Click on the link to jump to the article listed
Traffic on the road to net-zero energy is increasing, thanks to greater interest, better solutions
If you want to understand where energy management in the wastewater sector is headed, there is no better place to start than Saco, Maine.
Here in this scenic city of 19,000, the 16,000-m3/d (4.2-mgd) wastewater treatment plant (WWTP) has cut its heating-oil consumption by 88% in recent years. Its electric bill is down 30%.
The city’s nine-person wastewater treatment staff has cut energy costs by doing some things you might expect: installing variable-frequency drives, programmable thermostat temperature controls, and other energy-efficiency upgrades at its facilities. But it also has done things most wastewater utilities many times its size have not yet considered — such as running effluent through a heat pump and using it to provide geothermal heating and cooling to the WWTP’s maintenance and processing buildings. Saco’s wastewater department also is using solar power to heat its maintenance garage and sky tubes to magnify the natural lighting available. It’s even producing 16 kW of energy — worth about $70 a month — using a small wind turbine.
What’s being demonstrated in Saco — as in thousands of communities across the nation — is really a shift in thinking, according to Howard Carter, deputy director for wastewater treatment. “Since around 2005, we’ve been working to demonstrate to the community that we’re not the polluters,” said Carter. “We’re the exact opposite.”
A long-term strategy
It’s more than community relations that is driving Carter and other forward-thinking wastewater operators to rethink their approaches to energy management. The fact is, energy is expensive; it can account for 30% to 40% of a wastewater utility’s budget and up to 60% of a municipality’s total energy expenditures. Plus, ever tighter water quality requirements are placing added pressure on budgets that are stretched thin already, according to Jason Turgeon, environmental protection specialist at U.S. Environmental Protection Agency (EPA) Region 1.
“There is this thinking that if you want cleaner effluent, you must use more energy,” Turgeon said. “But that doesn’t necessarily have to be the case. The ways operators choose to run their plants can have a huge impact on their energy use.”
Still, it can take years for even the most motivated plant operators to install the upgrades needed to balance higher treatment costs. That is why EPA supports a continuous improvement approach to energy management planning, Turgeon said,pushing older plants to set a goal of 20% energy reduction.
For cities like Saco, the long-term goal is even more ambitious: net-zero energy — that is, refashioning its WWTP so it produces as much energy as it consumes while leaving no carbon footprint behind. While still a distant dream for most WWTPs, net zero — or some close approximation of it — is now within reach for operators with the will and the resources to fund it (see sidebar, p. 20).
There are many roads to net zero, noted James Wheeler, team leader in EPA’s Office of Wastewater Management. All involve a combination of reducing energy demand and increasing onsite renewable power generation. Most utilities concentrate on the energy-efficiency side of the equation first, and with good reason. “The less energy you use, the less you need to produce,” said Wheeler.
Smarter aeration systems.
The lowest-hanging fruit in most WWTPs remains the aeration systems used to remove organic materials and nutrients. The blowers needed to operate these systems typically consume about half of a treatment plant’s electricity, Wheeler said. “Treatment plants tend to overaerate,” he said.
Chicago’s Metropolitan Water Reclamation District used to be one of them, said
Thomas Kunetz, the district’s assistant director of engineering. “In previous generations, energy was cheap, and people’s primary focus was on effluent quality,” he said. “But today, every little bit [of energy savings] counts. If we can turn down our blowers for a time because there is a lower oxygen demand, we will.”
A consultant hired by the district to help identify ways it could curtail energy use for short periods, in fact, demonstrated that it could shut down a blower for an hour with no effect on treatment.
By installing advanced controls on high-speed blowers, using different parameters to control the flows — even changing the time of day the equipment is operated, plants also can achieve significant cost savings, said Matthew Yonkin, senior manager at Siemens Water Industry Inc. (Warrendale, Pa.). “Depending on the type of system you start with, the electricity used by the blower can be reduced by as much as 70%,” Yonkin said. “We know of plants that made upgrades and were later contacted by their utilities to see what was wrong. The reduction in load was that dramatic.”
Advanced primary treatment.
“When you treat wastewater at its source, there is less need for tertiary treatment, which reduces your energy demands further down the process,” Turgeon said. Newer technologies are not only getting out more of the pollution in wastewater on a first pass, they also have a smaller footprint and low energy demand, Carter said.
