Removing sediment and trash from stormwater and, eventually, from natural waters can often be a challenge. The best first step in this task is to catch the unwanted items before they get to any water source-and there are a variety of inlet protection devices to do the job.
Keeping Adobe out of Adobe’s Stormwater
Adobe Systems recently constructed a LEED-certified, water- and energy-conserving, 280,000-square-foot campus near Lehi, UT. With so much earthmoving going on, erosion control was a top priority, and Lehi’s Silver Leaf SWPPP was on the job.
“This high-profile project is ongoing,” says Silver Leaf president Mike Christofferson. “The 38-acre master plan began in 2012; one section was finished in 2013, but then construction moved into a new phase last year. We’re doing all the SWPPPs [stormwater pollution prevention plans] onsite. For the initial phases, we installed silt fences, adding BMPs as the project progressed, mostly products from Gator Guard.”
Silver Leaf SWPPP has served the Utah and Colorado region for the past five years. “We install, maintain, and inspect all SWPPP items on site. We do hydroseeding and berming too,” he adds. “We also sometimes help with designs, the SWPPP for the project, or we can do it a la carte; it all depends on the client.”
Christofferson’s task on the Adobe project: Keeping soil onsite during initial construction. “The Adobe site is on a hill, so a lot of water is shed. During construction, there was lots of snowmelt, and in the early phases we had a lot of rain that year, which is unusual. That’s why we used silt fences as well as Gator Guard, which was used on the perimeter, to keep the clay soil sediment from street gutters. I like Gator Guard’s low profile, and the product is durable. Where silt fence stored along the fence line can get ripped up, Gator Guard is still intact after storage.
“Another great thing about Gator Guard-many BMPs are site-specific, meaning some work well on some sites but not on others. Gator Guard works almost anywhere, especially on large projects that stand for several years. It’s important for us to have a product that holds up, because we don’t want to do costly reinstalls.”
Shipped to the site in 25-foot lengths, the Gator Guard was lightweight and simple to install. “Our crews put it down by hand,” Christofferson continues. “One guy can do it easily, although we typically have two installers. The product comes with 6- to 8-inch nails, which are hammered into Gator Guard’s flap; that holds it down onto the soil. We also use rocks or dirt to hold the flap down, so no water can go over or underneath it. All stormwater inlets are in the street. For areas such as parking lots, we used different products to trap sediment; there was too much traffic to put Gator Guard there.”
Used only as a temporary item (i.e., it does not degrade and become part of the landscape), Gator Guard is removed when work in an area has been completed. The product is then moved to the next needed area. “We can reuse them, either on the current project or a future one,” he says. “On areas that have been finished with landscaping, Gator Guard has been removed, but it’s still down on about 10 acres. Some of the Adobe project is done; employees moved in during January 2013, but more expansion going on now. Our work on the project might last at least another year. My best guess? It might go longer.”
Raising the Bridge, Lowering the Sediment
It’s somehow ironic that many construction projects require purposely creating the perfect site for erosion. Case in point: highway overpasses and interchanges. Raising one area and lowering another instantly creates hills-water’s and gravity’s “best friends.” Along with proper drainage, installing erosion control BMPs at such sites is crucial. In Sacramento County, CA, an overpass and road-widening project at the Highway 50 and Watt Avenue interchange created challenges, and Team EES met them.
“The project started in November 2012,” reports Team EES project manager John Buhl. “I installed drain inlet covers before the prime contractor broke ground. I’ve since put in about 80 of them. The site contains a variety of drain types-curb and grate combinations, some were mere openings, some were for a culvert.” Buhl used products from ERTEC Environmental Systems of Alameda, CA, which produces Top Guard Inlet Protection Devices of several types: GR8 Guard, Combo Guard, Drop Guard, and Curb Inlet Guard.
Construction crews first scraped all vegetation off the site, exposing the soil. “We were subcontracted to put in temporary inlet protection, perimeter sediment control-using ERTEC S-Fence where the contract called for silt fence-and slope protection, for which we used ERTEC ProWattles instead of rice straw wattles. We also used ERTEC Hard Surface Guard for sediment control on the street, which is a difficult application, since most BMPs require trenching, which isn’t possible in paved areas. Hard Surface Guard is a great alternative to gravel-filled wattles; it’s much more lightweight, so installation rates are much faster. An employee can easily carry 140 feet of Hard Surface Guard at a time, compared to just 10 feet of gravel-filled wattles.”
“We primarily use ERTEC products for temporary sediment control,” he goes on. “Generic terms, such as “˜wattles’ or “˜silt fence’ or “˜drain inlet protection,’ are used in contracts. We use ERTEC whenever we can. We ask the project owner to substitute, and almost every time they approve. Instead of using straw wattles, we propose ProWattle. Instead of traditional silt fence, we propose S-Fence. These products install faster, require almost no maintenance, and they’re “˜zero-waste.’ When we finish our projects, we take the BMPs with us. No waste-we can reuse them. Since 3.5 thousand feet of ProWattle fits in a pickup bed, you can imagine the huge labor and logistical savings. That amount of straw wattles would require half a semi,” he explains.
“I basically installed all products myself-they require only one person-unless I needed someone to put out safety cones on the highway,” he says. “Most other types of inlet protection require a two-person installation, and quite a bit of time. With ERTEC products, gravel bags on each side hold Combo Guards and Curb Inlet Guards in place. Gr8 Guards are held in place with zip ties or tie wire. One of the key things about ERTEC’s Top Guard line is that we don’t have to remove the grate to install. This is a huge advantage for speed of installation, cleaning, inspections, and safety. It’s a big cost savings for us. And we don’t have to spend a lot of time to maintain. Grates are very heavy and can cause injuries-fingers, toes, backs. They’re often responsible for worker’s comp claims. These products install atop the grates.
