EPA/530/SW-619
OCTOBER 1977
-2====
case studies
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COST OF LANDSPREADING AND HAULING SLUDGE
FROM MUNICIPAL WASTEWATER TREATMENT PLANTS
Case Studies
This report (SW-619) was written
by R. KENT ANDERSON
with data collection and case writing
by Mr. Anderson, Bruce R. Meddle, Ted Hillmer, and Al Geswein
U.S. ENVIRONMENTAL PROTECTION AGENCY
1977
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An environmental protection publication (SW-619) in the solid waste
management series. Mention of commercial products does not constitute
endorsement by the U.S. Government. Editing and technical content of
this report were the responsibilities of the Systems Management Division
of the Office of Solid Waste.
Single copies of this publication are available from Solid Waste
Information, U.S. Environmental Protection Agency, Cincinnati, Ohio,
45258.
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FOREWORD
It has been estimated that about 25 percent of the municipal
wastewater treatment plant sludge produced in the United States is
disposed of by landspreading. Landspreading is the practice of applying
sludges to the land so as to utilize certain inherent characteristics of
the material for agricultural benefits. While landspreading of sludges
is a common practice, the cost of this operation is seldom known. The
primary reasons for this being poor record keeping, or not being able to
break down the total operating cost for the sewage treatment plant by
function. Therefore this study was designed to determine the cost of
existing landspreading operations rather than to evaluate the potential
environmental benefits or hazards of landspreading.
111
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CONTENTS
Page
I. Introduction and Summary 1
A. Purpose 1
B. Scope of Study 1
C. Findings 3
II. Current Sludge Handling Practices 4
A. Transportation Systems 4
B. Landspreading Systems 7
III. Economics 17
Appendix Case Studies 31
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COST OF LANDSPREADING AND HAULING SLUDGE FROM
MUNICIPAL WASTEWATER TREATMENT PLANTS
by R. Kent Anderson*
I. INTRODUCTION AND SUMMARY
A. Purpose
This report presents an analysis of the cost of disposing of
municipal wastewater treatment sludge on land by existing operations.
It is based on an on-site survey of 24 communities with small to medium-
sized plants, i.e.. all with throughputs of less than 100 million gallons
per day (MGD). The analysis differs from other studies in that much of
the available literature has been developed for large communities with
sizable quantities of sludge. For these communities, landspreading costs
are considerably higher than for smaller communities due to longer haul
distance, increased capital requirements, and higher labor rates. The
24 city survey was thus designed to provide reliable cost information
for small communities interested in landspreading wastewater treatment
sludge on land. However, it should be noted that the cost of new
operations may be somewhat higher due to increased cost of equipment.
B. Scope of Study
The communities selected for the study were chosen on the basis of
(1) treatment plant size, and (2) sludge dewatering processes employed.
This was done to obtain as wide a range of landspreading practices and
costs as possible.
Three different plant sizes were selected:
Average Daily Flow Number of Communities
(MGD)
< 5 7
5-10 4
> 10 13
For purposes of this study, plants processing over 10 MGD are referred
to as large plants, 5-10 MGD as medium-sized plants, and less than 5 MGD
as small plants. Table 1 presents a list of the communities chosen with
their average daily flow.
Using the average daily flow in MGD as the major means of cat-
egorizing the communities, an effort was also made to obtain a balanced
selection of liquid and dewatered haul systems for each size category.
* Mr. Anderson is a sanitary engineer with the Special Wastes Branch,
Office of Solid Waste, U. S. Environmental Protection Agency,
Washington, D. C.
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TABLE 1
TREATMENT PLANTS SELECTED
AVERAGE FLOW
LARGE TREATMENT PLANTS (MGD)
Toledo, Ohio 92
Louisville, Kentucky 90
Grand Rapids, Michigan 47
Salt Lake City, Utah 41
Salem, Oregon 28
Springfield, Ohio 20
Anderson, Indiana 18
York, Pennsylvania 16
LaCrosse, Wisconsin 14
Macon, Georgia 13
Appleton, Wisconsin 12
Bethlehem, Pennsylvania 12
Danville, Virginia 10.5
MEDIUM TREATMENT PLANTS
Sheboygan, Wisconsin 10
Greeley, Colorado 6.5
Belleville, Illinois 5.5
Littleton/ Colorado 5
SMALL TREATMENT PLANTS
Lebanon, Pennsylvania 4
Fort Pierce, Florida 3.5
Rochelle, Illinois 3.2
Greene County, Ohio 2.6
Collinsville, Illinois 1.2
Front Royal, Virginia 1.2
Lawrenceville, Illinois .5
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Nearly half of the communities selected used two systems to handle their
sludge. Reasons for this include the fact that many communities had
insufficient handling capacity in their primary system, and that seasonal
restrictions in conjunction with limited storage capacity prevented the
use of only a liquid system. The following breakdown was therefore
obtained for the 24 sites:
Type of Sludge Plant Size
Small Medium Large
Liquid 538
Dewatered
Vacuum Filter 218
Sand Drying Beds 032
Centrifuge 001
Lagoon 001
To determine the cost of landspreading, data was collected on
sludge quantities and detailed cost breakdowns during an on-site visit
to each of the communities. However, certain assumptions were made to
make the data comparable. All equipment was depreciated at 8 percent
interest. The depreciation period used for vehicles was 8 years,
stationary equipment was 10 years, while Buildings were depreciated over
20 years. In addition, a 10 percent contingency factor was added to the
cost of each system to cover such items as administrative overhead.
C. Findings *
1. The landspreading of liquid sludge was found to be far less
expensive than landspreading sludge dewatered by vacuum
filtration.
Analysis of the data developed during the course of this study
indicates that landspreading liquid sludge is far less expensive
than landspreading sludge dewatered by vacuum filtration. Indeed,
the average cost of the dewatering process alone ($61/dry ton) was
found to be considerably more expensive than the entire haul and
landspreading cost for liquid sludge. Those communities that
disposed of liquid sludge had an average cost of $32 per dry ton,
while those that dewatered their sludge averaged $87 per dry ton.
Even for those communities that disposed of both liquid and dewatered
sludge, the vacuum filtered sludge operation was two and a half
times more expensive than the liquid haul operation. Since most
communities spread the liquid sludge on the land but only dump the
dewatered sludge in piles for the landowner to spread at his own
expense, the dewatered sludge operation would be even more expensive
under comparable conditions.
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2. Personnel costs represented the largest single cost item for both
liquid and dewatered sludge landspreading.
Of the $32 per dry ton cost for liquid sludge disposal,
approximately $13, or 42 percent of the total, was expended for
personnel. As would be expected, the round trip haul time involved
in transporting the sludge is the major personnel cost item.
For the combined operation of dewatering and hauling vacuum
filtered sludge, the average cost per dry ton was $87. As with liquid
haul, personnel is the largest cost item in the vacuum filtered
sludge disposal operation. It accounts for 22 percent of the
total, followed by chemicals at 20 percent and utilities at 16
percent. With vacuum filtered sludge, the dewatering operation had
an average cost per dry ton of $61. Personnel, again, was the
largest cost item at 36 percent of the total, followed by chemicals
at 24 percent and maintenance on the vacuum filters at 17 percent.
3. Liquid sludge was more readily acceptable to the farming
community than dewatered sludge.
While none of the municipalities surveyed encountered great
resistance to their sludge landspreading practices, liquid sludge
was sought with much more frequency and enthusiasm than dewatered
sludge. This preference on the part of the farmer is due both to
the cost differential (the municipality always spreads the liquid
sludge on the fields, but not necessarily the dewatered), and to
the fact that dewatered sludge is more difficult to handle and
apply evenly.
II. CURRENT SLUDGE HANDLING PRACTICES
The desirability and feasibility of sludge landspreading is dependent
upon many factors. Although cost is a consideration in the selection of
a sludge utilization or disposal alternative, it does not appear to
always be the prime factor. Many communities find that disposal site
availability, transportation modes and application methods suitable for
either liquid or dewatered sludge landspreading, are more critical than
cost in selecting the system or systems to be used in disposing of their
sludge. A brief discussion of the transportation and landspreading
systems employed by the 24 communities follows.
A. Transportation Systems
1. Liquid Sludge
Liquid sludge is most commonly hauled by truck, although
pipelines, barges, and rail tank cars are also possible modes of
transportation. Of the 16 communities surveyed that hauled liquid
sludge, all used trucks as their sole conveyance mode.
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Truck capacity varied widely among the communities surveyed;
the smallest capacity was 1,400 gallons, while the largest was a
6,000 gallon tractor trailer. Two of the 16 communities used
tractor trailers. Although these were not large communities,
they generated liquid sludges with extremely low percentages of
solids which account for their need for trucks with larger capacities.
The average, as well as the median, truck capacity for the liquid
haul systems was 2,500 gallons.
The communities surveyed used from one to six trucks per plant.
Although two of the plants that handled larger quantities of
liquid sludge utilized the largest truck fleets, one of the smallest
plants had two trucks which were only utilized 7 percent of the
time. Because the capital cost for trucks amounts to 16 percent of
the total cost of disposing of liquid sludge, a reduction in excess
truck capacity could result in a cost savings. However, at some
plants, excess truck capacity was necessary since the sludge
generated in the course of an entire year was hauled during the
few months that disposal sites were available for use. In these
communities sludge was usually stored in oversized digesters or
inoperable digesters.
The typical community surveyed used one or two truck drivers.
The number of drivers employed was closely tied to the number of
trucks, and not necessarily to plant size. Table 2 shows the
number of trucks and drivers per community along with averages and
medians.
Haul distance ranged from one half mile to 30 miles round
trip, with an average round trip distance of 12 miles. Many of
the communities surveyed used haul distance as a criterion for
disposal site selection, and would not normally haul outside of
a five or ten mile radius of the treatment plant. The time required
to drive to and from the utilization sites varied from five minutes
to 60 minutes with a median round trip time of 25 minutes.
2. Dewatered Sludge
For the 16 cities that spread dewatered sludge on the land, the
transportation system usually consisted of one to three dump trucks
operated on a part-time basis. Capacity of the trucks ranged from
2 1/2 cubic yards to 30 cubic yard tractor trailers. At three of the
cities, the sludge hauling operation was contracted to a private
hauler who used larger capacity trucks and transported the sludge a
greater distance. For the city operated systems, the average truck
capacity was 8 cubic yards. The number of trucks and their size
usually increased with increased sludge production, except where the
sludge was spread on plant property. As would be expected, the
transportation costs were minimal (usually less than one dollar per dry
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Table 2
Truck Drivers and Trucks Utilized
in the Liquid Haul Operations
Number of
Truck
City Drivers
Anderson, Ind.
Belleville, 111.
Bethlehem, Pa.
Collinsville, 111.
Danville, Va.
Ft. Pierce, Fla.
Front Royal, Va.
Greeley, Colo.
Greene Co. , Ohio
LaCrosse, Wise.
Lebanon , Pa .
Macon , Ga .
Salem, Ore.
Springfield, Ohio
York, Pa.
Average
Median
5
2
1
2
2
2
1
1
1
2
1
1
1
1
4
1.8
1
Yearly
Percent
Each Worked
46
18
15
10; 40
60
40; 90
5
90
38
100
14
14
80
19
100
53
46
Number
of
Trucks
6
2
1
1
2
2
1
1
2
1
2
1
1
2
5
2
2
Yearly
Percent
Each Used
38
18
15
50
60
65
5
90
19
200*
7
14
80
10
80
48
38
*A two-shift operation.
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ton) if the sludge was disposed of on plant property, i.e., within a
very short haul distance. One city utilized two truck drivers full time,
while the remainder only used one driver. Table 3 shows the number
of trucks and drivers per community along with averages and medians.
The haul distances for dewatered sludge ranged from one
quarter mile to 90 miles round trip, with an average round trip
distance of 16 miles and a median distance of 10 miles. This
required an average round trip driving time of 37 minutes. In
comparing the average driving time of 28 minutes for the liquid
systems and 37 minutes for the dewatered systems, it appears that
the cities included in the survey took longer to transport their
dewatered sludge than their liquid sludge. However, Toledo, Ohio
hauls their dewatered sludge a far greater distance and has a
longer driving time than any other city surveyed. If Toledo's
system is excluded from the dewatered sludge analysis, the average
round trip driving time is 29 minutes. This indicates that the
driving times for both liquid and dewatered sludge hauling are
nearly identical. Therefore, from the communities surveyed, distance
or haul time to disposal sites was not a reason for or justification
to dewater the communities' sludge. However, dewatering does
result in far less material for transportation.
B. Landspreading Systems
1. Liquid Sludge
All the communities surveyed spread liquid sludge directly from
the truck. * The breakdown of liquid spreading mechanisms is
as follows: one injected the sludge into the soil with a subsod
injector on the rear of the truck; three used a pressurized spray
nozzle; three used rear mounted splash plates; five used a rear
mounted "T" pipe; and four did not use any distribution device.
In order to insure a uniform application of liquid sludge,
the application rate must be geared to the ground speed of the truck
and independent of the hydraulic head created by the sludge remaining
in the tank. Otherwise, when the truck is driven down hill, or
near the end of the load the application rate will decrease markedly.
If no distribution device was utilized, the application tended to
be rather uneven. In these cases, the sludge flows directly from a
valve at the rear of the truck, and covers a 2 to 3 foot wide swath
After the site visits were made, Greene County, Ohio, began utilizing
a sprinkler irrigation system. The irrigation system consists of
a farm tractor driven centrifugal pump, 1,500 feet of irrigation pipe
with a single riser and nozzle. Using this system, their 6,000
gallon tractor trailer can be unloaded from the roadway in 20 minutes.
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Table 3
Truck Drivers and Trucks Utilized
in the Dewatered Haul Operations
Number of
Truck
City Drivers
Anderson, Ind.
Belleville, 111.
Bethlehem, Pa.
LaCrosse, Wise.
Lawrenceville, 111.
Louisville, Ky.
Rochelle, 111.
Salt Lake City,
Utah
Springfield, Ohio
York, Pa.
Average
Median
1
1
1
2
1
1
1
1
1
1
1.1
1
Yearly
Percent
Each Worked
30
• 5
30
100
0.5
100
75
12
34
100
48.6
32
Number
of
Trucks
2
1
1
2
1
3
3
1
2
2
1.8
2
Yearly
Percent
Each Used*
15
5
30
100
0.5
33
25
12
17
50
28.8
21
*In addition, some trucks are used an additional amount of time in a
storage capacity while a load of sludge is being dewatered.
8
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as the truck is driven across the field. In order to completely
cover the field, the truck must be driven on previously applied
sludge which results in both poor traction and tracking of sludge
onto roadways. Figure 1 shows an extreme case of applying sludge
without a distribution system. In this example, the fields were
too wet to traverse with a truck so sludge was applied with a hose
emanating from a tractor trailer parked on the roadway. Since this
picture was taken, the system has been abandoned in favor of a
sprinkler irrigation system because of the uncontrollable and
spotty application rate received with the previous system.
A splash plate or perforated "T" pipe will eliminate some of
the distribution problem by applying sludge over an area at least
as wide as the width of the truck. However, even with a distri-
bution system of this sort, a much heavier application will be made
at the start as compared to the end of unloading unless the speed
that the truck advances across the field is steadily decreased to
compensate for the steadily decreasing hydraulic head. Figures 2,
3, and 4 illustrate various types of "T" pipes. Figure 5 provides
an example of a "T" pipe with a splash deflector device for more
even distribution.
The pressurized injection or distribution systems will eliminate
these problems of tracking sludge onto roadways and of uneven
application. By pressure spraying sludge from the side or rear of
the truck, a wide enough area can be covered to eliminate the need
of having to drive on previously applied land. Also the application
rate is not dependent upon the quantity remaining in the tank or
whether the truck is being driven up or down hill. The injection
system has additional advantages in that a follow-up operation to
incorporate the sludge into the soil is not needed. Many states
require or recommend that surface applied sludge be disced or
plowed under. Also, this system virtually eliminates the chance of
odors, greatly reduces the chance of sludge loss due to erosion or
loss of nutrients to the atmosphere. The injection system has the
disadvantage of greater power requirements for unloading while any
pressurized discharge system could have the potential disadvantage
of pump maintainance. Figures 6 and 7 illustrate two types of
pressure systems. Figure 6 is a side discharge, pressure spray
system. Figure 7 is a rear mounted pressure system with splash
plate.
Although there is a wide variation in the effectiveness of the
various distribution devices employed, there appears to be little
correlation between the acceptability of the sludge to the farmer
and the effectiveness of the distribution system. In general,
liquid sludge landspreading systems were considered desirable by
the farming community, regardless of the transportation system or
application method employed.
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Figure l--Tractor Trailer with Hose in Greene County, Ohio
10
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. < ',.
('.< I ».t
Figure 2—Open End "T" Pipe in Ft. Pierce, Florida
11
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Figure 3 —Slotted "T" Pipe in Springfield, Ohio
I .
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Figure 4—Perforated "T" Pipe in Front Royal, Virginia
13
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Figure
5__-T"' Plpe with Splash Deflector Device in Bethlehem, Pennsylvania
14
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Figure 6—Side Discharge, Pressure Spray System in York, Pennsylvania
15
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Figure 7—Big Wheel Pressure System with Splash Plate in Collinsville, Illinois
16
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2. Dewatered Sludge
Most of the communities surveyed hauled dewatered sludge to
the farm site and then dumped the sludge in piles. The landowner
was responsible for spreading and incorporating the sludge into
the soil. One exception to this was in Appleton, Wisconsin. Here,
the City contracted with a firm to haul the sludge to farmland. When
the driver arrived at the site, he dumped the load of sludge adjacent
to the previously applied area and used a tracked dozer at the site
to spread his load. At the end of the day, a four wheel drive farm
tractor is used to plow the area which had received sludge that day.
In most cases, there was no charge to the farmer for this service.
Figure 8 illustrates sludge after spreading but prior to incorporation
into the soil.
Many of the cities that dewatered sludge stockpiled at least a
portion of their sludge on the treatment property for local citizens
to obtain. The major advantage of this system is that the city does
not need to locate receiving areas nor bear the expense of hauling the
sludge long distances.
In some cases, the municipality found it more difficult
to dispose of its dewatered sludge than its liquid sludge. In
York, 'Pennsylvania, for example, the municipality is hauling liquid
sludge to 40 farms. But it has only been able to locate two farms
that will accept its dewatered sludge, primarily because the farmer
would have to spread the sludge and incorporate it into the land
himself. In another community, Bethlehem, Pennsylvania, the
dewatered sludge is typically landfilled because of a lack of
interest on the part of the farming community.
III. ECONOMICS
A majority of the communities visited did not maintain detailed
records on either the quantities of sludge handled, or the various cost
factors involved in the disposal operation. As a result, some of the
quantitative data utilized in this analysis are estimated values derived
from interviews with treatment plant personnel and city hall offices.
The data are nevertheless considered to be reliable and well within the
range of sludge landspreading costs of existing systems. However, the
communities studied in the survey are not necessarily representative of
all communities using the various disposal methods. The cost of new
operations may be higher than those found in this survey due to in-
creased costs of capital items. In some cases, however, the reported
cost may be too high because'a 10 percent contingency factor was added
to the total cost of each system. This contingency factor was added to
cover miscellaneous costs such as administrative overhead. For purposes
of this survey, sludge disposal costs include all post stabilization
processes.
17
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Figure 8—Spread Vacuum Filtered Sludge in Appleton, Wisconsin
18
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In analyzing the cost data, Sheboygan, Wisconsin, had unusually
high costs for the handling of both their liquid and vacuum filtered
sludges. Sheboygan's liquid haul operation was the only contracted
liquid disposal system surveyed, and was over 50 percent higher than the
next most costly operation. It was impossible to determine the cost for
disposal of Sheboygan's dewatered sludge since the City's incineration
costs were not available. Also, the City's dewatering costs were nearly
three times higher than the next most costly dewatering operation. The
high dewatering costs are mainly attributed to high depreciation charges,
expensive chemical requirements and high personnel costs. Because these
costs are so much higher than those obtained from any of the other
cities visited, they are not considered representative and have, therefore,
not been included in the analysis.
Of the communities surveyed, 16 disposed of all or part of their
sludge as a liquid at an average cost per dry ton of $32. In comparison,
11 communities disposed of part or all of their sludge after dewatering
by vacuum filtration for a total cost of $87 per dry ton. Five com-
munities used sand drying beds to dewater their sludge prior to disposal
for a total average per dry ton cost of $14. In addition one city each
used lagooning and centrifuging to dewater their sludge prior to disposal
at a total cost of $9 per dry ton and $20 per dry ton respectively. At
the plants which dewatered their sludge by sand drying beds, lagoons and
centrifuges, the reported costs are most likely lower than would be the
case for another community initiating these practices. With all three
of the systems, the cost of trucking the dewatered sludge was very low
or nonexistent since the dried sludge was usually used on site or stock-
piled for citizen use. Also the drying beds and lagoons were older
installations that did not have any depreciation charges. Many com-
munities also used secondhand trucks for transporting sludge which
resulted in lower depreciation costs. Tables 4 and 5 present summaries
of the cost data.
1. Liquid Sludge
At the plants that disposed of part or all of their sludge as
a liquid, the cost of disposal for the average dry ton of sludge
was $32. However, this varied from a low of $5 per dry ton to a
high of $81 per dry ton (Sheboygan1s cost is $125 per dry ton).
When comparing the size of operation to the cost per dry ton, the
data points are widely scattered and there is no apparent relationship
between annual quantity of sludge hauled and its associated cost
per dry ton. However, when comparing cost per dry ton to round
trip haul time (Figure 9), there appears to be a very strong
relationship.
In this case, a line (linear mode) was fitted to the data
using regression analysis. One standard deviation was used to
19
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Table 4
Liquid Sludge Landspreading Cost Summary
Community
Anderson, Indiana
Belleville, Illinois
Bethlehem, Pennsylvania
Collinsville, Illinois
Danville, Virginia
Ft. Pierce, Florida
Front Royal , Virginia
Greeley, Colorado
Greene County, Ohio
LaCrosse , Wisconsin
Lebanon, Pennsylvania
Macon, Georgia
Salem, Oregon
Sheboygan, Wisconsin
Springfield, Ohio
York, Pennsylvania
Liquid Sludge Produced
(Dry tons/year)
2,960
500
140
540
1,490
390
900
700
380
710
180
170
1,150
670
520
1,360
Total Cost
($/dry ton)
19
24
47
34
22
81
5
22
40
49
28
8
40
125
22
73
AVERAGE
AVERAGE Excluding Sheboygan
798 Weighted Average 37
806 Weighted Average 32
20
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Table 5
Dewatered Sludge Landspreading Cost Summary
Community
Dewatered
Sludge
Produced
(Dry tons/yr)
Dewatering
Cost
($/dry ton)
Average
Average Excluding
Sheboygan
3,205 weighted 68
average
3,366 weighted 61
average
Total
Cost
($/dry ton)
Vacuum Filter
Anderson, Ind.
Appleton, Wise.
Bethlehem, Pa.
