Industrial sites have been slow to install green infrastructure. Years ago it didn’t have the track record of success that it has now. Industrial sites often have confined spaces or impervious areas that would have to be removed, adding extra cost. But industrial sites and green infrastructure can be a cost-effective and efficient combination, as the following projects have proven.
TOTE Terminal
The Totem Ocean Trailer Express (TOTE) terminal at the Port of Tacoma, WA, is a pioneer in using green infrastructure–specifically rain gardens–on an impervious industrial site. The company’s three rain gardens, installed in 2011, treat runoff from 10% of the surface area at the terminal.
TOTE ships household, military, construction, and other types of cargo and vehicles from Tacoma to Anchorage, AK. The company’s specially built ships are large enough to carry dozens of cargo-laden tractor trailers (Roll On, Roll Off) and more than 200 vehicles below the top deck.
TOTE’s site at the Port of Tacoma covers 35 acres. When a representative of a local environmental group, Citizens for a Healthy Bay, visited the site, she met with Rand Lymangrover, TOTE’s terminal, environmental, and security manager. Lymangrover explained the challenges involved in managing stormwater on an industrial site. The representative suggested that he consider installing rain gardens.
“The more I thought about it, the more it started to make sense,” says Lymangrover. “The thing about rain gardens, especially in an industrial area–especially in the Puget Sound area–is that we’re so sensitive to runoff.”
Small rain gardens were installed at the Port of Tacoma’s Totem Ocean Trailer Express terminal.
Recalling that before the area was built up and the land covered with impervious surfaces, the rain naturally infiltrated onsite, Lymangrover realized that with rain gardens, “we’re kind of reverting back to what the area used to be like.”
After removing layers of asphalt that totaled a foot deep, the TOTE rain garden installers found that the soil beneath was Puyallup Rim Alluvial. “That’s basically a very sandy soil,” explains Lymangrover. “It percolates very well, so you don’t need a large area rain garden to treat the runoff.”
Two of TOTE’s rain gardens are adjacent to each other. They each measure 120 feet by 3 feet. The third rain garden is 80 feet by 20 feet and has an underdrain that goes into the company’s sewer system.
“The other two go directly into the soil. In a big storm they’ll fill up, but in an hour or two after it’s over the water has infiltrated,” says Lymangrover.
The maintenance section of TOTE’s terminal contributed a lot of pollution to the site’s runoff. Tires, wheels, and other equipment were exposed to rain while being stored there.
“Our problem is dissolved metals. We don’t have turbidity, oils, or grease,” explains Lymangrover. “This is where we struggled. The water looked clear, but did not meet our dissolved metals benchmark.”
TOTE officials tried different strategies to manage this pollution, including commercial products and systems. Nothing was ever successful except the rain gardens. “The rain gardens brought us below the benchmark,” states Lymangrover.
The cost of traditional gray infrastructure “was pretty scary,” says Lymangrover. “Some treatment systems cost $250,000 to $400,000. That’s just the initial expense of installing them.”
TOTE’s three rain gardens cost $8,000 each, a total of $24,000. Lymangrover says the cost would have been higher, but “an engineering company donated its services. The port helped with permitting and a place to dispose of the asphalt. The Garden Club of Tacoma donated plants.”
Installing the rain gardens was done by volunteers. They included TOTE employees, longshoremen, stevedores, and environmental group members.
When TOTE’s first rain garden was installed in April 2011, Lymangrover noted the company “achieves three objectives with this rain garden. It improves stormwater quality, it demonstrates to others in the industry that it works, and it helps beautify our site.”
TOTE’s rain gardens do require some maintenance. “Some of the plants have grown to over 6 feet tall,” says Lymangrover. “Every fall we trim them.”
He admits he was surprised by how beautiful the rain gardens are. “I really didn’t think about it, but those areas were pretty doggone ugly before. Now they’re attractive, with the plants and birds.”
TOTE is also doing some public education about managing stormwater. More than 100 groups of people have come to see the company’s rain gardens.
“City of Tacoma officials came to see the gardens, and now they’re installing rain gardens on main avenues in the city,” says Lymangrover.
River of Dreams rain garden at the Grand Rapids wastewater treatment facility
Three Rivers
The Environmental Service Department (ESD) in Grand Rapids, MI, has three rain gardens. The first one was installed to solve a drainage problem at the department’s Sewer Maintenance building.
An intern named this rain garden River of Stars, from a line in a song. She was part of the Western Michigan Environmental Action Council (WEMEAC), which works with the rain gardens.
