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5. Water System Improvements ProjectREPORT TO: Mayor and City Council FROM: William Shaw, Director of Public Works SUBJECT: Water System Improvements MEETING DATE: October 3, 2011 BACKGROUND: In July 2011, the Council approved Morrison-Maierle Engineering as the Engineer of Record for water system improvements. The Council did not authorize the Department to proceed with the assignment of the work until it returned to inform the Council as to why the work could not be performed by the current staff of the Department. In this report I wish to accomplish several things: Inform the Council of the current and near term projection of staffing level for the Public Works Engineering and Administration Divisions. Discuss briefly the Capital Improvement Plan for water improvement projects proposed to be designed in the initial request for assignment to the Engineer of Record. Currently the support staff that would normally be assigned projects of this nature include the following positions: the director, one senior engineer (assigned as the water, sewer and storm water superintendent), two engineering technicians (one is the GIS technician and the other a storm water technician), one construction inspector and one document/project specialist. No additional hiring is anticipated in the near term. I believe that staff could produce the design, construction documents, and inspect construction of these projects, but could not likely handle all five if construction were necessary in the spring of 2012. Staff will require guidance from Council as to the desirability of commencing construction of all or some of these projects by spring. RECOMMENDATION: To grant authorization to proceed with Morrison-Maierle Engineering Contract. I UT us H, I 19"MR39 a UT F.11 I of M10111SKI 1V tO IN Do a] MTAvv ALTERNATIVES: As suggested by the City Council Respectfully! submitted, William Shaw Director of Public Works Attachment: Project List n Jane Howington City Manager Among the list of the project provided in July are the following: WEX 28 would install an 8 inch piping within West Colorado between 5th Avenue WN and Highway 93. The existing piping network provides two dead-end mains to the area'; several of the occupied lots along Colorado are nearly 500 linear feet from the nearest fire hydrant (300 to 400 is standard ' practice). The piping shown existing in Arizona Street connects NA_ directly to the Buffalo Hills Lower Zone Water Reservoir. Notice too that projects WEX 29 and 138 are also proposed in the immediate vicinity; neither project ` by WEX 28. DNA ST _gip, I'- Legend aWater r water main line piping N a fi - �- would resolve issue covered Project WEX 30 is in a area served currently with a 2 inch water main; distances to fire hydrants from structures are adequate pressure at the structure; this piping is connected to thi zone and some of the closest to the reservoir elevation (see Water Elevation and Pressure). These factors indicate that the facilities could experience residual pressures below 20 psi depending upon the water network conditions. Pressure of 20 psi are considered minimum allowable; this pressure provides adequate flow to most water using facilities but also acts to prevent flow back to the piping network from connected facilities. 1 Proposed new piping in the mapping is denoted in the legend as "water" and existing piping is denoted as "water main piping. Water Elevation and Pressure The City's water system pressure is provided by the elevation head obtained by pumping water to it principal reservoirs located on Buffalo Hill and Sheepherder. The vertical elevation difference between the water level in the reservoir and the water using facility is the main factor that determines the pressure at the facility. Pressure anywhere in the system is very localized and is reported in two increments: static and residual. Static is the pressure experienced at a location when the major influence is principally the height of water in the reservoir. Residual pressure is the pressure experienced when the area is being impacted by high water demand (e.g. irrigation demand or fire hydrant use); this pressure is greatly influenced by number of factors such as elevation head, piping flow restriction ( e.g. pipe size and friction loss) and pump run cycles (pumps are below the reservoir and in this piping system deliver water to the reservoir through the piping network; thus, when running they produce enough pressure to overcome the pressure exerted by the water in the reservoir.) The reservoir water level regularly fluctuates in height over an approximate 18 feet range ( each foot in height is about .433 pounds and down stream users would experience about 7.5 psi difference in pressure). WEX 132 is immediately adjacent to WEX 30 and the needs are similar due to piping size and location. The fire hydrant located at Arizona and 1st is close to the juncture of a 2 and 4 inch main; if pumping apparatus were connected to the hydrant the area could experience a negative line pressure. WEX 31 project crez in Hawthorn Avenue Interconnection of main line piping is what creates a network. A broad network is desirable because it spreads impacts over a much larger area of influence thus reducing localized impacts to residual pressure. WEX 154 replaces an existing 6 inch water main that is reported to have experienced sufficient corrosion to warrant replacement. Frequent repairs to piping segments are usually an indication that the piping material may not be suitable for the soil conditions found the area. While repairs can continue each repair job involves disturbance to other utilities in the area and a patch to the street; all of these reach a point where cost of repair overcome the cost of replacement.