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Copy and Paste This Permanent Link:http://www.stormh2o.com/buyers-guide-2010/keeping-lid-on.aspx

Additional Article Content

• How the Device Works

Photo: Sara Cohen, Massachusetts Department of Conservation and Recreation

Nature has its ways of dealing with stormwater. Some percolates into the ground, some pools, and some makes its way to larger bodies of water; often, which route water takes depends upon the state of the soil and the plant life growing within it. A sandy soil allows water to pass through; a clay soil absorbs only so much, then creates a muddy mess. A site containing a water-loving tree, such as a weeping willow, will eagerly drink up as much moisture as it can get, while other plants suffocate from lack of soil oxygen and resign themselves to becoming peat.

Once humans have altered a site, however, all bets are off, especially since most of our construction materials are nonporous. Therefore, a variety of manufactured products and earth-altering tactics are used to compensate for our changing nature’s status quo.

What Is LID?
“Low-impact development [LID] is an approach to stormwater management and site design that uses natural hydrologic processes to preserve or recreate that hydrology at the site level, or to meet goals,” explains Neil Weinstein, executive director of Beltsville, MD’s Low Impact Development Center, a nonprofit organization dedicated to the advancement of LID technology. “LID mimics how nature handles water. It’s a performance-based approach. Old regulations used prescriptive approaches—such as ‘achieve 80% TSS [total suspended solids] removal’—which are somewhat ambiguous. For example, what’s the incoming load? We’ve previously used generic, one-size-fits-all approaches, rather than looking at the land use and how the BMP [best management practice] responds to it.”

Photo: Best Management Products Inc. A manufactured device, such as BMP Inc.’s Snout, can trap pollutants, whether oil, styrofoam peanuts, tennis shoes, or hypodermic needles.

Is LID expensive to accomplish? “LID is most cost-effective and best performing, environmentally,” says Weinstein. “It brings a business-based approach, where we can use the most cost-effective and environmentally efficient technology for the problem. We’ve been working with Green Highways Partnership and partnering with EPA Region 3 and the Federal Highway Administration, moving stormwater into the 21st century economy. We’re looking at a watershed-based approach toward stormwater—recycling, environmental programs through greening, and conservation—where highways can be the foundation for Environmental Management Systems and watershed restoration.”

Weinstein points out that Section 438 of the Energy Independence and Security Act requires all federal facilities to meet all preconstruction hydrology for new building construction. “But this has to be a site-based approach—doing what makes sense at that site, like using permeable concrete for the right land use,” he says. “Does the site have compacted clay soil? Maybe you can’t get water to percolate back into the soil, but you can reuse that water, which creates the same results. LID gets people thinking about the process. What we tended to do before is build it and forget it; now, LID moves things into management systems, one looks at the site’s whole life cycle. Instead of just building a retention pond, you might be able to put in retention tanks and use the land once set aside for the pond. You have options.”

Rain is often fickle; some areas get too much, others not enough. “People often forget this country has a water crisis,” says Weinstein. “Stormwater is a valuable resource! It can be used for so many things, and we haven’t yet been thinking about using it for potable water. Watering restrictions pop up all over the nation during the summer; people are willing to pay for water because they like lawns and gardens. We need the freedom to use water wisely.”

Keeping more rain on each site and out of municipal stormwater systems also has benefits. “This could lower capacity, so we don’t have to build all this infrastructure,” says Weinstein. “LID is not the answer to everything, but if there’s the option for everyone taking responsibility for their own area, that’s a step in the right direction.” Many technologies can help accomplish LID’s goals: “Who’d heard of a green roof 10 years ago? Now it’s cheaper to have one, and people will build what’s cheaper, especially since many roofs are already structurally built for green roofs.”

Unfortunately, money isn’t always being put where the mouths are. “People are asking for instant answers, but the nation’s not putting money into looking into these options,” adds Weinstein. “People are fighting for research dollars everywhere. Who’s really putting R&D [research and development] into retention cells? The only way something like this gets done is if someone thinks it up in his basement.” However, ideas can, and do, come from anywhere: “Engineers are designing rain gardens. Landscapers suggest more useful plants or soil mix. We can recycle items one would never think of using for stormwater. For example, the blasting sand left over after cleaning railroad car wheels—it’s mainly iron oxides, which attract pollutants. The trouble is, maybe some of these workable ideas don’t fit standard BMP codes, and it can take years and money to change minds and codes.”

