Geography Reference
In-Depth Information
5.
D
ISCUSSION
By modeling the current collection system and proposing two alternate
scenarios, results confirm the initial hypothesis that the current collection
system is highly inefficient and can be improved. This is most evident through
the long collection time, lengthy distance traveled, and substantial number of
trips to the transfer station on each collection day. The obvious problem with
the current collection system is the number of solid waste companies and the
varying number of customers each serves. Manifesting the problem is the size
of the collection truck used by several companies, particularly those with a
mini hauler that serve too few or too many households. For instance,
Companies F and G serve such a low percentage of households that each
finishes collection in less than an hour on each day. They are accounting for
unnecessary miles traveled and trips to the transfer station that could otherwise
be served by larger companies. Conversely, Companies K and M with a mini
hauler serve a larger percentage of customers. This requires several trips to the
transfer station translating to a much longer collection time and distance
traveled. For comparison purposes, Company E with only 23 more households
than Company K requires approximately half the time, distance, and trips to
transfer station because it utilizes a mid-size hauler. However, the same
argument can be made against Companies I and K that have large haulers but
only serve a few households. Regardless of how one analyzes current
collection, the system is highly inefficient from the number of solid waste
collectors, most truck sizes, number of miles traveled, collection time, and the
number of trips to the transfer station. Fortunately, this research proposed and
demonstrated alternate scenarios that greatly improve upon these variables
regardless which scenario is chosen.
Scenario 2 - Controlled Collection improves current collection by 50
percent in all variables with the exception of total collection time. This
reduction cannot solely be attributed to decreasing the number of solid waste
collectors to six but also because their households were geographically
clustered. With each collector serving a particular cluster, the amount of
driving across the entire city was reduced. The only driving outside their
cluster involved trips to the transfer station. This translated to a 70 percent
reduction in the combined total distance traveled on each of the four collection
days. The elimination of mini-size haulers also reduces miles traveled. The
elimination of several companies and geographic clustering of customers
presented in Scenario 2 is a similar approach instituted by the City of Portland,
Oregon, USA twenty years ago. Solid waste, recycling, and composting