The City of Saco, for example, installed a newer treatment system at an overflow site near its downtown area. Combining screening, sedimentation, and disinfection in a single compact unit, the system delivers significantly higher performance than a standard clarifier in a fraction of the space, Carter said. Another compact primary treatment system on the market uses a finely woven, rotating wire cloth to filter out up to 50% of suspended solids at the source.
Increasing renewable energy production
While one set of engineers is focused on minimizing the amount of graywater that enters a WWTP, another set is recognizing there may be “gold in them there pipes.”
Wastewater contains 10 times the energy needed to treat it, according to the Water Environment Research Foundation (Alexandria, Va.). Recapturing this energy remains capital-intensive, however, which has led to an industrywide push to bring down those costs.
Codigestion gets real
. In October 2011, EPA reported that 3171, or 43%, of U.S. WWTPs treating 3785 m3/d (1 mgd) or more now use anaerobic digestion to produce methane from their wastewater biosolids. This percentage might improve soon, thanks to the increased attention being placed on using codigestion to increase digester efficiency and boost energy production, according to Peter Cavagnaro, water solutions program manager at Johnson Controls Inc. (Milwaukee).
With codigestion, operators are adding a high-strength waste, such as food scraps, to the biosolids in a digester. Food waste produces three times the methane as wastewater biosolids, said Laura Moreno, an environmental scientist for EPA Region 9. It is also more digestible than wastewater solids, reducing processing time. Still, codigestion is not always economically feasible.
“A food processor or wastewater utility alone often can’t afford to invest in a digester,” Yonkin said. “In Europe, we’re beginning to see larger, centralized codigestion facilities that process multiple wastestreams and generate enough power to make the investment both feasible and worthwhile.”
Improvements also are being made to improve the efficiency of the digesters themselves, Cavagnaro said. “There is considerable research being done on new digestion technologies and improvements to the mixing systems,” he said.
Tapping wastewater’s geothermal potential
. These days, it isn’t necessary to treat wastewater to draw energy from it. Two athletic villages at the 2010 Winter Olympics in Vancouver, British Columbia, were heated by capturing the thermal energy in slow-moving wastewater as it traveled through long distances of pipe. “They just put a heat pump on it,” Turgeon said. “Think of all the sewer mains that could potentially be tapped into to heat and cool nearby buildings if we started looking at underground pipe this way.”
. The idea of putting the flow of water to work is being played out another way in San Diego. There, a hydroelectric facility is producing 1.35 MW of power generated by the 30-m (100-ft) descent of treated effluent exiting the city’s Point Loma WWTP into the ocean. This is just one example of a host of alternative energy sources — from wind and solar power to fuel cells and waste incineration — that are in various stages of development and use around the U.S.
Barriers to entry remain
Energy management is good for the environment. It reduces the demand on the electric grid and transforms waste into valuable resources. So, why isn’t everyone doing it?
Money remains perhaps the biggest barrier. Rebates, incentives, and financing programs that use energy cost savings to pay for the upgrades all help. But they don’t reach everyone.
Regions where energy prices are lower also find payback more challenging, Kunetz said. “Every treatment plant is unique, with its own climate, its own economics, and its own circumstances,” he said. “It’s more feasible for some to reach net-zero energy in the next 10 years than others.”
There are the limits to the technologies themselves. “It takes a certain amount of sunny days for solar [technology] to be cost-effective,” Wheeler said. Wind, too, has drawbacks, with greater application in California, the Northeast, and the Plains states than elsewhere.
Plant operators that are making the transition find that the sophisticated new systems they’re installing also are creating new challenges. “Before, a plant operator didn’t need a college degree,” Turgeon said. “It now takes fewer people, but they must be highly skilled with automation and comfortable with using data to optimize and manage their systems.”
The lack of a strong track record of success also remains a significant barrier for many WWTPs. The problem is, net-zero energy doesn’t happen overnight.
Take the Strass WTTP, a 38,000-m3/d (10-mgd) plant that serves 31 communities in the valleys east of Innsbruck, Austria. Originally commissioned in 1999, the plant since has been optimized for energy efficiency. Solar, wind, and hydroelectric energy all are produced onsite.
“It took them 10 years to get there,” noted Wheeler, “but they’re now generating 108% of their power requirements.”
