Green buildings offer ‘golden’ savings opportunity for water and wastewater plants

Green buildings offer ‘golden’ savings opportunity for water and wastewater plants
The main process building at the new LaSalle, Ill., wastewater treatment plant features a "green" roof, where trays containing special plantings are located. The green roof provides additional insulation in the winter, heat dissipation in the summer, and reduced stormwater runoff. It was an important aspect of the LEED certification of the building. (Photos courtesy of Crawford, Murphy & Tilly)

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This summer we saw perhaps the most dramatic evidence yet of climate change. Reports as recent as mid-September indicate Arctic Sea ice has melted to an unprecedented size of 1.32 million square miles. That’s the lowest seasonal minimum extent measured via satellite since 1979, and reinforces the long-term impact of greenhouse gases.

Wastewater treatment and water plant operators are increasingly addressing the impact facilities have on the environment beyond water quality, and doing so when building or renovating plants. They are turning to the Green Building Council and its LEED certification program for guidance on making plants more environmentally friendly.

According to the council, buildings are one of the heaviest consumers of natural resources and account for a significant portion of the greenhouse gas emissions that affect climate change. In the U.S., buildings represent 73 percent of all electricity consumption and account for 38 percent of all CO2 emissions. They also use 13.6 percent of all potable water, or 15 trillion gallons per year.

What’s so ‘gold’ about being green?
Compared to the average commercial building, green buildings consume as much as 25 percent less energy and 11 percent less water, experience 19 percent lower maintenance costs, report 27 percent higher occupant satisfaction, and have the potential to lower greenhouse gas emissions up to 34 percent. Aside from doing what’s right for the environment, the potential for reducing operating costs should be a plus for any municipality.

This was the case with the new municipal wastewater treatment plant in LaSalle, Ill. Plant administrators made sure the new East Side plant, planned to serve an area poised for future residential and commercial growth, resulted in a technologically advanced and environmentally friendly facility. By implementing technologies such as a Vertical Loop Reactor from Siemens Water Technologies Corp., a membrane bioreactor system and a Cannibal biosolids destruction system (Siemens), the plant produces high-quality effluent necessary to discharge into the adjacent protected 303(d) listed Little Vermillion River and avoided a costly 1.5-mile outfall pipe to the Illinois River.

The LaSalle Public Works Department, led by plant superintendent and director of public works Sam McNeilly, worked closely with consultants, contractors and environmental groups to ‘bring home the gold’ in more ways than one, including working to achieve ‘gold’ level LEED certification.

Logic of LEED
LEED (Leadership in Energy and Environmental Design) is an internationally recognized environmental program deployed in more than 30 countries. It is a way to verify that a building or group of buildings are designed and built to improve energy savings, water efficiency, indoor environmental quality and CO2 emissions reduction. A third-party verification system – individuals certified with the Green Building Certification Institute (GBCI) – is used to determine if a project falls within LEED standards for different levels of certification: silver, gold and platinum.

“LEED is a viable approach to engineering, makes sense environmentally and should be looked at in a very hard way for retrofit or reconstruction,” says McNeilly. “Our LEED credits were earned mainly from the office and laboratory areas of our facility, but we were able to gain credits in a number of other ways.” Other earned credits ran the gamut from close monitoring of subcontractors’ purchases, use and disposal of construction materials, to green roofs on the new process building and offices.

One of the biggest challenges project managers for the LaSalle expansion faced, according to McNeilly, was getting contractors onboard with recordkeeping on everything from materials selected to construction waste. It required everyone to carefully think through what they may never have given a second thought to years ago.

“We found it very beneficial to hire a subconsultant who really understood LEED to manage the entire certification program,” McNeilly says. “He worked closely with our contractors to ensure the most environmentally appropriate materials were used, that as much as possible was purchased locally to reduce the environmental impact of shipping, and that construction waste was properly disposed.”

