WATER EFFICIENCY – HARVESTING RAIN WATER FOR IRRIGATION
CB Richard Ellis; 1 Beacon Street
In 2012, while preparing for LEED Recertification at One Beacon Street, we discussed the potential for recovering rain water at One Beacon Street. We have approximately 5,000 sq. ft. of planter beds (including trees) that have required us to supplement with about 68,000 gallons of raw City water to irrigate annually (metered). During the summer months, Boston receives about 11” of rain a year. Our roof has 6 roof drains that each drain 5,000 sq. ft. of roof. By diverting rainwater from just two drains we expect to recover about 68,000 gallons a year. We only store about 3,500-4000 gallons at any one time (about 10-12 days of irrigation). 4,000 gallons weighs about 33,000 pounds (over 15 tons). To distribute additional tanks safely would take up too much valuable space. We are counting on frequent rain, throughout the summer, to keep the tanks full. The system went in to operation on Friday, May 17, 2013. During the month of May, we supplied 3,100 gallons of rainwater irrigation and ended the month with the tanks full from excess rain from the same period. In mid June, our vendor, Cityscapes, asked us to cut back on irrigation because the plants were getting enough water just from the rain.
As an added bonus, we have a full time car wash in the garage (1 man operation) located about 20 ft. from the irrigation system. We have a used meter we plan to install and the operator hopes to wash cars throughout the winter with rainwater. The system has the potential to collect more than enough rainwater on the off-season to supply the car wash. Historically, annual rainfall in Boston is 44”, (about 200,000 gallons.) in the off-season.