As more plants like this one go on-line and tell their stories, Wheeler predicts, others will follow.
“The word is starting to get around,” Wheeler said.
— Mary Bufe,
How low can treatment plants go?
As nutrient limits tighten throughout the United States, treatment plants seek to improve performance while lowering costs
Practically all signs point to more-stringent nutrient limits for wastewater treatment plants (WWTPs) throughout the United States. As more states seek to address water quality problems associated with nutrients, treatment plants increasingly must find ways to reduce nutrient concentrations in their discharges as cost-effectively as possible. Although the search for increasingly efficient treatment approaches almost certainly will produce innovations, some question whether the costs of achieving ultralow nutrient limits may outweigh the benefits.
Because they are set in response to local conditions, nutrient regulations can vary greatly among states and regions. To date, some of the most stringent nutrient limits in the United States tend to occur along the East Coast, said Marie Burbano, an associate at CDM (Cambridge, Mass.). “Very low phosphorus limits are becoming common for freshwater discharges in New England, and increasingly stringent nitrogen requirements are being negotiated for many plants discharging to key saltwater bodies, such as Narragansett Bay and Long Island Sound,” Burbano said. Requirements for enhanced nutrient removal for both phosphorus and nitrogen are in place in the Chesapeake Bay region, and very low limits are being implemented in Florida.
Historically, nitrogen has been the nutrient of concern in estuaries, while phosphorus is more likely to be an issue in freshwater rivers or lakes, said Christine deBarbadillo, wastewater practice and technology leader at Black & Veatch (Overland Park, Kan.). As a result, many of the WWTPs operating biological nitrogen removal and other advanced processes for reducing nitrogen concentrations are located within watersheds that directly affect estuaries. However, as numeric nutrient criteria are developed for receiving waters in each state, and as concerns grow about the effects of nutrients on the health of the Gulf of Mexico, more WWTPs across the country likely will have to implement biological nitrogen removal in the future, deBarbadillo said. “It’s coming,” she noted.
Meeting the limits
To reduce nitrogen concentrations, WWTPs most commonly use some variation of the two-step biological process known as nitrification and denitrification, in which ammonia–nitrogen is converted to nitrite and nitrate and then released into the atmosphere as nitrogen gas. Meanwhile, the activated sludge process also may be configured to achieve phosphorus removal. In conventional applications, these biological nutrient removal processes can be designed to reduce concentrations of total nitrogen to approximately 3 mg/L and total phosphorus (TP) to as little as 0.1 mg/L, when followed by filtration, deBarbadillo said.
Meanwhile, adding metal salts to precipitate phosphorus is another standard approach for lowering TP concentrations. However, to reduce TP levels below 1 mg/L, “filtration really becomes mandatory,” said Casey Whittier, product manager for biological process offerings in the water technologies business unit of Siemens Industry Inc. (Warrendale, Pa.).
Faced with what may be some of the lowest nutrient limits in the nation, Spokane County, Wash., opted to use chemically enhanced primary treatment and membrane bioreactor technology at its soon-to-be-unveiled 30,280-m3/d (8-mgd) Regional Water Reclamation Facility (WRF). CH2M Hill (Englewood, Colo.) designed, built, and will operate WRF for 20 years. At press time, the facility was expected to begin operations by early 2012, said David Moss, water reclamation manager for Spokane County Utilities.
Because its receiving stream, the Spokane River, is subject to a total maximum daily load for dissolved oxygen, WRF faces strict seasonal limits for nutrients. Between March 1 and Oct. 31, the facility essentially must achieve TP concentrations of less than 0.050 mg/L. Meanwhile, the facility also must comply with strict limits on total ammonia, including a limit of essentially 0.250 mg/L between June 1 and Sept. 30. “I know of no other facilities that must meet limits this low,” Moss said.
Innovations on the way
In terms of innovative approaches for biological nutrient removal, James Barnard, Black & Veatch’s global practice and technology leader for advanced biological treatment, said that he expects to see increased use of the process known as granular activated sludge. Whereas traditional activated sludge systems generate fluffy conglomerations of organisms, under certain conditions, the bacteria can be made to form granules that cluster together more readily. In doing so, bacteria on the outside of the cluster conduct nitrification, bacteria on the inside effect denitrification, and phosphorus-accumulating organisms within the clusters remove phosphorus. Because the clusters of granules settle more quickly than the more common fluffy floc, downstream clarifiers can be smaller.
