Jul 10, 2020

Making the Grade: Storm Water Solutions

Storm water improvements upgrade Chicago-based college campus 

student lot 1

Olive-Harvey College (OHC), located in Chicago’s historic Pullman neighborhood, offers a number of programs in Transportation, Distribution and Logistics (TDL).  

OHC offered Primera’s Civil Engineering Team with numerous opportunities to solve storm water-related challenges as part of the design team with FGM Architects and landscape architects Jacobs/Ryan Associates redeveloping seven acres of the 1950s-era campus into a state-of-the-art new TDL Center. Storm water challenges included runoff from the new 103,000 square foot TDL building, new roadways designed for commercial vehicle traffic, depressed loading docks and improved and new impervious and pervious parking areas. The greatest challenge was designing and constructing the massive Commercial Driver Training (CDL) lot, comprised of three acres of continuous uninterrupted concrete surface, which relies on sheet drainage instead of catch basins or underground piping.  

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Although the entire OHC campus is nearly 69 acres, the large volume of storm water runoff, high water table and low soil permeability meant relying solely on infiltration was not an option. Primera’s civil design had to meet a variety of rate, volume and sedimentation and erosion control provisions set forth by the city of Chicago and the Metropolitan Water Reclamation District of Greater Chicago's (MWRD) storm water permitting requirements, the Illinois EPA’s Erosion and Sedimentation Control Plan and LEED Silver Quantity Control and Construction Activity Pollution Prevention guidelines.  

bioswale
The volume of storm water runoff, high water table and low soil permeability meant relying on just infiltration was not

an option.
storm water bmp
BMPs utilized included rain gardens, bioswales and a biodetention pond. 

The OHC project followed the allowable release rate outlet capacity for a city of Chicago Regulated Development Area because the project does not discharge to the city’s combined sewer system.  

A privately-owned sewer receives all project drainage and leads into an MWRD Interceptor. The Interceptor System is an aptly named civil engineering marvel designed in the early 1900s to intercept sewer water that previously had entered Chicago area waterways, conveying it instead to water treatment plants. 

Action Plan

The first step was calculating the volume of required storage. Primera accounted for the new elements on campus, such as buildings, CDL practice lot, parking areas, depressed loading docks, roadways and pedestrian sidewalks. Approximately 7,000 square feet of permeable pavement was used where feasible to reduce runoff generated by the massive amounts of impermeable surfaces. The result of calculations was that roughly 2.5 acre-feet (approximately 814,600 gallons) of storage was required.  

The OHC TDL project area had no existing onsite storm water storage, giving the design team and OHC a blank slate.

Primera saw two potential paths: A more traditional approach utilizing typical urban, utilitarian-looking detention ponds surrounded by turf grass and concrete or a sustainability-minded approach incorporating literal and figurative “green” methods, such as biodetention ponds, bioswales/bioinfiltration and rain gardens. The two paths were discussed amongst the design team and with OHC. Given the college’s proximity to the Calumet Area Reserve, Big Marsh Park, Lake Michigan and two rivers, the incorporation of bio-elements was a “natural” fit and aligned with OHC’s sustainability, greenspace and environmental goals for the project.

Primera and Jacobs/Ryan Associates grew the plan from the functional landscaping and sustainable storm water idea into project-specific Best Management Practices (BMPs) that utilized rain gardens, four bioswales and a biodetention pond to accommodate more than 390,000 square feet of runoff tributary area. Given the site soil’s low permeability, the bioswales and biodetention areas could only provide limited infiltration into the existing site soils. Instead, they met OHC’s volume control storage requirements by providing storage in the stone and sand under them.

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Prior to improvements, the majority of OHC’s storm water runoff entered the sewer system within one hour. The bioinfiltration and detention areas hold the runoff and slowly discharge into the sewer system. Primera’s calculations estimated the new sustainable design would gradually release storm water over a 24-hour period.

Peak runoff rates were also reduced by 90%. Under the previous conditions, a 100-year storm event as defined by the city of Chicago Department of Water Management could create a peak runoff rate on the order of 50 cubic feet per second.

Primera’s calculations showed the implementation of the OHC project’s BMPs would reduce the same 100-year storm event’s runoff rate to no greater than 1.66 cubic feet per second.

Storm Water Strategy

Primera’s civil engineers worked with the FGM Architects and Jacobs/Ryan Associates to strategically locate the permeable pavers, rain gardens, bioswales and bio-detention areas throughout the redevelopment area to maximize storm water storage, slow the rate of storm water runoff and provide new greenspace. The 7,000 square feet of walkway permeable pavers receive almost 27,000 square feet of roof runoff. The remainder of the roof, sidewalk and roadway runoff is directed towards one of the four bioswale infiltration facilities. These facilities layer mixed soil media, crushed stone and geotextile fabric and utilize perforated piping for efficient distribution of collected runoff throughout the subsurface media. 

The greatest volume of storm water runoff is from the three-acre Commercial Driver Training lot. Primera designed the majority of runoff to sheet drain to perimeter rain gardens before continuing into the largest bio area on campus; a detention area with capacity of nearly 2 acre-feet or roughly 651,000 gallons, lined with native plants suitable for areas of variable inundation.

Jacobs/Ryan Associates, Landscape Architects, designed the stonework and plantings for the rain gardens and bioinfiltration areas, as well as landscape architecture for the rest of the site, tying in native plants and hardscaping elements throughout. Limestone outcropping stones were used to soften outfalls and provide slope protections at depressed curb cuts. Native plants, which can endure inundation for short periods of time, included grasses and forbs, such as such as Palm Sedge, Iris, Big Blue Lobelia and Spotted Joe Pye Weed (a favorite of monarch butterflies).

By implementing the BMPs, the Olive-Harvey site was able to meet or exceed storm water code requirements in a way that had social, environmental and maintenance benefits. The environmental benefits to using rain gardens, bioswales and bio-detention ponds are numerous, but chief among them are the reduction of sediments, metals and nutrients through natural filtering. Traditional storm water detention areas, though functional, are typically turfgrass requiring maintenance, such as mowing, irrigation, chemical herbicides and fertilizers while providing minimal aesthetic value. The bioswales, bio-detention pond and rain gardens at OHC contain a wide variety of generally low maintenance native plants that attract birds, butterflies and animals. The landscaping provides students, staff and faculty with greenspace where they can be serenaded by native birds while relaxing.

Primera partnered with FGM Architects and landscape architects Jacobs/Ryan Associates on the project, which was opened to students in 2019.

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About the author

Colleen Finkl is project manager for Primera Engineers Ltd. Finkl can be reached at [email protected]. John P. Fehlberg, PE, is civil engineer for Primera Engineers Ltd. He can be reached at [email protected].

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