09/02/2008 Council Packet - Laserfiche WebLink

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Production: In Addition to the five existing wells detailed in table 8 -1 the Water Plan has identified an additional 7 wells will need to be constructed to meet demands of full build out. Figure 8 -4 shows the proposed locations of the seven additional wells No. 6 through No. 12. The proposed locations of wells No. 6 through No. 10 are on City or School District Property and wells No. 11 and No. 12 will require the purchase of land for well construction. Wells No. 6 through No. 12 will utilize the Jordan Sandstone Aquifer, which is the water source for the 5 existing wells. The additional wells required are based on the forecasts in chapter one and the full build out land use for the City. Well costs in 2008 dollars and well construction timeframes are shown Storage: Additional storage above and beyond the existing storage shown in Table 8 -5 will be required to meet future water demand. The water plan is projecting that an additional 2.5 to 3.0 million gallons of storage will be required. This storage is proposed to be constructed at the water treatment plant site prior to the construction of the treatment plant at either of the two site options (the intersection of Birch Street and Centerville Road or on Birch Street East of 12th Avenue) as shown on figure 8 -4. Ground storage stores water at ground level and requires the construction of a booster station to move water to the elevated towers where the pressure for the water system is obtained. Ground storage will benefit the treatment plant operations, when constructed and has a cost savings over the construction of an elevated tower. The amount of ground storage required to meet demand is based on the forecasts in chapter one and the full build out future land use. Water Treatment Facility and Raw Watermains: The City completed a Treatment Study in 2007. This Study reviewed potential locations, needs, and infrastructure required for a central treatment plant, and the resulting costs. The City has not yet proceeded with a plant but retains that as a potential long range goal. The 2007 Treatment Study has been updated with the 2008 Water Plan to reflect the forecasts in chapter one and the full build land use. Table 8 -3 above shows the levels of iron and manganese at each of the existing five City Wells. The City currently used poly - phosphates to sequester the iron and manganese. The levels noted in table 8 -3 do not pose any health threats to residents. The level of resident satisfaction with the quality of City water may warrant the need for the treatment plant. The water treatment plant was sized to serve the forecasts of chapter one and the full build out demand in the City. Figure 8 -4 shows the location for the water treatment plant. This location will also house the ground storage, a booster pump, and two wells. The proposed water treatment site option on Birch Street east of 12th Avenue is on school district property. Costs for two sites were analyzed based on the infrastructure required to incorporate the treatment plant into the water system. The site option on Birch Street east of 12th Avenue had a lower cost, because of its proximity to the well locations. Raw watermain is required to link all of the wells to the water treatment plant. Raw watermain will carry water pumped from the Jordan Sandstone Aquifer to the plant where it will be treated and blended into the water distribution system. The site option on Birch Street east of 12th Avenue has the lower cost because the amount of raw watermain required is less than that at the other propose site. The raw watermain has been sized to carry the water pumped by the wells to either treatment plant as shown on figure 8 -4. The raw water will be constructed to each existing well at the time of the treatment plant construction and with each additional well constructed after the treatment plant. The costs and a timeframe for raw water construction are shown in table 8 -9. It has been recommended that the water treatment plant use a method called blending, where treated water is mixed with untreated. The blending option is used by many cities in their treatment facilities, and provides cost savings for the City because the plant size is reduced due to blending. On days with high water demand the blending method may cause higher iron and manganese levels because the plant will not be able to treat water at the rate of consumption. The treatment plant will use filters to remove 8 -17 • • •