“I believe we’re going to see more [granular activated sludge systems] in the future,” Barnard said, “because the footprint is so much smaller, and the cost is so much less.”
Used in Europe for some time, sidestream processes for treating high-strength ammonia streams generated by solids digestion and dewatering operations are beginning to catch on in the United States. The filtrate left over after dewatering may contain as much as 30% of a plant’s nutrient load, deBarbadillo said. Because this stream typically is returned to a WWTP’s influent, it “has a significant impact” on nutrient levels in the wastewater, she noted.
For this reason, a handful of U.S. facilities have made plans to implement sidestream treatment processes for nitrogen. One biological option is nitritation followed by denitrification of filtrate. A second process, known as “deammonification,” consists of partial nitritation followed by an anaerobic ammonium oxidation (“anammox”) process using a novel group of bacteria. Both processes convert ammonia to nitrite and then to nitrogen gas more directly than conventional nitrification and denitrification while requiring lower levels of aeration and less or no organic carbon. As a result, both approaches reduce nitrogen levels in dewatering filtrate more cost-effectively than conventional approaches to nitrification and denitrification, offering the potential for “considerable savings” in terms of energy and chemical use, deBarbadillo said.
For its part, Hampton Roads Sanitation District (HRSD; Virginia Beach, Va.) is in the process of installing an anammox system as a sidestream treatment process at its York River WWTP, said Charles Bott, HRSD’s research and development manager. To be used for treating centrate, the installation is expected to be one of the first in North America.
Meanwhile, HRSD also is investigating the possibility of using the anammox approach as part of the main secondary treatment process, rather than simply as a means for removing nutrients from centrate. As part of a long-term pilot project, HRSD and several partners are attempting to implement the anammox process at the district’s Chesapeake Elizabeth WWTP in place of conventional nitrification and denitrification. Although the lower temperatures and ammonia concentrations present in the normal secondary treatment process pose obstacles that must be overcome if the project is to succeed, Bott said, a successful outcome could help reduce the cost of nitrogen removal significantly.
Emphasizing nutrient recovery
Nutrient recovery from wastewater typically focuses on phosphorus because, unlike nitrogen, supplies of high-quality phosphorus are thought to be decreasing. With demand for phosphorus expected to rise in light of a growing world population, the price of phosphorus is only expected to increase in the long run, Barnard said. As the price increases, the “payback period [for phosphorus-recovery projects] will get less and less,” he said. This realization is spurring interest in efforts to recover struvite, in particular, from municipal wastewater, Barnard said.
HRSD implemented struvite recovery at its Nansemond (Va.) WWTP approximately 1.5 years ago, Bott said, and the process has worked well and proven economically justifiable. “It is a revenue generator,” he said.
Urine separation is another concept that HRSD aims to investigate as part of the construction of a new administration building. “If you can separate urine, you’ve separated most of the nitrogen and phosphorus in a very concentrated stream,” Bott said. To test the idea, HRSD will install nine waterless urinals and one urine-separating toilet in the restrooms of the new building, which is scheduled to be completed in about a year. Urine will be collected in a small storage tank designed to control pH levels and odor, and then hauled to HRSD’s Nansemond facility to be combined with centrate for struvite recovery.
Despite its appeal, cash-strapped agencies may not have the luxury of pursuing nutrient recovery, said Thomas Kunetz, assistant director of engineering at the Metropolitan Water Reclamation District of Greater Chicago. For this reason, a “paradigm shift” is needed in which financial and regulatory incentives are provided to encourage agencies to pursue nutrient recovery and “move to a more sustainable approach,” he said.
Thinking for the long term, Barnard has begun advocating the storage of ash generated by the incineration of biosolids from plants that conduct biological removal of phosphorus. Because the phosphorus remains in the ash, storing it in a dedicated disposal area essentially amounts to creating a phosphorus “mine” that can be accessed easily in the future, he said.
Factors to consider
For treatment plants facing the prospect of lower nutrient limits, compliance costs are a chief concern, especially for facilities already operating near the limits of technology. “I don’t know how much lower than that [WWTPs] can go,” without increasing costs exponentially, Burbano said.
