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Plan of Study for City of North Olmsted Phase I by Floyd Browne Group January 4, 2006 The soil type most predominant in the Dover drainage area is Mahoning- Urban land complex soils. Again, this soil is poorly drained, has a perched seasonal water table of 12-30 inches from the surface, and the permeability is slow to very slow. Run off potential of this soil is low to medium. As in the LeBern area, the soil is better suited to buildings without basements. A map of the soil types and soil surveys may be found in Appendix G. The topography tends to be flat for both drainage the LeBern and Dover drainage basins and, as indicated in the soil surveys, poorly drained. This was observed during the August 20th storm and documented by pictures taken during and immediately after the storm. These conditions have an impact upon the ability of the storm water to travel to the collection system for transport. Floyd Brown Group recommends the following concerning the LeBern and Dover drainage basin studies: Model the main drainage artery in the LeBern area to find what result should be in a 100+-year storm and compare the result to the observations during the August 20, 2005 storm. The questions to be answered from this exercise are: a. Is the flow getting away to the storm collection system? b. Is the storm water showing a temporary high water table on top of the rock base and getting into the residents basements to be carried away by the foundation drains, yard drains, and sump pumps, which may be connected to the sanitary system. If the flow is not getting away and the water is gaining entrance to the sanitary system through foundation drains and sump pumps, this may be a major component to the sanitary sewer overflow situation in North Olmsted. It may also be an answer to some of the observations of high flows in the sanitary sewer with medium to low flows being observed in the storm sewers. 2. A study of the economy of a solution to large amounts of storm water entering the sanitary sewers may include: a. Assess the older portions of the City where it is known that a high percentage of homes have foundation drains tied into the sanitary sewers and initiating a program of sump pump installation to rid the sanitary of storm influence through foundation drains. b. Assess a program of EQ tanks to store and treat the excess storm/sanitary flows areas conducive to the system such as Clague Park. 3. An evaluation of the local storm sewer collection and transport infrastructure should be performed.' a. From the residential home inspection study it appears that storm water collects around the home foundation and cannot find its way to the storm collection system. This water eventually finds its way into the sanitary sewers. 22