At least that’s the hope of the Milwaukee Metropolitan Sewerage District (MMSD), which has unveiled an ambitious plan to use green infrastructure to capture the first 12.7 mm (0.5 in.) of rainfall that hits its service region’s impervious surfaces. This amounts to about 2.8 million m³ (740 million gal) of stormwater every time it rains, or almost 1.5 times the storage capacity of the deep-storage tunnel the district completed two decades ago.
MMSD’s new Regional Green Infrastructure Plan, which provides the blueprint for achieving this goal by 2035, is a key component of the utility’s overall vision to eliminate overflows and backups while improving local water quality. MMSD serves Milwaukee and 27 other municipalities in an area covering 1065 km2 (411 mi2).
The district’s “first half-inch” goal may be
new, but its efforts to support local businesses and communities that implement
green infrastructure best management practices (BMPs) date back more than a
decade. “The difference now is that we can track the volume of water these BMPs
are capturing,” said Karen Sands, manager of sustainability at MMSD.
This is possible because MMSD collected data
on and mapped the 236 km2 (91 mi2) of roads, buildings,
parking lots, airports, and other impervious surfaces within its seven
watersheds. Its green infrastructure plan includes, among other things, an
analysis of how this land is used, the costs and benefits of the BMPs that
might be used to capture runoff from it, and the volume of stormwater each type
of BMP is designed to retain.
All this information is helpful as the
district goes about the business of prioritizing future projects and making
funding decisions, Sands said.
The district’s analysis, for example,
compares the capital costs of various BMPs relative to the storage capacity
they create. It found that native landscaping and soil amendments deliver the
most bang for the buck, with storage costing an average of only $0.05/L
($0.19/gal) and $0.07/L ($0.28/gal), respectively, compared to green roofs
($1.25/L [$4.72/gal]), cisterns ($1.19/L [$4.51/gal]), and stormwater trees
($1.29/L [$4.89/gal]), according to the plan. Porous pavement, rain barrels,
rain gardens, and bioswales all cost less to implement than the existing
deep-tunnel storage system, which cost $0.64/L ($2.42/gal).
Off to a
While the 2035 goal is
voluntary, MMSD has at least some regulatory incentive to make these
investments. Earlier this year, it became the first wastewater utility in the
nation to have green infrastructure included in its pollution discharge permit.
To comply, it must add 3785 m3 (1 million gal) in green
infrastructure capacity each year for the next 5 years.
To reach its 2035 goal,
the district knows it will have to go well above and beyond the permit
requirements. In July, it announced a proposal to contribute $1.2 million
toward the construction of cisterns, porous pavement, and other stormwater
runoff controls on 13 public and private projects designed to capture more than
12,500 m3 (3.3 million gal) of stormwater. The project owners also
bear part of the cost.
“So far, our green
infrastructure program is based on ‘carrots,’ and it only applies to
developments of a certain size,” Sands said.
Current rules require
developers to limit runoff to predevelopment levels on projects that increase
impervious surfaces by 0.2 ha(0.5 acre) or on any development of
0.8 ha(2 ac) or larger.
“Now we have to start asking if we should
broaden our reach to smaller developments and also to look at ‘sticks’ for
noncompliance,” Sands said. An ad hoc committee is being formed to
establish these policies, she said.
“Municipalities here are excited about green
infrastructure but worry that the upfront costs and maintenance are sometimes
higher [than more traditional approaches],” Sands said. “Our triple-bottom-line
analysis shows terrific benefits — but the benefits don’t always go back into
the same pocket that the upfront costs came from. Our job now is to figure out
how to achieve economies of scale and change the culture so that these
approaches become more affordable and accepted.”
—Mary Bufe, WE&T
Frankenstein knew about wastewater …
graduate student builds an artificial colon to simulate how bacteria in
wastewater would behave in a natural environment
Marcus, a former graduate student at the University of California–Riverside,
knew that if he wanted to understand the impact bacteria in wastewater have on
groundwater and how bacteria behave in microbial communities with
microorganisms, he had to replicate the natural environment in which the
bacteria exist. In the past, scientists typically studied bacteria in an
isolated environment under ideal growing conditions, but Marcus knew this
wasn’t the best approach. He knew it in his gut, which is why for his
experiment he built a human gut, incorporating a synthetic human colon, a
septic tank, and groundwater.
