GE Aviation has operated a facility in Evendale, Ohio since the late 1940’s, but the site itself has been in use since July of 1940 producing aircraft engines. More recently, the 430 acre site has experienced flooding on multiple occasions that have required the facility to cease operations to allow for flood waters to recede and for cleanup of the flooded areas to be completed. CDM was retained to study and determine the capacity of the existing drainage system within the facility as well as generate potential alternatives for improvement to the storm drainage of the facility if they are necessary. Flooding conditions within the facility are thought to be exacerbated by a high ground water table within the limits of the site that have in the past caused flooding of basement areas within the buildings.
The GE Aviation facility also has to pass over 900 acres of off-site drainage through and around the facility, and in a way that allows for monitoring of on-site discharges to comply with their current NPDES permit. In order to fully understand the nature of the drainage from off-site areas, GE coordinated their efforts with ODOT (for information regarding I-75) and with the Hamilton County Storm Water District (HCSWD) in order to gather all of the information necessary to determine how storm water runoff was being conveyed to and through the GE facility.
The existing drainage system analysis of the facility was complicated by a lack of historical documentation within and outside of the facility for the existing system, 4 storm water pumping stations within the facility, and during the course of the study, four inverted siphons and one siphon was discovered to be part of the storm water system. The Mill Creek is adjacent to the GE facility and its impact on the ability of the GE facility to discharge runoff was explored through the modeling that was developed of the site.
This presentation will describe the challenges with the development of the industrial storm water master plan and how hydrologic/hydraulic computer modeling using the EPA SWMM version 5 software was used to meet the unique challenges to-date. This will include the data gathering necessary within the facility itself as well as the coordination and cooperation between the HCSWD, ODOT and GE to enable a comprehensive GIS data set to be built of the drainage network surrounding the GE facility. The presentation will also include a description of the unique hydraulic challenges of the site, the data available for calibration, and , the calibration approach, an analysis of the level of service provided by the existing system, and a discussion of what alternatives for improvement have been developed to-date for the site.