-------
early in the process. Area residents also may assist in
identifying candidate sites.
4.4.2 Step 2: Site Scoring and Ranking
This section describes a quantitative approach to scor-
ing and ranking sites. This approach involves!defining
objectives, defining criteria to meet those objectives,
specifying the relative importance of the objectives and
criteria, and then assigning scores—weighted according
to the relative importance of each criterion and its overall
objective—that indicate the ability of each candidate site
to fulfil each criterion. The individual scores are then
added to produce a total score for each site that can then
be used to rank the sites.
This approach may be more extensive than necessary
for small sludge surface disposal sites. In such cases, a
qualitative system (e.g., using terms such as suitable,
marginally suitable, and not suitable in lieu of numerical
ratings) may be more appropriate. Table 4-8 illustrates
how the site scoring and ranking process described
below was applied to the four candidate sites for Study
Area X that remained after the less desirable of the 13
original sites were eliminated during Step 1-6 based on
regulatory, technical, and economic considerations.
Step 2-1: Determine attainable objectives for the site
based on the following considerations:
• Technical considerations:
- Haul distance
— Site life and size
- Topography
- Soils and geology
- Ground water
— Soil quantity and suitability
- Vegetation
- Environmentally sensitive areas
- Archaeological or historical significance
- Site access
- Land use
• Economic considerations
• Public acceptance considerations
Column 1 of Table 4-8 shows some examples of objec-
tives.
Step 2-2: List these objectives by order of importance.
Assign a value (e.g., on a scale of 1 to 10,1 to 100, or
1 to 1,000) to each objective to reflect its relative impor-
tance. (Column 2 of Table 4-8 rates the Column 1 objec-
tives on a scale of 1 to 1,000.) Discard any objectives
that appear insignificant in light of a very low rating
relative to other objectives.
Step 2-3: For each objective, develop criteria to meas-
ure the ability of a site to attain the objective. Column 3
of Table 4-8 lists criteria for the Column 1 objectives.
Step 2-4: Assign a numerical value on a scale of 1 to
10 to the criteria for each objective to reflect their relative
ability to contribute to the attainment of the objective,
rather than their individual significance. Add the values
assigned to all criteria for a particular objective. Column
4 of Table 4-8 shows the relative values assigned to the
Column 3 criteria and the addition of values for the
criteria within each objective. '"
!•
Step 2-5: For each criterion, multiply its numerical
value by the overall rating for the objective and divide
by the total of all criteria values within that objective to
get the maximum score that may be assigned to that
criterion (see Column 5 of Table 4-8). For example, to
obtain the maximum score for the first criterion ("ground-
water pollution hazard") of the first objective ("the site
must not endanger public health") listed in Table 4-8, the
following calculation was performed:
10x1,000
34
= 294
The maximum score for each criterion is thus a fraction
of the total score for the objective in direct proportion to
the criterion's relative ability to contribute to attainment
of the objective. The maxjmum scores for all criteria
within an objective should total to the relative overall
rating for the objective (Column 2 of Table 4-8).
Step 2-6: For each criterion, assign a rating from 1 to
10 to each site to indicate the site's potential to satisfy
that criterion. (If a site cannot meet an objective, the site
should be eliminated from further consideration.) Columns
6a, 7a, 8a, and 9a show values assigned for sites 1, 2, 3,
and 4, respectively. These values must now be weighted
to reflect the relative importance of the objective and
the individual criterion. This is done by multiplying the
rating by the maximum score for that criterion (Column
5 of Table 4-8) and then dividing the total by the relative
ability of the criterion to fulfil the objective (Column 4 of
Table 4-8). For example, a rating of 7 was assigned to
the ability of site S-5 to satisfy the first criterion for the
first objective. The following calculation was then per-
formed to yield a weighted score of 206:
7x294
10
= 206
Columns 6b, 7b, 8b, and 9b of Table 4-8 show the
weighted scores calculated for the four candidate sites
in Study Area X.
51
-------
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This scoring system works best if all sites are compared
one criterion at a time. Different specialists should be
used to score the sites under criteria involving their area
of expertise. For example, land use planners should be
used to score those criteria related to land use.
Step 2-7: For each site, add all the individual scores to
get a total score for the site (see bottom row of columns
6b, 7b, 8b, and 9b in Table 4-8). These totals can be
compared to rank the overall and relative suitability of the
various candidate sites. For example, the sites in Table
4-8 would be ranked S-11, S-13, S-5, and S-10 in order
from most suitable to least suitable for a sludge surface
disposal site considering all objectives and criteria.
4.4.3 Step 3: Site Investigation
Step 3-1: Investigate four to six candidate sites and
identify site-specific problems. Field investigations (see
Chapter 6) may be appropriate to supplement informa-
tion from existing sources. In particular, it may be desir-
able at this stage to perform initial hydrogeological
investigations on the primary candidate sites. This in-
vestigation can begin with a preliminary reconnaissance
visit to each site to observe aspects such as:
• Site topography
• General geomorphic features
• Bedrock exposure
• Degree of soil development
• Seeps and springs
• Potentially impacting activities (e.g., clear cutting)
• Vegetation types
• Wetlands potential
To perform a hydrogeological investigation that involves
drilling, an option for the site must be obtained. Because
option negotiations are not always successful, it may be
necessary to pursue negotiations for two to three times
as many sites as the evaluation team wishes to actually
investigate.
Performance of a conceptual design (see Step 4-1), and
development of a refined cost estimate based on this
design, may also be appropriate for some or all of the
candidate sites during the site investigation stage.
Step 3-2: Rescore and rank sites based on results.
Once the results of the hydrogeological investigation
have been obtained, the ranking of candidate sites
should be reexamined and modified as appropriate to
incorporate the site-specific results obtained during the
hydrogeological investigation. Any sites that are unsuit-
able hydrogeologically should be eliminated from further
consideration.
Step 3-3: If required or appropriate, input site selection
findings of top site(s) into an environmental impact re-
port. Environmental impact reports are required in cer-
tain states (e.g., New York). Environmental impact
reports may also be appropriate under certain circum-
stances such as for environmentally sensitive sites or
for sites where there is a high level of public concern.
Step 3-4: Obtain additional public input.
4.4.4 Step 4: Final Selection
Step 4-1: For each candidate site, develop a concep-
tual design that is compatible with sludge and site char-
acteristics (see Chapter 3) (or review and revise the
conceptual designs if they were already developed un-
der Step 3-1). A conceptual design should first establish
site buffers, site facilities, site volume, site life, and the
overall landfill footprint. Once these have been estab-
lished, a preliminary excavation plan and a final grading
plan can be developed using conventional civil engi-
neering and computer-aided design and drafting
(CADD) tools. The designer can then readily determine
the landfill capacity (or airspace) by using CADD tools
to compare the excavation and final grading plans. The
capacity calculation can in turn be used to determine the
soil balance, the overall site life, and other site features.
CADD tools can also be used to delineate the shape of
the surface disposal site to better enable public percep-
tion and interpretation. Finally, the conceptual design
can serve as the basis for a cost estimate. A detailed
preliminary cost estimate can be developed to address
capital costs (liner systems, excavation, roads, facilities,
etc.) and operating costs (equipment, personnel,
leachate treatment/disposal, etc.).
Step 4-2: Evaluate the options for using the closed site
and select the most appropriate use for each candidate
site.
Step 4-3: Evaluate life cycle costs in detail for each
candidate site.
• Site capital cost
• Site operating cost
• Hauling cost
Tables 4-9 and 4-10 show the capital and operating cost
estimates for the four sites under final consideration at
Study Area X. (In this example, hauling costs are in-
cluded as part of operating costs.) The total cost was
calculated using the following method to determine pro-
rated cost ($/yd3) over the life of the site based on the
projected sludge volumes.
53
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Table 4-9. Capital Cost Estimates for Four Study Area
Description
Land Acquisition
Number of acres
Cost per acre
Purchase price
Site Development Costs
Initial site preparation
Clearing and grubbing
Fence and gate
Access roadway (onsite)
Leachate collection system
Storm water management
Reconstruct primary access roadway
Equipment storage shed
Utilities
Monitoring
Subtotal
Engineering Surveying Subsurface Exploration and
Permits (20%)
Contingency (1 0%) of Land Acquisition and Site
Development Costs
Equipment
Backhoe Loader
Total Capital Cost
Estimated Site Life (yrs)
Unit Cost ($/yef) based on 18,000 ycf/yr
Annual Unit Capital Cost 8% over Site Life ($/yo3)
X Candidate
S-5
20
6,600
132,000
100,000
240,000
20,000
16,000
4,000
30,000
—
30,000
4,000
8,000
621,600
124,000
62,000
180,000
987,600
10
5.49
0.89
Sites
Site
S-10
37
16,000
592,000
60,000
4,000
24,000
32,000
—
40,000
—
30,000
6,000
8,000
796,000
159,200
79,600
120,000
1,154,800
12
5.35
0.79
No.
S-11
25
4,000
1,000,012
60,000
6,000
20,000
6,000
50,000
30,000
—
30,000
4,000
8,000
314,000
62,800
31,400
180,000
588,200
10
3.27
0.53
S-13
30
16,600
498,000
80,000
10,000
6,000
24,000
—
60,000
200,000
30,000
6,000
8,000
922,000
184,400,
92,200
45,000
1,243,600
12
5.76
0.85
1 yd3
1 ac
0.7646 m3
0.4047 ha
Total Capital Costs =
Total Operation and =
Maintenance Costs
Total Unit Capital Cost =
Total Unit Operation =
and Maintenance
Cost
Land Acquisition Cost +
Site Development Cost +
Engineering and
Contingency (20% + 10%
of land acquisition and
development costs) +
Equipment Purchase Cost
Site Operation and
maintenance Costs +
Sludge Handling Cost
Total Capital Cost/18,000
yd3/yr
Total Operation and
Maintenance Cost/18,000
yd3/yr
Annual Unit Capital
Cost ($/yd3)
Total Unit Annual
Cost ($/yd3)
Total Unit Capital Cost
($/yd3) amortized at 10%
over site life
Annual unit capital cost
($/yd3) + Annual Operation
Cost ($/yd3)
Step 4-4: Evaluate local government policies and ob-
tain public input. A public hearing may be scheduled to
receive final comments from local government officials
and the public.
