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. , • . . _��r)� �{� <br /> aP``�\�11/ ��^, �I� <br /> � �T United States Department of the Interior n�wcn�� <br /> A <br /> 0 <br /> ' A GEOLOGICAL SURVEY <br /> ,_„r�>, 102 E. Main St. , 4th Floor �� � <br /> '�rcA 3�s�� Urbana, IL 61801 <br /> July 24, 1991 <br /> James R. Mayhugh , <br /> Water Production Manager I, <br /> Public Works Department j <br /> City of Decatur ' <br /> 1 Civic Center Plaza , <br /> Decatur, IL 62523 ! <br /> Dear Mr, Mayhugh: I� <br /> This letter concerns the discussions that we have had concerning conducting a <br /> seepage run on the Sangamon River. As we understand the City of Decatur has <br /> two wells, with a combined pumping capacity of approximately 5 million gallons <br /> per day, located near Hog Chute Bridge northeast of Decatur. The seepage run <br /> would be conducted to determine if groundwater pumped near Hog Chute Bridge <br /> has an affect on the quantity of water reaching Lake Decatur. <br /> This is an excellent time to conduct such a test. The Sangamon River at <br /> Monticello currently has a discharge of roughly 16 cfs; the addition of 5 <br /> million gallons a day, approximately 7.7 cfs, should be readily detectable, <br /> even with the uncertainties in discharge measurements. <br /> What we propose would be to make two seepage runs; one before the pumps are <br /> turned on and one several days after they are turned on. The first <br /> measurement would be used to determine natural low flow conditions. From Hog <br /> Chute Bridge to Oakley, the closest that we can measure to Lake Decatur, is <br /> about ten river miles. We would make five or six measurements, depending on <br /> accessibility, and from these we should be able to determine the fate of the <br /> water pumped in near Hog Chute Bridge. <br /> The cost for these two seepage runs would be about $2,500.00. This represents <br /> a conservative figure, and could be lower. Because af the uncertainties <br /> involve3 we felt it was necessary to start with the h�gh figure. Analyses of <br /> the data would be sent to you in letter form within two weeks of the day when <br /> the last measurements are taken. <br /> If this is agreeable to you please contact Richard Coupe at (217) 398-5358 to <br /> make arrangements. <br /> Sincerely yours, <br /> �� �v� <br /> r� <br /> Stephen F. Blanchard <br /> District Chief <br /> *2,2 <br />