What lies on the horizon as the Board of Water Supply prepares for increasing demand and shrinking supplies?
Its capital improvement project (CIP) budget for 2002-2003 calls for spending nearly $60 million to design and build new facilities, keep old ones in good repair, and replace what can’t be fixed. Buried on the last page of the budget are costs associated with developing two new treatment facilities. There’s the installation of a granular activated carbon (GAC) treatment plant to remove volatile organic compounds from water pumped at the Ewa Shaft. With much of O`ahu’s central plain having seen heavy military and agricultural use, it may be disheartening, though not surprising, to learn that the Ewa Shaft water is approaching the point where it requires decontamination. (The BWS expects it will cost $660,000 for planning and engineering. No construction cost is provided in the CIP budget.)
What is new is Item 109 on the budget: “Makaha Well I Radon Treatment Facility.” Radon is a naturally occurring gas that has been linked to cancer. The Environmental Protection Agency is on the point of adopting a rule to limit the concentration of radon in drinking water, with most experts believing the final rule will set a limit of 300 picocuries (pCi) of radon per liter of water.
According to Mike Miyahira at the state Safe Drinking Water Branch, a part of the Department of Health, when the state did some preliminary screening for radon in water in 1987, Makaha water tested around 417 pCi/L. A more recent test that the BWS submitted to the state, in 1995, showed radon in Makaha water at around 292 pCi/L.
Such high numbers are not typical for the state, Miyahira said. Most water that was tested came in at under 100 pCi/L, he said. But, he added, “these were simple grab samples that may not be representative.”
Even though the Makaha well radon levels may be high for the state, they are well within ranges found across the continental United States. Generally, the older the geology of a given area, the higher the radon. Areas where wells pass through granite, such as in New England, have some of the highest levels, often exceeding 3,000 pCi/L.
Planning and engineering costs for the radon removal system are placed at $30,000 in the 2002-03 budget, but no construction costs are available. An internet search for methods for radon removal suggests that granular activated carbon is one of the most frequent means of treating this type of contamination.
According to the U.S. Geological Survey, radon, a water-soluble gas, emits high-energy alpha particles that can damage lung tissue. “The primary health risk from radon and its decay products appears to be from inhalation of the gas,” the USGS says, “although there is an increased health risk from drinking water with high concentrations of radon. Dissolved radon is easily released into the air when water is used for showering and other purposes.”
— Patricia Tummons
Volume 13, Number 11 May 2003
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