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<br />~ <br /> <br /> <br />~ <br />EN HILLS <br /> <br />MEMORANDUM <br /> <br />DATE: <br /> <br />May 23, 2007 <br /> <br />AGENDA ITEM 7.C <br /> <br />TO: <br /> <br />Mayor and City Council <br />Michelle Wolfe, City Administrator <br /> <br />Kristine Giga, Civil Engineer ~ <br />Greg Hoag, Public Works Directo~ <br /> <br />FROM: <br /> <br />SUBJECT: <br /> <br />Approve a Proposal dated May 7, 2007 and Authorize Staff to Contract <br />with Bonestroo for an Infiltration and Inflow (III) Study for the City iu <br />an amount not to exceed $9,600 <br /> <br />BACKGROUND <br /> <br />As part of a joint solicitation with the City ofRoseville, City of Arden Hills staff has requested <br />proposals from 5 consulting engineering firms to assist us in identifying Infiltration and Inflow (III) <br />sources within the City of Arden Hills. Prior to bringing these proposals to the Council for <br />consideration, we wanted to provide a brief background on why III is a concern for the City of Arden <br />Hills. <br /> <br />The majority of Arden Hills' sanitary sewer system was constructed in the 1950's and 1960's, along <br />with much of the current housing stock. The City's sanitary sewer system includes more than 42 <br />miles of sewer piping and 14 lift stations. <br /> <br />Wastewater treatment for the City is provided by the Metropolitan Council Environmental Services <br />(MCES) at the Metro (Pig's Eye) Plant located in St Paul. The City of Arden Hills is billed by the <br />MCES for the use of the interceptor sewer system and treatment of the wastewater at the Metro Plant. <br /> <br />The City's wastewater flow is determined by the MCES through three separate meters. <br /> <br />What is III?: Infiltration and inflow (III) is defined as clear water flow that would not require <br />treatment had it not been mixed with wastewater. This water may enter the system through manhole <br />covers or manhole wall joints, fractured pipe or other pipe deficiencies, or rain leaders from roofs of <br />buildings that may be connected incorrectly to the sanitary sewer system. Once clear water enters the <br />sanitary sewer system and becomes mixed with wastewater, it must be treated prior to discharge to a <br /> <br />\\R VNAS 1 \AHdata$\PR&PW\Engineering\2007\Council_ Actions\5~29M07Memol&I.doc <br />