THORNTON SUBSTATION. Why is the substation needed? How were the three potential sites identified?

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1 THORNTON SUBSTATION Xcel Energy has been working for seven years to identify a new site on which to build a new electrical power substation. If approved by City Council, this will be the first substation to be built in Thornton since 1992 more than two decades ago. Without a new substation, Thornton businesses and residents are at high risk for service interruptions similar to the five-hour power outage in the summer of Why is the substation needed? Thornton s population has doubled over the last 25 years, with new residents flocking to the area for its reasonable cost of living, local recreational offerings, and proximity to Denver and the Rocky Mountains. This growth has also led to the development of new retailers and commercial centers. And soon, RTD will add a new commuter rail line to the area. This rapid pace of expansion puts ever-increasing demand on the power grid supplying electricity to a growing community. If approved, the substation will: Provide critical, reliable power to Thornton residences, businesses and community facilities, such as schools and hospitals. The substation will reduce the area s risk for extended outages that could disrupt residents everyday lives. Be constructed with underground power lines, as approved by the Colorado Public Utilities Commission (CPUC). Who is the Colorado Public Utilities Commission, and what is their role in the Thornton Substation Project? The CPUC is a division of the Colorado Department of Regulatory Agencies, and Xcel Energy s regulator. Its purpose is to assure the availability of safe, reliable, adequate and efficient electric, gas, steam and water services to utility customers. By granting a Certificate of Public Convenience and Necessity (CPCN) to the Project, the CPUC concluded that a new substation is a needed addition to the Thornton community to support current and future growth, and that existing facilities are inadequate to deliver the expected future load increases in the area the substation will serve. Be designed with neighbors in mind. Xcel Comply with the Colorado CPUC Certificate of Public Convenience and Necessity. In April 2015, Energy will incorporate landscaping, an architectural wall, and other community suggestions to ensure a cohesive design. the CPUC granted a Certificate of Public Convenience and Necessity (CPCN) to Xcel Energy for the Thornton Substation, acknowledging the current and future need for the proposed project to provide reliable power to Thornton residents and businesses. The CPUC considered the Company s proposed siting area for the substation, as shown in the map below, roughly between 120th and 136th avenues in its review and ultimate approval of the CPCN. This area was also supported by the City and ultimately led to the Commission s agreement in allowing the Company to install underground transmission lines to serve the proposed substation. How were the three potential sites identified? Xcel Siting Area Xcel Energy has identified three potential substation sites for the public to consider and comment on. Last year, Xcel Energy rolled out to the community a design for a substation located at the southeast corner of East 136th Avenue and Holly Street. We had evaluated numerous sites and determined that this site would meet electrical and land use criteria established for the project. During our outreach, we heard the community wanted more site options to consider and Xcel Energy went back to evaluate other sites and determine if there were other suitable locations within the siting area. All three sites meet the electrical need of the project and are within the siting area required to provide reliable service to Thornton.

2 Transmission Why construct the transmission line underground? We have proposed underground transmission construction because the facilities are located in areas characterized by dense residential and commercial development. There is insufficient space between existing and proposed land uses and the edge-of-road right-of-way for an overhead transmission line. The City of Thornton worked with Xcel Energy and the CPUC to help Xcel Energy get state approval to underground the transmission lines for this project. How would you construct underground transmission lines? At any of the proposed three sites, Xcel Energy is proposing to construct the transmission line under existing roadways between the substation site and the existing 115kV transmission line. In preparation for construction, the right-of-way boundaries, sensitive resources (such as waterways), and existing underground utilities are identified and marked. The process of constructing an underground transmission line under a roadway is shown below. Underground transmission lines are constructed by excavating a trench, typically 2 to 3 feet wide and a minimum of 5 to 6 feet deep. The underground transmission line will primarily be constructed in a concrete-encased duct bank system providing for safety, minimizing the potential for dig-ins, and providing for thermal dissipation. After construction, the trench is filled with native soil and the street is repaved. The duct bank will likely have two underground vaults, which are large concrete boxes buried at 2,500-foot intervals along the construction route that help splice the cables and allow permanent access for any needed maintenance and repair. The underground vaults are accessed via two manholes. Trenching Backfill/Asphalt Repair Splice Vault Manholes Splice Vault Installation Temporary Plates Installation Will construction of this line cause problems with traffic and noise? Temporary congestion and noise can be expected during construction. To minimize inconvenience and to maximize safety, Xcel Energy prepares traffic-control plans and obtains street occupancy/street cut permits as part of design and engineering. Construction activities may be restricted during certain hours or during weekends. Xcel Energy will work with the City of Thornton to identify a work schedule that advances the project safely and quickly to minimize traffic impacts, but also accounts for any work hour restrictions necessary during rush hour and near residential areas.

