TECHNICAL REPORT
COST-EFFECTIVE COMPARISON OF
LAND APPLICATION AND
ADVANCED WASTEWATER TREATMENT
NOVEMBER 1975
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF WATER PROGRAM OPERATIONS
WASHINGTON, D.C. 20460
MCD47
-------
NOTES
To ord^r this publication, MCD-17, Technical Report, Cost-
Effectjve Comparison of Land Application & Advanced Wastewater
Treatment.
Write fio:
I
General Services Administration (8FSS)
Centralized Mailing List Services
Bldg. 41, Denver Federal Center
Denver, CO 80225
Please indicate the MCD number and title of publication.
-------
EPA-430/9-75-016
TECHNICAL REPORT
COST-EFFECTIVE COMPARISON OF LAND APPLICATION
AND ADVANCED WASTEWATER TREATMENT
BY
Charles E. Pound
Ronald W. Crites
Robert G. Smith
^1> rv
*i PRdtf"0
Belford L. Seabrook, P.E.
Project Officer
NOVEMBER 1975
prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF WATER PROGRAM OPERATIONS
WASHINGTON, D.C. 20460
MCD-17
-------
FOREWORD
This report is intended to be used for general cost
comparisons of advanced wastewater treatment and land
application systems. The curves shown in the figures are
presented only for comparative purposes and should not be
used to estimate costs of specific alternatives in facilities
plans.
The sensitivity of total costs of land application systems
to variations in design factors is illustrated for irri-
gation systems in Figure 2. The three conditions chosen
represent the variations that may be encountered in design
and are not intended to be regional stereotypes.
Variations in application rates, storage periods, and interest
rates were also studied independently for irrigation, over-
land flow, and infiltration-percolation systems. The
resulting curves exhibited only slight cost variations and
therefore were not included in this report.
-------
CONTENTS
Page
INTRODUCTION 1
APPROACH 2
COST COMPARISON OF AWT AND LAND APPLICATION
SYSTEMS - FIGURE 1 6
COST COMPARISON OF AWT AND IRRIGATION SYSTEMS
UNDER VARIABLE SITE CONDITIONS - FIGURE 2 8
VARIATION OF COST WITH CONVEYANCE DISTANCE
AND FLOW CAPACITY - TABLE 4 11
LAND PRICE RESULTING IN EQUAL TOTAL COSTS
OF AWT AND LAND APPLICATION SYSTEMS - FIGURE 3 12
FEDERAL AND LOCAL SHARE OF TOTAL COSTS - FIGURE 4 14
COST COMPONENT TABLES 16
EXAMPLES 20
REFERENCES 25
-------
TABLES
No.
1 AWT Systems 2
2 Effluent Quality Comparison for Land Treatment
and AWT Systems 3
3 Site Conditions for Land Application Systems 4
4 Conveyance Cost VS Flow Capacity 11
5 Component Costs for AWT Systems 16
6 Component Costs of Irrigation Systems
Under Condition 1 17
7 Component Costs of Irrigation Systems
Under Condition 2 17
8 Component Costs of Irrigation Systems
Under Condition 3 18
9 Component Costs for Overland Flow Systems 19
10 Component Costs for Infiltration-Percolation
Systems 19
11 Cost Comparison for Example 1 22
12 Cost Comparison for Case A 23
13 Cost Comparison for Case B 24
FIGURES
1 Costs of AWT and Land Application Systems 7
2 Costs of AWT and Irrigation Systems Under
Variable Site Conditions 9
3 Land Price Resulting in Equal Total Costs of
AWT and Land Application Systems 13
4 Federal and Local Share of Total Present
Worth Costs of AWT-4 and Irrigation Systems 15
11
-------
COST-EFFECTIVE COMPARISON OF LAND APPLICATION
AND ADVANCED WASTEWATER TREATMENT SYSTEMS
INTRODUCTION
Numerous misconceptions regarding the economic feasibility
of land application systems are involved in the controversy
over the role of land treatment processes used in place
of conventional advanced wastewater treatment (AWT). The
relative importance of costs for preapplication treatment,
conveyance, storage, application, and land must be assessed
for each case. Depending on local conditions, a long con-
veyance distance or a high land price may be economically
justifiable when the alternatives are compared in the
cost-effectiveness analysis.
