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California Valley Solar Ranch

Santa Margarita, California

Low Water Crossings


NRG Solar


North Coast Engineering, Inc.


Papich Construction



Technical Description:

  • Product Detail:
  • ArmorFlex® open cell Class 50L 11,772-sf articulated concrete block (ACB)
  • 5,100-lf of 12-gage 8’ x 21.65” steel sheets of Contech Metric Sheeting

NRG Solar is a subsidiary of NRG Energy, a Fortune 500 company and pioneer in developing cleaner and smarter energy choices. In 2011, NRG Solar – now the largest solar power developer in the country – acquired California Valley Solar Ranch (CVSR), a 250- MW photovoltaic solar electric power plant designed and under construction by SunPower in San Luis Obispo County, California. The energy generated at CVSR will be sold under long-term power purchase agreements to help California achieve its renewable energy goals. CVSR includes SunPower solar arrays – groups of solar panels mounted on tracking technology – covering nearly 1,500 acres as well as an electric substation, operation and maintenance facilities and an approximate 2.8-mile, 230 kV generation tie-line.

The project also required numerous low water crossings for ephemeral streams. To comply with the County’s Conditional Use Permit conditions of approval, the structures had to meet strict requirements included in the California Regional Water Quality Control Board’s Waste Discharge Requirements (WDRs). The crossing needed to handle construction traffic, provide longevity for emergency services access and minimize the impact on the natural riparian areas.

“In order to match the natural shape of the existing ephemeral drainages and provide an improved surface that would remain stable and minimize the potential for erosion in large rainfall events, ArmorFlex ® was determined to be the best alternative,” stated Christy Gabler, Vice President of North Coast Engineering and Civil Engineer of the California Valley Solar Ranch. “Installation is kept to a minimal footprint, further decreasing potential impacts. Only minor grading is required to accommodate the new travel surface crossing the drainage.”

After reviewing various options, 11,772-sf of ArmorFlex Class 50L was chosen as the best solution for the eight low-water crossings. ArmorFlex met the rigorous requirements of the WDRs by providing a minimally-invasive installation with minimal landform alteration of low-to-no grading. This, in turn, minimizes the impact on biology, ecology, stormwater quality and air quality. The sensitive habitat of endangered species could not be altered or harmed.

In addition to meeting the strict WDR guidelines, ArmorFlex provided cost benefits and an ease and speed of installation. For instance, one low-water crossing utilized five 8’ x 21.33’ mats that were installed in just three hours with the use of an excavator.

“It was a slam dunk to install the ArmorFlex mats,” stated Jeff McGuire, Project Manager of Papich Construction. “I thought it would be more difficult, but once I saw one mat go in, that’s all I needed to see. I knew the rest would be set easily.”

Along with the ArmorFlex mats, 5,100-LF of 12-gage, 8’ x 21.65” steel sheets of Contech Metric Sheeting were utilized as cut-off walls in locations where the soils were conducive. An Aluminized Steel Type 2 coating provided improved durability versus galvanizing and resistance to corrosion resulting in a longer potential product life. The method of installation for Metric Sheeting also adhered to the strict environmental requirements of the project.

CVSR’s solar panels utilize the SunPower® Oasis™ Power Plant technology which tracks the sun’s movement during the day, increasing energy capture by up to 25 percent over conventional fixed-tilt systems. The electricity generated by CVSR is enough to serve a yearly average of 100,000 homes. The project also provided an economic boost by creating approximately 350 construction jobs and injecting $315 million to the local economy.  

Technical Description:

  • Product Detail:
  • ArmorFlex® open cell Class 50L 11,772-sf articulated concrete block (ACB)
  • 5,100-lf of 12-gage 8’ x 21.65” steel sheets of Contech Metric Sheeting

800-338-1122 |


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