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Cold Spring Granite’s Rip-Rap Used in Crane Valley Dam’s Seismic Retrofit Project

The Crane Valley Dam, in Madera County, Calif., has been functioning for more than 100 years. It is located on the North Fork of Willow Creek, a tributary of the San Joaquin River. The dam features a 145-foot-high, hydraulic and rock-fill embankment, with a thin, central concrete core wall. It is 1,880-feet long; the crest of the dam is at an elevation of 3,380-feet. However, when the dam was built between 1902 and 1911, very little was known about seismic activity.

To improve the dam’s ability to safely withstand seismic events and to meet state and federal safety guidelines, Pacific Gas & Electric (PG&E) commenced a seismic retrofit project. The earthen dam modification project added approximately 253,000-cubic-yards of rock fill to areas on the upstream and downstream faces of the dam. To provide more freeboard, the crest was raised and re-graded to an elevation of 3,387-feet, about 7-feet above the original minimum crest elevation.

A Century in Stone

To help with the project, the contractor, Parsons Commercial Technology Group of Pasadena, Calif.,

turned to a business that has also existed for more than 100 years – Cold Spring Granite.

Several years ago, Cold Spring Granite began a quest to understand how its business impacted the environment and the communities it serves. Natural stone is an environmentally preferable material compared to many other products such as concrete or composites due to its durability, minimal processing needs and local availability in many markets. Cold Spring Granite’s goal is to become the greenest stone manufacturer in the world.

In particular, the Quarry Materials Division utilizes quarried materials that are not suitable for dimensional stone applications to create jetty, rip-rap and aggregate. This extracted stone is perfect for use on construction job sites by excavating companies, contractors, landscapers, and trucking companies. Applications for the extracted stone include all construction aggregate uses including concrete stone, bituminous mixtures, road bases, rail sub ballast and ballast, erosion control, shore protection and dam reconstruction.

More Granite Needed

As part of the project, Parsons opened a quarry about one mile from the project site. “We developed the on-site quarry as a source of rock for the dam retrofit,” said John Magyar, Construction Director for Parsons, “but we were also looking for a source of rock off-site to supplement the on-site rock in the event we ran into shortages.”

Cold Spring Granite submitted product samples to Parsons to show that the granite would meet the required density, durability and size specifications. While the color of the stone was not important for this project, the functionality was critical. From a technical standpoint, the stone had to meet ASTM testing standards for durability and density. The rip-rap had to be durable enough to sustain years of environmental conditions such as rain and snow, and it had to be dense enough to withstand erosion from the constant thrashing of waves against the dam.

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CRANE VALLEY DAM MADERA COUNTY, CA

The contractor investigated several quarries in the area and chose Cold Spring Granite because of its proximity to the dam site (about 35 miles away) and its ability to provide the granite in the specified density, durability and size requirements.

For the Crane Valley Dam project, Cold Spring Granite supplied 128,000-tons (the equivalent of 6,400-truckloads) of Sierra White granite, in sizes from 3/8-inch to 20-inches, for use as structural reinforcement. “The onsite quarry we had established did not produce what our expectations were to meet the needs of the project,” Magyar said. “We relied rather heavily on Cold Spring Granite’s quarry to be able to finish the job by the scheduled completion date.”

Cold Spring Granite then hired Kroeker, Inc., a demolition contractor in California’s Central San Joaquin Valley, to partner in turning its dimensional granite into usable product for the dam. Kroeker came to Cold Spring Granite’s Sierra White Quarry, located in Raymond, Calif., to extract the granite blocks. The blocks were then moved to Kroeker’s worksite where hydraulic breakers reduced the blocks into more manageable sizes. This material was then transferred to a rock grizzly for final sizing, and stockpiled for loading and delivery to the dam site.

“Our safety director spent a lot of time with Cold Spring Granite’s personnel and the truck drivers, to ensure the safety of local residents and visitors.”

- John Magyar Parsons

COLD SPRING GRANITE

Stone Name: Sierra White™

Quantity: 128,000 tons

Kroeker, Inc.Central San Joaquin Valley, California

Parsons Commercial Technology GroupPasadena, California

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Project Materials:

Contractors:

Pacific Gas & Electric (PG&E)San Francisco, CA

Project Owner:

Cold Spring GraniteCold Spring, Minnesota

Material Supplier:

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17482 Granite West Road Cold Spring, MN 56320-4578T 800.328.5040 F 320.685.8490www.coldspringgranite.com

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Road and Trucking Challenges

One of the challenges of the Crane Valley Dam project involved the large number of trucks needed to transport the rip-rap – 6,400-truckloads. Because the roads in this part of California are extremely narrow, safety was of prime importance – not only for the truck drivers but also for the residents of the area.

“In order to keep up with the placement schedule on the site, we were running approximately 12-to-20 trucks making 3-to-5 round trips per day,” noted Magyar. “There was road construction on the route that continually held up the truck deliveries, and the roads were narrow and winding.”

Willow Creek is a tourist area and it does not have highway-grade roads coming into the resort area where the dam is located. Most of the trucking was done in the summer months when the area was full of tourists.

“Our safety director spent a lot of time with Cold Spring Granite’s personnel, and the truck drivers, to ensure the safety of local residents and visitors,” Magyar commented. “The safety of the truck drivers was also a concern, especially on the narrow roads.”

According to Rodney Ainsworth, General Manager of Kroeker, the trucking restrictions and road grades were definitely the “tricky part” of this project. “The county had restrictions on which routes we could use, what days we could run, and how many tons per day we could haul,” Kroeker said. “The road into the dam site was very narrow and winding, and when the area opened for recreation the use of the road had to be shared.”

A Team Effort

Throughout the project, the team of Parsons, Cold Spring Granite and Kroeker worked together to insure the project schedules were met. “Every project has its issues, but we were always able to sit down, resolve problems and keep the project moving,” said Magyar. “Cold Spring Granite met all of its commitments to keep the retrofit on schedule.”

“The Cold Spring Granite team worked diligently to maintain a satisfied customer and a strong working relationship with our team.”

- Rodney Ainsworth Kroeker

Ainsworth concurs: “The Cold Spring Granite team worked diligently to maintain a satisfied customer and a strong working relationship with our team. They helped us maintain both the production and delivery schedule by supporting us and providing help when problems occurred. Their knowledge of the surrounding area and proximity of the quarry made the job more productive.”

The proximity of Cold Spring Granite’s quarry to the dam site helped to offset the increased transportation costs. Cold Spring’s ability to provide the granite in a timely fashion made the quarry valuable to the project. With the retrofit project completed, the Crane Valley Dam is now able to handle the expected seismic activity that might occur in Madera County.