Preparation can be the contractor’s key to success. Like a great athlete during a warm-up, taking steps to prepare for problems that can happen-before they do-means finding solutions for your project’s erosion problems once, not several times.
Keeping sediment and runoff on your project site contained involves choosing products that work with your site’s environment and within your project’s budget. No one product can serve every site, but determine which best management practices (BMPs) are best suited to your site’s runoff conditions and you’ll have a winning combination.
Reusing Sediment Control Materials
Distance posed a challenge for one utility site. Lucinda Dustin, owner of Mud Hen Environmental based in Sacramento, CA, describes an ongoing Fresno, CA, project where power poles were replaced over several miles.
“Some of it is through grazing ground for cattle-it’s ranchland. There are a lot of orchards. Almost all the overland projects are like that. I haven’t worked on a linear project yet that doesn’t go through private property,” she says. “We try to use products that are the least invasive.”
At this site, Dustin says, workers have a 300- by 100-foot area guard that has to be protected as they move the power poles. She selected ERTEC Environmental System’s Perimeter Guard, which can be installed quickly and then be lifted up and moved to the next work area.
“We use it in place of straw wattles and silt fence,” says Dustin. “You have to be careful where animals are. Cattle like to tear open the straw wattles and eat the straw.”
Dustin says the Perimeter Guard can handle trucks rolling over it, and it doesn’t need to be trenched. Its ease of instillation eliminates the need for hiring additional contractors. “It’s not cost-effective for a power company project to have an outside contractor come in if it’s a very active site,” she notes.
Fiber rolls, which Dustin also still uses, are more work to install and are heavier than Perimeter Guard. “Although the up-front cost is higher than a fiber roll,” she says of Perimeter Guard, “they are reusable. My goal is to use as much material that is reusable and good for the environment.”
Controlling a Fire’s Muddy Aftermath
An environmentally friendly solution for an environmentally damaged site was important for one fire-ravaged California community. Sediment control has become a huge issue in southern California following the October 2007 wildfires. Homeowners in a residential community in San Diego were required to take action to trap the scorched topsoil and slow the runoff in a free open-space zone on the 12-acre site before it entered several backyards.
“The homeowners were responsible for maintenance and upkeep; they are responsible for the rehab,” says Andrew McGann of Earth Saver Environmental Control Products. The homeowners chose straw wattles from the company, which is based in Woodland, CA. “We went in there and installed about 8,000 lineal feet of the straw wattle along the control.”
The homeowners were looking for a green solution. “They were looking for something that they could leave in place that would breakdown over time,” explains McGann. “The fiber content is 100% noxious-weed-free California rice straw. The netting is a photodegradable netting.”
Even though residents had to remove some of the sediment that was trapped behind the wattles, says McGann, the product worked well on the site, keeping the sediment out of the storm drains and backyards.
Lining Protection“We needed a way improve the drainage and the maintainability for the swale,” says Neil Bartlett, public works director for Goldsboro, NC, of work done on a recent site. Lining shallow swales is an option, and Goldsboro used SmartDitch, a high-density polyethylene (HDPE) lining system made by Penda Corporation, based in Portage, WI.
“We decided to try it. The swale was not really deep enough to get any size of concrete pipe in,” explains Bartlett. “This was done last August. So far, we have been pleased with the results.”
The swale is adjacent to a residential development. Concrete lining was cost-prohibitive, he says. “It would have created an unsightly hump.”
Had a conventional reinforced concrete pipe been used, the site might not drain properly. The area was in the midst of a severe drought, although typical weather for the area includes heavy thunderstorms with some regularity.
Transportation Challenges
Transportation sites frequently need to make short-term provisions for sediment and runoff control. The Transportational Regional Expansion Project, tackled by the Colorado Department of Transportation (CDOT), was no different.
The project is “11 miles of road lane widening through the heart of south Denver,” explains Ken Kinnard of Bowman Construction Supply, based in Denver. Over the course of four years, workers installed about 300 Dandy inlet protection products, he says, including the Dandy Curb Bag, a monofiliment geotextile filtration bag used to capture suspended solids at curbs and inlets; the Dandy Bag, which, like the curb bag, allows suspended solids to filter out of slowed flow before entering an inlet; the Dandy Sack, an open-top bag that is placed under a storm grate to filter suspended solids out of a slowed flow; and Dandy Dewatering Bags, constructed from a Mirafi geotextile.
“They were evaluated by CDOT. They chose them as the preferred drain inlet protection product,” says Kinnard, who noted that during the course of construction the products handled dozens of major storm events. “We can have a 2-inch downpour in 30 minutes. The Dandy products protected the site marvelously.”
Improving Water Clarity
Rain for Rent, a Bakersfield, CA-based company that provides consulting, installation, and operation of stormwater equipment, works on about 30 job sites in Washington state each year. Sediment and runoff control is a common problem there because of the climate. At one site, a commercial big box store near Tacoma, the customer had an unusual way of handling water after a large number of rain events.
