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I I I I I I I I I I I I I I I I I I I This condition deserves careful consideration, since the first taps on the system are adjacent to the treatment plant and can receive water in about I minute. A preliminary assessment indicates that this condition cannot be corrected by modifications to the existing clearwell structure or changing current operations. CWorine feed equipment appeared to be operating normally; operators report that the feed rate can be visually observed. However, due to the hazardous nature of cWorine, we recommend that chlorine gas warning signs be placed in prominent locations within and around the building. In summary, addition of tankage, or its equivalent, for chlorine contact is required, external to the existing plant. The correction scheme will also require piping modifications. Note that cWorine residual data and chlorine feed rate data are not available. Without this data, a log reduction analysis for Giardia cysts cannot be performed in this preliminary evaluation. Operators report, however, that annual tests have been performed on treated water for Giardia cysts by a certified laboratory. All tests have been negative. High Service Pumps to Storalle/Distribution The high service pumps are rated as follows by name-plate data: Pump No.1 Worthington 75 HP 12M90-4 Pump NO.2 Worthington 40 HP 12LF4 900 g.p.m. @ 240 TDH 500 g.p.m. @ 240 TDH On the peak day of 1993, Pump No.1 pumped at 1043 g.p.m. for 15.6 hours. Using these data, the plant capacity with Pump No. lon-line, and adjusting for 3 backwash cycles under existing filter operations, is 1.32 MG in 24 hours. Production with the use of two pumps in parallel is now unknown. Such an estimate would require the analysis of piping, pump curves, and system curve characteristics. However, a conservative estimate, factored by 0.75, is about 1.46 MGD. Because all finished water must be pumped into the system for use, these pumps remain the primary hydraulic constraint on capacity. At the same time, no standby power source is available to the plant. With a full storage tank of treated water, at the average usage rate for the peak month of 0.68 MGD, the system has (1.0/0.68) x 24 = 35 hours of water available, should a pump breakdown or power failure occur. Considering this conclusion and the aforementioned lack of clearwell contact time for disinfection, it appears that consideration of a new, external clearwell with standby pumping capability and an emergency power supply is appropriate for the existing water treatment plant. Solids Handlinll 22