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Transmission lines in the southern part of Columbia are being built to reliably deliver electricity to this area and meet federal standards. This project involves adding transmission lines to connect the new Millcreek substation on Peach Tree Drive with some of the existing substations.
Spring 2015 Update: The Columbia Water & Light electrical transmission line route study is underway. This part of the project includes determining where the transmission lines will be placed, where the electric distribution lines will be buried, open houses with the public and reports to the City Council. Even though actual transmission line placement and construction will not happen until 2017, preparatory work is being done along the route.
Routine surveying has been taking place and soil sample testing is underway to determine soil characteristics. Soil testing is a geotechnical engineering test to determine soil characteristics (clay or rock, for example) and stability of the subsurface layers of soil before reaching the rock bed. Most soil tests are obtained by using a slim probe for shallow testing, or a tower-type drill rig that is attached to the back of a construction truck for deeper, rock-bed type testing. There may be excess dirt as part of this process that will be raked, shoveled or vacuumed. In the event a truck would need to be parked on personal property to conduct a test in the public easement or right-of-way area, the property owner will be contacted ahead of time.
Pole placement along the route has not been determined yet, and won’t occur until late 2015. Results of the surveying and soil testing will aid in the decision process about the placement and design of transmission poles and lines. There are a number of factors taken into consideration before a decision can be made, including:
Pole placement and design recommendations will be shared with the community and the City Council later in 2015. Look for an Open House announcement this summer.
QUESTIONS? Electric Transmission Project information line 844-244-7870 (toll free)
Download the presentation in a pdf file: July 15, 2013 City Council meeting
Option A was selected by the City Council as the route for the new transmission lines. The intent of the Option A alignment study is to connect 161 kilovolt circuits to the Mill Creek substation from the Grindstone, Perche Creek, and McBaine substations. The route will run along Providence, Grindstone/Nifong/Vawter School Road and Scott Boulevard. Columbia Water & Light is working on the final line design which will provide more details on which side of the road the lines will be located.
memo about Option A that went to Council on April 18, 2011
To handle electric load growth in southern Columbia and for reliability purposes. There is a growing need for more electricity on the southern side of Columbia. Substations in the area are approaching their maximum capacity both electrically and physically. This makes them vulnerable to being overloaded which could cause power outages and damage to other equipment in the system.
Transmission systems need to be built so one outage will not cause overloading of another transmission line. If there are two outages, the system must be built so there are not cascading outages. A new substation and transmission lines in Columbia will reduce the loading on the existing substations, ensure greater electric reliability and will improve regional stability for the power grid.
Electricity is generated at a power station or power plant from fossil fuels or renewable resources. Approximately 90% of Columbia's energy comes from sources outside the city. Once the power is generated, it has to be moved to where it is going to be used. Large amounts of power are transferred with electric transmission lines. An interconnected network of transmission lines are commonly referred to as the power grid.
Transmission lines feed into substations where transformers step down the power to lower voltages. From there, power is delivered to individual electric customers by distribution lines. New distribution lines in Columbia must be placed underground according to city ordinances. In the older sections of town, distribution lines are mounted on wooden poles.
Electrical power delivery systems are built with an interconnected network of transmission and distribution lines. That way if there is a problem with one section of an electric line, operators can switch the flow and provide electricity to customers with another line. An interconnected electric grid helps the reliability of the system and can greatly reduce the length of an outage
The Columbia City Council decided to build the new transmission lines overhead. Due to the high voltage of the electricity the lines carry, it is much more involved to bury them than it is distribution lines. Transmission lines are not frequently buried in the United States due to the cost. Placing transmission lines underground in Columbia is estimated to cost $7.6 million per mile versus $1.1 million per mile for overhead construction. The estimated rate impact per customer to build the lines underground would be $8.26 per month for 20 years versus $1.18 for overhead.
Electric and Magnetic Fields (EMF) are generated by the flow of electrons. Electric fields are established between points of different voltages. Magnetic fields are generated by electrons flowing in a conductor. EMF are generated by electric lines as well as many common household items.
According to the Environmental Protection Agency, “Much of the research about power lines and potential health effects is inconclusive. Despite more than two decades of research to determine whether elevated EMF exposure, principally to magnetic fields, is related to an increased risk of childhood leukemia, there is still no definitive answer. The general scientific consensus is that, thus far, the evidence available is weak and is not sufficient to establish a definitive cause-effect relationship.
Please see these web sites for more information about EMF and any possible health issues:
Environmental Protection Agency - (1 page overview with links)
Electric Power Research Institute – general overview and list of resources on EMF (5 pages)
Electric Power Research Institute - answers to frequently asked questions about EMF (2 pages)
Western Area Power Association – provides a basic overview of EMF and levels of EMF found in power lines (16 pages)
Download a historical time line of this project.
Sega, Inc. was hired by the city to evaluate different transmission line routes to start the public discussion. The consultants divided the project into three different sections and proposed three to four different routes for each section. The initial routes were chosen using these criteria:
After the initial routes were selected, they were presented to the public and the City Council. Written public comment was tabulated to formulate a selection matrix for each route. Columbia Water & Light collected feedback during late 2012/early 2013 to determine the public's most favorable route and the preference for building overhead or underground electric transmission lines. Click here for a historical time line of the project.
The intent of the alternatives in the Option B alignment study is to connect the Mill Creek substation with 69 kilovolt lines along the existing 69 kilovolt line route from the Grindstone substation to the Hinkson Creek substation. Option B will place the Mill Creek substation in series with the 69 kilovolt circuit from Grindstone to Hinkson Creek substations. In addition, Option B connects the McBaine substation to the Perche Creek substation via a 161 kilovolt line routed along the southwestern periphery of the city limits as Council suggested. Public feedback was used for the evaluation matrix to determine the preferred routes for Option B.
After the publicly preferred route for Option B was identified, Columbia Water & Light staff looked into the possibility of moving a section of the line to city owned property near the Waste Water Treatment Plant, the city’s wetland cells and the Water Treatment Plant. These properties also contain a section of the MKT trail. Option B-2 was presented to the City Council in August 2012 and at a public meeting in November.
Option B map - publicly preferred route
Option B-2 map - publicly preferred route
Report to the City Council on 8-20-12: Millcreek Substation Transmission Study - Option B