Demand Threatens To Outstrip Chatham Water System Capacity

By: Alan Pollock

Topics: Drinking Water

Tap water

CHATHAM — Any recent wet weather aside, the town's water system is being taxed to its limits by this summer's drought. But even more importantly, it's feeling the pressure of increased demand year after year.

Last week, selectmen had an update from Water and Sewer Advisory Committee Chairman Larry Sampson, and heard again that the amount of water being pumped from the aquifer is increasing year to year. Board members are looking beyond strategies to get through the current dry spell and thinking about how to ensure a water supply that's adequate to meet the growing demand in the years ahead.

“We need to look forward to increasing production capacity,” Sampson said. With one well offline until an iron and manganese treatment plant is built, the town is short about one million gallons per day in pumping capacity this time of year, he said. Should another well go offline unexpectedly, “we would find ourselves in a difficult situation,” he said.

With the water supply just meeting peak demand, the town's water system has a safety margin of about 10 percent of total capacity.

“I don't think that that's a sufficient buffer,” Sampson said. A 20 or 25 percent reserve would be better, particularly since some of the additional capacity provided by the new treatment plant will be consumed by the time the plant is ready, he said.

During peak usage, the town's water tanks can only store enough to meet the demand for 12 to 15 hours, Sampson noted. Anticipating the need for additional storage capacity in the future, the water and sewer advisory commission has begun discussing the need for a consultant to study potential water rate increases to pay for those investments, he said.

The iron and manganese treatment plant and the town-wide installation of new “smart” water meters won't be complete before the spring of 2018, so – depending on the weather – Chatham can expect another summer when water demand threatens to outstrip the supply.

Officials say the problem isn't necessarily a lack of water, since the Cape has a large aquifer, but a lack of pumping capacity during times of peak demand. On Aug. 8, the town's pumps ran for 21 hours straight, far longer than engineers recommend. Operating the pumps for long stretches of time not only wears out equipment but also taxes the parts of the aquifer immediately around the wellheads.

The advisory committee has drafted revisions to the town's water regulations which would put many new controls on irrigation systems. Sampson said it's a logical place to toughen the rules.

“We're certainly not going to stop people from flushing the toilets” or bathing, he said. Restricting the use of town water for sprinkler systems might provide sufficient buffer “until such time as the treatment plant or additional wells are ready,” Sampson said.

The draft regulations would require that all irrigation systems connected to town water be placed on a separate water meter, installed at the customer's expense. The rule would apply to both new systems and existing ones. Irrigation systems would also be equipped with timers that allow the system to conform to various types of watering restriction schedules, as well as sensors that disable the system in times of rain or high soil moisture. Meters would be set to allow no more than one inch of water per week, and to operate only between 8 p.m. and 4 a.m.

Under the draft rules, customers who have a private well available for irrigation will be required to disconnect the sprinklers from town water by a specified date, and those with existing irrigation systems will be prohibited from adding additional sprinkler heads.

The good news, Sampson said, is that the growth in water demand decreased slightly in July. While consumption is still up over previous years, “it appears that people are taking hold to the concept of conserving water,” he said. In July, town wells pumped 99.1 million gallons, compared to 92 million last year, DPW Director Tom Temple reported. Though the growth in water demand decreased a bit, “it's still an 8.9 percent increase over the previous year's pumpage,” he said.

The increases aren't limited to times of peak demand, Temple noted. Comparing pumpage in May 2013 to May 2016, there was nearly a 21 percent jump.

“The increases are steadily going up,” he said.

Selectman Seth Taylor said the town knows how much water is being pumped from the ground, but doesn't know exactly where it's all going.

“It's a data management problem,” he said. A cursory inspection of water use by properties shows that some single-family homes have very large water bills, Taylor noted. Without a clear understanding of water use, it is premature to talk about raising water rates if “they're not part of the problem that we need to control,” he said.

Selectmen Chairman Jeffrey Dykens said the town needs to focus on both the supply and demand side of the problem. He said the town needs to study the techniques used by communities in places like Florida and Arizona to manage their water systems.

“I think it would behoove us to to reach out and find the best practices to manage water supply and demand,” he said.