A fellow graduate student at the university,
Alicia Taylor, was inspired by Marcus’s research and is using the same system
to determine how nanoparticles behave in a similar environment.
It’s all in the
“The first thing I did was background
reading,” Marcus said, explaining how he built the synthetic colon. “I’m not a
gastroenterologist. I needed to know what the colon does and how it functions.”
After doing research, Marcus said he knew a
few major processes had to be included in his synthetic colon: dehydration
along the pathway so that waste can become solid and the water could be
redistributed, microbial ability to metabolize metabolites, and facilitated
transport of these metabolites to the body.
The microbes in the colon were taken from a
human fecal sample, Marcus said. And three times a day, he “fed” the colon.
“I used colon media found in literature that
would replicate a close approximation to the Western diet,” Marcus said. It was
composed of 20 different ingredients, “stuff that’s not digested by the body
before it heads to the colon,” he said.
After conducting his experiment, Marcus found
that the Escherichia coli strain in the microbial community may be less
mobile in aquatic environments and more prone to forming biofilm than the same E.
coli strain in an isolated environment, according to a University of
California news release.
The E. coli therefore could remain
longer in the environment, since biofilm provides a refuge for all
microorganisms within it, the release says. When the biofilm matures, it sends
out bacteria to colonize another surface. Thus, the bacteria could survive in
the environment for longer periods.
“This means that pathogens could potentially
linger longer, and over a long period of time travel greater distances in the
groundwater,” Marcus said in the release.
Marcus published his findings in the journal Applied
Environmental Microbiology and has since graduated. “I’m headed to France
to study synthetic biology,” he said.
Meanwhile, back at the University of
California, Taylor is continuing to work with the system Marcus helped create.
She is conducting her own research. She said she also is interested in
microorganisms and also thought it was important to study them in the actual
microbial communities rather than in isolation. But instead of focusing on
bacteria, Taylor chose nanoparticles as her area of study.
“Nanotech is really booming business,” Taylor
explained, and nanoparticles are in many consumer products, from makeup to
cereal. She said she was interested in seeing how they affect microbial
communities inside the gut.
For her experiment, Taylor is using titanium
oxide, zinc oxide, and cerium oxide nanomaterials. Titanium oxide and zinc
oxide are anticipated to be prevalent in groundwater, she said.
Taylor ran the nanoparticles through the
artificial colon. Also, using the same system, she will conduct a study of what
happens to microbial communities in septic tanks when nanoparticles go down the
drain, much like makeup in the shower.
Taylor said she wants to see if nanoparticles
affect the microbial communities in septic tanks. If they do, “you could then
postulate that the septic tank can’t adequately function,” she said. “The
contaminated water could enter the groundwater.”
Taylor says she still has to conduct a few
more control studies before she finishes her research. She said she would be
ready to publish her findings by next spring.
the green for blue?
financing structures hold promise for attracting private capital, but some
investors see higher risks
shortfalls in the water sector are continuing to limit the ability of
communities to initiate new projects and complete needed water and wastewater
upgrades, causing ever-widening infrastructure and regulatory gaps and creating
higher demand for new financing sources. With options limited from the federal
level and municipal budgets squeezed, private equity increasingly is seen as a
real solution for filling this need and is anticipated to play a much larger
role in the future for water infrastructure investing.
In line with this projection, public–private
partnerships have been a growing trend in the water quality industry, but now —
beyond financing new facilities through these arrangements — entire programs
are being structured around alternative financing models that make use of
private capital. However, despite the significant emerging opportunities for
private equity to participate in the water sector, some investors are growing
cautious in regard to expanding risks facing water utilities.
A new approach
to public–private partnerships
Prince George’s County, Md., has developed a
new public–private partnership model based on a long-term programmatic approach
for facilitating stormwater management retrofits. The initiative is being
implemented in response to a regulatory mandate to meet Chesapeake Bay total
maximum daily load regulations and retrofit approximately 3200 ha (8000 ac) of
uncontrolled urban development for improving water quality by 2025.