Photo: Chip Hatter Photographics This beautiful expanse of lawn can also serve as a parking area.

The Low Impact Development Center positions itself as a clearinghouse for this type of information. “We’re a nationwide group of seven people, and we have an office in California that will grow,” says Weinstein. “Stormwater has to be looked at as an economic and business model; the most effective type or design of permeable pavement in Chicago may not be the right one for Oregon.”

Weinstein believes LID has advantages. “It gives us the ability to look at things holistically, to save infrastructure. Maybe it will help create green jobs. And, although it can be implemented nationally, or state by state, it has benefits even at the local level; each ‘little’ project helps. For example, some counties are subsidizing homeowners for installing permeable driveways and rain gardens. If you explain the concept to Joe and Jane Homeowner, they can ‘get’ it; if you tell them that putting a rain garden in their yard will reduce their stormwater costs by, say, $20 a month, they’ll start digging! Having neighborhoods dotted with rain gardens is much cheaper than building new infrastructure.”

Natural State—Only “Natural” Products?
Does nature always have the “best” way of solving a problem—or, since people often caused the drainage problem, is it our job to devise a solution? An increasing number of manufacturers in the stormwater industry say “yes” to the latter: Manufactured products can do an equal, or sometimes better, job than land-based systems. To promote this message, the industry has created the Stormwater Equipment Manufacturers Association (SWEMA). Formed in 2008, the groups members are producers of stormwater devices—many of them competitors now working together to provide a voice for the industry and to lobby for such things as standard testing procedures and proper maintenance of stormwater BMPs.

“I’ve been trying to get SWEMA going for five years, since someone at a StormCon conference said it was a good idea,” says John Moll, CEO of Atlanta, GA’s CrystalStream Technologies. “I don’t mind selling against others in my field; our products are different. But the ‘enemy’ was state codes. If an engineer brings in the specs for a certain stormwater product, whether or not the item really works, it has to be put in. Our point is that no one understands how natural items, such as ponds, work—there are no maintenance records.”

Sometimes, manufactured products “don’t get no respect.” “I was asked to talk to a meeting organized by EPA Region 6,” recalls Moll. “The subject was ‘LID versus manufactured products.’ On the panel, I sat near the LID speaker, which confounded the moderator. I explained to him, ‘We are LID. How can you get lower impact than a couple manhole covers on the ground and an underground tank?’ The number one function manufactured items offer in LID design is that we save footprint. The square footage saved can be left in its natural state, such as woods.”

T.J. Mullen, president of Best Management Products Inc., in Lyme, CT, agrees that SWEMA is an idea whose time has come. “My company is a SWEMA member. We manufacture the Snout stormwater quality system, which separates out pollutants—especially gross pollutants, such as trash, floatables, and sediment—from stormwater runoff. This August, I’ll be speaking at StormCon; I think people who’ll attend are pretty much aware that structural devices are available for LID stormwater requirements. SWEMA promotes the idea that manufactured devices should receive fair and equal treatment as a method to improve the quality of stormwater runoff—just as a land-based or public domain system. In fact, there are some things manufactured items do that natural things can’t—such as skimming off trash and floatable debris, for instance.”

Photo: Filterra Bioretention Systems The grating and the shrub are integral parts of the Filterra stormwater system.

SWEMA is actually the reincarnation of a previous group, the Manufactured Water Quality Products Association (MWQPA). “To prove some of our products, we went to famed Alden Labs in Holden, MA, an independent testing lab,” says Moll. “Since we’d like to have a stormwater fairness doctrine, if we’re going to vet manufactured products, we want to make sure they meet best management practices.”

Testing, or the lack thereof, is one of SWEMA’s main concerns. “We’ve learned a lot over the years of making our products,” he adds. “We think regulators need to require testing of public domain systems, too—does a pond work better than our products? My product is not the best solution for every site; I know that—but a wet pond is not the best for every Georgia site, either.”

