... Constructing solar farms in Hawaii is not easy — here's how Goodfellow Bros. gets it done | Solar Builder
 

Constructing solar farms in Hawaii is not easy — here’s how Goodfellow Bros. gets it done

Work for the Kawailoa Solar project included clearing and grubbing roughly 110 acres of land, moving 130,000 cubic yards of material, building four miles of rock driveways, digging one-and-a-half miles of swale, and building two substation pads.

More than a decade after the state mandate to reduce reliance on imported fossil fuel and the quest to produce 100 percent of electricity from renewable energy sources by the year 2045, the state of Hawaii is making solid progress. Hawaii’s Public Utilities Commission has mandated that Hawaiian Electric Companies purchase renewable power, which has resulted in a number of new wind and solar sites coming on line and proposed. Currently, utility-scale solar and wind make up about 30% of overall power supply, and a number of new renewable energy projects are in the works or planned on the major islands, including The Big Island, Oahu and Maui.

Many of these projects are developed by mainland corporations that must overcome region-specific issues to achieve success. Familiar challenges range from difficult soil conditions—geology varies from stiff clay and rock to extremely loose ash and coral (limestone) to stringent environmental controls and regulations in place to protect water. Perhaps the biggest challenge is the finite labor force. Since Hawaii does not have access to a transient or large labor force like the mainland U.S., finding workers and equipment is always a concern, particularly when construction demand is high.

Local expertise can help, and by working together, developers and contractors are making great strides toward meeting the state’s goals.

Waianae Win

One of the first large-scale solar facilities constructed in Hawaii was REC Solar’s Waianae Solar Farm on Oahu, developed by San Diego-based Eurus Energy America Corp. Completed in 2016, this facility, built on 198 acres of land, tripled the amount of utility-scale solar connected to Oahu’s grid at the time.

It also highlighted the challenges associated with construction in Hawaii. The land consists of coral, sand, alluvial soil, and thousands of surface and buried boulders. REC Solar looked to Goodfellow Bros. to make it happen.

The heavy civil contractor, a fourth-generation, family-owned business with a century of experience in the construction industry, brings island knowledge, talent and equipment to bear on every project. The company has an established and large labor force statewide to support its traditional heavy civil construction projects, which makes it very easy to level resources to support production expectations. With more than 700 pieces of equipment, it also has one of the largest heavy equipment fleets in the state of Hawaii, with machine control standard on most pieces.

Case-in-point, as the earthworks contractor for the Waianae Solar Farm, Goodfellow Bros. needed to prepare the land and install 12,716 driven piles.

Goodfellow Bros. won the 2017 Build Hawaii Award for Specialty Construction on the Waianae Solar project. Today the 127,160 solar panels generate 27.6 megawatts of electricity for Oahu homes.

The driven piles were installed using Vermeer PD10 pile drivers by Goodfellow Bros. When driven in soil and sand, installation was quick, but when driven in coral and areas with buried boulders, installation was tedious and, in around 20% of those situations, led to refusals where a minimum embedment of 6-ft could not be achieved. In order to remedy the problem, the Goodfellow Bros. team proposed, tested and implemented the use of Sandvik DP1500i top hammer drill rigs to pre-drill 6” diameter pilot holes through the coral and boulders to allow fast and efficient pile driving. Production went up and refusals fell to below 1%. Pre-drilling was provided by Blasting Technology Inc. (BTI), a subsidiary of Goodfellow Bros.

Crews also needed to install 6,820 drilled/set/concrete cast-in-place motor, combiner and center posts to support 127,160 solar panels. The motor, combiner and center posts required 12” diameter drilled holes at 5’-6” depths. The challenges of drilling thousands of holes through coral and various sizes of buried boulders were great, however the main issue with hundreds of the “center” posts were bracing them to meet strict tolerances at five degrees from plumb on sloping grades.

The project was completed per the client specifications. For its creativity and project delivery, Goodfellow Bros. won the General Contractors Association of Hawaii Build Hawaii, Award of Excellence in 2017 for Specialty Construction, more than $10 million.

Native Knowledge

Fast forward a few years to 2019. Clearway Energy Group brought three grid-scale solar power Oahu-based projects online: Kawailoa, Waipi‘o and Mililani, totaling 110 MW.

The Kawailoa Solar Farm, in particular, delivers 49 MW from over 500,000 solar panels. The site is located adjacent to the state’s largest wind farm, the Kawailoa Wind farm. The new solar farm fit perfectly into the existing footprint of the wind farm and already had the renewable electrical substation and grid in place.

With Moss as the general contractor, Goodfellow Bros. provided support for the construction of the project, which included grubbing roughly 110 acres of land, moving 130,000 cubic yards of material, building four miles of rock driveways, digging one-and-a-half miles of swale and building two substation pads.

One of the advantages of a civil contractor like Goodfellow Bros. is the substantial in-house surveying and value engineering capabilities. Goodfellow Bros. works closely with developers in a design assist role to optimize site grading, site investigation, budgetary proposals, etc. All of the company’s earthwork efforts are preconstructed in 3D GPS models by on-island modeling staff.

As well, earthwork teams use drone-mapping technology to perform aerial topography of the site and get up-to-date progress of work. In the case of Kawailoa, a repeatable flight plan for the drone was developed with a preset flight altitude and path. At the end of every workday, the drone conducted an aerial survey, to document and track the weekly production, allowing us to produce a better product for our client at reduced cost.

Cross Islands Delivery

Waipio Solar is a 60 MW solar farm covering 300 acres on the island of Oahu.

Solar farm development is expected to increase significantly in the coming years across all the major Hawaiian islands with an eye to meeting the 2045 deadline.

One of those projects currently in the works is the Big Island Region’s Waikoloa Solar Project. Despite the challenges of rock-laden terrain and recent nearby wildfires, the 300 acre development is on-track for completion in 2022. The 30 MW solar photovoltaic array, which includes a 120 MWh containerized lithium-ion battery storage system, will comprise one of the first utility-scale solar farms on this island.

Site preparation began in April of 2021 and Goodfellow Bros.’ initial portion of work is expected to be completed in early 2022, with additional work expected to extend the contract as designs are finalized.

To date, the contractor has graded over three miles of roads and the substation/switchyard pad, track-walked the site in preparation for pile installation, processed rock for aggregates, installed drain lines and drainage swales, and prepared the equipment pads for the power conversion stations (PCS).

From the very beginning, the Goodfellow Bros. project team has provided design assistance and value engineering. Among other things, the team helped the general contractor, BayWa r.e Power Solutions (fka Enable Energy), fine-tune the initial scope of work to make it more cost- and time-efficient. The team has also navigated the obstacles of uneven, ultra-rocky terrain. Additionally, the contractor paused its work several times to assist local fire crews battling wildfires in neighboring communities, providing on-site Cat D9 and D10 dozers to help with the firefighting efforts. In spite of the disruptions, the project remains on schedule.

Currently, there are a number of other solar farm projects under construction or proposed on Oahu, The Big Island, and Kauai—each with unique, and often challenging site conditions, as well as high workforce and equipment demands. Developers teamed with local talent such as Goodfellow Bros. are shining a bright, positive light on Hawaii’s quest to eliminate fossil fuels in the next 20 years.

Vicki Speed is a freelance writer covering the construction and green energy sector

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