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Some details emerge for wastewater treatment upgrades

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Marlborough – Although the City Council voted June 25 against a bond request to fund an upgrade the westerly wastewater treatment plant, the city of Marlborough still must gear up for major changes at its wastewater treatment plants.

The upgrades to the plants would be in response to a federal and state mandate to lower the level of phosphorus emissions from 0.75 milligrams per liter to 0.1 milligrams per liter at the plants.

Current plans add an extra process for scrubbing the water when it is processed at both plants. Work on the westerly plant is tentatively scheduled to start in June 2008 and take two years, after which work on the easterly plant would begin.

The water at the westerly plant flows in from the area of Marlborough west of Interstate 495 and from Northborough, which shares the facility.

The water flows through grinders and several clarifiers, and is aerated with bacteria, which breaks down the contaminants in the water. The water is then released into the Assabet River a few hundred yards from the site.

"All of this would occur in the river but it would take miles and miles and would ultimately degrade the river quality," said Doran Crouse, assistant commissioner for utilities of the Department of Public Works, which runs the plant.

The water flowing from Marlborough comes mostly from industrial and commercial properties.

"We have a lot of hotels on this side of the city and they are substantial water and sewer users," Crouse said.

The westerly plant will be upgraded with new buildings and a new process to remove phosphorus from the water flow. The new equipment will be housed indoors, in contrast to the existing plant, because it is susceptible to freezing.

City officials are evaluating three competing processes to remove the phosphorus. Three weeks ago the city received proposals from three companies.

"The initial costs are pretty close for all three," said Harry Butland, chief operator at the plant.

But in making a decision, city has hired outside engineers to evaluate the proposals, also looking at operating costs and whether the systems meet the 0.1 milligram per liter standard.

As part of the upgrade, the plant will see daily capacity rise from 2.89 million gallons per day to 4.4 million gallons per day. There is currently little room for expansion at the plant.

"Marlborough's capacity is nearly used up," Crouse said.

The city has applied to the state to allow the additional flow to go into the Assabet River and the state is considering the proposal. If the state turns it down, the city may have to put the additional flow into the ground. That would require clearing 40 acres on the west side of Boundary Street, which borders the facility, and constructing sandy basins to allow the water to seep into the aquifer. The construction would add $15 million to the price tag for the westerly plant, which could rise from $30.6 million to $47.5 million, according to plans submitted by Mayor Nancy Stevens to the City Council.

City officials said sending the water into the ground would be of limited benefit to the environment, due to the cutting of trees, and because the basins would be located only a few hundred yards from the river.

"It's so close to the river the treated effluent would get to the river in short order," Crouse said.

The city is also considering another option for the site, which would see Northborough construct its own new facility across the road and cease to use the westerly plant at all.

Short URL: http://www.communityadvocate.com/?p=39

Posted by on Jun 29 2007. Filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry

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