Along similar lines, a key question to be addressed, Whittier said, is “at what point is it more beneficial to have modest nutrient limits at many plants, as opposed to ultralow limits at a few plants?” Lowering nutrient levels in effluent requires using more energy, results in greater greenhouse gas emissions, and may provide diminishing returns in terms of benefits to the environment, he noted.
For WWTPs faced with low nutrient limits, a key consideration involves whether such limits are short- or long-term in nature, said J.B. Neethling, technical director for wastewater at HDR (Omaha, Neb.). Unlike toxic substances, which have short-term effects on the environment, “nutrients have a slow-acting impact,” Neethling said. Therefore, many in the wastewater community contend that nutrient limits should be longer-term in nature — preferably annual, rather than daily or weekly. However, regulators sometimes adopt an approach similar to that used for toxics, setting daily or other short-term limits for nutrients. Because of variations in influent nutrient loads, daily nutrient limits may prove “problematic” for some WWTPs, Neethling said.
Another issue in need of further study, Neethling said, is the extent to which “slowly degradable” nutrients in effluent are bioavailable in the environment. If some of a WWTP’s nutrient load is not available to plants and thus not contributing to algal growth, how should that fraction be regulated? The answer to this “long-term question,” Neethling said, could significantly affect the cost of future nutrient removal efforts.
Ultimately, reducing the deleterious environmental effects resulting from excessive nutrient levels will require more efforts to address nonpoint source pollution, rather than simply setting stricter limits for WWTPs, said Samuel Jeyanayagam, vice president and senior principal technologist in the Global Water Technology Group at CH2M Hill. “With an overall watershed approach, rather than looking at treatment plants alone, we may be able to achieve more environmental benefit,” he said.
— Jay Landers,
Navigating a rough terrain
With rumors of impending bond defaults, an ongoing bad economy, and reductions of federal funding, water and wastewater utilities face another rocky financial year
In November, Jefferson County, Ala., filed for Chapter 9 bankruptcy protection, which, according to some media reports, was the largest government bankruptcy filing in U.S. history to date.
County leaders gave several reasons for the filing, including a credit rating downgrade in 2008 and the end of an occupational tax in 2011 that had accounted for 40% of the county’s annual unrestricted revenues, according to a Nov. 9 Jefferson County press release. But the county’s “sewer system crisis” also was blamed. Several creditors were owed a total of more than $1 billion for wastewater system upgrades. According to the press release, the sewer system’s court-appointed receiver demanded that the county pay $75 million from the county’s general fund to help cover these debts, which county leaders argued would have impaired the county’s ability to provide essential services to residents.
“Faced with the risk of a significant depletion of the general fund reserves and the sewer creditors’ refusal to agree to any reasonable settlement offers made by the commission, the commissioners were left with no responsible choice but to file Chapter 9,” said Jefferson County Commissioner Jimmie Stephens, chairman of the finance committee, in the news release.
The bankruptcy filing would not only affect Jefferson County “but also the entire state,” argued Alabama Gov. Robert Bentley in a Nov. 9 news release.
“My administration has worked closely with the Jefferson County Commission, the sewer creditors, and legislators to work toward a settlement that is in the best interests of the Jefferson County residents and rate payers,” Bentley said in the release. “The settlement the county rejected today would have reduced the sewer debt by more than $1 billion and significantly reduced proposed sewer rate increases. By filing for bankruptcy, the county commission now relinquishes control of its affairs into the hands of a federal bankruptcy judge.”
Though the governor blamed the bankruptcy filing solely on county leaders’ inability to negotiate with creditors, the county’s financial woes probably had something to do with the water and wastewater industry’s ongoing debate about full-cost pricing, said Blair Troutman, president of BlueWater Consulting (Knoxville, Tenn.). BlueWater provides financial management and engineering services to public and private utilities.
“Here you have a county that would rather go into default than raise rates,” Troutman said.
Jefferson County isn’t alone in its unwillingness to charge residents unprecedented rates for their water and wastewater in order to cover the true costs of these services, Troutman said. “At the current backdrop, most [utilities] are just surviving,” he said.
But the financial landscape — which once offered several reliable means of financing outside of rate increases — is getting rockier, leaving many utilities with fewer options.
“Bond funding is now an issue,” Troutman said. “With the market the way it is, a lot of the utilities have been rerated or have even seen a downgrade in their ratings, which means borrowing has now become more expensive. Some utilities can’t get market funding at all, and the [State Revolving Fund] is drying up. It’s putting more strain on the utilities.”
