The Melvina Ditch Reservoir was constructed in 1965 based on 1960s rainfall data. In 2013 and 2014, the reservoir filled to capacity, highlighting the need to increase stormwater storage and to manage more intense rainfall events. Our water engineering experts were selected by the MWRD of Greater Chicago to help reduce the area’s flooding risk by increasing the reservoir’s holding capacity and retrofitting the pumping station.

KEY CONTRIBUTIONS:

Stormwater Management Design
We provided creative engineering and technology solutions to reduce the problems, including vertical expansion of the reservoir by digging an additional 10 feet of depth and retrofitting the existing pump station, which minimized the horizontal expansion footprint and created cost effective storage solutions in this urbanized community with limited open space.

Hydrologic & Hydraulic Analysis
The watershed modeling was completed in XP-SWMM to evaluate the complex flow between surface conveyance throughout the streets and sub-surface flow through the large diameter storm sewers. This allowed us to evaluate timing differences through the watershed and between the two existing reservoirs to fully evaluate system opportunities and constraints.

Pump Station Retrofit
We identified pump inefficiencies during peak storm events. We recommended constructing an emergency overflow spillway with a capacity equal to the pump capacity to allow discharge from the reservoir during power failures. Pump improvements were also recommended to reduce the inefficiencies.