feet per second. The principal outlet of the dry bottom detention basin is a 15‐inch diameter culvert with a 24‐inch diameter gated culvert. The high flow outlet is a 48‐inch diameter riser pipe that is approximately 37‐feet high.
W. 32nd Street Detention Basin
Completed in 2009
The storage capacity of W. 32nd Street Detention Basin was more than doubled from 15 million gallons to 32 million gallons of water. A combination of wild flowers, prairie grass and wetland vegetation was planted to maximize its ability to retain runoff and reduce flows and volumes to downstream properties. The basin now provides the maximum amount of storage possible given the available land area.
The project required the acquisition of 16 properties, street and utility reconstruction to gain access to the storm sewer system, and installation of a gate structure for maintenance of the expanded basin's wet pond.