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515 Little Canada Road, Little Canada, MN 55117 -1600 <br />(612) 484 -2177 / FAX: (612) 484 -4538 <br />MEMORANDUM <br />TO: Mayor Fahey & Members of the City Council <br />FROM: Scott Tangen, Public Works Director <br />DATE: February 20, 1998 <br />RE: Infiltration/Inflow and Sump Pump Inspection Program <br />MAYOR <br />Michael I. Fahey <br />COUNCIL <br />Beverly Scalze <br />Jim LaValle <br />Steve Morelan <br />Bob Pedersen <br />ADMINISTRATOR <br />Joel R. Hanson <br />In 1996, we began sanitary sewer televising of our City's sewer system to identify areas of <br />infiltration/inflow (UI). To -date, we have televised approximately two - thirds of the City's <br />sanitary sewer system. I have viewed approximately 90% of the tapes and am putting together a <br />plan to correct those deficient areas. As of today, I have identified 23 areas that will require a <br />contractor to repair. The repairs range from fractured pipe to offset joints that do not allow <br />cleaning equipment through to one spot that is leaking at an estimated five gallons per minute. A <br />one gallon per minute leak contributes 525,000 gallons per year and costs the City approximately <br />$700 per year in treatment costs. The payback period to repair a one - gallon per minute leak in <br />an average depth, unpaved area is approximately a year and a half. I am in the process of <br />evaluating whether these repairs will require excavation or if they can be made in place (cured - <br />in -place pipe, grouting, lining, etc.) Each repair will need to be evaluated on an individual basis <br />due to the pipe type, size, location, depth, flows, and extent of damage and/or leakage. <br />Along with the televising of our system, we have identified numerous areas in the City that we <br />have added to our roots "hot spots" cleaning list and our grease "hot spots" cleaning list. These <br />tapes have been invaluable in allowing us to identify potential problem areas in our system. In <br />1998, we will finish televising the remaining one -third of our system. This televising work <br />should be completed by the end of July. <br />Our Public Works Department has also been inspecting each manhole. As part of this manhole <br />inspection program, we have identified which manholes need to be grouted, inverts to be <br />repaired, chimney seals needed, or other miscellaneous work to help reduce our I /I. I will be <br />putting together a program for this repair work and it will begin this summer. Most of this <br />manhole work will be done by our Public Works Department. <br />Page 80 <br />