Step 4-5: Select site and list alternative sites. In the
example Study Area X, the data affecting the final site
selection were summarized in a table (Table 4-11). Site
54
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Table 4-10. Operating Cost Estimates for Four Study Area X Candidate Sites
Site No.
Description
One full-time equipment operator: Cost includes an
allowance of 30% for fringe benefits
Equipment operation and maintenance
Site operation and maintenance
Leachate haul costs
Cover material purchase
Temporary road surfacing, access,
cleaning
and highway
Ground-water monitoring samples
Subtotal of site costs
Sludge hauling cost
Total operating cost/yr
Unit cost ($/yo3) based on 18,000 ycP/yr
Table
Map
Ref.
S-5
S-10
S-11
S-13
4-11. Final Site Selection
Site Name/Location
Alton Street Site
Hunter Road Site
Harrington Blvd. Site
Gilford Road Site
Scoring
System
Value
1,773
1,538
2,534
2,239
Type of
Surface
Disposal Site
Area fill mound
Wide trench
Area fill mound
Wide trench
S-5
$30,000
$30,000
$10,000
$2,000
$50,000
$40,000
$6,000
$168,000
$30,000
$198,000
$11.00
Proposed Final
Site Use
Open space
Return to natural
Pasture
Park
S-10
$30,000
$30,000
$10,000
—
$30,000
$4,000
$104,000
$300,000
$404,000
$22.44
S-11
$30,000
$30,000
$6,000
$2,000
$80,000
$30,000
$4,000
$182,000
$50,000
$232,000
$12.88
S-13
, $30,000
$30,000
$8,000
— •
$16,000
$4,000
$88,000
$150,000
$238,000
$13.22
Site Total Annual
Life Cost ($/yd3)a
10
state 12
10
12
yrs
yrs
yrs
yrs
11.89
23.23
13.41
14.07
Public
Acceptance
Ranking"
3
2
4
1
8 Sum' of annual capital costs (at 10 percent over site life) and operating costs.
b Provided from attitude survey taken at public meetings; lower numbers represent less opposition.
1 yd3 = 0.7646 m3
S-13 was selected based on its (1) top public accep-
tance ranking, (2) longer life, and (3) completed site use
as a needed park. Although site S-13 was not the top-
ranked site technically, it was technically acceptable.
Also, its cost was relatively high, but the operating
agency decided to absorb the extra cost due to the
obvious site benefits.
Step 4-6: Acquire site. The following options are avail-
able:
• Option to purchase and subsequent execution (await
site approval).
• Outright purchase (after site approval by regulatory
agency and local jurisdiction).
• Lease.
• Condemnation and/or other court action.
• Land dedication.
Purchasing a site is generally more advantageous than
holding a long-term lease because the managing
agency's responsibility normally extends well beyond
the site life. Certain advantages may also be gained by
leasing with an option to buy the site at the time of permit
approval. This option ensures that the land will be avail-
able when the facility planning process is completed. It
also allows time for the previous owner to gradually
phase out operations, if necessary.
4.5 References
1. Algermissen, ST., et al. 1990. Probabilistic earthquake and velocity
maps for the United States and Puerto Rico. Miscellaneous field
studies map MF-2120. Washington, DC: U.S. Geological Survey.
2. Algermissen, ST., et al. 1982. Probabilistic estimates of maximum
acceleration and velocity in rock in the contiguous United States.
Open-file report 82-1033. Washington, DC: U.S. Geological Survey.
55
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3. U.S. Army Corps of Engineers. 1989. Federal manual for identi-
fying and delineating jurisdictional wetlands: Cooperative techni-
cal publication. Federal Interagency Committee for Wetland
Delineation, U.S. Army Corps of Engineers, U.S. Environmental
Protection Agency, U.S. Fish and Wildlife Service, and U.S. De-
partment of Agriculture Soil Conservation Service. Washington, DC.
4. U.S. Army Corps of Engineers. 1987. Corps of Engineers wet-
lands delineation manual. Technical report Y-87-1. Vicksburg,
MS: Waterways Experiment Station.
5. U.S. EPA. 1994. Ground Water and Wellhead Protection.
EPA/625/R-94/001.
6. U.S. EPA. 1993. Technical manual for solid waste disposal facility
Criteria: 40 CFR Part 258. EPA/530/R-93/017 (NTIS PB94-
100450). Washington, DC.
7. U.S. EPA. 1991. Description and sampling of contaminated soils:
A field pocket guide. EPA/625/2-91/002.
8. U.S. EPA. 1985. Criteria for selecting a site for the land disposal
of hazardous wastes. EPA/600/2-85/018.
9. U.S. EPA. 1979. Process design manual for sludge treatment and
disposal. EPA/625/1-79/011, Cincinnati, OH.
10. U.S. EPA. 1977a. Process design manual for land treatment of
municipal wastewater. EPA/625/1-77/008. Cincinnati, OH (Octo-
ber), pp. C-13 toC-19.
11. U.S. EPA. 1977b. Database for standards/regulations develop-
ment for land disposal of flue gas cleaning sludges. EPA/600/7-
77/118. Cincinnati, OH. pp. 146-148.
12. U.S. EPA. 1972. Sanitary landfill design and operation. Report
No. SW65ts. Washington, DC. p.17
56
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Chapter 5
Public Participation Programs
5.1 Introduction
Public participation is very important to the success of
sludge use or disposal projects. A community's willing-
ness to cooperate with a project depends on:
• Its perceptions of the need for, costs of, and benefits
of the project.
• The degree to which the community feels it has been
kept honestly informed and has had a chance to
express its concerns and have its ideas incorporated
into the planning and operation.
The purpose of a public participation program (PPP) in
surface disposal is to inform and involve the public. Plan-
ning for public participation in a surface disposal project
involves careful and early evaluation of what should be
communicated, to whom, by whom, and when. This chap-
ter summarizes the major considerations involved in im-
plementing a successful program, including the objectives
and value of a public participation program, PPP partici-
pants, the design and timing of a program, and areas of
public concern in surface disposal.
5.2 Objectives
The objectives of a public participation program are:
• Promoting full and accurate public understanding of
the need for surface disposal, the active sewage
sludge unit selected, and the advantages and disad-
vantages of the project.
• Keeping the public well-informed on the status of
various planning, design, and operation activities.
• Soliciting from concerned citizens their relevant opin-
ions, perceptions, and suggestions involving surface
disposal.
The key to achieving these objectives is continuous
two-way communication between surface disposal site
planners/designers/qperators and the public. A
common problem for public officials is the assumption
that educational, informational, and other one-way com-
munication techniques provide for an adequate dia-
logue. When designing a public participation program,
sufficient mechanisms must be provided for meaningful
public input into the decision process (see Section 5.5).
A PPP will increase the lead time required to select,
design, and construct a surface disposal site. This
must be considered when initially determining the
need for a new site.
5.3 Value of a PPP
Public participation has become virtually essential to the
success of surface disposal projects. Public resistance
to a project, due either to legitimate concerns that are
not addressed or to misperceptions or anger resulting
from lack of involvement, generally will either make the
project impossible or at least more costly and difficult.
The process of involving the public does require some
investment of cost and time, but this likely will be far less
than the potential expense and delays risked by not
involving the public. A PPP is well worth the extra cost
as more expensive project delays are probable if an irate
populace becomes involved late in the process. The PPP
process contributes to an effective decision-making proc-
ess. The advantages of a PPP include (Canter, 1977):
• An increased likelihood of public approval or accep-
tance for the final plans.
• A method of providing useful information to decision-
makers, especially where values or factors that are
not easily quantified are concerned.
• Assurance that all issues are fully and carefully con-
sidered.
• A safety valve in providing a forum whereby sup-
pressed feelings can be aired.
• Increased accountability by decision-makers.
• An effective mechanism to encourage decision-mak-
ers to be responsive to issues beyond those of the
immediate project.
5.4 PPP Participants
5.4.1 Public Participants
The success of a public participation program depends,
in part, on who is involved. Failure to involve the
appropriate people at the appropriate times can result in
57
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unnecessary additional costs or time delays by increas-
ing public concern and inciting public anger. Therefore,
PPP design requires an effective publicity campaign
that will reach the appropriate people at the propertlmes
throughout the planning process. Special efforts should
be made to involve groups and individuals who:
• Have demonstrated an interest in environmental affairs.
• Are likely to be directly affected by the proposed
surface disposal project.
Table 5-1 lists the types of groups and individuals who
should be contacted regarding a public participation
program. A list of names and addresses of interested
persons and organizations in these categories for formal
and informal notifications and contacts should be devel-
oped at the beginning of a project. Identifying specific
groups and individuals as targets for public involvement
efforts helps to focus time and money on the most likely
participants, to focus the objectives of the PPP, and to
interpret how well the various involvement mechanisms
are working.
In addition, a special effort should be made to ensure
that the particularly important people, (such as influential
Table 5-1. Potential PPP Participants
The following groups and individuals should be contacted as part
of any PPP:
• Local elected officials
• State and local government agencies, including planning
commissions, councils of government, and individual agencies
• State and local public works personnel
• Conservation/environmental groups
• Business and industrial groups, including Chambers of
Commerce and selected trade and industial associations
• Property owners and users of proposed sites and neighboring
areas
• Service clubs and civic organizations, including the League of
Women Voters, etc.
• Media, Including newspapers, radio, television, etc.
The following groups can also be contacted, where appropriate:
• State elected officials
• Federal agencies
* Farm organizations
• Educational institutions, including universities, high schools, and
vocational schools
• Professional groups and organizations
• Other groups and organizations, possibly including various
urban groups, economic opportunity groups, political clubs and
associations, etc.
« Labor Unions
• Key Individuals who do not yet express their preferences
through, or participate in, any groups or organizations
individuals, people who are most likely to have strong
feelings about the site, and the media) are not only
informed, but convinced of the validity of the surface
disposal project. It is crucial that as many of these key
groups as possible support the surface disposal project
and speak out in favor of it during the public participation
program. Also, it is important that key participants get
involved as early as possible, to avoid situations where
previously disinterested individuals develop strong feel-
ings about the project when decisions have already
been made.