SWEMA is also concerned with maintenance. “When establishing the MWQPA, the first committee we organized was ‘maintenance,’” says Moll. “We sold maintenance from the first, because we realized it was the key factor in having the systems do what we’d said they’d do, and in securing customer satisfaction. One thing that always bothered us about retention ponds is why do they end up as dumps? Evidently, no one thought of maintenance, or didn’t want to pay for it. The fact that manufactured products can be cleaned gives them an advantage over natural systems. We set up our product out in the field; when it fills up, we service it and take all the collected debris out of it. Some folks say, ‘Really? We never do that with ponds.’ When I drive away after performing maintenance, the unit is like brand new. Six months later I have to do it again, but the point is, that debris didn’t get into the watershed. My CrystalStream system keeps trash and debris dry so it doesn’t rot. In a pond the stuff will rot, which will flood the area with nutrients, such as nitrogen and phosphorus. One of the most horrid things that can get into stormwater—oil—can be caught and removed by manufactured products. Ponds can’t do that.”

Moll points other potential problems with retention ponds. “Some folks avoid open water at all costs because it attracts rodents and nuisance birds, such as Canada geese, which can cause disease problems. Gas stations know there will always be some sort of spill sometime; cleaning my company’s unit is much faster and cheaper than cleaning out a pond. There’s a huge benefit in manufactured products if you want to be ‘green.’”

Manufactured units can also save water. “We’re working right now to put cisterns all over the southeastern US,” says Moll. “We go to people who are landscape-conscious and tell them if they have watering restrictions, they can save and use the roof runoff. No matter how you develop a site, it will always have three times the runoff as it did when it was just ‘nature’; if you can keep any water onsite, you catch the pollution, and, eventually, the water you save will recharge the groundwater, which supports streams in time of drought.”

Are testing protocols biased against manufactured units, or inaccurate? “When cleaning my units, I’m finding more pollutants than the regulators said would be collected, because they used automated samplers and only test the first flush,” explains Moll. “Some of EPAs protocols, such as TSS 160.2, don’t test effectively. The Federal Interagency Sediment Project (FISP) has questions about EPA’s TSS testing process; we’ve been sitting here with a bunch of assumptions on bad tests and data for so long, yet others are afraid to move forward. Who’s going to inspect things, to make sure they work?

Photo: Filterra Bioretention Systems An Inkberry shrub was planted in this unit.

“I can think of only one example,” he continues. “Montgomery County, MD, has monitored its maintenance costs for 15 years; otherwise, you can find very little information. The manufacturers of stormwater products have more testing results and more influent/effluent data.”

Moll hopes SWEMA’s member companies can answer questions and offer solutions. “We can police ourselves while we compete; we joined together to say ‘Ignorance is no excuse; it’s not us or green, its us and green.’ Measure us by what pollutants our products have caught, which we’ve carted off to landfills and kept out of lakes and streams.”

Mullen of Best Management Products emphasizes that SWEMA itself is not a testing organization. “We will be advocates—a clearinghouse of information for manufactured systems. Our goal is to offer performance data or results in a consistent and uniform manner, and ask that performance on land-based systems be presented in the same way and be subject to the same level of scrutiny as manufactured devices. What we’ve seen in the past is that a stormwater pond is given tacit approval as a BMP, but the data from a pond’s performance have not been given the same level of scrutiny as that directed toward manufactured systems. Some regulatory agencies don’t put us on equal footing as a stormwater pond; manufactured systems might be as good in some situations, especially on a site where space is tight and a pond is not feasible. We’re just trying to level the playing field through education and good science.”

Photo: Hanson Engineering Division of Dresdner Robin Burying a StormTrap system, instead of digging a retention pond, saved valuable lot space.

In many jurisdictions, Mullen explains, post-development runoff must exceed the predevelopment runoff rate. “Of course, other stipulations may apply regarding the quality of the runoff, and this is where manufactured systems can play such an important role in safeguarding the environment.”

He notes that sometimes manufactured detention systems are used on a site. “There must be some reason why the developer decided on collecting the runoff, storing it, and letting it go at a controlled rate, instead of collecting it and letting the runoff perk or infiltrate back into the soils onsite. Maybe you’re in an area where the water table is too high, and retention or infiltration may not be a viable option.

