Scope of Work The Enterprise project encompasses 4.53 acres located at the northwest corner of the intersection of Zemke Blvd. and Mannheim Road in the City of Chicago. The project consists of a rental car facility with a main customer service center, an automobile maintenance center and a fueling station. This facility is being constructed to provide Enterprise Rent-A-Car with a location within the boundaries of O’Hare International Airport. Marchris Engineering, Ltd. was able to assist Enterprise Rent-A-Car and the project architect with this interesting and complicated project. The project included incorporating a large easement for a high-pressure watermain traversing the property, interaction with the various on-going projects within the airport, meeting specialized City of Chicago requirements for stormwater, and designing the site in order to meet and obtain LEED credits. The project coordination included working with the airport and Commonwealth Edison in order to coincide with the airport’s utility expansion as well as Commonwealth Edison’s expansion of main conduits which were to run under a portion of the Enterprise site. The project also included reconstruction of a significant portion of Schilling Road which is adjacent to the site. The requirements for detention included designing the parking lot and storm system which will accommodate a 100-year anticipated storm as well as limiting the discharge.
As part of an initiative to provide sustainable development, several items were developed as part of an overall stormwater treatment plan for this project. The landscape area for the project was increased to provide 20% of landscape area coverage to facilitate stormwater infiltration and reduce the burden on the adjacent storm sewer and water way system. The facility was constructed with a detention system that stores water underground as well as on the parking lot. This allowed a restricted outlet to be placed upstream of the water quality device. Because the restricted outlet significantly reduces the storm discharge rate, 100% of the site runoff can be captured to remove VOC’s from the parking lot runoff.
Permeable pavers were placed within selected portions of the parking lot to encourage infiltration into the subgrade below the parking lot. This was done in conjunction with the JAWA (Joint Action Water Agency) to facilitate positive stormwater flow to the anode field which underlies the site. In addition, the permeable pavers will allow water to percolate and be treated through the fine gradation material under the paver blocks. Due to the smaller size of the sub-base material there is an increased surface area allowing greater potential treatment prior to any collection within the underdrain system. Using the combination of pavers, increased landscape area, restricted outlet and treatment device prior to exiting the site, the overall water treatment capabilities of the storm system are enhanced. LEED credits were obtained for the water quality and the retention facilities.