Local officials should be notified about the project before
the issue enters the field of public debate. This allows
them to form a more objective opinion about the project
and prepares them for inquiries from the public.
5.4.2 Program Staff
The success of a public participation program also hinges,
in part, on the attitudes, abilities, and experience of the
program staff responsible for communicating with the
public, either through preparation of informational mate-
rials or in live dialogue. One of the most important factors
in any PPP is the ability to establish the public's trust. A
PPP that fails to establish the public's trust may do more
damage than no PPP at all. Trust is the basis on which
program staff and participants can have a meaningful
and constructive dialogue on the project and associated
concerns. Without trust, the public may well maintain an
attitude of hostility and resistance. To establish trust, the
PPP staff, either individually or collectively will need to
have good technical understanding of the project and
good communication skills. Some abilities and attitudes
that help to build trust include (U.S. EPA, 1988):
• Involving all parties that may have an interest or stake
in the outcome.
• Involving the public before decisions have been made.
• Truly listening to the public's concerns and feelings
about the project. Being a good listener involves rec-
ognizing and respecting people's feelings, demon-
strating that you have heard and understood what
people have said, recognizing "hidden agendas" and
symbolic meanings (for example, property owners
near a surface disposal site may sound alarms about
ground-water pollution when their major concern is
actually property value depreciation), and adopting a
truly accepting, compassionate, and nonjudgmental
attitude toward the speaker.
• Respecting the public's concerns, even if these con-
cerns have no scientific basis.
• Be the first source of information and maintain the
trust of the media. Tell the good news and the bad,
and how the project will minimize the bad.
58
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• Being honest, frank, and open. This includes admit-
ting when you,are uncertain, do not know, or have
made a mistake, and getting back to people with
answers. It also involves disclosing information as
soon as possible. Any potential problem that is not
publicly addressed at the outset of a project will likely
be brought to the attention of the media, resulting in
the possible reduction of public support and the loss
of the project leadership's credibility.
• Communicating in nonscientific language that the
public can readily understand.
5.5 Design of a PPP
The PPP should be tailored to each particular situation
in terms of cost and scale. A certain minimum effort
should be put into every participation program but, within
a basic framework, appropriateness and flexibility are
the keys. A common sense approach in determining the
number and frequency of public involvement mecha-
nisms is recommended. When budget or time restric-
tions prohibit development of an ideal program, it is
more important to apply participation techniques that are
highly effective. Table 5-2 indicates the relative effective-
ness of the PPP activities suggested in this section.
Public participation is critical at various stages of the sur-
face disposal site development process. Most involvement
Table 5-2. Relative Effectiveness of Public Participation Activities
should come at the beginning of the planning process
when public input has the greatest potential to shape the
final plan. This early involvement helps determine the
limits to public and political acceptability of the project.
During this phase, the public plays a constructive, as
opposed to a reactive, role in decision-making. This
section discusses the critical planning stages where public
input is particularly important and the appropriate public
participation mechanisms at each stage.
5.5.1 Initial Planning Stage
During the initial planning stage, the scope and scale of
the entire PPP should be established, and the organiza-
tion of PPP components and the use of PPP mecha-
nisms should be determined. There are two general
types of PPP mechanisms:
• Educational/informational activities that represent one-
way communication from officials to the public.
• Interaction techniques that promote two-way commu-
nication.
The major activities during the initial planning stage are
mostly informational/educational. The officials doing the
communicating at this point may be operating authori-
ties, elected officials, engineering consultants, or even
public relations firms. These officials should inform the
public about the: •'.'.'.-
Communication characteristics
Public participation technique
Publ Ic hearings
Publ Ic meetings
Advisory Committee meetings
Hall ings
Contact persons
Newspaper articles
News releases
Audio-visual presentations
Newspaper advertisements
Posters, brochures, displays
Workshops
Radio talk shows
Tours/field trips
Onbud sm an
Task force
Telephone line
Level of
publ ic
contact
achieved
H
H
. L
M
L
H
M
M
H
H
L
It
L
L
L
11
Ability to
handle Degree of
specific two-way
interest communication
L
L
H
H
M
L
L
L
L
L
II
M
H
H
H
M
L
M
H
L
II
L
U
L
I
. L
M
M
H
H
H
M
I » low value
M » medium value
H » high value
59
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• Purpose of the surface disposal project.
• Rationale for selecting surface disposal over alterna-
tive use or disposal practices such as incineration
and land application.
• Need for the project in the community.
• General design and operation principles.
• Projected final land use.
• Potential for creation of new jobs, etc.
The public information products will likely also need to
include basic information explaining what sludge is, how
it is generated, and how it relates to the public demand
for clean water.
As initial site investigations get underway, two-way pub-
lic involvement activities become important. The follow-
ing mechanisms should be organized during this stage
(CH2M Hill, Donahue and Associates, et al., 1977):
• Public officials workshop. The purpose of this
workshop is to acquaint the concerned officials with
the technical considerations relevant to the surface
disposal project and to obtain input from local officials
on appropriate timing of activities and areas of po-
tential public concern.
• Advisory Committee. The role of this group is to
help organize citizen support for the proposed plan,
to act as a sounding board in providing citizen reac-
tions to various proposals, and to take an active part
in decision-making. The group should include repre-
sentatives of local government departments, commu-
nity organizations, private industry, and others.
Consultant progress reports can be presented during
these meetings and later publicized.
• Mailing list. Comprehensive mailing lists are the
foundation of an information output program. To be
effective, they must represent a broad cross-section
of groups and individuals and be frequently expanded
and updated.
• Liaison/contact persons. Liaison/contact persons
are responsible for receiving input, answering ques-
tions, expanding mailing lists, and generally being re-
sponsive. They keep logs of all questions and refer
issues of general concern to the appropriate people for
consideration. These positions should be held by per-
sons who are actively involved in the surface disposal
decision-making process; e.g., a consulting engineer,
public works official, or other comparably informed in-
dividuals. In large municipalities it may be advanta-
geous to hire an individual to handle public relations.
• Media program. This involves organizing an effec-
tive publicity campaign using various media. The me-
dia should be contacted as early as possible and
every effort should be made to convince them of both
the need for and effectiveness of a surface disposal
project before the topic becomes an emotional issue.
In this way, objective treatment of the issue by the
media is more likely. Again, the extent of this program
depends upon the particular situation. Various chan-
nels include:
- Newspapers. A series of informative articles on
surface disposal can be timed to appear through-
out the project to sustain public interest and serve
as an educational tool. Each article or news re-
lease can also transmit hard news such as notices
of public meetings, or articles describing events at
public meetings.
— Television. This method can be very expensive, but
can also be very useful in transmitting information.
Through careful planning, some free coverage of
the project can probably be arranged through news
programs, public service announcements, or sta-
tion editorials.
- Advertisements. Full-page newspaper advertise-
ments could be used to relate complex information.
They can incorporate a mailback feature to high-
light citizen concerns, and solicit participation of
interested individuals.
- Posters, brochures, or displays. These can be
highly effective educational tools, especially when
particularly creative and put in high traffic areas or
given wide distribution.
- Radio advertisements or informational talks. The
radio can be used to advertise events or information
in much the same way that newspapers are used.
• Classroom educational materials. This can be an
effective way of educating school children and their
parents. Presentations can be made in individual
schools or, more economically, special newsletters
and brochures can be designed for use in schools
' and distribution to other audiences.
5.5.2 Site Selection Stage
The major activities of the initial planning stage are
preparatory mechanisms for the site selection stage.
Site selection generally involves a preliminary screening
of numerous potential sites after which several sites are
selected for more detailed investigation. These selected
sites should be subjected to intense public scrutiny. It is
at this point that public participation can play a particu-
larly formative role in determining the final site, design
and operation procedures, etc.
Most public interest and involvement—including the most
vocal and organized protests—occur during the site
selection stage. Therefore, the major thrust of the PPP
should come during this stage, with a particular empha-
sis on two-way communication including:
60
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• Public meetings. These are an excellent mechanism
for providing public information, receiving input, and
achieving one-to-one contact between consultants,
local officials, and the public. They are normally less
structured than public hearings and therefore, more
likely to result in dialogue. Generally, a series of such
meetings is held in different locations within the plan-
ning area to provide maximum opportunity for atten-
dance by the public. These are a good arena for the
use of audiovisual presentations. These meetings
work especially well when there are concrete issues
to be discussed, and should be timed to coincide with
particularly critical periods in the decision-making
process. For example, the public at these meetings
could screen the site selection criteria or even rate
the candidate sites against those selected criteria.
The more successful meetings are usually a result of
heavy advance work. Overcoming public apathy can
be difficult, but is critically important in these early
planning stages. Consultant contracts should clearly
.specify the number of public meetings to be held
because it is often costly and time-consuming to pre-
pare for them.
• Workshops. Generally, these have positive results
although they are not widely used because of low
turnout. Such groups usually involve citizens being
given courses of instruction by agency staff, and then
addressing specific work efforts on the basis of such
instruction. Basically workshops are an educational
tool with interaction features.
• Radio talk-shows. Many communities have local ra-
dio talk shows where residents can call in and voice
their opinions. The consultant and/or a local official
could give a short presentation on the surface dis-
posal plan and then field callers' questions. This is a
good opportunity to dispel some misinformation, but
views of the callers do not necessarily represent
those of the general public.
5.5.3 Selected Site and Design Stage
In this stage, the surface disposal site is selected and
detailed site design begins. Generally, the number of
participants involved may drop off in this stage, but the
level of activity may substantially increase. No matter
how active the public has been up to this point, nearby
residents of the site are not going to be happy with the
siting decision. Participation efforts should increase on
this particular group. Giving these people a role in site
design will alleviate some hostility and, in the long-run,
improve the public's opinion of the proposed operation.
Appropriate activities in this stage are:
• Tours/field trips. These are useful activities for spe-
cial interest groups, such as residents near the se-
lected surface disposal site, and the press. Before
the proposed surface disposal site is designed and
permitted, a tour of a comparable existing and opera-
tional surface disposal site should be made. This can
be far more effective than countless abstract discus-
sions. After the proposed surface disposal site is
opened, tours can be offered of this site to educa-
tional and other groups. Arranging for aerial views of
proposed and existing sites for small groups by char-
tering a plane can be especially effective.
