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1 <br /> 3. EXISTING CONDITIONS <br /> 3.1 Sanitary Sewer <br /> The sanitary sewer system in the project area consists of nine-inch(9")and 18-inch <br /> (18") diameter vitrified clay pipe (VCP) installed in the 1950's. The joint sealing <br /> material in use at that time was typically an oakum and bituminous material. <br /> Previous internal inspections with a specially designed television camera have found <br /> the pipe to be in generally fair structural condition with numerous_offset joints,some <br /> cracked segments,some root intrusion and mineral deposits at joints,and some dips <br /> with solids deposition. <br /> The calculated capacity of the existing 18-inch (18") pipe, in "new" condition, on <br /> ' Wilson Street ranges from about 1,500 gpm to 3,300 gpm depending on the pipe <br /> slope in a particular segment. <br /> Wastewater flow in the City of St. Anthony is metered by the Metropolitan Council <br /> Environmental Services(MCES)at four locations. Meter number 104 is located on <br /> the southern boundary of the City at the end of the 18-inch (18") sewer on Wilson <br /> Street. This location provides flow records for the majority of the Community. <br /> According to MCES records,the wastewater flow in the St. Anthony sanitary sewer <br /> ' system increases significantly during spring runoff conditions and during and after <br /> heavy rainfall events. Under normal dry weather conditions(January 1997)the flow <br /> at meter M-104 averages about 300 gpm. The flow increases during wet conditions <br /> (July 1997)to an average of about 770 gpm. On the peak day in July 1997,the flow <br /> recorded at the MCES metering point reached an average of about 1,400 gpm over <br /> the entire day. Instantaneous peaks certainly were higher than the average for the <br /> day,however,without additional data it is difficult to reasonably estimate the amount <br /> of flow in the system under these short term conditions. <br /> During the high flow period in July 1997 there were numerous reports of sanitary <br /> sewer lines backing up into the residents basements along 29'Avenue and Wilson <br /> Street. In some cases the sewer backups are a regular occurrence and residents have <br /> ' been investigating methods of installing back-flow protection like a check valve or <br /> a gate valve. <br /> ' In consideration of the capacity calculations,anticipated peak flow rates and reports <br /> of system backups, it can be concluded that the sanitary sewer system in the project <br /> area does not have sufficient capacity in it's current condition to convey the <br /> anticipated wastewater flow rates. <br /> 3.2 Watermain <br /> ' The existing water distribution mains in the project area were installed in the 1950's <br /> of ductile iron pipe (DIP). The service connections are expected to have lead <br /> "goosenecks" and galvanized or copper service lines to the individual homes. In <br /> ' general,the system has provided good service but main breaks are becoming more <br /> ' . City of St.Anthony-1999 Street&Utility Improvement Project <br /> Feasibility Report A <br /> ' WSB Project No.1065.21 `YSB <br /> e-� <br /> Page 4 <br />