Wrangell’s utility users were advised last week to start being more conservative with their water usage, with the city going into the first phase of its emergency response plan.
The plant which has treated the city’s municipal water supply for most of the past two decades has in recent years been having trouble keeping up with peak demand, which locally is during the summer. Ongoing problems with the aging facility came to a head last year, with a shortage prompting a declaration of disaster by the mayor in July and emergency conservation measures disrupting service into August.
The crisis was new territory for the Borough Assembly, which has since adopted a formal emergency response plan, codified this April. The color-coded, three-phase plan – yellow, orange and red, by increasing severity – was intended to better coordinate departments and the public when responding to hydrologic or emergency shortages to the water supply.
Normal conditions pervaded heading into the summer, which yearly sees increased activity. In addition to the two seafood processors stepping up their production, upped usage by residents and other seasonal enterprises together puts strain on the water treatment plant’s ability to keep up with demand.
Increased and prolonged draws from the plant’s treated water storage supply have caused those reserves to begin fluctuating. The usable capacity of its two water storage tanks is together approximately 850,000 gallons, or at tank levels of 32 feet. A minimum of 10 feet of storage is the city’s minimum level for fire protection, and so is the threshold for the most severe emergency stage.
The yellow Stage I order was issued by the city manager’s office last week as a precautionary measure.
“We were seeing the level start to drop and were just trying to be cautious,” explained Public Works director Amber Al-Haddad.
“Our reservoirs are both fairly full,” she added. Wrangell’s plant draws its water from two reservoirs, with an upper one feeding a lower, from which water is pumped. The maximum capacity for them is 45,300,000 gallons and 21,400,000 gallons, respectively. Those reserves pose no problem for the present in themselves, with levels helped by several weeks of rainfall.
With that rainfall, however, water quality decreases as sediment and organics are added to the pool, which in turn lowers plant efficiency by collecting in and clogging its filters. The plant has two sets of filters for treatment, with a preliminary roughing filter preparing water for slow sand filtration. Four filter bays together filter through the city’s water, which is also chemically treated before heading to the storage tanks.
Over the life of the plant facility, the sand in the filtration bays has never been replaced as designed. Cost was a primary factor for this, with estimates this spring placing costs to replace the material at just over $1,000,000. Instead, city staff have taken different measures to clear and skim material from the bays, processes which have varied in efficiency and are resource- and time-consuming to undertake.
One filtration unit can take 15 or 16 hours to take offline, clean and bring back into service, in the meantime reducing overall production by a quarter. This can be substantial, as over the past month the plant has been producing around a million gallons of treated water per day. During the week of June 19, the daily average was at 1,045,857 gallons; the following week it was at 962,000.
Last year a combination of mechanical, staffing and water quality factors had contributed to the summer shortage. New measures have since been taken to head a repeat performance off at the pass. This spring the Assembly approved temporarily taking on four additional staff to assist with operations. Year-round, Public Works employs three technicians for both its water and sewage treatment, with one dedicated to each processing plant and the third splitting duties between them.
The workers together went with a new method of flushing the filters, which Al-Haddad has credited with improving performance the past three months.
“We have been able to keep up really well,” she said.
The invigorated cleansing had increased the filters’ useful life to three weeks between cleanings, Al-Haddad reported. Even with the step up in demand, filter units are still getting between two and three weeks of use before being taken offline for cleaning, rather than several days during last summer’s emergency. This means the plant is spending more of its time running at full production, rather than at a hobbled rate.
“If they’re running and none of them have to be cleaned, they’re all producing,” she noted.
This means they are better able to keep up reserves in the plant’s storage tanks, which are generally drawn down each day. From the storage units, during daytime hours between 800 and 900 gallons flow into town per minute. Al-Haddad noted this drops off substantially during the evening, during which time the plant has time to refill the tanks.
Thinking conservatively
The conservation stage declared last week is the first of three response levels approved by the Assembly in April. Stage I is a more cautionary response, triggered when tanks drop to 25 feet for a period of three days. At this point, the city increases its communication with the public and begins to implement different conservation measures.
Water landscaped areas with spray irrigation are limited to the hours between 5 and 8 a.m., and use of water to clean outdoor surfaces like sidewalks, driveways, decks and patios, or vehicles, trailers and boats are discouraged. To keep people conscious, restaurants are asked not to automatically serve water to patrons, except by request.
Major industrial and commercial water customers using water for their business operations are required to submit a water conservation plan to city staff, implementing the first of its three-stage response measures. These customers include seafood processing plants, dock-fueling stations, and ports and harbor facilities. Also during Stage I, commercial
water sales to cruise ships and other large purchasers for
use outside of the water enterprise fund service area are prohibited.
Fines begin to be implemented in the higher stages, when sustained tank levels reach 20 feet for Stage II or 15 feet for Stage III. Further limitations on use are imposed with each step, with the threat of water shutoff hanging over those not in compliance. Any flow restrictions put into effect remain so for a period determined by the city, based upon the severity of the violation as well as the applicable declared stage.
Signs denoting the current water alert stage are posted outside City Hall, the post office, and other public locations. Information is also kept up to date on the borough website, and a full list of stages and restrictions are available at http://www.wrangell.com/sites/default/files/fileattachments/public_works/page/6021/wrangell_water_shortage_management_plan_-_final.pdf.
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