TECH ENVIRONMENTAL PRESS RELEASES

2008-11-21: Tech VP Lannan Discusses CSO Odor Control with Boston Globe, Dorchester Reporter

BOSTON, MA - Tech Environmental's Vice President, Michael Lannan, was extensively quoted in recent articles in the Boston Globe and Dorchester Reporter regarding a Tech project to examine potential odor impacts from a proposed odor control system for the North Dorchester Bay Combined Sewer Overflow Tunnel.

Tech examined the system on behalf of Corcoran Jennison, a local developer concerned about the potential impacts from odorant releases upon Carson Beach, the nearby residential and business community, and future residential development.

While the Massachusetts Water Resources Authority, the state agency responsible for building and operating the sewer tunnel, regards the odor concern as a non-issue, Tech's analysis showed that peak odorant releases could impact a large area around the odor control facility.

The Boston Globe article, "Odor threat jeopardizes Dorchester condo plan," quotes Lannan's evocative explanation of the potential odor situation:

Corcoran Jennison officials do not believe that the odor-control facility, which is scheduled to be built on their property line next year, is designed to handle the peak loads of hydrogen sulfide, the gas that creates that rotten egg smell, especially after heavy rains.

In one Corcoran Jennison model, Lannan, the company's odor-control specialist, suggested that the stench on the worst days could stretch across South Boston and Dorchester. He delineated the smelliest areas on a map with three circles: red, yellow, and green.

"Inside the red, it would be like a bathroom you'd go into and want to leave," he said. "Inside the yellow, it would be like a bathroom you'd go into and probably continue to do what you needed to do, but you'd want to get out of there as soon as possible. And in the green, it would be like a bathroom."

Lannan recommends several changes, including building the facility underground and replac ing a large above-ground structure with a simple, short ventilation stack. By doing so, Lannan said, the MWRA would improve the aesthetics - a concern of Corcoran Jennison's - but more importantly, eliminate downwash, a phenomenon that occurs when wind traveling above a structure, like a building, redirects a previously rising plume downward toward the ground.

One of the key issues in the debate, as discussed in the Dorchester Reporter's article ("Odor facility clouds future of Bayside project"), is the potential intensification of odor impacts from "downwash effects" related to the design of the odor control structure:

The odor control building would sit on the up-end of a 2.1-mile long, 17-foot wide tunnel that could store up to 18 million gallons of storm water that, during severe rainstorms, would be mixed with a smaller amount of raw sewage. A federal court mandated the work along with several other projects of its kind in the late 80s, the aim being a clean up of Boston Harbor.

The odor control technology uses activated carbon filters to reduce the offending emanations, eventually releasing the air offset by incoming stormwater from a 40-foot-high stack. But Michael Lannan of Tech Environmental, Corcoran's hired consultant, contends that the wind blowing in from the ocean would flow over the 35-foot high brick building, carrying the emerging effluents from the 40-foot high stack down to the ground on the other side.

"It touches down almost immediately, before there's any dispersion," he said.

Corcoran Jennison is asking that the odor control apparatus be placed underground, eliminating the need for a 35-foot-high structure and allowing for a smaller and more unobtrusive stack. Tech's analysis indicated that an underground odor control system, such as the one in use for Seattle's CSO tunnel, would improve the dispersion of odorants, while also minimizing aesthetic impacts.

Despite this difference of opinion, Tech recently provided odor training services to MWRA, teaching operators how to use Jerome hydrogen sulfide meters as part of proactive odor management efforts.

Tech Environmental uses odor control expertise and computer modeling to study and mitigate odorous impacts for municipal, commercial, and industrial clients. Tech has been a leading air quality consulting firm in the Northeast for over two decades.

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