Steve Wait, a regional filtration specialist with Rain for Rent in the Rocky Mountains and Pacific Northwest, says the client had dug ponds to control runoff, then allowed water in the ponds to infiltrate into the ground. Unfortunately, the water table was so high that the ponds would overflow before they had a chance to drain.
“They called Rain for Rent to filter the water to meet 10 NTUs [nephelometric turbidity units]. The major component of turbidity was in between half a micron and three microns. Functionally, you can’t really filter that with traditional filtration,” says Wait. The company set up a StormKlear system to deal with the fine particles and improve filtration.
Water in the ponds had a turbidity level of about 2,000 NTUs before treatment. “[The system] dropped off a majority of the sediment into tanks, then the clear water was pumped through a sand filter to bring [the turbidity level] down. Out of the tanks it was about 70 to 80 NTUs,” he says. “Through the sand filter, it was less than one NTU.” Although the requirement was for discharge to have 10 NTUs or less, “we were typically below one,” he notes.
Wait says the 12-acre site posed a challenge that couldn’t be achieved without using chemicals. “It really saved the day,” he says of the StormKlear system. “The chemical is the magic bullet.”
Protecting the Skykomish River was also a top priority for a large remediation construction site adjacent to the body of water in Skykomish, WA. “We had full-time [Washington State] Department of Ecology staff monitoring performance,” says Jim Mothersbaugh, president of Water Tectonics based in Everett, WA. “We were operating 24 hours a day, 7 days a week for 103 days at a flow rate of about 1,200 gallons a minute. We successfully discharged into the Skykomish River at less than 10 NTUs, and 90% of the time, less than 5 NTUs.”
The project, which began in March 2007 and continued until early September 2007, used a chitosan system to remove turbidity and sediment from runoff.
“StormKlear, a chitosan product by HaloSource, works exceedingly well when the water has a low or high conductivity, the average influent turbidity is under 600, and the pH is less than 7.5,” says Mothersbaugh. “We also encountered emulsified oils and TPH. We then incorporated carbon filters, four of them at the end of this process.”
Water Tectonics used StormKlear on a separate site, the Gog-Le-Hi-Ti landfill in Tacoma, WA, beginning last summer. The landfill was being excavated, and the company worked there for six months during the process.
“We were set up to operate again at 1,000 gallons per minute, even though most of the treatment occurred at less than 600,” says Mothersbaugh. “We utilized pretreatment of sodium hydroxide to remove dissolved metals, then we adjusted the pH back to an acidic condition to reduce the turbidity.”Rebuilding HomeHouston, TX, frequently experiences major rain events, which can pose a challenge when soil is disturbed as it is on construction sites. One ongoing project, which began two years ago, is the ConocoPhillips headquarters where the main campus is being rebuilt in phases.
“In these construction areas there is loose dirt everywhere,” says John Moss, director of project management at Construction EcoServices based in Houston, which worked onsite. “Under the TPDES [Texas Pollutant Discharge Elimination System] permit, you’re required to not allow silt, sediment, or other pollutants to enter the storm drain.”
The site’s runoff flow feeds into the Galveston Bay. “There were a large number of inlets on the site, in excess of 40,” he says. Each inlet was protected with one of various types and sizes of ACF Environmental’s SiltSacks. The geotextile sacks are placed beneath the inlet grates. The devices had to withstand the site’s heavy traffic while protecting the inlets, says Moss, explaining that there was a large amount of debris silt and sediment. “It required a very durable product.”
EcoServices selected the standard-flow-rate SiltSack for use at the site. “We need to trap a variety of soil types. On some sites, we have soils that are finer,” says Moss. “You want to get as much flow as you can while still trapping the silt and sediment from entering the storm drain.”
The product was frequently inspected, along with the 300 other sites managed by Construction EcoServices in the Houston area.
“We have inspectors that see each one of these sites every seven days. We write the SWPPP [stormwater pollution prevention plan] narrative,” says Moss. “We install any BMPs required for compliance, then file inspection reports and update the SWPPP plan at the site.”
Turning to Geotextiles
At a real estate development in Lincoln, NE, Containment Contracting Services used triangular silt bags to combat runoff and control sediment.
“There had been a number of significant rain events prior to that instillation, and the sediment loss was so great on that project that gullies were created 6-feet-wide by 6-feet-deep. The streets had to be completely regraded after that,” says Brock Peters, president of Containment Contracting Services and a member of the IECA board of directors. He notes that the project site already had sediment basins that were virtually full.
At a second site, also a real estate development in Lincoln, Peters used CCS-designed inlet protector.
“The structure of it is different, as well as how it’s anchored in the ground,” he says, describing the design as about 95% maintenance-free.