Grand Rapids , Mich .
LaCrosse, Wise.
Lawrenceville , 111.
Louisville, Ky.
Rochelle, 111.
Sheboygan, Wise.
Toledo , Ohio
York, Pa.
900
7,700
460
320
3,650
70
4,590
1,950
790
16,250
970
48
25
110
48
68
120
33
75
380
77
140
53
42
120
54
81
190
50
89
not available
117
165
87
Drying Beds
Belleville, 111.
Grand Rapids, Mich.
Greeley, Colo.
Littleton , Colo .
Salt Lake City, Utah
500
2,930
500
510
1,410
33
7
8
12
1
34
15
8
13
1
Average
Centrifuge
Salt Lake City, Utah
Lagoon
Springfield, Ohio
1,170 weighted 8
average
6,500 20
2,180
12
20
21
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80 -
to
to
O
H
J-l
Q
J-i
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create the band on the figure with one standard deviation being +_
$7.14 per dry ton at any point from the central line. A "t" test
at 11 degrees of freedom indicates that the slope is significant at
the 99 percent level. In determining the variance of a multiple
regression, the data indicate that changes in haul time explain 91
percent of the variation in cost of disposal. As one might expect,
then, haul time is a good prediction of a community's cost of
disposing of its liquid sludge.
A similar analysis was performed comparing cost per ton ex-
cluding depreciation charges to haul time. A comparison of the
results indicates that haul time is a better indicator of cost per
dry ton when depreciation is included. As would be expected, the
analysis also showed that depreciation is an important cost factor
for those communities which have new transport vehicles.
For the liquid haul operations, the major cost category was
personnel which accounted for an average of 42 percent of the total
cost of sludge disposal. The next highest cost category was vehicle
operation and maintenance with an average of 19 percent of the
total followed by capital cost at 16 percent, fringe benefits
at 14 percent and utilities and miscellaneous at 9 percent. Figure 10
illustrates the cost breakdown by major cost category.
2. Dewatered Sludge
a. Vacuum Filtration
Of the 24 plants visited, 16 dewatered part or all of their
sludge. Eleven of the plants that dewatered sludge used vacuum
filters in their normal operation with a weighted average dry ton
disposal cost of $87. This cost varied between a low of $42 and a
high of $190. If only the cost of dewatering sludge is considered,
the average dry ton cost is $61 with a range of $25 to $140. In
Sheboygan, the dewatering cost, using the City's figures, is $380
per dry ton. Figure 11 plots dewatering cost per dry ton versus
annual dry tons processed while Figure 12 plots total cost for
disposal of vacuum filtered sludge versus sludge volume. Because
of the limited data, no attempt has been made to draw conclusions
from these figures.
With vacuum filtration, the major average cost categories were
personnel at 22 percent of the total cost, chemicals at 20 percent,
and utilities at 16 percent. In addition, vehicle operation and
maintenance, vacuum filter operation and maintenance, depreciation
and fringe benefits each accounted for 9 to 12 percent of the total
cost as shown in Figure 13.
23
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VEHICLE OPERATION
AND MAINTENANCE
FRINGE
BENEFITS
14%
CAPITAL
16%
UTILITIES
S OTHER
9%
PERSONNEL
42%
Figure 10—Breakdown of Total Annual Cost for Liquid Haul Systems
24
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140 -
120 -
to
en
a
o
-------
NJ
C
o
H
-------
VACUUM
FILTER
O & M
UTILITIES
& OTHER
FRINGE
BENEFITS
9%
Figure 13—Breakdown of Total Annual Cost for Vacuum Filtered Sludge
27
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2. Dewatered Sludge
b. Sand Drying Beds
Five of the plants dewatered part or all of their sludge
on sand drying beds for an average dry ton disposal cost of $12.
This cost varied between a low of one dollar per dry ton and a high
of $34. If only the cost of dewatering the sludge is considered,
the average dry ton cost is $8 with a range of one dollar to $33.
Of the five plants, four have little or no cost for transporting and
disposing of the sludge once it is removed from the beds since the
dried sludge is used on plant property or stockpiled for removal by
local citizens. Based on costs for other survey cities of comparable
size with dewatered sludges, trucking away from the plant could
easily increase these costs by $10 to $20 per dry ton. In addition,
all of the drying beds were older installations that were fully
depreciated and were, for the most part, only used on a part time
basis. As a result there was usually very little maintenance work
performed on the beds to keep them operating at their maximum
efficiency. Because of these factors, the observed costs for the
sand bed dewatering operation as well as the limited disposal costs
encountered, amount to about one third of the predicted operation and
maintenance cost for the dewatering operation. Therefore, although
the sand drying beds that were observed provided for a very in-
expensive means to dewater sludge, they are not representative of
newer nor continually utilized systems.
3. Comparative Cost Data
Of the cities surveyed, four (excluding Sheboygan) hauled
both liquid and dewatered sludge (Anderson, Indiana; Bethlehem,
Pennsylvania; LaCrosse, Wisconsin; and York, Pennsylvania).
Table 6 presents data from these four communities.
This table shows that the cost for disposal of the average
dry ton of sludge as a liquid was $38. However, for the same
cities the cost for vacuum filtered sludge was $93. Therefore,
on an average, the cities that used both methods paid almost two
and a half times more per dry ton for the disposal of vacuum filtered
than liquid sludge. The major reasons why these communities
dewatered a portion of their sludge and liquid hauled the remainder
were that they could not dispose of liquid sludge year-round because
of either cropping practices or weather conditions. Some of the
communities visited eliminated the traditional problem of only
being able to spread liquid sludge during certain seasons by
"Sludge Processing Transportation and Disposal/Resource Recovery:
A Planning Perspective, J. Michael Wyatt and Paul E. White, Jr.,
U.S.E.P.A. Contract No. 68-01-3104 by Engineering Science, Inc.
(December 197b).
28
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Table 6
Comparative Data on frour Cities
ro
(Ł>
LIQUID
COMMUNITY
Anderson, Indiana
Bethlehem, Pennsylvania
LaCrosse , Wisconsin
York , Pennsylvania
Quantity
(dry tons/year)
2,960
140
710
1,360
Cost
($/dry ton)
19
47
49
73
FILTERED
Quantity
(dry tons/year)
900
460
3,650
970
Cost
($/dry ton)
53
120
81
165
Weighted Average
1,292
38
1,495
93
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providing adequate sludge storage capacity at the plant. The
storage capacity usually resulted from oversized digesters or from
non-functioning digesters. While these storage facilities were
usually older, fully depreciated structures, they not only provided
flexibility for seasonal sludge disposal but also eliminated the
need for a costly sludge dewatering operation.
30
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APPENDIX
Data collection and case writing
by
R. Kent Anderson
Bruce R. Weddle
Ted Hillmer
Al Geswein
-------
ANDERSON, INDIANA
The City of Anderson, Indiana is a community of approximately
76,000 population located about 30 miles northeast of Indianapolis,
Indiana. The City's sewage treatment facility consists of a secondary
activated sludge plant incorporating post chlorination of the effluent
and anaerobic digestion of the sewage solids, followed by dewatering by
vacuum filtration or direct application of liquid sludge to nearby
farmland.
Persons Contacted
Mr. A. E. Hallinback
Superintendent
Mr. Chuck Bell
Industrial Monitoring
Department of Water Pollution Control
2801 Moss Island Road
Anderson, Indiana
Telephone (317) 646-5791
Site Description
Liquid Sludge Disposal - The City hauls liquid sludge to one of 30
different farms. Each disposal site varies in size and cropping practice
and is selected from a list of farmers requesting the addition of sludge
to their land. Because of the waiting list of farmers wanting sludge,
only one application per year is normally made. Most of the sites
receiving sludge are within 10 miles of the plant. During wet weather,
sludge is transferred to a Big Wheels at the farm for spreading.
Vacuum Filtered Sludge - The City's vacuum filtered sludge is
mainly stored on site for the public to pick up. Excess vacuum filtered
sludge is hauled to the sanitary landfill.
General Information
The City estimates that industry contributes 44 percent of the
plant flow. Most industries have pretreatment or are installing a pre-
treatment process. Major industries consist of two automotive related
plants and a meat packing plant. The population equivalent of the
plant—based on 0.17 Ibs/BOD/person/day—is 100,000. The present design
capacity is 22.7 MGD and the average daily flow is 18 MGD. The effluent
is discharged into the White River. The treatment plant is presently
undergoing reconstruction to include wet air oxidation.
All sludge leaving the plant receives secondary digestion. The
City reported that in 1974, this amounted to approximately 10,000,000
gallons at 9.3 percent solids (i.e., 10.5 dry tons/day).
33
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Sewage Sludge Composition
Table 1 presents data on the composition of the Anderson sludge.
The solids content of the liquid sludge is 9.3 percent and of the dewatered
sludge is 26.1 percent.
Transport System
Liquid Sludge - The City currently liquid hauls the majority of
its sludge. The decision to vacuum filter or liquid haul is solely
dependent upon the availability of a readily accessible field. Liquid
sludge is hauled an average of 5 1/2 days per week. The City has been
hauling liquid sludge for the past 12 years. The transport vehicles
consist of five 1,400 gallon tank trucks and one 1,500 gallon Big Wheels
for use in wet fields. The Big Wheels is only used on a farm during wet
weather for spreading sludge pumped into it from tank trucks.
In 1974, a total of 5,453 loads of sludge were hauled with an
average total haul time of 52 minutes. Five drivers and five trucks are
used approximately half time as a yearly average to haul liquid sludge.
The average round trip distance to disposal sites is about 11 miles with
an average driving time of about 25 minutes. Loading time amounts to
about 4-5 minutes and about 22 minutes to unload. The trucks are equipped
with a fan-shaped, gravity flow spreading device.
Vacuum Filtered Sludge - Because of the high cost of maintenance,
chemicals and labor to operate the vacuum filters, they are only used
when conditions are not conducive to liquid hauling and the plant cannot
store additional sludge. In 1975, the vacuum filters were only operated
one day. In 1974, the year on which our analysis is based, the vacuum
filters were operated 1,169 hours. The dried sludge is mainly stockpiled
close-by, on site for private individuals to pickup for garden use.
Excess dried sludge is hauled to the sanitary landfill. The City has
two 2 1/2 cubic yard dump trucks which are for hauling filtered sludge,
grit, and screenings.
Landspreading System
Most liquid sludge is. applied by the tank truck directly on the
fields by a gravity flow system through a fan-shaped spreader nozzle.
However, when fields are wet, the sludge is pumped from the tankers into
a Big Wheels for spreading. The Big Wheels uses a pressurized unloading
system. Because of the demand for sludge, most fields only receive one
application per year. The normal application rate is 10,000 gallons per
acre (4 dry tons/acre). The principal crops grown on land receiving
sludge are corn and soybeans. A sod farm and airport grounds also
receive liquid sludge. The City does not charge the farmers for sludge.
34
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Costs
The 1974 cost to the City for disposal of 2,960 dry tons of liquid
sludge was $19 per dry ton. In comparison, the City's cost for disposal
of 900 dry tons of vacuum dried sludge was $53 per dry ton. With the
vacuum filtered sludge, the cost of dewatering accounts for about $48
per dry ton. The major cost items for dewatering are depreciation of
the vacuum filters at about $14,730, personnel costs of over $14,000,
and chemical costs of about $5,400. A breakdown of how these costs were
determined is attached.
35
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation . $ 9,490
1970 Ford, cost: $9,148
1970 Ford, cost: $9,148
2 1973 Fords, cost: $7,800
1974 Chevy, cost: $3,898
1974 CMC Big Wheels, cost: $25,954
Total Annual Capital Cost $ 9,490
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
5 Truck Drivers $4.62 46 $21,970
Chemist 3.61 3 220
$22,190
Fringe Benefits (30 percent) $ 6,650
Vehicle-Maintenance and Operation $12,620
Utilities $ 20
TOTAL ANNUAL OPERATING COST $41,490
TOTAL ANNUAL CAPITAL AND OPERATING COST $50,980
10 PERCENT CONTINGENCY FACTOR 2 $ 5,100
TOTAL ANNUAL COST $56,080
Total Annual Cost = $56,080 = $19 per dry ton
Total Sludge Hauled Annually 2,960 dry tons
1 Vehicles were depreciated over 8 years at 8 percent interest, which
amounts to a depreciation charge of $14.14 per $1,000 per month.
2 A 10 percent contingency factor is added to cover such items as admin-
istrative overhead.
36
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COST FOR DISPOSAL OF VACUUM DRIED SLUDGE
Annual Capital Cost
Vehicle Depreciation •*• $ 320
1969 Dump Truck, cost: $4,400
1972 Dump Truck, cost: $4,952
Stationary Equipment Depreciation $14,730
Vacuum Filters, cost: $101,110
Total Annual Capital Cost $15,050
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
4 Operators $4.62 30 $11,460
Truck Driver 4.62 30 2,860
$14,320
Fringe Benefits (30 percent) $4,120
Vehicle Maintenance and Operation $ 180
Vacuum Filter Maintenance
Chemicals $ 5,390
Parts and Repair 3,500
Utilities $1,000
TOTAL ANNUAL OPERATING COST $28,516
TOTAL ANNUAL CAPITAL AND OPERATING COST $43,560
10 PERCENT CONTINGENCY FACTOR 3 $ 4,360
TOTAL ANNUAL COST $47,920
Total Annual Cost = $47,920 = $53 per dry ton
Total Sludge Hauled Annually 900 dry tons
1 Vehicles were depreciated over 8 years at 8 percent interest, which
amounts to a depreciation charge of $14.14 per $1,000 per month.
2 Stationary equipment was depreciated over 10 years at 8 percent interest,
which amounts to a depreciation charge of $12.13 per $1,000 per month.
3 A 10 percent contingency factor is added to cover such items as admin-
istrative overhead.
37
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TABLE 1
HEAVY METAL ANALYSIS ON ANDERSON DIGESTED SLUDGE
FALL 1975
2
TS
Cu
MN
ZN
CR
Pb
Fe
Ni
Cd
Mo
AL
SN
Co
Ag
Sb
As
J.
8.56
14.3501
276
9,100
11,040
1,130
16,000
1,140
255
14
28
3
NA
NA
NA
NA
NA
2
5.98
12,860
193
6,250
12,510
166
19,870
1,030
212
18
31
NA
NA
NA
NA
NA
_3
6.12
12,440
204
9,420
13,080
338
13,170
1,330
201
9
24
293
41
14
5
9
Samples
_4
5.55
10,520
146
12,940
10,320
583
15,170
2,100
162
8
29
65
32
1
5
1
_5
8.04
10,210
173
12,620
11,630
842
14,850
2,480
229
10
37
99
74
19
8
1
6
7.34
7,400
190
15,720.
8,680
579
11,000
1,740
223
7
29
116
21
12
2
1
7
7.66
6,970
170
17,040
6,080
503
8,130
1,550
170
8
23
93
39
39
1
1
All results reported in ppm dry solids
2 Total Solids
Not Analyzed
38
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APPLETON, WISCONSIN
Appleton is a community of approximately 58,000 people that is
located 100 miles north of Milwaukee, Wisconsin. The area is served
by one treatment facility which consists of a secondary activated sewage
treatment process incorporating both pre and post-chlorination, and
partial (25 percent) anaerobic digestion of the resulting solids. After
digestion, the sludge is vacuum filtered and hauled by a private con-
tractor to local farmland. Permits are required by the Lake Michigan
Department of Natural Resources before the sludge can be applied to
the land.
Persons Contacted
Mr. Wayne Colbert
Wastewater Superintendent
City Hall
225 North Oneida Street
Appleton, Wisconsin 54911
Telephone: (414) 739-4396
Mr. Richard B. Van Handel
Sludge Contractor
2435 East Edgewood Drive
Appleton, Wisconsin 54911
Telephone: (414) 734-1272
Site Description
The City's dewatered sludge is hauled by a contractor to several
different site locations for disposal. Each disposal site varies in
size and cropping practice, and is selected from a list of farmers
requesting sewage sludge for use on their land. The sludge is hauled
362 days of the year. An application of approximately eight inches
of sludge is placed on each farm per year. The soil in this area is an
Allendale loamy fine sand.
General Information
Industrial input into the City's treatment facilities was estimated
to be approximately 30 percent of the total daily flow. The design
capacity of the plant is 20 MGD for the primary stage and 12 MGD for the
secondary stage. The average daily flow is 12 MGD. The effluent is
discharged directly into the Fox River, which eventually drains into Lake
Winnobago. With the present plant design, it is obvious that this system
cannot handle peak flows. Because of this situation, the City is currently
in the midst of a plant expansion program to upgrade the total facility.
The present system of landspreading sludge will continue with the
proposed expansion.
39
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The total quantity of primary and secondary activated sludge generated
amounts to 7,700 tons per year of filter cake. The sludge comes off the
vacuum filter at 20 to 22 percent solids. The total amount of cake
leaving the plant after partial digestion is 47,680 cubic yards per year.
This partial digestion results from the fact that the digesters are old
and do not function properly. Therefore, three of the four digesters
are utilized for storage with the remaining digester operating "normally."
The reduced retention time in the operating digester results in about a
25 percent reduction of the sludge.
Based on national per capita sludge generation figures, the City of
Appleton, Wisconsin, should be generating approximately 5.2 dry tons of
solids per day. This is not the case, however. It was reported that
the City generates on the order of 21 dry tons per day. This results from
the industrial contribution (Appleton is the home of a paper mill and a
sugar beet cannery that operates six months of the year) and the plant design,
which requires the use of 1,050 tons of lime each year.
Sewage Sludge Composition
Table 1 presents data relative to the metals content of Appleton
sludge. Samples were taken by Badger Laboratories and Engineering on
September 16, 1975, and analyzed for several heavy metals. The sludge
is high in some metals (i.e., copper, lead, cadmium, and chromium).
Transport System
The method used for hauling filter cake and spreading is somewhat
unique. From the "digesters" (i.e., storage tanks), the liquid sludge
is pumped to the vacuum filters where the dewatering occurs. The cake
then drops onto a conveyor belt which takes it to an enclosed concrete
slab adjacent to the vacuum filter building. Here, a front end loader
scoops the cake from the concrete area into a dump truck. The transport
vehicles used include: one four wheel drive six by six, used on wet
fields; one Ford 5-axle, used on dry or frozen fields; one Ford dumptrailer,
used in hauling; two blade dozers used in spreading the sludge; and one
four wheel drive tractor, used in plowing the sludge under.
Landspreading System
The dewatered sludge is hauled by dump trucks to farmland, with the
driver of the dump truck also being responsible for spreading his load
with the blade dozer vehicle. After spreading of the sludge has taken place,
the sludge is plowed under, usually on the same day as the spreading.
Although there have been some complaints concerning odors before the
sludge is plowed under, the odors are minimal when compared with raw
animal manure solids that are collected, stored, and applied by farmers
40
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to their own land. All these services—hauling, dumping, spreading, and
plowing—are provided by the hauler at no cost to the farmer. However,
it is possible that in the future, some costs could be encountered by the
farmer to cover added transportation for long distance hauls.
Most of the City's sludge is being hauled to corn fields. Appli-
cations are only made after the field is cropped or before spring planting.
Of the 350 acres that are available for spreading, it is estimated that
half (175 acres) is utilized by the City of Appleton to dispose of their
sludge, with the remainder of the acreage being used by the City of
Neenah-Menasha. Based on figures provided by the plant, it can be
calculated that the Appleton area farmers receive 44 dry tons per acre
per year. Crop yields on fields which had received sludge that year
were reduced, apparently because of the high metals content of the sludge
and also its high pH, caused by the large lime content. Two years after
a one-time application of sludge, crop yields were dramatically increased.
Cost
Based on actual operating information provided by representatives of
Appleton, the City was disposing of its sludge in 1974 at a cost of $42
per dry ton of solids, with operating time of the vacuum filter being 16
hours a day, 7 days a week. Of this, the cost of dewatering amounted to
about $25 per dry ton. Major costs items for dewatering included chemicals,
which cost over $70,000, and personnel, nearly $47,000. The contractor cost
was $2.25 per yard hauled in 1974. However, in 1975, the cost rose to
$4.00 per yard hauled. This would increase the disposal cost to $54 per
dry ton of solids. A more detailed cost breakdown of the variable and
fixed costs is attached.
41
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COST FOR DISPOSAL OF VACUUM FILTERED SLUDGE
Annual Capital Cost
Vehicle Depreciation 0
Plant Equipment Depreciation 0
Total Annual Capital Cost
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Vacuum Filter Operator $5.00 100 $10,400
Vacuum Filter Operator 5.30 100 11,020
2 Lime Room Laborers 4.86 100 20,220
Assistant Superintendent 6.15 30 3,840
Superintendent 6.97 10 1,450
$46,930
Fringe Benefits at 30 percent $14,080
Vacuum Filter Operation and Maintenance
Chemicals
Lime $46,980
Ferric Chloride 25,420
Acid 1,240
Parts and Repair 21,300
Vehicle Operation and Maintenance
Contract Hauling (@ $2.25 per yard) $107,220
Utilities (gas and water) $33,240
TOTAL ANNUAL OPERATING COST $296,410
TOTAL ANNUAL CAPITAL AND OPERATING COST $296,410
10 PERCENT CONTINGENCY FACTOR1 29,640
TOTAL ANNUAL COST $326,050
Total Annual Cost = $326,050 = $42 per dry ton
Total Sludge Hauled Annually 7,700 dry tons
1 A 10 percent contingency factor is added to cover such items as
administrative overhead.
42
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TABLE 1
Sludge Sample Taken September 16, 1975
Badger Laboratories and Engineering
Stephen Taylor, Chief Chemist
Percent Solids 18.6 %
Percent Ammonia Nitrogen 0.11%
Organic Nitrogen 2.70%
Percent Total Nitrogen 2.81%
Phosphorus 2,916 ppm
Potassium 123.1 ppm
Chromium 734.9 ppm
Copper 534.6 ppm
Lead 764.1 ppm
Zinc 70.2 ppm
Cadmium 111.2 ppm
Mercury 0.011 ppm
Nickel 88.0 ppm
Figures are reported on a dry weight basis
43
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BELLEVILLE, ILLINOIS
The City of Belleville, Illinois is a community of approximately
41,700 population, located 15 miles southeast of St. Louis, Missouri. The
City's largest sewage treatment facility consists of a secondary activated
sludge plant incorporating post chlorination of the effluent and anaerobic
digestion of the sewage solids, followed by air drying and/or direct applica-
tion of liquid sludge to nearby farmland.
Person Contacted
Mr. George Hankammer
Superintendent of Treatment
Plant Operations
Belleville, Illinois 62220
Telephone: (618) 233-6810
Site Description
Liquid Sludge Disposal - The City hauls liquid sludge to one of several
different site locations. Each disposal site varies in size and cropping
practice and is selected from a list of farmers requesting the addition
of sludge to their land. Any farmer within a reasonable haul distance
(i.e./ 5-10 miles) who desires to have sludge placed on his land may place
a request with the City and if conditions are suitable (i.e., weather, sea-
son of the year, site accessibility, etc.) the wastewater treatment plant
will make one or two applications of sewage sludge to his land.
