Bristol sewer proposal calls for double capacity

August 16, 2007
BRISTOL — The Bristol selectboard on Monday received a proposal for a new wastewater treatment system to fix the town’s lack of excess sewage capacity. If the plan is approved in its current form it would double the existing capacity of the system, which is now at its limit and cannot allow additional users or changes in use.
The proposal presented to the board by engineer Alan Huizenga is only a draft, preliminary proposal, he said, and would cost between $400,000 and $500,000. The proposal would be voted on by residents before any action is taken.
“This is the first step in the preliminary design process,” said town administrator Bill Bryant.
Huizenga presented several options to the board, all of which would fit in the existing space on Basin Street now used as a septic tank for the roughly 30 members of the downtown sewer district. Huizenga’s analysis ultimately recommended a system called Cromaglass, which retains solid waste in fiberglass tanks and breaks the waste down by aerating it. It would then pump it into a settling chamber and from there into the municipal system’s leach field.
In the Cromaglass design, air is vented in from above ground, but no venting back out of the chamber would be needed, so little or no odor would be generated, Huizenga said.
The location itself was a limiting factor in designing a system, he said. Huizenga presented the board with some other options that were not recommended for various reasons. For some products, getting concrete tanks or similar hardware down the narrow, steep road to the Basin Street location would also be an obstacle.
In addition to the cost of installing and starting the system, all alternatives Huizenga presented would increase the annual operating cost of Bristol’s wastewater system, because the system now runs on a gravity feed, but any kind of processing would require electric power.
Huizenga estimated that the system would generate about $11,500 per year in electric bills if it were running at full capacity. However, that capacity is about twice the current use of the field, so it would probably not reach that level immediately. The current operating budget of the wastewater system is now about $17,225.
“By the time you’re done, you’re probably going to double your sewer budget,” Bryant said.
Huizenga began working on plans for the system last fall, when the septic system’s capacity reached its limit. The current treatment facility was constructed in 1993 to replace the individual systems of the downtown property and business owners.
The current system has a design capacity of 20,000 gallons per day, but there are more constraints than simply the volume of the flow. Actual flows have been much lower — between April 2005 and March 2007, the average daily flow was 8,226 gallons per day — but the wastewater generated by Bristol’s downtown is of a higher concentration than usual. According to officials, it is about double what the system was designed for.
“Your permit says you can discharge 20,000 gallons a day, but you really can’t because the concentration is so high,” Huizenga said. He explained the higher concentration of the wastewater might be because so many of the downtown businesses were restaurants rather than offices or private homes.
The amount of reserve capacity remaining had been steadily dropping as new businesses were added or existing ones expanded until last summer. Three new applications for use came in a short period, a rare burst of activity according to then town clerk Penny Sherwood. Not all of those permits were granted, but the town was bumping up against the limit.
In May, the wastewater management division of the state determined that the available reserve capacity was 1,442 gallons per day, which Huizenga said was not enough for a 50-seat restaurant or six two-bedroom apartments.
“A couple hundred gallons isn’t a lot of wastewater,” he said.
Huizenga said that the proposed system could be completed as early as October 2008, but only if all votes and plans are made on an aggressive schedule. 
Bryant said that the current system has been generating a surplus in fees paid to the town by business owners to use it. But at only about $1,000 to $5,000 per year, he said that money would not be enough to support the increased annual operating costs.
The electric bill would be the lion’s share of the increase, however: Huizenga said that once the kinks are worked out, the new system would require no more maintenance than the current one.
How the town would pay for the change is an open question. Bryant said they would seek grants, but would likely have to pay for most of the project with a bond.
Bryant said the town needs to make changes to its wastewater system, but was unsure what those would be.
“The sewer has been very important to revitalizing the downtown area, and we don’t want to lose that,” Bryant said. “The selectboard’s going to have to do some careful weighing of those issues.”

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