Fabric anchors the device into the ground. “It is merely trenched in the ground around the concrete box, and many times it’s actually rock fill that holds it in place,” says Peters. “Whenever [crews] are finished with it, they can pull the fabric off of it and reuse the frame. Most frames like that are staked into the ground. In the process, they end up being destroyed upon removal.” The device is made of 2 x 4 wood with poultry netting on the outside for support.
Long-Term Golf Course Protection
Golf course construction frequently requires a strong system of BMPs for sediment and runoff control. This was the case for the Aetna Springs Golf Course in Pope Valley, CA. The course was adjacent to an unnamed stream that needed to be protected during the course’s construction, which began in spring 2007, according to Demae Rubins, a project manager at Summit Engineering based in Santa Rosa, CA. She used ERTEC’s Perimeter Guard and ProWattle onsite, both of which handled several major rain events. Water can flow through the products, which are made of recyclable HDPE, but the flow velocity is slowed and fine particles are filtered from the runoff. The Perimeter Guard is still in use as part of the long-term stormwater management plan at the site.
“It’s a product that’s easy to maintain,” says Rubins. “At times when you see the sediment traps filling up, you hose it down and then reinstall it. The reuse is a big key. With wattles, there’s a maximum capacity they can absorb. The golf course staff regularly monitors the Perimeter Guard.”
ERTEC’s Perimeter Guard was also used during construction at the Dominican College Campus in San Rafael. The device was employed for 16 months in an effort to protect Sisters Creek, which stretched out adjacent to the site.
“The site was surrounded by sensitive areas, both in terms of the creek, and the built-out campus that could not allow construction runoff hampering its use. This provided a solution that required little maintenance, was flexible to our needs, and was very reliable,” says Jeff Robertson, senior project manager at Cahill Contractors based in San Francisco. “We began with straw wattles and for a period used both systems, but ultimately favored the Perimeter Guard only.”
The company was able to reuse the device during the second wet season at the site. “We used it at the perimeter, as well as to establish intermediate barriers to slow the flow of water on the graded swales,” says Robertson.
Battling High Velocity
When you’re battling the currents of a river for sediment control, it’s important to have some tough weapons in your arsenal. When the Faust Corporation, based in Grosse Pointe, MI, was contracted to dredge the BASF Riverview site on the Detroit River for heavy metals, it installed Brockton Equipment’s Siltdam.This turbidity barrier floats by using a series of polyethylene logs, which are enclosed in a heat-sealed, vinyl woven-polypropylene fabric that allows water to flow through while trapping sediment.
Work at the site, where an old landfill is located, required an impermeable barrier to a depth of approximately 20 to 35 feet, according to Marc Faust, owner of Faust Corporation. The barrier had to hold up against the river’s high flow velocities.
The company “established a diversion wall at the upstream end to divert the current around the work area,” says Faust. Other factors needed to be addressed downstream as well.
“Immediately downstream, you’re going to have a turbidity effect. We needed an impervious curtain with no flow through.”
The Siltdam stretched from the top of the water to the river bottom and remained in place for six months during work at the site, which began in 2006.
“We had to go to some extraordinary measures to anchor the curtain in place. Once that was accomplished, we were totally successful. We were doing continual, real-time turbidity monitoring,” says Faust. “Never, during the whole entire project, did we exceed the action levels. We never even came close. The curtain was totally successful.”
The company considered using two other products at the site, but Faust says three facets of the Siltdam made it the ultimate choice: “There was availability. There was cost. But also there was certain backup information and way the company reacted with giving us support,” says Faust.
Slopes and Silt Fencing
At a residential site in Springboro, OH, 4% to 6% slopes posed a challenge for workers trying to control sediment and runoff.
“You have more sediment when you have more slopes,” says Greg Vreeland, CPESC, president of Erosion Runner based in Dayton, OH. The slopes are located upstream from silt fence the company had installed. Volume was one reason the company’s silt fence was used on the project.
“Silt fence has the advantage that it can trap more water, just by virtue of being higher,” he says. “If you don’t have storage capacity behind it, it’s not going to be effective.The reason silt fence is effective is it can oftentimes trap a larger volume of water than some other devices. Let’s say it’s reasonable to trap 12-inch high water [that] goes back 30 feet behind the silt fence. If we compare that to a wattle, it might only trap water 6 inches high and 15 feet behind the wattle. The volume of the water that is getting treated is about four times as much.
“So, often with silt fence the inferior products are sold and the people who are buying them don’t know the difference. Likewise, the inspectors will go on a site and say, “˜Well, it failed. The specifications need to be tighter.’ But before they say the specifications need to be tighter, they need to determine if what was actually used met the specifications that were required,” says Vreeland. “Many people use inferior materials and don’t really understand what they are supposed to be using.”
The company’s silt fence is made from black polypropylene that meets the Ohio Department of Transportation and Department of Natural Resources’ standards. The material is installed using 2 x 2 hardwood stakes.
“We use the right materials and we actually do a good job installing them,” says Vreeland.
And when it comes to any form of sediment or runoff control product, these decisions make the difference between defeat and a job well done.