Air Dried Sludge - The City's air dried sludge is stored in a small
designated area adjacent to the main treatment plant property. The area
is located just outside a fenced area that surrounds the plant, thus enabling
persons desiring the sludge to pick it up at their leisure. No regula-
tion or other controls are placed upon the use or the amount of sludge an
individual may take. According to one City official, "the pile just seems
to gradually erode away."
General Information
The City Superintendent of Treatment Plant Operations estimated the
industrial input into the City's treatment facilities to be approximately
40 percent of the total flow. The population equivalent, based on a BOD of
0.17 Ibs BOD/cap/day, is calculated at 76,000. The overall treatment plant
design capacity is rated at 6.0 MGD with an average flow of 5.5 MGD. The
effluent is discharged directly into a very small stream that drains into
the Kaskaskia River.
The plant effluent often exceeds the normal stream flow in the creek.
To improve the effluent quality, the City is currently in the midst of
44
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upgrading the facility to include tertiary treatment. After completion,
the City intends to dispose of its sludge by dewatering with a centrifuge
and stockpiling the sludge for citizens to remove. The centrifuge is
scheduled to come on line shortly after January 1, 1976.
The combined quantity of primary and secondary activitated sludge
generated today totals approximately 33,000 gallons/day at 4.3 percent
solids (i.e., 5.9 dry tons/day). The total sludge leaving the plant
after digestion averages 15,000 gallons/day at 3.8 percent solids
(i.e., 2.4 dry tons/day or 880 dry tons/year). This represents a 60
percent reduction in total solids generated. This is an extremely high
reduction in solids content as digestion typically results in only a 35
to 40 percent reduction in solids. It can be explained by the somewhat
unique nature of the industrial contributors (i.e., slaughterhouse
waste, brewery plant, hospital, and a paper box manufacturer). Based on
the type of treatment provided, a more reasonable estimate as to the
total solids disposed annually in the City of Belleville should be 1,000
dry tons/year, or approximately .14 Ibs/cap/day.
Sewage Sludge Composition
Table 1 presents data on the metals content of the liquid sludge.
Samples were taken from one of the two large secondary digesters on
January 14, 1974 and analyzed for a comprehensive list of heavy metals.
As displayed, the sludge is fairly low in all metals. This is probably
due to the fact that the industrial contributors are not major heavy
metal polluters. One possible exception is a relatively large enamelling
plant. However, no specific data as to the amount or characteristics of
the industrial waste from this plant were available.
Transport System
Liquid Sludge - The City currently liquid hauls half of its sludge
and has been doing so for the past five or six years. The decision to
air dry or liquid haul is solely predicated upon the availability of a
readily accessible field, weather conditions, season of the year, and
the haul distance to the site. In general the City liquid hauls its
sludge at 3.8 percent solids 10 to 12 weeks out of the year. The
transport vehicles consist of two 2,000 gallon tank trucks. One was
purchased in 1971 at a cost of $9,000 and the other is a 1966 vehicle
purchased at a cost of $6,000.
It was reported that on days that sludge is hauled an average of 20
loads of liquid sludge are removed from the plant. Two drivers and two
vehicles are used essentially full time during the periods when sludge
is liquid hauled (i.e., early spring and late fall). The average haul
distance is approximately six miles one way with an average round trip
driving time of 20 minutes. The vehicles take approximately 10 minutes
to load and 15 minutes to unload. They are not equipped with a pump,
spreading "T" or any other device to aid spreading or distribution
capability. The City's two large anaerobic digesters are used for
storage (i.e., 1.7 million gallon combined capacity).
45
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Air Dried - The only transport system involved in handling the air
dried sludge is a 1966, 1 1/2 ton Ford dump truck with a three cubic yard
body purchased at a cost of $2,800. There is no significant haul time
involved, as the vehicle is loaded and then only travels several hundred
feet before it offloads.
The air drying beds collectively encompass an area of 2.75 acres of
actual drying surface and include an additional 2.25 acres of miscellaneous
area (i.e., roadways, green area, etc.). Each drying bed holds a maximum
of 100,000 gallons of sludge at 4 percent solids (i.e., 15 dry tons of
solids or about one weeks worth of sludge) . Each of the 11 individual
drying beds are covered at least three times each year. The land was pur-
chased in 1942 at a value of approximately $40/acre. No information was
obtained relative to the actual cost of constructing the air drying beds.
Landspreading System
Liquid Sludge - The liquid sludge is applied by gravity flow directly
from the rear of the truck. The City has experimented with pumps and hoses
but found it easier and more appealing to the driver to simply let the sludge
drain out onto the ground. Each 2,000 gallon load covers an area of 2500
to 3000 square feet which results in an application rate of five to six
dry tons per acre (i.e., 1000 feet long by 2 1/2 to 3 feet wide)- No problems
of odors or flies were noted, even though the sludge is not always turned
under immediately after application. The farmer usually turns the sludge
into the soil at no cost to the City after the field has been fully covered.
The City has been and is currently hauling most of its liquid sludge
to corn and soybean fields. Applications are only made after the field
is cropped or before the spring planting. There have been several overtures
to the City to haul its sludge to an abandoned strip mined area northeast
of the City. However, because of the excessive cost and haul distance, no
further progress has been made in the area.
Cost
The City currently employs 22 fulltime employees at its main treat-
ment plant. The total operating budget for 1974 amounted to $325,549. The
salaries and wages accounted for over 65 percent of the annual operating
cost.
The City is currently disposing of its sludge at an average cost of
$29 per ton of dry solids. The air drying operation is the more costly
of the two systems (i.e., air drying and liquid haul) because of the added
cost of dewatering and the labor intensive cleaning operation to remove
the sludge from the drying beds. It is estimated that the air drying
system (excluding the capital and maintenance cost of the drying beds) cost
the city $34 per ton of dry solids disposed. The liquid haul and spread
operation appears to be the least costly of the two systems, accounting
for only $24 per dry ton of solids disposed. A more detailed cost break-
down of the capital and operating costs for each option follows.
46
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COST FOR DISPOSAL dF AIR DRIED SLUDGE
Annual Capital Cost
Vehicle Depreciation 0
Equipment Depreciation 0
Total Annual Capital Cost 0
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Equipment Operator $5.60 20 $2,330
Laborer 4.77 20 1,980
STP Operator 5.40 11 1,240
Foreman 6.25 0.8 100
$7,630
Fringe Benefits at 25 percent $1,910
Vehicle Maintenance and Operation
Repairs $1,420
Fuel, Oil, and Insurance 950
$2,370
Utilities and Other
Electricity $ 100
Pumps, Motors and Misc. Equipment 210
Supplies (chemical polymers) 3,960
Maintenance on Beds 300
$4,570
TOTAL ANNUAL OPERATING COST $16,480
TOTAL ANNUAL CAPITAL AND OPERATING COST $16,480
10% CONTINGENCY FACTOR1 $ 1,650
TOTAL ANNUAL COST $17,130
Total Annual Cost = $17,130 = $34 per dry ton
Total Sludge Hauled Annually 500 dry tons
1 A 10 percent contingency factor is added to cover such items as
administrative overhead.
47
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation \ $2,550
1969 Ford: Cost, $6,000
1971 Ford: Cost, $9,000
Total Annual Capital Cost $ 2,550
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Truck driver $5.25 36 $3,930
Superintendent 6.25 0.5 650
Fringe Benefits at 25 percent $1,150
Vehicle Maintenance and Operation
Repairs $1,420
Gasoline, Oil, and Insurance 950
$2,370
Utilities and Other
Electrical Power $ 100
Pumps, Motors and Misc. Equipment 210
TOTAL ANNUAL OPERATING COST $ 8,310
TOTAL ANNUAL CAPITAL AND OPERATING COST $10,960
10% CONTINGENCY FACTOR 2 $ 1,100
TOTAL ANNUAL COST $12,060
Total Annual Cost = $12,060 = $24 per dry ton
Total Sludge Hauled Annually 500 dry tons
1 Vehicles were depreciated over 8 years at 8% interest which amounts
to a depreciation charge of $14.14 per $1000 per month.
2 A 10% contingency factor is added to cover such items as administrative
overhead.
48
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Table I
Sludge Sample*
January 14, 1974 - Compiled by Peabody Company
pH -
Total solids -
Volatile solids -
Kjeldahl N -
Ammonia (NH ) -
Organic N -
NO -
Total N -
SO -
Cl -
Br -
Fl -
Hardness -
Acidity -
Alkalinity -
COD -
Ca -
Mg -
Na -
Phosphorous -
K -
Al -
Cu -
Ni -
Mn
Fe -
Zn -
Cd -
Cr -
Pb -
Hg
7.2
5.58%
2.64%
7.7%
2.9%
4.8%
0%
7.7%
0 ppm
8,600 ppm
54 ppm
52 ppm
896,060 pppm as CaCo3
16,880 ppm as CaCO-j
324,190 ppm as CaC03
400,140 ppm
20,660 ppm
7,490 ppm
3,570 ppm
6,990 ppm
2,220 ppm
5,380 ppm
290 ppm
270 ppm
900 ppm
33,510 ppm
1,300 ppm
10.7 ppm
2.5 ppm
1,340 ppm
3.0 ppm
*0n a dry weight basis
49
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BETHLEHEM, PENNSYLVANIA
Bethlehem, Pennsylvania is located on the eastern border of the State
approximately 60 miles north of Philadelphia. The City wastewater
treatment plant utilizes anaerobic digestion and serves a population of
100,000. Sewage solids from the plant are transported in both the liquid
and vacuum filtered form to either farmland or to a sanitary landfill.
Person Contacted
Mr. William H. Grim
Superintendent of Wastewater Treatment
Department of Public Works
10 East Church Street
Bethlehem, Pennsylvania 18018
Telephone: (215) 865-7168
Site Description
s
Over the past seven years of landspreading, approximately 1500 acres
of farmland east of the City have received sludge. However, no records
were kept showing which land had received sludge, nor the quantities applied.
General Information
The wastewater treatment plant was constructed in 1952 and has a
design capacity of 12.5 MGD. The present average daily flow is 12.0 MGD.
Industry contributes about 40 percent of this flow. The primary industrial
contributors are a textile mill, a hospital, three metal plating plants, a
dextrose manufacturer, and several commercial laundries. Wastes from the
dextrose plant and commercial laundries cause some problems in the operation
of the plant (from grease and high solids content in their wastes). although
these are not serious. Two of the three metal platers pretreat their wastes.
After being anaerobically digested the City's sewage sludge is hauled
directly to land as a liquid at 4.5 percent solids or vacuum filtered to
20 to 25 percent solids and hauled by dump truck to the City's landfill or
to farmland. The total dry weight of sludge leaving the plant in 1974 was
600 dry tons. Of this, 140 dry tons were applied as a liquid and 460 dry
tons were dumped and spread as vacuum filtered sludge.
Sewage Sludge Composition
No sludge analysis was available.
Transport System
The vacuum filtered sludge is generally hauled to a sanitary landfill
five miles from the plant. On occasion, however, it is hauled to farmland
if there is a site available. All liquid sludge is applied to farmland.
50
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The average round trip distance to the landspreading site is nine miles
while it is 10 miles round trip distance to the sanitary landfill. The
average round trip travel time to both sites is 30 minutes. The
apparatus for loading the trucks consists of a belt conveyor from the
vacuum filters to the dump truck and a gravity flow stand pipe for the
liquid sludge.
Landspreading System
Liquid Sludge - Liquid sludge is transported and applied to farmland
by a 2,000 gallon tank truck. The truck is equipped with a "T" distribution
pipe for unloading by gravity flow while being driven across the field.
The average time for unloading the truck is 9 minutes. Because no
records are kept of the acreage receiving sludge nor the frequency of
application, it is not possible to determine the application rate. At
the time of the visit, farmers were not eager to receive sludge because
of a recent Pennsylvania State University study which pointed out
potential problems with sewage sludge due to heavy metals.
Vacuum Filtered - Most of the vacuum filtered sludge was hauled to
the sanitary landfill. However, when farmland is available, it is normally
dumped in a corner of the field for the farmer to distribute with his
manure spreader. If crops are not on the fields, the sludge is dumped in
piles across the field for the farmer to spread with a blade.
Cost
Based on actual operating information provided by the City, the 1974
cost for liquid sludge disposal was $47 per dry ton and for vacuum filtered
sludge was $120 per dry ton. With the vacuum filtered sludge, the cost of
dewatering accounts for nearly $110 per dry ton. The major reasons for high
dewatering cost are that repairs on the older vacuum filters cost about
$25,000 and labor to operate them costs over $16,000. A more detailed cost
analysis is presented on the following pages.
51
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation $1,650
1969 Ford tank truck, Cost: $9,460
Stationary Equipment Depreciation 0
Building Depreciation 0
Total Annual Capital Cost $1,650
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Truck driver $3.31 15 $1,030
Auto Mechanic 5.00 1 100
Chief Operator 6.38 6 830
Superintendent 7.93 3 500
Total Personnel Cost $2,460
Fringe Benefits at 44 percent $1,080
Vehicle Maintenance and Operation:
Repairs $ 390
Fuel and Oil 230
Insurance 130
Utilities 0
TOTAL ANNUAL OPERATING COST $4,290
TOTAL ANNUAL CAPITAL AND OPERATING COST $5,940
10% CONTINGENCY FACTOR2 $ 590
TOTAL ANNUAL COST $6,530
Total Annual Cost = $6,530 = $47/dry ton
Total Sludge Hauled Annually 140 dry tons
1 Vehicles were depreciated over 8 years at 8% interest which
amounts to a depreciation charge of $14.14 per $1000 per month.
2 A 10% contingency factor is added to cover such items as administrative
overhead.
52
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COST FOR DISPOSAL OF -VACUUM FILTERED SLUDGE
Annual Capital Cost
Vehicle Depreciation 1 $ 0
Equipment Depreciation 2 0
Building Depreciation 0
Total Annual Capital Cost $ 0
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
2 Vacuum
Filter Operators $4.08 41 $ 8,560
Clean up 3.31 15 1,030
Truck Driver 3.31 30 2,060
Auto Mechanic 5.00 3 290
Chief Operator 6.38 19 2,490
Superintendent 7.93 2 330
Total Personnel Cost $14,760
Fringe Benefits at 44 percent 6,500
Vehicle Maintenance and Operation
Repairs 550
Fuel and Oil 240
Insurance 260
Vacuum Filter Maintenance
Chemicals 1,360
Parts and repair 25,000
1 Vehicles were depreciated over 8 years at 8% interest which amounts
to a depreciation charge of $14.14 per $1000 per month.
2 Stationary equipment was depreciated over 10 years at 8% interest which
amounts to a depreciation charge of $12.13 per $1000 per month.
3 Buildings were depreciated over 20 years at 8% interest which
amounts to a depreciation charge of $8.36 per $1000 per month.
53
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Utilities 1,600
TOTAL ANNUAL OPERATING COST $50,270
TOTAL ANNUAL CAPITAL AND OPERATING COST $50,270
10% CONTINGENCY FACTOR 4 $ 5,030
TOTAL ANNUAL COST $55,300
Total Annual Cost = $55,300 = $120/dry ton
Total Sludge Hauled Annually 460 dry ton
4 A 10% contingency factor is added to cover such items as
administrative overhead.
54
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COLLINSVILLE, ILLINOIS
The City of Collinsville, Illinois is a community of approximately
20,000 population located 10 miles east of St. Louis, Missouri. The
City's wastewater treatment facility consists of a tertiary system with
post chlorination of the effluent and secondary aerobic digestion of the
sewage solids. Digested sludge is stored in ponds awaiting application
to farmland.
Person Contacted
Mr. Francis Vacca, Superintendent
Wastewater Control Plant
300 Simpson Street
Collinsville, Illinois 62234
Telephone: (618) 344-0304
Site Description
The City hauls liquid sludge to several different site locations.
Each disposal site varies in size and cropping practice and is selected
from a list of farmers requesting the addition of sludge to their land.
The farmers who now receive sludge are located adjacent to the wastewater
treatment facility. There are ten farm plots totaling 199 acres, that
range in size from 8 to 31 acre's of available land. In the future, the
superintendent plans to haul to any farmer located within a five mile
haul distance.
General Information
The City superintendent of treatment plant operations estimated the
industrial input into the City's treatment facilities to be about one
percent of the total flow. The overall treatment plant design capacity
is rated at 3.5 mgd with an average daily flow of only 1.2 mgd. The
effluent is discharged directly into a small stream - Canteen Creek -
which drains into the Mississippi River. In 1972, the City constructed
its present facility incorporating tertiary treatment with aerobic
digestion.
The combined quantities of primary and secondary activated sludge
totals 540 dry tons per year. The sludge is pumped to one of several
holding ponds prior to being transported and applied by a Big Wheels
tank truck.
Sewage Sludge Composition
Table 1 presents data relative to the metals content of Collinsville
sludge. As displayed, the sludge is fairly low in metals except iron
(i.e., 27,148 ppm). This is probably due to infiltration into the
collection system, street runoff, and ground runoff from the rocky hills
around the area.
55
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Transport System
The City currently liquid hauls all of its digested sludge. The
limitation of when one can haul has been greatly minimized due to the
purchase of a Big Wheels vehicle. The Big Wheels vehicle, which con-
sists of a 1600 gallon tank on a CMC chassis is equipped with high
flotation terra-tires that virtually eliminate the traditional problems
of ruts, compacted soil, and crop damage. The vehicle was purchased in
1975 at a cost of $35,000.
It was reported that an average of 13 loads per month of liquid
sludge at 8 to 10 percent solids is hauled from the plant. The average
haul distance is one mile and the load and unload time are both five
minutes. The truck is loaded by utilizing a pump on the truck to pump
the sludge from the two ponds which hold 960,000 gallons. With this
short haul distance, as many as 15 loads per day can be handled by the
truck. As a result, all the sludge produced at the plant can be hauled
in an average of one day per month. On haul days, two drivers are
utilized, one working 80 percent of the time and the other 20 percent.
Landspreading System
The City has experimented with various systems and private contract-
ors but has found it easier and more appealing to utilize the Big Wheels.
This truck is equipped with a pressurized rear spray system with each
load covering an area of 25 to 30 feet by 1000 feet. Sludge is applied
at a rate of about one dry ton per acre. In some cases two or three
applications will be made per year. The sludge is turned under by the
farmer within 24 hours of application. There have not been any problems
with odors or flies. To date, sludge has been applied to wheat and
soybean fields.
Cost
The City currently has seven fulltime employees at the treatment
facility. The total operating budget for the sewage collection system
and the treatment plant is $270,000.
It is difficult to develop realistic costs on this system because
the new treatment plant has only been in operation a short period, and
they do not haul all the sludge that is currently being produced. The
lagoons which are used to store the digested sludge are new and there-
fore can be utilized as a holding area until they reach maximum capacity.
During this storage process the liquid from the lagoon is recirculated
to the front of the plant. Furthermore, a portion of the water evapor-
ates. Thus when the sludge is pumped from the lagoon to the vehicle,
the percentage of solids has increased from 3 to 4 percent to approximately
8 to 10 percent.
56
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Because the City is stockpiling a portion of its sludge/ any cost
analysis based on only the amount actually being hauled would be very
misleading. Therefore this analysis is based on the City hauling their
entire sludge production of 540 dry tons (which the City will be hauling
once the lagoons are filled).
Based on information provided by the City of Collinsville and
vehicle maintenance and operational costs provided by the truck manu-
facturers, the City's cost for disposing of its total annual sludge
quantity (excluding the costs of the lagoons) is $34 per dry ton.
57
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation * $ 5,940
1975, CMC - Big Wheels, cost: $35,000
Total Annual Capital Cost $ 5,940
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Driver
Driver"s
Assistant
Chemist
Secretary
Superintendent
$5.31
5.31
5.41
2.50
5.70
3 percent
and Operation:
40 $ 4,420
10 1,100
2 240
2 100
5 590
$ 6,450
$ 2,130
$ 1,170
140
320
600
Gasoline
Oil
Insurance
Maintenance
$ 2,230
TOTAL ANNUAL OPERATING COST $10,810
TOTAL ANNUAL CAPITAL AND OPERATING COST $16,710
10% CONTINGENCY FACTOR 2 $ 1,680
TOTAL ANNUAL COST $18,430
Total Annual Cost = $18,430 = $34 per dry ton
Total Sludge Hauled Annually 540 dry tons
1 Vehicles were depreciated over 8 years at 8% interest which
amounts to a depreciation charge of $14.14 per $1000 per month.
2 A 10% contingency factor is added to cover such items as
administrative overhead.
58
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TABLE 1
SLUDGE ANALYSIS *
Barium 479 ppm
Cadmium 16 ppm
Chromium, Trivalent 64 ppm
Copper 260 ppm
Lead 345 ppm
Manganese 701 ppm
Nickel 58 ppm
Silver 34 ppm
Zinc 1,585 ppm
Chromium 0.06 ppm
Mercury 0.06 ppm
Iron 27,149 ppm
Ammonia as N 9,173 ppm
Organic Nitrogen 24,606 ppm
Boron 157 ppm
Alkalinity as CaC03 93,240 ppm
pH 7.86
Volatile Solids 6.49 %
Total Phosphorus as P 14,896 ppm
Total Solids in Sample 17.94 %
Volatile Solids in Sample 6.49 %
* On a dry weight basis
59
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DANVILLE, VIRGINIA
The City of Danville, Virginia is a community of approximately
49,000 population located,50 miles north of Greensboro, North Carolina.
The City's Southside Wastewater Pollution Control Facility consists of a
secondary extended aeration process incorporating post-chlorination of
the effluent. The settleable solids are thickened and placed in storage
tanks, without stabilization, until the liquid sludge can be applied on
nearby farmland.
Person Contacted
Mr. Jerry W. Harris
Assistant Chief of Operations
Water, Gas and Electric Departments
460 Williamson Road
Danville, Virginia 24541
Telephone: (804) 799-5153
Site Description
The City is presently utilizing 19 farms having a collective acreage
of approximately 4,200 acres. Each site varies in size and cropping
practice and is selected from a list of farmers requesting the addition
of raw sludge to their land. Any farmer within a haul distance of 9
miles who desires to have sludge placed on his land may place a request
with the City and if conditions are favorable (i.e., weather, season of
the year, site accessibility, etc.), the sewage treatment plant will
make one to four applications of sludge to his land per year. It is the
policy of the treatment plant to spread sludge only on land which is not
directly used to grow crops for human consumption. However, sludge has
been applied to pasture land, fodder crops and tobacco.
