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WAPA’s Water Distribution System Update

(Friday, March 14, 2014)

In 1981, the Virgin Islands Water and Power Authority (WAPA) constructed and began full operation of Israel Desalination Engineering (IDE) water plants. IDE water production was solely dependent on fuel driven steam production sources.

In June 1987, the responsibility of distributing potable water was transferred from the Department of Public Works to WAPA under Act 5265. With this transfer, WAPA inherited the water distribution system that was primarily comprised of cast iron pipes that were installed as early as in the 1930s. At that time, in an effort to protect the aging and integrity of the distribution’s piping, an approved National Sanitation Federation (NSF) corrosion control additive, which is common in such instances, was injected into the system.

In December 2011, WAPA was forced to ration potable water distribution in the St. Thomas/St. John District due to failures on the steam production resources at the Randolph Harley Power Plant. During this period of rationing, the aged cast iron distribution pipes in the system were without constant water flow, making them vulnerable to corrosive elements. This abnormal situation caused a compromise to the corrosion control treatment process throughout the system, which would not have occurred with normal operations.

In response to the water rationing, WAPA immediately commenced the production of potable water with a combination of sources, namely reverse osmosis and IDE. At that time, WAPA resumed its normal corrosion treatment application of the distribution system.

In 2013, Seven Seas Water was contracted to fully supply the District’s potable water needs via a seawater reverse osmosis (SWRO) process. This transition relieved the production of potable water from its dependency on fuel driven steam production sources.

This sudden change in chemistry from IDE to SWRO potable water caused a slight unstable condition in the distribution system. This unstable condition caused some deterioration in the aged piping system, which produced iron sediments creating what is now termed as “colored water” in isolated pockets of the system. The areas observed with this condition are Contant, Garden Street, Bunker Hill, Altona and Old Tutu. These impacted areas are serviced via aged cast iron piping and are on “dead end” points, meaning that water conditions are stagnant or limited in use.

Being cognizant of this condition, WAPA has tasked its water quality personnel to closely monitor the conditions of the distribution system and the noted sites on a daily basis. WAPA’s water quality laboratory operates under federal and local primary drinking water standards and requirements for monitoring bacterial and chemical contaminants in potable water, and must certify that these sources are compliant with applicable federal and local primary drinking water standards. Federal drinking water regulations consider “colored water” caused by iron sedimentation a secondary standard, and is only required to perform testing on a voluntary basis, which is being done by WAPA routinely. Additionally,

WAPA, after an internal comprehensive assessment supported with outside consultation of the colored water issue, recently changed its corrosion treatment to an additive more suitable for the chemistry of the SWRO produced water. This additive is an NSF approved treatment for drinking water and is recognized for effective control of lead, copper and corrosion levels in water distribution systems. WAPA has also implemented an aggressive flushing program to provide near term relief to impacted areas. Flushing allows for the corrosion control treatment to rapidly move throughout the water distribution system, which ultimately will improve the colored condition being observed by customers from time to time. Overall, WAPA’s efforts and observations indicate continuous improvement in the “colored water”.

While the presence of “colored water” may cause some alarm to customers it is more of a cosmetic issue and is safe for human use once all primary standards are met, as in this instance. Further, WAPA has embarked on a mission to fully assess the entire distribution piping system and, as funding becomes available, will replace its aged cast iron distribution pipes with a priority structure to address known areas of concern.

Despite all efforts undertaken, replacement of the aged cast iron piping in the distribution system is the ultimate solution to the “colored water” being observed from time to time in limited areas.

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