THE VIRGINIAN-PILOT
Copyright (c) 1994, Landmark Communications, Inc.
DATE: Tuesday, July 5, 1994 TAG: 9407050061
SECTION: FRONT PAGE: A1 EDITION: FINAL
SOURCE: BY JAMES SCHULTZ, STAFF WRITER
DATELINE: VIRGINIA BEACH LENGTH: Medium: 96 lines
On a hot, thirsty day, stroll to the ocean, empty glass in hand. Dip it in the surf, fill it full and drain it in one swallow.
If only finding a cool drink of fresh water were so easy.
Now that the Lake Gaston pipeline project appears indefinitely clogged, Virginia Beach officials fret that potable water soon will be in short supply. Dry weather hasn't helped; despite scattered downpours, parts of Hampton Roads are teetering on the edge of drought.
Water restrictions, already in place, could be broadened.
So what about those trillions and trillions of gallons of seawater shimmering just off the coast? Couldn't the ocean be shaken free of its heavy concentration of salt and minerals and used to slake thirst, nourish lawns and clean off car dirt?
Maybe - but at a steep price.
``If we thought we could desalt ocean water and not break the bank, we would have already done it,'' said Thomas M. Leahy, a water resources engineer for Virginia Beach and vice president of the American Desalting Association. ``(A desalting) project could take on the costs of the magnitude of the Southeastern Expressway. You're talking a project approaching half a billion dollars.''
A desalting plant could be the size of a high school, produce about 50 million gallons of fresh water a day (current city use is 30 to 35 million) and cost as much as $400 million to build. Operations and maintenance would cost extra. Electricity rates could also climb because of the extra power needed for the desalting plant.
For Beach citizens footing the bill, Leahy said, water bills could double or triple, from an average of $25 a month to as much as $75. The latter amount would kick in only if residents received all their fresh water from the sea. Other options - half from the ocean, for example, and half from reservoirs and underground aquifers - could reduce monthly costs to $50.
Environmental concerns could also delay or scuttle any ocean-water desalting plan. Concentrated, brine-laden liquid, the by-product of purification, is extremely salty and larded with potentially toxic materials and metals such as arsenic, mercury, copper and silver.
``Any water-related alternative requires most of the same permits we've been trying to get for the Lake Gaston pipeline,'' Leahy said. ``There could be significant regulatory opposition.''
Technological advance has been slow but steady, as engineers develop new materials and more efficient processes. Desalting has traditionally been so expensive because only costly metallic alloys can withstand the corrosive effects of ocean water as it's boiled to steam and then condensed, one of the two primary desalting methods.
The other approach is called reverse osmosis, a less expensive process that essentially filters seawater through porous membranes. RO, as it's also known, is used by Virginia Power's Chesapeake Energy Center near the Gilmerton Bridge. There, a reverse-osmosis unit removes impurities from drinkable Chesapeake city water before it is used to power steam turbines. The ultrapure water saves wear and tear by reducing the buildup of potentially damaging minerals on turbine blades.
``There are a whole lot of factors determining use of reverse osmosis,'' said Rod Beard, a Virginia Power chemistry supervisor. ``We didn't say, `Yeah, let's go ahead and put in RO and save us a lot of money.' We had to analyze the water and the membranes.''
By 1990, according to figures from the International Desalination Association, some 120 countries used various processes to produce fresh water from the sea. Not surprisingly, desert countries in the Middle East lead the pack, with Saudi Arabia the biggest producer of desalted water.
There is no large-scale desalting plant in the United States. Several, in such states as California, Florida and North Carolina, produce drinking water, but in the range of only a few million gallons a day.
Despite the obstacles and expense, a dry world may have to turn to desalting technologies to keep both people and crops watered. But desalting tens of millions of gallons daily at a single plant may be a long time in coming, says a national desalting expert with more than 30 years' experience in the field.
``Once the rains come, no one wants to discuss (desalting) anymore,'' said O.J. Morin, a senior water-treatment specialist for the engineering firm Black and Veatch. ``Nobody wants to desalt unless they have no other way to get water.'' ILLUSTRATION: Graphic
STAFF
REVERSE OSMOSIS: CHANGING SALT WATER INTO DRINKING WATER
SOURCE: The New York Times
[For complete graphic information, please see microfilm]
WHY NOT DESALT?
COST: Water charges could double or even triple.
BIOHAZARDS: Brine from desalting contains potential toxins, such as
arsenic, copper, silver and mercury.
DELAYS: Regulatory hurdles would have to be overcome. Approval, if
it came, would like take years.
by CNB