ORLEANS — Even as contractors are digging into downtown streets to install sewer pipes and excavating the foundation for a wastewater treatment facility, town officials are digging into the details of the second phase of the massive project: designing and building a collection system to remove all the nitrogen in Meetinghouse Pond.
The town is under a mandate to reach a Total Maximum Daily Load of zero in the pond for nitrogen, which decreases water quality while encouraging algae blooms. The major source of nitrogen is entering groundwater through the area’s septic systems.
In June, town meeting voted $1,700,500 for a utility survey and preliminary design work for Meetinghouse Pond Area Wastewater Facilities and further exploration, town-wide, of nitrogen-altering permeable reactive barriers. Final design funds will be sought at next May’s town meeting, with construction dollars on the agenda in May of 2022.
These and other water quality matters were discussed by the select board, the board of water and sewer commissioners, and town consultants Dec. 2. Tom Parece, senior program director of AECOM, said the Meetinghouse Pond Area system would serve about 474 users, less than half of those on the downtown collection system. Given the pond area’s varied topography, about half of those users would need privately owned and maintained low-pressure sewerage pump systems to send their waste into the collection system. All users would need to pay for the connection from the sewer to their properties.
That arrangement reflects the consensus plan worked out by a variety of town groups who studied the community’s wastewater needs, heard from the experts and reached conclusions. It does not encompass a possible extension to properties near Uncle Harvey’s Pond, which has suffered from high levels of pollutants. A planned alum treatment is working its way through the permitting process, but that does not resolve the continuing problem of septic systems that discharge into the water body.
Parece prepared two sets of very preliminary numbers to show the difference connecting 179 more users to the Meetinghouse Pond Area sewer would make. Without Uncle Harvey’s Pond included and with anticipated funding source reductions, the probable cost per property would be $25,450; with Uncle Harvey’s the higher number of users would reduce the per property cost to $23,357. Parece noted that those amounts do not include the cost of installing piping from the property to the system, which would be borne by the property owner. Also, that number does not include the amount that about half of the users would have to pay for a booster pump.
“$25,000 is always a shocking figure to see,” select board member Mefford Runyon said. “The reality is that this is a betterment. It would be nice to pick some average duration, 20 years or 30 years, to give an idea what the annual cost is… If they sell the house after five years, the subsequent buyer will be standing in their shoes. Saying that everybody has to pay that is unnecessarily alarming.”
Other areas for potential expansion include properties near Crystal and Pilgrim lakes. These would require further discussion and approval from the water and sewer and select boards before moving forward.
The three-year experiment with nitrogen-altering, below-grade, permeable reactive barriers off Eldredge Park Way “continues to see very favorable results,” Parece said. At a presentation to the state Department of Environmental Protection in May, “they were very positive as far as being able to use PRBs as one of the items in the toolbox to remove nitrogen from water bodies.”
Preliminary design work is under way regarding using PRBs in about 34,000 linear feet of the Pleasant Bay, Nauset, and Rock Harbor estuaries, “following existing roadways and not going into people’s backyards,” said Parece. Early results from a life cycle cost analysis vary. “Some PRBs show absolutely cost-effective for the whole 100 years,” Parece said. “Others show sewer as more cost-effective, and some flip-flop… There may be opportunities to put PRBs in now and, when some debt is paid off, (it) may make more sense to put sewering in at that time.” Money approved at the June town meeting will allow AECOM “to fine-tune our assumptions,” the engineer said, by “drilling some holes in the ground and getting a better handle on the depth of groundwater, the amount of nitrogen in the ground, and groundwater flow.”
The balance between methods is tricky. “If you put PRBs in, you end up getting a quicker response for cleaning up the environment by treating the nitrogen already in the ground,” said Parece. “At the same time, on-site systems are still contributing that nitrogen to the groundwater. If you put sewer in to stop those properties, it’s already in the groundwater and will continue to go toward the water body. There’s not just an economics viewpoint but an environmental viewpoint.” He said nitrogen flowing through the middle school property, where PRBs are now in place, will take 40 to 60 years to reach Town Cove.
“This is the first time we’ve had any discussion, in public anyway, about your projections of PRBs versus sewers over a 30- or 60-year period,” select board member Mark Mathison said. “If we were to change the town’s regulations so that all new construction and all replacements of Title 5 (septic) systems had to be alternative systems that don’t reduce nitrogen to zero but greatly reduce nitrogen, would that be something we could look at that would increase the longevity of the PRBs and significantly impact the reduction of nitrogen going into these places? We’re going to a sewer system to remove 100 percent (of nitrogen) from Meetinghouse Pond, but what if we didn’t have that 100 percent mandate but had a way to eliminate a vast amount by a combination of PRBs and maybe alternative systems?”
Parece said that innovative/alternative systems on individual properties can cut nitrogen levels coming from households by half, (but) “PRBs have shown they can drastically reduce (nitrogen) to near zero in a lot of cases…. If you reduce the amount coming into (the groundwater), the PRB doesn’t have to work as hard, or will last longer. That comes with a downside: you’re now requiring property owners to put in a much more expensive on-site system.”
“With the amount of building and rebuilding and demolition,” Mathison said, “over those 30 to 60 years, people would be replacing systems anyway. I think this is something we should be looking [at]. Trying (eventually) to run sewer lines down to South Orleans and get back to the treatment plant would make the cost, I would think, extremely prohibitive.”
Water and sewer commissioners vice chair Alan McClennen had yet another angle to add. “Let’s remember our Pleasant Bay Alliance is working on an update to the information on the total maximum daily loads of every watershed,” he said. “We have TMDLs that have been set by the federal government to tell us how much nitrogen has to be removed… Our Pleasant Bay Alliance and others are working together to make sure the numbers in the TMDLs are correct. When that work is finished, it will help us understand which technologies will be appropriate to use in our area to meet the federally-mandated TMDL.”