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134 An analysis of the existing trunk system indicated that during a 100- yr rainfall event (6- <br />135 inch/ 24-hr), Gluek Lane experiences some street flooding and the TH 36 underpass is <br />136 flooded to a 4.6 foot depth. This is the result of tl~e trunk storm sewer line located in <br />137 Fairview Avenue being undersized, causing backflow aztd surcharging in these areas. <br />138 <br />139 The CSWMP evaluated 4 aptions in an effort to resolve the problems identified above. <br />140 <br />141 Option 1: Expansion of Pond OP-1 A: this option would increase the holding capacity of <br />142 the basin located in the backyards of the homes on Gluek Lane. This option would <br />143 eliminate the street flooding on Gluek Lane, and reduce the flooding at the <br />144 Fairview/TH36 underpass to 4.2 feet. Estimated cost: $631,318. <br />145 <br />146 Option 2: Parading upstream of Point A. This option would create 4.8 acre-feet of <br />147 storage in a pond at the SE corner of Fairview and TH 36, increasing capacity for this <br />148 subwatershed. Flooding at Fairview would be reduced to 3.3 feet. Estimated cost: <br />149 $156,000. <br />150 <br />151 Option 3: Provide aggressive rate control for the Rosedale Mall site. <br />152 This option assumes a 40% reduction in peak flow from the Rosedale Mall site. It also <br />153 assunrzes that options 1 & 2 are implemented. Eslizxzated Cost = $787,318 + costs far <br />154 Rosedale improvements. <br />155 <br />156 Option 4: Construct a new storm sewer irurtk Tine along Fairview Avenue. This option <br />157 includes the construction and reconfiguration of the Fairview trunk storm sewer. It <br />158 eliminates flooding under TH 36 and on Gluck Lane; however, it pushes the water <br />159 downstream to the pond in the SE corner of Fairview and C, increasing the high water <br />160 elevation by 1.3 feet. Estimated cost: $1,935,000. <br />161 <br />162 Action to date: <br />163 The only option discussed in the CSWMP that addressed the street flooding issues <br />164 completely was Option 4. However, due to potential impacts to the homes located <br />165 around the pond in the $E cnnler of Fairview and County Road C, staff does not feel that <br />166 this option is feasible. After a 6-inch rainfall event that occurred 1 01412 0 0 5, we <br />167 experienced localized flooding in a number of different areas around the City. The home <br />168 at 1779 Rose Place was flooded during this extreme rain event. <br />169 <br />170 Due to the cost, limited benefit, and potential izxzpacts to the properties located around the <br />171 pond at Fairview and County Road C, staff does not recommend proceeding with any of <br />172 the options as described in the CSWMP. <br />173 <br />174 Recommended 2048 action: <br />175 in an effort to address some of the flooding concerns in this problem area, staff will <br />176 cozatinue to require redevelopme~zt projects to reduce the volume of water that is sent to <br />177 this system. This is similar to the action described in. Option 3. A reduction in the peals <br />178 flow from the commercial properties located in the subwatershed will alleviate the <br />179 demand on the Fairview trunk sewer. <br />............... <br />City of Roseville <br />2007 Storacn Water Annual Report Page 5 of 1S <br />