July 19, 2010 05:16

Storm Drain Inlet Protection

UP UNTIL A FEW DECADES AGO, protecting our waterways from contaminates wasn’t a big deal. Rain fell from the sky and was naturally absorbed into the soil, and wild or native plants held back erosion. In most parts of the country, there was plenty of earth and vegetation to handle most rain events, and when there was an occasional downpour, the stormwater flowed cleanly into drains and harmlessly out into the rivers and oceans.

But once we began to “pave paradise to put up a parking lot,” the number of impervious surfaces began to increase. Construction of new homes, especially hillside developments, destroyed much of nature’s filtration system. Stormwater runoff still flows into storm drains, but now it also takes along with it oils, sediments and other toxins, which have begun to pollute our once-clean waterways.

Reducing contaminant entrance into storm drains is critical for a healthy eco-system. Contaminants such as debris, organic solids, trash, soil particulates and organic liquids significantly impact downstream ecologies. Often, unseen nutrients, pesticides, herbicides and detrimental chemicals are attached to the observable items. Once in the drains, many of these items degrade into ‘brews’ and ‘residues,’ which further impact receiving water bodies.

To help solve the problem, the Environmental Protection Agency (EPA) enacted the Federal Water Pollution Control Act (also referred to as the Clean Water Act). Soon after, the act was amended to include sediment control regulations. These regulations, called the National Pollutant Discharge Elimination System (NPDES), were designed specifically to reduce stormwater pollutants from new development and redevelopment construction sites.

One of the basic components of the NPDES is in the area of storm drain inlet protection (SDIP). Inlet drain protection is a secondary best management practice (BMP), which is used along with other erosion control methods to reduce erosion and prevent debris and associated pollutants from entering stormwater underground pipe systems.

Storm drain inlets provide easy-to-maintain locations for contaminant collection. However, the effectiveness, maintenance costs and potential failure of collection devices are directly related to the design of the device.

Temporary protection products are used before and during a construction project and are usually removed once the construction is completed. Industry standards, including sandbags, silt fences, straw wattles and others, have been very effective in blocking pollutants around storm drains when rain events occur. Different types of inlet protection are used, depending on the amount of the water flow, site conditions and the type of inlets that need to be protected.

Although the design and materials to accomplish this vary from one manufacturer to another, they all share a common goal: to filter sediment and pollutants and trap them before they have a chance to flow into the sewers. While the end goal may be the same, the means to that end are changing, especially with more and more emphasis on environmental concerns. Manufacturers of SDIP devices are becoming more attentive to the needs of not only their clients, but to the planet as well.

“Our company manufactures inlet protection and perimeter controls products that are composed of rubber from recycled tires,” say Bruce Sandau and Jim Daulton, owners of EcoGuard, Platteville, Colorado. “Recycled rubber is a whole different animal in SDIP. Our old product standard was to use perforated pipe with gravel. We found that rubber is better because it has the ability to hold 30 percent more water than gravel does.”

While not environmental fanatics, Sandau and Daulton strive to make the world a better place. “We want the earth to keep spinning, the sky to stay blue, and our waters to remain clean,” says Daulton. “We work with another company that is in the business of recycling tires. The process they use strips all the metal out of the material, so there are no foreign particles in our bags. And because they’re rubber, they hold up to heavier types of traffic and construction equipment.”

Dan Cleveland, president of Dandy Products, Westerville, Ohio, has been manufacturing SDIP devices since 1995 and has definitely seen an improvement in environmental sensitivity. Not only because of the EPA regulations, but also because the general public is more aware of the importance of keeping pollution out of their lives.

“With so much more knowledge about carbon footprint, people are more aware and concerned about the environment. Even without the EPA’s stricter regulations, we see our clients taking better care of stormwater runoff and inlet drain protection because they understand how important it is to our environment,” Cleveland says.

Dandy Products are composed of a monofilament geotextile material that can be used above or below grates, depending on the job requirement. The company manufactures bags, sacks and pop-tents that are used above-ground. Suspended solids settle out of the stormwater flow and are captured by the bag prior to entering the drain inlet.

Under-grate hinged filter protection devices are a viable alternative to above-ground SDIPs. “The hinge design allows the filter to fold in the center, making it easier to remove when filled with sediment,” says Rich Quinley of World Textile and Bag, Roseville, California. “Because this is a belowground filter, no filter fabric extends above the grate, so it doesn’t tear easily. It can be installed, cleaned and removed by one person.”

