D.7.5 Plumbing and Water Use
Water conservation procedures currently being implemented at Fort Carson decrease maintenance and life cycle costs for building operations and help achieve the water conservation goals of the Post. In addition, facilities that use water efficiently reduce overall costs to Fort Carson by lowering water use fees, volumes of sewage to treat, energy and chemical use, and capacity charges and limits.
D.7.5.1 Indoor Plumbing Fixtures
Federal law mandates that all plumbing fixtures meet or exceed the minimum Energy Policy Act of 1992 (EPACT) requirements. Specify fixtures that exceed the EPACT requirements, including dry fixture and control technologies, in all new Fort Carson buildings. Note that water-efficiency measures in buildings can easily reduce water usage by 30% or more. In a typical 100,000-ft2 office building, low-flow fixtures and equipment can save 1,000,000 gallons of water per year or more, based on 650 building occupants each using an average of 20 gallons per day.
There will be no reuse of plumbing fixtures in remodeling or new construction on Fort Carson.
Lavatory and bathroom faucets and aerators will have a maximum flow rate of 2.0 gallons per minute at a flowing water pressure of 60 psi. Automatic shutoff faucets, preferably sensor operated, with premixed temperature control are required.
Toilets will deliver a maximum of 1.6 gallons per flush.
Urinals will deliver a maximum of 1.0 gallons per flush. Automatic sensor operated valves are required. Waterless urinals are preferred.
D.7.5.2 Water-Consuming Mechanical Systems
Cooling towers are the most common type of cooling system for large cooling loads. Make-up water must be added to cooling towers to replace the water lost by evaporation, bleed-off, and drift. Operate cooling towers at the highest possible cycles of concentration to save water.
Sources of make-up water for cooling towers can be once-through cooling system, process wastewater, and treated municipal wastewater effluent. The most water-intensive cooling method is once-through cooling, in which water contacts and lowers the temperature of a heat source and then is discharged. Eliminate once-through systems when possible. If it is not possible to eliminate these systems, then integrate shut-off devices to prevent the water from running when the once-through unit is not operating. Also consider converting once-through systems to recirculating systems by connecting them to cooling towers or chilled water systems.
Steam boilers require make-up water to replace blowdown water (periodically released from the boiler to remove accumulated solids and sediments), or to compensate for uncollected condensate (in steam generator systems). The following water conservation and recycling/ reuse options are applicable for boiler and steam generator applications:
-
Consider a condensate return (recycle/reuse) system that enables otherwise uncollected condensate to be returned as boiler feed or cooling tower make-up water.
-
Employ an expansion tank to collect boiler blowdown water and permit cooling (rather than mixing cold water) for recycling/reuse. Consider use of a heat exchanger to preheat boiler feedwater and cool blow-down.
-
Depending on water quality considerations, condensate and blow-down may be used for other nonpotable- water-consuming applications.
Consider the reuse of once-used deionized water for a different application because deionized water is often more pure after its initial use than municipal. Also consider using reject water from reverse osmosis (RO) systems.
First minimize the quantity of wastewater generated, then implement recycling/reuse of the unavoidably generated wastewater. Consider the following water-efficiency with features and techniques when selecting HVAC equipment and other industrial processes and equipment:
-
Avoid single-pass or “once-through” process cooling systems. Consider multi-pass, recirculation, or cooling tower systems.
-
Consider connecting equipment to a closed-loop system rather than using a potable water source.
-
Adjust overflows from recirculation systems by controlling the rate at which make-up water is added: install float-controlled valves on the make-up lines, close filling lines during operation, and provide surge tanks for each system to avoid overflow.
-
Install high-pressure, low-volume nozzles on spray washers.
-
Avoid high-volume hoses with high-pressure. Consider low-volume cleaning systems.
|