City & County of Denver Wastewater Yard, A Stormwater Project Profile
Just 15 feet from the edge of the Colorado Rocky Mountains’ most historic and vital river sits one of the most tested stormwater devices in the country. Dozens of these designed/engineered stormwater filtration systems have been installed and are currently serving various parts of the country, however, this one in particular is special. This unique stormwater filtration system has a very successful history. Before entering real-world service, it had already met exceptional challenges.
Good Harbour Laboratories, an independent technology testing company in Mississauga, Ontario, conducted 33 test runs of this exact Kraken Membrane Filter, which now protects Denver, Colorado’s South Platte River. After 33 intensive tests, the system never wavered, clogged, or went into bypass, and ultimately, “the total mass of sediment captured was 434 pounds and the overall removal efficiency was 89%”.1 During the final test runs, the unit was peaking in the high 90s for removal efficiency.
As its name implies, every Kraken stormwater filtration system is a “beast” – not in size, but in work efficiency. Kraken Membrane Filters sit within a relatively small footprint, but they can treat monster flow rates and large pollutant concentrations (TSS Removal) and remove up to 99% of trash.
Comparatively, other membrane filters require deep sumps, deep excavation, and intense time-consuming maintenance. Deep sumps also mean that standing water and submerged filters will quickly deteriorate and develop biofilm as they sit and soak in festering water for long periods of time. Kraken filters are designed with a drain-down, resulting in no standing water, which avoids vector control issues (mosquitos) and eliminates pools where organic material can break down and cause further odor nuisance and pollution.
As water comes off the foothills of the Rocky Mountains, multiple rivers and creeks converge into the South Platte River and begin to flow east. As the river grows, it veers north at a nearly perfect right angle and begins its journey through Denver. The South Platte River has always been a vital Colorado resource, irrigating the downstream agricultural industries of the Piedmont Plains, Nebraska Plains, and the eventual Missouri River. The river is also widely used for recreation, and although it is “a principal source of water for eastern Colorado…the South Platte River through Denver is on the EPA’s list of impaired waterbodies.”2
With their offices located adjacent to the South Platte River, the City & County of Denver’s Wastewater Management Division has a focused interest in the health of their river neighbor [See Diagram A]. These offices are home to operational and administrative staff and personnel, but there were plans to base the county’s massive roadway maintenance sorting yard merely 15 feet from the river’s edge – and it would qualify as a “Point Source” for pollution. According to the EPA, “Point sources of pollution are pipes and drains that flow directly to a state water and typically come from industries, some agricultural facilities, and municipalities. Storm sewer systems that discharge to a state water are point sources of pollution.”3 Run off from these sites needs to be permitted, therefore uncontrolled and untreated stormwater is highly prohibited, and only proven treatment devices are approved, trusted, and capable.
The challenge for this Kraken would inevitably be a confrontation with every raw, decaying, and disposed material and chemical related to maintenance of the county’s roads. Denver’s Wastewater Management Division yard would remain an unpaved disposal site covered in loose dirt, sediment, and mounds of demolished road debris – tons of old paving materials, asphalt, cement, and pipes – that will lay in wait for disposal or reuse. Again, this is merely 15 feet from one of Colorado’s most precious and widely used natural resources.
According to www.colorado.gov and the Colorado Water Quality Control Board, “Polluted stormwater runoff can have many adverse effects on plants, fish, animals, and people, such as the following:
- Sediment can make it impossible for aquatic plants to grow, and can destroy aquatic habitats.
- Excess nutrients can cause algal blooms.
- Bacteria and other pathogens can wash into swimming areas and create health hazards.
- Debris and trash…washed into water bodies can choke, suffocate, or disable aquatic life like ducks, fish, turtles, and birds.
- Household hazardous wastes like insecticides, pesticides, paint, solvents, used motor oil, and other auto fluids can poison aquatic life. Land animals and people can become sick or die from eating diseased fish or polluted water.
- Polluted stormwater often affects drinking water sources. This, in turn, can effect human health and increase drinking water treatment costs.” 3
Each adverse effect poses a serious potential risk. If addressed inadequately, the damage could be extensive, long-lasting and cost the county and community. Upon continued heavy rains and the first flush, the challenge for the Kraken filter will be to treat heavy flow rates and large pollutant concentrations, from a site filled with mountains of waste and dirt. The Kraken will be evaluated on how well it handled these challenges, but also its ability to be maintained effectively. The Kraken’s challenges have many factors, and the city and county officials needed a comprehensive and proven solution.
Laddie Fromelius, of Bio Clean Environmental, is a veteran of the stormwater industry and a Denver local who knew the city would be skeptical. This was a massive challenge and City & County of Denver maintenance crews were only familiar with cartridge based media filter systems whose cleaning and maintenance processes were labor intensive, frequent, and problematic. They had struggled for years, with far from practical solutions – as cartridge based media filters required more intense labor and a more frequent maintenance regiment than the city budget had planned for. “The city and county could really benefit from witnessing the immense differences a Bio Clean Kraken filter would offer them,” Laddie remembers stating. He knew what the Kraken Membrane Filter’s capabilities were and what it could do – to not only address the challenges of the site and its pollutants, but satisfy the crews tasked with maintenance.
Soon enough the very system that had surpassed all testing expectations on its way to NJCAT Verification & NJDEP Certification, would be set in the ground along the South Platte River. Donated to the county by Bio Clean (as a pilot project), the NJCAT/NJDEP Kraken filter had all of the confidence of the most stringent removal verifications and certifications behind it, and it went to work. Laddie added, “Passing the New Jersey Department of Environmental Protection’s strict protocols, means the Kraken filter’s qualifications are authentic and these diligent agencies have certified its effectiveness to remove 80% of the Total Suspended Solids. This is a very specific particle size distribution and a vital credential for any system trusted to protect our environment.”
After one year on the job, the Kraken filter received its first review and maintenance [Note the pictures above]. Each of the 16 filters was completely black, but the system never failed or went into bypass. Filter cleaning was simple. Each filter was rinsed on-site at a wash bay connected to the sanitary sewer system. This meant the Kraken’s captured stormwater pollutants were rinsed and released into the sanitary treatment plant [Pictured above], the proper way to dispose of this material. After three city crew members performed two hours of maintenance, the system and filters were clean and as good as new. Proving again that every Kraken Membrane Filter, although compact, is a beast. There were many challenges and adverse factors that could have easily overwhelmed other systems, and many seasoned engineers thought it could happen to the Kraken. But after Good Harbour’s and this extreme real-world test, the Kraken has etched its name as the ultimate cost-effective, low maintenance, and highly reliable stormwater BMP.
1. NJCAT Verification Certificate: Kraken Web Page
2. South Platte River Wikipedia
3. Colorado.gov Water Quality Control Division Fact Sheet [Page 5]
The Kraken is an efficiently engineered stormwater membrane filter that provides high flow rates and over 170 sq.ft. of surface area.This much filter surface area allows it to operate at a loading rate of only 0.05 gpm per square foot, to ensure maximum performance and minimum maintenance. The Kraken Filter’s low loading rate allows it to keep maintenance needs low and prevent clogging issues often found in other filter systems advertising high loading rates.
- Small Footprint Reduces Installation Costs
- No Deep Sump Chamber Reduces Costs
- Reusable Catridges Are Easily Cleaned
- Fast & Simple Maintenance
- Clean Chamber Easily with a Standard Vacuum Truck