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drainage ditch that cuts through the park in a north south direction conveying ro- storm water runoff northerly to Lake Owasso. This ditch was constructed in 1971, as a canoe access to Lake Owasso. In the 1991 Lake Owasso Survey - report, it was determined that the removal efficiency of this system is very limited. Only 30% to 50% of suspended solids and 9% of the total phosphorus were removed by the wetland before being discharged into Lake '1 Owasso. This subwatershed is the largest remaining untreated direct T discharge of stormwater into Lake Owasso. The GLWMO as well as the City of Roseville, have included the reduction of sediment and phosphorus - loading in Lake Owasso as a primary goal in their comprehensive storm. water management plans. 2.0 Project. Description The proposed project includes reconstruction of South Owasso Boulevard. from Dale Street to Rice Street (Figure 1). Only that segment between ~ Marion Street and Matilda Street (Figure 2) will be realigned to reduce traffic speed, provide on street parking to serve the adjacent City park on both sides °-' of the roadway and to improve the safety of pedestrian movements along and across the roadway. This Wetland Permit Application refers only to the roadway realignment and water quality improvements in the segment between Marion Street and Matilda Street (Figure 2) because this is the only segment having potential to impact wetlands. r` The roadway will be realigned to curve south between Marion and Matilda streets as shown on Figure 4. An eight-foot bituminous pathway will be constructed along the south side of the roadway. On street parking will be provided along the north side of the roadway in two separate locations. The northern portion of the roadway will be constructed with curb and gutter. The southern portion of the roadway will be constructed as a rural section to allow roadway runoff to reach the rain garden features as shown on Figure 4. A small, isolated wetland basin immediately west of Matilda Street and south of South Owasso Boulevard will be impacted by the realignment of the roadway and by construction of the adjacent pathway. The associated water quality improvements include construction of three stormwater treatment ponds and two rain gardens. The rain gardens will provide treatment of runoff from the southern half of the roadway and will discharge to the proposed stormwater treatment pond system prior to discharge into wetland. Construction of the treatment ponds will result in direct impacts to wetlands on the north side of South Owasso Boulevard. The rain gardens are proposed to be located in upland areas south of the realigned roadway. 'i he proposed ponds include three cells. Cell 1 is located on the bed of the existing roadway, within the curve of the realignment (Figure 4). This first cell is located completely outside of wetland habitat and has been designed to use upland area between the realigned roadway and the existing wetland for pretreatment prior to discharge into the adjacent wetland area. Cell 1 will provide pre-treatment of runoff from the 104-acre contributing area that currently discharges at Galtier Street. This first cell will provide pretreatment of runoff from the majority of the contributing watershed area to the south prior to discharge into the other proposed treatment cell and the adjacent Wetland Permit Application A-ROSEV0501.00 South Owasso Boulevard Water Quality Improvements Page 7