09/02/2008 Council Packet - Laserfiche WebLink

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• Resource Management Recommendations • • The resource management recommendations for Planning District 5 are shown on Figure 10 -12. The specific resource management recommendation for Peltier, Hardwood Creek, and Upper Rice Creek RMUs follows. Peltier RMU Existing Conditions Recommendations • There are scattered pockets of upland all along the western boundary of this subwatershed. Each of these is currently non -urban land use. Some of this land consists of hydric soils and drained wetland. If this area becomes urban, the nonhydric soil upland area must employ infiltration BMPs, and the hydric soil areas will need to employ small site storage and biofiltration to avoid discharges to the lake. RMP Future Conditions Recommendations: • The Peltier RMU is primarily served by the existing agricultural drain tile system 72. Future development could result in significant increases in volume without proper volume reduction measures. The tile system has a small fixed capacity, therefore volume reduction measures will need to be taken within proposed developments to ensure that flooding does not occur onsite or upstream. Conversion of the tiles to an open channel and biofiltration system and buffered as a greenway corridor will more effectively serve future land use conditions. A large flow- through wetland system has been evaluated and is feasible for replacing the tile system. The storage within these systems will need to be sized to retain development runoff volumes and allow for storage and evapotranspiration while the system is slowly drawn down by the tile system. There is about 620 feet of tile west of 20th Avenue North that is still clay. It is recommended that this clay tile, about 100 years old, be examined for functionality. The city could then consider replacing it as part of a city infrastructure project, using what is most feasible for the expected future upstream flows in the subwatershed and assuming flows will be routed into the downstream and adjacent storm sewer pipe. Transferring this ditch and tile system to the City of Lino Lakes is also a reasonable consideration that would require using the state drainage law 103E abandonment proceedings and hearing. • Additional volume reductions above the RMP standard will be needed to protect certain wetlands from stormwater impacts. Hardwood Creek RMU Existing Conditions Recommendations: • Hardwood Creek flows through a diverse wetland complex on the fringe of Peltier Lake. The wetland and creek should be examined to determine the extent of hydrologic interaction between the wetland and the creek, restoring the interaction if needed, and increasing the functioning of the wetland for downstream water quality protection. • Land use planning should ensure that the existing culvert crossings will function under future conditions. In part, this requires maintaining existing runoff levels in this RMU that affect those crossings. This also requires that upstream flows from Hardwood Creek be maintained. 10 -29