By Chuck Gloman
Throughout the country, water quality continues to be a major issue. Each state and municipality might have different concerns, problems, and ways of eliminating those problems. The government is taking measures to protect the quality of water, and Phase II of the National Pollutant Discharge Elimination System (NPDES) takes effect in March. Phase I, issued in 1990, regulated cities with populations greater than 100,000; Phase II applies to municipalities with fewer people and municipal separate storm sewer systems in smaller areas.The key to water-quality protection, and the issue with which Phase II communities across the nation are grappling, is to identify nonpoint-source pollution problems and find ways of correcting them. Contaminants include silt and sediment from construction sites; oil, grease, and hydrocarbons from parking areas; litter in the form of bottles and cans; and pathogens from sanitary sewer overflows, agricultural operations, and other sources.Filtering Out PollutantsHow do you reduce the amount of nonpoint-source pollutants from reaching water supplies? A common way is to use a filtration system. Various types of mechanisms prevent debris from entering storm sewer inlets or catch basins and ultimately reaching surface-water supplies. Catch basin inserts, which fit inside catch basin openings and screen out the contaminants, and inlet protection devices, which fit over or around inlets, are commonly used. Several types of underground separation units – self-operating, gravity-driven, and with no moving parts – are also available.We looked at several parts of the country, noting specific concerns and pollutant removal strategies in different areas. From the numerous filtration products on the market, how do you choose the best device for your particular need? Each of the individuals interviewed chose a particular product on recommendations from others, trial and error, funding limitations, or past performance.The West Beth Smiley from Thunder Mountain Enterprises in California had a need to remove silt and sediment in new construction and commercial-type applications. She commonly uses SiltSacks (manufactured by ACF Environmental in Richmond, VA) in combination with other devices whenever possible. She considers them to be “our last line of defense.”“We use it with other erosion and sediment control measures to try to stabilize the soil particles whenever possible,” Smiley explains. By using other sediment control measures, such as straw wattles and rock bags in the gutters, she hopes to slow the velocity of flow and drop most of the sediment before it enters the drain inlet and reaches the SiltSacks.In California, stormwater pollution prevention plans (SWPPPs), required under NPDES general permits, must be in place for any new construction greater than 5 ac. until March 2003, when it becomes greater than 1 ac. (coinciding with NPDES Phase II).Smiley monitors and maintains her systems once a week, rain or shine. “When it’s raining, you are required to maintain them more often. We do our documentation and check our drain inlet sacks once a week. We actually check the whole site because it’s an overall site inspection, and the drain inlet protection is included in that. We provide the documentation for our developers and put it in their folders or binders that are on-site.” The monitoring system doesn’t have to be complex, but consistency is the key. Smiley states, “We are constantly tweaking our sites every week, especially during our wet season, which is May to October. We have a 303(d) list, which is a list of sediment-impaired water bodies in California, ours being Area Five [Sacramento]. We have only three sediment-impaired water bodies on that list. If your site discharges directly into one of those, you are required to test four times a month. But since we have only three in this area, most of our sites are not dumping directly into those water bodies. When the list is updated, we may have more water bodies in our region designated, and we’ll have to do more.”Smiley is pleased with her inlet protection device because, she notes, “it has been engineered and tested to function with different flow rates from 40 to 200 gpm. I like it because it’s got a gasket effect; it sits on the outside and into the grate. It’s the best one we’ve been able to find.”Sacramento County’s extensive SWPPP has been implemented because of the problems associated with first flush. With the rainy season being October 1 through April 30, the very dry summer accentuates Sacramento’s Mediterranean-type climate. “The first flush is extremely important because of all the pollutants on the land, roadways, and our lawns – the water quality has to be monitored constantly,” explains Janet Perris, principal engineering technician for Sacramento County’s stormwater program. “Erosion control is always the first line of defense, and inlet protection, especially with our construction sites, is the last line – it’s just keeping safety in mind.” Suzanne Patton, a civil engineer with AC Transit – the third-largest public bus system in California, serving Alameda and Contra Costa Counties – is pleased with the performance of the Flo-Gard catch basin inserts installed and maintained by KriStar Enterprises at some AC Transit facilities. “Bus parking lots are a major concern,” she notes. “Pollutants collect on the pavement and run into the storm drains.”Flo-Gard contains an absorbent called Fossil Rock (an amorphous alumina silicate) that removes petroleum-based pollutants (hydrocarbons) such as oil, gas, and lubricants. “These same catch basin inserts remove not only petroleum hydrocarbons but litter, debris, vegetation, sediment, floatables, and other waterborne pollutants,” maintains Jim Ford of KriStar.Because the filters fit under the inlet grate of a storm drain system, they are easy to install, maintain, and monitor. “The advantage of being placed at the inlet of a system is that they remove pollutants before they have a chance to become emulsified. Other pollutants – paper, vegetation, grass clippings, and leaves – are removed before they have a chance to become fully immersed in the water, dissolve, and decay into harmful nutrients as well as, through decomposition, generating gases and offensive odors,” says Ford.
The harbor in Dana Point in southern California is under revitalization, and a number of KriStar’s Fossil Filters have been installed. John Garofalo, a park maintenance supervisor with the City of Dana Point, believes “You get what you pay for” and had to fight to get the right type of filter.
