Staff numbers have been boosted for Wrangell’s ailing water treatment plant this summer in an effort to keep up with increased demand.
Sedimentation has built up over the life of the 18-year-old plant’s slow sand filtration system, an increasing weight on efficiency, which last summer resulted in an emergency shortage of treated water. Measures to curb Wrangell’s usage were taken as a result, causing some disruption to the water-intensive seafood processors’ seasonal operations.
Public Works director Amber Al-Haddad explained the plant was poorly suited to Wrangell’s water supply from the start. Heavily sedimented water from its two reservoirs quickly clogged up the sand layer in the initial stage roughing filters, and periodically bungs up the silicate in the four main filtration bays. As designed, plant staff are supposed to skim and dispose of the topmost layer of the filters’ sand, replacing it with new material every few years.
The cost to replace the material has run into the hundreds of thousands of dollars – latest estimates put a full replacement of material at over $1,000,000 – which likely contributed to the decision to maintain rather than replace the sand. Over the years staff have thus had to modify and make do with the system as best as it could. Within its first year, Al-Haddad reported the roughing filter’s sand layer had to be replaced with stone to reduce clogging. Various methods to stir up and flush sediment from the main bays have also been employed over the years.
“Everything’s been modified, or else we’re cleaning it in an unconventional way,” Al-Haddad said.
Concerned about the plant’s ability to perform this year, last month in a special meeting the Borough Assembly approved replacement of the roughing filter with a more recommended model that automatically flushes, as well as new sand for one of the bays. It reversed course on the latter option at a subsequent meeting when it learned the new material would not be delivered in time for the coming summer.
Instead, Assembly members instructed Public Works to take on additional staff devoted to keeping the filters clear over the summer, when water usage is at its highest. Higher usage means faster filtration, and the additional sedimentation build-up that brings. As such, the three-person staff employed to run both the water treatment and sewage treatment plants have in the past been pushed to their limits trying to keep up.
“We have hired four temporary employees,” said Al-Haddad. The hires are all local, and are full time. One has been hired for the whole summer, with the others for four to six weeks. “They’re already up there working.”
Replacing the previous “harrowing disc” method of clearing sediment, which involved partially submerging an ATV in the filter bays, the new method to clear up clogs staff will be using has been referred to as “plunging.” Al-Haddad explained a manifold with four hoses tipped with copper wands injects a mixture of water and air deep into the filters’ sand. “As they push it what it releases the air and the water pushes up the sand, and brings particulates that have attached to the sand up with it.” This material is then freed up and removed from the units.
“They are working daily,” she continued, working through each filter and the roughers at least once a week. The method is a unique approach to a unique problem, but Al-Haddad expressed optimism in it.
To better measure how well it actually works, though, a meter has been added to one of the plant’s effluent lines. Previously there has been no built-in way to measure output from the plant’s filters, and so gauge their relative efficiency or compare it to past years.
“We’ll be giving some averages and comparisons,” she said, as the season progresses.
Otherwise, concerns in February that water levels at the reservoirs were low following unusually high usage over the winter have reversed, following melt-off and a good rainfall.
Both reservoirs are full, with the upper one actually overflowing. The plant’s two reserve tanks for treated water, together holding around 820,000 gallons, are also filled to the top.
“We are still encouraging people to start finding ways to routinely save water,” Al-Haddad added. This means finding alternative sources of water, such as rainwater, for gardening and lawn care, and being more conservative or mindful of usage. People are asked to check for leaks as well.
A public outreach program will also be employed, with color-coded signage outside City Hall letting people know how water conditions are on a blue, yellow, orange and red scale.
“If it’s blue, we’re good,” the Public Works director said.
Additionally, the city will keep people updated through social media, newspaper and the radio, as well as its website.
The application process seeking funding for a new, better-suited water plant is being navigated through the help of the Department of Agriculture. Right now the city’s finances are being examined in order to weigh its ability to pay for loans against its need for grants for the project. A new plant could cost $8.5 million.
Reader Comments(0)