Tisbury selectmen met with environmental consultants Tuesday to discuss the current status of the wastewater treatment plant, and to plan for possible changes in the future.
Mark White, principal and co-founder of the Environmental Partners Group, described his conversations with the sewer advisory board regarding permitted flows versus available capacity.
Currently, White said, the treatment plant is at a 104,000-gallon-per-day permitted flow threshold. With the committed flows and existing usage, White said the treatment plant is “pretty much at capacity.”
“Some people have paid their betterments, but are not yet connected to the system. We also have to allocate for town septage, and pumpout from the Steamship Authority,” White said.
He explained how these additional uses are not currently factored into the overall inflow equation, but they would need to be taken into account should the town plan for any changes to the system. “When you add all those factors up, you are right there at the flow limit,” White said.
In 2013, White said the town performed an evaluation of the treatment plan to see how much additional capacity could be created within the existing system.
According to White, with minor modifications to increase efficiency, the maximum flow capacity could be increased to over 140,000 gallons per day.
“If you want to squeeze all you can out of the current plant, you would need to maximize all the treatment processes,” White said. “Eventually you would reach the maximum hydraulic capacity that system can handle.”
Currently, White said, upgrades to the treatment plan are in the works to bring capacity up to the maximum allowed flow with the permit the town currently holds. “We are looking to bring the plant out of the 20th century and into the 21st century, with modern technology that will make the process more efficient,” White said.
White said this would include putting in new headworks, and installing advanced electronic systems to monitor flow levels.
If the town were to start accepting more wastewater flow into the treatment facility, White said effluent disposal would be the next practical consideration.
He suggested looking at existing effluent beds to see if the permitted discharge infiltration rate could be increased.
After demonstrating to the Department of Environmental Protection (DEP) that the effluent beds could indeed handle additional capacity, the DEP authorized the town to increase the daily flow to 140,000, but the town would need to modify its discharge permit.
Another issue the town is dealing with regarding wastewater is the newly established State Road sewer district, to which the town must allocate a certain percentage of flow.
There are 67 properties in the district, according to Melinda Loberg, chair of the board of selectmen. Along with the properties located within the State Road district, the town must also allocate additional capacity for anticipated needs, including additional affordable housing, changes in municipal flow, and other elements.
This would, according to White, constitute an increase in flow that would meet or exceed the projected 140,000-gallon capacity.
“There hasn’t been a comprehensive study, but we put in some planning levels to look ahead a bit, and it’s easy to get over 50,000 gallons a day just from those needs,” White said. “So do we expand the plant? What do we do to plan for the future? This is a question for the selectmen.”
Loberg brought up the issue of increased nitrification in Tashmoo and Lagoon Pond, causing loss of eelgrass and problems with fish and shellfish.
She said the State Road district was initially created to draw wastewater away from private tanks that would normally go through the groundwater and end up in Tashmoo.
“We need to figure out how to deal with our wastewater demands — both our health ones and our environmental ones,” Loberg said.
She mentioned the comprehensive wastewater planning document that the town is working on drafting. “That plan calls for a lot of public input, and ties in well with the possible modifications to this plant,” Loberg said.
Selectman Jeff Kristal said he would like to see the board work toward performing a cost analysis for possible expansion of the facility itself. “We are going to need that extra capacity down the road, so I really think we should start now,” Kristal said.
Tisbury wastewater facilities manager Dave Thompson said, “If you are going to think, think big.”
He suggested looking further into the future to plan for expansion of the treatment facility and necessary infrastructure changes. “You may run into some resistance at first, but 20 years down the road, everyone’s property values will increase because they will have enough sewer, they won’t feel constrained if they want to grow their property,” White said. “You can look four or five years down the road, but you really need to look further down the line, because that’s when any expansion will pay for itself.”
Tisbury will drag its feet on this like it has on all the other issues that have come before the town and will cost money. Do the correct thing and allocate some funds to bring the treatment plant into the 21st century. It will only cost more later on. Pay me now or pay me later.