Village flood control efforts preempt, respond to rains
It rained on and off for 10 days straight in the village of Downers Grove, Ill., in April 2013. It rained, and then it poured, dumping 6.7 in. on the community in 24 hours. For days, standing water flooded areas of the town, which lies about 25 miles west of Chicago. The village’s Lacey, Prentiss and St. Joseph creeks overflowed, adding to runoff from impervious areas. Before the downpour on April 18, consistent rain had already saturated Downers Grove’s ground. The week and a half of precipitation more than overwhelmed the village’s storm water system and 150 localized poor drainage areas (LPDAs).
“There was significant flooding throughout the village, including in homes, backyards and streets,” said Karen Daulton Lange, P.E., storm water administrator for the village of Downers Grove. “Flooding was most severe in floodplains and in LPDAs. In floodplains, the flooding occurred because creeks and streams overflowed. Flooding occurred in other areas outside floodplains because the storm water exceeded what could be handled by existing storm water infrastructure.”
After the heavy rains last year, DuPage County was declared a disaster area. The nearly 50,000 residents of Downers Grove experienced widespread damage from the spring storm, which was one of four flood-inducing heavy rains in the village over the past decade. Village officials knew they needed to amplify current methods to control flooding in the area, an initiative they launched in 2006.
WIIPing Up a Solution
Downers Grove updated its Stormwater Master Plan in September 2006, just one month before the village faced inches of rain and widespread flooding.
“Talk about timing,” Lange said. “This big-picture strategy plan was developed to address existing storm water problems in the village, the condition of the storm water system, the adequacy of system components and estimated costs for necessary maintenance, capital improvements, and regulatory requirements.”
The Village Stormwater Utility Exploratory Committee and village staff determined recommendations detailed in the plan. Three priority projects were established: Brooke/Centre drainage improvement, Seeley/Janet storm sewer replacement and St. Joseph Creek dredging between Mackie and Carpenter.
Then, inches of rain fell in October 2006. The village worked with four consultants to review and analyze flood control efforts relating to each of its three watersheds.
“The Watershed Infrastructure Improvement Plan (WIIP) was the result,” Lange said. “Approved by the village council in September 2007, the WIIP identifies areas in the village where drainage and flooding issues exist and recommends specific solutions to each problem area according to high, medium and low prioritization guidelines.”
WIIP includes 55 projects. The village completed 26 of them between 2008 and 2012, beginning with those categorized as high priority. Although storm water management projects did not focus on private properties, the public land efforts intended to reduce stress on residents’ lands, too. A majority of the town’s LPDAs, or flood-prone, “bowl-shaped” locations, are on privately owned property, as are major portions of the watersheds of the three creeks.
“These infrastructure improvements, intended to alleviate flooding in areas underserved by storm water infrastructure or with persistent drainage problems, reduced the amount of flooding in the areas they serve,” Lange said.
The village worked with consultants again after the April 2013 flood to establish more than 20 new storm water management projects. Seventeen of them, outlined in the 2013 Storm Water Report, are slated for construction in 2014.
The plans intend “to comprehensively address deficiencies in the infrastructure and maintenance of the public storm water system,” Lange said. They result from “information provided by residents and business owners through personal meetings, photos, e-mails, surveys and videos.”
With two management documents written and funds secured in bonds and fees, Downers Grove is prepared to focus on three major areas of improvement: storm water storage, storm water conveyance, and maintenance of storage facilities and conveyance system.
To assess and address these topics at the town’s three creeks, which feed the DuPage River, Downers Grove hired four consultants in 2006 and 2013. Christopher B. Burke Eng. Ltd. and Engineering Resource Associates Inc. worked on north and south St. Joseph Creek, respectively. V3 Co. focused on Lacey Creek, and Clark-Dietz Inc. analyzed efforts at Prentiss Creek. Each partner used “historical data, recent flooding information, supplemental survey data, field visits, and past and present resident input” to design the improvement projects found in WIIP and the 2013 Storm Water Report, according to Lange.
The storm of April 2013 tested the village’s efforts and demonstrated which areas still needed improvements and which did not.
“The Prentiss Creek area is on the south side of town, which has more recent development with more modern storm water management systems,” Lange said. “This area did not experience the same level of flooding in the 2013 event, so we did not do further analysis on this area.”
Another successful storm water project completed in the village involved
collaboration with the Downers Grove
Park District. The Washington Park Stormwater Improvement Project renovated the park for public recreation while also providing flood relief. The Illinois Section of the American Society of Civil Engineers awarded the project an Outstanding Civil Engineering Achievement Award, which also was granted to the 2nd and Cumnor naturalized basin and storm water improvements.
There, “the village purchased homes that had repeated flooding and provided storage to contain storm water discharge of high-intensity, short-duration storm events,” Lange said. “This basin lowered the water surface elevation of flooding events that significantly reduced the need for road closures, all while providing benefits to increase water quality of storm water discharge.”
The village affords its storm water improvement projects by implementing a storm water utility fee. Property owners pay based on their land’s impact on the village’s storm water system, calculated by the impervious area on their property. Lange said the effect of the fee is two-fold: creating funds for storm water management and raising public awareness.
“While this has helped by having a dedicated and predictable source of funding, it has also created an awareness that was not as prevalent when funding was from property taxes,” she said. “Resident demands for improved storm water management have increased significantly.”