• Audiovisual presentations. These can be quite
useful at public information meetings to reach people
missed by the field trips. The effectiveness of this tool
depends on the quality of the script and visuals, but
audiovisual presentations can dispel much of the mis-
information about surface disposal that, may result
from past experience with improperly run sites.
• Task forces. The purpose of these groups is to rec-
ommend design procedures in areas of particular
concern for the public. This group could be a sub-
group of the Advisory Committee or a committee
made up of residents near the site. To be most effec- .
tive, the group should represent the various interest
groups and have a technical orientation.
• Formal public hearings. Although at least one is
usually required by law, a public hearing is usually
only a formality. Public hearings tend to be structured
procedures involving prior notification, placement of
materials in depositories for citizen review prior to the
hearing, and a formal hearing agenda. The hearing
itself usually takes the form of a presentation by the
consultants, followed by statements from the citizens
in attendance. Questions are normally allowed, but
argumentative discussion and "debates" are discour-
aged because of time limitations. Sponsors tend to
prefer to adopt a "listening" posture and allow the
public to express itself without challenge. This kind
of detached attitude tends to generate a great deal
of hostility in the public. It conveys the message that
the public is powerless to change engineering deci-
sions and this is precisely the type of message that
a PPP is supposed to dissipate. Because public hear-
ings are usually held late in the site development
process after the design is already completed, they
provide an insufficient means of legitimate citizen in-
volvement in the complete planning, design, and op-
eration decision-making process. The responsiveness
of a public hearing can be enhanced by having elected
officials chairing or at least participating in the process.
Nevertheless, public hearings perform their proper legal
and review functions only as part of a total PPP.
5.5.4 Construction and Operation Stage
The role of the public in this stage is limited, but the
actions of engineers and surface disposal site operators
are extremely important. It is in this stage that the site
61
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developers must "make good" on their assurances of
running a well-operated, well-maintained site. Public
confidence in local officials can be reinforced through
the proper handling of surface disposal site develop-
ment. Otherwise, it will be extremely difficult to establish
public support for this or any future surface disposal
project Public participation must continue throughout
the project—if some minimum level is not maintained
even the current project may fail.
Public involvement during the construction and opera-
tion stage most likely will consist mainly of complaints
related to construction and operation activities. Mecha-
nisms to handle this interaction include:
• Telephone line. This is a good tool to register com-
plaints and concerns and to answer questions. It is im-
portant that each call be followed up with a response
addressing the actions taken to alleviate the problem.
• Ombudsman or representative. This is an individ-
ual who has the ear of the site operators and can
, mediate any difficulties that citizens feel are not being
adequately handled.
5.6 Timing of Public Participation
Activities
A public participation program should begin very early in
the development of a proposed project and continue
throughout the project. All persons concerned should
have the opportunity to express their views before any
decisions affecting the general public are made and
should be kept informed and involved throughout the
course of the project.
To be effective, program activities must be diversified
and sustained. Correct timing is critical. Table 5-3 lists
suggested timing of PPP activities for a sample surface
disposal site project. Public hearings are formalities and,
as such, may occur only at the beginning and end of the
planning process. Advisory Committee meetings have
the function of providing a forum for progress reports
and regular input and, therefore, are scheduled to occur
from every 2 to 3 months. Public meetings are held
jointly with Advisory Committee meetings and are timed
to obtain input during the critical points in decision-mak-
ing. Sufficient time is allowed after each public meeting
to give decision-makers time to react to comments and
incorporate suggestions before final determinations are
made. The various other informational/educational ac-
tivities are scheduled around the public and Advisory
Committee meetings to arouse public interest at times
when input will be the most valuable.
5.7 Potential Areas of Public Concern
A PPP should dispel any myths and misinformation
the public may have concerning surface disposal—for
example, the widely held perception that sludge is al-
ways malodorous, highly contaminated, and otherwise
repulsive. A PPP also should address the impacts of all
surface disposal developments and other issues of con-
cern in an environmental impact report, if one has been
prepared. The most effective participation activities for
handling these issues are the interaction techniques
(i.e., public meetings, tours/field trips, and displays that
are manned by personnel to answer questions). Some
of the concerns most likely to arise during surface dis-
posal development are:
• Loss of prior land use
• Land planning and zoning problems
• Ground-water pollution and leachate
• Methane gas migration
• Vector attraction
• Noise
• Odor
• Aesthetics, including site visibility
• Safety and health
• Traffic
• Spillage
• Sedimentation and erosion
• Completed site and final land use
Local officials should be prepared to handle questions
concerning these issues. Obviously most of these prob-
lems simply do not arise with a well-operated, efficiently
run site, and this fact should be heavily emphasized.
Also, because each situation is unique, mechanisms to
ease these concerns have to be tailored to the charac-
teristics of each site. Local residents and officials should
be creative in solving any problems that may arise.
Above all, the attitude of local officials during interac-
tions with citizens is extremely important and must at all
times be open and responsive.
5.8 Conclusion
Even the best program to involve the public in surface
disposal site decision-making may not alleviate citizen
dissatisfaction or anger. This criticism has often been
cited to justify only minimal public participation efforts.
However, active public involvement will positively con-
tribute to the long-term political and public acceptability
of any plan, increase public confidence in local officials,
and give citizens a real opportunity to take part in the
land management decisions of their community. A PPP
is an essential part of any surface disposal program.
62
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Table 5-3. Suggested Timing of Public Participation Activities for Sample 30-Month Landfill Project
PPP activities and mechanisms
Publ ic hearings
Publ Ic meetings
Advisory Committee meetings
HalHng list development and
mall Ings
Availability of contact people
Newspaper articles
New releases
kudfo-vlsual presentations
Newspaper advertisements
'osters, brochures, and
displays
Workshops
Radio talk-shows
Tours/field trips
Ombudsman
Task force
Telephone line
Decision stage
Initial
planning
Site selection
Design
Con- I
structlonj Operation
Month
2
X
4
©
®
X
X
X
X
X
X
X
10
X
X
12
(x)
(x)
X
4
X
X
16
•
X
X
X
X
X
la
$
Cd
X
20
X
X
22
X
X
X
24
X
26
X
28
X
30
®
X
X
2
4
X
joint meeting
5.9 References
1. Canter, L. 1977. Environmental impact assessment. New York, NY:
McGraw-Hill, pp. 221-222.
2. CH2M Hill,,Donahue and Associates, etal. 1977. Preliminary draft:
Community involvement program, metropolitan sewerage district
of the county of Milwaukee, water pollution abatement program
(December), pp. A-1 to A-8.
3. U.S. EPA. 1988. Seven cardinal rules of risk communication. OPA-
87-020. Washington, DC.
63
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Chapter 6
Field Investigations
6.1 Purpose and Scope
This chapter summarizes the regulatory requirements
that might require site-specific field investigations for
selecting a site for surface disposal of sludge, and it
provides an overview of methods and approaches to
planning for field investigations. Because the extent of
field investigations for a particular site will depend on the
size and complexity of surface and subsurface condi-
tions, this chapter emphasizes relatively simple and
inexpensive field techniques that in many instances
might be adequate for sludge surface disposal sites for
small and medium-sized communities (i.e., tens of
acres). Small-scale sites with complex subsurface con-
ditions and sites for surface disposal of sewage sludge
produced by large cities (i.e., hundreds of acres) will
require use of more sophisticated and expensive field
equipment and methods. This chapter also identifies
reference sources where more detailed information on
such methods can be found.
6.2 Regulatory Requirements
6.2.1 Part 503 Regulation
Section 4.2.1 (Site Selection Regulatory Requirements)
describes in more detail the Part 503 requirements con-
cerning field investigations and the siting of sewage
sludge surface disposal sites. If the site selection proc-
ess described in Chapter 4 identifies one or more poten-
tially suitable sites for which Part 503 locational
restrictions might apply, one or more of the following
types of field investigations might be required:
• A determination about the presence of any threat-
ened or endangered species or a critical habitat.
• Hydrologic engineering studies to determine whether
active sewage sludge units can be designed so as
not to restrict flow of a 100-year flood, where the
proposed active sewage sludge unit is located within
the boundaries of a 100-year floodplain.
• Geologic, geophysical, and soil engineering investi-
gations where the active sewage sludge unit is lo-
cated within a seismic impact zone or in the vicinity of
one or more active faults (i.e., movement has occurred
within the last 11,000 years or so), or the area com-
prises geologically unstable materials.
• Geologic and geotechnical investigations (generally
required when the active sewage sludge unit will
have a liner and leachate collection system).
• Soil and hydrologic investigations, if known or sus-.
pected wetlands are located within the proposed sur-
face disposal site.
6.2.2 Part 258 Regulations
A complete discussion of the regulatory requirements
under Part 258 concerning field investigations and siting
of MSW landfills is beyond the scope of this manual. See
U.S. EPA (1993d) for detailed information on the Part
258 regulation.
6.2.3 Other Regulatory Requirements and
Programs
Special or more focused field investigations also might
be required if use of the site for sewage sludge disposal
is restricted by other regulatory requirements of pro-
grams at the federal, state, or local level. Examples of
siting issues covered by other federal statutes or regu-
latory programs include:
• Presence of sites of archaeological or historical signifi-
cance. Significant archaeological sites are often located
within floodplains or on terraces along major rivers.
• Areas protected under the EPA-approved state well-
head protection programs or under EPA's sole source
aquifer program.
• Areas located over aquifers with a Class I or Class II
designation.
Any state environmental protection statutes and regula-
tions not originating at the federal level that might affect
siting of sewage sludge surface disposal sites should be
identified during the site selection process and appropri-
ate field investigations should be undertaken. Similarly,
any local zoning ordinances or restrictions should be
identified in the site selection phase, and field investiga-
tions should be designed to obtain any information required
65
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to demonstrate compliance or justify the granting of
variances.