The Dandy Pop pops up, and grates slide right in. For creek diversion and urban runoff in an area across from a major highway and residential development, Garofalo explains, “We berm it with sand and monitor the flow into the creek. I pump it with a 6-inch trash pump every other week into the sewer system, which goes to the plant for treatment. At the west end of the harbor we have an 18-inch and 21-inch storm drain. The bluff above Dana Point Harbor drains down into a spider-web maze of storm drains to one of those two mains. I insert bladder bags and inflate them in the warm season and do the same with the 6-inch trash pump at the west end of the harbor.” Garofalo has been using bladder bags and the sand berm for the past three years and the catch basin inlet filters for almost two years.With California’s history of sparse rainfall amounts, first flush is a problem – mostly from urban runoff. “I was in direct contact with the City of Dana Point because we are the county and the county owns and maintains the harbor. The city was a couple of steps ahead of us in the filtration system department and told us what not to use. They recommended Fossil Filter because it bolts to the inside of the inlet, and so far it has worked out great for both of us,” Garofalo remarks.One of the biggest problems affecting the waterway at Dana Point is bird fecal matter. Tom Rosmiller, an engineer, works directly with the local health care agency in addressing this concern. With a water-quality test performed every three days, Dana Point has put a net underneath the pier to stop pigeons from nesting there in an effort to control the waste entering the water. Filtering can accomplish only so much; the real need is to remove the birds.The East
The Snake Bag gravel wattle can be used over and over.
The Orange Gravel Bag is used where visibility and burst strength are needed.
Straw or coconut wattles filter and slow water flows into culverts.Sometimes your specific need requires a product that isn’t readily manufactured. Mark Converse, sales manager of Site Supply in Columbus, OH, needed a filtration device that didn’t exist before his call to sediment control device manufacturer Dandy Products. “We were providing the widely used Beaver Dam and Dandy Bag products to site contractors in Ohio but found they were looking for a much different product – one that could be easily seen by construction traffic and would be easy to clean and maintain. That was the origin of the orange pup tent-like structure that eventually would become the Dandy Pop. It just pops up and the grates slide into it.”Common field practice was to erect a silt fence structure with wire mesh and 2x4s. Building the structure was a time-consuming process, and the results seemed less than ideal. Silt and debris would find ways over and under the fence; thus a better solution was needed.Converse spent time getting feedback from government agencies, contractors, and experts in the erosion and sediment control field. “The suggestions were helpful, and with the manufacturing and design expertise of Dandy Products, a really innovative product emerged, a product contractors and environmental regulars seemed to really like.” The Dandy Pop became a collaborative addition to the growing line of products that help reduce silt and sediment.With space being an issue, early prevention programs involved using wire mesh, gravel, and 2x4s to keep debris from entering the water supplies. With winter snows, these devices had to be visible, but plows would often destroy the more fragile wooden structures. Dandy Bags solved this problem because they lie flat and are difficult to tear up, even with snowplows.Residential and business applications and the many different available products are all merging to reduce silt and sediment in streams. Erosion control blankets, geotextile fabrics, pond liners, and silt fence all are used in the Columbus area. Combining products and getting contractors and owners simply to seed potential erosion areas can reduce silt and sediment pollution to a great extent.Silt and sediment are a major concern in a mature and urbanized state such as Ohio, Converse observes. “You may have streams running clear for years, and all of a sudden you get construction upstream and everybody notices it right away. There are just so many people watching our local waterways.” With Ohio’s evenly distributed 36-40 in. of rain each year, inlet protection devices will continue to see use year-round. While logic should say that these products would be the last line of defense in the battle against sediment, field observations have shown otherwise – they might be the only line of defense. The SouthThe City of Temple Terrace, FL, purchased land and created a 2-ac. pond with wetland plains (a manmade marsh) to help filter polluted runoff. The city also purchased underground continuous deflective separation water pollution control devices, manufactured by CDS Technologies, which have shown success in other parts of Florida. The South Florida Water Management District helped fund installation of the units. “We don’t always have the luxury to do this with every project,” acknowledges Joseph J. Motta, Temple Terrace city engineer. “We can’t always construct a pond. In those cases we will treat the water and then discharge it back into the river.”
As water is diverted from drainage pipes to the CDS units, it moves in a circular motion, passing through a perforated screen; pollutants and debris end up at the center of the cylindrical unit and most settle into the sump. The sump is monitored, and solids such as leaves, trash, and sand are removed. “When the water comes out of there, it’s pretty clean,” Motta points out. “There’s also a screen, so no solids, especially silt and sediment, can get out once the water goes through the sump area. Only very fine particles may get through, and they go directly into the marsh area, so we get even more settlement before it goes out to the river.”Maintenance is required for any system to function properly. The sump area in the sanitary sewer is cleaned with a vacuum truck. Large-diameter pipes are used to remove trash of all sizes. The trash is collected in a truck, dumped in one of the county’s yards, and disposed of properly.The wet season in Florida differs from that in California, lasting only from June through November. This means more frequent cleanings in order to keep the system functioning properly. During the drier summer months the cleaning and maintenance schedule is less frequent. The summer has another negative side in that a lot more pollutants are traveling through the system. With sometimes a month or two passing with no rain at all, people want to water their lawns and wash vehicles, and this dry-weather flow can be tougher on pollutant removal systems; restrictions must be implemented during these drought conditions.Summer is also the most likely time for the first-flush effect in Florida. Water is tested as it enters and exits the system. Mini laboratories in trailers are set up on-site to take samples and perform these necessary tests.The systems in Florida must be massive to handle the large diameter of the stormwater pipes. The 8- to 10-ft. concrete structures are installed 23-25 ft. in the ground. “With smaller projects, wherever we have a 50-foot area, we can fit the whole unit comfortably with an easement or right of way,” states Motta.
Motta also notes that the Water Management District had experienced success with the large CDS units in other cities and encouraged Temple Terrace to use them. “We’ve got this big pipe, and I believe we are trading close to 40 cubic feet per second, and that’s quite a bit of flow. Some of the other products can’t handle flows of that magnitude. The [district] had experience with the [CDS] system and is happy with it.”
Guest author Chuck Gloman is a writer and producer in Pennsylvania.
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Andrea Weissenbuehler
