Two small MS4 communities take innovative approaches to controlling sediment
The U.S. EPA lists sediment as the most common pollutant in rivers, streams, lakes and reservoirs. Sediment pollution causes $16 billion in environmental damage annually. While natural erosion produces nearly 30% of the total sediment in the U.S., accelerated erosion from human use of land accounts for the remaining 70%.
Sediment entering storm water degrades the quality of water for drinking, wildlife and the land surrounding streams. It also clogs storm drains and catch basins that carry water away from roads and homes, which increases the potential for flooding. All cities, counties or other government entities are required to have a Municipal Separate Storm Sewer System (MS4) permit that authorizes the discharge of storm water collected by their storm sewer systems into water bodies in the U.S. Effective January of 2017, the EPA Final MS4 General Permit Remand Rule requires “clear, specific and measurable permitting” conditions for measuring best management practice (BMP) implementation.
In addition, MS4s that discharge to impaired waters must develop a total maximum discharge limit (TMDL) strategy and plan to reduce sediment, phosphorus and nitrogen discharged into protected watersheds. Storm water managers for smaller MS4s are finding innovative ways to purchase equipment that helps them meet BMP permit requirements for sediment and pollution control.
Reducing Sediment in the Ohio River
Situated along the Muskingum and Ohio Rivers, the city of Marietta, Ohio, with a population of 20,000, is focusing on reducing the sediment and debris that enter its waterways. According to Stormwater Manager Kathy Davis, a crucial part of those efforts is the city’s street sweeping program. Since 2003, the city has been required to administer a storm water management plan with the Ohio EPA. The plan helps reduce sediment, phosphorus and other pollutants from entering the rivers.
Sweeping takes place on 85 miles of streets. With hundreds of catch basins connected to the surface transportation network, the city must also clean them on a regular basis. To maximize the use of taxpayer dollars, the city purchased a multi-purpose street sweeper with a catch basin cleaning capability, removing 200 tons a year with a single machine.
The Marietta Streets Department has divided the city into five sections for street sweeping and catch basin cleaning, according to Streets Superintendent Todd Stockel.
In May, with summer weather in sight, Marietta launched its five-day street sweeping schedule, which covers one section per day Monday through Thursday and ends with overnight sweeping of the business district Thursday night and into Friday morning. The schedule stays consistent throughout the summer, allowing residents to plan ahead and move their cars.
Catch Basin Cleaning
The city uses an A7 Tornado regenerative air street sweeper from Schwarze Ind., which also has a catch basin hose attachment. According to Stockel, the biggest challenge the city faces when it comes to its catch basins is leaves. Although Marietta offers leaf pickup over a six-week period in the late fall and educates the public on placing the leaves between the curb and sidewalk so they stay out of the streets, some of the leaves — along with some salt and sand from the city’s snow removal efforts — make it into the storm drains.
The city of Marietta has a sewer vac truck, but the streets department has found the street sweeper to be its preferred equipment for catch basin cleaning. One of the primary reasons is size. The sewer vac truck is “problematic to get into the tight corners throughout the city of Marietta,” Stockel said. “All our streets are accessible to the street sweeper.”
Stockel noted that the A7 Tornado’s spray wand attachment helps drastically with the cleaning efforts.
The use of the street sweeper for both sweeping and catch basin cleaning helps keep sediment and debris out of local waterways, helping the city meet EPA guidelines.
“It’s relied upon very heavily in our schedule and maintenance program in addition to what it does throughout the summer months on its scheduled street sweeping, so it’s vital,” Stockel said.
Small Cities & County Team Up
In Washington state, the Department of Ecology regulates the state MS4 permits and also administers grants to local municipalities. The cities of Asotin (population 1,300), Clarkston (population 7,400) and Asotin County (total population 20,000) agreed to work together and developed an interlocal agreement to manage the work required to meet permit requirements and manage matching funds provided by ecology through the legislature to assist in the development of the storm water management plan (SWMP).
The development included a gap analysis that identified the requirements of the permit. Several items were identified that overlapped and could be completed by Stormwater Program Coordinator Jeff Wiemer for all three entities.
These items included development of an outreach program, a public participation program, illicit discharge detection and elimination program, construction/post-construction site storm water control inspections and program record keeping. By combining these activities into one office, the estimated cost of the program was greatly reduced.
In 2019, the Regional Stormwater Program applied for and received a grant from the Washington Department of Ecology to purchase a new Schwarze A7 Tornado regenerative sweeper, replacing an older sweeper. The initial plan was to increase the lane miles swept by 100 lane miles each year. As a result, this would also help increase the total tonnage of contaminants removed from the roadway by 100 tons each year.
“We ran the new A7 along with our older 2007 sweeper, and we were able to pick up a total of 1,259 tons of material from our roadway and swept 1,344 lane miles. We vastly increased our lane miles swept in one year and exceeded our goal of an additional 100 tons each year,” Wiemer said.
The sweepings are processed at a regional decant facility constructed in 2016.
“We have been tracking that information ever since the start of our Operations and Maintenance program in May of 2013,” Wiemer said. “I believe that right now we have removed roughly 4,800 tons of material by sweeping and almost 1,200 tons from our vactor maintenance."
Public Outreach & Serving the Community
Unlike structural BMPs, street sweepers are able to serve the entire community. Storm water managers utilize them to meet another EPA mandated minimum control measure, public outreach. The city of Marietta promotes its “Clean Streets, Clean Streams, Clean Water” campaign, while in Asotin County, they promote the popular “Only Rain Down the Drain” campaign.