A shaky bond market
Though the size of Jefferson County’s bankruptcy is unprecedented, some stock market watchers had predicted something like this would happen. As early as September 2010, Meredith Whitney — a well-respected stock analyst who famously predicted in 2007 the downfall of big banks — released a 600-page report in which she and other analysts detailed the poor financial conditions of many states and suggested that several municipalities could begin defaulting on bonds guaranteed by the cities and towns — something that had been rare in previous years.
The municipal bond market started to witness a serious shake-up soon after, with investors withdrawing $20 billion from municipal bond funds in a matter of weeks, according to a Jan. 26, 2011, Wall Street Journal article. But many in the financial industry said that though municipalities now had an increased chance of default, water and wastewater utilities were still safe bets for investors.
“The municipal water, sewer, and drainage utility sector should continue to see rating stability this year despite the impact of state budget pressures on the numerous communities it serves,” according to a Jan. 26, 2011, report issued by Standard and Poor’s (New York). “One of the key positive rating factors is that user charges account for nearly all operating revenues of most utilities rated by Standard and Poor’s Ratings Services. In contrast, we have observed that general governments and other local and regional entities, such as school districts, often have to rely on state aid for substantial portions of total operating revenues.”
Doug Scott, managing director at Fitch Ratings (New York/London), concurred. He said in 2011 that water and wastewater utilities benefit from being seen as an essential service. “There is always a demand for them, compared to banks and insurance companies that don’t have the same level of demand,” he said.
Although municipal bonds from water and wastewater utilities are viewed as some of the most reliable investments in the market, several of these utilities still experienced problems during their bond offerings.
A little more than a year ago, the Gwinnett County (Ga.) Department of Water Resources tried to refinance $160 million of debt, said Peter Frank, deputy director of business services at the utility. Initial estimates in September 2010 had shown that the department could reduce its interest rate by 2.5%.
“That would have been more than enough savings we needed to move forward,” Frank said. But 2 months later, when the department tried to issue bonds, market conditions were not as favorable, and the bond interest rates were much too high for the utility to move forward with refinancing, Frank said. The utility rejected all bids.
“At that point in time, a lot of the California bonds were going to the market,” Frank said. Also, he said, rumors of big defaults in the municipal bond market had begun.
Because of the market upheaval, some utilities decided to avoid bond offerings entirely.
Andrew Kricun, deputy executive director and chief engineer at Camden County (N.J.) Municipal Utilities Authority, said in 2011 that his utility uses the New Jersey State Revolving Fund (SRF) for a lot of its financing. “We believe that is a significantly better opportunity than the municipal bond market,” he said.
Kricun said the New Jersey SRF has been an “extremely stable option because of the much larger pool of applicants. Moreover, they offer 20-year loans at 25% to 50% of the market rate. The low interest rate has been a very key factor in our being able to completely upgrade our wastewater treatment plant without having to raise rates.”
Kricun said many utilities pass on the SRF program because “they think it is more onerous, but our experience has been that the requirements are not significantly different, and the annual debt service savings far outweigh any minor inconveniences.”
More reductions in federal funding
Even if the SRF offers a good alternative to the bond market, the fund is not what it used to be. In the early days of the Clean Water Act, many utilities borrowed from the SRF liberally with great financing terms, Troutman said.
“Most utilities in 1972 built [their infrastructure] on 20 cents on the dollar because of federal and matched state funds,” Troutman said. “But we’re not going to see 1972 levels of funding again.”
Nothing emphasized this better than the rancorous debt-ceiling debate last year. After several months of arguing and negotiation, the U.S. Congress finally agreed to raise the ceiling by $1 trillion in 2011 and another $1 trillion in 2012, reduce discretionary spending by $1 trillion during the next decade, and create a bipartisan “supercommittee” of congressional members charged with finding another $1.5 trillion in cuts by the end of 2011. But the supercommittee announced in December that it could not reach an agreement on the remaining cuts. This triggered across-the-board budget cuts that will be enacted in 2013. The water and wastewater industry is bracing itself, though in 2011 many were lobbying congressional leaders and the Obama administration not to go forward with extensive cuts, particularly to the Clean Water and Drinking Water SRFs.
