Stormwater Control and Green Infrastructure Project

The Stormwater Control and Green Infrastructure Project maintains the integrity of water quality in Hamilton County by addressing stormwater issues at Arrowhead Park, Town of Inlet. Arrowhead Park has a large public parking lot and hosts the municipal building, seeing a lot of traffic. The installation of green infrastructure technology at Arrowhead Park captures stormwater runoff from impervious surfaces, prevents flooding, and decreases the amount of pollutants entering the Fourth and Fifth Lake Channel. Having the green infrastructure installed in such a public, high traffic place is a very important learning and educational opportunity. This project will serve as a demonstration of ways to effectively reduce stormwater runoff while using green infrastructure technology. The District consulted with the Warren County Soil and Water Conservation District, whose staff has expertise with utilizing green infrastructure to reduce stormwater runoff. The Town of Inlet Highway Department and Parks and Rec provided crew members and equipment to assist with project installation.

Stormwater Control and Green Infrastructure Installation

• Step 1: survey property and look for areas that would benefit from green infrastructure
• Step 2: remove impervious surfaces by excavating the landscape to desired depth
• Step 3: lay down the geotextile fabric liner to act as a barrier between subsoil and rocks
• Step 4: place uniform stone ¾-inch diameter on top of liner and tamp down
• Step 5: install TRUEGRID® PRO PLUS® permeable pavers on top of rock base
• Step 6: place uniform stone ½-inch diameter on top pavers and tamp down

Rocks were of the same size to limit compaction as much as possible and increase void space, allowing for maximum stormwater and flood infiltration during a storm event. The TRUEGRID® pavers have 40% – 60% void space that fills with water during a storm event. The fabric allows water to percolate into the subsoil at its normal rate. All of this open pore space collects a large volume of water without an issue. The project site is like a reservoir for stormwater runoff and flood waters.

Tangible Outcomes

• A 1,200 ft2 area of TRUEGRID® PRO PLUS® permeable pavers was installed at the municipal center
• 100% of stormwater runoff is captured from .25 acres of impervious surfaces during 1.5″ storm event
• This is the equivalent of approximately 7,100 gallons of water that is infiltrated into the pavers instead of running off into the Fourth and Fifth Lake Channel