The objectives of this report are to illustrate the sensi-
tivity of land application system costs to variations in
major design factors and to compare these costs with those
for conventional AWT systems. Four figures showing cost
curves have been produced for this purpose, and some major
implications from the analysis of these curves are listed.
The component costs for the curves are presented in tables
to illustrate their relative magnitudes and to allow re-
placement, additions, or deletions of cost components. Two
examples are included to illustrate the potential use of the
curves and tables.
Two other comparisons are made in addition to variations in
design factors. First, land price is shown in Figure 3 in
curves that represent equivalent total costs of AWT and land
application systems. These curves can be used to determine
the upper limits of land prices that would be feasible for
-------
various cases, or they can be used to determine the upper
limits of flow for which land application systems would be
comparable in cost to AWT systems for a given land price.
Second, the effect of federal grants was compared for
an irrigation system and an AWT system in Figure 4. The
local and federal shares were computed assuming land to
be eligible for grants except for use as a preapplication
treatment or storage site.
APPROACH
To compare typical costs of land application and AWT, the
technical reports, Costs of Wastewater Treatment by Land
Application [1] and A Guide to the Selection of Cost-
Effective Wastewater Treatment Systems [2], have been used.
Four AWT systems have been developed as shown in Table 1.
The effluent quality expected from these four systems, from
the three land application systems, and from activated sludge
and aerated lagoon systems is shown in Table 2.
Table 1. AWT SYSTEMS
System Constituents removed
Processes used
NH3-N
AWT-1
AWT-2 Total-N
AWT-3 Phosphorus and SS
AWT-4 Total N, P, and SS
Biological nitrification
Biological nitrification-denitrification
Tertiary, two-stage lime coagulation, and
filtration
Tertiary, two-stage lime coagulation,
filtration, and selective ion exchange
-------
Table 2. EFFLUENT QUALITY COMPARISON FOR
LAND TREATMENT AND AWT SYSTEMS
Effluent quality parameter, mg/1
System
Aerated lagoon
Activated sludge
Irrigation
Overland flow
Infiltration-percolation
AWT-1
AWT- 2
AWT- 3
AWT-4
BOD
35
20
1
5
5
12
15
5
5
SS
40
25
1
5
1
15
16
5
5
NH3-N
10
20
0.5
0.5
—
1
—
20
—
N03-N
20
10
2.5
2.5
10
29
—
10
—
Total N
30
30
3
3
10
30
3
30
3
P
8
8
0.1
5
2
8
8
0.5
0.5
Comparing the effluent qualities and pairing off land
application and AWT systems it appears that:
• Irrigation and AWT-4 produce effluents of similar
quality
• Overland flow and AWT-2 produce effluents of similar
quality
• Infiltration-percolation produces an effluent compar-
able in quality to AWT-1 and AWT-3
In estimating the effluent qualities in Table 2 for land appli-
cation systems it was assumed that preapplication treatment
would consist of biological oxidation using aerated lagoons.
The quality of effluent from land application processes is
approximately the same whether the wastewater applied is from
primary or secondary treatment according to Reed [3].
-------
The site conditions for the three land application systems
are given in Table 3. A comparison of system costs for
irrigation (Condition 2), overland flow* and infiltration-
percolation with the AWT costs is shown in Figure 1.
Table 3. SITE CONDITIONS FOR LAND APPLICATION SYSTEMS
Parameter
Conveyance
distance, miles
Storage period,
weeks
Application rate,
in . /wk
Land price ,
$/acre
Crop revenue,
S/acre
Underdrain
spacing, ft
Tailwater return,
% of applied effluent
Condition la
1
1
3
1,000
400
none
0
Irrigation
Condition 2b
5
10
2
2,000
300
200
10
Condition 3C
10
20
1.5
4,000
150
100
30
Overland flow Infiltration-percolation
5 5
5 1
6 12
2,000 2,000
100
—
__
a. Condition 1 represents a climate with mild winters, nearby site with well-drained loamy soil.
Application is by center pivot sprinkling.
b. Condition 2 represents a climate with moderately cold winters, moderately well-drained soil
underlain by poorly drained subsoil. Application is by center pivot sprinkling.
c. Condition 3 represents a cold climate, a distant site with poor drainage and rolling terrain
necessitating application by solid set sprinkling and surface runoff control.
