Off-Grid Communication Site Design

Project Summary

Westchester Services LLC was asked to assist a large Stored Energy provider to design an off-grid communication site for a regional wireless carrier in the Sierra Nevada Mountains just south of Yosemite National Park in Central California.

This project presented a unique set of challenges to which our team provided a variety of creative solutions. The design included the improvement of a 2-mile long access driveway through the rugged mountains. The site design was delayed by wildfires in the area and did not allow access to the site for over 60 days while the fires in the area were being extinguished. Additionally, the site was built on a decomposed granite rock outcropping with only 3”-6” of topsoil, meaning traditional grounding measures or even horizonal chemical rods would not be effective. After consulting with several groundings specialists, we opted for a horizontal plate ground system buried in a bentonite fill to achieve the best ground we could obtain.

The soil/rock conditions, as well as the large, nearly vertical solar panel array and seismic conditions in California, presented the need for a unique rock anchor system. Decomposed granite meant a traditional expansion anchor would only crumble the rock, so special care needed to be utilized to epoxy the anchors deeper into the rock. The same was necessary for the fence post bases as auguring a hole and cementing in the fence posts was not an option.

With the site more than 2.5 miles from the nearest commercial power, an off grid solar solution with a propane generator back-up option was chosen to power the site. Because the site’s elevation above the valley below, the site design only required a 25’ tall tower. The site location and elevation has between 7 to 10’ of snowpack each season, so the customer wanted an elevated platform to ensure the equipment was accessible and somewhat bear-proof. Special signs on the site indicate that any technicians visiting the site should close the gate behind them to make sure a bear does not enter the site and cause mischief.  This was an exciting site to be a part of and the Westchester Services team is proud to be able to provide our services.

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