General Information
The City estimated the industrial input to the Southside Wastewater
Pollution Control Facility to be approximately 40 percent of the total
flow. Industrial contribution to the sewage treatment plant is mainly
from Goodyear Tire Company (the largest Goodyear plant in the U.S.),
Porter-Disston tool, Dan River Mills (largest textile plant in the U.S.),
and Corning Glass Company. Both Porter-Disston and Corning Glass pretreat
their effluent. The population equivalent, based on 0.17 Ibs BOD/cap/day
is 63,870. The total amount of sludge leaving the Wastewater treatment
plant was 1490 dry tons in 1974 or 0.17 Ibs/cap/day. This per capita
figure is low because of the high industrial flow which is very low in
solids. The overall treatment plant design capacity is rated at 15 MGD
with an average daily flow of 10.5 MGD. The treatment plant is an
activated sludge plant with two parallel aeration basins. Sludge from
the clarifiers is piped to thickeners and stored in two unusable digesters
until it is trucked to various farms in the area.
60
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The secondary treatment facility was put on line in 1969. In 1973,
construction began on a new secondary plant across the river from the
existing plant, with a design capacity of 24 MGD. The new plant, which
is scheduled for completion in 1976, will handle primarily the Dan River
Mills' (textile) influent. The mill is presently discharging 60 percent
of its waste in the Dan River. Following the completion of the new
wastewater facility, sludge from the existing plant will be piped across
the river to the new plant where it will be heat dried and hauled in
dump trucks to farmland. This will be disced under upon application by
the individual land owner.
There does not seem to be any problem with public acceptability of
the sludge spreading practice. In fact, many farmers in Virginia and
North Carolina within a radius of approximately 9 miles of the treatment
plant have received and would like to continue receiving sludge. However,
at the time of the visit, sludge was only being hauled to Virginia
because the North Carolina State Public Health Service decided to
further evaluate the effects of the raw sludge before approving further
landspreading.
Sewage Sludge Composition
Analyses have been performed on the sludge by a private consulting
firm (see Table 1).
Transport System
Currently, the City hauls all of the sludge to nearby farmland at
2.7 to 3.6 percent solids every week of the year. The City has been
hauling liquid sludge for the past 13 years. The transport vehicles
consist of 1974 deisel-tandem wheel Auto Car (4,600 gallons), purchased
at a cost of $39,500 and a 1974 diesel-tandem wheel Auto Car (4,600
gallons), purchased at a cost of $45,000.
It was reported that an average of 14 loads per day is hauled from
the plant. Two drivers and two vehicles are used essentially full time
during the periods when sludge is hauled. The trucks are equipped with
pumps and spreader devices and require approximately 10 minutes to load
and 10 minutes to unload.
Landspreading System
The liquid sludge is spread by a pressure system from the side of
the vehicles. Each load covers a different area depending on the vehicle:
1974 Auto Car, 1-1/2" discharge pipe which gives a 35 ft. spread of
sludge, 1,800 gallons per acre, 500 Ibs per acre dry weight at 3.5
percent solids; and, 1974 Auto Car, using a 1-1/4" pipe sprays approxi-
mately 50 ft., 1,800 gallons per acre, 500 Ibs per acre dry weight at
61
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3.5 percent solids. During wet weather periods when fields are un-
accessible, the city spreads liquid sludge from the sides of the paved
runway located at Danville's City Airport. The City makes four appli-
cations to each site. No problems of odors or flies were noted, even
though the sludge is not always turned under immediately after appli-
cation.
Cost
Based on actual operating information provided by the City of
Danville, current cost for disposing of the City's sludge is $22 per dry
ton. A more detailed cost analysis follows.
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation3-
1974 Auto Car Cost: $39,500 $ 6,700
1974 Auto Car Cost: $45,000 $ 7,640
Equipment Depreciation
Standing Pipe 20
Total Annual Capital Cost $14,360
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Driver $3.25 60 $4,060
Driver 3.25 60 4,060
Lab Technician 4.11 5 430
Chief Operator 5.76 10 1,200
$9,750
Fringe Benefits at 28 percent $2,730
Vehicle Maintenance and Operation
(estimated) $2,400
Utilities
Electricity at $100 per month $1,200
TOTAL ANNUAL OPERATING COST $16,080
TOTAL ANNUAL CAPITAL AND OPERATING COST $30,440
10% CONTINGENCY FACTOR3 $ 3,040
TOTAL ANNUAL COST $33,480
Total Annual Cost = $33,480 = $22 per dry ton
Total Sludge Hauled Annually 1,490 dry tons
1 Vehicles were depreciated over 8 years at 8% interest which
amounts to a depreciation charge of $14.14 per $1000 per month.
2 Stationary equipment was depreciated over 10 years at 8% interest
which amounts to a depreciation charge of $12.13 per $1000 per month.
3 A 10% contingency factor is added to cover such items as
administrative overhead.
63
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Table I
Danville, Virginia Sludge
SCS Engineers, Consultant*
Parameter ppM
Cadmium __
^ «7 • /
247.0
Nickel
178.0
350.0
*Analysis made on A.A.
Dry Weight Basis
64
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FT. PIERCE, FLORIDA
Ft. Pierce, Florida, is a community of approximately 32,000 popu-
lation located 70 miles due north of West Palm Beach. The City's
wastewater treatment facility consists of a "standard" secondary acti-
vated sludge plant and a package secondary activated sludge plant (i.e.,
a small individual plant). Both plants stabilize the settleable solids
by aerobic digestion, followed by post-chlorination of the effluent.
Ultimately, the effluent is discharged into the Indian River, while the
sludge is utilized on farmland.
Person Contacted
Mr. Richard Kasch
Wastewater Treatment Plant
Seaway Drive
Ft. Pierce, Florida 33450
Telephone: (305) 464-1996
Site Description
Of the total sludge generated, 95 percent is hauled in the liquid
state to farmland owned by the Future Farmers of America (FFA) of Ft.
Pierce, with the remainder being transported to other farms in the area.
The FFA farmland, consisting of some 600 acres of available land for
disposal of sludge, is fenced off into small parcels for the purpose of
ongoing research. The terrain is flat—less than 1 percent slope—with
a sandy-loam soil.
To obtain the City's remaining sludge, interested citizens contact
the plant superintendent. When conditions are such that the driver is
unable to traverse the FFA land (e.g., heavy rainfall periods, early
spring, etc.), the City will haul sludge to other sites which are
predominately used for grazing.
General Information
The City's superintendent of wastewater operations estimated the
industrial input (from such contributors as citrus and tomato processors,
a commercial laundry, and the seasonal tourist trade establishments)
into the City's main facility and package plant to be approximately
10 percent of the total flow. The package plant receives 30 percent
of the total influent and is equipped with a contact stabilization
chamber, an aerobic digester, and a pre-chlorination tank. Although
the average daily flow of the total system is 3.5 MGD, the overall
treatment plant design capacity is rated at 5.0 MGD. The population
served by the system is 32,000 with a population equivalent of 33,400
based on a BOD of 0.17 Ibs/cap/day.
65
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Although the average amount of sludge hauled from the main plant
and the package plant on a daily basis equals approximately 10,000
gallons at 2.4 percent solids, seasonal variations are large. Sludge
hauled from the plants in 1974-75 amounted to approximately 390 dry tons
per year, or 0.07 Ibs/cap/day. For the type of treatment employed, this
figure is very low. This is apparently due to operational problems
experienced by the plants.
Sewage Sludge Composition
No sludge analysis was available.
Transport System
Ft. Pierce hauls all of its digested sludge as a liquid at less
than 3 percent solids and usually does so 52 weeks of the year. Trans-
porting sludge by tank truck has taken place for the last 1 1/2 years,
and the present transport vehicles include two 2,200-gallon tank trucks.
One truck, a 1971 International, was purchased in 1971 at a cost of
$8,790; the other vehicle, a 1974 International, was purchased at a cost
of $9,820.
It was reported that an average of 35 loads of liquid sludge per
week are hauled from the plant by two drivers. One driver works 90
percent of his time on sludge-hauling operations; and the other works
during the peak tourist trade season (approximately 40 percent of the
year). With a one-way haul distance of approximately 15 miles, the
average round-trip driving time is 50 to 60 minutes. In addition, it
takes approximately 10 minutes to load the sludge and 10 minutes to
unload it at each site.
Landspreading System
Liquid sludge is applied by gravity flow directly from a pipe at
the rear of the truck. A spreading device is not utilized on these
trucks. Each load covers an area of 5,000 to 6,000 square feet (2,000
feet long x 2 1/2 to 3 feet wide). The application rate is approxi-
mately 2.4 dry tons of solids per acre per application. In instances in
which two to three applications are made, as much as 5 to 7 1/2 tons of
dry solids may be applied. Even though the sludge is never turned under
after application, no problems of odors or flies have been noted.
Cost
Based on actual operating information provided by the City of Ft.
Pierce, the current cost for disposing of its sludge is $81 per ton of
dry solids. This high figure is primarily the result of a long haul
distance and the $5,000 fee charged each year by the FFA for sludge
disposal on its land. A more detailed cost analysis follows.
66
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation $ 3,160
1971 International, Cost: $8,790
1974 International, Cost: $9,800
Total Annual Capital Cost $ 3,160
Annual Operating Cost
Personnel
Driver
Driver
Lab Tech-
nician
Superin-
tendent
Overtime
Fringe Benefits at
Vehicle Operation
Gasoline
Oil
Insurance
Truck License
Hourly Rate %
$3.18
$3.18
$4.67
$6.72
38 percent
and Maintenance:
fees
Maintenance and Repair
Time Worked Cost
90 5,950
40 2,650
5 490
5 700
230
$10,020
$ 3,810
1,980
70
690
10
4,370
$ 5,120
TOTAL ANNUAL OPERATING COST - $20,950
TOTAL ANNUAL CAPITAL AND OPERATING COST $24,110
10% CONTINGENCY FACTOR2 $ 2,411
COST FOR DISPOSAL ON FFA LAND $ 5,000
TOTAL ANNUAL COST $31,520
Total Annual Cost = $31,520 = $81 per dry ton
Total Sludge Hauled Annually 390 dry tons
1 Vehicles were depreciated over 8 years at 8% interest which
amounts to a depreciation charge of $14.14 per $1000 per month.
2 A 10% contingency factor is added to cover such items as
administrative overhead.
67
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FRONT ROYAL, VIRGINIA
This community of approximately 9500 population is located 60 miles
southwest of Washington, D.C. The City's sewage treatment facility
consists of a primary plant incorporating post-chlorination of the
effluent and anaerobic digestion of the sewage solids followed by air
drying and/or direct application of liquid sludge to farmland adjacent
to the treatment plant.
Person Contacted
Mr. C.H. Williams
Superintendent of Water and Wastewater
Box 1560
Front Royal, Virginia 22630
Telephone: (703) 635-3552
Site Description
Sewage sludge is applied primarily on 15 acres of City owne"d land.
It is also applied to a large nearby farm when cropping conditions dd
not permit application to the City properly.
General Information
The treatment plant was constructed in 1950 and consists of primary
treatment with a 1.5 MGD design capacity. The average daily flow is 1.2
MGD. Presently, the plant treats only domestic waste. (There is a
large FMC plant in town but it does not discharge into the municipal
system.) The City of Front Royal is reviewing plans for a new plant to
be constructed in 1977 adjacent to the old plant. It intends to continue
its landspreading operation and expects to purchase a new tank truck.
The sludge is anaerobically digested and thickened with enzymes and
lime. The resulting solids content is reported to be approximately 15
percent. The City generates approximately 18,000 gallons of sludge per
month, (i.e. 10-12 dry tons per month).
Sewage Sludge Composition
No sludge analysis was available.
Transport System
The City transports its sludge in a 1947 International truck
equipped with a 1500 gallon tank. The vehicle was purchased in
1956 at a cost of $300. The haul distance from the loading area to
the primary disposal site is approximately 1/4 of a mile. Because the
vehicle is not operated on public roads, it is not maintained regularly,
thereby reducing transportation costs.
68
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Total loading and unloading time for the truck is 30 minutes. A
truck driver is borrowed from the sanitation department on an average
of one day per month for this operation. He applies approximately
12 loads of sludge (approximately 18,000 gallons) to the landspreading
site. This is the total amount of sludge generated on a monthly basis.
Sludge is stored in the digester between applications.
Landspreading System
Liquid Sludge - The sludge tank truck is equipped with a perforated
"T" pipe at the rear of the tank to distribute the liquid sludge by
gravity. In the field, the technique used to empty the load is to drive
in low gear (10-15 mph) starting in the middle of the field making a
continuous circle and proceeding until empty. The driver continues with
this technique until the entire field is covered. A local farmer
harvests hay from the 15 acre City property and discs the sludge under
about once every three years. From two cuttings in 1974, the City field
yielded 1,500 bales which is reported to exceed the yield of nonsludged
fields in the area. No water, soil or plant monitoring system is
provided at this site.
Drying Beds
Because of the proximity of the liquid disposal sites, the drying
beds are only used when the digester needs repair. When the drying beds
are used, the dried sludge is hauled away by local citizens.
Costs
Based on actual operating information provided by the City of Front
Royal, the City is currently disposing of its liquid sludge at a cost of
$5 per dry ton. A more detailed cost analysis follows.
69
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$3.73
4.32
5.78
5
0.5
0.5
$ 390
40
60
COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation 1 0
1947, International Truck, Cost: $ 300
Total Annual Capital Cost
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Driver
Foreman
Superintendent
$ 490
Fringe Benefits at 25 percent
Vehicle Operation and Maintenance
Gasoline $ 50
Oil 10
Antifreeze 10
70
Utilities
Electricity 10
TOTAL ANNUAL OPERATING COST $ 690
TOTAL ANNUAL OPERATING AND CAPITAL COST $ 690
10 PERCENT CONTINGENCY FACTOR $ 70
TOTAL ANNUAL COST $ 760
Total Annual Cost = $760 = $5 per dry ton
Total Sludge Hauled Annually 140 dry tons
1 Vehicles were depreciated over 8 years at 8% interest which
amounts to a depreciation charge of $14.14 per $1,000 per month.
2 A 10% contingency factor is added to cover such items as
administrative overhead.
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GRAND RAPIDS, MICHIGAN
Grand Rapids is a fairly large metropolitan area with a wastewater
treatment plant serving a population of 250,000. The plant currently
vacuum filters approximately 65 percent of its sludge, most of which is
incinerated. The remaining 35 percent is air dried and disposed of on
nearby farmland. Both raw and waste activated sludge are processed at the
facility.
Persons Contacted:
Mr. Qtto Green
Superintendent of Wastewater
Treatment
City of Grand Rapids
Wastewater Treatment Plant
1300 Market Avenue, S. W.
Grand Rapids, Michigan 49502
Telephone: (616) 456-3206
Site Description
Mr. Jim Biener
Director of the Department of
Environmental Protection
City of Grand Rapids
Wastewater Treatment Plant
1300 Market Avenue, S. W.
Grand Rapids, Michigan 49502
Telephone: (616) 456-3206
All sludge from the vacuum filters or air drying beds that is not
incinerated is hauled to one location and used either as a top dressing
on completed portions of a sanitary landfill or spread on nearby farmland.
The farm to which sludge is hauled is located about 10 miles from the
treatment plant. The principal crop grown on the sludge amended soil is
corn.
General Information
The wastewater treatment plant was built in 1929, and upgraded in
1954 to include two primary and four secondary digesters. Vacuum filters
and an incinerator were added in 1959. The design capacity of the plant is
44 MGD with a current average daily flow of 47 MGD. Construction is
presently underway to increase the overall capacity of the plant to 90
MGD. Plans call for the inclusion of the Zimpro heat treatment process and a
general upgrading of the present incinerator.
It is estimated that 55 percent of the plant flow is from industrial
or commercial establishments. There are 190 industries that contribute
approximately 50,000 gal/day of a possibly toxic discharge. Grand Rapids
also has one of the highest concentrations of metal plating industries in
the U.S., although all of these plants are required to pretreat.
The plant is presently producing sludge at the rate of approximately
22 dry tons per day (i.e., 0.18 Ibs/cap/day).
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Sewage Sludge Composition
Table 1 presents data on the metals content of the sludge from the
drying beds and the vacuum filters. The solids content of the sludge
from the air drying beds is -about 25 percent and that from the vacuum
filters is 22 percent.
Transport System
The drying beds are only operated 12-15 weeks during the summer and
handle about 30 percent of the sludge generated in the plant. The
operation consists of one man who fills the beds for an estimated 480
hrs/year at $5 per hour and one man who cleans the beds at an estimated
500 hrs/year at $5.58 per hour. The front end loader used in cleaning the
beds is rented at a rate of $6.22/hr. This includes the cost of fuel and
maintenance for the 500 hrs/year it is in use. The sludge is loaded into
one of several 20 yd3 containers owned and maintained by a contractor who
hauls the sludge away at a cost of $54.40 per load. Out of this, the
contractor pays the farmer $12/load to dump the sludge in a pile on the
farmer's land.
Most of the vacuum filtered sludge is incinerated. However, during
times when the incinerator is not in operation, some digested vacuum
filtered sludge is loaded by conveyor into one of the contractor's
20 yd3 containers for transfer to the farmer's land. In FY 1975, 6
percent of the vacuum filtered sludge, or approximately 320 dry tons were
handled in this manner.
Landspreading System
Since the farmer also operates a large sanitary landfill, he has
considerable heavy equipment at his disposal for applying and incorporating
the sludge into the soil. After the sludge has been stockpiled for several
months, he utilizes a large scraper to spread the sludge at a depth of
about two feet. This is then plowed into the soil with the aid of a
crawler tractor. The farmer feels that this heavy earth-moving equipment
is the only way to efficiently apply dried sludge to the land. During the
1974-1975 year, the farmer applied all of the sludge which he received
onto a 23 acre plot of land. This amounted to over 143 dry tons per acre.
To date, only one application has been made to any one field. However,
at this heavy application rate the farmer has noticed some spots where
nothing will grow within the first year after he has applied the sludge.
These areas amounted to about 5 percent of the total field. Although
the farmer did not have accurate records on crop yield, he stated that
yields did increase significantly on the sludge amended soil the second
year after it was applied.
72
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Cost
Based on actual operating information provided by the City of Grand
Rapids, the City is presently disposing of sludge from its drying beds
at $15 per dry ton and from its vacuum filters at $54 per dry ton. On
the vacuum filter operation, half of the cost of the building was
applied to the filter operation and depreciated at 8 percent over 20 years.
The vacuum filters were depreciated at 8 percent over 10 years. Because
only 6.5 percent of the vacuum filtered sludge is landspread (the remainder
is incinerated), only this portion of all vacuum filtering costs are
included in this analysis. With the drying bed operation, dewatering
accounted for $7 per dry ton while for the vacuum filter operation
dewatering accounted for $48 per dry ton. A more detailed cost break-
down of capital and operating costs for each system follows. No reliable
cost information was obtained regarding the sludge incineration operation.
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COST FOR DISPOSAL OP AIR DRIED SLUDGE
Annual Capital Cost
Vehicle Depreciation 0
Equipment Depreciation 0
Total Annual Capital Cost 0
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Laborer $5.00 23 $2,390
Front End Loader $5.58 24 $2,790
Administration
Trucking $3,200
Sludge Conditioning $ 360
Sludge Storage & Pumping $4,200
$12,940
Fringe Benefits at 40 percent $ 5,"180
Vehicle Maintenance and Operation
Loader Rental $ 3,110
Contract Hauling $15,380
Pumping and Storage $ 4,200
TOTAL ANNUAL OPERATING COST $40,810
TOTAL ANNUAL CAPITAL AND OPERATING COST $40,810
10% CONTINGENCY FACTOR 1 $ 4,080
TOTAL ANNUAL COST $44,890
Total Annual Cost = $44,890 = $15 per dry ton
Total Sludge Hauled Annually 2930 dry tons
1 A 10% contingency factor is added to cover such items as
administrative overhead.
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COST FOR DISPOSAL OF VACUUM FILTERED SLUDGE
Annual Capital Cost
Vehicle Depreciation 0
Equipment Depreciation
1960 Vacuum filter, cost -$81,600 770
Building Depreciation ^
1960 Building, cost - $262,600 $ 1,710
Total Annual Capital Cost $ 2,480
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Operators $ 6.01 19 $ 2,370
Supervision 360
$ 2,730
Fringe Benefits at 40 percent $ 1,090
Vehicle Maintenance and Operation
Contract Hauling $ 1,710
Vacuum Filter Maintenance and Operation
Chemicals $ 3,280
Repairs $ 3,820
Utilities
Electricity $ 5 60
TOTAL ANNUAL OPERATING COST $13,190
TOTAL ANNUAL CAPITAL AND OPERATING COST $15,670
1 Stationary equipment was depreciated over 10 years at 8%
interest which amounts to a depreciation charge of $12.13 per $1,000 per
month.
2 Buildings were depreciated over 20 years at 8% interest which
amounts to a depreciation charge of $8.36 per $1,000 per month.
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10% CONTINGENCY FACTOR 3 $ 1,570
TOTAL ANNUAL COST $17,340
Total Annual Cost = $17,340 = $54 per dry ton
Total Sludge Hauled Annually 320 dry tons
3 A 10% contingency factor is added to cover such items as
administrative overhead.
76
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Table I
METAL ANALYSIS - SLUDGE*
Drying Beds
Filter cake
1975
Jan . Chrome
"
Feb.
Jan. Copper
Feb.
Jan. Nickel
Feb.
Jan. Zinc
Feb.
Jan. Iron
•
Feb.
6300 ppm
4100 "
5000
4700
5100
8500 ppm
5800 "
8000
6300
7400
3600 ppm
2300 "
2300
2400
2900
10100 ppm
7600 "
9000
8800
9000
21000 ppm
16000 "
17000
25000
19000
3200 ppm
1600 "
2300
2700
-2600
3800 ppm
2200 "
3500
2900
3200
3600 ppm
800 "
1300
1500
1700
5700 ppm
3400 "
4700
5600
4800
36000 ppm
24000 "
30000
28000
22000
* All analyses are reported on a dry weight basis.
77
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GREELEY, COLORADO
The City of Greeley, Colorado is a small community of approximately
55,000 population, located approximately 50 miles northeast of Denver.
The City's sewage treatment operation consists of two separate wastewater
treatment systems separated by the Cache La Poudre River. The North
plant, which treats approximately two-thirds of the influent, is an
activated sludge plant. The south plant uses trickling filters. The
sludge produced by both plants is mixed just prior to digestion.
Depending upon weather conditions and land availability, it is either
liquid hauled to farm land or air dried. The effluent from both plants
receives chlorination before release to the river.
Persons Contacted
Mr. Wyatt Sellers Mr. Gary Harkey
Plant Superintendent Water and Sewer Department
Greeley Wastewater Treatment Plant City of Greeley
Greeley, Colorado Greeley, Colorado
Site Description
Liquid Sludge Disposal - The City hauls liquid sludge to farm sites
located approximately 4 to 7 miles from the treatment plant. Selection
of the sites was on a first come, first served basis. At the time of
the visit (October 1975), the City was hauling sludge to six sites and
had a backlog of additional farmers requesting sludge. City policy
limited sludge application at any given site to 10 dry tons/acre.
Air Dried Sludge - The City's air dried sludge is stored in an area
adjacent to the sand drying beds that is accessible to the public. No
regulations or other controls are placed upon the use or amount of
sludge an individual may take.
