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_ Y <br /> BA�NBRIDGE MICHAEL H.PRICE,P E. <br /> ��� & ASSOCIATES INC. STEVEN G.BAINBRIDGE,P.E. <br /> � CHARLES R.HUNSINGER,P.E. <br /> .�I��LANSKI ConsuUing Engineers EDWIN V.MILANSKI,P E.(CONSULTAN� <br /> CHARLES N.BAINBRIDGE,P.E.(CONSU�TnNr� <br /> July 9, 2003 <br /> Matthew C. Newell, P.E. <br /> City Engineer <br /> 1 Gary Anderson Plaza <br /> Decatur, IL 62522 <br /> RE: Ridgeway Drive—Bay Shore Drive <br /> Sanitary Sewer Study � <br /> City Project 2002-26 <br /> BGM 02-074 <br /> Dear Matt: <br /> On September 30, 2002, the Decatur City Council authorized Bainbridge, Gee, Milanski & Associates, Inc., to II <br /> review the sewer system in the Ridgeway Drive — Bay Shore Drive area in order to provide the City with <br /> realistic options to correct those conditions contributing to the SSO's. <br /> The time required to perform a satisfactory review and analysis of the sewer system in the Ridgeway Drive area <br /> is proving to be greater than originally estimated. Cost estimates and economic comparisons for several <br /> alternatives remain to be completed, but the expense involved in achieving the cunent state of the report has <br /> exceeded the agreed cost of$30,000.00. <br /> Part of the increased expenses is due to incorrect da.ta on the available quarter section sheets. In order to <br /> meaningfully calculate the capacities of the sewers in the study, accurate elevations were necessary. This <br /> required our field crew to establish the true elevations of ma.nholes and sewer inverts in the study area,which in <br /> turn required recalculation of many of the capacities in order to make them consistent with the new elevation <br /> data. This work was outside the scope of the Agreement. <br /> Analysis of the flow monitoring data took longer than expected due to an anomaly in the information where the <br /> data indicated that flow was moving tiom an area of low head to an area oi high head. This required substantial <br /> investigation to resolve. Also, some reconstructing of flow data was necessary to establish baseline flows at two <br /> monitor sites where low flow conditions could not be adequately monitored. <br /> Lastly, this study had originally planned on using flow data from 2002 that was gathered concunently with the <br /> Kaydon Drive flow monitoring. The rainfall events that produced satisfactory data in the Kaydon Drive area, <br /> though, did not produce similar effects in the Ridgeway Drive area. Determining this, however, required a <br /> certain amount of data analysis and review of all the available information. We then prepared an alternative <br /> flow monitoring plan that included five monitoring sites,which was two more than originally planned, and some <br /> re-televising of certa.in key sewers as well as new televising of other sewers. <br /> The revised flow monitoring plan, the expense of maintaining e�ctra flow meters, the review of additional <br /> televised inspections, and the incorporation of the data from additional flow meters required a level of effort that <br /> was not originally envisioned. Nevertheless, these changes to the initial study scope have proved to be very <br /> helpful in the analysis of the problems along Ridgeway Drive. <br /> 1670 S.TAYLORVILLE ROAD ■ 217/423-8600 ■ FAX 217/423-8677 ■ DECATUR, ILLINOIS 62521 <br />