Guest Post: NVCC Rain Collection Project

By Dan Culligan

 A group of students from Naugatuck Valley Community College, together with NOFA, recently designed and constructed a rain collection system on the campus of NVCC. Under the direction of Jenna Messier (Organic Land Care Program Director: NOFA) and Mike Schwartz (Academic Assistant of Horticulture: NVCC), the students (Ben Carroll, Kyle Denny, and Dan Culligan) were responsible for organizing materials and constructing the system. The primary goal of this project was to capture as much runoff as possible from the impermeable surfaces on campus and keep it from entering into Welton Brooke, Hop Brooke, the Naugatuck River, the Housatonic River and ultimately Long Island Sound during a rain event. Of course a secondary benefit of the project was the utilization of the captured storm water for watering gardens around the campus, thereby diminishing the schools use of the municipal water supply.  

Wading across the pond to install downspout underneath walkway

The team installing pipe

            In planning for this project, the group took into consideration a number of environmental factors that would influence the design and placement of the rain water collection system.  One of the factors that had been considered was the surface from which the water is collected. This meant that ample water would need to collect on the surface during a rainstorm to justify having the system in that particular area. The location of the system was also critical; because it had to be in a place where the rain water runoff was entering a waterway that would eventually travel into the Long Island sound. The holding capacity of the collection tank and the distance it is away from the nearest waterway is also critical; in the event that the system reached full capacity and overflowed there needed to be ample distance and other permeable surfaces surrounding for the excess water to enter the ground first.

The way to calculate approximate amount of water runoff in gallons on any impermeable surface is to use this equation: Harvested Water = Catchment Area (ft2) x Rainfall Depth (in.) x 0.623 Conversion factor.  Although the goal is to reduce storm water runoff, other unintentional benefits exist. Water conservation is a positive outcome and is also especially important for large institutions such as NVCC due to the sheer volume of people attending the school. In 2010, there were approximately 7,000 students attending the college. A large student body combined with thirteen horticulture gardens, numerous landscaped areas, 4 greenhouses and the Tamarack Arboretum command a substantial amount of water usage.

The first step in the construction process was to choose a location where storm water runoff could be diverted and collected. Upon studying the existing layout of the campus, the decision was made to make use of an elevated concrete pedestrian bridge that was discharging nearly 100% of the storm water that hit it directly into Welton Brook, which is the body of water the bridge goes over.  The location and engineering of the bridge along with its surrounding topography made this location a very obvious place for a water catchment system to be installed and utilized. The bridge starts near the main entrance of the school and ends at the entrance to the student center building. The dimensions of the walkway are approximately 130’ x 12.5’. The bridge was equipped with drains to prevent water buildup on the surface and freezing in the winter. The problem was that the drains were open on the bottom and spilled out directly into or very near the edge of Welton Brook and the pond it creates right below the bridge. The group decided that utilizing the existing drain structures in this location was the most practical way to design the catchment system. Consideration was taken to optimize cost, labor intensity, and collection volume based on the surface area, the location of the walkway and the existing configuration of the drains. This arrangement allowed for a relatively simple and effective design.

Pipe under walkway that will bring water to 550 gallon catchment tank

Once the targeted area was established, the next step was to design the system itself and estimate the cost for materials. In a one inch rainstorm there is a potential of collecting over 1,000 gallons of water. The collection basin used was a 550 gallon plastic water tank, and the system was made predominately out of PVC pipe due to its availability and budget friendly pricing. Some simple drain pipe extensions were attached to each of the five existing drains on the bridge, and then tied into one single main drain line using elbow and Tee connectors. All fittings were glued together to ensure

security and maintain a water tight seal.  Metal straps were screwed into the concrete, which support the pipes under the drains. The actual construction of the project took the group approximately four days to complete, costing under $1000 in materials.

When the campus experienced its first rainstorm with the new system in place it was found that in less than a day of heavy rain the entire basin had been filled. This means that 550 gallons of storm water had been successfully withheld from entering the surrounding waterways which has been raising concern amongst environmentalists in recent years.  That stored water will now be used by the college to irrigate at least two of its horticultural gardens located within a garden hose length from the tank.

The team intentionally designed the system to allow for additional tanks to be joined to the one they installed in order to collect and store even more water.  During the primary survey of the campus there were also several other locations identified where impermeable surfaces come into close contact or discharge directly into Welton Brook.  These locations can easily be used in the future as sites for rain water collection systems. The team made a list of these locations and provided it to the campus director of facilities.

              The work done at NVCC shows how a small investment can make a big difference.  This hopefully can serve as an example for other institutions, industrial buildings and residential homes to not only reduce the amount of runoff going into Long Island Sound but also to be better stewards of the water resources they have available to them for free, which can be applied to a multitude of creative uses. Through the construction of this system students of the college who are being trained for the green industry now have a great example of how a storm water collection system works and the benefits of including similar systems in their own projects in the future.

550 gallon tank that will catch rain water from walkway above campus pond

Downspout leading to catchment tank