-------
COMPARISON DATA
-------
COST COMPARISON OF AWT AND LAND APPLICATION SYSTEMS - FIGURE 1
Basis of Costs
1. EPA Treatment Plant Cost Index - 177.5
2. Interest rate - 5-5/8 percent
3. Recovery period - 20 years
4. Pretreatment using headworks, aerated lagoon,
chlorination, and administration and laboratory
facilities
5. Pumping station with 150 feet total head
6. Unlined storage reservoir with embankment protection
7. Conveyance by force main
8. Costs not included - water rights, relocation,
easements
Implications
1. In general, land application systems exhibit less
economy of scale than AWT systems. Thus, land
application systems tend to be more cost effective
at lower flow capacities when compared to a given
AWT system. For example, both irrigation and overland
flow under the stated design conditions have a
progressively lower total cost than AWT-1 as flow
capacities decrease below about 3 mgd and a
progressively higher total cost as flow capacities
increase beyond 3 mgd.
2. Under the stated conditions, infiltration-percolation
is the lowest cost land application system. Overland
flow and irrigation are nearly equal and exhibit a
relatively constant cost differential with respect to
infiltration-percolation and to one another.
3. All three land application systems under the stated
conditions are significantly more cost effective
than AWT-3 or AWT-4 (although effluent qualities
will vary) at flow capacities at least through 100 mgd.
-------
RRIGATION (CONDITION 2)
INFILTRATION-
PERCOLATION
3 4 56769
FLOW CAPACITY • MGD
NOTE: CONDITION 2 REPRESENTS A CLIMATE WITH MODERATELY COLD WINTERS, MODERATELY
WELL-DRAINED SOIL UNDERLAIN BY POORLY DRAINED SUBSOIL. APPLICATION IS BY
CENTER PIVOT SPRINKLING.
FIGURE 1. COSTS OF AWT AND LAND APPLICATION SYSTEMS
-------
4. Infiltration-percolation, under the stated conditions,
is cost competitive with activated sludge secondary
treatment.
5. Irrigation (Condition 2) and overland flow are cost
competitive with AWT-1 and AWT-2.
COST COMPARISON OF AWT AND IRRIGATION SYSTEMS UNDER VARIABLE
SITE CONDITIONS - FIGURE 2
Basis of Costs
1. EPA Treatment Plant Cost Index - 177.5
2. Interest rate - 5-5/8 percent
3. Recovery period - 20 years
4. Irrigation site conditions - see Table 3
5. Pretreatment using headworks, aerated lagoon,
chlorination, and administration and laboratory
facilities
6. Pumping station with 150 feet total head
7. Unlined storage reservoir with embankment protection
8. Conveyance by force main
9. Costs not included - water rights, relocation,
easements
Implications
1. Differences in site condition variables can result in
a cost variation of over 300 percent for an irrigation
system. Overland flow and infiltration-percolation
are also subject to similar cost variations with site
conditions although less extreme than irrigation
because of fewer cost component variables.
-------
1(0
FLOW CAPACITY - UGD
NOTE: CONDITION i REPRESENTS A CLIMATE WITH MILD WINTERS. NEARBY SITE WITH
WELL-DRAINED LOAMY SOIL. APPLICATION IS BY CENTER PIVOT SPRINKLING.
CONDITION 2 REPRESENTS A CLIMATE WITH MODERATELY COLD WINTERS, MODERATELY
WELL-DRAINED SOIL UNDERLAIN BY POORLY DRAINED SUBSOIL. APPLICATION IS BY
CENTER PIVOT SPRINKLING.
CONDITION 3 REPRESENTS A COLD CLIMATE. A DISTANT SITE WITH POOR DRAINAGE
AND ROLLING TERRAIN NECESSITATING APPLICATION BY SOLID SET SPRINKLING AND
SURFACE RUNOFF CONTROL
FIGURE 2. COSTS OF AWT AND IRRIGATION SYSTEMS
UNDER VARIABLE SITE CONDITIONS
-------
2. As conditions become more favorable for irrigation,
the total costs exhibit more economy of scale,
with the cost curves tending to have a shape
similar to the AWT system cost curves.
3. Under a combination of unfavorable conditions
(Condition 3) irrigation appears to be economically
competitive with AWT-3 and AWT-4 only at flows
less than about 3 mgd.
4. Under Condition 2, irrigation is decidedly more cost
effective than either AWT-3 or AWT-4 at all flows
less than 100 mgd and is competitive with AWT-1
and AWT-2 at flows less than about 20 mgd.
