R2008-55 AUTHORIZING GIS SEWER MAP QUALITY CONTROL AGREEMENT

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.I#'AINBRIDGE MICHAEL H.PRICE,P E I � �` STEVEN G.BAINBRIDGE,P.E. �,[:i &ASSOCIATES, INC. CHARLES R.HUNSINGER,P E. Ili �IV�II�NSKI ConsuUing Engineers H.DAVID HARP,P e III March 28, 2008 ' Mr. Aaron Lawson II City of Decatur 'I #1 Gary K. Anderson Plaza Decatur. IL 62523-1196 Re: Professional Engineering Services Dear Mr. Lawson: I We are pleased to offer our engineering services to the City of Decatur for assistance in preparing a comprehensive sewer map of the community. As we understand the process, Eastern Illinois University (EIU) has identified the location of manl�oles using portable GPS units. EIU is now proposing to connect the manhole points on the map with lines representing underground sewers using the City's quadrangle i maps (quad maps) for reference. There will be instances where the GPS identified points will not correspond to the manholes shown on the quad maps. There will also be times when the quad maps indicate there should be manholes where none were identified by EIU. To correct these inconstancies,the City proposed to either use City staff or Tel Scan to resolve the conflicts by field investigations. Revisions will be sent back to EIU for incorporation into the map. In some cases, field inspections will not resolve the mapping conflicts and Bainbridge, Gee, Milans?:i & Associates (BGM) will become involved to assist in finding the solution. After the information gained from the field investigations has been input into the mapping process, any remaining anomalies will be sent to BGM for investigation. BGM will use engineering principles, available records and knowledge of the system in an attempt to resolve the conflicts. BGM and their employees have studied, mapped and inspected the Decatur Sewer System, designed changes to the system and answered similar questions for the City and Sanitary District for the past 34 years. The anticipated review process will involve three levels of effort. When maps are received from EIU, engineering technicians will log them. The first level of review will be done by an engineering tech. A technician will take a quarter section sheet and check it for connectivity and consistency. The City"s old quarter sections, BGM's sewer maps and record drawings of the system will be used for reference in checking the sheets. Areas of the map which are questionable or where there are conflicts will be taken to a second level of review by one of BGM's Technician/Draftsman. These individuals have many years of mapping experience, know many of the changes that have been made to the sewer system and are very familiar with the record drawings. Questions that can be resolved by simple surface investigations will be check in the field. Underground investigations are available, but outside the scope of these services. If there is still a question about the sewers in a specific area, a third level of review will be done by one of BGM's Principals. The senior principals of BGM each have over 30 years of experience working with, in and on the sewers of Decatur. Their knowledge of the working system, its history and available records will be used to resolve the more difficult problems. Finally BGM will review the entire sewer map for connectivity and label sewers as sanitary, combined or storm. The ownership of the sewer system is often in question. BGM will recommend a plan for ownership of the individual sewer lines by the City and Sanitary District based on historic records, past practices and engineering logic. 1670 S.TAYLORVILLE ROAD ■ 217/423-5600 ■ FAX 217/423-8677 ■ DECATUR, ILLINOIS 62521