Before the installation of the rain garden, stormwater runoff from surrounding pavement and the roof of a nearby building pooled onto the yard that surrounds the building. The standing runoff and resulting mud made mowing all but impossible. Mosquitos flocked to the area.
The solution was the 25- by 35-foot rain garden, created with help from Rain Gardens of West Michigan and RiverMaid Design. The plants used were mostly mature, full-sized perennials and plugs (one-year-old perennials). The combination of native prairie species, grasses, and other landscape plants make this garden as beautiful and functional. River of Stars is a popular site with ESD employees for their lunch breaks.
Installed in 2008, Grand Rapids ESD’s second rain garden is called River of Dreams. That’s because “we’re a river kind of city and we wanted to stay with the river theme, and this is our dream garden, from the roots up, large enough for lots of different species” says Sandy Buchner, an ESD chemist who also conducts tours of the rain gardens.
The River of Dreams is located at the Wastewater Treatment Facility. This 75- by 75-foot rain garden is situated on an old tank site and manages stormwater from 1.5 acres of the plant’s 56 acres.
Buchner says that River of Dreams is “a demonstration garden, built with that in mind, to encourage other people to put in their own rain gardens. School groups tour through and then put in their own rain gardens. We raise extra plants there, as a nursery. WEMEAC volunteers will take them out and donate them.”
During the garden’s first year, there were three rain events that exceeded a once-in-75-years storm. Even during these storms, the garden captured and infiltrated 100% of the runoff in this area.
Grand Rapids’ typical rain event is 1/2 inch of rainwater. The average rainfall of 37 inches means that 1.5 million gallons of untreated storm water are diverted to the rain garden. That runoff would otherwise have gone into the Grand River.
Just one week after the first planting, on July 3, 2008, the new rain garden was put to the test with a 50-year storm event. The Wastewater Treatment Plant received 4.73 inches of rain in 1 hour and 13 minutes. That amount of rain meant that more than 189,000 gallons of stormwater flowed into the rain garden in just over an hour. But the standing water only lasted a day or two, and the native plants all survived.
“It drained, even without the plants [having grown],” says Buchner. “The soil was well-aerated. No heavy equipment was there while it was being built that would have compacted the soil.”
The cost of the River of Dreams rain garden was about $35,000. The estimated cost for gray infrastructure to serve the same area approached $60,000. The gray infrastructure would have routed the stormwater to the Wastewater Treatment Plant’s final effluent channel, impacting the quality of the plant’s final effluent.
The River of Dreams rain garden contains 29 different Michigan native plant species. It was engineered to handle the stormwater from the surrounding pavement and the rooftop of the nearby storage building. Engineers worked to design and modify the soil composition in the area to drain quickly, considering they were managing such a large area of impermeable surface. The roof of the new storage building drains into the rain garden. The storage building has eight downspouts that feed directly into the center of the garden.
The third rain garden (River of Two Cities) is smaller than the other two, but has five infiltration basins. The rain garden and infiltration basins provide 100% of the stormwater management for 11 acres of the plant’s grounds.
The cost for this infrastructure was $88,750 and was less expensive than the estimated $774,950 for gray infrastructure. The gray infrastructure would have included a lift station to pump the stormwater into the final effluent channel and would also have affected the quality of the plant’s final effluent.
This project was part of the Grand Valley Regional Biosolids Authority (GVRBA), which is a partnership between the City of Grand Rapids and the City of Wyoming to address biosolids using a regional approach. Installed in August 2009, the River of Two Cities rain garden is located at the GVRBA Dewatering Facility. This facility is a LEED silver-certified building and the first LEED building for the Grand Rapids ESD. Stormwater management strategies earned some of the points toward the LEED certification.
The site has many retention areas for the stormwater, and collectively the sites are named River of Two Cities Rain Garden. The name also refers to the two cities involved, both on the Grand River. Both cities needed a facility for handling solid waste (biosolids) from their water treatment facilities. The combined facility saves money for both cities.
The solid waste is pumped to a single facility and handled in an environmentally friendly manner, by disposal in energy-producing landfills or land application. The energy-producing landfills mix biosolids, which are rich in microorganisms, with landfill waste to assist in decomposition and increased methane gas production. The landfill then captures the methane gas and converts it to a usable energy. Mixing biosolids with landfill waste has proven to increase decomposition rates. Landfills can therefore be used for more years, and less space is needed for them.