General Information
The industrial contribution to the treatment plant is equal to
approximately 2 percent of the total flow. Beatrice Foods (dairy) and
the Greeley Meat Company are the two major dischargers to the City's
treatment plant. The population equivalent, based on a BOD of 0.17 Ibs.
BOD/cap/day, is calculated to be approximately 58,000. The overall
treatment plant design capacity is rated at 8 MGD. Currently, the
average flow is 6.5 MGD.
The combined quantity of primary and secondary activated sludge
generated totals approximately 39,000 gallons/day @ 2% solids (i.e., 3.3
dry tons/day). The concentration of solids in the sludge is somewhat
lower than expected due to antiquated equipment and operational problems.
78
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Transport System
Liquid Sludge - In 1974, the City liquid hauled approximately 60
percent of its sludge. The decision to air dry or liquid haul is
dependent on the weather, the crop growing season and site availability.
In general, the City is able to haul liquid sludge 6 to 8 months of the
year. During the remaining months, the sludge is stored in the digesters
or dried on sand beds.
The transport vehicle is an 8 year old 5,500 gallon tractor trailer
which the City purchased for $9,200 in 1974. The tank is filled by
gravity flow from the digesters. Since it takes approximately 40
minutes to load the vehicle (150 gpm), 20 minutes to drive the 10 miles
round trip, and 20 minutes to offload, the vehicle is limited to an
average of six or seven trips a day. The City has recently installed a
pump on the gravity line, which cuts filling time to 15 minutes.
Air Dried - Since most of the air dried sludge is removed by
citizens, the City rarely has to haul away any sludge. In 1974, the
beds were filled 5 times for a total of 500 dry tons. During 1975 the
decision was made to haul liquid sludge to the agricultural lands as
much as possible. Therefore, the sand drying beds were utilized only
once during this period.
Landspreading System
Liquid Sludge - The liquid sludge is applied by gravity flow
directly from the rear of the truck through a spreading T. The farm to
which sludge was being applied at the time of the site visit had received
approximately 152 loads of sludge averaging 3% solids (105 dry tons).
Sludge was placed upon approximately 45 acres of the farm at a rate of
2.3 dry tons/acre. Additional sludge will be hauled to the site weather
permitting. As a general rule, an average of 2 dry tons are applied per
acre. However, up to 10 dry tons have been applied per acre. (Precise
records of the quantity, moisture content and application rates were
only recently started).
Cost
The City currently employs 11 full-time employees and 7 seasonal
employees at the treatment plant. The total operating budget for 1975
amounted to $242,662. Salaries and wages accounted for over 58 percent
of the annual operating cost.
Based on the information provided by the City of Greeley, it
appears that the City is currently disposing of its liquid sludge at a
cost of $22 per dry ton while the cost for dewatering sludge on sand
drying beds is $8 per dry ton. A more detailed breakdown follows.
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Annual Operating Cost
Personnel
Driver
Supervisor
Hourly Rate
$3.73
$6.90
% Time Worked Cost
90 $6,980
10 1,440
Total Personnel Cost $8,420
Fringe Benefits at 17 percent $1,430
Vehicle Maintenance and Operation
Fuel $ 560
Tractor-Trailer Rental $3,600
TOTAL ANNUAL OPERATING COST $ljl,010
TOTAL ANNUAL CAPITAL AND OPERATING COST $14,010
10% CONTINGENCY FACTOR1 $ 1,400
TOTAL ANNUAL COST $15,410
Total Annual Cost = $15,410 = $22 per dry ton
Total Sludge Hauled Annually 700 dry tons
1 A 10% contingency factor was included to cover such items as
administrative overhead.
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COST FOR DISPOSAL OF AIR DRIED SLUDGE
Annual Capital Cost $ °
Annual Operating Cost
Personnel
Operator
Laborer
Supervisor
Hourly Rate
$4.23
3.04
7.16
% Time Worked
15
12
1
Cost
$1,350
730
140
Total Personnel1 Cost $2,220
Fringe Benefits at 17 percent $ 380
Vehicle Maintenance and Operation
(Front end loader with blade)
Fuel $ 360
Rental $ 560
TOTAL ANNUAL OPERATING COST $3,520
TOTAL ANNUAL CAPITAL AND OPERATING COST $3,520
10% CONTINGENCY FACTOR1 $ 350
TOTAL ANNUAL COST $3,870
Total Annual Cost = $3,870 = $8 per dry ton
Total Sludge Hauled Annually 500 dry tons
1 A 10% contingency factor is added to cover such items as
administrative overhead.
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BEAVERCREEK TOWNSHIP. GREENE COUNTY, OHIO
Beavercreek Township, Ohio is a predominately rural area between
Xenia and Dayton, Ohio. The wastewater treatment facility, which is
operated by Greene County, provides tertiary treatment consisting of an
activated sludge process, secondary clarification, and microstrainers.
Sodium aluminate is added to remove phosphorus and improve settling
characteristics. The plant effluent receives post-chlorination before
being discharged into Beaver Creek, 'which drains into the Little Miami
River. All sludge receives secondary aerobic digestion before being
applied to farmland.
Person Contacted
Mr. Charles Lenhart
Superintendent of Wastewater Treatment
Greene Co. Department of Sanitary Engineering
651 Dayton-Xenia Road
Xenia, Ohio 43585
Telephone: (513) 426-4540
Site Description
At the time of the site visit, the County was hauling liquid sludge
to about 14 different site locations. These sites ranged in size from
13 to over 700 acres. The largest site was a sod farm, while corn,
alfalfa, and beans were the major crops grown on the other farms. The
County hauled sludge and applied it to the fields at no charge to the
farmers. However, they preferred not to haul over five miles. Shortly
after the beginning of 1976, the County modified its operation and now
principally hauls sludge to the sod farm which is located four miles
from the treatment plant.
General Information
The County estimates the industrial input into the Beavercreek
Plant to be about 1 or 2 percent of the total flow. The major indus-
trial sources are a meat processing plant which has pretreatment, custom
laboratories, and an aircraft fuel systems manufacturing plant. The
treatment plant serves a population of 23,000 and a population equivalent
of 20,306 based on suspended solids, and a population equivalent of
25,103 based on BOD load. The plant was built in 1965 and expanded in
1972.. The design capacity is 2.5 MGD with a design BOD population
equivalent of 25,000. The average daily flow is 2.618 MGD. The treat-
ment plant with all equipment on line will normally operate at 98 percent
efficiency in the reduction of BOD and 95 percent reduction for suspended
solids.
All sludge leaving the plant receives secondary aerobic digestion.
This amounts to an average of 345,500 gallons per month at 2.2 percent
82
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solids, or about 380 dry tons per year. This represents a solids
loading of 0.09 Ibs/cap/day. While this figure tends to be high, it can
be explained by the type of treatment process in use at the plant.
When the plant was expanded in 1972, two vertical basket centrifuges
were installed but never operated. Plans are to place them into operation
to thicken waste activated sludge from 1 percent to 5 percent before it
goes to the digesters.
Sewage Sludge Composition
Table 1 shows data which was provided by the County on the composition
of the sludge.
Transport System
The County owns a 6,000 gallon tank trailer with a diesel tractor
for hauling sludge. When sludge is hauled, an average of 5 to 6 loads
are hauled per day. The trailer is equipped with a 6-inch valve and
splash plate. Before the County started hauling exclusively to the sod
farm, sludge was applied by driving across the field or from the side of
a road with the aid of hoses. In driving across open fields, the splash
plate was used to unload the truck by gravity flow. This would provide a
12 to 14 foot wide coverage. When fields were too wet or crops were on the
fields, the truck would be parked on a roadside adjacent to the field
and varying lengths of six-inch collapsable hose were unloaded from the
truck and carried out into the field. The sludge would then be allowed
to run down crop rows or to spread out on hay land which often resulted
in heavy but uneven applications. The average time for a 10-mile round
trip haul is 25 minutes to unload with the splash plate or 35 minutes to
unload with the hose. The trailer was purchased in 1972 and the tractor
in 1975 for a total cost of $36,461.
In addition to the trailer tank truck, the county also owns a 1966
1,500 gallon tanker which is loaned to farmers if they wish to haul
their own sludge. Less than 5 percent of the sludge is hauled by this
truck.
Landspreading System
The liquid sludge is applied by gravity flow directly from the rear
of the truck or by hose. A common application rate is two 6,000
gallons/acre or one dry ton per acre. Depending upon the crop grown,
one or more applications will be made to a field each year with a
maximum of about nine. One farmer who was interviewed claims a 330
percent increase in hay yield for land receiving heavy sludge applications
as compared to that which did not receive any sludge. On alfalfa fields,
sludge will be applied immediately after each cutting and possibly after
the alfalfa has started to grow back. On row cropped land, sludge is
applied both while the field is dormant, as well as when crops are on
the field, by running sludge down the rows by gravity flow.
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After the County decided to haul all the sludge to the sod farm,
the fanner purchased 4-inch irrigation pipe, a farm tractor p.t.o.
driven sludge pump, and a big gun nozzle. With this system, the 6,000
gallon tanker is unloaded f^rom the road in 15 minutes. With a 1.4 inch
nozzle and 85 psi. , each load will apply 0.2 inches of sludge to 1.13
acres, i.e., a radius of 125 feet. Cost of spray irrigation equipment
was $7,000.
Cost
Based on information provided by the County, the cost for sludge
disposal from the Beavercreek Township Plant is $40 per dry ton. This
cost may be slightly higher than for other plants because of the small-
scale operation, low percentage of solids in the sludge and the high
depreciation costs on the new transport vehicle. A detailed cost
bre akdown fo1lows.
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation1 $ 6,190
1975, International Tank/Trailer,
Cost: $36,500
Stationary Equipment Depreciation2 140
(Heater and Standing Pipe)
Total Annual Capital Cost $ 6,330
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Driver $5.00 38 $3,960
Superintendent $8.00 6 990
$4,950
Fringe Benefits at 20 percent $ 990
Vehicle Operation and Maintenance
Operation Costs $1,290
Maintenance and Repair Costs $ 160
$1,450
TOTAL ANNUAL OPERATING COST $ 7,390
TOTAL ANNUAL CAPITAL AND OPERATING COST $13,720
10 PERCENT CONTINGENCY FACTOR3 $ 1,370
TOTAL ANNUAL COST $15,090
Total Annual Cost = $15,090 = $40 per dry ton
Total Sludge Hauled Annually 380 dry tons
1 Vehicles were depreciated over 8 years at 8% interest which
amounts to a depreciation charge of $14.14 per $1000 per month.
2 Equipment was depreciated over 10 years at 8% interest which
amounts to a depreciation charge of $12.13 per $1,000 per month.
3 A 10% contingency factor is added to cover such items as
administrative overhead.
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Table 1
Analytical Data Generated by the Beavercreek
Wastewater Treatment Plant Lab on Composite Samples
of Secondary Digested Sludge — Sample Period
August 1 - August 19, 1975
Total Solids - Dry 2.2%
Volatile 54%
Suspended Solids 17,290 mg/1
Volatile 9,520 mg/1
PH -6.9
BOD 2 , 160
Nitrogen 3.25%
Phosphorus 7.32%
as
Potassium 1.58%
as K20
Cd 9 mg/1
Cr 39 mg/1
Cu 568 mg/1
Pb 134 mg/1
Hg 0 mg/1
Ni 28 mg/1
Zn 1,734 mg/1
86
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LaCROSSE, WISCONSIN
The City of LaCrosse, Wisconsin, has a population of approximately
65,000 and is located 120 miles northwest of Madison. The City's
wastewater treatment plant consists of a secondary activated sludge
system which incorporates post-chlorination of the effluent and anaerobic
digestion of the settleable solids. Following digestion, the solids are
vacuum filtered and/or applied directly to nearby farmland. The effluent
is discharged directly into the Mississippi River.
Person Contacted
Mr. Grant Haugstad
Superintendent of LaCrosse
Wastewater Treatment Plant
LaCrosse, Wisconsin
Telephone: (608) 784-4882
Site Description
Presently, the City hauls liquid and vacuum-filtered sludge to
several small farms that vary in size and cropping practice. Any citizen
with land within a radius of 10 miles and east of the Mississippi River
who desires to receive sludge may place a request with the Superintendent
of the LaCrosse Wastewater Treatment Plant. If conditions are favorable
(e.g., groundwater table, soil types, runoff, weather, site accessability,
etc.), the wastewater treatment plant will apply sludge to the property
one or more times during the year.
General Information
Industrial contribution to the wastewater treatment facility is
approximately 50 percent of the total flow. Based on a BOD of 0.17 Ibs.
per cap per day, the population equivalent is approximately 140,000.
The design capacity of the system is 22 MGD with an average daily flow
of 13.9 MGD.
The combined quantity of primary, secondary-clarified and activated
sludge is approximately 190,000 gallons per day at 2.5 percent solids
prior to digestion. Following digestion this equals 0.54 Ibs. of
solids per capita per day (i.e., 4360 dry tons per year) which is a
high generation rate. This high solids loading can be partially explained
by the local brewery which discharges a high solids effluent.
LaCrosse started disposing of its liquid sludge on agricultural
land in 1973. The quantity of sludge increased significantly with the
addition of an activated sludge system. In 1974, a dewatering system
consisting of two vacuum filters was incorporated into the treatment
plant. Following the installation of the filters, the City purchased
their first dry sludge spreader and began applying digested sludge in
cake form to nearby agricultural land.
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Full-scale operation of present land utilization practices began in
April, 1975, with the acquisition of a second cake spreader and a
second liquid tank truck. The City has ordered a third cake spreader
(12-yard capacity) to be in service by March 1976.
Sewage Sludge Composition
Table 1 presents data relative to the metal content of LaCrosse
sludge. Analyzed at the University of Wisconsin for several elements,
the sludge was shown to be fairly low in metals, except Fe (21,000 ppm) .
This particular element has a higher concentration mainly because the
following industries discharge their wastes without any form of pre-
treatment: a manufacturer of heating and air conditioning parts, a
lamination plant, a machine shop, a brewery, and several bottling firms
and laundromats.
Transport System
Liquid Sludge - The City liquid hauls about 15 percent of its
sludge. The decision to liquid haul or to vacuum filter the sludge is
solely determined by the storage capacity of the digesters and the type
of sludge desired by the farmer. In general, the City liquid hauls an
average of 10 to 15 loads of sludge per day at 3 percent solids 40 to 45
weeks of the year. The vehicle used in transporting liquid sludge is a
3,500 gallon tank truck purchased in 1975 at a cos't of $14,000. Two
drivers are used full time to provide a two shift operation during
periods when sludge is liquid hauled (i.e., early Spring and late Fall).
The average haul distance is approximately eight miles one way, with an
average round-trip driying time of 40 minutes. The time required to
load as well as unload the truck is approximately seven minutes.
Vacuum Filtered Sludge- The transport system used in hauling the
filtered sludge includes a 1974 seven yard Ford Knight Spreader, purchased
at a cost of $10,900, and a 1975, 12-yard International Knight Spreader,
purchased at a costof $19,000. Hauling time for the dry sludge is the
same as the wet, with a 30 minute loading time for the seven yard truck
and a 45 minute loading time for the 12 yard truck. An unloading time
of 10 minutes is required for both trucks.
The vacuum filters were purchased in 1972 and 1974 at a cost of
$120,000. They are operated 16 hours a day, 5 days a week with a total
of 8 operators for the two shift operation. The solids content after
dewatering is 25 percent.
Landspreading System
Liquid Sludge - The liquid sludge is applied by gravity flow from
the distribution "T" located at the rear of the vehicle. Each load
covers an area of 15,000 square feet (i.e., 1500 feet long by 10 feet
wide). It is calculated that approximately 1.3 dry tons are applied per
acre per application. No recent problems with odors or flies were
noted, even though the sludge is not always turned under immediately
88
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after being applied. The farmer usually turns the sludge into the soil
after the field has been fully covered.
The City has been and is currently hauling most of its sludge to
soybean, oats, rye, and corn fields. Applications are only made after
the field is cropped or before the spring planting. With the high cost
of inorganic fertilizers, this has made the use of organic fertilizers
(i.e., sludge) even more popular with local farmers in the community.
Vacuum Filtered Sludge - The dried filter cake is applied by a
Knight Spreader dump truck. This vehicle is equipped with a chain
conveyer which moves the dry cake to the rear of the truck where a
grinding mechanism breaks the cake into fine particles and evenly
distributes the material.
Cost
The City currently has 30 employees at the wastewater treatment
plant. Half of the personnel are involved in some aspect of disposal of
digested sewage sludge.
Based on actual operating information provided by the City of
LaCrosse, the 1974 cost for liquid sludge disposal was $49 per dry ton
while for vacuum—filtered sludge, the cost amounted to $81 per dry ton.
For the vacuum-filtered sludge, the cost of dewatering accounts for $68
per dry ton. The major cost items in the dewatering process are personnel
costs of approximately $110,000 and chemical costs of approximately
$70,000. A more detailed cost analysis of each system is presented on
the following pages.
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation ^ $ 2,380
1975-Ford Tank Truck, cost-$14,000
Equipment Depreciation 2 10
Standing Pipe, cost-$50
Total Annual Capital Cost $ 2,390
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
2 Truck Drivers $4.60 100 $19,140
Chemist 4.95 3 310
Chemist Assistant 4.25 3 260
Superintendent 6.90 3 430
$20,140
Fringe Benefits at 38 percent $ 7,650
Vehicle Operation and Maintenance
Parts $ 600
Fuel and Oil 940
Insurance, Fees and Tags 90
TOTAL ANNUAL OPERATING COST $29,420
TOTAL ANNUAL CAPITAL AND OPERATING COST $31,810
10% CONTINGENCY FACTOR 3 $ 3,180
TOTAL ANNUAL COST $34,990
Total Annual Cost = $34,990 = $49 per dry ton
Total Sludge Hauled Annually 710 dry tons
1 Vehicles were depreciated over 8 years at 8% interest which amounts
to a depreciation charge of $14.14 per $1000 per month.
2 Stationary equipment was depreciated over 10 years at 8% interest
which amounts to a depreciation charge of 12.13 per $1000 per month.
3 A 10% contingency factor is added to cover such items as
administrative overhead.
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COST FOR DISPOSAL OF VACUUM FILTERED SLUDGE
Annual Capital Cost
Vehicle Depreciation ^ $ 5,090
1974 Ford Knight Spreader, cost-$10,900
1975 Int. Knight Spreader, cost-$19,000
Equipment Depreciation $17,470
2 vacuum filters, cost-$120,000
Total Annual Capital Cost $ 22,560
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
8 vacuum filter
operators $4.60 100 $76,540
2 Truck drivers 4.60 100 19,140
Chemist 4.95 17 1,730
Chemist Assistant 4.25 17 1,480
Superintendent 6.90 17 2,410
$101,300
Fringe Benefits at 38 .percent $ 38,500
Vehicle Operation and Maintenance
Parts $ 3,400
Fuel and Oil 4,950
Insurance, Fees and Tags 200
Vacuum Filter Maintenance
Chemicals $ 70,000
Parts and repairs 15,000
Utilities $ 11,920
TOTAL ANNUAL OPERATING COST $245,270
TOTAL ANNUAL CAPITAL AND OPERATING COST $267,830
1 Vehicles were depreciated over 8 years at 8% interest which
amounts to a depreciation charge of $14.14 per $1000 per month.
2 Stationary equipment was depreciated over 10 years at 8% interest
which amounts to a depreciation charge of $12.13 per $1000 per month.
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10% CONTINGENCY FACTOR 3 $ 26,780
TOTAL ANNUAL COST $294,610
Total Annual Cost = $294,610 = $81/dry ton
Total Sludge Hauled Annually 3650 dry tons
3 A 10% contingency factor is added to cover such items as
administrative overhead.
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Table 1
LaCrosse Sludge Analysis*
January, 1974
N 2.06%
P 2.79%
K 3.53%
Ca 20.6 %
Mg 0.60%
Na 0.70%
Al 264 ppm
Fe 21,100 ppm
B 159 ppm
Cu 343 ppm
Zn 580 ppm
Mn 309 ppm
Cr 314 ppm
Ba 342 ppm
Sr 121 ppm
Dry Matter 26 %
* Chemical laboratory results are all on a Dry Matter basis,
93
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LAWRENCEVILLE, ILLINOIS
The community of Lawrenceville, Illinois, is located 70 miles due
north of Terra Haute, Indiana and has a population of 5,800. The
community's wastewater treatment plant is a primary treatment-clarifi-
cation system whose effluent is discharged into the Wabash River. The
settleable solids are pumped into a sludge holding tank for storage. At
the end of each week, the sludge is pumped to a vacuum filter for
dewatering prior to being hauled to agricultural land.
Persons Contacted
Mr. Bill Goff
Superintendent of the Wastewater
Treatment Plant
Lawrenceville, Illinois 62439
w
Mr. Francis Perkins
Mayor of Lawrenceville
Lawrenceville, Illinois 62439
Telephone: (618) 943-4115
Site Description
Lawrenceville transports its vacuum-filtered sludge to a 100-acre
farm that is located approximately 8 miles west of the wastewater treatment
plant. The soil on the site is a clay-loam. The farmer plans to plant
the sludge treated land in soybeans and corn in 1976. In the past
farmers have observed improved crop response on sludge treated soils.
However, no yield measurements were available.
General Information
The wastewater treatment facility was constructed in 1961 with a design
capacity of 2.0 MGD. The average daily flow through the treatment plant
is only 0.5 MGD due mainly to the fact that the various industries
within the area presently treat their own wastes. The reasons for the
unusual handling of industrial wastes are the stringent regulatory
controls within the state of Illinois concerning industrial discharges
and the fact that Texaco, whose refinery contributes 95 percent of the
total industrial activity in Lawrenceville, is trying to generate a
favorable working relationship with the town by treating its own wastes.
Settleable solids from the clarifier are pumped into a sludge
holding tank without any stabilization. Based on records from the
wastewater treatment plant, the total amount of sludge filtered in 1975
was approximately 70 dry tons, which amount to 0.06 Ibs of solids per
capita per day. This figure is about half of what it should be for the
type of treatment employed and can only be explained by the fact that
there is no industrial contribution.
94
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The undigested sludge that comes off the vacuum filter at 18
percent solids is hauled to the utilization site.
Sewage Sludge Composition
No sludge analysis was available.
Transport System
The community utilizes a Ford 2-ton dump truck to dispose of its
dewatered sludge. This vehicle was purchased new in 1970 at a cost of
$5,200.
The sludge is hauled once every week (usually c.i Friday) by a
laborer who also operates the vacuum filter. The complete process is an
8-hour job, with loading of the truck taking 5 hours. The site where
the sludge is currently disposed of is located 8 miles from the plant.
It requires a total of 30 minutes of driving and an additional 5 minutes
to unload.
Landspreading System
The City stockpiles the sludge on the land and it is the farmer's
responsibility to spread and turn the sludge under as soon as possible
after application in order to prevent problems from odors.
