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.