6.3 Collection of General Site
Information
Collection and review of available information about a
site and the surrounding area should be the starting
point for any field investigation. If multiple potential sites
have been evaluated during the site selection process
(Chapter 4) then much of the more general types of
information for the area (i.e., soil, geologic, and hydro-
logic maps and reports) will have already been gath-
ered. Such maps are useful for providing a general
understanding of the geologic and hydrologic setting for
a particular site, but generally will not provide specific
information about the site itself. Table 6-1 identifies gen-
eral sources for identifying and reviewing existing infor-
mation. Makower (1992) is a useful general reference
on types and sources of maps. This section discusses how
to obtain more specific types of information: (1) topog-
raphy and aerial photographs (Section 6.3.1); (2) soils,
geologic, and related information (Section 6.3.2); and
(3) hydrologic and related information (Section 6.3.3).
Major types of commonly available information that1 can
provide useful information for sites involving tens or
hundreds of acres include: (1) topographic maps (scale
1:24,000), (2) aerial photographs (scale 1:15,000 to
1:20,000 are best), (3) published Soil Conservation
Service (SOS) soil survey maps (which usually range in
scale from around 1:15,000 to 1:20,000), (4) water well
drill logs, and (5) Federal Emergency Management
Agency (FEMA) floodplain maps. Speaking with knowl-
edgeable individuals in local government utility and
planning agencies, state natural resource/environ-
mental agencies, and district offices of the SCS, U.S.
Army Corps of Engineers, U.S. Geological Survey
(USGS), and U.S. Fish and Wildlife Service is probably
the best way to identify existing published and unpub-
lished maps and reports with detailed information about
the site or nearby areas. Interviews with local, long-time
residents also are an important source of information
about the use-history of a site.
In most instances the most important available informa-
tion relevant to a site can be identified after 2 or 3 days
spent contacting agencies on the telephone. It also
might be necessary to spend some time in one or more
libraries (Table 6-1) reviewing documents that are no
longer in print. For large projects, on-line computer
searches can save significant time and money by
quickly retrieving article citations on a given subject and
eliminating manual searches of annual or cumulative
indexes. A search is performed using key words, author
names, or title words, and can be delimited by ranges
of dates or a given number of the most recent or dated
references. A search typically requires about 15 minutes
online and costs $50 to $100 for computer time and
off-line printing of citations and abstracts. Doctoral dis-
sertations and masters theses are another possible
source of information about an area. Table 6-1 provides
information on how to identify possibly relevant disser-
tations and theses, and how to obtain them.
6.3.1 Topography and Aerial Photographs
Table 6-2 identifies sources for topographic maps. Topo-
graphic maps (at a scale of 1:24,000) published by the
USGS are available for most areas of the United States
and are available in electronic format from several sources
(Table 6-2). The resolution of these maps (which generally
have contour intervals of 10 ft or more) are usually not
adequate for detailed site engineering and design pur-
poses (see Section 6.4.1), but are useful for identifying
significant site surface characteristics during initial field
investigations. The simplest method for identifying the
availability and titles of topographic maps is to refer to
a current state index map, which shows all currently
available topographic maps. If a potential site is located
near a city, more detailed topographic maps may be
available from city planning or utility departments.
The first place to check for available aerial photographs
is the nearest district offices of the SCS and the Agricul-
tural Stabilization and Conservation Service. These of-
fices, usually located in the same building and serving
one or more counties, should have on file all aerial
photographs taken for the U.S. Department of Agricul-
ture throughout the county; these will typically range in
scale from 1:15,000 to 1:24,000 (1 in. = 1,250 ft to 1 in.
= 2,000 ft). In parts of the United States, the earliest
aerial photographs date back to the 1930s. Examination
of the full time-series of aerial photographs for a site is
an excellent way to learn about changes in vegetation
and land use that have taken place. Fracture trace and
lineament analysis using aerial photographs is a useful
way to identify possible preferential paths of contami-
nant transport. Again, all available aerial photographs
should be viewed stereoscopically to identify fracture
traces and other lineaments, because the same line-
aments might not be visible on all photographs due to
differences in vegetation or atmospheric conditions at
the time the photograph was taken.
For site-specific investigations, aerial photographs with
a scale larger than 1:40,000 have a relatively limited
usefulness; however, larger-scale photographs (up to
1:120,000), including satellite remote sensing imagery
might be useful for placing a site in its broader environ-
mental context. Table 6-3 identifies sources for larger-
scale aerial photographs and satellite remote sensing
imagery. Landsat satellite sensors record images in four
spectral bands: Band 4 emphasizes sediment-laden and
shallow waters; Band 5 emphasizes cultural features;
Band 6 emphasizes vegetation, land/water boundaries,
66
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Table 6-1. General Information Sources (U.S. EPA, 1993e; Sara, 1994)
Source Type(s) of Information Comments
Federal agencies
State, regional, and local
agencies
Knowledgeable individuals
State and federal projects
AGI Directory of Geoscience .
Departments
National Technical Information
Service, 5228 Port Royal Rd.,
Springfield, VA 22161;
800/553-6847
Libraries
Government Agency
Academic Institutions
Local public libraries
All types of information (see
subsequent tables).
Soils, land use, flood plains,Aground
water, aerial photographs, well
records, geophysical borehole logs.
Historic information, past site owners
and practices. Published and
unpublished reports and maps.
Site specific assessment data for
dams, harbors, river basin
impoundments, and federal highways.
Faculty members.
Government and other technical
publications that are out of print or
for which limited copies were printed.
All types.
All types.
Physical and historical characteristics
of the surrounding area.
Computerized Online Databases
DIALOG subscriptions and
information: 800/3-DIALOG
Master Directory (MD), User
Support Office, Hughes STX
Corp., 7601 OraGlen Dr., Suite
300, Greenbelt, MD 20771;
301/513-1687
Earth Science Data Directory
(ESDD), U.S. Geological
Survey, 801 National Center,
Reston, VA 22092;
703/648-7112
Accesses over 425 data bases from
a broad scope of disciplines
including such databases as
GEOREF and GEOARCHIVE.
The MD is a multidisciplinary
database that covers earth science
(geology, oceanography, atmospheric
science) and space sciences.
ESDD is a database that contains
information related to geologic,
hydrologic, cartographic, and
biological sciences.
See subsequent tables.
Local county, town, and city planning boards commonly
provide data on general physical characteristics of areas within
their jurisdiction. Most states have environmental protection
and natural resource agencies (geology, water, agriculture,
etc.) that have information related to geology, remote sensing,
and water.
Time can be saved in the initial stages of a data search by
contacting knowledgeable individuals personally or by
telephone for references and an overview of an area, as well
as for specific problems and details that may be unpublished.
People to contact include: federal agency personnel (USGS,
SCS, Army Corps of Engineers, Fish and Wildlife Service);
state environmental protection, geological and water survey
personnel; local well drillers, consulting engineers, architects,
and residents.
Project reports contain data on soil, hydrologic, geologic and
geotechnical characteristics as well as analysis, construction
drawings and references. Most are easily obtained by
contacting the responsible agency. Surface water and
geological foundation conditions such as fracture orientation,
permeability, faulting, rippabillty, and weathered profiles are
particularly well covered in these investigations.
Regular updates of faculty, specialties, and telephone numbers.
Documents can be obtained as hard copy of microfiche.
Excellent library facilities are available at the U.S. Geological
Survey offices in Reston, VA; Denver, CO; and Menlo Park,
CA. U.S. EPA has excellent libraries in Washington, its 10
Regional Offices, and environmental research laboratories
(Cincinnati, OH; Athens, GA; Ada, OK; Las Vegas, NV). State
environmental and natural resource agencies often have
libraries addressing the Agency's main focus.
The amount of environmental information that can be obtained
from academic institutions varies with the size. Larger
universities often have separate geology libraries and serve as
repositories for federal documents.
Especially good sources for local maps and history. Almost any
other document can also be obtained through interlibrary loan.
Provides indexes to book reviews and biographies; directories
of companies, people, and associations; and access to the
complete text of articles from many newspapers, journals and
other sources.
MD is a free online data information sen/ice for data generated
by NASA, NOAA, USGS, DOE, EPA, and other agencies and
universities as well as international data bases. Includes
personal contact information, access procedures to other
databases. Contact MD User Support Office for information on
access via span nodes, Internet, or direct dial.
Also included are databases that reference geographic,
sociologic, economic, and demographic information.
Information comes from NOAA, NSF, NASA; EPA and
worldwide data sources.
67
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Table 6-1. General Information Sources (U.S. EPA, 1993e; Sara, 1994} (continued)
Source Type(s) of Information Comments
Dissertations and Theses
Comprehensive Dissertation
Index (GDI)
DATRIX II, University
Microfilms International,
300 N. Zeeb Rd.,
Ann Arbor, Ml 48106;
800/521-3042,
313/761-4700 (In Alaska,
Hawaii, and Michigan)
United States Geology: A
Dissertation Bibliography by
Stata
Dissertation Abstracts
International, Volume B -
Science and Engineering and
Masters Abstracts
PhD doctoral dissertations.
PhD dissertations and masters
theses.
PhD dissertations and masters
theses.
Extended abstracts of PhD
dissertations from more than 400
U.S. and Canadian universities;
150-word abstracts of masters theses.
Citations began in 1861 and include all doctoral dissertations
from U.S. universities and most accepted in North America
thereafter. The index is available at larger library reference
desks and is organized in 32 subject volumes and 5 author
volumes. Specific titles are located through title keywords or
author names.
Using title keywords, a bibliography of relevant theses can be
compiled and mailed to the user within one week. In addition,
the DATRIX Alert system can automatically provide new
bibliographic citations as they become available.
Free index from University Microfilms International (UMI).
However, this index does not include dissertations from some
universities that do not make submissions to UMI for
reproduction or abstracting. DATRIX II or Comprehensive
Dissertation Index must be used to locate such citations.
Monthly publication of UMI. Abstracts of potentially useful titles
obtained from GDI or DATRIX II can be scanned to determine
whether it is relevant to the project at hand. Both Dissertation
Abstracts International and Masters Abstracts are available at
many university libraries. A hard (paper) or microfilm/fiche copy
on any abstracted dissertation can be purchased from UMI.
Non-indexed or abstracted dissertations or theses must be
obtained from the author or the university where the research
was completed.
Tablo 6-2. Topographic Data Sources (U.S. EPA, 1993c; Sara, 1994)
Source TVpe(s) of Information
Comments
Branch of Distribution, USGS
Map Sales, Box 25286.
