Page 151 - Materials Chemistry, Second Edition

CAT3525_C05.qxd 1/27/2005 11:15 AM Page 122
122 Waste Management Practices: Municipal, Hazardous, and Industrial
Major considerations in building design include durability of construction, adequate size for tipping
and processing, minimization of overhead obstructions to trucks, and flexibility of layout.
Transfer Station Sizing
The transfer station should have a sufficiently large capacity to manage the wastes that are expected
to be received at the facility throughout its entire operating life. Factors to be considered in deter-
mining the appropriate size of a transfer facility include (U.S. EPA, 2003):

• Capacity of collection vehicles using the facility
• Number of days of storage on tipping floor
• Time required to unload collection vehicles
• Number of vehicles that will use the station and their expected days and hours of arrival
(design to accommodate peak requirements)
• Waste sorting or processing to be accomplished at the facility
• Transfer trailer capacity
• Hours of station operation
• Availability of transfer trailers awaiting for loading
• Time required to attach and disconnect trailers from tractors or compactors
• Time required to load trailers.

Transfer stations are usually designed to have 1/2 to 2 days of storage capacity. The collection
vehicle unloading area is usually the waste storage area and a waste sorting area. When planning
the unloading area, adequate space should be provided for vehicle and equipment maneuvering. To
minimize the space required, the facility should be designed so that collection vehicles back into
the unloading position. Adequate space should also be available for offices, employee facilities, and
other facility-related activities. Formulas for determining transfer station capacity are presented
below (U.S. EPA, 2003).
Stations with Surge Pits
Based on the rate at which wastes can be unloaded from collection vehicles:

C P (L/W)(60H /T )F (5.2)
C W C
Based on the rate at which transfer trailers are loaded:

C (P N 60H )/(T B) (5.3)
t t t
Direct Dump Stations

C N P F 60H /[(P /P )(W/L )T ] B (5.4)
n t W t C n C
Hopper Compaction Stations

C (N P F 60H )/(P /P T ) B (5.5)
n t W t C c
Push-Pit Compaction Stations

C (N P F 60H )/[(P /P )(W/L )T ] B B (5.6)
C
p
W
t
c
C
p t
Where C station capacity (tons/day)
P collection vehicle payloads (tons)
C
L total length of dumping space (ft)