Pre-Filed Testimony and Exhibits of David Raphael - Vermont Public ...

Aesthetic Assessment of the Proposed Beaver Wood Biomass Facility
2. The Quechee Analysis
travelers would linger due to any scenic views or unique landscape qualities.
Nonetheless, views to the site will be readily apparent, and the elements of the
biomass power plant are not particularly attractive and will constitute a change in
the landscape and represent an industrial land use.
Biomass electricity is created through direct combustion. The facilities (boilers)
produce steam to use either within an industrial process, or to produce electricity
directly. They can also produce heat, which is then captured for one purpose or
another. As such, the Fair Haven facility is expected to produce two possible plumes
depending on the outside temperature, which need to be accounted for in this
analysis. One is from the 180-foot tall stack and the other from the two cell cooling
towers. The plumes are the same for both in that when the outside air is at or near
saturation, the tower and/or stack adds more water vapor to the air. Saturated air
with liquid water droplets can be discharged and this is what is seen as fog. This
typically occurs on cool, humid days and can be mistaken as smoke.
The developer has provided the following narrative about plume visibility:
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Air leaving the cooling tower is usually saturated with moisture and is wanner than
the ambient air, causing a wet exhaust plume to he created. The saturated exhaust
plume may be visible or not depending on the specific meteorological conditions. This
plume will also vary in size depending on meteorological conditions and operational
factors. Conditions favoring a condensed plume occur more frequently in the fail
and winter seasons, as atmospheric conditions, such as air tempcratl4re and relative
humidity, arc niorc favorable during these periods for plume formation. Also, plume
formation tends to occur more frequently during nighttime hours and during
adverse weather conditions.
Industry research indicates that the visible plume formation will occur 20% of the
time during visible hours and will stay within the facility boundary during all
seasons. The estimated downward visible plume length will be less than 300 feet
and the estimated plume visible height can reach up to 300 feet above ground level,
depending on meteorological conditions. In the winter the plume length and height
may be 20% larger. Plume breadth is estimated at 40 to 50 feet.
The boiler chimney plume is formed for all the similar reasons as the cooling tower
plume, and the height and width is all deternnned hi 1 operational and weather
conditions. At times the detached plume will he almost horizontal and at other times
it is almost straight up. The plume length in either direction, horizontal or
vertical, is estimated to be 150 ft or less with a diameter of approximately 30 feet.