Federal Center, Denver, CO
80225; 303/236-7477.
Geographic Names
Information System (GNIS),
USGS. 523 National Center,
Reston, VA 22092;
703/648-4544
Geographic Information
Retrieval and Analysis System
(GIRAS), USGS. Earth
Science Information Center
(ESIC), 507 National Center,
Reston, VA 22092;
800/USA-MAPS
U.S. Geodata Tapes,
Department of the Interior,
Room 2650, 18th & C Sts.,
NW, Washington, DC 20240;
202/208-4047
Index and quadrangle maps for the
eastern U.S. and for states west of
the Mississippi River including Alaska
and Hawaii.
Topographic Names Database:
descriptive information and official
names for about 55,000 topographic
maps, including out-of-print maps.
Topographic Maps Users Service:
organized and summarized
information about cultural or physical
geographic entities.
Land use maps, land cover maps,
and associated overlays for the
United States.
These computer tapes contain
cartographic data available in two
forms: (1) graphic to generate
computer plotted maps; (2)
topologically structured for input into
geographic information systems.
A map should be ordered by name, series, and state. The
same quadrangle name may be used 'at several scales so it is
especially important that the series scale be specified: 7.5
minute (1:24,000), 15 minute (1:62,500), or two-degree
(1:250,000). Other scales may be available for particular areas.
GNIS provides a rapid means of organizing and summarizing
current information about cultural or physical geographic name
entities. The database contains a separate file for each state,
the District of Columbia, and territories containing all 7.5 min.
maps published or planned. Printouts and searches are
available on a cost recovery basis.
Map data are available in both graphic and digital form, and
statistics derived from the data are also available. Searches for
either locations or attributes can be made.
Tapes are available for the entire U.S., including Alaska and
Hawaii, and are sold in 4 thematic layers: boundaries,
transportation, hydrography, and U.S. Public Land Survey
System. Each can be purchased individually. Tapes can be
ordered through the Earth Science Information Center
(ESIC—see above) or through the following ESIC offices:
Anchorage, AK (907/786-7011); Denver, CO (303/236-7477);
Menlo Park, CA (415/329-4309); Reston, VA (703/860-6045);
Rolla, MO (314/341-0851); Salt Lake City, UT (801/524-5652);
Spokane, WA (509/456-2524); and Stennis Space Center, MS
(601/688-3541).
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Table 6-2. Topographic Data Sources (U.S. EPA, 1993c; Sara, 1994) (continued)
Source Type(s) of Information Comments
Topographic Database,
National Geophysical Data
Center, NOAA, Code E/GC1,
325 Broadway,
Boulder, CO 80303;
303/497-6764
State geological surveys
Commercial map supply
houses
This system contains a variety of
topography and terrain data sets
available for use in geoscience
applications.
Topographic maps.
Topographic and geologic maps.
The data were obtained from U.S. Government agencies,
academic institutions, and private industries. Data coverage is
regional to worldwide; data collection methods encompass
map digitization to satellite remote sensing.
Many state geological surveys sell USGS topographic maps
for the state in which they are located.
Commercial map supply houses often have full state
topographic inventories that may be out of print through
national distribution centers. Digitized topographic maps can
also be obtained from some suppliers.
Table 6-3. Aerial Photography and Remote Sensing Sources (U.S. EPA, 1993c; Sara, 1994)
Source Type(s) of Information Comments
Conventional aerial photography
scales of 1:15,000 to 1:40,000.
Aerial Photography Field
Office, U.S. Department of
Agriculture, P.O. Box 30010,
Salt Lake City, UT 84130;
801/975-3503
" District ASCS and SCS offices Aerial photography.
Earth Resources Observation
System (EROS) Data Center,
USGS, Sioux Falls, SD 57198;
605/594-6151
NASA Aerial Photography
Photogrammetry Division,
NOAA, 6001 Executive Blvd.,
Rockville, MD 20852;
301/443-8601
Aerial Photo Section, Bureau
of Land Management,
P.O. Box 25047,
Bldg. 46, Federal Center,
Denver, CO 80225;
303/236-7991
Cartographic and
Architectural Branch,
National Archives,
8 Pennsylvania Ave. NW,
Washington, DC 20408;
703/756-6700
Commercial Aerial
Photography Firms
Aerial photography (scales 1:20,000
to 1:60,OQO) obtained by USGS and
federal agencies other than SCS is
available as 230 mm by 230 mm
prints. Landsat satellite multispectral
imagery can also be obtained from
the EROS Data Center.
Aerial photography available in a
wide variety of formats (black and
white, color, color infrared). Scales
generally range from 1:60,000 to
1:120,000.
Color and black-and-white aerial
photographs at scales ranging from
1:20,000 to 1:60,000.
BLM has aerial photographic
coverage of over 50 percent of its
land in 11 western states.
Airphoto coverage from the late
1930s to the 1940s can be obtained
for portions of the U.S.
Existing air photos flown for other
clients, or new photography for site
of interest.
Aerial photographs by the various agencies of the U.S.
Department of Agriculture: Agricultural Stabilization and
Conservation Service (ASCS), Soil Conservation Service
(SCS), and Forest Service (USFS) cover much of the U.S.
District offices of the USDA Agricultural Stabilization and
Conservation Service and the Soil Conservation Service are
usually the best starting point for identifying available aerial
photography at the county level.
Because of the large number of individual photographs needed
to show a region, photomosaic indexes are used to identify
photographic coverage of a specific area. The EROS Data
Center has more than 50,000 such mosaics. Mosaics and
aerial photographs are also available from the USGS Map
Sales office in Denver (Table 6-2). The Data Center can
provide a computer listing of all imagery on file for (1) point
search (longitude and latitude), (2) area quadrilateral (four
lat/long coordinates), and (3) map specification (point or area).
Coverage restricted to areas selected for testing of
remote-sensing instruments and techniques. Available from
EROS Data Center (see above).
The Coastal Mapping Division of the National Oceanic and
Atmospheric Administration (NOAA) maintains coverage of the
tidal zone of the Atlantic, Gulf and Pacific Coasts. An index
can be obtained from the Coastal Mapping Division.
This service may be useful for early documentation of site
activities. Early airphotos may also be on file in ASCS and
SCS District offices (see above). Foreign airphoto coverage for
the World War II period is also available.
Many firms can also develop detailed topographic site maps
using photogrammetric techniques. For a listing of nearby firms
specializing in these services consult the yellow pages or
contact: American Society of Photogrammetry and Remote
Sensing, 5410 Grosvenor Lane, Suite 210, Bethesda, MD
20814; 301/493-0290.
69
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and landforms; and Band 7 is similar to Band 6 except
that it provides better penetration through haze. Band 5
gives the best general-purpose view of the earth's surface.
6.3.2 Soils, Geologic, Geophysical, and
Geotechnical Information
Table 6-4 identifies sources of information on soils, ge-
ology, geophysical and geotechnical information. If
available, a county soil survey published by the SCS is
one of the single best sources of .information about a site
because it also provides an indication of subsurface
geologic conditions and contains a wealth of information
on typical soil physical and chemical characteristics
(Table 6-5). If a soil survey is not available, check to see
if the site is located within a farm property listed with the
local Soil and Water Conservation District. If so, there
may be an unpublished farm survey on file in the District
SCS office. As with published topographic maps gener-
ally, the scale of an SCS soil survey is usually not
adequate for site engineering and design purposes;
thus, part of a field investigation should include more
detailed mapping of soils, if possible (see Section 6.4.2).
If an unpublished soil survey is available, SCS soil
series descriptions and interpretation sheets should be
obtained for all soil series that have been mapped in the
area. Table 6-5 summarizes the kind of information that
can be found on these sheets. Estimated soil properties
are typically given as ranges or values for different soil
horizons, and direct field observation and sampling is
required for more accurate definition of soil properties.
Even if a published soil survey is available, these sheets
provide a convenient reference for characteristics of soil
series occurring within a site. The same information on
Table 6-4. Soils, Geologic, Geophysical, and Geotechnical Data Sources (U.S. EPA, 1993c; Sara, 1994)
Source TVpe(s) of Information Comments
USDA Soil Conservation
Service; 202/720-1820
U.S. Geological Survey
(USGS) Bocks and Open File
Reports Sales, Federal Center,
Box 25425, Denver, CO
80225; 303/236-7476
USGS Main Library, 950
National Center, Reston, VA
22092; 703/648-4302
Geologic Names of the United
States (GEONAMES),
Geologic Division, USGS, 907
National Center, Reston, VA
22092
County-level soil surveys are available
for about 75% of the country. Soil series
descriptions and interpretation sheets
contain information on soil physical and
chemical properties.
USGS produces annually numerous
publications including maps, bulletins,
circulars, professional papers and
open-file reports.
The Reston library contains more than
800,000 books, monographs, serials,
maps and microforms covering all
aspects of earth and environmental
sciences.
GEONAMES is an annotated index of
the formal nomenclature of geologic
units of the U.S. Data includes
distribution, geologic age; USGS usage,
lithology, thickness, type locality and
references.
Geologic Indexes and Databases
A Guide to Information
Sources In Mining, Minerals,
and Geosciences (Kaplan,
1965)
Information on more than 1,000
governmental and nongovernmental
organizations in 142 countries.
A Subject and Regional
Bibliography of Publications
and Maps in the Geological
Sciences (Ward, 1972)
Bibliographies of geologic information for
each state in the U.S. and reference for
general maps and ground-water
information for many sites.
Bibliography and Index of Geology
American Geological Institute
(AGI)
Includes worldwide references with
listing by authors and subject. Published
monthly with annual cumulative index.
District offices covering one, or several counties may
contain unpublished soil mapping. Published soil surveys
and soil series description and interpretation sheets can be
obtained from SCS state offices, located in each state
capital.
USGS Circular 900, Guide to Obtaining USGS Information
(Dodd et al., 1989) is available at no cost.
USGS has one of the largest earth science libraries in the
world. Library staff and users can access the online catalog
from terminals at the Reston library and from the regional
libraries located in Denver, CO; Flagstaff, AZ; and Menlo
Park, CA. The database can be searched by author, title,
key words, subjects, call numbers, and corporate/
conference names.
