WSP06476

• File Number: 8271.300
• Description: Colorado River Basin Salinity Control Program - General Information and Publications-Reports
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 6/1/1978
• Title: Salinity Management Options for the Colorado River -- Part 1 of 2 -- Title Page - Page 168
• Water Supply Pro - Doc Type: Report/Study

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Table 29. Test for significantly different sample means.

Estimated Mean Lifetime (Years)

Phoenix -
I tern Boulder City -
Henderson
(735 mg/i)

Galvanized Wastewater Pipes
Galvanized Water Pipes
Water Heater
Toilet Flushing Mechanisms
Brass Paucets
Clothes Washers
Dishwashers
Evaporative Coolers
Garbage Disposals

42.23
16.39
7.79
6.18
9.48
8.69
7.28
8.96
6.03

Las Vegas-
Tucson
(500 mg/l)

Statistical
Significance

40.15
19.85
9.66
8.02
10.28
8.63
9.01
7.23
7.58

No difference
Different at 0.05
Different at 0,02
Different at 0.10
No difference
No difference
Different at 0.02
No difference
Different at 0.05

present worth of differing lengths of life attributable
to different levels of TDS. The objective of this
procedure was to determine the annual costs of
replacement required to maintain the services of a
certain household item over a 6O.year period.
Damages were based on the capital replacement costs
of household items in 1975 using an 8 percent discount
rate. The results are in 1975 dollars which enables a
direct comparison to be made with the estimates for
the Los Angeles area.

Cost streams were calculated for each significant
item in Table 23 at both 500 mg/I and 735 mg/l
following the Same assumptions used in the Los
Angeles study. Replacement was considered to occur
at the end of the lifetime of the previous unit. Costs
were adjusted for the final replacement period to
equal 60 years which reflected actual costs incurred
for this less than full life segment. For example, in the
case of water heaters. lump sum costs of replacement
occurred every 9.66 years after the initial investment,
thus, replacing the unit five times covering 57.96
years of the 50.year household life. Costs for the
remaining 2.04 years (less than the average economic
lifetimes) were based on the relationship of replace.

ment costs for tbis segment to costs required for a full
economic life of 9.66 years and discounted in the same
manner as previous lump sums.

The present value of the cost streams for
galvanized water pipes, toilet flushing mechanisms,
water heaters, dishwashers, and garbage disposals
are presented in Table 24. The difference between the
resulting present value sum at 735 mg/I and 500
mg/I is considered to be amount of additional costs per
unit over a 5O.year period due to the increasing TDS.

Since different households mayor may not
contain some or all of the items, a typical household for
each area was construed. Table 25 shows the number
of units per household considered to be typical for the
Central Arizona service area (SMSA's of Phoenix and
Tucson) and the lower mainstem of the Colorado River
(Las Vegas SMSA and municipal communities along
the river to the Mexican border).

Total lifetime replacement costs were converted
to costs per mg/l by dividing 235 (735.500) into the
difference of the cost streams displayed in Table 24.
These values were multiplied by the weighing factors

Table~. Pre.ent value of replacing significant household items over 60-year /ife (8 percent, 1975 dollars).

Phoenix - Las Vegas -
Boulder City -
Item Henderson Tucson Difference
(735 mg/!) (500 mg/l)
Galvanized Water Pipes 827.11 758.63 68.48
Toilet Flushing Mechanisms 65.38 53.72 11.66
Water Heaters 351.18 301.90 49.28
Dishwashers 519.22 445.17 74.05
Garbage Disposals 173.33 145.59 27.74

23