5. Under Condition 1, irrigation is significantly more
cost effective than activated sludge at all flows
less than 100 mgd.
6. Revenue produced from the sale of the crop is very
important to the total costs, especially under
Conditions 1 and 2.
10
-------
VARIATION OF COST WITH CONVEYANCE DISTANCE AND FLOW
CAPACITY - TABLE 4
Basis of Costs
1. EPA Treatment Plant Cost Index - 177.5
2. Interest rate - 5-5/8 percent
3. Recovery period - 20 years
4. Conveyance by force main
5. Costs not included - water rights, relocation,
easements
Table 4. CONVEYANCE COST VS FLOW CAPACITY
Cents per 1,000 Gallons
Distance —
miles
1
3
5
10
20
30
50
100
1
5
9
18
36
54
92
184
Average
1
.8
.4
.2
.3
.6
.9
.0
3
0.8
2.4
4.0
8.0
16.0
24.0
40.0
80
0
1
3
6
12
18
30
60
5
.6
.8
.0
.0
.0
.0
.0
10
0
1
2
4
8
12
20
40
.4
.2
.0
.0
.0
.0
.0
flow,
20
0.3
0.9
1.5
3.0
6.0
9.0
15.0
30
mgd
30
0.2
0.8
1.3
2.5
5.0
7.5
12.5
25
50
0.2
0.6
1.0
2.0
4.0
6.0
10.0
20
70
0.1
0.5
0.9
1.7
3.4
5.1
8.5
17
Implication
1. The total cost of land application systems is very
sensitive to conveyance distance at low flow capa-
city but becomes less sensitive as flow capacity in-
creases. For example, the cost of conveyance for a
1-mgd irrigation system (Condition 2) would represent
11 percent of the total cost at 3 miles of transmission,
but would increase to 29 percent at 10 miles and to
45 percent at 20 miles. The same conveyance distances
for a 50-mgd system would represent only 3, 9, and
16 percent of the total cost, respectively.
11
-------
LAND PRICE RESULTING IN EQUAL TOTAL COSTS OF AWT AND LAND
APPLICATION SYSTEMS - FIGURE 3
Basis of Costs
1. EPA Treatment Plant Cost Index - 177.5
2. Interest rate - 5-5/8 percent
3. Recovery period - 20 years
4. Irrigation site (Condition 2)
5. Pretreatment using headworks, aerated lagoons,
chlorination, and administration and laboratory
facilities
6. Pumping station with 150 feet total head
7. Unlined storage reservoir with embankment protection
i
8. Conveyance by force main
9. Costs not included - water rights, relocation,
easements
Implications
1. In general, the lower the flow capacity of the land
application system, the higher the price that can be
paid for land and still be economically competitive
with AWT systems.
2. In areas where land costs are low ($1,000 per acre
or less) irrigation (Condition 2) would be more
cost effective than AWT-4, AWT-3, and AWT-2.
Similarly, irrigation would be more cost effective
than AWT-1 at flows less than about 10 mgd. Overland
flow, under similar conditions, would be more cost
effective than AWT-2 at flows less than about
5 0 mgd.
12
-------
5678910 20
FLOW CAPACITY, MGD
30 40 50 60708090100
FIGURE 3. LAND PRICE RESULTING IN EQUAL TOTAL COSTS
OF AWT AND LAND APPLICATION SYSTEMS
13
-------
FEDERAL AND LOCAL SHARE OF TOTAL COST - FIGURE 4
Basis of Costs
1. EPA Treatment Plant Cost Index - 177.5
2. Federal grant funding at 75 percent of eligible
construction cost
3. Interest rate - 5-5/8 percent
4. Recovery period - 20 years
5. Irrigation site (Condition 2)
6. All land costs for irrigation except storage
site are considered eligible
7. Pretreatment using headworks, aerated lagoons,
chlorination, and administration and laboratory
facilities
8. Pumping station with 150 feet total head
9. Unlined storage reservoir with embankment protection
10. Conveyance by force main
11. Costs not included - water rights, relocation,
easements
Implications
1. The federal share of total costs represents a much
larger percentage of the total cost for land appli-
cation systems than for AWT systems. For example, the
federal share of a 10-mgd irrigation system represents
about 70 percent of the total cost, while the federal
share for the same size AWT-4 system represents about
35 percent of the total cost. This difference results
from the fact that the majority of the costs associated
with land application systems are capital costs of
which the federal share is 75 percent. In addition,
the operating and maintenance costs, which are paid
entirely out of the local share, are lower for land
applications relative to AWT systems and these costs
are reduced further through revenues from crops.
