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.:. ~. Plan of Study for City of North Olmsted Phase I by Floyd Browne Group January 4, 2006 storm system and must be connected to the sanitary sewer, but dye testing should be done to confirm this assumption. Extensive dye testing around the homes should be done in the future to determine all sources of clean water connections. Some residents have sealed the drains on their lowest floor, but still experienced flooding from the stairwell drain. In the Deerfield Estates subdivision, there was some street flooding and many swales in the rear yards did not drain properly to convey the storm water to the storm sewers in the streets. Therefore, there was considerable yard flooding that occurred and contributed to the saturated, poorly drained soils ultimately entering the foundation drain system and then the sanitary sewers. When the sanitary sewers are surcharged above the basement elevations, some basement backups occur from sanitary sewage, but the major flooding is from the storm water that comes out on the floor. In this area, basement flooding ranged from one inch to ten inches. On Maple Ridge Road, some street flooding occurred, but the basement flooding appears to be the result of surcharging the sanitary sewer on Walter Road. Many of these homes have full basements and were previously on a septic tank. Foundation drains contributed to the problem and yard flooding was reported. The clean water entering the sanitary sewer also contributes to the flooded basements. The basement flooding again ranged from one to ten-inches. Some residents believe that clean water flooded their basements and others thought that it was wastewater. However, a special situation can occur when the main line sewer is surcharged but not backing up into basements. Footer drain water (clean but mixed with some wastewater in the lateral) can come out the floor drains since it takes the path of least resistance. Another case may be that the lateral is not able to convey the large volume of footer drain water to the main line sewer due to a partial blockage in the lateral from roots, a reversed slope, etc. These observations should be further defined. Sanitary Sewer System Evaluation and Analysis The sanitary sewer system tributary to the LeBern Pump Station consists of a 12-inch diameter trunk on Clague Road and a 12-18 inch trunk on Walter Road, Beech Lane, and LeBern Drive. Most of these sewers are at minimum grades to comply with the scouring velocity requirement of two feet per second. The local sewers are 8-inch diameter with some 10-inch collector sewers. This system was installed in the 1960's to eliminate septic tanks and some small wastewater package plants as well as to provide for future development. The sewer lines are mainly vitrified clay pipe in 4-6 foot lengths. At Clague Park, there are six large diameter underground pipes with a capacity of 380,000 gallons for storing wet weather peak flows. This equalization system is filled by a small underground pump station and is drained by gravity. This Equalization Pump Station can be controlled remotely from the LeBern Pump Station to optimize the performance of the system before any by-pass pumping is necessary. The LeBern Pump Station operates on a variable frequency drive that keeps the level in the wet well constant while increasing the pumping rate as the influent flow rate increases. Normal Average Daily Flow (ADF) is approximately 1.3 million gallons per day (MGD) or 900 gallons per minute (gpm). The station can handle a peak flow of approximately 3.8 MGD or 2650 gpm when all three pumps are utilized. Based on 2200 residential equivalent units (REUs), the design flows would be an ADF of 0.88 MGD and a PDF of 2.94 MGD. Due to the poorly drained 11