June 21st Update: Town Meeting approved the funding request. Construction is expected to begin in August 2017.
The Board of Selectmen has scheduled a Special Town Meeting for June 20th so the Town can consider funding the water treatment plant project. Bids were opened on May 31st. Based on the bid results the construction funding request will be for $10.4 million. Funding will be sourced from multiple areas including $800,000 from Water Department retained earnings, $350,000 from existing Water Department warrant articles, and a $9.25 million borrowing authorization. This funding is independent of the tax rate and will be covered water rates and fees.
The treatment plant is very similar to what was envisioned when the Town appropriated design funding in May 2014. Some changes were made from the original plan outlined in 2014, most of which involve the addition of an aeration process. Aeration will be used to remove carbon dioxide from our water, reducing the water's acidity and improving our corrosion control treatment. We have used pH adjustment as the primary corrosion control method and have been in compliance with EPA's Lead and Copper rule for many years. EPA amended their corrosion control guidelines a few years ago and aeration is needed to meet them. The result will be a more robust corrosion control system that will lower lead and copper levels in tap water.
Adding the aeration step created additional head losses in the plant and our existing pumps are not sized properly to push water from the stations through the plant's treatment systems. An equalization basin was added to the plant so that our existing pumps could pump water to the plant and low lift pumps in the plant will pump the water through the filters and aerator. The aerator also requires the use of sequestrant to keep minerals from precipitating out of solution inside the aerator.
The treatment plant will completely change the quality of our water for the better. The benefits include:
- Removal of manganese - Pilot testing has shown that the greensand filters will remove virtually all of the manganese from the raw water. This means water discoloration seen during main breaks, hydrant flushing, etc. will dissipate over time. Sediment already in the distribution system will have to be flushed out but water quality should drastically improve.
- Improved corrosion control - We have been in compliance with corrosion control regulations for over 20 years. However, this means that 90% of our samples are below action levels set by the EPA. We typically sample 20 pre-approved sample sites per year. Almost every year one of the sites tests over the action level, which is allowed when you take 20 samples as 10% can exceed the limit. Our hope is that all of the samples will be below the action level with the new system.
- Ground Water Rule Compliance - A number of years ago the EPA promulgated this rule to regulate systems like ours that use groundwater. The rule has a series of phases triggered by finding certain types of bacteria in the treated water. We have not had any bacteria hits so we are in compliance. If this rule were to be triggered, it would require a minimum amount of time the disinfectant would be in contact with the water before reaching the first customer's tap. The plant is designed to meet these requirements if necessary.
- Lower chlorine levels - Chlorine reacts with manganese and the reaction can take several days to complete. Currently we have to add enough chlorine to compensate for the demand created by the manganese reactions so chlorine levels tend to be much higher near the water sources. Removing the manganese and providing disinfection contact time before the water leaves the plant will allow lower and more stable chlorine levels in the distribution system.
The treatment plant project will cost the average customer an additional $1.22 per day or $443 per year based on FY2017 rates. This is simply the expected cost increase of the plant divided by the number of customers compared to the FY2017 budget. Actual costs incurred by customers will depend on a variety of factors including how much water they use, the rate structure, the borrowing interest rate and the type of repayment schedule. The rate estimate is based on the average water use, the current rate structure continuing, a 5% interest rate and an aggressive repayment schedule.