- The Stormwater Management StormFilter®
A water reuse system set up by Millennium Specialty Chemicals provides free irrigation for a public golf course, saving millions of gallons of water, and preventing toxic levels of metals from flowing into nearby Moncrief Creek. The system uses a multi-step process that includes a settling basin, UV disinfection, a passive StormFilter filtration system and non-contact cooling water.
Millennium Specialty Chemicals was having difficulty meeting National Pollutant Discharge Elimination System (NPDES) permit discharge limits for metals, primarily copper, at its manufacturing facility that uses groundwater for cooling. During the cooling process, evaporated water increases the metals concentration in the cooling water. Millennium discharges up to 250,000 gallons per day of non-contact cooling water and boiler- and cooling tower-blowdown.
Facing an $80,000 fine from the Florida Department of Environmental Protection (FDEP), Millennium chose to comply by participating in an in-kind water reuse project. They decided to install a system to treat the cooling water and provide a portion of the treated water, at no charge, to The First Tee of Jacksonville golf course for irrigation.
Millennium had been using a shallow, concrete basin that retained water for 120 minutes, allowing particulates to settle before discharging the non-contact cooling water into Moncrief Creek. Tests of the basin by the state in 1999 showed the water exceeding NPDES permit benchmarks for metal and bacteria levels.
Millennium attempted to meet permit limits by replacing the basin with a new collection pond that provided additional settling. Instead of two hours, the new pond held water for four to six days. While this improved the quality of the water being discharged, it was insufficient to reduce metal levels for compliance. The state required that Millennium add another level of treatment for compliance. “We did not want to go to chemical treatment because it creates more waste and is capital intensive,” said Mike Tipping, environmental manager at Millennium Chemicals.
Golder Associates Inc., an international environmental consulting firm with offices in Tampa, recommended the Stormwater Management StormFilter®. The StormFilter is a passive, siphonic, flow-through filtration system with a concrete vault that houses rechargeable, media-filled filter cartridges. As stormwater passes through customized media-filled cartridges, they remove suspended solids, oil and grease and adsorb pollutants like metals and nutrients. Contech recommended using layered perlite-zeolite media to physically filter sediment, removing oil and grease with perlite and metals by surface area contact and cation exchange with the zeolite.
Due to the volume of water being treated and the need for uninterrupted flow, recommended installing two parallel treatment trains to ensure continuous treatment and meet benchmark goals. Each filter train consists of two 8-ft. by 16-ft. pre-cast vaults holding 20 cartridges each for a total of four filter vaults and 80 cartridges on-site. From the settling basin, gravity routes water to one of the two parallel StormFilter trains using a timed control valve, which alternates flow between the trains at 12-hour intervals. A UV disinfection system installed between the settling basin and the filtration system kills microorganisms in the water, like algae and bacteria, before introducing the water to the filter units.
With the treatment system in place, the company wanted to dedicate a portion of the water for irrigating the nearby golf course. It built a new pipeline stretching more than a mile to carry treated water from the filtration system to the course. Millennium typically provides the course 125,000 gallons per day free of charge and discharges the remaining treated water into the creek. Without this water, the golf course would use groundwater for irrigation at a cost of thousands of dollars per year, further depleting this valuable water resource.
“Not only are we greatly reducing our discharge, but we are creating a lot of community good will,” Tipping said.
State statutes mandate that water reuse be an integral part of water resources management. The FDEP developed a reuse program as a means to reduce groundwater consumption. Through this program, reclaimed water is used for irrigation of public access areas, residential lawns and edible food crops. In 2002, the state reused about 584 million gallons of water per day.
The FDEP has strict procedures that ensure treated water is safe for use, including continuous monitoring of all reused water. In order to sustain compliance with its permit, Millennium regularly maintains its treatment system every 15 to 18 months. What started as a compliance issue turned into a collaborative effort between Millennium Specialty Chemicals and the FDEP. In compliance since installing the treatment system, Millennium has not only decreased the discharge into Moncrief Creek but reduced demand on natural groundwater.
“It was a positive experience all around,” said Tipping. “By participating in the water reclamation process we were able to get into compliance and also contribute to our community.”
- The Stormwater Management StormFilter®