CONSTRUCTION OF A BIOFILTRATION SWALE

Best Management Practice Demonstration Horse Farm

Construction of a Biofiltration Swale

Stormwater management is a growing concern for equine facilities.
Regulators are concerned that stormwater runoff carries nutrients and pathogens from these facilities into local streams and lakes.
Equine facilities such as the Equine Science Center can be considered a source of bacteria and nutrients for non-point source pollution.
As the runoff water travels over the surface of a equine facility it collects soil, nutrients and bacteria from the surface.
Eventually, the runoff flows from the site through a pipe that leads directly to Weston’s Mill Pond. The runoff is not treated before it discharged. The runoff carries the soil, nutrients and bacteria when it flows into the pond thereby threatening the health of this waterway.

Several studies have shown that swales with weirs can significantly improve the quality of the runoff traveling through it.
Other studies have shown that swales are very effective at increasing infiltration rates for a site. The swales are designed with tall native grasses that have long roots that encourage infiltration. The longer the runoff is exposed to the swale the greater the chance the runoff will be infiltrated.
This swale will be equipped with monitoring equipment to document how effective the project has been at improving the water quality of the runoff.

The bioswale was designed and constructed to collect the stormwater runoff from the surrounding paddocks and treat it before the water is discharged to the local waterway.
A bioswale is a shallow channel of graded soil with vegetation. The swales are graded at a shallow slope and often have meandering paths. The vegetation along with the shallow slope and meandering path is meant to lengthen the distance the runoff travels before it hits a local water way, thereby increasing the chance it will infiltrate before discharging to a local waterway.
The bioswale is 33 feet wide and 850 feet long. The swale begins upstream of the roadway and travels underneath the road to end of the Equine Science Facility to a stormwater sewer inlet.
A sandy soil mix with a 10 to 15% organic content was used in the bottom of the bioswale, which was covered erosion control matting.
Native grasses (Soft rush and Switchgrass) were planted along the berm and bottom of the swale.
The bioswale was designed to handle the stormwater runoff from the paddock that would result from a New Jersey Water Quality Design Storm (1.25 inches of rain over two hours).
Since approximately 90% of New Jersey's rainfall comes in storms less than one inch, the rain garden should capture and treat 90% of the stormwater runoff from the front paddock area.

Slideshow of the construction of the bioswale

Two automatic samplers have been set up by the inlet and outlet of the bioswale.
The automatic samplers will monitor the elevation of the water at the inlet and out of the bioswale. Researchers will calculate the amount of water that travels through the inlet by using the recorded elevation and weir equations.
The automatic samplers are programmed to collect water samplers every thirty minutes during a rain storm. The samples from the inlet and the outlet will be analyzed for nutrients and bacteria.
The results from inlet and outlet of the bioswale for the nutrient and bacteria tests will be compared to look improved water quality as the runoff travels through the bioswale. The flow calculations at the inlet and outlet will be used to measure any infiltration that occurs in the bioswale.