2009 - Illinois DNR - State of Illinois

ALTERNATIVE D9 - COMBINE STORAGE ALTERNATIVE S11 WITHCONVEYANCE IMPROVEMENTS AT RANCHO LANE, DEE ROAD (C7) ANDBETWEEN THE CONFLUENCE AND BELLEAU LAKE (C8)To achieve flood damage reduction benefits throughout the watershed, this alternativewould combine various storage and conveyance alternatives including construction of apump station a Lake Mary Anne, modifications to the Dude Ranch Pond, modificationsto the Lutheran General Hospital Pond, construction of a new reservoir on the MaineTownship High School campus, modifications to Belleau Lake, culvert improvements onPrairie Creek at Dee Road and Rancho Lane and Lower Farmers Creek conveyanceimprovements. Each of the components of this alternative are described below.The Dude Ranch Pond, a 5.4 acre pond located south of Golf Road and east of the Tri-State Tollway, would be enlarged and connected to Farmers Creek to increase upperFarmers Creek storage by 30 acre-feet. Storage in the pond would be controlled by anew 48-inch diameter outlet pipe through a provisional Class I dam structure constructedin the Farmers Creek channel just downstream of the existing pond. A pump stationwould be constructed on the south shore of Lake Mary Anne to pump water from LakeMary Anne to the Dude Ranch Pond. A 10 cfs pump station, with an 18-inch diameterdischarge pipe, constructed at the existing outlet of Lake Mary Anne and pumping in tothe Dude Ranch Pond, would provide Lake Mary Anne greater outlet capacity andprevent 100 year frequency event water levels in Lake Mary Anne from reaching mostfloodprone structures. The normal pool elevation of Lake Mary Anne would remainunchanged at 632.5. Overflows from the existing IDOT Golf Road interceptor sewerwould also be stored and controlled by the expanded Dude Ranch Pond site.The Lutheran General Hospital Pond Alternative, S3, would be supplemented with anadditional 50 acre-feet flood storage provided on the Maine Township East High Schoolcampus immediately south of the Lutheran General Hospital Pond and DempsterAvenue. Existing soccer fields located on the southeast corner of the Maine TownshipEast High School campus, would be lowered up to 7.5 feet and the sides graded at aslope of 3:1 to create a new reservoir. These athletic fields currently provide somedetention for local stormwater runoff. Three soccer fields would fit in the bottom of thereservoir. A ten foot service road around the perimeter of the area would providemaintenance access to the reservoir. A 60-inch diameter culvert would be installed toconnect the new gravity in and gravity out High School Reservoir to an existing 60-inchDempster Avenue storm sewer, tributary to Prairie Creek, on the Lutheran General109