9425 18TH AVE W 2018-01-01 MF Import

CMI Homebuilder's Inc. Wetland Delineation and augmentation is intended to replicate a more natural condition following construction of the pmposed condominium project. Harmsen Ergineering has provided caiculations from the three developed basins on the site. Developed Basin 1(located at the southwest corner of the site) will discharge rooftop water f�om buildings 1-4, as well as the frontage street and entry road. Stormwater from the frontage street and entry road will first pass tnrough an oillwater separator and sediment vault before being released to the infiltration trench. Flows for the 2-year storm event are 0.09 cfs. Developed Basin 5(located at the southeast edge of the site) will discharge rooftop water from buildings 5, 6, 7, 14, and 15. Flows for the 2-year storm event are 0.05 cfs. Developed Basin 6(located at the northeast edge of the created wetland area) will discharge rooftop water from buildings 25, 26, 28, 29, 30, and 31. Flows for the 2-year storm event are 0.06 cfs. In addition to this, Wetiand A will aiso be hydrologically supported through the discharge of treated stormwater to an infiltration/dispersion trench located at the wetland edge (see Sheet W1.0). The infiltration/dispersion trench will evenly distribute ths water into the wetland by non- erosive means. AII site runoff will be directed to this trench after previous detention and treatment (as required). The civil plans cleariy depict locations of the stormwater vauit and infiltration/dispersion trenches. The created wetland will be graded to create a series of small ponded areas to "stair step" down the shallow sloping hill to the existing ditch in the northem portion of Wetland A. The mitigation wetland will be graded in the summer and planted in the late fall. 7.2 Plantings The plant species used in the mitigation plan (Sheet W3.0) were chosen for a variety oF qualities, including: adaptation to specific water regimes, value to wildlife, value as a physical or visual barrier, size, pattem of growth (structural diversity), and aesthetic value. Native tree, shrub, and herbaceous species were chosen to increase both the structural and species diversity of the wetland/stream buffer areas, thereby increasing the area's value to wildlife for food and cover. Species of veg�tation that are both beneficial to wildlife and unfriendly to humans will be used in areas where human exclusion is desired. Plant materials will consist of a combination of bare-root specimens, balled and burlaped plants, and container plants. 7.3 Habitat Features Snags, stumps, and down logs will be incorporated into the mitigation area to provide ecologically important habitat features. These habitat features will be relocated from areas on the project site that will be cleared for development. Snags provide both perching and nesting sites for a variety of native birds. Cavity nesting bird species, such as chickadees and woodpeckers could bz expected to utilize such features. Down logs provide the slow release of nutrients as the wood decays, and also provide cover for amphibians, small mammals, and other wildiife. Other structures to be installed for fuifher enhancement of wildlife habitat value include bird nesting and bat roosting boxes. 7.4 Irrigation Newly installed plant material shall be irrigated for a minimum of two years following installation. The Maintenance Contractor shall water either by :�and, a water truck, or wiih a temporary aboveground irrigation system from June 15 through October 15. During the first year after 20 May 2003 Talasaea Consuliants, LLC 364C-MilRpt4(20May�3).doc Page6 J��