The StormTreat system is a unique stormwater treatment technology that combines several processes into a single unit. It is meant to be a first flush collection and cleansing system that is capable of removing grit, suspended solids, petroleum hydrocarbons, metals, nitrogen, phosphorous and bacteria. The system includes sedimentation chambers, and a biological filter capable of sustaining wetland plants as well as a built in an oil and grease separator.

The unit is 9.5 feet in diameter and 4 feet high. Depending on the area to be treated, any number of units may be used. Stormwater enters at the bottom of the unit through a PVC pipe connected to the central sedimentation chambers, which are configured like a pie with six sections. Influent first passes through a bag filter (see 2) that collects grit and large debris. The influent is then directed through floating skimmers around the sedimentation chambers, which are separated by solid bulkheads (see 4). The skimmers retain oil and grease by transferring clarified water from 3-4" below the surface of the water to the next chamber. The final sedimentation chamber outlets to a slotted PVC pipe extending into the biofilter (see 5). The biofilter surrounds the sedimentation chambers on the perimeter of the unit occupying roughly the entire radius of the unit (see 6). The biofilter contains a gravel matrix with an effective aggregate size diameter between 3 and 5 mm. The biofilter is designed to support facultative wetland plants such as bulrush. Effluent is directed in a counter clockwise direction through the biofilter to a slotted PVC pipe (see 7) and then out an outlet pipe with an adjustable valve for closed mode discharge (see 8). Lineal distance of the biofilters is approximately 25 feet. The flow rate on the outlet is adjustable, but the manufacturer recommends that the outlet flow rate be set at 0.25 gallons per minute, which would result in a 4 day residency time at full capacity. The outlet valve can also be closed for containment purposes in the event of a hazardous waste spill. Treated effluent is discharged from the biofilter via slotted PVC pipe located at the top (see 9) and bottom (not shown) of the unit into another slotted PVC pipe located outside the unit in the surrounding gravel. The outlet of the biofilter is 6 inches above the bottom of the unit to allow sufficient water for plant growth between storm events.

The StormTreat system is set into the ground in a granular fill which makes it convenient to place. You don't need a wetland, you can install one in a parking lot or yard.

Maintenance of the unit entails inspection after major storm events and inspection of baffles, skimmers, and control valves yearly. Replacement of the grit bag filter and sediment removal is recommended every 5 years by suction pump. Replacement of sand media should take place every 10-20 years, which would also require re-establishment of the wetland plants.

Wetland plants grown in the outermost chamber are equivalent to a constructed wetland and, therefore, treat the stormwater as a biofilter (above). Installation of units at the Kingston site.

As a test installation, the unit was used in an environmentally sensitive area by the Jones River in Kingston, Massachusetts. Stormwater was collected from approximately 73,000 sq. ft. of impervious area, including: 2,000 sq. ft. of road, 4,500 sq. ft. of parking area at a municipal building, and 14 private driveways. The installation consisted of four units, installed in parallel, and fed centrally by the terminal catch basin with 4" PVC lines feeding each unit. The mean percent removal rates for Fecal Coliform, Nitrogen and Phosphorous were 97%, 77% and 90% respectively. The system also removed 77% of heavy metals.

In 1999, StormTreat Systems was awarded the Environmental Technology Innovator Award and is the first stormwater treatment technology to be verified by the Massachusetts STEP Program (Strategic Environmental Partnership). LASN

Information provided by Eco-Cycle, Inc. 877-787-6426 and the Massachussets STEP Program's report of StormTreat.

Eco-Cycle, Inc. is currently looking for sales representatives on the west coast.