Biofiltration at Winter Island Park in Salem, MA



Case study: filter stormwater to increase water quality

The client contacted ACF/Ferguson Waterworks for assistance in finding a solution for a stormwater concern at Winter Island Park, a historical recreation site. Untreated stormwater was flowing off approximately 2.5 acres of buildings and parking lots, emptying directly into Salem Harbor.


The runoff decreased sea water quality due to sediment, bacteria, metals, oils and grease. This affected important shellfish, waterfowl habitats and fisheries. In addition, surrounding parking lots were experiencing severe ponding.


The client desired a cost-effective system that would filter stormwater to increase water quality while also fitting into the limited space available.



Solution and installation: FocalPoint

After careful consideration, FocalPoint biofiltration system was chosen to treat the polluted runoff and slow the rate of discharge into the harbor.


FocalPoint combines next-generation biofiltration media with a high-performance underdrain to deliver all the advantages of a traditional bioretention system—while being up to 90% smaller than competitive products.


A domed overflow riser with a filter insert was added to the installation to collect any floatables and mulch. Overall, the installation took less than a day.




The biofiltration system reduced parking lot water ponding and bank erosion, as well as significantly removed a number of pollutants.


There have been several major storms since the system was installed, and FocalPoint has performed exactly as designed. The client was elated that the system has helped improve the harbor’s water quality while maintaining the integrity of the historical site.


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