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~i i ~~ r~ _1 ~~ `- ~- :. 1 t J _~ of the wetland (existing channel) that currently functions in storm water runoff conveyance. Table 1 Pond Treatment Efficiency Pond System Contributing Area TSS TP Removal Wetland Treated Removal Im act Proposed 3-Pond 126 acres 81% 52% 0.91 acres System Reduced 1-Pond 116 acres 66% 37% 0.00 acres S stem NURP Standards 90% 60% Note: The 1-pond system is shown here for comparative purposes only and is not a project alternative considered by the City of Roseville. NURP Standards are presented to demonstrate the removal efficiency goals. 3.0 Project Alternatives 3.1 No-build Alternative Realignment and reconstruction of South Owasso Boulevard will result in filling a portion of a small, isolated wetland in the southwest quadrant of South Owasso Boulevard and Matilda Street. The no-build alternative for this project would either avoid reconstruction of the roadway in this segment or reconstruct the roadway in it's current location and configuration. The No Build alternative would not include construction of any of the proposed water quality improvement facilities. Instead, the existing outlets would remain in their existing locations and the connections made across the new roadway. This alternative would avoid all impacts to wetland habitat in the project area. However, it would not provide any access or pedestrian safety improvements in the area. It would also not provide any water quality improvement for urban runoff discharged. to the wetland area and to Lake Owasso. 3.2 Other Alternatives Considered i~ e 3.2.1 Roadway and Trail Alternatives -' As originally designed, the roadway and trail construction was shown to impact approximately 2,100 square feet of the wetland basin in the southwest quadrant of South Owasso Boulevard and Matilda Street. The potential to avoid these impacts was assessed with respect to the roadway alignment and the adjacent trail. The roadway realignment cannot avoid impacts to the wetland because of the proximity of the basin to the existing roadway, changes in elevation. of the new roadway after necessary soil corrections, the State Aid requirements of the roadway design, and the intersection requirements at Matilda Street. Avoidance and minimization of impacts from the trail in this area were also assessed. Moving the trail to the south side of the basin does not avoid impacts to the basin, but only move the impacts from the northern margin of the basin to the western side. This is because the realigned trail must be - designed to appropriate standards that require a curve radius that cannot both Wetland Permit Application A-ROSEV0501.00 - South Owasso Boulevard Water Quality Improvements Page 9