This animation illustrates how a standard Polychem chain and flight scraper system is assembled and installed.
Although the city is awaiting formal notification from the federal Environmental Protection Agency, it appears the wastewater treatment plant outflow into the Westfield River has little or no impact on migrating shad.
"We haven't got final word from the EPA," David S. Billips, superintendent of sewers and wastewater, said of the spring study. "But, I think it's acceptable to them and we won't be required to repeat the study."
The Environmental Protection Agency mandated the study as a requirement for the wastewater treatment permit granted several years ago for expansion of the plant.
Billips said the $18 million expansion will increase daily capacity from 4 million to 6.1 million gallons. The expanded plant is expected to become operational next month, he said.
The shad study, initiated in 2002, required that the shad be studied under both high- and low-water flow conditions.
Heavy rains, however, had the river flowing higher than usual that year and the ensuing $70,000 study did not met the criteria for low flows.
During the first study, biologists captured 21 shad at the DSI/FiberMark Fish Ladder and Eelway in West Springfield, outfitted them with transmitters and tracked them to see whether they were affected by the plant's effluent plume extending from the plant's outfall on Mainline Drive.
Although only two of the shad made it as far as the outflow, project officials said it demonstrated the effluent had no impact on the fish.
In the second phase of the study, which cost approximately $45,000, biologists captured 20 shad, again outfitted them with transmitters and released them in the dam's fore bay May 18.
By the end of the study, two weeks later, eight shad had moved past the outflow, at least six of which swam between a quarter and three-quarters of a mile further upstream to deep water ideal for spawning, aquatic biologist J. Nathan Henderson said.
Of the remaining fish, three remained in the fore bay for the length of the study and two moved out of the fore bay only to swim downstream over the dam, Henderson said.
"If these fish are removed from the results of the study, 53 percent of the fish passed the outfall," stated Henderson in a study memo. "These are very encouraging results."