The Oroville Dam is the tallest dam in the U.S. Located in Northern California along the Feather River in Butte County, it has been at the center of the United States’ heated debate over the deterioration of critical infrastructure from coast-to-coast.

During widespread rainfall during the 2017 California floods, damage to the dam’s main spillway appeared, resulting in its closure. As operator, the California Department of Water Resources, assessed the extent of damage and mitigation measures. Precipitation continued, and the lake level rose until it flowed over the emergency spillway, necessitating reopening the damaged main spillway. As water flowed over the emergency spillway, headward erosion threatened to undermine and collapse the concrete weir, which could have sent a 30-foot (10

Rockfall Protection – Creating a Safe Work Environment

During Phase One, Maccaferri supplied 60,000 sqft of SteelGrid™ HR400 to meet safety standards on the site. The Maccaferri SteelGrid™ HR400 is a patented high strength composite steel wire mesh which combines hexagonal double-twist steel wire mesh with high strength steel cables interlaced in the longitudinal direction during the manufacturing process. With exceptionally high tensile and punch strength at

m) high wall of water into the Feather River below and flooded communities downstream. Although a collapse never occurred, the main spillway suffered significant damage, and the bare slope of the emergency spillway was significantly eroded.

These failures forced a mandatory evacuation of over 200,000 Californians located in the low-lying areas along the Feather River Basin. In addition to its effects on the local community, the local fish hatchery also suffered. Debris carried downstream caused damage to the Feather River Fish Hatchery due to high turbidity. State workers evacuated over nine million fish and eggs downstream to a satellite hatchery adjacent to Thermalito Afterbay to mitigate the damage.

Kiewit, the project’s general contractor was hired in April 2017

very low deformation, SteelGrid™ HR400 is specifically designed to provide surficial stability for rockfall drapery applications. Contractors and stakeholders were pleased with the product and decided more should be installed during Phase Two to continue the culture of high safety standards on-site.

Work during Phase Two will include the complete demolition and reconstruction of the upper portion of the existing spillway. Flanking each side of the upper spillway, near the dam opening,

OROVILLE DAM SPILLWAY RECONSTRUCTIONOroville, CA

SPOTLIGHT PROJECT

to lead the repair work through Jan. 1, 2019. The company is rebuilding the main spillway, placing a 65-foot underground secant wall to stop erosion on the emergency spillway and laying concrete at least 10 feet thick between the cutoff wall and the concrete weir that holds water in the lake. When the work is done, about one-third of the 3,000-foot hillside will be lined in concrete, twice as much as originally planned. Kiewit completed work on Phase One of the project in November which focused on the lower portion of the spillway.

Project OwnerCalifornia Department of Water Resources

General ContractorKiewit

InstallerNeil’s Controlled Blasting

Project ScheduleApril 9 - 28, 2018

Project OverviewOne of the most important infrastructure projects in the United States needs critical rockfall protection before construction can safely continue.

ProvenIndependently tested & certified in accordance with the strictest industry standards

QualityUse the highest quality raw materials & provide world-class engineering with custom design and manufacturing capabilities

Quick and Cost EffectiveDeveloped in conjunction with contractors to provide quick and easy installation

PerformanceDesigned for the most challenging rockfall conditions

StrengthSteelGrid and RockMesh provide exceptionally tensile and punch strength at very low deformations.

DurabilityGalMac and polymer coated providing two-to-five times the service life of our competitors

WHY MACCAFERRI ROCKS!

high rockfaces posed a threat to anyone working in the area. Before spillway construction could be continued, critical measures had to be taken to protect personnel and equipment from falling rock.

The very narrow area between the cliff face and service spillway walls required mesh drapery to protect operations happening in the area. As the permeable backfill was removed, an additional 30-feet of drapery was added as a ‘skirt’ or extension to the existing 120-foot drapery section. The superior longitudinal and transversal tensile strength of the RockMesh® 3030 as well as the functionality of splicing panels, (lacing additional material to the bottom of the RockMesh® drapery system) made the Maccaferri product the natural choice for the contractor.

The very aggressive schedule required nearly 120,000 sq.ft. of RockMesh® 3030 and 60,000 sq.ft. of SteelGrid™ HR400 to be delivered and installed before May 1st. The purchase order was signed initiating the project April 3rd, and all three truckloads of mesh delivered on time to give Neil’s Controlled Blasting sufficient time to install.

This installation will not only protect workers and equipment during day-to-day operations but is strong enough to sustain any rock disturbance as a result of blasting that will take place to demolish the spillway in that area.

Maccaferri RockMesh® steel cables are integrally woven into our double twist mesh during manufacturing, forming a single, easy to deploy the product

Hand scaling was perfromed before the installation of Maccaferri Rockfall system

Installation of the drapery was simple, accomplished on schedule, and nailed to the surface of the slope for additional protection

Maccaferri, Inc9210 Corporate Blvd, Suite 220Rockville, Maryland, 20850T: + (1) 301.223.6910 E: info@us.maccaferri.com

www.maccaferri.com/us

Maccaferri’s SteelGrid® is critical to keeping workers safe on the Oroville Dam project