When the owner of a mobile home park decided to bring solar energy to its residents, there were steep challenges to face. The Northern California community wanted to lower electric bills for its disadvantaged residents while generating clean energy. But mobile homes don’t have enough rooftop space to make the economics of solar work. The only feasible option: using a narrow but steep retention basin located next to the park that already served an important role diverting the area’s heavy rains.
So California electrical and general contractor Solar Gain, a mid-level C&I developer in Arizona and California, brought its long-term racking partner to the Camino Real Project. Terrasmart designed, engineered, and manufactured the 419-KW racking system, installed the driven-pile foundations in the retention basin, and secured the modules. Using its GLIDE Wave fixed-tilt racks, which are uniquely engineered to adapt to a terrain’s contours, Terrasmart was able to use continuous rows to reduce foundation material and labor. The team began the project in June 2023 and completed the structural installation in August, working its way through a few obstacles along the way.
Small project. Big challenges.
At 180 feet long and 200 feet wide, the narrow stormwater management pond presented thorny logistical issues. With a nine-foot basin depth and steep 15-degree slopes framing all sides, the site’s topography demanded unusually high elevation to keep the solar equipment safe above the retention pond.
The site offered little access space for materials and only a minimal ramp for the specialized equipment needed to secure the system. Materials delivery into the limited space had to be done off a busy street. And because the site was located right next to the mobile homes, work could only take place during standard business hours to avoid disturbing the community.
There were a few other challenges that tested Terrasmart’s exceptional problem-solving skills. First, the initial Geotech soil report detected extremely soft soils. While Terrasmart’s GRT pile driving machine can install up to a 24-foot pile, this project’s pile length needed to be 28-feet long, which was not doable. Therefore, Terrasmart advised the client to allow an on-site pull test conducted by our team, resulting in an overall workable post length of less than 21-feet. Lastly, let’s not leave out the fact that Terrasmart’s construction team was able to adapt to the extreme muddy conditions, laying construction matting onsite for all equipment to install safely and efficiently in six inches of water.
Nonetheless, Terrasmart’s team used its ingenuity and extensive experience to develop solutions to address the Camino Real site’s complexities. With nearly three decades of combined solar experience, Senior Construction Manager Mike Lewis, and National Account Manager Adam Brescia, led the way to successfully overcoming the challenges.
Ingenious engineering overcomes steep slopes
Ensuring safety while maneuvering heavy tracked equipment on steep slopes required inventive solutions that sprang from Terrasmart’s depth of experience installing more than 20 GWs of solar since 2010, Terrasmart’s full-service construction team did some minor grading and built a durable ramp that could handle heavy pile driving equipment. They also safely secured foundations on the basin’s 20% slope.
The basin’s flat zone offered limited maneuverability. To overcome this constraint, the team drove the posts and built each row independently as they worked their way up and out of the basin.
Digging deep for a foundation solution
While most racking companies can only handle driving piles up to 16-feet deep, Terrasmart’s seasoned drillers operated pile-driving machines to ensure accurate and plumb foundations using up to 24-foot posts.
To address the original geotech report’s suggestion for an unreasonably deep foundation, the team conducted an additional pull-test to confirm that a shallower foundation was feasible without the need for concrete piers. Terrasmart’s skillful value-engineering allowed the field team to shave several feet off the foundation design while foregoing concrete material costs altogether. Without this insight, the project would have been cost prohibitive.
Laying the groundwork to manage marshy conditions
The flood basin’s hard ground surface from the initial testing turned into a shallow marsh with six inches of water, bogging down the crew’s progress. While Solar Gain pumped out most of the water, Terrasmart installed construction matting to offer a stable base for the pile drivers, moving the matting sequentially to keep the machines operational within the tightly constrained space.
Elevated Results
Not only did Terrasmart successfully install the Camino Real system in extraordinary conditions, but it also completed the project under budget and ahead of schedule. Driving all posts instead of securing them on concrete piers saved the mobile home park owner nearly $20,000 thousand dollars in unnecessary material costs and shortened the project timeline by two weeks.
“The fact that we’re able to drive a 24-foot-long pile where most other people are limited to 16- feet gives us the opportunity to service projects that have unusually demanding requirements,” Brescia says. “Our unique skill set, and adaptability allow us to deliver elevated solutions, setting us apart for success on agrivoltaics or water management projects like Camino Real.”
“Terrasmart’s engineering and construction teams were forward-thinking in solving the project’s challenging site constraints. After thorough field testing and innovative design, collectively we were able to value engineer and execute the project flawlessly,” said President of Solar Gain, Roman Black. “Additionally, given the challenging condition of the site’s soft soils in greater than average rainfall in California, on top of working in a very confined space, Terrasmart delivered on time and within budget.”
Terrasmart is one of the few racking partners that can design and build elevated systems that raise modules above the average three feet of grade. With unique problem-solving capabilities and deep experience working on complex environments, Terrasmart can create a customized solution on any site working with any terrain, delivering success for any project.
