The Great Salt Bay Sanitary District operates two distinct wastewater systems – one for the vast majority of its customers in the Twin Villages; another to serve 53 homes in Damariscotta Mills.
The path of wastewater starts in the homes and businesses the district serves every time someone drains a bathtub, empties a sink, or flushes a toilet.
The users of the larger system produce approximately 150,000 gallons of wastewater every day.
The wastewater travels through the district’s sewer lines and into one of seven pump stations scattered around Damariscotta. Ultimately, all the pump stations re-route their contents to the Day’s Cove pump station on Miles Street.
The Day’s Cove station, in turn, pumps the sewage up High Street to the wastewater treatment plant on Piper Mill Road. The foul-smelling soup flows through a bar screen (a grid preventing various foreign objects from entering the lagoon) and a grit channel (where more solids settle) and into a four million gallon, man-made lagoon, the first and biggest in a series of three.
The lagoon system “works the same way your septic system does,” Great Salt Bay Sanitary District (GSBSD) Wastewater Division Manager LeeAnna Hutchings said during an Aug. 10 tour of the facility.
The sole difference is that the lagoon system is aerobic (it requires oxygen) while a typical septic system is anaerobic.
The wastewater slowly travels through the three lagoons, where insects feast on sludge and aerators on the lagoon floors supply oxygen. Upon exiting the final lagoon, the wastewater enters a chlorine contact chamber, which disinfects the wastewater.
Finally, the wastewater is pumped into the Damariscotta River via a pipe about 100-150 feet from the end of the town landing.
Imhoff cones in the district laboratory illustrate the change in the wastewater from the time it enters the lagoon system (influent) until it exits on its way to the river (effluent).
The influent is opaque and a small percentage of semi-solid waste (sludge) settles to the base of the cone. The substance draws a stark contrast with the clear, sludge-free effluent, which might easily be mistaken for potable water if not for the tiny, green daphnia, or water fleas, swimming inside.
Sometimes “we have so many they look like pepper in there,” Hutchings said.
“Someone told me a good operator will drink their effluent,” she said. “Not me.”
The daphnia, while unappetizing, perform an important function.
The tiny crustaceans – not insects, despite the “water flea” moniker – eat algae, which can turn into “a real problem” otherwise.
The entire process, from the time a GSBSD customer flushes his or her toilet until the effluent reaches the river, takes about a month to 45 days.
There are no individual septic tanks on the lagoon system. Damariscotta Mills customers, however, use septic tanks which the district maintains.
The Damariscotta Mills sewer lines carry gray water from the tanks to four pump stations and, eventually, to a sand filtration system on Depot Street.
The water, after filtration and disinfection, is pumped into Great Salt Bay.
A contractor periodically empties sludge from the Damariscotta Mills septic tanks at a septic disposal site near district headquarters on Piper Mill Road.
GSBSD employees screen the contents of the tanks and spread them at the site (a field near the lagoon), using lime to kill pathogens and fertilize the waste.
“It’ll smell for an hour or so,” Hutchings said. “The lime takes care of that.”
Hutchings’ association with the district began in 1986, when she worked as a laborer for the contractor building the wastewater treatment plant.
The district needed someone to help operate the plant. “I applied for it and they hired me,” Hutchings said.
Today, the wastewater division is facing a number of challenges. About 200,000 gallons of sludge have collected in the first lagoon. GSBSD must decide whether to hire a contractor to remove the sludge or install a treatment tank to compost the sludge on or off-site.
The district must remove the sludge periodically and, for the first time since the plant’s construction, it did around 2002-2003.
Elsewhere, an important sewer line under the municipal parking lot “has a few sags in it,” Hutchings said.
In the old days, wastewater from several buildings downtown flowed directly into the river. The district capped all the old pipes, re-routing the sewage to the lagoons. The old pipes, too – some of which are made of clay tile instead of PVC, like modern pipes – are in need of replacement, which further complicates matters, as the ownership of the old plumbing is often unclear.
The Town of Damariscotta is in the process of engineering major repairs to the parking lot, and the district wants to cooperate with the town to coordinate the projects and avoid tearing up the asphalt more than once.
District employees also deal with customers flushing a wide variety of inappropriate items, leading Hutchings to enclose a reminder in a recent bill.
The list of unwelcome objects includes baby/disinfecting wipes, disposable toilet cleaning pads, moist towelettes, makeup removal pads, disposable mop heads, dental floss and surface cleaning wipes.
“While many of these products are marketed as ‘flushable,’ several studies (and the experience of homeowners and utilities across the country) have shown that they do not break down after disposal like common toilet tissue,” Hutchings wrote. “The synthetic fibers that make the wipes and other products strong and effective can cause them to form clumps that easily entangle in pipes and pumps without ripping.”
The district hopes the potential consequences of disregarding the notice will cause consumers to take heed. “Sewage can back up behind these clogs, sometimes causing wastewater to discharge into homeowner basements or overflow pipes into surface waters,” Hutchings warned.
Preventing blockages, in addition to avoiding personal inconvenience, will “minimize additional work for our staff” and “protect not only your local surface waters but your bottom line by reducing the need for rate increases to fund expanding maintenance requirements,” Hutchings wrote.
The items, supposedly “flushable” or not, should go in the trash, along with “disposable” items like diapers, feminine hygiene products, plastic gloves, bags and cloths.
Hutchings adds pet fish and prescription medications, which are “starting to interrupt the reproductive systems of aquatic animals,” to the list.
For more information about proper disposal of prescription medications, which shouldn’t go in the trash, call (866) ME-RX-RID or visit http://www.safemeddisposal.com.
For more information about what not to flush, or to schedule a tour of the facility, call LeeAnna Hutchings at 563-5105.