The model incorporates an innovative
design–build–operate–maintain–finance structure in which program
responsibilities, risk, and upfront program financing will be transferred to
the private partner.
“We turned to this type of public–private
partnership structure because of the scale and time constraints associated with
our mandate,” said Larry Coffman, deputy director of the Prince George’s County
Department of Environmental Resources. “A traditional governmental approach to
implementing this type of capital program would be too inefficient to complete
Under the programmatic model, private
partners would provide all initial capital costs and act as general contractors
in partnership with the county, which would then pay private partners a monthly
fee that would include debt service and operations and maintenance costs.
In seeking private capital, Coffman said the
county is not simply looking for large equity institutions but also is
exploring opportunities to work with local lenders, including social–economic
financing groups that invest in sustainably orientated businesses. “We are not
interested in working with equity groups that are after quick high-rate
returns,” Coffman said. “Instead, we want to attract investors that are more in
line with pension funds, with reasonable long-term rates. These standards are
important in establishing a sustainable financing model.”
An added benefit of this
approach is the opportunity to create an economic stimulus, including new jobs
and business development. “We want to use the program to benefit the local
community. It is difficult to see the potential for economic development
through the typical government procurement process,” Coffman said.
Higher risks in
Although the municipal water sector,
including water utility bonds, traditionally has been regarded as a relatively
safe, longer-term investment, issues associated with water security, drought,
and aging infrastructure are triggering increased concerns about the future
stability of this market.
A recent report by nonprofit organization
Ceres (Boston) urged caution and warned of future potential risks to water
infrastructure investors because of intensifying water stress, declining
revenues, and uncertain water demand.
The report, Water Ripples: Expanding Risks
for U.S. Water Providers, recommends that utilities revise the way they
project future water demands and that they move carefully before embarking on
pipelines, reservoirs, and other major water infrastructure projects that could
create financial risks for investors.
“Many investors still view this sector as an
essential service provider and lower-risk, but over the last couple of years,
more water utilities have had their credit ratings downgraded or put on
negative watch due to water stresses and supply issues stemming from drought,”
said Sharlene Leurig, senior manager of insurance and water programs at Ceres
and the report’s author.
Declining water demand was cited as another
risk factor. “Across the country, water systems are seeing a persistent drop in
household water consumption,” Leurig said. “This is a very challenging
environment to operate in, especially with the knowledge that utilities need to
finance the improvement of their infrastructure networks.”
Leurig recently helped prepare a letter on
behalf of a group of investors managing $40 billion in assets that was sent to
the National Federation of Municipal Analysts (Pittsburgh), requesting that
water utilities be held to more-stringent disclosure requirements on issues
relating to supply security, demand management, asset management, and water
Matt Diserio, president of Water Asset
Management LLC (New York), one of the investment groups signed to the letter,
said the fact that these water-related risks are starting to be more broadly
recognized represents an opportunity to improve water supply reliability and
infrastructure quality. “Increased transparency is an important aspect to the
21st century economy,” Diserio said. “Other industries are held to these higher
standards, and the water sector should not be any different. Many companies and
assets will stand to benefit from a higher degree of transparency in this
While water-related stresses and
infrastructure liabilities pose significant risks to financers, these same
issues also can represent investment opportunities, said Steven Kloos, a
partner at venture-capital firm True North Venture Partners (Chicago), which
focuses on early-stage investment opportunities in such industries as water,
energy, and waste.
“Water scarcity can be [a] driver for a young
company with a unique water solution,” Kloos said.
Due to the declining state of many water
infrastructure and delivery systems, Kloos also is seeing higher demand for
“smart water solutions that can do things like detect leaks before they become
bursts, helping municipalities avoid huge capital expenses,” he said.
“These data-driven solutions
target water system inefficiencies and reduce losses from nonrevenue water.”
— Jeff Gunderson,
next $100 billion
U.S. drinking water needs loom, experts mull best ways to focus future
Drinking water infrastructure throughout the U.S. will
require $384.2 billion in improvements through 2030, according to the results
of the fifth Drinking Water Infrastructure Needs Survey and Assessment released
in June by the U.S. Environmental Protection Agency (EPA). Meanwhile, the
Johnson Foundation (Racine, Wis.) recently asked a panel of experts about ways
to rethink existing approaches to water infrastructure in light of climate
change. Specifically, the experts were asked the question, “How to spend the
next $100 billion?”
