Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: MONDAY, April 8, 1991 TAG: 9104080040
SECTION: VIRGINIA PAGE: A3 EDITION: METRO
SOURCE: JOEL TURNER MUNICIPAL WRITER
DATELINE: LENGTH: Long
City officials say the ones who stayed must be cleaner, have shinier cars and prettier lawns. How else do you explain the fact that city residents are using millions more gallons of water each day than they did even five years ago?
Despite a drop in Roanoke's population in the past decade, the city's daily water usage has increased by 3.6 million gallons since 1980. On hot, dry days, the daily increase has been nearly 5 million gallons.
Businesses and industries account for part of the increased water usage, but they are not the main reason, said Kit Kiser, director of utilities and operations.
"We've gotten some new industries, but no major water users," Kiser said.
City officials aren't sure what caused the large jump in residential usage - the average residence is using about 33 percent more water than in the late 1970s, based on a computer analysis of city billing records.
But some think it might be related to residents' changing lifestyles: allowing showers to run longer, watering lawns and washing cars more often.
An average household is using 5,000 gallons a month, or 167 gallons a day; that's compared to 3,750 gallons monthly and 125 gallons daily about five years ago, according to statistics compiled by consulting engineers.
Roanoke's situation is not unique. Studies have shown that water usage has also increased in many cities, even those with stable or declining populations. But the trend in Roanoke has come at a time when its water-treatment facilities are operating near capacity.
The sharp rise in water usage is one reason the city says it needs to spend $28 million to expand the Carvins Cove filtration plant and make other improvements to its distribution system.
The city's population dropped from 100,200 to 96,397 during the 1980s, but the demand for water has continued to rise, particularly in the past five years.
In 1980, average daily use by Roanoke residents and businesses was 11.9 million gallons; that figure rose to 15.5 million gallons last year.
On so-called "maximum-demand days" when the most water is used, the increase was even more dramatic - from 16.7 million gallons in 1980 to 21.7 million gallons in 1990. These high-usage days are usually recorded during hot and dry periods in summer months.
The peak-hour demand by city customers also rose from 23.3 million to 30.3 million gallons in the past decade. This is the draw-down rate during morning and evening, when most people are at home and using water. Peak-hour demand refers to the amount of water that would be needed daily if customers used water at the same rate throughout the day as they do in the morning and evening.
Engineers recommend that water systems be designed to accommodate peak-hour usage so adequate water pressure can be maintained even when demand is the heaviest.
The city sells almost 3 million gallons a day to Roanoke County, but officials prepared separate figures for combined usage.
If the county sales are included, the average daily demand on the city water system since 1980 has increased from 15 million gallons to 18.6 million gallons. The figure on maximum-demand days rose from 18.4 million to 23.6 million gallons, which exceeded the city's rated capacity of 23.5 million gallons.
Kiser said the increase in the amount of water sold to the county has not grown as rapidly as city usage in recent years, partly because the county has developed more wells to help meet rising demand.
The city's water system includes three supplies:
Carvins Cove filtration plant, with an 18 million-gallons-a-day output capacity.
Crystal Spring reservoir, a natural spring without a filtration plant that can put out 3.5 million gallons.
The Falling Creek filtration plant, which can handle 2 million gallons a day. That plant will be out of operation until August, however, because it is being renovated.
The city has plenty of water in the Carvins Cove reservoir - a supply that will last 570 days - but its filtration plants are not large enough to meet the growing demand.
City Manager Robert Herbert said the demand exceeded the Carvins Cove plant's treatment capacity on 27 days in the past year and was at capacity 87 days.
Consulting engineers have recommended that the plant's daily capacity be increased to 28 million gallons.
They have predicted the average daily demand will reach 22.9 million gallons by the year 2010, and the maximum demand will reach 32.1 million gallons a day.
From a historical perspective, water usage has increased dramatically in the past four decades, even though the city's net population growth has been less than 6,000.
In 1950, when the city population was 91,921, residents and businesses used 7.5 million gallons a day, with a maximum demand of 9.5 million gallons. By 1970, when the population was 92,115, average daily use was 14.9 million gallons, with a maximum demand of 18 million gallons.
Usage fluctuated during the 1970s, after Roanoke stopped selling water to Vinton because the town developed its own supply. There were also unusual dry- and wet-weather conditions for several years during the period that affected water usage.
by CNB