The River of Two Cities rain garden is composed of 13 depressions. One depression on the site has modified soil layers for effective drainage and has been planted with 10 Michigan native plant species. Other depressions have been engineered for retention and were planted with Michigan native grasses and Michigan native wildflowers in 2010.
The depressions are interconnected, allowing for water to equally flow to each area. Sections of plants, including Joe-pye weed, Indian grass, switchgrass, and big blue stem, seem to flow into each other, too.
One hundred percent of the site’s stormwater is directed to the rain garden and managed onsite. The site is approximately 4 acres, and the rain garden manages three million gallons of stormwater annually.
As much as possible, the three ESD rain gardens were planted with plugs. They cost only a dollar a piece, much cheaper than mature plants.
Buchner has been pleasantly surprised at “how quickly the little plants mature.” She says, “We were able to have the gardens fill in fast, even while keeping them low cost. The rain gardens started working right from the beginning.”
Grand Rapids ESD’s three rain gardens provide beautiful green spaces, control stormwater pollution, and are less expensive than traditional stormwater treatment, collection, and pumping facilities.
The Port of Tacoma’s “rain garden in a box” manages runoff using a 300-gallon food-grade plastic tote.
Area for construction of a larger four-cell rain garden at the Port of Tacoma
Port of Tacoma
The Port of Tacoma is using a specialized type of rain garden to manage runoff, a “rain garden in a box,” says Anita Fichthorn, environmental project manager of water quality for the port. She adapted the design for the box from one in use at the Port of Vancouver. Each box is a 300-gallon food-grade plastic tote.
The tote/box measures 3 feet high, 3 feet wide, and 3 feet deep. Several 2-inch perforated pipes were placed in the bottom of the first three boxes, surrounded by drain rock. Filtered runoff flows through these pipes and discharges into storm drains. Subsequent boxes have been installed without the pipes (a savings) and work just as well, Fichthorn says.
The stormwater is filtered as it moves through a bioretention soil mix in the top of the box. Developed by Washington State University professor Curtis Hinman, the mixture of 60% sand and 40% compost imitates soil in nature, slowing the flow of water and filtering out pollutants.
As it becomes filled with pollutants, the soil mix will eventually have to be replaced. To extend the soil mix’s effectiveness, Fichthorn adds deciduous plants so that some pollutants can be removed through biological uptake.
“They’re still going. This is the third year for one of our boxes,” says Fichthorn. “The concentrations [of metals] go up a bit, but not above the benchmarks” set by the state’s strict environmental regulations.
Many industrial facilities near the port struggle to meet those water-quality benchmarks set by the state of Washington. High levels of zinc and copper in stormwater runoff are the most common culprits.
“We have some of the most stringent stormwater regulations [in the country], so we’re trying to eliminate ambient deposition,” says Fichthorn. “We also have saltwater corrosion affecting metal roofs, but even on plastic surfaces, there is ambient deposition.”
She adds, “We’re trying to eliminate pollution closer to the source. At or near the source, it’s cheaper to eliminate. Closer to the water, it’s more expensive to eliminate.”
The Port of Tacoma requires vinyl covering on all chain link fences. Uncoated galvanized steel is not permitted for roofing or other materials that come in contact with stormwater.
When Pierce County Terminal’s (PCT’s) zinc level tested above the approved levels too many times in 2010, the state required the terminal to find a treatment solution. Through sampling, Fichthorn identified the maintenance building’s metal roof as a primary source of zinc on the terminal area. In the summer of 2011, as a test project, PCT installed three port-built boxes at downspouts on the building. Initial results showed that the downspout rain garden boxes remove up to 99% of metals, particularly zinc and copper, from the rainwater that flows off the building’s roof. Now the boxes are on 12 of the building’s 16 downspouts.
“The results at PCT were amazing,” says Fichthorn. “We have an average of 1,000 micrograms of zinc flowing in to the system and 17 micrograms flowing out at the discharge point.”
The rain garden in a box (which is recycled) costs only about $100 to make. It offers flexibility for composition and is portable.
Other tenants at the Port of Tacoma, including Progress Rail and the TEMCO/Cargill grain facility, have these rain gardens in boxes. Seven of the big terminals have buildings, and several of them have installed rain garden boxes. “We will build them for our tenants,” says Fichthorn.
