Agenda - Council - 02/19/2008 - Special

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CITY COUNCIL WORK SESSION Topic Report: CONSIDER PURCHASE OF A SEWER JET VAC TRUCK By: Steven Jankowski, City Engineer and John Nelson, Utility Supervisor Background: The City's rapidly expanding sanitary sewer system currently has 48 miles of gravity flow sewer. Although such sewers are theoretically designed to be self cleaning, in practice periodic maintenance is required. In fact, it is recommended by the City's insurer, the Minnesota League of Municipalities, that sanitary sewers be cleaned on a regular basis that is reasonable and economically feasible. Most cities having sewers of the age and constructed of material similar to that of Ramsey' s system have selected between two to four year cleaning intervals. For example sewers that receive discharges from restaurants and other oil and grease generators are likely to need cleaning and inspection on more frequent basis. It has been suggested by the League that a record of the cleanings be made and that the cleaning frequencies be adjusted based upon the findings of previous cleanings. Such records of the cleaning are essential as a defense against claims against the city in the event of a sanitary sewer backup and that. Attached to this case is a model Sanitary Sewer Maintenance Policy developed by the League. Ajet vac truck has been the state ofthe art for cleaning sewer over the past several decades. This equipment has a high pressure jet nozzle that propels itselfthrough the sewer. Once it is extended through the length of the sewer to be cleaned it is reeled backwards with the jet pressure wash still running. This washes solids downstream to the launching manhole where a vacuum unit sucks out both the solids and the water. The City currently contracts with a private vender for this service. Last year, which was typical of recent years the utility spent $15,000 to clean 32,200 feet of sanitary sewer. At this current rate of annual cleaning the City would realize a cleaning interval of7.9 years which is less than half the recommended rate of cleaning for a system of our type. For the purpose of the following analysis and discussion, it will be assumed that on average the City's sewer system should be cleaned on a three year interval. For the utility to contract to clean the full one third of its sewer system the annual cost of contracted cleaning would be $42,800. The City has budgeted $300,000 in 2008 for the purchase of a jet vac truck with $255,000 coming from the Sanitary Sewer Utility and $45,000 coming from the Storm Water Utility. With an estimated service life of 15 years the annual cost of cleaning the annual goal would be $20,000 per year for the equipment and $8,100 in personnel time from the public works and