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Institutional Case Studies

Bennington College

Bennington College Case Study When Bennington College's Vice President of Planning, Joan Goodrich, prepared to expand their college campus to house an additional 130 students she did not plan on upgrading the campus water system. However, the new housing would add another 130 gpm peak water demand and require a 275 gpm fire flow. And the existing water system was already at capacity.

The "typical" water system upgrade would require construction of one 300,000 gallon water reservoir with two totally separate fire and domestic water systems. The domestic system would require two water pumps each rated at 350 gpm with 14 hydro-pneumatic water tanks. The fire system would require one NFPA UL rated fire pump capable of 275 gpm with an NFPA UL standby generator. Because two separate domestic and fire distribution systems would be required, over 2,000 feet of new 8" water main would be needed for the fire system.

The installation of 2,000 feet of water mains would be very disruptive to the turn of the century campus. The grounds are well established with lawns, mature trees and a network of walkways and roads. There were also a myriad of existing underground utilities including water, wastewater, limited fire systems, steam heating systems, electric, telephone and cable services. Disruption to the college's normal operation would be overwhelming.

The standard approach offered a solution that was neither economically viable nor practical.

Enman Engineering proposed a solution reusing the single distribution system and adding three water pumps each capable of delivering 350 gpm. With any one pump capable of meeting the fire or the domestic demand, the need for an NFPA rated fire system and separate distribution system were eliminated. With any two pumps operating simultaneously both the domestic and fire suppression flows and pressure could be provided at any time. And the third pump provided the standby requirements to meet the Vermont Water Supply Rules.

Enman Engineering was not done with the innovation yet. The 350 gpm demand would require over 700 gallons of hydro-pneumatic storage tankage, 14 tanks each costing near $6,000. For about $30,000 variable frequency drive motors could be installed and the hydro-pneumatic tanks could be reduced from 14 to four. Not only did that save over $50,000 in tankage, but this reduced size of the pump house by about 120 sf, saving another $12,000. And, the variable frequency pumps would likely never run at full speed, except perhaps during a fire, substantially reducing the peak electrical demand diminishing power costs.

Enman Engineering, P.C. was proud to assist Bennington College in their efforts to increase their student on-campus enrollment