Page 266 - Materials Chemistry, Second Edition

CAT3525_C08.qxd 1/29/2005 10:03 AM Page 237
Composting MSW 237
● Access and onsite roads
● Site facilities and security

While designing the facility, the possibility for future expansion should be considered.

8.11.1 PREPROCESSING AREA
A preprocessing area provides space to receive feedstock and to sort and separate materials.
Receiving materials in a preprocessing area eliminates the need for delivery trucks to unload
directly into piles in inclement weather. The size and design of the preprocessing area depends on
the amount of incoming material and the way the materials are collected and sorted. The tipping
area (i.e., where incoming feedstocks are unloaded) is often under a roof to avoid the effects of
severe weather.

8.11.2 PROCESSING AREA
The processing area includes the composting pad and the curing area. The pad surface should be
paved to prevent infiltration. Adequate drainage is also essential. Precipitation collected on the pads
can be diverted through the use of drains. Poor drainage will result in ponding of water, saturated
composting materials, muddy and unsightly site conditions, odor production, and excessive runoff
and leachate from the site (Rynk, 1992).
Proper ventilation is required in enclosed preprocessing and processing areas because the air
within the structure can be sources of bioaerosol, odors, dust, and excess moisture. Air filters can
be installed to clean the exhaust air and biofilters to absorb odor-producing compounds. Vents can
be situated over preprocessing equipment (e.g., conveyor belts, trommels) to reduce dust and odors.
A curing area is used to store the compost for the last phase of the composting process, to
allow the material to stabilize. The material should be fairly stable and therefore runoff, ground-
water contamination, and other siting issues should be of less concern. The curing area needs less
space, about one quarter of the area of the compost pad (University of Connecticut, 1989; Richard
et al., 1990).

8.11.3 BUFFER ZONE
The larger the buffer zone, the greater the acceptance of the facility among residents. The buffer
zone installed at a composting facility depends on the type of feedstock being composted and the
level of technology (i.e., monitoring and odor control) employed at the facility. State and local reg-
ulations frequently require minimal buffer zone sizes or specify the distances that the composting
operations must be from property lines, residences, or adjacent businesses and from surface water
or water supplies.
The buffer zone must be larger than the composting pad, particularly when the operation is
adjacent to residential areas or businesses. Enclosed facilities may function adequately with a
smaller buffer zone since operations are more closely controlled.
When designing the facility, prevailing wind direction should be considered. The buffer zone
should be extended in this direction. This will help in minimizing the transport of odor and
bioaerosols downwind of the facility.

8.11.4 SITE FACILITIES AND SECURITY

Composting operations might require several buildings to house various site functions, from main-
tenance and administrative work to personnel facilities. Access to the site must be controlled to pre-
vent vandalism, especially arson and illegal dumping. At a minimum, the access roads must be
secured with a fence, cable, locked gate, or similar barrier.