Project Database: CB Richard Ellis & One Beacon Street

WATER EFFICIENCY – HARVESTING RAIN WATER FOR IRRIGATION


PROJECT STORY

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.

CBRE - irrigation - 2 tanks

CBRE - irrigation - float in tank

CBRE - irrigation - piping

Environmental Impact

Remember the Three R’s: Reduce, Reuse and Recycle
In previous years we added efficient irrigation controls and drought resistant plants, reducing our water use from 100,000 gallons to 68,000 gallons per year.

MOST, if not all of the hardware for this project was made from recycled or re-used material including non-ferrous metals, flexible hoses (700 feet), and instrumentation.

Admittedly, the engineering staff aren’t happy with the Chief Engineer doing “Rain Dances” in the Control Room, because usually the results have been occurring during the weekends. However we are all very happy to be contributing to a sustainable future.

At some point we might discuss the addition of environmentally friendly nutrients to the water storage tanks to promote growth (soluble plant food). The downside of this is that the more plants grow, the more water they might need.

Cost

The approximate cost to install the system was:
(8) Tanks: $4,000
Pipe, meters, reducing valves, pressure gages, hoses, and valves: $2,500
Plumbing Contractor: $1,400
Structural Study: $500
Labor was done “in-house” and did not contribute to the cost: $0
Total Cost: $8,400
(Projected cost was $6,000 – we went a little over budget).

We had considered an alternate project to convert the planters to a drip irrigation system. It would have cost about $16,000 and reduced our irrigation needs by 50%.

We decided that the rainwater project was better for the environment and our budget.

Savings

We expect to save about 68,000 Gallons each year on our City water bill.
City water costs us $15.45 per thousand gallons.
Simple Payback: 68 * $15.45 = $1,050 (annual savings)
$8,400 / $1,050 = 8 Years

A unique aspect of this process is that we do not need water pumps (city or local) to irrigate. The building is over 500 ft. in height. The height of the tanks would develop about 260 psi due to this height. We are relying on gravity to do the work.

Incentives Received

We expect the Point for Innovation on the LEED Submittal to contribute to the ultimate resale value of the property. Also, LEED Certification is valued in the eyes of the tenants and prospective tenants and could result in added rental value to the building.