Curry Village Install Underground Electrical and Propane System (YH 2020)

Yosemite National Park » Curry Village Install Underground Electrical and Propane System (YH 2020) » Document List

JUSTIFICATION:

This project is for the design development and review of the new underground electrical service for Curry Village.

During the 2018/2019 winter storm season the electrical systems in Curry Village sustained excessive damage. Upon evaluation of that damage it was determined that the entire existing electrical system is out of code creating a safety hazard for guests and employees.

With this determination all electrical must now convert from overhead power to underground power. This is a time sensitive project as the existing system is hazardous.


SCOPE:
Construction schedules and phasing will be determined at a later date.

An electrical engineer will create plans for a new underground electrical service in all of Curry Village. Proposed construction to install electric lines in Curry Village is anticipated to occur in phases in the following areas:
- Phase 1: Curry Village South (400-700 Tent Area)
- Phase 2: Curry Village North (Boystown Area)
- Phase 3: Huff House Area
- Phase 4: Cooks "without bath cabins" (WOBs) area and Curry Village Pavilion
- Phase 5: Tent cabins behind Registration Building

The project anticipates that there will be approximately 3.5 miles of trenching, with trench widths of 24 inches and depths to 36 inches below ground surface for conduit that will contain the electrical wire. The trenches will include a 2 inches thick layer of sand bedding at the bottom to support the conduit, with 12 inches of sand backfill placed on top. The final 0-12 inches below surface will consist of soils initially excavated from the trench. Due to the addition of sand in each trench, this project will generate a large quantity of soils that will not be backfilled. These spoils are anticipated to be staged at the abandoned Upper River Campground approximately 0.25-mile to the north.

As part of the electric line installation, various precast concrete electrical pull boxes will be installed throughout the project area. These will be up to 48 inches wide and 30 inches deep. Installation will involve excavating up to 4 inches around the box and 12 inches below it to remove existing soils and replace them with compacted pea gravel. Electrical grounding rods will also be used, measuring ¾-inch diameter and 10 feet long, meaning they extend to a maximum depth of 10 feet below ground. Multiple electrical main service panels will also be installed, with trenching for associated posts measuring approximately 24 inches deep and 6 inches in diameter. Concrete reinforced pads for mounting equipment will also be installed throughout the project area. These will require excavation to accommodate a 6-inch-thick slab that will extend up to 1.5 inches above the surrounding grade.
The undertaking will also include removal of some abandoned existing electrical equipment. All exposed and above grade conduits, wiring, pull boxes, outlet boxes, panels, transformers, and electrical equipment will be removed. Abandoned conduits that are below grade will be left in place. All conduit risers will be cut and removed to 12 inches below the ground surface. At the completion of excavation, all surfaces, roadways, sod, walks, and curbs will be restored to their original condition.