Cost
The City currently employs 4 full-time personnel at its treatment
plant. The operating budget for Fiscal Year 1975 was $44,850.87, of
which salaries accounted for 40 percent.
Based on actual operating information provided by the City of
Lawrenceville, the City is currently disposing of its vacuum filter
sludge at a cost of $190 per ton. Of this, the cost of dewatering
accounts for approximately $120 per dry ton. Dewatering costs are high
due to the low quantity of sludge produced and the high chemical costs.
A more detailed cost breakdown of the capital and operating costs is
presented on the following page.
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COST FOR DISPOSAL OF VACUUM FILTERED SLUDGE
Annual Capital Cost
Vehicle Depreciation $ 880
1970 Ford Dump Truck, cost-$5,200
Stationary Equipment Depreciation 0
Building Depreciation 0
Total Annual Capital Cost $ 880
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Laborer $3.42 20 $1,420
Superintendent 7.70 7.5 1,200
$2,620
Fringe Benefits at 44 percent $ 870
Vehicle Maintenance and Operation
Repairs $ 0
Fuel and Oil 30
Insurance 180
Utilities $2,130
Vacuum Filter Maintenance
Chemicals $5,430
Parts and Repair 0
TOTAL ANNUAL OPERATING COST $11,260
TOTAL ANNUAL CAPITAL AND OPERATING COST $12,140
10% CONTINGENCY FACTOR 2 $ 1,210
TOTAL ANNUAL COST $13,350
Total Annual Cost = $13,350 = $190/dry ton
Total Sludge Hauled Annually 70 Dry Tons
1 Vehicles were depreciated over 8 years at 8 % interest which amounts
to a depreciation charge of $14.14 per $1000 per month.
2 A 10% contingency factor is added to cover such items as
administrative overhead.
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LEBANON, PENNSYLVANIA
The City of Lebanon, Pennsylvania is a community of approximately
28,000 population which is located 70 miles northwest of Philadelphia.
The City's sewage treatment facility consists of a secondary extended
aeration plant incorporating post chlorination of the effluent and
anaerobic digestion of sewage solids, followed by direct application of
liquid sludge to local farmland.
Person Contacted
Mr. Bob Kline
Superintendent, Lebanon Sewage
Treatment Plant
Lebanon, Pennsylvania
Telephone: (717) 272-2841
Site Description
Only, one land application site is used. It is located approximately
five miles southwest of the sewage treatment plant. The soil is Duffield/
Hagerstorm loam-limestone.
General Information
The plant was constructed in 1962 with a design capacity of 6.5
MGD. The average daily flow is 4.0 MGD. The industrial input into the
City's treatment facility is estimated to be 25 percent of the total
flow, with a population equivalent of approximately 45,000. The sludge
is anaerobically digested with a solids content of 4 percent. It is
stored in a secondary digester until an appropriate time is selected to
apply the sludge to nearby farm land.
The total sludge after digestion leaving the plant and applied to
farm land averages 1,055,900 gals/year at 4 percent solids (i.e., 180
dry tons of solids per year). This calculates to 0.035 Ibs/cap/day.
This generation rate appears to be low. One explanation for this may be
that sludge records are kept on the number of loads each week and not
the total gallons. Two different capacity tank trucks are used by the
wastewater treatment plant to transport liquid sewage sludge. This
makes record keeping difficult, as it does not indicate exactly how many
loads each truck hauls. When the plant was built, a coil vacuum filter
was included in the total facility design as the method of dewatering.
The filter was in operation until 1966. At that time the relative
economics of the vacuum filter operation were assessed and it was determined
that landspreading of liquid sludge would be more cost-effective. The
City then began hauling liquid sludge to a local landfill until the
State of Pennsylvania prohibited the disposal of sewage sludge in landfills.
97
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Liquid sludge is now used on agricultural lands. This practice has
resulted in a limited number of complaints concerning odors which were
registered from residents near the application fields. It is assumed
that the complaints have resulted from applying liquid sludge near
' residences without discing the sludge under.
Lebanon is considering upgrading its facilities in the future,
although the method of sludge disposal is expected to remain the same.
Sewage Sludge Composition
No analysis of the sludge was available.
Transport System
Currently, all digested liquid sludge is hauled to a farm approx-
imately five miles from the treatment plant in a 1962 International
2,000 gallon tank truck and a 1963 Diamond "T" 1,600 gallon tank truck.
The liquid sludge flows by gravity from the digester to the liquid tank
trucks. From the plant, the sludge is hauled to a 100 acre farm plot.
The time involved in the total operation is 30 minutes round trip (i.e.,
10 minutes to load, 15 minutes in traveling, and 5 minutes to unload the
truck) . The truck driver averages 600 loads per year with the tfank
trucks; of this, the Diamond "T" hauled approximately 200 loads while
the remaining 400 loads are hauled by the International. The decision
to haul on a particular day is solely based upon the availability of
land, weather conditions, and the season of the year. In general, the
City hauls most of its sludge during early spring and late fall, after
the land has been fully or partially cropped. Corn is the principal
crop to which sludge has been applied.
Landspreading System
The digested liquid sludge is applied to the land by a single pipe
extended from the rear of each tank truck. The driver controls the
application of sludge by opening and closing a valve located on the rear
of the truck. Once the valve is open, the truck proceeds in a straight
line in low gear (i.e., 10 to 15 mph) until the vehicle is empty. There
is a heavier application at the start of the operation and a much
lighter application at the end due to the method of spreading employed.
The driver spends 14 percent of his working year hauling sludge to the
land disposal site. Assuming 180 dry tons of sludge were applied per
year to the 100 acre farm, approximately 1.8 dry tons/acre/year is
disposed of on this land. The sludge is not immediately turned under by
the farmer after application. According to the farmer, he has noticed a
great increase in crop yields where sludge has been applied.
Cost
Utilizing actual operating cost information provided by the City of
Lebanon, it appears the City is currently disposing of its sludge at a
cost of $28 per ton of dry solids. A more detailed cost breakdown follows.
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation 1
1962, International, cost-in 1970-$1,300 $ 220
Stationary Equipment Depreciation 2
Standing Pipe, cost-$500 70
Total Capital Cost $ 290
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Driver $4.00
Maintenance 5.02
Maintenance
Assistant 4.13
Superintendent 6.50
14
1
1
0.5
$1,160
10
10
70
$1,250
Fringe Benefits at 20 percent $ 250
Vehicle Operation and Maintenance
Repairs $2,060
Gasoline 430
Oil 30
Insurance and Fees 300
$2,820
TOTAL ANNUAL OPERATING COST $4,320
TOTAL ANNUAL CAPITAL AND OPERATING COST $4,610
10% CONTINGENCY FACTOR 3 . $ 460
TOTAL ANNUAL COST $5,070
Total Annual Cost = $5,070 = $28 per dry ton
Total Sludge Hauled Annually 180 dry tons
1 Vehicles were depreciated over 8 years at 8% interest which amounts
to a depreciation charge of $14.14 per $1000 per month.
2 Stationary equipment was depreciated over 10 years at 8% interest
which amounts to a depreciation charge of $12.13 per $1000 per month.
3 A 10% contingency factor was included to cover such items as
administrative overhead.
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LITTLETON, COLORADO
The City of Littleton, Colorado is a community of approximately
41,000 population located about 10 miles south of Denver, Colorado. The
sewage treatment facility consists of a trickling filter and a Purox
package plant. Sludges generated are anaerobically digested and dried
on sand drying beds. The dried sludge rs then used on City owned lands
or sold to the general public for $2 per cubic yard.
Persons Contacted
Mr. David Godsey
Superintendent
Sewage Treatment Plant
Littleton, Colorado
Telephone: (303) 794-4214
Site Description
Mr. Charlie Kerven
Assistant Superintendent
Sewage Treatment Plant
Littleton, Colorado
Telephone: (303) 794-4214
The City's sand drying bed sludge is stockpiled for later use on
City parks, flower beds, etc., or is sold to the general'public at
$2 per cubic yard. There are no controls on the usage of the digested
air dried sludge on either the City or general public.
General Information
The treatment plant consists of two parts: a primary trickling filter
plant with a design capacity of 4.5 MGD and a secondary Purox package plant
with a design capacity of 1 MGD. The population equivalent, based on a BOD
of 0.17 Ibs/cap/day is 44,520. The average daily flow is 5 MGD. Because
storm water is separate, daily flow rarely exceeds the current design
capacity.
The City reported flow of primary and secondary sludge at 18,000
and 6,000 gallons per day respectively at approximately 2 percent solids.
Based on these figures a combined sludge production was calculated to be
2 dry tons per day prior to digestion. It is assumed that the digestion
in this case gives a reduction in total solids of approximately 30
percent. Therefore, total sludge production after digestion is estimated
to be 1.4 dry tons per day (510 dry tons/year) or .07 Ib/capita/day.
The City is presently constructing a new plant to be shared with
another community. This should be on line by late 1977.
Sewage Sludge Composition
No sludge analysis was available.
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Transport System
Sludge from the sand drying beds is stockpiled and removed mainly
by private citizens. An unknown quantity is hauled in the City's dump
trucks for use on City property.
Sand Drying Bed Operation
The ten sand drying beds occupy an area of approximately 1.5 acres.
Each bed is emptied about four times a year. The sludge remains on the
drying bed for approximately 8 to 10 weeks during the summer and 10 or
more during the winter. Sludge removed from the drying beds during the
winter months is stockpiled separately so that it,may dry further before
utilization. Cleaning the beds requires 16 man hours per bed, while
loading requires 4 to 5 man hours.
Costs
Based on information provided by the City, the cost for disposal of
the City's air dried sludge is $13 per dry ton. A more detailed cost
analysis is attached.
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COST FOR DISPOSAL OF AIR DRIED SLUDGE
Annual Capital Cost
Vehicle Depreciation 0
1964 Crawler Tractor, Cost: $2,700
Equipment Depreciation" $2,450
Dry Beds
Total Annual Capital Cost $ 2,450
Annual Operating Cost
Personnel Hourly Wage % Time Worked Cost
Operator $4.50 19 $1,850
Operator 4.50 19 1,850
$3,700
Fringe Benefits at 20 percent $ 740
Vehicle Maintenance and Operation
Repairs $ 220
Fuel, oil $ 160
$ 380
Maintenance of Beds $2,200
TOTAL ANNUAL OPERATING COST $ 7,020
TOTAL ANNUAL CAPITAL AND OPERATING COST $ 9,470
10% CONTINGENCY FACTOR3 950
REVENUE (Sale of sludge at $2 per cubic yard) $ 4,000
TOTAL ANNUAL COST $ 6,420
Total Annual Cost = $6,420 = $13 per dry ton
Total Sludge Hauled Annually 510 dry tons
1 Vehicles were depreciated over 8 years at 8% interest which amounts
to a depreciation charge of $14.14 per $1000 per month.
2 Equipment was depreciated over 10 years at 8% interest which amounts
to a depreciation charge of $12.13 per $1000 per month.
3 A 10% contingency factor is added to cover such items as
administrative overhead.
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LOUISVILLE, KENTUCKY
Louisville, Kentucky is located in north central Kentucky. The
City provides primary treatment and serves a population of approximately
500,000. The design capacity is 100-105 MGD and the average daily flow
is 90 MDG. Between 80 and 85 percent of the collection system is combined
storm and sanitary sewers. The maximum storm flow capacity of the plant
is 338 MGD.
Persons Contacted
Thomas McBride
Superintendent
Richard Hutchelson
Plant Manager
Dean Taylor
Consultant and Former Superintendent
Morris Foreman Treatment Plant
4522 Algonquin Parkway
Louisville, Kentucky 40211
Telephone: (502) 775-6481
Site Description
The City currently uses an eleven acre landfill site. Sewage sludge
is the only material disposed of at this landfill.
General Information
At the time of our visit, a $66 million expansion of this Łlant was
under construction and should be fully operational in early 1976. This
expansion will provide secondary (activated sludge) treatment. The
design capacity is 200 MGD. In the new system, the sludge will be
vacuum filtered, oxidized (Zimpro), and incinerated (multiple hearth).
The incinerators are equipped with waste heat boilers which will htit
the solids handling building and the administration b_ilding. The
settleables are currently anaerobically digested and vacuum filtered.
The digested sludge is about 6.8 percent solids. This sludge is
thickened to about 14 percent solids then vacuum filtered to about 29
percent solids. In fiscal year 1975, 15,900 tons of filter cake were
produced representing 4590 tons of dry solids. About 50% of the flow and
BOD load on this plant is from industrial sources.
Sewage Sludge Composition
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The following heavy metals analysis has been performed on the
sludge:
HEAVY METALS ANALYSIS-1974
Concentration
Constituent (ppm dry wt. basis)
Zn 4,486
Cr 2,128
Cd 186
Ni 883
Pb 2,066
Cu 1,272
Fe 18,386
Mn 303
Hg 0.34
Transport System
Sludge is hauled from the plant by three fifteen cubic yard dump
trucks to the landfill site. The site is located approximately three
miles from the plant and the average round trip time per load varies
from 30 to 45 minutes. The dump trucks are loaded from an inclined belt
conveyor running from the vacuum filters.
Landfill Operation
The sludge is dumped into piles at the landfill site. Three to
four times per year a contractor is brought in to spread and cover the
sludge. This operation requires two days on each occasion.
Some developers use the sludge as a substitute for top soil.
Anyone can request the sludge and pick it up at the landfill. However,
the plant personnel prefer that they are informed before large quantities
of the sludge are taken.
Cost
Based on information provided by the City of Louisville, the City's
cost for disposal of vacuum filtered sludge in fiscal year 1975 was
$50 per dry ton. Of this, the cost of dewatering the sludge was about
$33 per dry ton. Major costs for dewatering included personnel costs
of about $49,000, vacuum filter maintenance of $26,000 and chemical
costs of $26,000.
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COST FOR DISPOSING OF VACUUM FILTERED SLUDGE
Personnel (includes fringe benefits) $ 58,190
2 Vacuum Filter Operators
1 Laborer
1 Truck Driver
1 Supervisor
Plant
Depreciation of Vacuum Filters 18,080
Maintenance of Vacuum Filters and Trucks 30,050
Chemicals and Materials 25,940
Utilities 20,000
Transportation (includes capital cost for trucks) 55,990
SUBTOTAL $208,250
10 PERCENT CONTINGENCY FACTOR1 $ 20,820
TOTAL ANNUAL COST $229,070
Total Annual Cost = $229,070 = $50 per dry ton
Total Sludge Hauled Annually 4590 dry tons
1 A 10% contingency factor is added to cover such items as
administrative overhead.
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MACON, GEORGIA
The City of Macon, Georgia is a community of approximately 100,000
population located 70 miles southeast of Atlanta, Georgia. The City's
Lower Poplar Street sewage treatment facility consists of a secondary
trickling filter plant incorporating pre-chlorination of the influent
and anaerobic digestion of primary and secondary clarifier solids. The
digested solids are dewatered on sand drying beds or applied directly to
treatment plant land.
Person Contacted
Robert Moore
Superintendent of the Lower Poplar
Street Sewage Treatment Plant
780 Third Street
P. 0. Box 108
Macon, Georgia 31202
Telephone: (912) 745-9411 ext. 282
Site Description
Liquid Sludge Disposal
City owned property adjacent to the treatment plant has been
utilized for the past eight to ten years for the disposal of liquid
sludge. This particular piece of property is utilized because hauling
costs are minimal' it is always available for sludge disposal, and there
are no residential dwellings adjacent to the property. The soil is of
the Chewacla classification (a sandysilt to siltysand). No fertilizer
other than sludge is used to produce the hay grown on the property.
Drying Bed Sludge Disposal
Sludge from the drying beds is made available for use by area
residents. In 1973, many local farmers used the dried sludge for soil
erosion control. However, in 1974 the drying beds were used to a very
limited extent because the City preferred to liquid haul to their
hayland. This resulted in increased hay revenue. Also the drying beds
are old and very inefficient.
General Information
The sewage treatment plant is a primary clarification system
followed by a trickling filter, secondary clarification and discharge.
The sludge goes through both primary and secondary anaerobic digesters.
The detention time is approximately three months with the solids content
of the sludge estimated to be about four percent.
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The plant superintendent estimates the industrial input into the
Lower Poplar Street Plant to be about 30 percent of the total flow.
Principal industrial contributors are a tannery, a poultry processor, an
oil and soap manufacturing plant, a zipper manufacturer, and a textile
dyeing operation. Treatment plant personnel estimated that the Lower
Poplar Street Plant serves 60 percent of the residential community of
Macon with the remainder flowing into the Rocky Creek Plant (with a 14
MGD capacity). Plans for a plant expansion are forecasted in three
years due to the present overload on the system. The average daily flow
through the plant is 12.8 MGD and the design capacity was 12 MGD. The
effluent is discharged into the Ocmulgee River.
Sewage Sludge Composition
Table 1 presents data on the sludge analysis. Samples were taken
from the #5 secondary digester on October 9, 1975 by SCS Engineers and
analyzed for a comprehensive list of heavy metals. As is indicated, the
sludge is fairly low in heavy metals.
Transport System
Liquid digested sludge is hauled at 4 percent solids content in
a 1600 gallon tank mounted on a one and a half ton dump truck. Since
sludge is only hauled about 40 days out of the year, the tank is
removed during the remainder of the year to free the truck for main-
tenance work around the plant. Although sludge is hauled a relatively
small number of days each year, the operation is spread out over a
nine month period as shown in Table 2. On days that sludge is hauled,
an average of 24 loads per day are removed. The average haul distance
is about one mile with a round trip driving time of 15 minutes. Time
required to load and unload the tank is about five minutes each.
Landspreading System
The liquid sludge is applied to the field by gravity flow from the
rear of the truck. Two pipes, with hydraulic valves that are operated
from inside the cab, discharge sludge onto a metal splash pan. Each
tank load will cover an area of about 10 feet wide by 1000 feet long,
which gives an application rate of about 1 dry ton per acre. During
1974, the application of sewage sludge applied on the City's property
averaged 2 dry tons per acre. Sludge is applied to the hay field when-
ever the ground is sufficiently dry for the truck to operate and the hay
is at a stage of growth which will not be hampered by an application of
sludge. Because the sludge is being applied to an established hay
field, the ground is not cultivated and therefore the sludge is not
turned under. Even so, there were no apparent problems with odors or
flies. At the time of the site visit there had been two cuttings of hay
with a third cutting possible. The local farmer who bales the hay for
the City pays 25C per bale which amounted to $1,650 for the two cuttings
in 1974.
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Costs
Based on actual operating information provided by the City of
Macon, it appears the City is- currently disposing of its digested
sewage sludge at a cost of $8 per ton of dry solids. A more detailed
breakdown of the capital and operating costs follows.
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Stationary Equipment Depreciation1 $ 40
(Standing Pipe)
Total Annual Capital Cost $ 40
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Driver $2.40 14 $ 680
Office Manager 4.77 2 200
Superintendent 6.97 2 290
$1,170
Fringe Benefits at 33 percent $ 390
Vehicle Operation and Maintenance:
Gasoline $ 180
Oil and Lube 10
Insurance 300
Licenses 2
Parts 330
Labor for Repairs 290
$1,110
TOTAL ANNUAL OPERATING COST $2,670
TOTAL ANNUAL CAPITAL AND OPERATING COST $2,710
10 PERCENT CONTINGENCY FACTOR2 $ 270
SUB TOTAL $2,980
REVENUE (Sale of Hay) $1,650
TOTAL ANNUAL COST $1,330
Total Annual Cost = $1,330 = $8 per dry ton
Total Sludge Hauled Annually 170 dry tons
1 Stationary equipment was depreciated over 10 years at 8% interest
which amounts to a depreciation charge of $12.13 per $1,000 per month.
2 A 10% contingency factor is added to cover such items as
administrative overhead.
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TABLE 1
MACON, GEORGIA
SLUDGE ANALYSIS
(Emission Spectrophotometry)
Element PPM DRY Wt.
Si 190,755
Ca 11,304
Al 84,780
Fe 31,793
Mg 7,772
Ti 5,581
P 4,027
Ba 1/059
B 25
Pb 381
Sn 106
Mn 360
Cr 572
Ga 42
Cu 148
Ni 106
Bi 14
V 92
Ag 16
Na 5,157
Zn 1/483
Zr 515
Co 42
K 3,391
Sr 226
Cd 42
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TABLE 2
Volume of Liquid Sludge Hauled from Macon's
Lower Poplar Street Plant*
Month
January
February
March
April
May
June
July
August
September
October
November
December
Totals
1972
189,880
0
141,|639
33,560
12,390
0
15,980
63,858
4,240
0
45,844
19,091
526,482
Year
1973**
0
0
6,963
0
6,890
3,975
0
0
0
0
0
0
19,828
1974
0
0
12,845
4,404
28,442
4,771
19,226
2,110
15,047
35,416
0
15,414
137,675
*Volumes expressed in cubic feet
**During this year the digesters were undergoing major repairs;
therefore, the sewage sludge was piped to drying beds.
Ill
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ROCHELLE, ILLINOIS
The City of Rochelle, Illinois is a small community of
approximately 9,000 population, located 75 miles west of Chicago,
Illinois. The City's treatment facility is divided into two sepa-
rate plants. The domestic wastes go to the activated sludge plant
and the major industries' wastes go to the trickling filter plant.
The activated sludge plant effluent subsequently is pumped to the
later units of the trickling filter plant. All sludges are combined,
thickened, vacuum filtered and applied to farmland.
Person Contacted
Mr. Paul Barry
Superintendent of Water and
Waste Water Facilities
Rochelle Municipal Utilities
120 N. 7th Street
Rochelle, Illinois 61068
Telephone: (815) 562-2011
Site Description
Most of the City's vacuum filtered sludge is hauled to one farmer
who is responsible for spreading the material on his fields and incorporating
it into the soil. A limited amount is stockpiled at the plant for City
residents to take. If a resident can use a full truck load, plant
personnel wiil deliver it to his residence.
General Information
Mr. Paul Barry estimated the industrial input into the City's
treatment facilities to be between 60 and 70 percent of the total flow.
The population served by the plant is 9,000, with a population equivalent
of 165,000. The design capacity is 4 MGD with an average daily flow of
3.2 MGD. The effluent from the trickling filter plant is discharged
into the Kyte River.
The trickling filter plant receives wastes from a large slaughter-
house and also from a yarn dyeing company. The plant consists of
paunch removal (for the packing house wastes only), preliminary units,
primary settling units, three-stage trickling filtration, two-stage
aerated tertiary lagoons, microscreening, and chlorination. The
effluent from the activated sludge plant is directed to the tertiary
lagoons. A portion of the waste sludge from the facilities is anaero-
bically digested. Both the undigested and digested sludges are then
combined, thickened, and vacuum filtered. The plant produces 150 tons
per week of sludge at 25 percent solids.
112
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Sewage Sludge Composition
Table 1 presents data on the composition of the vacuum filter cake
sludge.
