Two llamas, four goats, a pair of swans, several ducks, a few turtles, deer, fox, coyotes, and raccoon all sound like an advertisement for a community zoo. It’s actually a list of some of the critters that make their homes around three lagoons at the Marion (Massachusetts) Wastewater Treatment Plant.

“We even have a bunch of chickens, and way more Canada geese than we care to see,” says Frank Cooper, superintendent of the 0.59 mgd (design) sequential batch reactor (SBR) plant.

“But lots of people enjoy the wildlife, and bird-watchers can’t say enough about the many species we attract.”

Critical capacity

The attraction to wildlife consists of 20 acres of facultative lagoons that have served Marion since 1971. In the 1990s, UV disinfection was added. Disc filters replaced sand filters in 2002.

A nutrient removal upgrade in 2005 added the SBRs. Since then, the lagoons handle only flow equalization, along with enjoyment to bird-watchers and wildlife lovers.

“We have a lot of I&I, so storage capacity is important to us,” says Cooper. The lagoons are important to the wildlife enthusiasts, too, but their existence is being threatened by tightening regulations and potential environmental concerns.

The plant still operates under the original NPDES permit; city officials are waiting for the U.S. EPA’s response to their comments on the draft of a new permit. The plant diverts excess influent to the lagoons until the two SBRs can catch up. Average flow to the plant is nearly 0.5 mgd, but high rain and snow seasons can produce as much as four times that amount.

Two pairs each of 30 hp and 100 hp KSB pumps deliver excess flow to either one 10-acre or two 5-acre lagoons. Level sensors at the lagoons generate alarms through a Wonderware SCADA system (Schneider Electric - Invensys). A Flowserve electric actuator positions an aluminum weir gate valve to divert flow from the headworks to the lagoons. “Even though we are highly automated, the operators control the weir gate locally,” says Nathaniel Munafo, assistant plant operator.

A small amount of flow used to backwash the disc filters also goes to the lagoons. Return flow for processing in the SBRs is delivered through two Hayward Gordon ChopX-3A 5 hp pumps and a 4-inch return line. “The lagoons are a buffer and critical to our operation,” Cooper says.

Effluent is discharged to an unnamed, non-spring-fed drainage stream that flows to Aucoot Cove, a saltwater body attached to Buzzards Bay. The initial permit draft says the plant must stop using the lagoons for solids management or else drain, dredge and line them.

Quality viewing

The lagoons are fenced and gated, and have no public access. Bird-watchers and wildlife lovers observe from the top of a capped landfill next to the plant. For an even better look, the plant allows observers to view the lagoons from the top of the headworks building. “It gets them up about 10 feet so they can look over the fence,” says Cooper.

Cooper and his staff go out to the lagoons daily to take readings, and they see a variety of wildlife on every trip. “The lagoons are vibrant and full of life, and since we aerate, they don’t totally freeze over in winter, and we get birds all year long,” Cooper says.

The lagoons rest on a glacial till and have 40 years of solids at the bottom that act as a cake filter. Lining will be expensive, but some other solutions would be cost-prohibitive to the nearly 1,650 ratepayers of the seaside community.

“The lagoons are an active part of what we do, and the plant’s got to have some overflow capacity,” Cooper says. “I would prefer to keep all 20 acres, but from an economic standpoint, we may need to shrink them for lining in order to get our permit.”

Snapping turtles, banded kingfishers, osprey and a family of otters are just some of the less typical critters that have thrived in the lagoons. Some residents of Marion even say the lineage of the remaining goats can be traced to early pilgrims in the area. Says Cooper, “What I know is that I’ll be bummed if the lagoons go away.”