Gravel Wetland on Golf Course

Gravel wetlands remove nitrates from streams and drainage outflows. The University of New Hampshire Stormwater Center team designed this unique filtration system that works like this:

• Piped water enters a forebay, a 30 feet by 40 feet, five foot deep, grassed containment structure. This allows debris and sediment removal before entering the main containment area.

• Next, the water is piped into a 120 feet x 40 feet gravel wetland. This grassed structure is built with 24″ of 3/4″ stone, topped with 3″ of 3/8 stone (used as a bridge). An intricate piping system directs the water into the bottom of the 3/4″ stone layers where hungry bacteria consume nitrates.

• The stone is surfaced with 8″ of an organic plantable soil that we will plant with wetland shrubs.

• The water exits through a 12″ pipe that leads into a concrete manhole that terminates at stream discharge invert.

The completed installation has sodded slopes.

Gravel Wetland Under Construction

Gravel Wetland Subgrade Excavation