The Challenge

The purpose of this project is to upgrade the seismic safety of Perris Dam to meet current new seismic standards. To accomplish this, Pulice is performing work to strengthen the dam’s foundation through the construction of a new compacted berm; extension of the existing blanket drain; construction of new drain line, new toe drain, and relief well system; and cement deep soil mixing treatment of the alluvium beneath the footprint of the compacted berm.

Pulice’s modifications include extending the existing drainage system that is comprised of 1.8 million CY of filter material, drain material, and compacted berm buttress. When complete, the berm will be 4,100’ long x 180’ wide x 50’ tall.


Upgrades to the 130-foot tall, earthen dam included strengthening roughly 800,000 cubic yards of foundation material by mixing cement with soil and reinforcing it with a 1.4 million-cubic-yard earthen stability berm placed on the downstream side of the dam. The dam upgrades were designed to withstand a major earthquake.

Perris Dam, constructed from 1970 to 1974, was identified as a high priority state-owned dam due to its proximity to nearby faults and large downstream communities.

Earthquakes pose some of the highest risks to dams in California. Since the late 1990s, DWR’s Division of Safety of Dams has conducted in-depth investigations and re-evaluations of dams located near seismic faults. Over the past 20 years, dam owners throughout California have spent approximately $1.5 billion on seismic improvements to dams.

The ERF project provides improvements downstream of the reservoir that would direct the flow of water in an emergency requiring the dewatering of the reservoir. Flows would be directed through a series of berms and lined and unlined channels that would ultimately terminate at the Riverside County Flood Control and Water Conservation District’s Perris Valley Channel. The Outlet Tower and ERF projects enhance the safety of the dam for other risks in addition to that posed by earthquakes.