“The drain inlet products are orange, which helps to keep street sweepers off them, which could damage them. The perimeter BMPs are all black material, as that color HDPE is more UV stable; we can expect those to last four to 10 years in the field. ERTEC assembles all its products with a filter inside, either green or black, depending on application.”
Installation is simple. “To install GR8 Guards, you need two holes, easily poked in with a Phillips screwdriver, for the zip tie in each corner. The installer can then insert a long zip tie through the GR8 Guard, down through the grate, feed it back up through the grate, and tie it off nice and tight above the unit. Each GR8 Guard needs four zip, or wire, ties. Along the highway, we initially installed them with zip ties only, but learned that units installed closest to the traffic lanes were blasted with bursts of air from passing tractor trailers. These constant bursts would cause the GR8 Guards to inch along the grate-those with bars running in the direction of traffic but no cross bars-and bow up. We found a simple solution. We secured them with sealant caulk, just on the edge facing traffic, to resist the wind. I personally sealed them all; it took a couple minutes for each unit. Since then, about a year ago, the GR8 Guard units have stayed in place nicely.”
Buhl explains that safety needs to be balanced with sediment control. “Drain inlet protection devices must allow some water to flow off the street into the underground pipelines for road safety. You can only stop 100% of the sediment by stopping the flow, which would be intolerable to municipalities and DOTs; road water is a hazard. It’s important to have flow bypass mechanisms around the filter. In my experience, ERTEC does this pretty well.”
When the project is finished, the Gr8 Guards will be removed. “Five or six have already been removed; the project may be completed at 2014’s end. Thus far, Combo Guards and Curb Inlet Guards have done well, with very little maintenance-all we’ve had to do is clear accumulated debris. We haven’t had to replace the filters, because most projects run much less than four years, which is the length of ERTEC’s warranty. When we clean a Gr8 Guard post-storm, the collected sediment and debris is relatively dry, making it easy to brush off, or shake it clean. If that section is finished, we remove the covers, then store or reuse them on the site. We only had to perform a full maintenance once last winter. For heavier-flow drains, we might have to clean grates a couple times.”
Cleaning up After the Tourists
With over 15 million visitors each year, Myrtle Beach, SC, is one of the country’s most popular beach resorts. While removing trash, floatables, and other pollutants is a crucial function of any stormwater collection system, water quality has a direct impact on the town’s economy; tourists want clean beachfronts.
Myrtle Beach’s stormwater collection system is extensive, with approximately 162 miles of drainage pipes and more than 55 beach outfalls with three deep-water outfalls, draining primarily to the Atlantic Ocean. Prohibiting floatables and trash from being discharged has a direct impact on the coastline’s beauty, as well as protecting public health and aquatic life. For more than a decade, Myrtle Beach has used more than 400 SNOUT advanced hooded outlet covers, from Best Management Products Inc., on the outlet pipes of key deep-sump stormwater inlets and distribution structures throughout the drainage network, both onshore and off. Monitoring has shown a 70% reduction of trash and other gross pollutants. It’s estimated that each SNOUT removes one ton of solids and debris annually, totaling a half million pounds of solids collected and removed from surface waters each year.
“This 2003 project was a retrofit of existing drains, and the first time I used Best Management Products,” explains Eric Sanford, P.E., CPSWQ, M. ASCE, a principal and director of municipal services for Myrtle Beach’s DDC Engineers Inc. “Now I use BMP products more every year, probably more than anyone else in the state.”
Myrtle Beach’s original drainage systems were installed in the 1950s by the state department of transportation. “But then, in the 1970s and 1980s, this area exploded in population, especially the seasonal visitors. In the last 10 years, the focus has been on drainage, so items have been upgraded. When we began this project, we were looking for something simple, effective, and, especially, cost effective. Another consideration: This area doesn’t have enough elevation difference to use some other methods that require gravity drainage.”
Crowds generate trash; the town’s biggest problems are plastic and cigarette butts. “We needed something to limit the number of them getting into the sea,” Sanford says. “Forty years into the Clean Water Act-sometimes water quality seems worse than it was then! I suppose it doesn’t help that recycling isn’t mandatory here. Beach sweepers are out every day to remove trash from the sand, but to further safeguard the waters, it was decided to source-treat stormwater. I became aware of BMP when I ran into its president, T.J. Mullen, at a Florida conference. I adopted the SNOUT program because I like it so much.”
SNOUTs are used throughout the system. “They’re used for source treatment in street drains; they fit very well into large drains-they’re adaptable and easy to install. There are two huge 96-inch ones in North Myrtle Beach, which has an outfall to the ocean. They work well there, because that area has only a 2-foot elevation difference (town to sea), where Myrtle Beach’s elevation is five feet. We also use other applications, such as Roscoe Moss flow screens, mostly in parking lots feeding to the stormwater system.”
Along with plastic and cigarette butts, SNOUTs are designed to contain oil, grease, sediment, and leaves. “We have yardwaste pickup here, so that helps keep some leaves from the stormwater. SNOUTs grab the rest. I’m not saying we have a 100% catch rate-there’s no great “˜magic bullet’ out there-but SNOUTs do a great job. They need to be cleaned out every few months, and the city uses vacuum trucks for that task.”