Transport System
The City uses five trucks at the wastewater plant to haul the
paunch manure, grit and screenings to the City sanitary landfill and the
vacuum filtered sludge to the farm land. Four of the trucks have 8 yd3
grain dump boxes and the newest has an 8 yd3 heavy duty dump box. The
grain boxes were purchased because of their lower cost. However, because
of their light construction and the corrosive nature of the sludge,
maintenance costs for the boxes are high.
Trucks are filled by backing them under a conveyor belt in the
vacuum filter building. As one is being filled the other is being
emptied. Three trucks are used in this operation while the other two
haul grit and screenings. The haul distance to the farm is 13 miles
round trip requiring 25 to 30 minutes. An average of 6 to 7 loads are
hauled per day in a five day week.
Landspreading System
The farmer has a concrete paved feedlot which is not being utilized.
The City trucks dump the sludge on the paved area for the farmer to
spread. A farn. manure spreader is used to spread the sludge on a daily
basis. If the fields are dry, sludge is dumped directly on the field to
reduce the haul distance for the farmer in spreading the material. The
Illinois Environmental Protection Agency permit on the Rochelle Sludge
Utilization Project, specifies that sludge cannot be stockpiled at a
utilization site for longer than 2 months, that a maximum of 100 dry
tons total accumulation can be applied to a site, and that sludge must
be applied at or less than the acceptable nitrogen agronomic rate.
The farmer who is presently receiving the sludge applies about 25
wet tons per acre (6 dry tons/acre). In addition, based on soil tests,
he applies 200 Ib/acre of 0, 46, 0 commercial fertilizer. Through
experience the farmer has learned that he must allow the sludge to dry
on the field for about a day prior to incorporation in the soil with
an offset disc or chisel. Otherwise, the sludge is too slippery for
tractor operation.
Cost
The total cost to the City of Rochelle for sludge disposal on farm
land is $89 per dry ton. This is a very complete figure which includes
the depreciation, maintenance, and operating costs for the vacuum filter
operation and truck hauling as well as all personnel cost. The
dewatering operation accounts for about $75 per dry ton of this total
cost. The major cost items which make dewatering so high are depreciation-
$60,000, labor—$30,000 and chemicals—$25,000.
113
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COST FOR DISPOSAL OF VACUUM FILTERED SLUDGE
Annual Capital Cost
Vehicle Depreciation $ 3,510
1969 Chev. Grain Truck", cost: $5,248
1969 Chev. Grain Truck, cost: $5,248
1972 Chev. Grain Truck, cost: $5,200
1973 Chev. Grain Truck, cost: $6,000
1974 I. H. Dump Truck, cost: $9,500
Stationary Equipment Depreciation 2 $29,140
Vacuum Filter Building Depreciation 3 $30,130
Total Annual Capital Cost $62,780
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
2 Laborers $4.55 100 $18,930
1 Laborer 4.55 50 4,730
Laboratory 5.00 12.5 1,300
Maintenance 5.25 25 2,730
.Supervisor 10.00 20 4,160
$31,850
Fringe Benefits at 25 percent $ 7,960
Vehicle Operation and Maintenance
Repairs $ 3,150
Fuel and Oil $ 1,000
Vacuum Filter Maintenance
Chemicals
Lime $14,030
Fe Cl $10,030
Acid $ 1,080
1 Vehicles were depreciated over 8 years at 8 percent interest,
which amounts to a depreciation charge of $14.14 per $1,000 per month.
2 Stationary equipment was depreciated over 10 years at 8 percent
interest which amounts to a depreciation charge of $12.13 per $1,000 per
month.
3 Buildings were depreciated over 20 years at 8 percent interest
which amounts to a depreciation charge of $8.36 per $1,000 per month.
114
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Parts and Repairs $ 8,400
Utilities
Electricity @ $0.0239/kwh $18,230
Water 120
TOTAL ANNUAL OPERATING COST $ 95,850
TOTAL ANNUAL CAPITAL AND OPERATING COST $158,630
10 PERCENT CONTINGENCY FACTOR 4 $ 15,860
TOTAL ANNUAL COST $174,490
Total Annual Cost = $174,490 = $89/dry ton
Total Sludge Hauled Annually 1950 dry tons
4 A 10 percent contingency factor is added to cover such items as
administrative overhead.
115
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Table 1
Filter Cake Sludge Analysis
Ammonia Nitrogen (N) .21% *
Organic Nitrogen (N) 2.41% *
Total Nitrogen (N) 2.62% *
Phosphorous (PO,) 4.1% *
Phosphorous (P) 12.7 ppm*
Phosphorous (^2°^ 29.2 ppm*
Cadium .2 ppm*
Zinc 135.2 ppm*
pH 12.1
Total solids 25.2%
*Reported on a dry weight basis
116
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SALEM, OREGON
Salem, Oregon is a community of approximately 100,000 population,
located 50 miles south of Portland, Oregon. The City's wastewater
treatment facility consists of a secondary trickling filter with
anaerobic digestion of the settleable solids, followed by lagoon
drying and/or direct application of liquid sludge to nearby farmland.
Persons Contacted
Mr. Cliff Reed Mr. Lyle Klampe
Superintendent of Wastewater Field Representative - BIOGRO
Plant Operations City Hall
City Hall 555 Liberty Street, S.E.
555 Liberty Street, S.E. Salem, Oregon 97301
Salem, Oregon 97301 Telephone: (503) 393-3806
Telephone: (503) 393-3806
Mr. Don Marske
CH2M-Hill, Engineers
2929 North Mayfair Road
Milwaukee, Wisconsin 53222
Telephone: (414) 774-5530
Site Description
The City hauls liquid sludge to several different site locations.
Any farmer within a reasonable haul distance (i.e., five-mile radius)
who desires to have sludge placed on his land may place a request with
the City and, if conditions are right (e.g., weather, season of the
year, site accessibility, runoff, groundwater table, etc.), the treat-
ment plant will make one or two applications of sludge to his land.
General Information
The Superintendent of Wastewater Operations estimated the indus-
trial input into the treatment facility to be approximately 6 percent of
the total flow. However, during the summer months, the industrial input
increases to approximately 50 percent of the total flow because of the
seasonal industries (canneries) in the area. The population equivalent,
based on a BOD of 0.17 Ib/cap/day, is calculated to be 142,000. The
overall treatment plant design capacity is rated at 14.7 MGD, with an
average daily flow of 28 MGD. The effluent is discharged directly into
the Willamette River. Because of the overload on the system, the City
is currently in the midst of constructing a tertiary plant incorporating
activated sludge, which is scheduled for completion by midsummer of
1976. With the expanded plant the City intends to dispose of sludge by
liquid application, using modifications of its current system. This new
system will incorporate the purchase of three new tank trailers which
will be used to transport the liquid sludge to the field. The sludge
will be pumped from the tankers to two 3-wheeled sludge applicator vehicles.
117
-------
To encourage use of the increased sludge output from the expanded plant,
the digested sludge produced is being promoted under the name of BIOGRO,
an organic fertilizer and soil conditioner.
The combined quality of primary and secondary trickling filter
sludge generated by the present system totals 50,000 gallons per day at
3.5 percent solids (i.e., 7.2 dry tons/day). The total sludge leaving
the plant after digestion averages 6 million gallons per year at 5.5
percent solids (i.e., 1,376 dry tons/year or 0.087 Ibs/cap/day). These
figures compare closely to national averages with the same type of
handling and processing.
Sewage Sludge Composition
No sludge analysis was available.
Transport System
Currently, the City hauls liquid sludge by a single 2,500 gallon
tank truck, purchased in 1969 at a cost of $13,000. The decision to air
dry or liquid haul is solely predicated upon the availability of a
readily accessible field, weather conditions, season of the year, and
the haul distance to the site. Generally, the City liquid hauls its
sludge at 5.5 percent solids every week of the year.
The sewage sludge is stored in three anaerobic digesters (2.6 million
gallons combined capacity) until spreading of the sludge occurs. During
the 1975 year, it; was reported that 2,000 loads were handled by liquid
tank truck. Of the total amount of digested sludge, 80 percent is spread
by liquid tank truck and 20 percent is piped to the lagoon drying beds.
One driver is used full time during the periods when sludge is being
liquid hauled. The average haul distance is approximately 10 miles, one
way, with an average round trip driving time of 25 minutes. It takes
approximately 10 minutes to load and 5 minutes to unload. The transport
vehicle is unloaded by gravity flow with no spreading or distribution
device.
The proposed "new" system will be implemented during the early part
of 1976. This system will incorporate the use of the existing tank
truck, plus three new 6,000 gallon tanktrailers, purchased at a total cost of
$84,000. The four vehicles will be used solely for transporting liquid
sludge to" the disposal sites. Two new 3-wheel tank vehicles will be
stationed at the disposal site, as they are strictly off-road vehicles
and are more adapted to spreading and traversing land otherwise unaccess-
ible to other types of transport vehicles. Upon arrival of the tanker,
a 3-wheeler will be loaded and the liquid sludge applied at an even
distribution rate.
118
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Landspreading System
The liquid sludge is applied by gravity flow directly from the rear
of the truck. The City has experimented with pumps and hoses but found
it easier and more dependable to simply let the sludge drain by gravity.
No problems of odors or flies were noted, even though the sludge is not
always turned under immediately after application.
The City has been and is currently hauling most of its sludge to
onion, grain, and pasture fields with the remaining sludge being stored
in a holding pond at the wastewater facility. With expansion of the
present plant, plans are to increase the efficiency of the landspreading
operation to maintain costs at a minimum level.
f
Costs
Based on actual operating information provided by the City of
Salem, it appears the City is currently disposing of its liquid sludge
at a cost of $40 per ton of dry solids. Sludge handling and disposal
cost will probably increase with full implementation of the new disposal
system being proposed for the spring. This increase will be due basi-
cally to the increased cost of vehicle depreciation, operation and
maintenance. A more detailed cost analysis of the present system is
attached.
119
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation $ 2,210
1969, International, Cost: $13,000
Standing Pipe Depreciation 150
Total Annual Capital Cost $ 2,360
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Driver $ 5.35 80 $ 8,900
Chemist $ 5.80 5 600
Foreman $ 5.80 100 12,060
Superintendent $10.00 5 1,040
Overtime (10 hours every 2 weeks) $ 1,390
$23,990
Fringe Benefits at 23 percent $ 5,520
Vehicle Maintenance and Operation:
Average at $420 per month $ 5,040
Contractual Costs $ 5,000
TOTAL ANNUAL OPERATING COST $39,550
TOTAL ANNUAL CAPITAL AND OPERATING COST $41,910
10 PERCENT CONTINGENCY FACTOR 3 $ 4,190
TOTAL ANNUAL COST $46,100
Total Annual Cost = $46,100 = $40 per dry ton
Total Sludge Hauled Annually 1,146 dry tons
1 Vehicles were depreciated over 8 years at 8% interest which
amounts to a depreciation charge of $14.14 per $1,000 per month.
2 Stationary equipment was depreciated over 10 years at 8% interest
which amounts to a depreciation charge of $12.13 per $1,000 per month.
3 A 10% contingency factor was included to cover such items as
administrative overhead.
120
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SALT LAKE CITY, UTAH
The City of Salt Lake City, Utah is a community of approximately
180,000 population. The City's wastewater treatment facility consists
of a secondary standard rate trickling filter that incorporates pre-
chlorination of the effluents. The settleables are pumped to anaerobic
digesters. The digested sludge is either air dried in drying beds or
centrifuged.
Person Contacted
Mr. Jack Peterson
Superintendent of Wastewater Operation
1850 N. Redwood Road
Salt Lake City, Utah 84116
Telephone: (801) 328-7611
Site Description
Centrifuged Sludge - The City hauls centrifuged sludge to either the
Salt Lake City Airport or uses the sludge as fill material around the
plant.
Air Dried Sludge - The City's air dried sludge is stockpiled for
one year as required as a protective feature by state law prior to being
made available to local citizens.
General Information
The treatment plant is a primary clarification system followed
by a trickling filter, secondary clarification and discharge. The
sludge goes through both primary and secondary anaerobic digesters, with
a detention time of approximately three months at 3.0 to 3.5 percent
solids.
The City Superintendent of Wastewater Treatment Facilities, estimated
the industrial input into the City's treatment facilities to be less than
10 percent of the total flow. The population equivalent based on a BOD
of 0.17 Ibs/cap/day is 250,000. The overall treatment plant design capacity
is rated at 45 MGD with an average daily flow of 41 MGD. The City is
in the planning stages for a plant expansion.
The combined quantity of primary and secondary clarified sludge is
approximately 43,500 Ibs per day on a dry weight basis or 7,910 tons per
year. This represents 0.24 Ibs/cap/day which in comparison to the
national average is above the norm. This can be partly explained by the
type of industrial discharge.
Sewage Sludge Composition
No analysis was available.
121
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Transport System
Centrifuged - The City currently hauls about 80 percent of its
sludge at 21 percent solids when weather conditions permit and when the
airport requests sludge. Dewatered sludge has been hauled to the airport
for the past two years and used at the plant for the past ten years.
Transporting this sludge is accomplished with a 1961 International 10-
wheel - 13 ton dump truck purchased at a cost of $12,000.
It was reported that an average of two loads per day is hauled from
the plant. The haul distance is approximately 5 miles one way with an
average round trip driving time of 20 minutes. It takes 3 to 4 hours to
generate a 5 ton load from the centrifuge which is then hauled to the
airport or stored on a drying slab located at the plant.
Air Dried - The 1961 International 10-wheel is also utilized for
hauling the air dried sludge since the haul distance is minimal. Once
the vehicle is loaded it travels only several hundred feet before it
off-loads.
o
The air drying beds collectively encompass an area of 300,270 ft
of actual available drying beds. Sludge is placed on the beds at 5
percent solids and 18 inches thick (i.e., 470 ton of dry solids). These
beds are cleaned three times per year which involves two men working
three 8-hour days, with the aid of a blade tractor and dump truck.
Landspreading System
The centrifuged dried sludge is dumped on the airport property by
the treatment plant personnel. At this point the sludge becomes the
responsibility of the airport to spread with their equipment. It is
then used as fill material around the airport. In some instances (when
weather conditions are unfavorable or when the airport is unable to take
the centrifuged sludge) it is stored on a concrete slab located near the
drying beds.
When sludge is utilized as fill material around the treatment
plant, it is dumped in piles for spreading by a tractor. The sludge is
later seeded. Even though the sludge is not covered with soil there
were no apparent problems from odors or flies.
Costs
Based on information provided by the City, the air drying operation
is the least costly of the two systems at $1 per dry ton. Because of
the maintenance and repair cost involved, the centrifuge operation is
more costly at $20 per dry ton of solids disposed. The above calculations
do not include the cost for landspreading the sludge. The City's
responsibility ends when the wastewater treatment plant deposits the
sludge on the airport's property. A more detailed cost analysis follows.
122
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COST FOR DISPOSAL OF AIR DRIED SLUDGE
Annual Capital Cost
Vehicle Depreciation 0
Equipment Depreciation 0
Total Annual Capital Cost
Annual Operating Cost
Personnel
Operator
Laborer
Hourly
$4
3
Wage
.98
.75
% Time Worked
4
4
Cost
$ 360
$ 270
$ 630
Fringe Benefits at 33 percent $ 210
Vehicle Maintenance and Operation
Parts and Supplies $ 60
Fuel, Oil and Lube $ 280
Insurance $ 10
$ 350
TOTAL ANNUAL OPERATING COST $1,140
TOTAL ANNUAL CAPITAL AND OPERATING COST $1,140
10% CONTINGENCY FACTOR1 $ 110
TOTAL ANNUAL COST $1,250
Total Annual Cost = $1,250 = $1 per dry ton
Total Sludge Hauled Annually 1,410 dry tons
1 A 10% contingency factor is added to cover such items as
administrative overhead.
123
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COST FOR DISPOSAL OF CENTRIFUGE DRIED SLUDGE
Annual Capital Cost
Vehicle Depreciation 0
Equipment Depreciation $26,200
2 - 1969 "Bird" centrifuges Cost: $180,000
Total Annual Capital Cost $26,200
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Operator $4.88 100 $10,150
Operator $4.88 100 $10,150
Lab Technician $5.00 25 $ 2,600
Foreman $5.80 5 $ 600
$23,500
Fringe Benefits at 33 percent $ 7,760
Vehicle Maintenance and Operation
Parts and Supplies $ 2,270
Fuel and Oil $ 490
Insurance $ 40
$ 2,700
Utilities and Other
Electricity $ 8,000
Centrifuge Maintenance
Maintenance, Parts and Labor $26,000
Contracted Balancing of Centrifuge Blades $20,000
$46,000
TOTAL ANNUAL OPERATING COST $87,960
TOTAL ANNUAL CAPITAL AND OPERATING COST $114,160
1 Stationary equipment was depreciated over 10 years at 8% interest
which amounts to a depreciation charge of $12.13 per $1,000 per month.
124
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10% CONTINGENCY FACTOR*
TOTAL ANNUAL COST
Total Annual Cost
11,420
$125,580
= $125,580
= $20 per dry ton
Total Sludge Hauled Annually 6,500 dry tons
2 A 10 percent contingency factor was included to cover such items
as administrative overhead.
125
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SHEBOYGAN, WISCONSIN
The City of Sheboygan, Wisconsin is a community of approximately
50,000 population, located On the shore of Lake Michigan. The City's
sewage treatment plant utilizes vacuum filtration followed by incineration
of raw sludge and, in addition, utilizes anaerobic digestion followed
by direct application of liquid sludge to farmland.
Person Contacted;
Mr. William Stubbe
Superintendent
Sewage Treatment Plant
3333 Lakeshore Drive
Sheboygan, Wisconsin 53081
Telephone: (414) 457-4713
Site Description
For the past four years the City has landspread its liquid sludge. In
1974, portions of 13 farms received sludge between the months of December
and March. p For this operation the City contracted with a septic tank
cleaning firm to locate utilization sites, and haul and spread the liquid
sludge. Sludge which is vacuum filtered is incinerated in the City's
fluid bed sludge incinerator.
General Information
The sewage treatment plant was built in 1937 and expanded several
times to include secondary trickling filters, vacuum filters, flash
dryers and a fluid bed incinerator. The plant employs 15 full time personnel.
Industrial contribution to the plant is estimated to be 25 to 40 per-
cent of the plant solids. The largest contributing industry is a leather
tannery which discharges a heavy solids load. There are 21 plants which
contribute over 10,000 g/d which include a refuse incinerator, a plastics
plant and metal finishing plants.
During 1974, the treatment plant disposed of 10,618,000 gallons of
sludge. Of this, 4,618,000 gallons at 3 to 4 percent solids were hauled
for field spreading. The remaining 6,000,000 gallons were vacuum filtered
to 21 to 24 percent solids and incinerated. The treatment plant design
capacity is 22 MGD with an average daily flow of 10 MGD. The effluent is
discharged into Lake Michigan. The population equivalent based on 0.17 Ibs
BOD/cap/day is approximately 120,000.
Sewage Sludge Composition
Table 1 presents data relative to the metals content of the liquid
sludge.
126
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Transport System
The City currently liquid hauls about 45 percent of its sludge.
Sludge is only hauled when crops are off the fields and field conditions
are such that the soil will not be compacted by the heavy trucks. As a
result, sludge is normally hauled for about two months between December
and March. The liquid sludge is hauled at 3 to 4 percent solids. This
method of disposal has been used for the past four years. All hauling
and spreading is handled by a contractor at a rate of $.0165/gallon.
The City's secondary digesters, which were built in 1937 and 1941,
are used only for storage of sludge. The combined capacity of these
digesters is 1,000,000 gallons.
All vacuum filtered sludge is incinerated.
Landspreading System
Little information.on the landspreading system was available since
the operation was contracted. The contractor uses an injection system
to apply the sludge to the land. The application rate is .94 gallons/ft.
or 6 dry tons/acre. Each 3,000 gallon load covers an area 400 feet long
by 8 feet wide. The principal crop grown on the treated soils is corn.
Cost
Based en operating information provided by the City, the cost for
disposal of liquid sludge is $125 per dry ton. This is a high cost, but
is a direct result of the high contract cost for transportation and
disposal. The cost for the City to vacuum filter and dispose of residue,
excluding incineration costs, is $380 per dry ton. This cost is very
high because of depreciation costs of over $100,000, chemical costs of
nearly $84,000 and personnel costs of over $60,000.
127
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Total Annual Capital Cost $0
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Superintendent $7.54 1 $ 160
$ 160
Fringe Benefits at 40 percent $ 60
Vehicle Maintenance and Operation
Contract Hauling $76,200
TOTAL ANNUAL OPERATING COST $76,420
TOTAL ANNUAL CAPITAL AND OPERATING COST $76,420
10 PERCENT CONTINGENCY FACTOR1 $ 7,640
TOTAL ANNUAL COST $84,060
Total Annual Cost = $84,060 = $125 per dry ton
Total Sludge Hauled Annually 670 dry tons
1 A 10 percent contingency factor is added to cover such items as
administrative overhead.
128
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COST FOR VACUUM FILTRATION AND RESIDUE DISPOSAL EXCLUDING INCINERATION
Annual Capital Cost
Vehicle Depreciation
1968, Ford Dump Truck, Cost: $9,000
Equipment Depreciation
Building Depreciation
Total Annual Capital Cost
Annual Operating Cost
$ 1,530
$60,670
$40,520
$102,720
Personnel
Hourly Rate
% Time Worked
Cost
Operator $5.19
Operator 4.91
Operator 4.91
Operator 4 . 91
Foreman 5.41
Superintendent 7.54
100
100
100
75
30
14
$10,210
10,210
10,210
7,660
3,380
2,200
Fringe Benefits at 40 percent
Vehicle Operating and Maintenance
Fuel and Oil
Vacuum Filter Operation
Repair
Chemicals
Utilities
Electricity
TOTAL ANNUAL OPERATING COST
$43,870
$17,550
170
$11,260
83,990
13,000
$169>840
1 Vehicles were depreciated over 8 years at 8 percent interest
which amounts to a depreciation charge of $14.14 per $1000 per month.
2 Equipment was depreciated over 10 years at 8 percent interest
which amounts to a depreciation charge of $12.13 per $1000 per month.
3 Buildings were depreciated over 20 years at 8 percent interest
which amounts to a depreciation charge of $8.36 per $1000 per month.
129
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TOTAL ANNUAL CAPITAL AND OPERATING COST $272,550
10 PERCENT CONTINGINCY FACTOR4 27,260
TOTAL ANNUAL COST $299,810
Total Annual Cost = $299,810 = $380 per dry ton
Total Sludge Processed Annually 790 dry tons
4 A 10 percent contingency factor is added to cover such items as
administrative overhead.
130
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Table 1
Liquid Sludge Analysis*
Cr 5,000 ppm
Zn 1/400 ppm
Cd 13 ppm
Ni 130 ppm
Cu 13° ppm
pb 260 ppm
* Chemical laboratory results are all on a dry weight basis.
