Environmental Assis for Orono Substation Expansion

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Using information from the wetland delineation of the substation site, Xcel Energy has designed the substation to avoid direct impacts to wetlands from the substation. Following the issuance of a route permit Xcel Energy will perform a wetland delineation along the route to determine wetland locations and minimize impacts from the Project. Standard erosion control measures identified in the MPCA Stormwater BMP Manual, such as using silt fencing to minimize impacts on adjacent water resources would be followed (Xcel Energy, 2011a). Practices may include containing excavated material, protecting exposed soil, and stabilizing restored soil. In its route permit application, Xcel Energy has proposed the following mitigation measures: • Spanning wetlands to the greatest extent possible; • Assembling structures on upland areas before they are brought to the site for installation; • Avoid crossing wetlands with construction equipment to the extent possible; • Construction during frozen ground conditions in wetlands to the extent possible; • Construction crews will attempt to access the wetland with the least amount of physical impact to the wetland (i.e., shortest route) and will access poles near or in wetlands from roadways whenever possible to minimize travel through wetland areas; • When construction during winter is not possible, construction mats (wooden mats or a composite mat system) would be used to protect wetland vegetation; and • Use of standard erosion control measures identified in the MPCA Stormwater BMP Manual, such as suing silt fencing to minimize impacts on adjacent water resources. (Xcel Energy, 2011 a) Additional mitigation measures could include: • No staging or stringing set up areas will be placed within or adjacent to wetlands or water resources, as practicable. • Restoration of wetland vegetation as soon as possible following construction. 5.14 Flora The proposed project is located in the Big Woods Subsection of the Eastern Broadleaf Forest Ecological Province of Minnesota (MnDNR, 2011a). At the time of European settlement, this subsection was characterized by large blocks of oak woodland and maple-bassleaf forest. Land use along the routes reviewed in this document is predominated by residential uses, which incorporates a large block of undeveloped association land, wetlands, and the Baker Park Reserve, which contains a remnant of the pre -settlement Big Woods vegetation. Rare or sensitive plant species and habitat are discussed in Section 5.16. The Project would directly impact to vegetation would be through tree clearing. The Xcel Energy Proposed Route would remove approximately 2.2 acres of trees; depending upon the route alignment in relation to the MnDOT ROW, the Baker Park Reserve Route Alternative remove approximately 2.0 to 2.3 acres of trees (Xcel Energy, personal communications, November 16 and 28, 2011). No impacts to identified native plant communities or sensitive plant species are anticipated. Mitigation Measures The primary mitigation strategy to minimize impacts to vegetation is minimizing the extent of tree clearing. Xcel Energy has attempted to minimize the need for tree clearing by overlapping railroad and highway easements to the extent possible. Environmental Assessment PUC Docket E002/TL-11-223 Page 49