Orono Substation Expansion - Enviromental Assessment (1)

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Construction equipment typically used on a transmission project would include tree removal equipment,mowers,cranes,backhoes,digger-derrick line trucks,track-mounted drill rigs,dump trucks, front end loaders,bucket trucks,bulldozers, flatbed tractor-trailers, flatbed trucks,pickup trucks,concrete trucks and various trailers. Transmission line structures are generally designed for installation at existing grades. However, along areas with more than 10 percent slope,working areas may have to be graded level or fill would be brought in to create working pads. If the landowner permits,Xcel Energy prefers to leave the leveled working pads in place for future maintenance activities,as necessary. If the landowner does not agree,Xcel Energy will grade the site back to its original condition and any imported fill is removed from the area. Typically existing roads or trails that run parallel or perpendicular to the proposed route are used to access the actual transmission line right-of-way. Where use of private field roads or trails is necessary,permission from the property owner would be obtained by Xcel Energy prior to access. In some cases,new access roads or temporary lay down areas may be required due to problematic structure locations,when no current access is available,or existing access is inadequate for the heavy equipment used in construction. Should these areas fall outside the right-of-way,temporary easements would be arranged with the affected landowner. These temporary easements are not typically part of the route permit issued by the Commission for high-voltage transmission lines. Staging areas are often established for a project to provide a location to deliver and store materials required for construction. Xcel Energy anticipates using the Orono Substation site or other nearby Xcel Energy substation sites as staging areas for the Project. If needed,additional temporary staging areas outside the transmission line right-of-way or at non-Xcel Energy sites will be obtained through rental agreements. Transmission line structures are typically delivered to their staked location or to a designated staging area depending on delivery and contractor availability. If the poles are delivered to a staked site,they are typically designed for the specific site location at which they are to be constructed and are placed along the right-of-way out of the clear zone of any adjacent highways or designed pathways and marked for visibility. One of the structures is considered to be a"tangent" structure,or in a straight line with both its adjacent structures. Xcel Energy anticipates that this structure would be direct embedded. Direct embedding would generally require an excavation of a three to four foot diameter hole at least 15 feet deep or greater,depending on soil conditions and other factors. The poles are typically framed with insulators and hardware on the ground and then lifted and placed in the hole via a bucket truck or a crane,depending on the weight of the structure. The poles would be backfilled with native soils or crushed rock depending on soil and design conditions. In lowland areas,a galvanized steel culvert may be also inserted for pole stability due to poor soil capacity. Any excess soil would be thin spread or removed from the site as required. Seven of the eight proposed structures for the Project are angle structures and would be set on drilled pier concrete foundations to support the higher stress. The drilled pier would typically have a diameter of six to eight feet and typically require an excavation depth of approximately 25 feet, depending on soil conditions and design requirements. The excavation is filled with concrete and a concrete foundation is set,the pole or structure is then bolted to the foundation. Environmental Assessment 1 PUC Docket E002/IL-11-223 Page 16 1