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44 This analysis allowed us to evaluate the performance of the system during intense storm 45 events and determine haw incremental improvements would impact the elevation of 46 flooding within rear yards, low areas and intersections in this neighborhood. As a result 47 of this analysis, the following improvements were constructed in 20p7: 48 49 Bremler Street 50 • Runoff from the wetland on the vacant lot west of 800 Brenner was redirected to S 1 storm sewer which flows directly to Lake Owasso, allowing for additional capacity in 52 the Charlie Pond pipe. 53 Millwood Avenue S4 • Yard eatcla basins at 815 Millwood were disco~inected liom the storm sewer that 55 flows to Charlie Pond pipe and connected to the storm sewer that flows to Lalce 56 Owasso., allowing for additional capacity in the Charlie Pond pipe. 57 • Anew connection was made between the manhole in the boulevard at 820 Millwood 58 and the manhole in the boulevard of 819 Millwood. This new pipe serves as a relief 59 for high flow conditions, allowing for the low point to drain faster. 60 Avon Street 61 The existing catch basins at 3075 and 3074 Avon were replaced with larger grates and 62 an additional catch basin was constructed at 3081 Avon to increase inlet capacity. 63 64 Recanunended 2005 action: 65 The final recommendation from the drainage study was to purchase the vacant lot at 806 6b Brenner Avenue. City Council authorized staff to start negotiations on July 17, 2007. 67 We are continuing to work with the Reding trust on the acquisition of this lot. 68 69 8. Area 2- St. Rose of Lia~aa Area 70 The intersection of Dellwood and Skillman Avenue, located near St. Rose of Lima 71 Church, experie~aces street flooding during periods of intense precipitation. Runoff from 72 appraxianately 14.5 acres of residential land use is tributary to this intersection either 73 directly or via the storm sewer along Dellwood and Skillman Avenues. In addition 74 runoff from a portion of the St. Rose of Lima property is tributary via the Dellwood 7S Avenue storm sewer, adding about 5.7 acres of mostly impervious surface. 76 77 An analysis of the existing trunk system indicated it can handle a 2 year rain event. As a 78 result, during intense rainfall events, the trunk system experiences surcharge, thereby 79 causing the intersection to flood to a 1.9 foot depth. 80 81 The CSWMP recommended a two tier solution for this street flooding problem. 82 Option 1: Construct a pond in the storm water retention on the St. Rose of Lima site. The 83 site is approximately 28% of the total tributary area, and contributes 39% of the total 84 runoff volume. Just implementing this option reduces the intersection flooding to 1.6 85 feet. Estimated cost: $148,159. 86 87 Option 2: Expand the pond in Mayflower Park and construct a parallel storm sewer to 88 direct runoff from the intersection to the expanded pond. This would effectively turn this City of Roseville 2007 Storm Water Annual Report Page 3 of 15