14
-------
3 45678 910 20 30 40 5060708090100
FLOW CAPACITY, MGD
FIGURE 4. FEDERAL AND LOCAL SHARE OF TOTAL PRESENT
WORTH COSTS OF AWT-4 AND IRRIGATION SYSTEMS
15
-------
For land application systems and AWT systems of
equal total costs, the local share of the land
application system cost will generally be lower
than the local share of the AWT system cost.
From this standpoint local agencies may tend to
look more favorably on land application systems
when total costs appear to be equal.
COST COMPONENT TABLES
To allow manipulation of system costs and further sensitivity
analyses as desired, the cost components of all the systems are
given in Tables 5 through 10. The sources of these costs are
the EPA reports [1,2]. The exception to this is the cost for
sludge disposal, which is estimated at $30 per ton for 1-mgd
secondary systems and $20 per ton for 100-mgd systems [4].
Table 5. COMPONENT COSTS FOR AWT SYSTEMS
Cents per 1,000 Gallons
Curve
designatio
Process [21
Headworks
Primary
Activated sludge
Disinfection
Sludge digestion
Sludgy drying
Sludge disposal
Administration
Subtotal
AWT-1
Nitrification
Total
AWT- 2
Nitrification
Denitrif ication
Total
AWT -3
Lime addition
Filtration
Sludge drying
Recalcination
Incineration
Total
AWT -4
AWT- 3
Ion exchange
Total
AA
Al
Cl
R
LI
Ol
~
G2
G2
H
F2
D
O7
Q3
P5-L1
I
1
2
6
19
2
4
6
3
3
48
11
59
11
9
68
12
11
9
24
6
111
111
14
125
Average flow.
.7
.7
.0
.8
.1
.0
.7
.2
.2
.0
.2
.0
.4
.6
.0
.0
.8
.0
.7
.7
.7
.0
.7
3
1.
3.
12.
1.
1.
3.
3.
1.
29.
6.
36.
6.
6.
42.
6.
7.
6.
17.
3.
70.
70.
11.
81.
5
4
2
0
9
9
8
5
7
4
8
2
8
2
4
0
9
3
0
8
4
4
0
4
1
2
9
1
1
3
3
1
23
5
29
5
5
34
4
6
5
14
2
57
57
9
66
.1
.4
.1
.6
.4
.2
.3
.3
.4
.6
.0
.6
.3
.3
.8
.7
.3
.0
.9
.1
.1
.8
.9
10
0.
1.
7.
1.
1.
2.
3.
0.
18.
4.
22.
4.
4.
27.
3.
5.
4.
12.
2.
45.
45.
8.
54.
mgd
50
8
7
0
3
0
6
1
9
4
5
9
5
4
3
4
3
4
0
0
5
5
5
0
0
0
4
1
0
1
2
0
12
3
15
3
3
19
1
3
3
7
1
29
29
6
35
.6
.9
.5
.0
.6
.9
.8
.4
.7
.2
.9
.2
.6
.5
.8
.2
.2
.3
.0
.2
.2
.5
.7
100
0.
0.
4.
1.
0.
1.
2.
0.
11.
2.
14.
2.
3.
17.
1.
2.
2.
7.
0.
26.
26.
5.
32.
