Wetland Studies and Solutions, Inc. (WSSI) recently installed an additional rainwater harvesting system at our Gainesville, Virginia office to further our commitment to sustainability and low impact development. WSSI's LEED^® Gold-certified headquarters already collects rainwater from the roof in an 8,000-gallon cistern buried behind the building for irrigation. The new 4,000-gallon cistern, installed in WSSI's warehouse, collects additional water from the roof. This cistern is plumbed into the building to supply water for each of the ten toilets in the office area, with four waterless urinals already in use.

 

Even Woodrow and Hoover know to follow important signage for non-potable water. The newly-installed 4,000-gallon cistern is tied into three of the building's five roof drains, which collect rainwater from nearly 18,000 square feet of the building's 28,000-square foot roof. Water collected by the three roof drains passes through two vortex-style filters (which eliminate coarse debris) before it is stored in the cistern. Since the rainwater collected is clean and is not being used for potable uses, no additional treatment is needed. The use of rainwater to flush the toilets is expected to reduce the amount of potable water that is brought into the building by more than 60,000 gallons per year. Reducing the amount of potable water used for the toilets reduces the amount of energy required to treat water off-site and transport it to the building while preserving our water resources. Overflow from the cistern is tied into the buried irrigation cistern, which in turn overflows into the raingarden, increasing the rainwater collection capacity on-site and reducing the amount of site runoff.

Enlarged non-potable water sign. The rainwater harvesting system was put into operation on April 24, 2009. If the volume of rainwater within the cistern is depleted during dry periods, the municipal water supply will automatically feed the office toilets. Based on a sizing analysis, it is estimated that the cistern will be dry an average of four days per year. WSSI sized the cistern to provide capacity for approximately three weeks of estimated usage and it requires only 0.5" of rainfall to fill completely. The cistern was sized based on an analysis of the past 40 years of rainfall as measured at Washington Dulles International Airport and by considering both the current building occupancy and potential growth. Warehouse space constraints and an economic analysis also helped lead to the decision to use a 4,000-gallon cistern. For more information, contact Russ Dudley, Jennifer Brophy-Price, or Mike Rolband.