Title : Reverse Osmosis Unit-McMurdo Type : Antarctic EAM NSF Org: OD / OPP Date : November 10, 1992 File : opp93087 DIVISION OF POLAR PROGRAMS OFFICE OF THE ENVIRONMENT 202/357-7766 MEMORANDUM Date: November 10, 1992 From: Environmental Officer, DPP Subject: Environmental Action Memorandum (Installation of Reverse Osmosis Water Purification Unit at McMurdo Station, Antarctica) To: Safety and Health Officer, DPP Facilities Engineering Projects Manager, DPP Deputy Manager, Polar Operations Section, DPP Associate Manager (DOD), Polar Operations Section, DPP BACKGROUND Problems with the flash evaporators in McMurdo Station's primary seawater desalination plant have arisen. These problems were identified during a January 1992 on-site visit by the manu- facturer's technical representative. The representative noted extensive erosion of the interior walls of the flash evaporators. Currently, the evaporators are producing well below their rated capacity; they are expected to produce, normally, about 266,000- 304,000 liters (70,000-80,000 gallons) per day. These problems require actions to assure that sufficient potable water is pro- duced at the station to satisfy human water use and fire safety considerations. This Environmental Action Memorandum is tiered to the Supplemental Environmental Impact Statement (SEIS) for the U.S. Antarctic Program as well as to an environmental assess- ment prepared by the U.S. Army on use of Reverse Osmosis Water Purification Units. Alternatives Considered No-action. This option would leave the population of McMurdo Station without a reliable supply of potable water; Use of McMurdo's Old Water Plant. This old plant has been partially reconditioned for use as a backup facility. The plant could produce between 76,000-106,400 liters (20,000- 28,000 gallons) per day; the evaporators in the Old Plant must be cleaned, however, every two weeks. During cleaning those evaporators cannot produce water Use of one, temporarily positioned, Reverse Osmosis Water Purification Unit to satisfy the potable water and fire safety needs of McMurdo Station. The unit produces about 11,400 liters (3,000 gallons) of potable water per hour; or, about 273,600 liters (72000 gallons) per day--enough to satisfy McMurdo's daily potable water production under normal circumstances. Assessment of Potential Impacts Use of McMurdo's Old Water Plant. Brine from the seawater desalination process at McMurdo was determined to have dissolved solids concentrations slightly (up to 20%) higher than ambient sea water and, when generated by evaporator desalinators, greatly elevated temperatures. McMurdo's brine is input to the station's domestic sewage system allowing for dilution of the wastewater effluent. The SEIS noted that addition of residual, hot brine from both the primary and Old water plants, however, temporarily decreases mixing of the brine/wastewater effluent with cold, ambient seawater. The hot brine/wastewater effluent is temporar- ily more buoyant than the cold, ambient seawater. The beneficial aspects of wastewater effluent dilution with brine would be heightened if the brine were cooler. The SEIS noted no impacts related to the increased salinity of the residual brine. Use of Reverse Osmosis Water Purification Unit. The U.S. Army assessment noted potential impacts that relate both to flash evaporation and reverse osmosis technologies: 1) freshwater disposal of residual brine; and 2) engine (i.e., power produc- tion) emissions. The disposal of residual brine at McMurdo is to the marine rather than freshwater environment. Engine emissions for the reverse osmosis technology are not anticipated to exceed the complement emanating from McMurdo's power generation facili- ties (i.e., diesel engines) and used for desalination. Through air quality modelling, the SEIS noted that all U.S. air quality standards are met at McMurdo Station, at least at distances of 2 km or greater from the station (and probably within 2 km). Also, adding the relatively cooler residual brine that would come from the Reverse Osmosis Water Purification Unit to McMurdo's sewage effluent can be expected to allow more effective dilution and dispersion of the sewage effluent in ambient seawater. A number of chemical substances are used in connection with the reverse osmosis technology. Their potential environmental effects, if discharged to the marine environment, were evaluated through inspection of Materials Data Safety Sheets for each substance. This inspection, coupled with proposed use rates disclosed no potential for adverse effects. The substances are shown in Table 1. Finding The Environmental Officer believes from the information provided above that the temporary use of a Reverse Osmosis Water Purific- ation Unit would have less than minor and less than transitory impacts on the environmental media and biota near McMurdo Station, Antarctica. The Program is authorized to install and operate the Reverse Osmosis Water Purification Unit until such time that the station's primary water desalination facility is operable. Sidney Draggan Attachment Table 1 TABLE 1 Chemicals Used in Association With Reverse Osmosis Water Purification Units Chemical Name Quantity Remarks Accelerator for Glue Kit 252 grams Tank Repair Battery Acid 15.2 liters Electrolyte for generator Battery (D-size) For flashlight Battery (8-volt) For turbidimeter Battery (9-volt) For meter Calcium hypochlorite 23 kilograms 65% concentration Carbon, Activated 16 kilograms Carbon monoxide 1 cylinder Cartridge Element Air compressor Citric acid anhydrous 2.25 kilograms Cleaning solution Cleaning solution, Cuvette Acid, surfactant to clean turbidimeter Color Reagent 112 grams Color Test Kit Desiccant 3.8 liters Air Dryer Detergent 9 kilograms Membrane Cleaner Glycerin 504 grams Lubricant Methylethylketone 224 grams Tank Repair Methyl paraben 112 grams Eye Wash Reagent NTP-A (Organic acid) 30.4 liters Membrane Cleaner Polyelectrolyte 19 liters Cationic homopolymer Propylene glycol Droplets Preservative Resin,Ion Exchange 16 kilograms Rubber Adhesive 252 grams Tank Repair Rubber Cement 252 grams Tank Repair Sequestrant 3.8 liters Inhibitor Sodium bisulfite 12.6 kilograms Corrosive Sodium thiosulfate 112 grams Chlorine Test Kit Sulfamic acid reagent 100 pillows Chlorine Test Kit Sulfite reagent 100 pillows Chlorine Test Kit WD-40 1 can Lubricant