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 35
AFM 91-19 / TM 5-629 / NAVFAC MO-314
24 May 1989
CHAPTER 6
DETERMINING THE COST-EFFECTIVENESS OF PGR
Section A -- General Discussion
result from using PGRs is computed. Finally,
the results are evaluated to determine whether
the savings that might be generated would result
6-1. The Importance of Determining Cost-
in real dollar savings, or if, instead, the freed
Effectiveness. The previous chapter emphasized
personnel and equipment assets would be used
the need to consider local conditions and to
for other worthwhile tasks.
conduct local testing before adopting PGRs.
c. Documents on which the calculations can
Even when local conditions and the results of
be made are provided in attachments 22 through
testing seem favorable, however, grounds main-
25. Document A (attachment 22) is used to
tenance practices should not be changed without
determine the hourly costs of personnel. Docu-
comparing the costs of the alternatives. This
ment B (attachment 23) is used to determine the
cost-comparison, the demonstrated effects of
hourly costs of equipment. Using the hourly
PGRs, the availability of equipment and trained
costs of personnel and equipment, the grounds
personnel, and safety should all be considered in
maintenance manager can use document C (at-
deciding the most cost-effective maintenance
tachment 24) to calculate the costs of mowing
practice.
and spraying operations on particular parcels of
land. Document D (attachment 25) is then used
6-2. Calculating and Documenting Costs of Al-
to compare costs and to determine the cost-
ternatives:
effectiveness of using PGRs.
a. The calculations described in this chapter
d. Documents A through D can also be used
can be made easily by hand. They can also be
to calculate and compare the costs of other
adapted readily to a personal computer. The
maintenance practices and equipment, to prepare
factors considered are:
budgets, and to determine manpower require-
(a) The costs of mowing.
ments.
(2) The costs of applying PGRs.
(3) The length of time PGRs are expected to
6-3. An Illustrative Example. The use of docu-
suppress the growth of the grass.
ments A through D is illustrated in the remain-
(4) The reduction in mowing that is expected
der of this chapter with a fictitous example. Air
when PGRs are used.
Base Somewhere is located in the temperate
b. The calculations are made in four steps.
zone, and PGRs are being considered for use on
cool-season grasses on 2300 acres. The require-
First, the costs per hour are calculated for each
ment without PGRs is to mow the parcels shown
type of worker employed in the mowing and
in table 6-1 every 2 weeks. In addition to the
spraying operations; next, the cost of the equip-
ment used is calculated on a per hour basis;
grass, there are large concentrations of weeds
that would have to be controlled before the full
third, the costs of mowing and spraying opera-
effect of the plan growth regulators could be
tions on specific parcels of land are computed;
and, fourth, the savings or cost that would
realized.
Table 6-1. Mowing Requirement at Air Base Somewhere.
Parcel
Capability
Equipment
of Equipment
No.
Description
Size
Used
2.5 a/h
1
Tractor
Runway &
2,000
Taxiways
acres
Mower
2
0.5 a/h
200
36" Riding
Mower
Areas
acres
1.15 a/h
Obstructed
21" Power
3
100
Areas
acres
Mower
1,615 ft2/h
4
Fence
100,000
Weedeater
f t2
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