The American Water Works Association (AWWA; Denver), Water Environment Federation (WEF; Alexandria, Va.), Association of Metropolitan Water Agencies (AMWA; Washington, D.C.), and National Rural Water Association (Duncan, Okla.) sent a joint letter in August 2011 to U.S. Senate Majority Leader Harry Reid (D–Nev.) and U.S. House Speaker John Boehner (R–Ohio), urging them to fund the Drinking Water SRF at $956 million and the Clean Water SRF at $1.5 billion for fiscal year (FY) 2012, maintaining FY 2011 levels.
Pat Sinicropi, legislative affairs director at the National Association of Clean Water Agencies (Washington, D.C.), said in September that her association was “putting together a package to go to the supercommittee and the Obama administration, urging them to not decrease funding, but increase it. These projects increase jobs and definitely have an impact on the economy.”
To offer another financing route, some are promoting the creation of a Water Infrastructure Finance and Innovation Authority (WIFIA).
“It’s only for water, but it’s similar to the infrastructure bank [which offers financing for transportation projects],” said Tommy Holmes, legislative director at AWWA.
The infrastructure bank was created by the Transportation Infrastructure Finance and Innovation Act. “What we’ve proposed under WIFIA is more cost-efficient [than current funding mechanisms],” Holmes said. “It leverages federal dollars instead of being reliant each year on appropriations.”
According to a fact sheet compiled by AWWA, WEF, and AMWA, WIFIA would be a mechanism that “could lower the cost of capital for water utilities while having little or no long-term effect on the federal budget.” WIFIA would access funds from the U.S. Department of the Treasury at long-term Treasury rates. These funds would be used to provide loans or other credit support for water projects. Funds would flow from the Treasury, through WIFIA, to larger water projects or to the states that wished to borrow money for their SRFs to enlarge their pool of capital. Loan repayments with interest would flow back to WIFIA and then into the Treasury with interest, the fact sheet explains.
“With this model, you only have to cover the defaults, and water utilities have a default rate of about 0.04%,” Holmes said.
Troutman said this isn’t the first time that the WIFIA idea has been put forward.
“These ideas came out years ago,” Troutman said. “[The industry] told Congress that it needed the bank,” but the problem was that the industry did not show a united front, he said.
The top 10% to 15% of utilities objected to the idea of a water industry infrastructure bank, because they said it wasn’t fair that they had been taking care of their assets for years through other funding mechanisms and now other utilities would be able to get cheap funding, Troutman said. But maybe this time around, with the bad economy and reduction in federal funding, the industry will have more agreement on the issue, he said.
“If it just means cheap funding again like during the Clean Water Act, I don’t think it’s a good idea though,” Troutman said. “That free lunch just hurt the industry in the long run” by establishing unrealistic expectations, he said.
In October, U.S. Sen. Amy Klobuchar (D–Minn.) sponsored S. 1769, the “Rebuild America Jobs Act,” which includes the establishment of an American Infrastructure Authority that would “provide direct loans and loan guarantees to facilitate infrastructure projects that are both economically viable and of regional or national significance.”
At press time, the bill was still in committee and had not been sent to the Senate floor for a vote.
Preventing overflows right from the start
A growing number of cities are cutting costs and meeting regulatory standards by installing green infrastructure
Until recently, the dominant paradigm for tackling combined sewer overflows (CSOs) has relied on so-called gray infrastructure. Cities typically have curbed CSOs by increasing the capacity of their systems with billion-dollar investments in storage tanks and pipes, said Jeff Moeller, a senior program director at the Water Environment Research Foundation (Alexandria, Va.).
This approach improves performance but doesn’t address the underlying problem of too much stormwater generated upstream of the sewer system, Moeller said.
Some cities are taking another approach. By using “green” stormwater controls, such as rain gardens, cities can downsize their gray infrastructure, extend its lifetime, save money, create green jobs, and enhance livability.
The list of these cities is growing. New York City announced a draft agreement in October with the state Department of Environmental Conservation to invest $187 million in green infrastructure by 2015 to prevent CSOs. Portland, Ore., is using green infrastructure to cut 35% of the city’s overflows at just one-tenth the cost of its $1.4 billion CSO abatement program. And on Oct. 31, an independent commission examining the proposed $5.7 billion wastewater storage tunnel beneath London concluded that CSOs could be prevented with a shorter tunnel paired with green infrastructure solutions. The commission noted that the mix of green and gray infrastructure would not only meet water quality objectives but would do so at less cost and disruption to Londoners.
