Item 7B, Inflow and Infiltration Update

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1&1 5/8/2008 Page 2 flow" and "high flow". High flow occurs when we receive significant rain events. However, if we have a drier than normal period, the length of time the meters are in place may need to be extended. Smoke testing Smoke testing is recommended to occur in the summer, after the streets are swept and catch basins are cleared of leaves and debris. This allows the smoke to be more visible to those completing the testing. Staff is working with Bonestroo to coordinate this work for June. At this time, the consultant recommends the following areas be included in smoke testing: the area flowing to the Glenarden neighborhood (proposed 2009 PMP), and the area flowing to Lift Station #11 (northwest corner ofthe City.) Sanitary Sewer televising The process to televise sanitary sewer lines is two-fold. One two-person crew is needed to clean and jet the lines prior to televising, and another two-person crew follows with the televising equipment. Last summer each of these crews consisted of one full time employee and one seasonal employee. The cleaning crew periodically needs an additional crew operating the vactor truck to suck excessive debris from the manholes. Staff estimates that we are cleaning approximately 450 feet per hour, and televising 500 to 600 feet per hour. Areas to be televised: In 2008, staff is focusing on televising sewer lines in low and/or wet areas, especially near ditch systems and lakes. 23,500 feet (4.5 miles) of televising is planned around Round Lake, Lake Johanna, along Highway 10, and in the Valentine Avenue neighborhood (between Lake Valentine Road and 694). Staff estimates that it will take about 52 hours to clean and 47 hours to televise these lines, which is scheduled for completion by the in early June. Once these areas have been televised, staff will continue to work on other areas ofthe City left to be televised. In 2007, approximately 61,000 feet (11.5 miles) were televised. Through 2007, approximately 65% (27 of 42 miles) of the City has been televised. Staffs goal is to televise approximately 30,000 feet (5.7 miles) in 2008. Manhole inspection Manhole inspection also involves a two-person crew; for safety reasons, a two-person crew is required if manhole entry is required for detailed inspection. It takes approximately 20 minutes to complete a manhole inspection (or 0.65 total man hours). We have identified three areas in the City for manhole inspections in 2008; 147 manholes are located in these areas. Staff estimates approximately 50 hours for a two-person crew to complete the identified inspections. Once televising is cornpleted, the crew will switch gears to manhole inspection; this work will be completed in mid June. As we gather additional information from other analysis such as flow meters, staff will identify additional areas where manhole inspections should be completed.