4
8
0
0
6
8
5
3
4
8
2
8
6
8
5
5
9
0
8
1
1
9
0
16
-------
Table 6. COMPONENT COSTS OF
IRRIGATION SYSTEMS UNDER CONDITION 1
Variable
Effective flow
Field area
Total area
Costs
Pretreatment
Pumping
Conveyance
Application
system
Capital
Average flow, mgd
Unit 135 10 50
mgd 1.02 3.05 5.1 10.2 51
acres 90 270 450 900 4,500
acres 170 440 750 1,400 5,200
C/1,000 gal. 9.9 6.7 5.7 4.7 3.9
C/1,000 gal. 6.8 5.0 4.2 3.8 2.9
C/1,000 gal. 1.8 0.8 0.6 0.4 0.2
C/1,000 gal. 8.8 6.3 6.0 5.8 4.9
Operation
and maintenance C/1,000 gal. 11.0 8.5 7.9 7.1 5.3
Storage
Land
Crop revenue
Total
Variable
Effective flow
Field area
Total area
Tailwater, 10%
Costs
Pretreatment
Pumping
Transmission
Application
system
Capital
Operation and
maintenance
Underdrain
Capital
Operation and
maintenance
Tailwater
return
Capital
Operation and
maintenance
Storage
Land
Crop revenue
Total
C/1,000 gal. 0.7 0.5 0.5 0.4 0.3
C/1,000 gal. 2.6 2.3 2.3 2.2 1.9
C/1,000 gal. (9.9) (9.9) (9.9) (9.9) (9.9)
C/1,000 gal. 31.7 20.2 17.3 14.5 9.5
Table 7. COMPONENT COSTS OF
IRRIGATION SYSTEMS UNDER CONDITION 2
Average flow, mgd
Unit 13 5 10 50
mgd 1.24 3.7 6.2 12.4 62
acres 170 510 850 1,700 8,500
acres 275 750 1,200 2,200 10,500
mgd 0.1 0.3 0.5 1.0 5.0
C/1,000 gal. 9.9 6.7 5.7 4.7 3.9
C/1,000 gal. 6.8 5.0 4.2 3.8 2.9
C/1,000 gal. 9.2 4.2 2.8 2.0 1.0
C/1,000 gal. 11.6 9.3 8.8 8.1 7.9
C/1,000 gal. 13.0 10.2 9.7 8.9 8.0
C/1,000 gal. 2.5 2.3 2.3 2.3 2.3
C/1,000 gal. 1.3 0.9 0.8 0.7 0.5
C/1,000 gal. 0.5 0.2 0.2 0.1 0.1
C/1,000 gal. 0.1 0.1 0.1 0.1
C/1,000 gal. 3.5 2.9 2.8 2.4 2.2
C/1,000 gal. 8.5 7.7 7.4 6.8 6.5
C/1,000 gal. (13.7) (13.7) (13.7) (13.7) (13.7)
C/1,000 gal. 53.2 35.8 31.1 26.2 21.6
70
71.4
6,300
8,700
3.5
2.6
0.1
4.6
5.2
0.3
1.9
(9.9)
8.3
70
87
11,900
14,000
7.0
3.5
2.6
0.7
7.6
7.9
2.3
0.5
0.1
—
2.1
6.2
(13.7)
19.5
17
-------
Table 8. COMPONENT COSTS OF
IRRIGATION SYSTEMS UNDER CONDITION 3
Average flow,
Variable
Effective flow
Field area
Total area
Tailwater, 30%
Costs
Pretreatment
Pumping
Conveyance
Application
system
Capital
Operation and
maintenance
Underdrain
Capital
Operation and
maintenance
Tailwater return
Capital
Operation and
maintenance
Storage
Land
Crop revenue
Total
Unit
mgd
acres
acres
mgd
«/l,000
*/l,000
t/1,000
C/1,000
«/l,000
*/l,000
«/l,000
-------
Table 9. COMPONENT COSTS
FOR OVERLAND FLOW SYSTEMS
Average flow capacity
Cost component
Effective flow
Field area
Total area
Costs
Pretreatment
Pumping
Conveyance
Application
system
Capital
Operation and
maintenance
Storage
Land
Crop revenue
Total
Unit
mgd
acres
acres
0/1,000
0/1,000
0/1,000
0/1,000
0/1,000
0/1,000
0/1,000
0/1,000
0/1,000
gal.
gal.
gal.
gal.
gal.
gal.
gal.
gal.
gal.
