Page 134 - Solid Waste Analysis and Minimization a Systems Approach

112 METRICS AND PERFORMANCE MEASUREMENT FOR SOLID WASTE MANAGEMENT

measure success toward meeting a goal. In this case, measuring a company’s waste
generation and recycling levels. Traditionally, solid waste generation and recycling
levels are reported by total output. For example, the plant generated 150 tons of solid
waste this month, of this amount 15 tons, or 10 percent, were recycled. This measure-
ment approach has a very serious shortcoming. The primary flaw is that is does not
consider production levels or resource inputs. For example, if two similar manufac-
turing plants generated the same amounts of solid waste, but the second plant has only
half the production volume, the second plant is not doing a good job of managing its
waste streams. Several other approaches have been developed to compensate for these
flaws and allow for an equal “apples-to-apples” comparison. Five of the most common
metrics by which solid waste generation can be measured are

1 Absolute measures
2 Measures indexed to a production output–based quantity
3 Measures indexed to a production input–based quantity
4 Measures indexed to throughput
5 Measures indexed to a production activity

All except the first of these metrics are based on the ratio of generation to some
measure of business activity.

7.2.1 ABSOLUTE MEASURES

A comparison of the mass of solid waste generated in 1 year to the mass that is gen-
erated in another year is an absolute measure of waste generation. Such measurements
are consistent and easy to understand, for example 1 lb of plastic scrap generated last
year is equal to 1 lb of plastic scrap generated this year. The major drawback is that
they ignore production levels or business activities associated with waste generation.
For example, if a manufacturing plant reduces it total solid waste generation by
50 percent, it might indicate a major effort to reduce waste or it might be associated
with a large drop in production volume, such as the loss of a large contract that accounts
for 50 percent of its total production volume. The solution to this problem is to nor-
malize the data or index solid waste generation to some measure of production.

7.2.2 MEASURES INDEXED TO OUTPUT
Solid waste can be indexed to the mass of products, number of products, or dollar
value of products. A good example of this in the automobile industry is waste per vehi-
cle produced. Using this index, the company will now have a more meaningful compar-
ison of waste generation rates at different production levels. A drawback of this
approach is that it does not consider significant changes to output. For example, if the
automobile plant shifts from producing sport utility vehicles to compact hybrid cars,
waste per vehicle would be expected to drop too. This drop may not be linked to a
solid waste reduction program, but a major change in business processes.