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Construction Update

AES has requested approval from the California Energy Commission (CEC) to conduct limited construction work outside of normal construction hours (extended work hours) at the Alamitos Energy Center (AEC).

The previously approved extended hours work to install modules and components for the Heat Recovery Steam Generator (HRSG) has been completed. The extended hours construction activities were undertaken to minimize the inherent risks associated with the temporary condition of the incomplete HRSG structure (structural instability, heavy haul logistics, etc.).

AES is submitting this new request to conduct limited extended work hours through January 1, 2019. The additional scope proposed includes:

Structural steel erection

This work includes the erection of structural steel, followed by piping, instrumentation and electrical operations. This work is usually conducted in parallel to progress each task simultaneously, instead of sequentially, to avoid delays to the critical path construction schedule. However, due to the constraints of the project site and surrounding operations, it is difficult to conduct these tasks at the same time on the same shift while providing enough equipment, lay down space and work area for each task.

Cable pulling

Cable pulling operations are a key component to finalizing the power distribution system. To ensure the project is ready to accept the back-feed power next spring, AES must have the construction of the power distribution system complete by December of this year. This will ensure the project is ready to turn the system over to the startup and commissioning team for testing and checkout prior to energization. In addition to mitigating schedule risk, the request to pull cable at night is due to the need to place cable tuggers and reels in major access ways on site which prevents both site access and other construction activity in the same area. Executing this work during the day would significantly disrupt the movement of materials and equipment throughout the site, and would disrupt other critical path operations.

Critical pipe welding

Extended work hours are also requested to facilitate critical pipe welding code requirements for pre-heat and post-weld heat treatment on chrome and high pressure carbon steel piping. Prior to the start of welding the pipe must be pre-heated to several hundred degrees. Once heated to the correct temperature, the pipe must be kept at that temperature until welding is complete. After welding is complete, the pipe weld must go through a post-weld heat treatment to ensure the final product is malleable and not hard and brittle. Per the California Building Code, once post weld heat treatment has started it cannot be stopped. The extended working hours would allow critical welds to be completed in a single, uninterrupted operation.

Based upon the needs outlined above, we propose a second shift of workers that will extend until 3:30 AM Monday through Friday evenings and until Midnight on Saturdays.

We understand the importance of minimizing impacts to the community and surrounding neighborhoods. Our contractor, Kiewit, has proposed the following mitigation measures:
  • All workers on the afterhours shift will park on-site within designated daytime parking areas.
  • The expected sound level at the nearest sensitive receptor from construction activity outside of normal construction hours is 45-50 dB.
  • Noisy activity associated with the work will be limited to normal construction hours and all activities will be performed in a manner to reduce excessive noise.
  • Back up alarms on mobile equipment used during the work will be taped off during extended work hours past 7:00pm.
  • Task lighting will be used in a way that minimizes any light trespass, backscatter to the night sky, or any illumination beyond the project site.

These mitigation strategies have proven to be effective as there have been no complaints received to date due to previous and existing extended hours work. By continuous implementation of mitigation measures, impacts to the surrounding community will be greatly reduced. To monitor noise and light impacts, AES will assign personnel to periodically monitor the nearby communities to identify and mitigate potential impacts from light or noise.

Thank you for your patience as we work as quickly and safely as possible to complete this important project. Please feel free to contact our project hotline at (888) 363-2226 or email at with any questions.