The impact that these and other sustainable practices can have on a project is considerable, says Patrick Choudoir, project development manager for AZCO, a Burns & McDonnell company that provides industrial prefabrication and construction solutions.
“By finding ways to modularize a design and fabricating components in a controlled shop environment, you not only produce less waste, you also achieve more sustainable designs, more consistent quality and greater schedule certainty,” Choudoir says.
When these prefabricated components arrive at the construction site, the differences are evident, Choudoir says: “EPC projects that use off-site fabrication tend to have smaller, less congested job sites. Given the smaller scope of on-site construction activities, field laborers face fewer safety risks as well.”
Outages are also shorter, which is why the design-for-manufacturing-and-assembly approach was embraced early by energy and oil and gas companies that can’t afford lengthy downtime.
“When it comes down to it, sustainable EPC is just more efficient,” says Sara Tomashitis, a project manager and one of the hundreds of Burns & McDonnell employee-owners to earn credentials as an Envision Sustainability Professional (ENV SP) from the Institute for Sustainable Infrastructure. “Not only does it help keep a project on schedule and on budget, but the sustainable aspect also provides a positive environmental benefit.”
The Envision framework offers third-party verification of civil infrastructure projects that meet certain criteria for sustainability and resiliency. While not every project may seek Envision certification, the program’s structure and tools can be helpful guides to owners interested in improving their sustainability profile.
“Every owner has different wants, needs and expectations,” Choudoir says. “Some are content with solutions that use sustainable materials and minimize impacts on the natural environment. However, a growing number are seeking solutions that directly align with their organizations’ corporate responsibility, decarbonization and sustainability commitments.”
Here’s a deeper dive into sustainable EPC:
The Design Process
“On a typical stick-built project, contractors are selected when design reaches the 30% to 60% mark,” Choudoir says. “That changes when a project includes prefabricated components. Because of the upfront work that it requires, it makes more sense to engage fabricators and other trade partners early so they can have greater input on design.”
Working together, these parties dissect the end product, looking for opportunities to modularize or simplify its components. Drawing on this collaboration, designers complete 90% to 100% of the design before moving to the next phase of the process.
“The design-for-manufacturing-and-assembly requires that more time be spent upfront on engineering,” Choudoir says. “But with a vertically integrated team that works together to identify potential obstructions, these projects also tend to have less scope creep and fewer change orders.”
For sustainable procurement programs, procurement professionals consider two factors when assessing the sustainability of materials and equipment.
First, the professionals assess the net embodied carbon in materials by using third-party-verified Environmental Product Declarations (EPDs) where available. EPDs make it possible to calculate and compare the carbon footprint associated with the manufacturing and transportation of each option under consideration. A product’s direct environmental impact is also considered.
“On solar farm installations, for example, designers may specify a dry-type transformer for the solar inverters that convert solar energy into electricity,” Tomashitis says. “They are more environmentally friendly than traditional transformers, which contain mineral oil that could seep into the soil and groundwater.”
In addition to assessing product sustainability, procurement professionals also evaluate each vendor’s corporate sustainability programs and practices. In some cases, bids are conditioned on vendors’ acceptance of the owner’s sustainability terms and conditions.
The Construction Process
When projects include prefabricated components, the role of on-site contractors also changes to include less construction and more installation services. But a smaller construction footprint is just one of the ways that an on-site team can support sustainability.
EPC teams can also limit the environmental impact of construction activity in other ways. For example, when clearing trees from a construction site, they can employ sustainable harvesting practices that make it possible to maintain or increase tree population numbers over time. Harvested trees can then be sent to mills for lumber or paper production, or they can be transformed into mulch for residents in nearby communities.
On large sites that require earthwork and stormwater management, special attention can be paid to revegetation efforts. Depending on the owner’s preferences and goals, seed mixes may be designed to eliminate invasive plant species, attract pollinators or minimize mowing needs.
Strong community engagement, marked by regular and transparent communication with key community stakeholders, takes on great importance — and is a key theme woven throughout the Envision certification process. That includes reaching out into the community to support workforce sustainability.
“A solar program we’re working on involves about 1.5 million solar panels, a small portion of which are damaged and can’t be used,” Choudoir says. “Many of these have been donated to a local union training facility where laborers are using them for training purposes.”
In another case, classes from a local technical college with a solar maintenance program have visited a solar construction site, with the goal of helping to develop a local workforce capable of maintaining the solar farm for the long term.
“The good news is that we are still only scratching the surface of what is possible through sustainable EPC,” Tomashitis says. “With almost every project, we discover something new. The opportunities are endless.”
Glycol Recycling at Denver International Airport
The expansion of a closed underground pipe and storage pond system will make it possible for Denver International Airport to recycle and reuse more of the glycol utilized in airplane deicing. Stormwater mixed with glycol from the airport is currently captured in the underground pipe network and conveyed to lined storage ponds, where the fluid mixture is measured and stored.
“When the glycol-to-water concentration has been sampled to be in compliance with discharge permits, typically lower than 1%, the water is allowed to be discharged to the sanitary sewer system for conveyance to a wastewater treatment plant,” says Nick Tessitore, project manager at Burns & McDonnell. “Stormwater with a higher concentration of glycol is conveyed to an on-site treatment facility for recycling. It is currently estimated that approximately 60% of the glycol sprayed at the airport is captured and recycled on-site.”
There is an ongoing project to expand the system, increasing the amount of water it can collect and glycol that can be recycled. “The ultimate goal is to collect and recycle enough glycol on-site that outside supply is not needed,” Tessitore says.
A More Environmentally Friendly Substation Foundation
Every new solar or wind farm that comes online requires two new substations — one to support the farm itself and the other to connect it to the power grid. When choosing substation foundations — the most time- and resource-intensive component of a substation project — utilities have traditionally favored bored concrete piers.
But with the volume and pace of new construction picking up, Burns & McDonnell and AZCO have started considering less labor-intensive methods and more sustainable ways to lay a deep foundation. The answer: helical piles.
These prefabricated deep foundations are made of steel piles that have helical plates welded along their shafts. A three-person crew can install as many as 20 to 25 helical piles a day, twisting each one into the soil, similar to how a corkscrew is twisted into a bottle of wine. These foundations are immediately ready to bear the weight of the substation foundation.
Compare that to concrete piers, which require a crew of five to 10 people to excavate the soil and pour concrete into the freshly drilled shafts, which then require an additional 28 days of cure time.
Faster and less disruptive to install, with a far smaller environmental impact, helical pile foundations are currently being installed on a number of Burns & McDonnell substation projects.