3 THORNTON SUBSTATION Site Options All three sites meet the electrical need of the project and are within the siting area required to provide reliable service to Thornton. Regardless of the final site selected, Xcel Energy will work with neighborhood residents, the City of Thornton, and other interested stakeholders to develop a site-appropriate design. The design of the architectural wall will use a variety of colors, materials, textures, and heights to integrate the design into the surrounding development. Landscaping, berming, and open space buffers may be used to varying degrees, depending on the size and layout of the final site. A larger site will allow more space for landscaping and other design features. Largest Site (Southeast corner of East 120th Avenue & Holly Street) Will Incorporate Architectural Wall and Underground Power Lines Vacant, Developable Land Meets Electrical Engineering Criteria (will meet customers power needs) Located Furthest from Residences Offers Greatest Distance To Nearest School or Similar Use (Library) Opportunity to Integrate with New Development Minimizes Length of Transmission Line SITE 3B 8.09 Acres 300 Feet 1,055 Feet from Glacier Peak Elementary School 1.2 Miles No 1.8 Miles 425 Feet from AnyThink Library (Northeast corner of East 120th Avenue & Bellaire Way) (Southeast corner of East 136th Avenue & Holly Street) 5.95 Acres A larger site allows for larger buffer areas between neighboring properties that could be used for landscaping, berming, or other design features. Rationale 4.66 Acres An architectural wall and underground power lines would be utilized at all three sites. All three sites are vacant, developable land that have willing sellers. was not vacant during initial siting process (occupied residences were located onsite). In April 2015, the Colorado Public Utilities Commission certified that Xcel Energy s siting area will meet the electrical needs of the project. 180 Feet 185 Feet from Lord of Life Lutheran Church and School 90 Feet from Elms Haven Center 168 Feet 1,007 Feet from Horizon High School No 1.5 Miles All three sites provide enough space such that noise and electromagnetic field (EMF) exposure at proximate residences would not exceed State requirements. Residents and the City of Thornton have expressed a preference to maximize distance from schools and community centers. At, substation site can be incorporated into retail development proposal via partnership with the new landowner. Sites 4 and 10 are surrounded by existing development. The transmission line would be located under East 120th Avenue or East 136th Avenue. A shorter transmission line means less traffic disturbance during construction. Vicinity Map Xcel Siting Area LEGEND Adams County Boundary City of Thornton Multi-Use Trail Substation Site Boundary City of Thornton Zoning Neighborhood Services Community Retail Parks and Open Space Site Name SITE 4 SITE 10

4 Substation Design What will the substation look like? Our goal is to work with neighborhood residents, the City of Thornton, and other interested stakeholders to develop a site-appropriate design. A preliminary concept shown below uses a variety of colors, materials, textures, and heights to incorporate the design into the surrounding area. These conceptual ideas will be refined further depending on the specific site selected, and the architectural and landscape character of the area surrounding that site. Xcel Energy welcomes input from the community about ways to incorporate the substation into the surrounding area. Some equipment, including the masts used to protect the equipment from lightning strikes, will extend above the wall. Equipment heights are set by the National Electrical Safety Code for safety of personnel and protection of the electric system. Setbacks from streets and adjacent land uses allow space for landscaping and berming and creating the perception of a smaller-scale facility. Interior lighting will only be used for emergency maintenance to restore power. Exterior lighting will be minimized and directed downward to prevent excessive intrusion into neighboring properties. Landscaping may include earth berming and planting a mix of deciduous and evergreen trees and shrubs for added screening and softening of views. Architectural wall will screen most of the equipment from view and will be an appropriate height within the context of the neighborhood. Open space buffers may be used to create the perception of a smaller-scale facility and provide additional separation between adjacent land uses.

5 Common Questions Are substations and transmission lines safe?. Xcel Energy makes every effort to ensure safety in construction, operation, and maintenance of all its facilities. Our practices meet or exceed standards mandated by the National Electrical Safety Code as well as those adopted by local governments. How would you respond to an on-site emergency? Emergencies are rare, but we recognize that they can happen and we plan for them accordingly. Xcel Energy substations are monitored and controlled remotely from an operations center. In the event of an outage or emergency, the equipment is instantaneously shut off and Xcel Energy personnel will respond in coordination with first responders. I have questions about... Electric and magnetic fields The CPUC also ensures that electric and magnetic fields (EMFs) meet the state s requirements. The CPUC found that the expected EMF values from the substation project, including the connecting power lines, are considered reasonable and do not need to be mitigated. The potential for EMF health effects has been studied extensively for decades. There is substantial agreement among experts that there are no adverse health impacts when substations are placed within 100 feet from homes, schools, or other organizations. For more Information about electric and magnetic fields, please visit xcelenergy.com and type EMF into the search box. Property Values Xcel Energy has consulted with third-party appraisers who completed a study of home and land values near substations in Denver, Arapahoe and Boulder counties. The results indicate there is no measurable market impact on property values because of proximity to substations. Increased Traffic The substation will be accessed from major roads in the city, typically once a week for inspections and maintenance. Other types of facilities that could be permitted in the Neighborhood Services Zone District would likely cause additional traffic, require additional lighting, and involve more noise in comparison to the substation. Sound The CPUC found that the expected audible sound values from the Thornton Substation project are considered reasonable and do not need to be mitigated. The substation will be designed, operated, and maintained so any sounds remain at or below City of Thornton and Colorado State decibel sound limitations associated with residential zone districts (Thornton Code of Ordinances (c) and Colorado Revised Statutes [CRS] et seq.). Sound from heavy machinery during construction may create a short-term nuisance during daytime hours. Construction in the City of Thornton is not permitted between the hours of 9 p.m. and 6 a.m. Next Steps Xcel Energy s goal is to have this substation in-service, and providing reliable electricity to Thornton by summer To accomplish this, we plan to submit land use permit applications to the City of Thornton for one site in Spring/Summer Between now and then, we will conduct public outreach to solicit residents input, refine a site plan, and prepare permit application materials. We look forward to working with the city and members of the community to get input on which site will work best for everyone. Project Website and Contact Information Website: xcelenergythorntonsubstation.com info@xcelenergythorntonsubstation.com Hotline: The Neighborhood Services Zone District All three potential sites are zoned as Neighborhood Services (NS) by the City of Thornton. The City s code lists the uses permitted in this District. Electric substations are permitted with a Specific Use Permit, Major Development Permit, and other construction permits. Other uses that could be permitted in the NS Zone District include oil and gas well sites or production sites, banks, offices, convenience-type stores, and food services. xcelenergy.com 2016 Xcel Energy Inc. Xcel Energy is a registered trademark of Xcel Energy Inc.Public Service Company of Colorado, an Xcel Energy Company 3/16