1
1
53
130
9
«
9
11
7
2
4
_u
49
.2
.9
.8
.2
.6
.5
.3
.0
^5)
.8
3
3.7
159
360
6.7
5.0
4.2
8.9
5.8
1.6
3.8
(1.5)
34.5
5
6.2
265
570
5.7
4.2
2.8
7.9
5.4
1.4
3.6
(1.5)
29.9
10
12
530
1,100
4
3
2
6
4
1
3
(1
24
.4
.7
.8
.0
.5
.8
.2
.4
.5)
.9
, mgd
50
62
2,650
4,900
3
2
1
6
3
0
3
(1
20
.9
.9
.0
.0
.9
.9
.0
.5}
.1
70
81
3,710
6,500
3.5
2.6
0.7
5.8
3.8
0.9
2.8
(1.5)
18.6
Table 10. COMPONENT COSTS
FOR INFILTRATION-PERCOLATION SYSTEMS
Average flow capacity, mgd
Cost component
Effective flow
Total area
Costs
Pretreatment
Pumping
Conveyance
Application
system
Capital
Operation and
maintenance
Storage
Land
Total
Unit
mgd
acres
0/1,
0/1,
0/1,
0/1,
0/1,
0/1,
0/1,
0/1,
000
000
000
000
000
000
000
000
gal.
gal.
gal.
gal.
gal.
gal.
gal.
gal.
1
1.
46
9.
6.
9.
6.
6.
0.
1.
40.
92
9
8
2
8
0
7
4
8
3
3.
135
6.
5.
4.
4.
4.
0.
1.
26.
05
7
0
2
3
4
5
4
5
5
5.1
220
5.7
4.2
2.8
3.6
3.8
0.5
1.4
22.0
10
10.2
440
4.7
3.8
2.0
3.0
3.2
0.4
1.4
18.5
50
51
2,100
3.9
2.9
1.0
2.1
2.2
0.3
1.4
13.8
70
71.4
3,000
3.5
2.6
0.7
2.0
1.9
0.3
1.4
12.4
19
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EXAMPLES
The use of the comparative cost curves and the cost tables
is illustrated in the following hypothetical examples.
Example No. 1
Requirements. A new regional wastewater treatment facility
is to be constructed to provide a flow capacity of 10 mgd
and to meet the following effluent quality requirements for
surface water discharge:
BOD - 20 mg/1
SS , - 20 mg/1
Total N - 3 mg/1
P - No limit
Alternatives. A review of Table 2, showing the expected
effluent quality resulting from various methods of treatment,
indicates that three methods of treatment (AWT-2, overland
flow, and irrigation) would be possible selections that would
achieve the desired degree of treatment. The alternatives
considered in this case are described below:
Alternative A - Construct an AWT-2 treatment facility
that would provide conventional primary
treatment, secondary treatment by acti-
vated sludge, and nitrogen removal by
biological nitrification-denitrification.
Alternative Bl - Construct headworks and an aerated lagoon
as pretreatment for land application.
Construct an overland flow system on a
site located 3 miles from the pretreatment
site. The important site conditions and
preliminary design criteria are as follows,
20
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Soil type - clay
Application rate - 6 inches per week
Storage period - 5 weeks
Topography - rolling
Land cost - $1,000 per acre
Alternative B2 - Construct pretreatment facilities as in
Alternative Bl. Construct an irrigation
system on same site as Bl. The site
conditions are somewhat unfavorable for
irrigation and this is reflected in the
preliminary design criteria listed below.
Application rate - 1.5 inches per week
Storage period - 10 weeks
Underdrain interval - 100 feet
Tailwater return — 30 percent
Application system - solid set spray
Land cost - $1,000 per acre
Alternative C - Construct pretreatment facilities as in
Alternative B. Construct an irrigation
system on a site more favorable for
irrigation, located 5 miles from the pre-
treatment site. The important site
characteristics and preliminary design
criteria are listed below:
Soil type - sandy loam
Topography - flat
Application system - center pivot spray
Application rate - 3 inches per week
Storage period - 10 weeks
Land cost - $3,000 per acre
Underdrain interval - none
Tailwater return - none
Cost Comparison. The total cost of each of the alternatives
in cents per thousand gallons is determined in Table 11,
using the cited figures and tables.
21
-------
Table 11. COST COMPARISON FOR EXAMPLE 1
Alternative
A
Bl
B2
C
Cost component
AWT- 2
Total
Overland flow
Conveyance adjustment
Land cost adjustment
Total
Irrigation
Conveyance adjustment
Storage adjustment
Land cost adjustment
Total
Irrigation
Conveyance adjustment
Storage adjustment
Land cost adjustment
Total
Cost
C/1,000 gal.
