The Edgartown wastewater treatment facility has dramatically curtailed its capacity for taking pumpouts from septic systems in recent months, forcing septic haulers to scramble and potentially reordering the Island’s patchworked wastewater treatment system.

Town officials described the change in policy as a necessary shift for the overburdened Edgartown treatment plant, which is by far the largest on the Island and for the past decade has informally accepted almost an entire Island’s worth of septic system pumpouts.

The town recently retained an engineering firm to conduct a cost-benefit analysis on capacity at the treatment facility before making any further, permanent policy changes.

But the current change — which severely limits what the facility will accept from outside haulers to emergency pumpouts from failed septic systems, tight tanks and porta-toilets — has already caused reverberations throughout the Island.

Septic haulers — their pumpout trucks known colloquially as honey wagons — say they have had to cut their business approximately in half, forcing them to make plans to either temporarily store excess septage in new holding tanks or transfer the waste to off-Island facilities.

The Oak Bluffs treatment plant does not accept septage pumpouts, and the Tisbury plant only accepts a small daily amount.

Only the three down-Island towns have municipal sewer systems; approximately 90 per cent of the Vineyard’s built environment relies on individual on-site septic systems for human waste disposal.

The changes at the Edgartown plant mean non-emergency septic system pumpouts for residences and restaurants are mostly on hold. Although on-site septic systems provide an efficient filtering and treatment process, routine maintenance through pumpouts is recommended every three to five years, with the material transferred to a treatment facility for processing.

Restaurant grease traps, which need to be serviced at least semi-annually, have not been able to get pumped either.

“It’s been very difficult,” said Jay Araujo, who owns Jay’s Septic Service in Edgartown. “A septic system is supposed to be maintained; you don’t want to wait until you need it to be pumped. But right now, that’s all we are allowed to do.”

The problem began during the start of the pandemic, according to Edgartown wastewater facility manager Bill Burke. Sewage treatment facilities must maintain a careful balance between wastewater flow — which comes from residences and buildings hooked up to the town sewer — and septage, which is material from septic pumpouts. Because septage can be 40 to 50 times as concentrated as wastewater, the facility can only accept a small amount of it relative to flow during specific hours of the day, Mr. Burke explained.

When the pandemic started, a confluence of factors disturbed that careful calculus. With restaurants and other businesses on the town sewer shuttered, wasterwater flow plummeted at the plant, preventing the facility from accepting large amounts of septage — even as seasonal homeowners arrived on the Island in higher numbers and stayed for longer, causing an increase in the need for septic pumpouts. Combined with Covid-related restrictions for septic haulers and facility staff, it spelled trouble for the already-overburdened treatment facility.

Only around 1,450 of the approximately 17,000 buildings on the Island are connected to a town sewer, according to Mr. Burke.

“It became apparent during the first quarantine that the septage haulers wanted to bring in more septage,” he said. “Looking at the historical amount of septage that had come to the plant, myself, in conjunction with our engineer, we believed it to be too much.”

In response, the Edgartown wastewater commission decided to retain the engineering firm Tighe and Bond at a cost of $8,100 to conduct a cost-benefit evaluation on the facility’s septage intake. The study was initially delayed by the pandemic but got underway this summer, and is expected to finish within the next month. Possible future outcomes include prioritizing Edgartown residents for septic pumpouts at the facility, or installing a large septic holding tank at the site.

Either way, capacity is likely to be limited in the future, Mr. Burke said.

“We’re definitely scaling back,” he said. “We have a groundwater discharge permit by the state that we have to meet and it regulates how much nitrogen can leave the plant. My primary concern is to meet the wastewater flow. To violate the permit is never a pleasant thing.”

Edgartown town administrator James Hagerty said the facility brings in about $600,000 per year in revenue for the town from septic pumpouts. But flow numbers, as well as the health of “the bug,” a vernacular term for the naturally occurring bacteria used to break down waste as part of the facility’s biological filtering process, indicated future problems.

“If you looked at the bug . . . it wasn’t the healthiest looking,” Mr. Burke said. “There needs to be a balance.”

Mr. Hagerty and Mr. Burke, who began as facility manager in February and has nearly 30 years of experience, said revenue from septic pumpouts may pale compared with the long-term cost of overworking the facility. Meanwhile, the decision to limit septic capacity was temporary, Mr. Hagerty said, while the town evaluated its next steps and waited on results from the study.

“The conditions are not bad currently, but we’re taking a precautionary approach,” Mr. Hagerty said. “The problem financially is that we either pay a little now, or pay a lot more later. If we’re constantly accelerating the depreciation of the wastewater plant by taking in high volumes of septic, then I would rather lose $250,000 [in revenue] now, than have to pay $25 million later.”

The Island’s six septic haulers understand the dilemma but nonetheless find themselves in a temporary bind. With the future of the Edgartown plant unclear, they are scrambling to make plans to accommodate ever-increasing septic demand. Mr. Araujo has requested a temporary lease at the airport business park to install two 10,000-gallon, above-ground tanks for septic storage. Airport commissioners postponed the request until their next meeting after mulling questions about safety and ventilation.

“In principle they are sympathetic, and want to help out the Island,” airport director Geoff Freeman said. “They wanted more verification on containment of any potential rupture of a tank or hose line.”

Haulers are also exploring plans to take septic pumpouts off-Island as a long-term solution. Although mainland treatment facilities generally cost much less for dropoff than Edgartown, meaning prices might remain comparable, the logistics of procuring ferry reservations and staffing have been challenging, Mr. Araujo said. He is also concerned that come winter, when wastewater flows decrease, the town may not even be able to handle the emergency pumps.

“It’s all new for me,” Mr. Araujo said.

He calculated that of the 2.4 million gallons of septic waste brought to the Edgartown facility in 2019, his company was responsible for about 989,000 gallons. The company currently has 100 people on a waiting list for maintenance pumpouts.

“There are a lot of marginal septic systems on the Island, and with people being home more with Covid, the failing septic systems have reared their ugly head,” Mr. Araujo said. “My hope was that when summer was in full swing, their flows would be high enough that we could go back to operation as normal, but I just don’t think operation as normal before Covid is ever going happen again, because the plant can’t handle it.”

Mr. Burke also thought a reversion to pre-pandemic policy was unlikely, and said the town was doing its best to balance the needs of the plant with the needs of the Island while it awaited the results of the study.

“The intent of what we’re doing is that the Island has come to rely upon Edgartown for its wastewater needs,” Mr. Burke said. “So we’re taking the tight tanks, we’re taking the porta-toilets, we’re taking the failed systems, we’re taking the emergencies. We thought that was equitable.”