Water needs through 2030
Conducted every 4 years, the EPA assessment documents
the 20-year capital investment needs of the roughly 52,000 community water
systems and 21,400 not-for-profit noncommunity water systems that are eligible
to receive funding from the Drinking Water State Revolving Fund (DWSRF). The
current assessment, which covers the period from 2011 through 2030, only
addresses infrastructure needs eligible to receive assistance from DWSRF and so
excludes capital expenses associated with such projects as dams, raw-water
reservoirs, future growth, and fire protection. The overall total of $384.2
billion tracks closely the results of EPA’s last assessment, which found that
water providers would require $379.7 billion from 2007 through 2026.
By far, the greatest demands pertain to transmission
and distribution projects, which require $247.5 billion, or 64% of the total
national needs, according to the assessment. Treatment-related infrastructure
is the next largest category, representing $72.5 billion, or 19% of total
needs, followed by storage ($39.5 billion, or 10%) and source requirements
($20.5 billion, or 5%). As for needs among water providers, the assessment
notes that medium-size community water systems — those serving 3301 to 100,000
people — have the greatest needs, totaling $161.8 billion. Large community
water systems serving more than 100,000 people have the next largest needs,
amounting to $145.1 billion. Small community water systems serving fewer than
3300 people require $64.5 billion through 2030.
To ensure their sustainability well into the future,
water providers must account for climate change when deciding how to invest in
their systems in the future, said Kala Vairavamoorthy, professor and dean of
the Patel College of Global Sustainability at the University of South Florida
(Tampa). He was one of the experts who responded to the question from the
Johnson Foundation about the next $100 billion.
“The strength and frequency of extreme weather events,
coupled with increased variability and unpredictability in the availability and
reliability of water resources, is turning our old models and assumptions on
their heads,” Vairavamoorthy said. Therefore, a “new vision of water
management” that “adapts human demands and structure to the dynamics of natural
systems” is needed, he said.
To this end, water systems must be resilient,
reliable, efficient, and flexible, Vairavamoorthy said. However, smaller,
decentralized systems are more likely to embody these traits than are the
large, centralized systems that predominate in urban areas today. For this
reason, “we need to upend the current paradigm and invest more in smaller,
distributed urban water systems,” Vairavamoorthy said. Because they are more
diverse in nature and able to contain failures to more localized areas,
distributed infrastructure decreases risk and vulnerability to extreme events
while reducing energy requirements, he said.
Keeping the risks associated with climate change in
mind, water systems should employ a “portfolio strategy” to guide future
investment decisions, said Paul Fleming, manager of the climate resiliency
group at Seattle Public Utilities, in response to the Johnson Foundation’s
Under this method, “nonstructural approaches are
evaluated on par with traditional, structural approaches to determine what mix
of strategies best addresses climate risks in an interconnected world,” Fleming
said. “This requires investing in improved planning and assessment methods and
evaluation techniques to help identify and analyze the varying costs and
benefits of a broad array of approaches and to assemble them into viable and
More planning needed
G. Tracy Mehan, principal at The Cadmus Group (Boston)
and a former assistant administrator of EPA’s Office of Water, agreed on the
need for improved planning of infrastructure spending.
“Some portion of that $100 billion should go to
developing and implementing top-notch asset management plans to guide
investments over time in a cost-effective and timely manner, including the most
basic question as to what assets does a given utility need,” Mehan said in an
interview with WE&T.
Infrastructure improvements that enable water
providers to better tailor the quality of water to the intended use should
receive serious consideration as part of any discussion of optimizing water
systems, said Alan Vicory Jr., principal at Stantec (Edmonton, Alberta), in an
interview with WE&T.
For example, as communities develop new infrastructure
or upgrade existing systems, they should try to avoid having to treat all water
to drinking water standards, regardless of how the end product is likely to be
used, Vicory noted. “We have to get away from that,” he said.
— Jay Landers,