Nature is the best designer
Green infrastructure relies on plants and soils to soak up water, said Robert Pitt, an environmental engineer at the University of Alabama (Tuscaloosa). At its heart, green infrastructure is a demand management technique that eliminates a portion of the stormwater entering the system, thereby raising the capacity of the system by lowering the pressure on it. Techniques include rain gardens, porous pavement, green roofs, and cisterns.
Rain gardens are the stars of green infrastructure, Pitt said. They store runoff, cutting peak flows, and also reduce overall runoff volume by evaporating water through plant transpiration and promoting infiltration through the soil and sand layers beneath the plants. “Pilot projects in Kansas City, Mo., show that residential rain gardens can absorb 100% of the runoff from homeowners’ roofs,” Pitt said. In fact, rain gardens are so cost-effective compared to gray infrastructure that Seattle has a program to reimburse homeowners up to $4000 for adding rain gardens to their properties, said Andrew Lee, a CSO manager at Seattle Public Utilities.
Seattle has been cracking down on CSOs since the 1960s and therefore has relied until recently on separating storm and sanitary sewer lines and ramping up stormwater storage devices, Lee said. However, “the city now leads with green strategies and estimates that 10% to 15% of its remaining CSOs could be eliminated with the use of green infrastructure,” he said. If the city had relied on green infrastructure from the beginning, green technologies could have removed up to 50% of CSOs, he noted.
Lee cautions that green infrastructure won’t work in areas where soils don’t drain, slopes are too steep, or where there just isn’t enough space. However, in some Seattle neighborhoods where street runoff was directed into roadside rain gardens, runoff volumes were cut by 99%, he said.
In the 1970s, Portland, Ore., discharged 38 billion L/yr (10 billion gal/yr) of CSOs into the Willamette and Columbia rivers, said Bill Owen, senior engineer at the Portland Bureau of Environmental Services. By the end of 2011, the city will have reduced that flow to 1.1 billion L/yr (300 million gal/yr), meeting the requirements of its Long-Term Control Plan. Roughly 35% of the CSO reduction will come through the use of green infrastructure.
One of Portland’s biggest successes is the disconnection of downspouts at more than 26,000 properties, Owen explained. Directing flows into rain gardens or grassy swales, downspout disconnection keeps more than 4.5 billion L/yr (1.2 billion gal/yr) out of the system, cutting CSOs by 20%. The $13 million program has helped the city avoid having to invest more than $300 million in gray infrastructure, such as tanks and tunnels, to curb CSOs, he said.
“There is no one green infrastructure solution that will work for every entity — it all depends on local conditions,” said Scott Struck, a senior water manager in the Golden, Colo., office of Tetra Tech (Pasadena, Calif.). Helping cities optimize the combination of green and gray infrastructure solutions to CSOs is a growing research area, he said. Choosing the best strategy requires a comprehensive decision-support system that includes geographic information system analysis, computer modeling of the performance of alternative scenarios, and cost–benefit analyses that look at external benefits of green infrastructure, such as reducing urban heat-island effects and improving quality of life.
U.S. EPA gives green infrastructure a boost
The move toward green infrastructure could be getting a lift from the U.S. Environmental Protection Agency (EPA), Struck said. At press time, EPA was expected by mid-December 2011 to propose a rule updating the National Pollutant Discharge Elimination System stormwater program, which hasn’t been revised since 1999. “A key component will be a new performance standard that would require new developments to capture and retain a certain amount of stormwater onsite,” Moeller said. This will create an incentive to build green infrastructure to increase infiltration and to harvest rainwater for nonpotable use around homes, he said. The proposed rule also would establish standards for redevelopment of existing sites. “This will really change the way we do things,” Moeller said. EPA intends to finalize the rule by November 2012.
Meanwhile, EPA released new guidance on CSOs in an Oct. 27 memorandum. The new guidelines promote integrated planning for wastewater and stormwater projects that the agency says will lead to more-sustainable solutions, such as green infrastructure. The policy outlined in the memorandum is supported by the U.S. Conference of Mayors (Washington, D.C.).
— Janet Pelley,
© 2012 Water Environment Federation. All rights reserved.