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Arizona Electric Power Cooperative, Inc. (AEPCO) and Tucson Electric Power (TEP) are planning new electrical infrastructure to serve the town of Marana, Arizona and the surrounding area.
The Saguaro to Marana Project planning process is being conducted for AEPCO to construct a new 115 kilovolt (kV) transmission line between the planned Trico Electric Cooperative Inc. Adonis Substation and the existing Marana Substation. The Project will connect to the existing Saguaro Substation located approximately 7 miles northwest of Marana using an existing transmission line. TEP has identified the need for a new 138kV substation within the town of Marana. TEP will need a 138kV transmission line to provide power to this substation.
The Project will increase electric reliability and serve customers’ growing energy needs, as well as add transmission
capacity to support the development of future energy generation projects.
In today’s world, electricity is manufactured in many ways, from large-scale remote power plants all the way to local small-scale renewable energy sources. However, the bulk of electricity, no matter where it is generated, travels over long distances through a system of transmission and distribution lines that carry the electricity to where it is needed and substations that convert the voltage to an amount usable by a specific customer. This diagram gives an approximation of the path that electricity takes between where it is manufactured and a typical customer. This project primarily consists of siting new 115kV transmission lines shown circled in blue on the diagrams below.
Steel monopole (single pole) structures are typically used for new 115kV transmission lines but may include a variety of structure types, ranging in height from approximately 65 feet to 95 feet tall depending on routing, terrain, and crossing of existing structures, including elevated roads, riverbeds, and other transmission lines. The typical rights-of-way or easements will be approximately 100 to 120 feet wide. Any opportunity to utilize existing transmission line routes for the new 115kV structures will be considered.
AEPCO has been evaluating the need for this project for the last 18 months. There have been several engineering and environmental technical studies completed for the project to determine the type of facilities needed and the general area where the facilities will be located. The planning process being conducted now will take approximately 6 to 12 months and will be completed in sequential steps as illustrated in the schedule diagram below.
AEPCO considers several factors in detail prior to making decisions related to constructing and operating new transmission lines and substations. There are detailed engineering and environmental studies that are completed during the planning process. Throughout the planning process, AEPCO will also collect input from key agencies and the public (e.g., landowners, residents, business owners, etc.) prior to selecting final locations for the proposed facilities. The information provided below will help the community understand the important data that will be evaluated during the planning process.
To determine the criteria locations, we first identified the landowners, jurisdictions, and agencies within the Project study area to determine existing and planned land use and jurisdictional planning guidelines. Cities, towns, and counties in the study area typically have long-term plans that consider potential expansion of their current jurisdictional boundaries. These broader jurisdictional planning areas are reflected in officially adopted General Plans or Comprehensive Plans and identify desired future land use plans including residential, commercial, industrial, recreations, educational, etc. uses that are to be considered for development within the community. These jurisdictional planning areas are important to consider when planning new electrical infrastructure such as the proposed 115kV transmission lines. The following map shows the land ownership and jurisdictional boundaries within the study area.
Multiple studies have been conducted to help us identify areas that better lend themselves to accommodate this transmission line (opportunities), and locations that would be less accommodating for the transmission line (constraints). The criteria shown in the Opportunities and Constraints chart helps us identify route opportunities for the construction, operation, and maintenance of the new 115kV transmission lines and minimize impacts of the line to residences or other sensitive areas. For example, an arterial roadway would be considered a high-ranking opportunity to locate the new transmission line. However, that same arterial road would rank lower in a residential community (an area of high constraint) than it would within a commercial zone (an area of moderate constraint). The criteria used in identifying locations of opportunity and constraints include the following:
Existing and planned land use and visual resources data were used to identify areas that are most suitable for construction of the proposed 115kV transmission lines. The map below illustrates a composite of all the opportunities and constraints within the Project study area. Opportunity areas including following existing transmission lines and major roadways are shown in blue. Areas with low sensitivity including industrial or undeveloped areas are shown in green, areas with moderate sensitivity such as commercial areas or business parks are shown in yellow, and areas with high sensitivity such as residential areas are shown in red. This initial analysis helped determine:
The opportunity alignments along existing transmission lines and major roadways were evaluated with respect to the constraints associated with the underlying existing and planned land uses to identify preliminary alternatives for routing the proposed transmission lines. Additional siting considerations including constructability, engineering, and other technical factors were also evaluated. This map shows several preliminary alternative links that could be used to create routes that will connect the substations needed to serve customers. During the planning process, preliminary alternative links were considered, and a proposed route is being advanced based upon the route study and comments received from agencies and the public.
AEPCO has identified a proposed route from the options shown on the map above. You can view the proposed route on the map below as well as the Interactive Map.
The following Interactive Map uses geographic information system (GIS) technology to allow the agencies and public to view the project interactively. The proposed route, each of the previously considered preliminary alternative links, and the study area can be viewed on aerial imagery illustrating the existing landscape in the area. Please note, all alternatives and the proposed route are only conceptual and do not represent final locations or design.
When siting new electrical facilities, AEPCO strives to:
Numerous considerations are in play when siting electrical facilities, as identified below.
AEPCO has been conducting extensive agency and public outreach for all of its major transmission line and substation projects for more than two decades. Input from the agencies and public is critical to the success of each new project we propose to construct and operate to serve our customers. There is additional information on the FAQ page. You are welcome to contact the project team with any comments and questions using the “Contact Us” button below.
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