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Plan of Study for City of North Olmsted Phase I by Floyd Browne Group January 4, 2006 2. Consider installing additional storage at the Clague Park Equalization Basin. 3. Install a shallower relief sewer to transport high flows by gravity to a newly constructed Equalization Basin in Clague Park. This would avoid possible replacement of the Walter Road Trunk Sewer and avoid rock excavation costs. 4. Assess a program of equalization tanks (EQ) to store and treat the excess storm/sanitary flows. Pump Stations: Conduct more research and testing on some of the causes of low pumping capacity at the eight-foot wet well level. a. Vortex internal to the bell of the intake? b. Stream lines setting up low pressure zones making suction difficult until the bypass pump disturbs those stream lines and allows normal operation. c. Add cones or angle iron on fillets disturbing the flow lines to avoid using the bypass pump. d. Test the three pump operation by using clean water to increase the wet well level above eight feet to simulate a storm event. Observe what occurs at the eight foot level that may be causing the reduction in pumping capacity. Determine if the concrete platforms are an obstruction. 2. As the pump station flow is critical when three pumps are required during periods of high sanitary flow, a cost effective analysis should be performed using at least one larger capacity pump so that only two (2) pumps are required to take care of emergency situations. This applies to both the LeBern and Dover pump stations. The downstream system needs to be evaluated for available capacity. Downstream improvements may be required for this alternative. 3. Acost-effective analysis should be performed by studying the increase of pump capacity vs. removal of I/I from the system by a foundation drain/sump pump program or by EQ basins to store, pump and treat. Theoretically, with an EQ tank installed, no pump station improvements should be required. Typically, pump station improvements at the LeBern or Dover locations will be expensive and may not be cost-effective as a Transport Store & Treat option. 4. Other economic analysis studies should be used to compare the following: a. An upgrade of the wet wells by removing fillets and bar screens to restore the flow of three pumps and increase the wet well storage capacity. b. Installation of an EQ tank that is filled from the by-pass pump at the stations when the level in the wet well exceeds acceptable limits. c. Constructing a second wet well to increase capacity and maintain isolation for maintenance. 5. Any work that is performed on the wet well should include a change in the suction bell diameter. This should be at least 1.33 feet in diameter. 6