Ground-Mount Solar

ECA Solar Geotechnical Services for Ground-Mount Solar

gzadan — Fri, 05 Nov 2021 19:36:11 +0000

ECA Solar Geotechnical Services for Ground-Mount Solar gzadan Fri, 11/05/2021 - 15:36

Challenge

Preferred foundation systems for ground-mount solar projects are short driven or screw piles able to resist high lateral loads. The piles are typically designed by a design-build contractor based on geotechnical studies and multiple site-specific load tests. For bidding projects, designers need to know the soil type and potential for shallow obstructions, such as boulders and bedrock. ECA Solar and GZA needed a cost-effective approach gain site access and to characterize the site for pile foundations by addressing these design priorities.

Solution

GZA’s preferred approach to field subsurface investigation for ground-mount solar projects uses test pits that allow boulder counts, and observation of ease of excavation, soil types and layering. Many more test pits can be performed in a single day, compared to borings. Test pits also allow for collection of bulk samples for laboratory thermal resistivity and corrosivity testing.

Benefit

GZA completed its subsurface exploration program solely using test pits. Along with GZA’s geotechnical report, subsequent loads tests at the site helped the design-build pile contractor design a cost-efficient pile system for the project. GZA was a trusted partner on ECA Solar’s team that brought this project through to completion in 2021.

26 acres of ground-mount solar constructed in 2021
GZA’s geotechnical report, completed in December 2019, included 2 days of test pit explorations
Test pit excavations (versus borings) allow full observation of soil types, layering and potential for obstructions, such as boulders and/or bedrock
No tree cutting was allowed for GZA’s exploration program
A mini-excavator was required to facilitate access through mature trees

Energy

Geotechnical Engineering Services

Borrego Solar Systems, Inc. Geotechnical Services for Ground-Mount Solar

Anonymous — Thu, 26 Sep 2019 14:01:02 +0000

Borrego Solar Systems, Inc. Geotechnical Services for Ground-Mount Solar Anonymous Thu, 09/26/2019 - 10:01

Challenge

Preferred foundation systems for ground-mount solar projects are short driven or screw piles able to resist high lateral loads. The piles are typically designed by a design-build contractor based on multiple site-specific load tests. For bidding projects, designers need to know the soil type and potential for shallow obstructions, such as boulders and bedrock. Borrego and GZA needed to develop a cost-effective approach to characterize sites for pile foundations by addressing these design priorities.

Solution

GZA’s approach to field subsurface investigation for ground-mount solar projects uses test pits that allow boulder counts, and observation of ease of excavation, soil types and layering. Many test pits can be performed in a single day, compared to borings. Test pits also allow for collection of bulk samples for laboratory thermal resistivity and corrosivity testing. As GZA’s relationship developed with Borrego, we added report details related to equipment pads and site access roads.

Benefit

Over the course of numerous projects on many different site types, from open farmland to forested parcels, GZA has become a trusted partner on Borrego’s team. GZA efficiently delivers a report product that meets Borrego’s unique needs.

Bruce Fairless, P.E.

Principal, Geotechnical Solar Practice Lead

Insights

Over 95 ground-mount solar geotechnical studies since 2013
Unlike borings, test pit excavations allow full observation of soil types, layering and potential for obstructions, such as boulders and/or bedrock
Array areas vary from about 5 acres to nearly 100 acres; typical size is approximately 15 to 35 acres

New York

Energy

Geotechnical Engineering Services

Borrego Solar Phase I Northern Long-Eared Bat Habitat Assessments

Anonymous — Tue, 24 Sep 2019 13:40:31 +0000

Borrego Solar Phase I Northern Long-Eared Bat Habitat Assessments Anonymous Tue, 09/24/2019 - 09:40

Challenge

Many of Borrego’s planned solar developments require Phase I habitat assessments for the federally-listed Northern Long-Eared Bat (NLEB) and Indiana Bat because the potential projects involve tree clearing within the US Fish & Wildlife Service’s NLEB buffer zone. GZA’s Ecological Services group was retained to conduct numerous Phase I assessments and provide reports required for permitting.

Solution

To date, GZA has conducted over 50 NLEB and Indiana Bat assessments and reports under Section 7 of the Federal Endangered Species Act (ESA) which stipulates that these due diligence assessments and surveys require the determination of the presence of any known hibernacula or maternity roost trees on or near the properties involved. The sites, ranging from 30 to more than 150 acres, have varied from completely forested areas to re-use of existing gravel pits, farm fields and cranberry bogs. The habitat assessments included walking all areas of the proposed cutting as well as the immediately adjacent areas. A natural community map of all habitats found was then created based upon field observations. Each natural community unit was assessed for its potential to support NLEB summer roosting and foraging activities. Within each natural community unit, dominant and common vegetation assemblages were identified by stratum. Within the tree stratum, average diameter at breast height (dbh), canopy cover, and species composition were assessed. Particular attention was paid to standing dead trees, high snag density, clutter density, or other trees that might provide roosting locations. Standing dead trees were assessed relative to their size, size relative to other trees, location, distribution and degree of decay. Notes on structural diversity and complexity of each natural community unit as well as other habitat features associated with NLEB (corridors, water sources, clutter) were made to better inform the bat habitat assessments.

Benefit

GZA’s natural resources experts, well-versed in the latest regulatory requirements and keenly familiar with the geographic region, conducted the surveys and assessments required to successfully move the solar development projects forward.

Insights

Phase I NLEB Habitat Assessments in Compliance with US Fish & Wildlife Regulations
Over 50 Sites
Due Diligence Section 7 Assessment Reports to Client for Each Site

Connecticut

Energy

EHS Regulatory Compliance

Natural Resources and Ecological Services