131
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SPRINGFIELD, OHIO
The City of Springfield, Ohio is a community of approximately
86,000 population, located between Dayton and Columbus, Ohio. The
City's treatment facility consists of a trickling filter plant with
secondary anaerobic digestion. The effluent receives post chlorination
prior to discharge into the Mad River. Sludge is either liquid hauled
to farm land, allowed to air dry in lagoons for use by private citizens,
or used by the City as a top dressing on filled land.
Persons Contacted
Mr. R. J. Collins
Chief of Operations
Telephone: (513) 399-6841
Mr. Michael Justice, Superintendent
Water Pollution Control Department
965 Dayton Avenue
Springfield, Ohio 45501
Telephone: (513) 322-4949
Site Description
Liquid Sludge Disposal - The City hauls liquid sludge to one of
several different site locations. In 1974, all liquid sludge was
applied to about 75 acres. The soil is predominantly Miami silt loam.
Farms for sludge application are selected on the basis of distance from
the plant, access to fields, and distance from fields to dwellings.
Lagoon Dried Sludge - When weather, field conditions, or availa-
bility of truck drivers will not permit hauling of liquid sludge to farm
land, it is pumped to one of several large lagoons for air drying. The
lagoons are 5 to 6 feet deep and cover a total area of about 4 acres.
However, the City prefers to only fill them to a depth of about two feet
so they dry faster. After the sludge has dried, it is used as a top
dressing on land that has been filled. A small amount is also stock-
piled near a plant gate for private citizens to obtain for home gardening.
General Information
The City estimates the industrial input into the treatment facility
to be approximately 33 percent of the total flow. The design capacity
of the treatment plant is 25 MGD, with an average daily flow of 20 MGD.
The BOD population equivalent is 87,203. This figure is only slightly
over the population served figure of 86,000 because the major industrial
input is as cooling water from assembly plants.
132
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All treatment plant sludge receives secondary digestion prior to
field application or being placed in lagoons. The total annual quantity
of sludge is 5,373,000 gallons at 8 percent solids. Screenings amount
to 240 cubic feet per year, which are incinerated at the plant. Grit
amounts to an additional 240 cubic feet per year, which is dumped into
the lagoons.
Sewage Sludge Composition
Sludge analysis, as provided by the City, is shown in Table 1.
Transport System
Liquid Sludge - The City currently liquid hauls about 30 percent of
its sludge. The decision to liquid haul or lagoon is based on manpower
available for hauling sludge, availability of fields for spreading, and
weather conditions. In general, the City liquid hauls an average of one
day per week with two 3,000 gallon tank trucks. An average of 10 loads
per day are.handled on haul days. In 1974, 520 dry tons of sludge were
hauled. The majority of the sludge is hauled to two farms, each about
four miles from the plant. The two tank trucks used in the operation
were purchased in 1969 and 1973, at a cost of $11,269 and $14,402,
respectively. The trucks are equipped with a cab controlled valve and
gravity flow spread bar.
Lagooned Sludge - At times, when sludge needs to be removed from
the plant but conditions are not favorable for liquid hauling, sludge is
pumped into one of three large lagoons. The lagoons are sloped to the
far end from the inlet, with an average depth of five to six feet.
Normal procedure is to fill the lagoons to a depth of about two feet to
allow for faster drying. In 1974, a total of 3,805,000 gallons of
sludge at 8.3 percent solids were added to the lagoons and 4,880 cubic
yards at 60 percent solids were removed. A tracked, 1 1/2 cubic yard
bucket loader, purchased in 1969 for $11,496, is used exclusively to
load sludge from the lagoons into dump trucks. Two 10 cubic yard dump
trucks are used 95 percent of the time for transporting lagooned sludge.
They were purchased in 1969 and 1974 at a cost of $10,800 and $15,843,
respectively. Most of this sludge is hauled to City land where it is
used as a top dressing.
Landspreading System
Liquid Sludge - The liquid sludge is applied by gravity flow
directly from the rear of the truck. A spreader pipe is used to give an
even application over about an eight foot width. In 1974, 1,568,000
gallons of sludge were applied to 75 acres for an average application
rate of 7 dry tons per acre. Most of the land which receives sludge is
tilled and planted with corn or wheat crops. No sludge is spread within
133
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500 feet of a dwelling. To date, there have been no complaints about
the operation.
Costs
In 1974, the City disposed of 520 dry tons of liquid sludge on farm
land at a cost of $22 per dry ton. In comparison, the City lagoon dried
and disposed of 2,180 dry tons of sludge at a cost of $9 per dry ton in
1974. A breakdown of the costs included in this analysis is attached.
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation-1- $4,360
1969 International, cost: $11,300
1973 International, cost: $14,400
Total Annual Capital Cost $4,360
Annual Operating Cost
Personnel Hourly Rate
Driver
Chemist
Superintendent
$5.00
10.00
% Time Worked Cost
19 $2,000
4 800
400
$3,200
Fringe Benefits at 40 percent $1,280
Vehicle Maintenance and Operation
Fuel and Oil $ 450
Repairs 1,000
Insurance 80
Utilities
Electricity for Pumping 10
Pumping Facility Maintenance 10
TOTAL ANNUAL OPERATING COST $6,030
TOTAL ANNUAL CAPITAL AND OPERATING COST $10,390
10 PERCENT CONTINGENCY FACTOR $1,040
TOTAL ANNUAL COST $11,430
Total Annual Cost = $11,430 = $22 per dry ton
Total Sludge Hauled Annually 520 dry tons
1 Vehicles were depreciated over 8 years at 8 percent interest, which
amounts to a depreciation charge of $14.14 per $1,000 per month.
2 A 10 percent contingency factor is added to cover such items as
administrative overhead.
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COST FOR DISPOSAL OF LAGOON DRIED SLUDGE
Annual Capital Cost
Vehicle Depreciation1 $6,460
1969 1 1/2 yd3 bucket loader, cost: $11,496
1969 Dump Truck, cost: $10,800
1974 Dump Truck, cost: $15,843
Stationary Equipment Depreciation $0
Building Depreciation $0
Total Annual Capital Cost $6,460
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Driver $5.00 34 $4,050
Chemist 10.00 9 1,820
Superintendent 350
$6,220
Fringe Benefits at 40 percent $2,490
Vehicle Maintenance and Operation
Fuel and Oil $470
Repairs $2,000
Insurance 150
TOTAL ANNUAL OPERATING COST $11,330
TOTAL ANNUAL CAPITAL AND OPERATING COST $17,790
10 PERCENT CONTINGENCY FACTOR2 $1,780
TOTAL ANNUAL COST $19,570
Total Annual Cost = $19,570 = $9 per dry ton
Total Sludge Hauled Annually 2,180 dry tons
1 Vehicles were depreciated over 8 years at 8 percent interest, which
amounts to a depreciation charge of $14.14 per $1,000 per month.
2 A 10 percent contingency factor is added to cover such items as
administrative overhead.
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TABLE 1
Springfield, Ohio, Sludge Analysis (ppm)
(dry weight basis)
Date Cd
2/73
5/73
3/74 5
1/75 88
3/75 17
8/75
12/75 52
Cr
277
400
62
877
477
1,712
1,530
Cu
105
102
32
17
15
170
170
Ni
34
42
45
75
69
62
152
Pb
105
115
31
154
—
—
206
Zn
108
1,492
106
584
226
—
830
137
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TOLEDO, OHIO
Toledo, Ohio is located in Northwestern Ohio approximately 50 miles
south of Detroit, Michigan. 'The activated wastewater treatment plant
serves a population of approximately 500,000. Design capacity of the
plant is 100 MGD and average daily flow is 92 MGD. Approximately 30 percent
of the collection system is combined sanitary and storm sewers, the remainder
is sanitary only. Dewatered sludge is routinely hauled to farmland and
some experiments with liquid sludge have been conducted.
Persons Contacted
Mr. M. Brandt Tennant
Commissioner
Division of Water Reclamation
Bay View Park
Toledo, Ohio 43611
Telephone: (419) 247-6545
Mr. Gerald Baumgartner
Divison of Water Reclamation
Bay View Park
Toledo*, Ohio 43611
Telephone: (419) 247-6545
Site Description
The largest portion of the sludge is handled under contract with Soil
Enrichment Materials Corporation (SEMCO). This firm has contracted for
867 acres of farmland. To date only 415 acres have received sludge. The
land is actively farmed and the principal crops grown are corn, soybeans,
wheat and oats.
The City also spreads dewatered sludge on its own land. Sludge is
applied twice annually to land adjacent to the House of Correction. Of
the 155 acres available, 30 acres have received 2 applications while
another 30 acres have received one application. Corn, hay, and soybeans are
grown on this land.
There have also been experimental landspreading trials for liquid
sludge. These experiments have been conducted by individuals. The City
personnel felt that high trucking costs would make the landspreading of
liquid sludge economically unattractive, but mechanically, a more manageable
system. Barging or rail haul are under consideration. Experiments are also
contemplated to assess the economics and feasibility of composting.
General Information
The original facility at this location was a. pump station constructed in
1916. Primary treatment was built during the late 1920's with anaerobic diges-
ters. Secondary treatment was added in 1959. In 1968 vacuum filters were
138
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added and landfilling of the sludge was begun. Prior to 1968 sludge
lagoons were used. In 1973 the present landspreading programs were
initiated. Additional capacity was added to the secondary treatment
system in 1974.
A solids content ranging from 6 percent to 9 percent is obtained
from the two-stage anaerobic digesters. The vacuum filters increase the
solids content to about 20 percent. Between 200 and 250 tons per day
of filter cake are produced six days per week.
Sewage Sludge Composition
Characterization of the sludge cake is attached.
Transport System
The sludge is dewatered to 20 percent solids on coil vacuum filters.
City personnel use a single axle tractor to position the 30 cubic yard
trailers, under a conveyor belt for loading. (The trailers are owned
by a contractor). After the trailers are loaded they are positioned in
a parking area for the trucking firm which delivers them to the SEMCO
site or the City's site at the House of Correction's Farm. The haul
distance to the SEMCO site is 45.2 miles one-way requiring a round trip
driving time of 2.5 hours. The distance to the House of Correction's
Farm is 34 miles each way. At the landspreading sites the trailers are
unloaded at a central stockpiling location.
Landspreading System
SEMCO has a contract for 867 acres in Wood County which can be used for
sludge application at no cost to the farmer. A compacted crushed limestone
pad has been prepared at the site for stockpiling the sludge while it
awaits application to the fields. When weather and cropping conditions will
permit, sludge is loaded with a 4-yard loader into a farm manure spreader
or a Field Gymmy for application to the land. The Field Gymmy has an
8-yard hopper box, high flotation tires and a rear spinner assembly for
spreading. This piece of equipment is preferred over the manure spreader
because it compacts the field less, distributes the load more evenly and
is able to operate in wetter fields than the tractor-drawn spreader. The
normal application rate is 10 dry tons per acre per year but varies from
5 to 30 dry tons per acre.
The landspreading at the House of Correction is done in a similar
fashion. The City also owns a Field Gymmy and keeps a front end loader
at the site for loading. Because of cropping practices used on this farm,
landspreading is done'only in the spring and fall. The application rate is
between 10 and 13 dry tons per acre per year.
139
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Costs
The annual sludge treatment and handling costs are estimated to
be between 40 and 50 percent of plant operating costs. The contract with
SEMCO separates the hauling and spreading costs. The firm iszpaid $2.92
per wet ton for hauling and $3.24 per wet ton for spreading. Based on
operating information provided by the City of Toledo, the City is current-
ly disposing of its vacuum filtered sludge at a cost of $117 per dry ton.
The cost of dewatering accounts for about $77 per dry ton. The major
cost factors for dewatering are dept retirement of about $500,000 and labor,
chemical and power costs for operating the'vacuum filters of about $730,000.
A breakdown of costs that were available from the City is attached.
140
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COST FOR DISPOSAL OF VACUUM FILTERED SLUDGE
Annual Capital Cost
Debt Service on Vacuum Filters and
City Owned Trucks $500,000
Total Annual Capital Cost $ 500,000
Annual Operating Cost
Labor, Chemicals and Power to
Operate Vacuum Filters $730,000
Sludge Hauling (contract @ $2.92/wet ton) 237,000
Sludge Spreading (contract @ '$3.24/wet ton) 263,000
TOTAL ANNUAL OPERATING COST $1,230,000
TOTAL ANNUAL CAPITAL AND OPERATING COST $1,730,000
10% CONTINGENCY FACTOR 1 $ 173,000
TOTAL ANNUAL COST $1,903,000
Total Annual Cost = $1,903,000 = $117/dry ton
Total Sludge Hauled Annually 16,250 dry tons
1 A 10% contingency factor is added to cover such items as administrative
overhead.
141
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SLUDGE CAKE CHARACTERIZATION
TOLEDO WATER RECLAMATION PLANT
PARAMETER*
% Solids
% Volatile Solids
% Fixed Solids
% T 0 C
PH
Density
PCB
HEAVY METALS
Aluminum
Arsenic
Beryllium
Boron
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Selenium
Sodium
Zinc
NUTRIENTS
% Nitrogen-Total
% Nitrogen-Organic
% Nitrogen-NH3
% Nitrogen NO -NO_
% Phosphorus-Total
Phosphorus-Water
Soluble
% Potassium
RANGE
14.5 -
38 -
62 -
16 -
10 -
1.05 -
0.5 -
2/200 -
3 -
0.5 -
5.6 -
23 -
60,000 -
47 -
420 -
22,000 -
340 -
6,700 -
870 -
0.01 -
41 -
1 -
83 -
1,850 -
1.72 -
1.23 -
0.002 -
6 -
2.13 -
40 -
0.027 -
27
50
50
18
13
1.09
5
53,500
17
1
16.1
41
135,000
1,120
1,570
101,000
720
22,000
35,000
2.2
696
67
910
4,050
2.42
2.38
0.64
60
2.95
240
0.35
AVERAGE
20
44
56
17.4
12
1.067
2
AVERAGE POUNDS
PER DRY TON
16,000
12
0.7
7.5
26
102,000
676
650
71,000
526
10,300
10,400
1.1
450
19
690
2,740
2.08
1.48
0.222
30
2.5
120
0.17
32
0.024
0.0014
0.015
0.052
204
1.35
1.3
142
1.05
20.6
20.8
0.002
0.81
0.038
1.38
5.48
41.6
29.6
4.4
0.06
50
0.24
3.4
* ppm unless otherwise indicated
142
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YORK, PENNSYLVANIA
York, Pennsylvania is located in the southeastern part of the state,
about 45 miles straight north of Baltimore, Maryland. The City's waste-
water treatment plant utilizes activated waste treatment and serves a
population of 115,000. Sludge from the plant is transported in both
liquid and dewatered (vacuum filtered) state to farm land. Design capacity
of the plant is 18 MGD. The average daily flow is 16 MGD.
Person Contacted
Mr. Harvey Bortner
Superintendent of Wastewater Treatment
Department of Public Works
Yprk, Pennsylvania
Telephone: (717) 854-9333
Site Description
The City is presently utilizing 40 farms having a collective acreage
of over 4,490 acres. Most of the land utilized is actively farmed with
corn being the principal crop. Two farmers leave alternating strips of
their fields fallow for sludge disposal in bad weather. These strips
are planted in grasses.
General Information
The wastewater treatment plant was constructed in 1916 and upgraded
in 1954 to activated sludge. Design capacity of the plant is 18 MGD
with an average daily flow of 16 MGD. Sludge in the plant is anaero-
bically digested and then stored in an elutrification tank for vacuum
filtration. Liquid sludge for the tank trucks is drawn directly from
the secondary digesters.
The anaerobically digested sludge is about 4.5 percent solids. A
portion of the sludge is dried by vacuum filtration which results in a
sludge having a 16 percent solids content. The total dry weight of
sludge leaving the plant in 1975 was 2,330 tons. Of this 1,360 dry tons
were as a liquid and 970 dry tons as vacuum filtered sludge. There are
23 major industries which contribute an estimated 50 percent of the
flow.
The City is presently initiating action to proceed with the findings
of an engineering study conducted several years ago which recommended
that a sludge incinerator in the plant be upgraded to meet present
emission standards so it can once again handle all the generated sludge.
Sewage Sludge Composition
The analysis of York's sludge, as shown in Table 1, indicates that the
sludge is high in Cd.
143
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Transport System
Sludge is normally removed from the plant five days a week regardless
of weather conditions. The .vacuum dried sludge is hauled in two five
cubic yard dump trucks to two farms, one three miles from the plant and
the other six miles.
Liquid sludge is hauled to one of 40 farms five days a week, weather
permitting. The City has five 2,500 gallon tank trucks. Of these, one
is standby and the other four average five loads each per day. The
sites are an average of about 20 miles round trip distance from the
plant with a driving time of about one hour.
The apparatus for loading the trucks consists of a belt conveyor
from the vacuum filters to the dump trucks and a gravity flow stand pipe
for the liquid sludge.
Landspreading Operation
The dried sludge is dumped in piles in the fields for later spread-
ing with a dozer by the farmer. Normally sludge has to be stockpiled on
a portion of t^ie treatment plant property for about two months of the
year when it is impossible to get into the fields. The sludge is then
later loaded on other city trucks and hauled to the farms. Only two
farms receive dried sludge.
The liquid sludge trucks are equipped with pumps which spray the
sludge over a 10 foot strip, starting about 5 feet from the truck.
Application is very even and unloading time is about five minutes.
During wet weather, sludge is applied to grass land or along graveled
lanes. Edges of fields along lanes often receive as many as 30 to 40
applications per year. Other fields receive one to five applications
per year, depending upon the crop. The heaviest single application
applied is four loads per acre (i.e., 2 dry tons). All fanners except
the two who will take the dried sludge are charged $2 per tank truck
load for the sludge. Income from this in 1974 was $1,384. The only
monitoring of sludge utilization sites is being done by the U.S. Department
of Agriculture's Agricultural Research Service.
Costs
The treatment plant was completed in 1954. Since buildings were
depreciated over 20 years and stationary equipment over 10 years, there
are no depreciation costs for these items. Based on actual operating
information provided by the City, detailed costs were determined for the
annual capital and operating expenses for liquid haul and vacuum filtration
and hauling of sludge. The total cost per dry ton of liquid sludge
hauled was $73 and for vacuum filtration $165. With the vacuum filtered
sludge, the cost of dewatering accounts for about $140 per dry ton. The
major reasons for high dewatering costs are that repairs on the older
vacuum filters cost about $60,000 and labor to operate them cost about
$53,000. A detailed breakdown is attached.
144
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COST FOR DISPOSAL OF LIQUID SLUDGE
Annual Capital Cost
Vehicle Depreciation1 $8280
1964 RIO Tank Truck
1967 RIO Tank Truck
1968 Diamond T Tank
Truck, cost: $16,148
1970 International Tank
Truck, cost: $16,173
1970 International Tank
Truck, cost: $16,528
Stationary Equipment Depreciation $0
Building Depreciation $0
Total Annual Capital Cost $8,280
Annual Operating Cost
Personnel Hourly Rate %^ Time Worked Cost
4 Truck Drivers $4.25 100 $35,360
Auto Mechanic 4.54 54 5,060
Laboratory Assistant 5.77 5 600
Chief Operator 6.00 23 2,810
Supervisor 7.50 5 720
$44,550
Fringe Benefits at 40 percent $17,820
Vehicle Maintenance and Operation
Repairs $ 9,670
Fuel and Oil 8,010
Insurance 2,890
TOTAL ANNUAL OPERATING COST $82,940
TOTAL ANNUAL CAPITAL AND OPERATING COST $91,220
1 Vehicles were depreciated over 8 years at 8 percent interest,
which amounts to a depreciation charge of $14.14 per $1,000 per month.
145
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2
10 PERCENT CONTINGENCY FACTOR $ 9,120
INCOME FROM SALE OF LIQUID SLUDGE $ 1,380
TOTAL ANNUAL COST $98,960
Total Annual Cost = $98,960 = $73 per dry ton
Total Sludge Hauled Annually 1,360 dry tons
2 A 10 percent contingency factor is added to cover such items as
administrative overhead.
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COST FOR DISPOSAL OF VACUUM FILTERED SLUDGE
Annual Capital Cost
Vehicle Depreciation $3,150
1970 Chevrolet Dump Truck, cost: $6,808
1974 Diamond T Dump Truck, cost: $11,708
Plant Equipment Depreciation $0
Total Annual Capital Cost $3,150
Annual Operating Cost
Personnel Hourly Rate % Time Worked Cost
Truck Driver $4.25 100 $8,840
Auto Mechanic 4.54 19 1.770
2 Vacuum Filter
Operators 503 100 20,920
Vacuum Filter
Laborer 3.86 100 8,030
Vacuum Filter
Laborer 3.73 100 7,760
Laboratory Assistant 5.77 5 600
Chief Operator 6.00 2.5 310
Supervisor 7.50 5 720
$48,950
Fringe Benefits at 40 percent $19,580
Vehicle Maintenance and Operation
Repairs $ 2,100
Fuel and Oil 430
Insurance 1,130
Vacuum Filter Maintenance
Chemicals $ 9,590
Parts and Repair 60,000
Utilities $1,000
1 Vehicles were depreciated over 8 years at 8 percent interest,
which amounts to a depreciation charge of $14.14 per $1,000 per month.
147
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TOTAL ANNUAL OPERATING COST $142,780
TOTAL ANNUAL CAPITAL AND OPERATING COST $145,930
10 PERCENT CONTINGENCY FACTOR $ 14,590
TOTAL ANNUAL COST $160,520
Total Annual Cost = $160,520 = $165 per dry ton
Total Sludge Hauled Annually 970 dry tons
2 A 10 percent contingency factor is added to cover such items as
administrative overhead.
148
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TABLE 1
Sludge Sample from York, Pennsylvania
Dry Weight 4.4 percent
Ash 39.0 percent
Zn 3,260 mg/kg
Cu 770 mg/kg
Ni 200 mgAg
Cd 65.1 mg/kg
Pb 960 mgAg
Cd/Zn 2.0 percent
Zn (Eq) 5,400
Values reported as mg/kg are on a dry weight basis,
ya!542
SW-619
149
•U.S. GOVERHMENT PRINTING OFFICE 1977 0-260-880/103
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Region I
John F. Kennedy Bldg.
Boston. MA 02203
(617) 223-7210
Region II
26 Federal Plaza
New York. NY 10007
(212) 264-2515
Region III
6th & Walnut Sts.
Philadelphia. PA 19106
(215) 597-9814
Region IV
345 Courtland St., N.E.
Atlanta. GA 30308
(404) 881-4727
Region V
230 South Dearborn St.
Chicago. IL 60604
(312) 353-2000
Region VI
1201 Elm St.. First International Bldg.
Dallas. TX 75270
(214) 749-1962
Region VII
1735 Baltimore Ave.
Kansas City, MO 64108
(816) 374-5493
Region VIII
1860 Lincoln St.
Denver, CO 80203
(303) 837-3895
Region IX
100 California St.
San Francisco, CA 94111
(415) 556-2320
Region X
12006th Ave.
Seattle, WA 98101
(206) 442-5810
U.S. ENVIRONMENTAL PROTECTION AGENCY
Regional Offices
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