Certification begins with design
According to project manager Scott Knight, of Crawford, Murphy & Tilly design engineering firm for the LaSalle project, meeting requirements of LEED certification included rethinking many design elements and recommendations.

“When LaSalle asked us to help them get LEED certified, we had to look at a lot of things differently,” says Knight. “We enhanced the energy saving features of the administration building by adding more insulation than we typically would for both winter heating and summer cooling impact, and increased windows on the building’s south side for better light and energy efficiency.”

In addition to motion-sensing lights, zoned lighting was used so only in-use work zones in a large area or room could be lit. Sound attenuating tiles were added to the laboratory and administrative offices.

Sustainability was an important goal for the administration building and also in the plant itself, according to McNeilly. “When we planned our UV systems, we knew we needed long banks of lamps in open channels,” he says. “To reduce energy usage and minimize maintenance, we selected a newer system with only 32 lamps in a single inline housing tube that are also self-wiping for lower maintenance.”

But perhaps one of the most interesting aspects of the LaSalle project was the one that’s really green – the planted roof.

Green as grass
“A green roof was something we’d never done before,” says Knight. “When we started designing in 2009, there weren’t a lot of examples to look at out there, particularly at wastewater treatment facilities. But when we investigated the advantages over a regular membrane roof, the additional cost to add trays and plants was reasonable.”

The green roof, planted with low-growing plants, helps reduce stormwater runoff into the receiving steam and collection system, and aids in building insulation by helping deflect summer heat and retain heat in winter. Roof installation began with the standard rubber and water-sealed finish, then 18- by 12-inch-wide trays were fitted across the surface, filled with soil and planted with succulents and other heat-tolerant plant species. Hydrants located on the roof allow treated wastewater to water plants if necessary. The plants proved to be very robust, surviving one of the hottest and driest summers on record this year with only two or three waterings.

“There’s not a lot of maintenance required with this roof,” Knight says. “It’s proven to be a huge factor in minimizing stormwater runoff.”

Start LEED planning early
According to Knight, LEED required the new building be designed and built with energy efficiency and sustainability in mind, and also with thought to possible reuse of construction debris that might have incurred disposal fees in the past. There is a significant amount of documentation required during the construction process.

“If we learned anything from the LaSalle project, it is to think about LEED much earlier,” says Knight. “We brought our LEED professional on fairly late, when the design process was more than half complete. Our firm has since brought several LEED professionals on as part of our own staff to provide input from the initial planning stages all the way through construction.”

While it was possible to move to a green roof and to replace electric with solar motors to operate aerators (SolarBee), it was too late in the design process to implement other changes that would have been very attractive from a LEED perspective. Pervious pavement was one suggestion that couldn’t be done. Another was a geothermal system to capture wastewater heat to supply to occupied areas of the plant.

More ways than LEED to save
“If you’ve got a new construction project, or are going to be adding a new building at an existing plant, LEED offers what we call a ‘master site approach,’” says David Sheridan, Ph.D., environmental engineer and chair of the Water Efficiency Technical Advisor Group to the LEED Green Building Rating System Committees.

The Council’s 2010 LEED Application Guide for Multiple Buildings and On-Campus Building Projects (AGMBC) allows entities certifying more than one building to apply certain LEED credits campus-wide using a “LEED Campus Boundary” in addition to individual “Project LEED Boundary” demarcations. The benefit is that stormwater management, pollution reduction and parking allocation are considered from a whole-site perspective rather than allocating parts and pieces to individual buildings.

“LEED credits are usually awarded when energy requirements are reduced for lighting- and heating-enclosed, human-occupied spaces,” says Sheridan. “However, ENERGY STAR has guidelines that may be more practical for ways to reduce high-energy loads required for a plant’s industrial processes, such as running aerators and mixers.” He recommends treatment plant operators review energy-saving guidelines on the ENERGY STAR Buildings and Plants site, particularly the building Guidelines for Energy Management.

Adds McNeilly: “Thinking about energy efficiency is just a good thing to do even if you’re not trying to become certified.” 


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