“You might store some of this stormwater in chambers or pipes to detain the water—under a parking lot, for example. Or, you could send it 100 yards or a half-mile away, where it can percolate into the soil. You have to pick and choose your methods, which are determined by the site. Sites have varying hydrology. Let’s say we know that the preconstruction discharge rate is  0.5 cubic feet per second. Based on site hydrology, the design engineer will create a stormwater detention or retention facility—either manufactured, land-based, or a combination of both—that will control the runoff, clean it up, and discharge it at the rate allowed by the jurisdiction, or have it percolate back into the soil. In any case, it’s a fairly straightforward design process, and having manufactured systems as an allowable option drastically increases the variety of ways stormwater runoff can be managed, while its quality is improved,” concludes Mullen.

Permeable Products
Asphalt or turf? For LID, the question’s a no-brainer; installing a permeable surface when one can is usually a good idea. When the area’s Mount Sinai Hospital needed a fire lane—but not more concrete—Rosenberg Gardner Landscape Architecture of Miami, FL, installed Invisible Structures’ Grasspave2. The porous paving surface allows parking, driving, and walking on a beautiful grass surface. Performing the functions of asphalt or concrete pavement, Grasspave2 does the job while providing the appearance of a lawn.

Enhancing the environment was the main objective when Kevin Neal, ASLA, project manager at Jeffrey Carbo Landscape Architects in Alexandria, LA, installed Grasspave2 at a residential estate. “A new 23,000-square-foot home was being built in DeRidder, LA. The former house had burned, and the owners knew what changes they wanted to make. They wanted to push the drive away from the house so visitors would get a nice view, whether they were coming to the house or looking out toward the grounds from inside the home. The owners didn’t want to see paving in front of the house; they chose Grasspave2 for aesthetic reasons, rather than for stormwater management. The grassy drive, which takes guests past a decorative pond and fountain, leads to the home’s front door and a grass auto court; however, for everyday traffic, the homeowners utilize a somewhat-hidden paved drive that leads to their garage.”

Invisible Structures also manufactures the Rainstore3, a plastic structure used to store stormwater underground. Made from injection-molded plastic, a single panel contains 36 vertical columns and exceeds H-20 loading (a maximum front-axle load of 8,000 pounds), allowing the construction of driving areas, parking lots, or other small structures above the system. Built-in compression fittings allow units to be easily stacked to a variety of depths up to 8 feet, 4 inches.

Photo: Hanson Engineering Division of Dresdner Robin The underground system extends from the manhole cover, in the center of the photo, to approximately the point from which the photo was taken.

When the Harvard Westlake Middle School in Beverly Hills, CA underwent a substantial upgrade, its increased footprint not only caused more runoff, but also less places to contain it. Psomas of Santa Clarita, CA, used Rainstore3 to solve the problem. “We put in under the mall area, between two buildings, where school children gather,” says senior project manager Dave Martin. “We really needed to save land, as the school is located on a hillside, and there was not much area in which to install conventional drainage storage.”

Let Trees Do Some of the Work
Because LID is designed to leave a site functioning much as it did its natural state, perhaps “nature” should be incorporated into the solution. In addition to grassy swales and the like, some manufactured devices also incorporate natural elements. When in the spring of 2007, Quincy, MA’s Kimley-Horn & Associates were called in on a project, they kept that option in mind.

Photo: Hanson Engineering Division of Dresdner Robin Site prepared for placement of StormTrap units

Photo: Hanson Engineering Division of Dresdner Robin The open bottom allows water to infiltrate.

“We were working on the redevelopment of a former naval air station that had been built in the 1940s,” says Kimley-Horn associate Brian Brewer. “The master redeveloper, LNR Property Corp., turned the 1,400-acre site into a mixed-use project, which included more than 2,800 residential units and 2 million square feet of retail and commercial space. Our first step was to spruce up the main entrance, which included widening of the road, as well as increased landscaping. We incorporated stormwater treatment features that were not there before, such as bioswales and Filterra units.”