27.0
27.0
24.9
-(2.0)
+ 1.2
-(3.4)
+(3.4 x 1/2)
22.4
70.1
-(4.1)
+ 2.0
-(4.9)
+ 2.4
-(20.9)
+(20.9 x 1/4)
49.8
14.5
-(0.4)
+ 2.0
-(0.4)
+ 2.4
-(2.2)
+(2.2 x 3)
22.5
Source
Figure 1
Table 9
Table 9
Table 4
Table 9
Table 9
Table 8
Table 8
Table 4
Table 8
Table 7
Table 8
Table 8
Table 6
Table 6
Table 4
Table 6
Table 7
Table 6
Table 6
Conclusions. The lowest cost alternatives are Bl and C.
Since the two alternatives are approximately equal at this
level of cost comparison, a more detailed cost estimate and
comparison is indicated. One cost component to evaluate
carefully is that of crop revenue, since this component
represents a substantial reduction in the total cost of
Alternative C (see Table 6).
22
-------
Example No. 2
Requirements. An existing 20-mgd activated sludge plant is
required to upgrade its effluent quality to meet the following
criteria:
BOD - 10 mg/1
SS - 10 mg/1
N - 3 mg/1
P - 0.5 mg/1
Alternatives. It is evident from a review of Table 2 that
the only methods of treatment capable of providing the neces-
sary degree of treatment are AWT-4 and irrigation. In this
example, the cost of AWT-4 is compared with that of irrigation
under varying conditions of conveyance distance (Case A) and
land costs (Case B). Since secondary treatment is existing,
activated sludge or aerated lagoon will not be necessary.
Case A -
Consider a moderately favorable site for
irrigation, a distance of 5 miles away from
the existing treatment plant site. How
much can be paid for land and have the
irrigation system competitive with the
AWT-4 system?
Table 12. COST COMPARISON FOR CASE A
Treatment
me thod
AWT-4
Irrigation
Cost component
AWT-4
Existing activated
sludge adjustment
Total
Irrigation system
Aerated lagoon
adjustment
Land cost
Subtotal
Amount available
for land = (28.0-13.0)
Total area, acres
Cost
C/1,000 gal. Source
44.
-(16.
28.
24.
-(4.
-(6.
13.
15.
4,300
0
0)
0
0
3)
7)
6
0
Figure
Figure
Figure
Figure
Table
Table
1
1
1
1
7
7
Allowable cost/acre
20 mgd (15fr/l,000 gal.)(103)
(0.0154) (4,300 acres)
23
4,500
-------
Conclusions. Under the assumed site conditions for the
irrigation system, as much as $4,500 per acre could be paid
for land and have the irrigation system competitive with
AWT-4.
Case B - Consider a moderately favorable irrigation site
at a cost of $2,000 per acre. How far away from
the existing treatment plant could the site be
and have the irrigation system competitive with
AWT-4?
Table 13. COST COMPARISON FOR CASE B
Treatment
method
AWT- 4
Irrigation
Cost component
From Case A
Irrigation system
Aerated lagoon adjustment
Conveyance cost
Subtotal
Amount available for
conveyance = (28.0 - 18.0)
Allowable distance, miles
Cost
C/1,000 gal.
28.0
24.0
-(4.3)
-(1.7)
18.0
10.0
33
Source
Figure 1
Figure 1
Figure 1
Table 7
__
Table 4
Conclusions. Under the assumed site conditions for the
irrigation system, wastewater could be conveyed as far as
33 miles and have irrigation be competitive with AWT-4.
Special conditions such as river or highway crossings and
easements may add substantial costs and reduce this distance
somewhat.
24
-------
REFERENCES
1. Pound, C.E., R.W. Crites, and D.A. Griffes. Costs
of Wastewater Treatment by Land Application. EPA-430/
9-75-003. Office of Water Program Operations,
Environmental Protection Agency. June 1975.
2. Van Note, R.H., et al. A Guide to the Selection of
Cost-Effective Wastewater Treatment Systems. EPA-430/
9-75-002. Office of Water Program Operations,
Environmental Protection Agency. July 1975.
3. Reed, S.C., e't al. Pretreatment Requirements for Land
Application of Wastewaters. (Presented at the Second
ASCE National Conference on Environmental Research,
Development, and Design. University of Florida. July
20-23, 1975.)
4. Process Design Manual for Sludge Treatment and
Disposal. Environmental Protection Agency. EPA-625/
1-74-006, October 1974.
"U.S. GOVERKHENT PRINTING OFFICE: 1978 — 777-066/1112 REGION HO. 8
25
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