Challenge

From permitting to construction completion, this solar development program – design and construction of a solar field atop three previously capped landfills – presented challenges: as the first project of its type in the state, the permitting process was without precedent; protection of the landfill caps was paramount; and as-built vs. design discrepancies were encountered during construction at one site.


Solution

Drawing upon a successful permitting track record in neighboring states, GZA developed and presented a permitting process to the owners, EPA, and RIDEM, who readily adopted the process for this project. GZA’s geotechnical study included a bear capacity analysis and design of the ballast block foundations to maximize the number of solar arrays installed at each landfill while maintaining minimal ground pressure, to protect the landfill cap; this resulted in different-sized ballast blocks specialized for each location. To further protect the cap, GZA used low ground pressure equipment to manage construction activities, advised the contractor on weather/ground condition-related scheduling, and provided input on the design of all the wiring and supporting trays for the above-ground installation. During construction, GZA conducted a crane feasibility analysis for the installation of the transformer, and, when design issues at one site resulted from inaccuracies in the as-built drawings provided, GZA completed necessary stormwater analysis and restoration design to address unexpected erosion after the solar array installation.


Benefit

This project tapped a broad range of GZA’s technical capabilities and benefited from GZA’s stellar reputation with federal, state, and local regulatory agencies, helping move this first-of-its-kind Rhode Island project through the regulatory and construction process on time and under budget, while protecting the integrity of the landfill caps at all times.