Printouts are not available. Diskettes containing data for
two or more adjacent from USGS books and reports sales
(address above). Magnetic tapes can be obtained from
NTIS (Table 6-1).
An older, useful guide. Part II lists more than 600
worldwide publications and periodicals including indexing
and abstracting services, bibliographies, dictionaries,
handbooks, journals, source directories, and yearbooks in
most fields of geosciences.
Provides a useful starting place for many site assessments.
A general section outlines various bibliographies and
abstracting services, indexes and catalogs, and other
sources of geologic references.
Replaces separate indexes published by the USGS (North
American references only) and the Geological Society of
America/GSA (references exclusive of North America) until
1969. Both publications merged in 1970 and were
published by GSA through 1978, when AGI continued its
publication.
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Table 6-4. Soils, Geologic, Geophysical, and Geotechnical Data Sources (U.S. EPA, 1993c; Sara, 1994) (continued)
Source Type(s) of Information Comments '
GEOREF
American Geological Institute
GEODEX Retrieval System
with Matching Geotechnical
Abstracts
GEODEX International, Inc.,
P.O. Box 279, Sonoma, CA
95476
KWIC (Keyword-in-Cpntents)
Index pf Rock Mechanics
Literature
Geophysical Data
U.S. Geological Survey, Box
25046, Federal Center,
Denver, CO 80225
National Geophysical Data
Center (NGDC), NOAA, Mail
Code E/GC, 325 Broadway,
Boulder, CO 80303; Land
data: 303/497-6123; Seismic
data: 303/497-6472
Electric Well Log Services,
P.O. Box 3150, Midland, TX
•79702; 915/682-7773
Geophysical Survey Firms
Computer database with bibliographic
citations from 1961 to present.
Computer database with engineering
geological and geotechnical references.
Engineering geologic and geotechnical
references.
Aeromagnetic maps, magnetic
declination, landslide information,
earthquake data. Many USGS
publications contain geophysical survey
for specific areas.
NGDC maintains a computer database
on earthquake occurrence from
prehistoric times to the present. NGDC
also maintains databases on other
parameter, such as topography,
magnetics, gravity, and other topics.
Electric logs for many petroleum wells
can be obtained from one Of several well
log libraries in the U.S.
Surface and borehole geophysical
surveys.
Available through online services or on CD ROM. Includes
references contained in the Bibliography and Index of
Geology. Available at many university libraries.
The GEODEX is a hierarchically organized system
providing easy access to the geotechnical literature. Can
be purchased on a subscription basis, or available at many
university libraries.
Published as two volumes (Grawlewska, 1969; Jenkins and
Brown, 1979), and can be found in many earth science
libraries.
Aeromagnetic maps (1:24,000): Branch of Geophysics, MS
964; 303/236-1343. Earthquake data: National Earthquake
Information Center (NEIC), MS 967; 303/236-1500 (recent
earthquakes only). Landslide data: Landslide Information
Center, MS 966; 303/236-1599. Magnetic Declination
Information: Branch of Global Seismology and
Geomagnetism, MS 967; 303/236-1369. GEOMAG
contains current and historical magnetic-declination
information. Current or historical values back to 1945 can
be obtained by calling 800/358-2663. The entire GEOMAG
database can also be accessed via modem.
NGDC is a central source for dissemination of earthquake
data and information for both technical and general users,
except for recent earthquakes (see USGS above). For a
fee, a search can be made for one or more of the following
parameters: (1) geographic area (circular or rectangular
area), (2) time period (starting 1638 for U.S.), (3)
magnitude range, (4) date, (5) time, (6) depth, and (7)
intensity (modified Mercalli).
The geophysical logs are indexed by survey section. To
obtain information on wells in a given area, a list of
townships, ranges, and section numbers must be compiled.
Proprietary geophysical data can sometimes be obtained
from private survey firms if the original client authorizes
release of the information. Even if the information cannot
be released, firms may be willing to provide references to
published information they obtained before the survey, or
information published as a result of the survey.
individual soil series can be found in the text portion of
an SCS soil survey, but is scattered through different
sections and tables in the report.
Existing site-specific subsurface geologic information
typically will not be available unless water wells or oil
and gas exploration holes are located on or near the
site. If water well or exploration boreholes are known or
thought to exist at the site in nearby locations, available
well/borehole logs should be obtained. Water well drill
log files are typically maintained by state water resource
agencies (Table 6-6), and state geological surveys or oil
and gas agencies should be the first place contacted for
information about other possible borehole logs. Geo-
physical survey firms and well log libraries are other
possible sources for subsurface borehole data (Table 6-4).
If a site is located near a numbered county, state, or
federal highway, the appropriate agency should be con-
tacted to identify possible subsurface information col-
lected as part of road or highway construction projects.
Table 6-4 identifies geologic indexes and databases for
geologic and geotechnical literature, if a more extensive
literature search should be appropriate for a site.
Major areas of holocene faulting can be identified by
consulting the series of maps that identify young faults
(U.S. Geological Survey, 1978), which can be obtained
from USGS Map Sales (Table 6-2). Figure 4-1 identifies
major potential seismic impact zones in the United
States. If the site is located within or near any of the
71
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Table 5-5. Types of Data Available on SCS Soil Series
Description and Interpretation Sheets
Soil Series Description Sheet
Taxonomte Class
Typical soil profile description
Range of characteristics
Competing series
Geographic setting
Geographically associated soils
Drainage and permeability
Use and vegetation
Distribution and extent
Location and year series was established
Remarks
Availability of additional data
Soil Survey Interpretations Sheet8
Estimated Soil Properties (major horizons)
Texture class (USDA, Unified, and AASHTO)
Particle size distribution
Liquid limit
Plasticity Index
Moist bulk density (g/cm3)
Permeability (inJhr)
Available water capacity (inJIn.)
Soil reaction (pH)
Salinity (mmhos/cm)
Sodium absorbtion ratio
Cation exchange capacity (Me/100g)
Calcium carbonate (%)
Gypsum (%)
Organic matter (%)
Shrink-swell potential
Corrosivity (steel and concrete)
Erosion factors (K,T)
Wind erodability group
Flooding (frequency, duration, months)
High water table (depth, kind, months)
Cemented pan (depth, hardness)
Bedrock (depth, hardness)
Subsidence (initial, total)
Hydrologic group
Potential frost action
Use/Suitability Ratings
Sanitary facilities
Source material
Community development
Water management
Recreation
Crop/pasture capability and predicted yields
Woodland suitability
Windbreaks (recommended species for planting)
Wildlife habitat suitability
Potential native plant community (rangeland or forest)
a Units indicated are those used by SCS.
Note: Boldface entries are particularly useful for evaluating
contaminant transport.
Table 6-6. Hydrologic, Wetland, and Climatic Data Sources (U.S. EPA, 1993c; Sara, 1994)
Source Type(s) of Information Comments
Hydrologic Information Unit,
USGS,
419 National Center,
Reston, VA 22092;
703/648-6817
Office of Water Data
Coordination (OWDC),
USGS, 417 National Center,
Reston, VA 22092;
703/648-5023
National Water Data Exchange
(NAWDEX), USGS, 421
National Center, Reston, VA
22092; 703/648-5677
Locations and phone numbers of
USGS Water Resource Division
District Offices; state water-resource
investigation summary reports.
Information on current federal water
data acquisition activities. Selected
publications are also available.
NAWDEX Master Water Data Index
and Water Data Source Directory
contain information on more than
460,000 water data sites and more
than 800 organizations that collect
water data respectively.
Water Resources Investigations in [State, Year] are booklets
describing projects and related publications by USGS and
cooperating agencies. Summary folders by the same name
show location of hydrologic-data stations and selected
publications for the state. Also serves as reference office for
Water-Resources Investigation reports released before 1982
that were not issued as Open-File Reports (Table 6-4) or
made available through NTIS (Table 6-1).
Available publications include: (1) National Handbook of
Recommended Methods for Wate'r-Data Acquisition, (2) Index
to Water Data Activities in Coal Provinces in the U.S. (5
Volumes), and (3) Guidelines for Determining Flood Flow
Frequency.
The NAWDEX Program Office and its 75 Assistance Centers
(which includes all USGS Water Resources Division District
Offices) help water-data users locate and obtain data,
including bibliographic search in the WRSIC database (see
below). Fees for services depend on type of request and the
organization fulfilling the request.
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Table 6-6. Hydrologic, Wetland, and Climatic Data Sources (U.S. EPA, 1993c; Sara, 1994) (continued)
Source Type(s) of Information Comments
National Water Data Storage
and Retrieval System
(WATSTORE)
Water Resources Scientific
Information Center (WRSIC),
USGS, 425 National Center,
Reston, VA 22092;
703/648-6821
USGS Water Resources
Division District Offices
(WRD-DO)
USGS Hydrologic Publications
Federal Emergency
Management Agency,
Rood Map Distribution Center,
6930 (A-F) San Thomas Rd.,
Baltimore, MD 21227-6227;
800/358-9616
U.S. Army Corps of
Engineers (COE),
Washington, DC 20314-1000;
202/272-0660
Fish and Wildlife Service,
U.S. Department of the
Interior,
1849 C St. NW, Washington,
DC 20240; 202/208-5634
State Water Resource
Agencies
National Ground Water
Information Center (NGWIC),
National Ground Water
Association,
6375 Riverside Drive,
Dublin, OH 43017;
800/332-2104
Climatic Data
National Climatic Data Center
(NCDC), Federal Building, 37
Battery Park Ave., Asheville,
NC 28801-2733; 704/259-0682
Gale Research Company
(1985)
U.S. Department of Agriculture
All types of water data are accessed
through the WATSTORE computer
database.
Abstracts of water resources
publications throughout the world.
State-level water resources
investigation reports and data.
Various Series: Water-Supply Papers,
Water-Resource Investigation
Reports, Hydrologic Investigation
Atlases; State Hydrologic Unit Maps.
100-year floodplain maps are
available for most municipal areas at
a scale of 1:24,000. In some areas
more detailed FEMA Flood Insurance
Studies are available that delineate
500-year floodplain.
Location of navigable waters and
wetlands.
