|One of the first CCWRRP stormwater projects completed this year was at Barley Neck Road in Orleans. The project took only 10 days to complete.|
by Chloe Wardropper, Conservation Intern, USDA Natural Resources Conservation Service
So far, this blog has told the story of the fish passage and salt marsh restoration components of the Cape Cod Water Resources Restoration Project (CCWRRP), but there is also a lot of work going on to improve the quality of water that runs off of roads after rainstorms. This water is referred to as “stormwater,” and when it is not treated, it has the potential to degrade the water quality of our saltmarshes.
In order to improve Cape Cod aquaculture and environmental health, the CCWRRP has now completed, or will soon complete, 19 different stormwater treatment projects in ten towns across Cape Cod!
Why is treating stormwater important? The simple answer is that Cape Cod’s economy depends on good water quality. Shellfishing is a multi-million dollar industry on the Cape, and it is only allowed in areas of excellent water quality. Shellfishing areas can be compromised when stormwater runoff from developed and paved areas carries contaminants such as nutrients, metals, fertilizers, and bacteria.
In a 2006 assessment, the Division of Marine Fisheries and town officials identified over 160 stormwater discharge points into shellfishing areas on Cape Cod. The CCWRRP prioritized 26 of these areas to install infiltration or constructed wetland treatment systems. When completed, these new systems will protect 7,300 acres of shellfish beds from contamination.
One of the first stormwater projects completed this year was in the town of Orleans at the end of Barley Neck Road on Little Pleasant Bay. Excellent water quality is a priority in Pleasant Bay as it supports a number of commercial aquaculture operations and many recreational shellfishers. The USDA Natural Resources Conservation Service and the Town of Orleans supervised the installation of two infiltration systems under the road to treat the stormwater from approximately 10,000 square feet of impervious runoff area.
How do these systems work? The design moves water, by a downward grade, along the side of the road to a concrete catchment basin. Here, the larger sediment sinks to the bottom while fluids flow into two big cement infiltrators (each eight feet wide by eight feet deep) that remove bacteria and other contaminants before releasing treated water into the sandy soil below.
As added protection, any water that is not caught in the first filter flows into a second catchment basin attached to another infiltration system. This infiltrator provides the same treatment, but requires less than one quarter of the vertical space of the first system to clean water. Consisting of a long plastic tube for water retention and filtration, this chamber must be shallower than the first infiltrators because it is closer to groundwater.
Construction of the Barley Neck Road project was completed in July 2011. It took only 10 days for the contractor to prepare the site, dig holes for the catchment basins and infiltrators, install the systems, and repave the road with appropriate grading.
Approximately 150 acres of shellfish beds impacted by runoff from Barley Neck Road are now free of stormwater contamination, according to ongoing Division of Marine Fisheries monitoring in Pleasant Bay.
When you walk by the site, you barely know anything is there. A manhole cover is the only visible evidence of the extensive filter systems doing their important work underground.