Hell Hole Reservoir Dam Raise Project
Placer County Water

Placer County, CA

Completed in 1966, Hell Hole Dam and Reservoir sits about 10 miles west of Lake Tahoe in the Sierra Nevada Mountains. Standing at a massive height of 410 feet, it’s the 11th tallest dam in California. At an elevation of 4700 feet, and with 15 miles of shoreline, the reservoir is a frequent stop for many hikers and adventurers alike drawn by its pristine, clear water and astounding views of the snow-capped peaks of the Sierras. Operated by the largest water purveyor in Placer County, Placer County Water Agency serves over 41,000 customers.  The goal of the Hellhole Dam Raise Project was to increase the dam’s core elevation to 4,651 feet which will provide resolve for the dam’s settling since its construction as well as bring it 2.5 feet above the PMF flood level.  In one particular phase, the work consisted of temporarily storing approximately 8,000 cubic yards of rip rap excavated from the downstream slope of the dam as well as the construction of a temporary road which included the installation of three temporary ramps connecting to the top of the dam to the first bench on the reservoir side. When the project is complete the reservoir could increase by over 10,000 acre-feet of increased seasonal storage. MCK provided Project Controls, Contract Administration, Cost Estimating and Administration Services on the project.