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r Alternative Trunk Water System Design March 13, 2003 Page 2 achieve a reasonable fire flow at a reasonable cost. A summary of the results ol our analysis follows. Wells One conventional design consideration is to plan for the possibility that the largest well might be out of service for routine or emergency maintenance during a fire. The combined capacity of the remaining wells is considered the “firm” pumping capacity. Our review of the well log for Long Lake Well Number 2 indicates that it could be rehabilitated to have a capacity of 1,000 gallons per minute (gpm). A rehabilitated well, new pump, new motor, and new electrical equipment would all be contained in the existing building. The wcllhousc has some operational and safety issues, fhe driveway that accesses the south side of the building is severely steep. A four-wheel drive pickup must be u.sed to make deliveries. The chemical vendor delivers chemicals to Wellhousc Number I where they are stored until needed at Wellhouse Number 2. fhen public works staff delivers the chemicals. It is proposed to install a new chemical feed system In a newly constructed upper floor. Adding a second floor and grading a driveway to the north side of the building would result in a much safer and elTicicnt chemical delivery system. The chemical vendor could deliver directly to Wellhousc No. 2. The upper level would contain the chemicals, chemical feed equipment, and SCADA (supervisory controls). An improved Well Number 2 would increase the firm pumping capacity of the merged system by 500 gpm, which would be critical during a fire. However, Long l.akc does not need this capacity for domestic purpo.scs. Either of Long Lake’s two existing wells could keep up with Long Lake s maximum day demand (without a fire). On the other hand, Orono has one well that is more than capable of meeting Orono ’s current maximum day demand, but with only one well, Orono ’s firm pumping capacity is zero. Orono would need to rely on Long Lake’s system for domestic needs if the Orono well was out of .service. It may mtike more sense long term for Orono to increase the firm pumping capacity of the merged system by constructing a second well with a 500 gpm or larger capacity. 'Ihe analysis a.ssumes the firm pumping capacity will be increased by 500 gpm. If Orono constructed a 1,000 gpm well, the firm pumping capacity would be increased by 1,000 gpm. Trunk Water Main Changes I he attached Figure I indicates the water system now recommended. The available fire flow would be 3,000 gpm for a three-hour period. This is not a significant reduction in capacity from the previous analysis that resulted in 3,500 gpm fire flow for a three-hour period. It is still much belter than existing conditions. (If Orono constructed a 1,000 gpm well, the available tire flow would be back up to 3,500 gpm for a three-hour period in most critical locations.) Highlights of the alternative sy.stem follow. Implementation of Orono ’s trunk water main system is proceeding diflerently than originally anticipated in the previous computer model. Orono is constructing a 12-inch water main in Kelly I’arkwa)’ all the way to Willow Drive and in Willow Drive southerly to West W’ayzata