Fichthorn has another interesting piece of green infrastructure managing stormwater runoff at the Port of Tacoma, an enlarged variation of the rain garden box. This stormwater structure measures 600 feet long and 24 inches deep and has rocks along the bottom. This big box rain garden contains the same plant mix used in the smaller boxes (juncus, fescues, and grasses) plus bamboo, which was added to increase the uptake of chemical oxygen demand (COD). The garden has four different cells.
“It’s a biofiltration system. We collect and discharge stormwater. Stormwater is pumped into the first cell, which handles the solids. It has pea gravel. Then the runoff flows by gravity into the second cell, which is all sand and biochar, for COD,” explains Fichthorn.
Activated carbon is expensive–$1,900 for a cubic yard–so Fichthorn and her consultant experimented with different types of carbon sources to find one that worked well with the sand. One problem is that biochar is light and fluffy, so the heavier sand keeps it in place.
The third and fourth cells both contain the bioretention soil mixture of sand and compost. Stormwater is pumped up into the third cell and then flows by gravity into the fourth.
During construction
Runoff moves by gravity flow and pumping through the different cells of the port’s bioretention system.
The port will soon also have a commercially built modular wetland. Construction on the more-than-40-foot structure should be completed in the fall of 2014.
“It’s on our north intermodal yard, a rail switching yard. Containers off of ships are placed over the top of rail cars, by straddle carriers,” says Fichthorn.
The wetland is situated on the bank. It consists of four flow cells, a type of treatment train. The cell in front is for solids. Stormwater flows through plant roots and growing media and discharges to Commencement Bay, at the end of the pier.
“Trying to modify them to work in an industrial application has been a challenge, because they will be constructed close to the water,” says Fichthorn.
She is always searching for ways to improve stormwater management and reduce pollution before it reaches the bay. Permeable pavers, often used for parking lots and in other parts of industrial sites, aren’t strong enough to withstand the weight of heavy shipping containers being dropped on them. Pavement at the port is 12 to 18 inches thick in some places.
“Our real success has been doing pilot studies,” explains Fichthorn. She may try putting a long narrow rain garden under a fence line. “Galvanized fence line is a big source of zinc in stormwater.”
Green roofs are popular in industrial stormwater management, but would likely be too heavy for buildings at the port. Instead, Fichthorn would like to try going vertical with a pilot green wall, if she can secure the funding.
Noting how the Port of Tacoma works with its tenants on environmental compliance, Fichthorn says, “On the development side, a municipal stormwater permit requires a basic treatment plan to remove solids. But once a facility is built, industrial stormwater permits are required. They have benchmarks to be met for metals.”
The port’s goal is “to integrate these stormwater permits [for tenants]. We can match our treatment system menu and the last three, four, five years of sampling data to figure out what their treatment requirements will be.”
Benchmarks are measured on a quarterly basis. If tenants fail to meet benchmarks for three quarters in a calendar year on levels of metals in runoff from their facilities, then they trigger a Level Three Corrective Action by the state of Washington.
Fichthorn notes, “It’s less expensive to meet benchmarks right away, during a development action, instead of doing an expensive retrofit less than a year into a new facility.”
These examples show that green infrastructure has a place in managing stormwater on industrial sites. It manages stormwater effectively and often less expensively than gray infrastructure does.
Green Incentives
Michael Pronold, environmental program manager for the Bureau of Environmental Services (BES) in Portland, OR, says that municipal requirements have spurred the use of green infrastructure on all types of sites.
“Under our local requirements, any new development has to go through a hierarchy for stormwater management. One of the first things they have to do is to evaluate the use of green infrastructure, whether it’s a commercial, industrial, or residential development,” he explains. “They have to look at it and show us why they can’t include it.”
He adds, “Some industrial sites are using green infrastructure to meet provisions in state stormwater permits, such as Oregon’s.”
Portland gives owners of industrial, commercial, and residential property a financial break on the 30% of their stormwater fees related to the amount of stormwater managed on the property. Pronold says this is another incentive for installing green infrastructure.
Swales are more prevalent on industrial sites than other types of green infrastructure. However, Pronold says “a good number of sites are into using rainwater harvesting, which, by EPA definition, is green infrastructure.”
Examples of industrial sites in Portland using this approach include a company that shreds old tires and one that crushes and recycles old cars. Both capture rainwater to use for cooling the shredders so they don’t overheat.
“Even with concerns about containment on brownfield sites you can still implement green infrastructure, such as lined swales or planters, so the runoff doesn’t infiltrate,” says Pronold. He notes that EPA offers publications and website information on using green infrastructure on brownfield sites.
