2009-04-28_PWETC_AgendaPacket - Laserfiche WebLink

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84 C. Area 3: South Owasso Slvd {Ladyslipper Park) 85 As a part of the 2006 S. Owasso Blvd Reconstruction project, the City completed the 86 improvements to the stone water runoff being discharged into Ladyslipper Park. 87 Between Rice Street and Western Avenue, approximately 160 acres of single family 88 residential property drain into Lake Owasso through a drainage ditch that cuts through 89 Ladyslipper Park in a north south direction. This ditch was constructed in 1971 as a 90 canoe access to Lake Owasso. In the 1991 Lake Owasso Survey report, it was 91 determined that the removal efficiency of this system is very limited: Only 30 to 50% of 92 suspended solids and 9% of the total phosphorus were removed before being discharged 93 into Lake Owasso. 94 Action to date: 95 In 2005, the City constructed a two cell. pond system north of the road as well as 3 96 wetland/ biofiltration basins south of the road. These basins increased the TSS removal 97 to 81 % and Phosphorus removal to 52%. This is a significant improvement to this 98 subwatershed area. Staff had committed to the DNR and property owners surrounding 99 Ladyslipper Park that additional wetland plantings would occur in anal around these 100 basins; however, we wanted to be assured that they functioned according to design prior 1 Ol to completing the installation. 102 Recommended 2009 action: 103 The 3 wetlandl biofiltration basins south of the road were monitored in 2006, 2007, and 104 2008 to establish water levels. Staff is satisfied that they are performing as designed. 105 However after an inventory of existing vegetation last summer it was determined that a 106 more extensive planting plan does not need to be implemented. Staff will continue to 107 monitor these basins. 108 D. Area 4i Gluek Lane Pond. and Fairview Avenue at the TH 36 Overpass. 109 During intense storm events, street flooding occurs in the residential area near the Gluek 110 Lane Pond, and on Fairview Avenue beneath the TH 36 overpass. Both areas are 111 tributary to the same storm sewer trunk system that drains north to the pond at the SE 112 comer of Fairview and County Road C {OP-1 B}. This trunk system serves 308 acres of 113 predominantly commercial/industrial land use. 114 An analysis of the- existing trunk system indicated that during a 100- yr rainfall event (6- 115 inch/ 24-hr}, Gluek Lane experiences some street flooding and the TH 36 underpass is 116 flooded to a 4.6 foot depth: This is the result of the trunk storm sewer line located in 117 Fairview Avenue being undersized, causing backflow and surcharging in these areas. 118 The CSWMP evaluated 4 options in an effort to resolve the problems identified above. 119 Option 1: Expansion of Pond OP-1A: this option would increase the holding capacity of 120 the basin located in the backyards of the homes on Gluek Lane. This option would 121 eliminate the street flooding on Gluek Lane, and reduce the flooding at the 122 Fairview/TH36 underpass to 4.2 feet. Estimated cost: $b31,318. 123 Option 2: Ponding upstream of Point A. This option would create 4.8 acre-feet of 124 storage in a pond at the SE corner of Fairview and TH 36, increasing capacity for this City of Roseville 2008 Storm Water Annual Report Page 4 of 14