May 1, 2006
ERA completed a stormwater analysis to determine the cause of the flooding and developed potential solutions

LEMONT, Ill. - Downtown areas within the Village of Lemont experience significant flooding as a result of a 460-acre tributary area that drains into an undersized downtown tunnel/storm sewer system. ERA completed a stormwater analysis to determine the cause of the flooding and developed potential solutions for specific levels of flood protection. The study included extensive TR-20 and HEC-RAS modeling of detention facilities and channel reaches throughout the basin.

ERA's final design solution included restricting an existing 6' x 6' box culvert with a 2.5' x 4' culvert. The restricted pipe will continue to allow smaller storm events to drain into the tunnel and will allow the remaining water to enter a large stormwater management facility that will be constructed.
The stormwater facility will be created utilizing an existing depressional area and constructing a large berm on the downstream side. The berm will be over 10-feet in height and will impound over 28 acre-feet of storage. A State of Illinois Office of Water Resources Dam Safety Permit was required, and final plans, specifications and cost estimates have been completed for this project. Construction is slated for Summer 2006.

Engineering Resource Associates, Inc. (ERA) is a full-service consulting engineering, environmental science and surveying firm serving Midwestern clients since 1990. With offices in Warrenville, Geneva and Chicago, ERA offers broad experience on a wide variety of projects for public and private sector clients. For more information about ERA, call (630) 393-3060 or visit us online at www.eraconsultants.com.