Filterra Bioretention Systems of Ashland, VA, sells treatment systems that involve placing engineered soils in a precast concrete vault, which is installed underground. Trees or shrubs are then planted in that soil. The unit treats runoff and allows it to infiltrate, and it provides landscaping at the same time. The combination of landscape vegetation and a specially designed filter media allows bacteria, metals, nutrients, and TSS to be removed naturally. With a small footprint and a high removal efficiency for many stormwater pollutants, Filterra units can be used in highly developed sites such as landscaped areas, green space, parking lots, and streetscapes.

“Using Filterra units made sense,” says Brewer. “The site already had a curbed roadway; we didn’t want to break up curbs and put in bioswales. We installed six along the entrance section of the roadway and another six during the next phase of work. The units we installed contained Inkberry shrubs; Filterra provides plant recommendations, based upon your site and climate. Filterra also has a sizing chart, noting how much runoff each unit can take, and you can install overflow structures on either side in case you have a really large storm event.”

Brewer says the purpose of this retrofit project was mainly to improve stormwater quality. “It’s wasn’t really to achieve LID, as the stormwater eventually does reach the city’s stormwater system. But, with this entry road into the former base, we created some pleasing open space. The right thing to do was try to treat stormwater, even if it hadn’t been treated before, especially as this site is located next to wetlands—and we needed to do so in a small footprint.”

Don’t Let the Stormwater Escape—Use It!
Some LID devices offer the advantage of stockpiling rainwater, a boon for landscapes in water-rationing areas. When the Orland Park, IL police station was rebuilt in 2007, plenty of green space was included in the plans; canny designers found a way to contain runoff while also conserving rainwater for irrigation.

“The main idea was water reuse,” says Frank Childers, president of G&C Consulting Engineers in Des Plaines, IL. “We were working with SRBL Architects, which had specified lots of green space and landscaping around the station, which was a reconstruction of an old carpet warehouse. The landscape architect determined that 7,500 gallons of water would be needed yearly for irrigation on the 10-acre site. Also, Orland Park wanted the site to be LEED [Leadership in Energy and Environmental Design] certified, and it did earn a LEED Gold rating.”

The LEED Green Building Rating System, devised by the US Green Building Council, encourages sustainable building and development practices. Newly constructed or redeveloped buildings can earn points in several areas, including energy performance, materials used, and water efficiency. Depending on the number of points achieved, a building can achieve a LEED Platinum, Gold, or Silver rating.

Photo: Hanson Engineering Division of Dresdner Robin Installation of the units on a two-acre industrial site

Childers’ solution was to install a modular, precast StormTrap system beneath a landscaped area to collect runoff. “To make sure the water collected is clear of debris, StormTrap is fed only by the building’s roof drain,” he notes. “Because we’re taking only rainwater and snowmelt from the roof, the water doesn’t contain oils or salt, as opposed to runoff you’d collect from parking lots. The flat roof feeds interior downspouts, which converge into a single storm sewer, which we intercepted and diverted to the StormTrap. If the StormTrap gets filled, water then discharges into a detention pond.”

During summer dry spells, the stored water keeps the police station’s landscape green and healthy. “We installed a pressurized system connected to the StormTrap,” explains Childers. “There’s a suction pump outside on the ground so the yard workers can take the water out. The StormTrap was put in during a dry spell, and 2008 was a pretty wet year here, so, thus far, this system has taken care of all the landscape water needs.”

StormTrap, based in Morris, IL, offers the SingleTrap, fashioned from reinforced, high-strength concrete, in customized sizes ranging from 1 foot, 2 inches to 5 feet. This configuration provides a large infiltrative surface area, which allows water to filter into the soil. The DoubleTrap ranges in size from 2 feet, 4 inches to 10 feet; it can be designed to allow infiltration or can be configured as a completely contained system.

“The whole system was installed in a couple days,” recalls Childers. “In this unique application, we created a cistern for that water in an environmentally friendly way. However, this system may not be unique for long; the whole six-county area around Chicago is changing building codes and developing more cistern facilities, requiring stormwater detention.”

