RTP Water Conservation Projects
As part of its environmental management system EPA’s largest laboratory complex in Research Triangle Park (RTP), North Carolina established the goal of reducing water use by approximately 7 percent in FY 2008. By implementing several water conservation projects, the RTP Campus was able to exceed this water savings goal.
In FY 2008, RTP reduced water use by 5,770,000 gallons per year, or approximately 12 percent compared to its FY 2007 baseline of 53,067,954 gallons by implementing the following projects:
Eliminating Single-pass Cooling
Single-pass cooling, in which water is used to cool equipment and then immediately discarded, was used in two laboratories in Building D until FY 2008. EPA eliminated these uses by switching to recirculating chilled water, saving 500,000 gallons of water per year.
Retrofitting Lavatory Faucets
The lavatory faucets in the RTP Main Building were replaced with faucets that have a flow rate of 0.5 gpm, resulting in water savings of approximately 500,000 gallons of water per year. The faucets in the National Computer Center (NCC) and Child Care Facility, which have maximum flows of 2.0 gpm, are scheduled to be replaced with high-efficiency 0.5 gpm faucets in FY 2009.
Eliminating Cooling Tower Use
EPA used to operate two two-cell cooling towers in parallel to cool a process water loop for experimental equipment in the RTP High Bay building. This cooling tower system operated more than necessary and at less than two cycles of concentration, which was not efficient water use. In addition, the towers were not maintained regularly. EPA turned off the two cooling towers in early 2008, saving 1.9 million gallons of water per year.
Cage and Rack Washing
Building A houses a laboratory animal care operation where animal cages are washed in two tunnel washers and racks are washed in two walk-in rack washers. Collectively, the cage and rack washing operation is the most significant use of water at the Main Building.
The operating schedule and operating sequence of the washers was optimized to minimize the consumption of water by adjusting the washing schedule from five days a week to four days a week. The optimization project results in water savings of approximately 1.6 million gallons of water per year.
Retrofitting Pre-rinse Spray Valves
A full-service cafeteria in Building C serves approximately 1,000 meals per day. Tableware is washed in a tunnel washer; EPA configured the washer to recycle wash water and use fresh water only for final rinsing. Pots and other large items are washed at three pot washing sinks, each equipped with a kitchen faucet and a pre-rinse spray valve. To achieve an estimated water savings of 60,000 gallons per year, EPA replaced non-water-efficient pre-rinse spray valves with high-efficiency nozzles flowing at 1.6 gpm or less.
Steam Sterilizer Controls
Seven steam sterilizers are located throughout the Main Building. In several instances, condensate tempering water was flowing continuously, even when the sterilizer was not operating. EPA installed retrofit kits to eliminate the continuous flow of tempering water in some cases, and in other cases instituted operational controls to limit cooling water flow to times when the sterilizer is being used. This saved approximately 860,000 gallons of water per year.
Reducing Vacuum Water
Building E features a central laboratory vacuum system with three liquid ring vacuum pumps operated in parallel. On each pump, seal water is recirculated through a tank and heat exchanger which is cooled with process chilled water to prevent excess heat build-up.
In November 2007, EPA adjusted the control timer sequence and reduced the water supply by two-thirds, saving approximately 340,000 gallons of water per year.
Looking to the Future
RTP plans to add to its success by implementing more water-saving projects. One project aims to leverage the location and storage capacity of a lake near the facility to supply the cooling tower from air handler unit condensation. The air handler units in Buildings A, B, D, and E, generate condensate water that could be reused in the cooling tower rather than going to waste. However, because the air handlers are a significant distance from the cooling tower, the condensate will instead be routed to the lake, and an equal amount of lake water will be drawn from a location near the cooling tower for use there. This project is projected to save at least 1.5 million gallons of water per year.