Recent Substation Construction & Future Plans

May Street Substation

• Completed and Operating
• Location: 218 May Street - Centralia, WA
• Commissioned: March 2015
• The May Street Substation receives transmission power from both Bonneville Power Administration (BPA) and the Yelm Hydro Project. The Yelm Hydro Project is located on the Nisqually River near Yelm, WA and is capable of generating approximately 12 Megawatts (MW) of electrical power with optimum water availability and river level. On an annual basis this accounts for approximately 25 to 30% of the power needs for the City of Centralia. The May Street Substation is classified as a 69 by 115/12.5-kV distribution substation with a transformer capacity of 33 Megavolt-amps (MVA). This substation presently supplies the downtown business district, Centralia College and two elementary schools among its major loads. It is capable of interconnecting with the Cooks Hill and Zimmerman Substations. In the future, it will also interconnect with the planned Salzer Substation (2020).

Fords Prairie Substation

• Upgraded and Operating
• Location: 1800 Gallagher Road - Centralia, WA
• Re-Commissioned: October 2018
• The Fords Prairie Substation was upgraded from April through October 2018. The upgrade included the incorporation of the latest earthquake resistant design innovations. This new design includes the placement of the substation power transformer on a platform supported by special bearings. The bearings are specifically designed to allow the ground to move beneath the transformer during an earthquake event reducing the possibility of catastrophic failure of the transformer. The power-carrying buswork was also designed to minimize any damage that may result from the earth's movement. The purpose of this new design is to help the substation survive the expected Cascadia Subduction Zone (CSZ) earthquake event. The Fords Prairie Substation is classified as a 69 by 115/12.5-kV distribution substation with a transformer capacity of 43 MVA. It was built to accept a second transformer of the same size. BPA has added the switching capability for the Fords Prairie Substation to be supplied by either side of the transmission loop that serves Centralia. This substation presently supplies major loads that include Centralia High School, the new UNFI Grocery Warehouse, and other industrial loads in Phase I of the Port of Centralia. It is capable of interconnecting with the Cooks Hill, North Port and Zimmerman Substations.

New Salzer Substation

• Planned for Construction in 2019 to 2020
• Location: 201 E Summa Street - Centralia, WA
• Planned Commissioning Date: 1st Quarter 2020
• The new Salzer Substation will be located in the southeast quadrant of the City of Centralia. This area of the city is presently supplied by the May Street Substation which is approximately two miles to the north. Similar to the Fords Prairie Substation, the Salzer Substation will also be built to the latest earthquake resistant design standards to help it survive the CSZ earthquake event. This will result in one earthquake resistant substation on the west side of I-5 (Fords Prairie Substation) and one on the east (new Salzer Substation). The transformers at the Fords Prairie and Salzer Substations are identical and together they are capable of carrying the load of the city during the majority of the year in the event of an earthquake. The Salzer Substation will be classified as a 69 by 115/12.5-kV distribution substation with a transformer capacity of 43 MVA. It will be supplied by transmission power from BPA's east loop around Centralia from a tap point near where Salzer Valley Road intersects with Centralia-Alpha Road. This new substation will supply major loads that include two elementary schools, a major grocery store, a portion of the downtown business district, and commercial loads on Gold Street and Kresky Avenue. When the Centralia Station retail/commercial project is completed, it will be fed by the Salzer Substation. The Salzer Substation will be capable of backing up the power supply to the Providence Hospital Medical complex; which is normally supplied by the Cooks Hill Substation. The Salzer Substation is capable of interconnecting with the Cooks Hill and May Street Substations.

Upgrade to 115-kV

• Ongoing
• Since 2007, the City has been building new substations and upgrading existing substations because BPA is planning to upgrade the voltage of its 69-kV transmission loop, that serves the City of Centralia, to 115-kV. The timing of this upgrade depends largely on the City's load growth. Once the peak load on the 69-kV transmission loop reaches 102 MW, it will be at its maximum capacity to operate as a loop. This triggers the need to upgrade the voltage from 69-kV to 115-kV. This is part of the reason the City has been upgrading its existing substations to enable them to operate at either 69-kV or 115-kV. Once the Salzer Substation is completed, the only remaining substation that will need to be upgraded to accommodate 115-kV power delivery will be the Zimmerman Substation. The City will also need to upgrade the 26.25 mile 69-kV transmission line that runs between the Yelm Hydroelectric Project and the May Street Substation to accommodate the transition to 115-kV. BPA will also need to make changes to its system in order to upgrade from 69 to 115-kV. These include significant upgrades to the BPA-Centralia and BPA-Chehalis Substations. BPA will also need to upgrade a short section of the Centralia transmission loop to complete its capability to operate at 115-kV.

Planned Upgrade of the Zimmerman Substation

• Design in 2021 and Construct in 2022
• Location: Johnson Road - Centralia, WA
• The Zimmerman Substation is planned to be upgraded in 2022. This upgrade will increase the size of the power transformer from 20 MVA to 43 MVA. The new transformer will be built with a dual high-side voltage rating of 69 by 115-kV and a low-side voltage rating of 12.5-kV. This new transformer will be placed on the same type of earthquake-resistant foundation that was included in the Fords Prairie Substation upgrade and the construction of the new Salzer Substation. The entire substation will need to be rebuilt, with the exception of the switchgear building, to accommodate BPA's planned upgrade to 115-kV.

Planned Upgrade of the Yelm Transmission Line & Substation

• 2020 to 2024
• Location: The transmission line traverses from the Yelm Hydroelectric Project powerhouse substation to the May Street Substation.
• The City has been upgrading sections of the Yelm transmission line for the past ten years. Upgrading has included the replacement of existing poles with new poles that are equipped with insulators sized to accommodate the clearance requirements for 115-kV. As of March 2019, roughly 50% of the transmission poles have been replaced and upgraded. The substation located near the Yelm power house will also be upgraded from 69 to 115-kV, which will require a new substation transformer that is capable of outputting both 69 and 115-kV. This will keep the output from the Yelm Hydro Project compatible with BPA's upgrade of the transmission system around Centralia. The City plans to complete the upgrade of the line before BPA completes the upgrade to 115-kV.