New on the SDIP scene is Dana Hendry, owner and vice president of Inlet Protection Company, LLC, Gonzales, Texas, who has been manufacturing and installing SDIP devices since January 2009. “Our ‘Curb Companion’ devices fit inside the throat of the inlet and are not visible from above; therefore, there are no protruding parts to be a traffic or pedestrian hazard. These devices are easily maintained with the use of street sweepers or a broom and shovel,” Hendry says.

While these protection devices are for temporary use during construction, permanent belowground devices are used where site activity involving organic pollutants is ongoing, such as parking lots and industry maintenance areas.

Catch basins, also known as storm drain inlets and curb inlets, are installed under the grate at these locations. Filter inserts designed to remove oil and grease, trash, debris, and sediment can improve the efficiency of catch basins. Some inserts are designed to drop directly into existing catch basins, while others may require retrofit construction.

“Inlet filters capture more than just the stuff that would wind up at the bottom of the catch basin,” says Carol Happel, director of information technology with Suntree Technologies, Inc., Cocoa, Florida. “The Grate Inlet Skimmer Boxes contain an absorbent sock that captures oils and free-floating hydrocarbons which would otherwise wash downstream. Once the sock is saturated with oils, the service crews just pull them out and replace them.”

Inlet filters are designed to dry out captured foliage so that it stays dry between rain events. That way, you don’t have standing water—a mosquito or bacteria habitat—in the drain. The debris is sucked into a vacuum truck, and the filters are cleaned regularly by maintenance crews.

Happel says that certain states, like Florida and California, are very progressive in requiring cities to comply with stormwater regulations, with more and more coming along about every month. “We’re seeing a lot of retrofits in these areas,” she says. “Municipalities are finding out that they don’t have to redesign the entire watershed. Early on, people were worried that the filters were going to

The CatchAll HRI filter system catch all the sediment and the streets would back up, but it’s just the opposite. Now we’re able to protect the drains and, with regular service, not only won’t they back up, but they’ll keep the stormwater clean.”

With more people becoming environmentally conscious, Happel says that when crews are installing stormwater treatment devices on a residential street, homeowners are very enthusiastic because they realize that it’s going to keep their waterways clean. “Especially if they live near a lake or pond where they’re accustomed to seeing a lot of trash floating on the surface, they’re more than happy to see a device that will capture all that junk before it goes into the lake,” she said.

“We’re definitely finding a lot more awareness of the environment with our clients, especially when they realize that inlet drain protection isn’t only for temporary use during construction, but something that’s necessary all year long,” says Greg Piper, vice president, Marathon Materials, Plainfield, Illinois. “It’s not only how the filters work, but the materials that they’re constructed of that is all part of the new eco-friendly world.”

Like the skimmer boxes, Marathon Materials’ CatchAll HR-I filter system is permanently installed in open-grate frames to prohibit silt, debris, and organic liquids from entering stormwater systems at inlets and catch basins. The system is specifically engineered to absorb a wide range of organic chemicals, including gasoline, diesel fuel and motor oil.

John Price, president of Price and Company, Inc., Wyoming, Michigan, offers both of these systems to his customers. “The CatchAll series is used in areas where organic liquid contaminants are a primary concern.

Grate inlet skimmer boxes are used in areas of moderate-to-high particulate movement or where maintenance intervals are lengthy.”

The EPA has proposed six separate questionnaires focusing on gathering data about current stormwater management practices from specific groups. These are designed to strengthen stormwater regulations and to establish a program to reduce stormwater from newly developed and redeveloped sites. The EPA is intending to propose new rules to control stormwater and to take final action no later than November 2012. With this in mind, there is little doubt that the industry will be looking towards more efficient, lighter, and ecofriendly devices that will meet and exceed the new regulations.

New technologies, such as upflow filters, are coming onboard in the not-so-distant future. According to

Price, people want to get rid of heavy metals, phosphates and nitrogen—the nutrients from fertilizers, in particulate form. “We can get rid of these through simple filtration,” said Price. “When they become dissolved, they’re much more of a problem. Typically, you have to use some form of a filter mechanism. In low-flow conditions, it’s pretty easy to get those things out of the water by having them flow upward. In another two to three years, they’ll be used as a final filter.”

It took years of ingenuity for man to create the wonderful living environment we enjoy today. By protecting our inlet drain systems and keeping our waterways clean, we’ll be able to enjoy them for many years to come.

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