NORTH ANDOVER — The amount of sewage produced by Royal Crest Estates could double if current plans for the property’s redevelopment are eventually approved at Town Meeting.
Redevelopment plans mean the number of people who live and work at the 77-acre site across from Merrimack College on Route 114 would increase substantially, as the number of units there grows from 588 to 1,309.
Those numbers come from Boston-based developer Trinity Financial, which hopes to demolish the purely residential units that have occupied the property since the early 1970s, and replace them with a combination of retail, business and office spaces.
But the figures don’t tell the whole story, as representatives of the developer explained at a Planning Board meeting in September, when the topic of utilities at the project was discussed.
Jeffrey Koetteritz, an engineer working for Trinity Financial, told the board that the Greater Lawrence Sanitary District, which treats the region’s wastewater, was not bothered by the fact that Trinity’s plans projected an increase in Royal Crest’s sewage from 140,000 gallons per day to 300,000.
“We did present that estimated daily increase in flows, and they confirmed that that was not a concern as far as their treatment rates at the plant,” he said.
What does remain a concern, as Planning Board member Peter Boynton suggested at the meeting, is whether the increased sewage would contribute to Combined Sewer Overflows, which occur when excess rainwater overwhelms the town’s sewers, causing them to dump raw sewage into the Merrimack River.
The possibility of that happening is enhanced by the fact that groundwater at the site is high, and can easily seep into clay pipes that currently carry the sewage.
Adding lots of rainwater into that mix could contribute to the likelihood of CSOs, which is why Trinity has several fixes in mind for Royal Crest’s sewers.
“It would be a water-tight system,” Koetteritz said. “We’d be replacing the clay pipe with PVC. We’d waterproof the manholes and connections with ‘rubber boots’ so we would be eliminating any opportunities for storm water to get into that sewer system associated with our site.”
Reducing the amount of water that seeps into the pipes and mixes with sewage during normal weather would also help reduce the amount of sewage that typically flows from the site, Koetteritz said.
Other measures that reduce the amount of storm water making it to sewers could include building large, concrete chambers underground that detain water during storms, until it can be safely released.
Trinity’s plans, which can be viewed at the town’s website, also include constructing wetlands and rain gardens. The latter are depressions in the ground filled with plants, and both measures retain water.
“We are getting creative with management of the storm water in particular because there is a lot of it on this site,” said Mike Lozano, a vice president at Trinity Financial.
In addition, contrasting the current number of units at Royal Crest with those called for in Trinity’s plans doesn’t necessarily reflect the number of people who will be using water, electricity and other utilities at the site, Lozano said.
“All of the units that exist there today are two and three bedrooms,” he said. “The majority of the units that we’ll be introducing to the site are one bedroom units.”
Trinity also plans to use low-flow technologies throughout the site, which would limit the amount of water that is used by residents, then ends up in the town’s sewers. No such measures are currently in place at Royal Crest.
Board member Alissa Koenig asked whether changing to low-flow technology meant that, even if the population at the site doubles, the amount of sewage would not necessarily double along with it, and Lozano said that was correct.
“We expect to do better than what is presented, but we have to give you a worst case scenario,” he said. “We have to plan for a worst case scenario.”