G&C Consulting Engineers has used StormTrap before, mostly in new facilities. “We use it where the site owner can afford it for detention. As land becomes more and more valuable, a StormTrap versus a retention pond becomes more appealing. Instead of setting aside land for a pond, they can bury the StormTrap and put a parking lot over it.”

Manufactured Items Can Leave More Natural Areas
Matt Hainzl, senior engineer with the Hanson Engineering Division of Dresdner Robin in Wayne, NJ, uses StormTrap to retain valuable square footage as well as to reduce runoff. “In spring 2008, we refurbished a rundown, two-acre industrial site for Donnelly Industries, a total rehab and building expansion,” he says. “We used StormTrap to expand the amount of useful area for stormwater management. The site also has a grass-bottomed retention basin on the property. Putting in a StormTrap accomplished the client’s goals, as there wasn’t enough usable space on the surface. Of course, as this was an old site, before we did the redevelopment there was nothing channeling stormwater. Everything used to flow offsite with no treatment at all; however, we were required to bring the site up to current standards, which had been revised
in 2004.”

The StormTrap catches only roof runoff. “The StormTrap, which has 4,500 cubic feet of storage, has an open bottom; water infiltrates into the sandy-loamy soil. The unit should be able to handle all roof runoff, unless there’s a 100-year storm,” says Hainzl. “Of course, the water can run off to the retention basin, if needed. But whereas the basin doesn’t do anything with sediment, the StormTrap settles out anything that might get in the water.”

Hainzl’s firm uses StormTrap in many area projects. “It was our first choice for this project; it’s easy to install, and we always get great support from StormTrap’s staff. Plus, because the various pieces are individually sized, you can make a smaller unit. We used 18 precast sections and shaped them to fit the site.”

Does Hainzl envision more LID-friendly projects in the future? “Yes—municipalities are all for it, and developers want to get everything they can on their sites. A unit such as StormTrap accomplishes both tasks.”

Prevent Roof Runoff Before It Starts
Roofs are a major source of runoff. What if a roof could be created that actually absorbed runoff? Green roofs do just that. Grand Valley State University (GVSU) in Allendale, MI, chose that option on a recent building addition.

“As an institution of higher learning and leadership, as well as a public university supported by tax dollars, Grand Valley State University believes it has a responsibility to practice sustainable development,” says Brad Newman, GVSU’s project manager for facilities planning. “One way we accomplish this is by building for LEED certification when undertaking new construction or major renovation projects. By doing so, we help ensure the balance of the ‘triple bottom line’ factors—people, places, and prosperity—that characterize sustainable development, while modeling behavior needed from all businesses, institutions, and individuals.

“Sustainability is also an important part of Grand Valley’s curriculum and campus culture,” he continues. “Because we believe they contribute to the practice of achieving sustainability, we’re very interested in green roofs at GVSU for several reasons: they’re an aid to stormwater management; they provide a pleasing aesthetic solution to the viewer, as opposed to a white roof that will soon discolor; and, to some degree, their added materials help improve energy performance.”

During the summer of 2008, GVSU installed modular green roof systems from LiveRoof of Spring Lake, MI, on its new MAK Unit B addition, which totals 6,600 square feet at two locations. “We selected the LiveRoof to install a green roof that was already green, as opposed to waiting for other green roof products to take time to develop green growth.”

Each LiveRoof module contains full-grown plants when it arrives at the job site. The prevegetated modules discourage weeds; other systems may require three or more years of intensive care for plants to become established. Well-established LiveRoof plants and roots create an instantly functional green roof, which can be maintained for as little as $0.15 to $0.30 per square foot. GVSU’s LiveRoof modules contain sedum plants, which flower in various colors, so the roof changes color with the seasons.

Plants, soil, and the water they absorb are weighty; any problems? “Installation went very smooth and on time,” reports Newman. “The weight of the modules was calculated by our structural engineers during design development so that the right steel was ordered for the project. Some structural analysis was performed to look at various additional locations for additional installs. For the most part, the roof modules have indicated they will be somewhat maintenance free. The fast install was a great plus during project-completion crunch time. For maintenance, we’re performing various inspections, soil testing, and irrigating when hot, dry weather persists, and mowing is recommended in the fall.”