National Wetland Inventory (NWI)
maps.
Well logs, state-collected hydrologic
data.
Computerized, on-line bibliographic
database. Search by author,
keyword, and date. Abstracts are
relatively short and nontechnical.
The National Oceanic and
Atmospheric Administration's (NOAA)
NCDC collects and catalogs nearly
all U.S. weather records. Hatch
(1988) provides a selective guide to
climatic data sources.
Climates of the States - NOAA
Narrative Summaries, Tables, and
Maps for Each State.
County-level, local meteorological
data.
NAWDEX (above) or USGS Water Resource Division District
Offices (see below) should be contacted for information on
availability of specific types.of data, acquisition of data or
products, and user charges.
Bibliographic information available through publications and
computerized bibliographic information services. For additional
information contact Branch of Water Information Transfer.
WRD-DOs serve as NAWDEX Assistance Centers, and can
provide up-to-date listings of water resource investigation
publications and maps by USGS and cooperating agencies.
Publications available from USGS Book and Open File
Reports Section (Table 6-4); maps and atlases available from
USGS Map Distribution Section (Table 6-2).
Flood Insurance Rate maps and other flood maps can be
obtained from FEMA. These maps are also available from
USGS WRD-DOs and commonly from other agencies such as
the relevant city, town, or county planning office.
The COE has primary responsibility for regulation of wetlands.
Methods for delineating wetlands are contained in COE
(1987), and Federal Interagency Committee for Wetland
Delineation (1989). The nearest COE District office should be
contacted to identify available information.
The NWI has been completed largely using remote sensing
techniques and other available resource data.
Hydrologic data can often be accessed through NAWDEX.
Ground-water well logs commonly must be obtained from the
appropriate state agency. Giefer and Todd (1972, 1976)
identify water publications by State Agencies.
Accessible to members and nonmembers through computer,
modem, and telecommunications software. Photocopying
service of most references and interlibrary loan service
available.
NCDC services include: (1) publications, reference manuals,
and data report atlases, (2) data and map reproduction in
various forms (paper copy, microfiche, magnetic tape,
diskette), (3) analysis and preparation of statistical.summaries,
(4) evaluation of data records for specific analytical
requirements, (5) library search for bibliographic references,
abstracts and documents, and (6) referral to organizations
holding requested information.
Provides general summary statistics and maps.
Published SCS county soil surveys provide summary
precipitation and temperature data. Agricultural Research
Stations funded by the USDA Cooperative Extension Service
often collect climatic data in areas where agricultural research
is being done.
73
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shaded areas on this figure, more detailed information
about historic seismic activity in the area should be
obtained. The National Oceanic and Atmospheric Admini-
stration's National Geophysical Data Center (NGDC) in
Boulder, Colorado, (Table 6-4) is the primary source of
information for earthquake data. If there has been very
recent seismic activity in the area, the USGS's National
Earthquake Information Center (NEIC), in Denver, Colo-
rado should be contacted (Table 6-4).
General information on geotechnical characteristics of
near-surface soils at a site can be obtained from soil
survey information (USCS classification of major soil
horizons, liquid limit, plasticity index, etc.—see Table
6-5). Site-specific geotechnical information, however, is
not likely to be available unless data from highway
adjacent or near the site exist (see discussion above).
The availability of such information must be addressed
during site-specific investigations (see Section 6.4.3).
6.3.3 Hydrologic, Wetland, and Climatic
Information
Table 6-6 identifies major information on hydrology,
floodplains, wetlands, and climatic data. In general, ex-
isting hydrologic data fall into four primary categories:
(1) stream discharge, (2) stream water quality, (3)
ground-water levels, and (4) ground-water quality. Typi-
cally site-specific data will not be available, but relevant
data from nearby or hydrogeologically similar monitoring
points should be obtained. The state district offices of
the USGS's Water Resources Division, which serve as
local assistance centers for USGS's National Water
Data Exchange (NAWDEX) is the best starting point for
identifying available hydrologic data that might be rele-
vant to a specific site. These offices are primarily re-
sponsible forfloodplain mapping, so they also should be
asked about the availability of floodplain maps for the
area of interest. Published floodplain maps also can be
obtained from the FEMA's Flood Map Distribution Cen-
ter (Table 6-6) and also might be available from city,
town, or county planning offices.
If a National Wetland Inventory (NWI) map is not avail-
able for the site being evaluated, a published SCS soil
survey will indicate the possible presence of wetlands.
Soil series located within a site should be checked
against the list of "hydric" soil series that has been
developed by SCS (National Technical Committee for
Hydric Soils, (1991). If wetlands are known or suspected
to be present within or near a site, more detailed site
investigations will be required (see Section 6.4.5). An
SCS soil survey also will indicate whether all or parts of
a site are located within a floodplain, but more detailed
investigations may be required to delineate the 100-year
floodplain if a FEMA flood map is not available (see
Section 6.4.6).
6.4 Site-Specific Data Collection
The characteristics of a site as indicated by existing
information about the site and its surrounding area will
determine the type and extent of field investigations that
will be required. As site geology and hydrogeology in-
crease in complexity, more sophisticated and expensive
site investigation techniques are required, as shown in
Figure 6-1. The discussion in this section assumes that
the ground-water system is relatively simple, consisting
of a single unconfined aquifer in unconsolidated materi-
als (Type I in Figure 6-1). Field investigation techniques
for this type of site are relatively simple and inexpensive,
requiring equipment ranging from handheld soil augers
to power-driven equipment that is hand-portable or can
be mounted on a pickup truck. Although a detailed dis-
cussion of field methods for investigation of more com-
plex sites is beyond the scope of this handbook, Table
6-7 identifies major recent references where information
on such techniques can be found. Also, Section 6.4.6
identifies major references that address methods for
site-specific geotechnical investigations, and Appendix
C identifies manufacturers and distributors of equipment
for site-specific data collection.
Table 6-7. Guide to Major Recent References on
Environmental Field Investigation Techniques8
Reference Description
ASTM (1994) Standard Guide to Site Characterization for
Environmental Purposes. Text and
appendices identify hundreds of ASTM
standard test methods for field and
laboratory methods. See also ASTM D420
(Standard Guide to Site Characterization for
Engineering, Design and Construction
Purposes).
Nielsen (1991) Practical Handbook of Ground-Water
Monitoring. Comprehensive handbook on
ground-water monitoring methods, which
also includes chapters on soil sampling and
vadose zone monitoring.
Sara (1994) Standard Handbook of Site Assessment for
Solid and Hazardous Waste Facilities.
Comprehensive handbook on solid and
hazardous waste facility assessments.
U.S. EPA (1987) Technology Briefs: Data Requirements for
Selecting Remedial Action Technology.
Sections relevant to design of sewage
sludge surface disposal sites include:
grading, revegetation, diversion/collection
systems, and surface water/sediment
containment barriers. Summary tables for
each technique identify (1) data needs, (2)
purpose of the data, (3) collection methods,
and (4) costs.
U.S. EPA (1988a) Guide to Technical Resources for the Design
of Land Disposal Facilities. Most relevant
sections related to sewage sludge surface
disposal sites include sections on
foundations (useful if the potentially unstable
areas are present, and run-on/runoff
controls.
74
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Table 6-7. Guide to Major Recent References on Environ-
mental Field Investigation Techniques8 (continued)
Reference
Description
U.S. EPA (1991c) Site Characterization for Subsurface
Remediation. Covers methods for
soil/geologic, ground-water and vadose-zone
hydrologic characterization and monitoring
techniques with a focus on applications for
remediation of contaminated sites. Chapters
2 through 9 cover techniques that are
applicable to any type of environmental field
investigation.
U.S. EPA (1993a) Subsurface Field Characterization and
Monitoring Techniques. 2-volume document
providing summary information on more than
280 specific field investigation and
monitoring techniques. Volume I covers solid
and ground-water and Volume II covers the
vadose zone, chemical field screening and
analytical techniques. Appendix C contains a
comprehensive bibliography of major
references on subsurface characterization,
monitoring and analytical methods.
Reference
Description
U.S. EPA (1993b) Solid Waste Disposal Facility Criteria:
Technical Manual. Chapter 2 covers methods
for identification and engineering design
considerations related to floodplains,
wetlands, fault areas, seismic impact zones
and unstable areas. Chapter 5 covers
ground-water monitoring well design and
construction and sampling.
a See end of Section 6.4.6 for identification of major references for
geotechnical characterization.
Least Complex
CONCEPTOALHYpjROG|OLOGY.,,
SINGLE LAYER/HYDRAULIC CONDUCTIVITY
LAYEREDIMULTIPLE
HYDRAULIC CONDUCTIVITIES
Moderately Complex
LAYERED/MULTIPLE HYDRAULIC
CONDUCTIVITIES Ct GRADIENTS
Highly Complex
V
Phase I Investigation
Phase II Investigation, Complete:
Stratigraphy/Lab Testing
• Piezometers
• Cross-sections
• Potentiometric Map
• Conceptual Model
Locate Monitoring Wells
Phase I Investigation
Phase II Investigation, Complete:
• Geophysics- Surface & Downhole
• Stratigraphy/Lab Testing
• Hydraulic Conductivities, LabXField
• Nested Piezometers
• Cross-sections/Stratigraphic Maps
• Potentiometric Map
• Flow net
• Conceptual Model
Locate Monitoring Wells
Phase I Investigation
Phase II Investigation, Complete:
• Geological Mapping
• Geophysics- Surface & Downhole
• Core Drilling/Angle Holes
• 3-D Geology/Lab Testing
• Infield Packer Tests/Lab Perms.
• Nested Piezometers
• Cross-sections & Stratigraphic Maps
• Potentiometric Surfaces
• Multiple Flow Nets
• Geochemistry of Ground-water
• Conceptual Models
Locate Monitoring Wejls
Figure 6-1. Site complexity indicators for selection of assessment techniques (Sara, 1994).
75
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6.4.1 Site Land and Topographic Survey
An accurate boundary survey and topographic base map
are essential for developing a base map for plotting obser-
vation points during field investigations and for design
of pollution control measures such as terraces and sedi-
ment ponds. Where a site comprises tens of acres, a scale
of 1:1,200 (1 in. = 100 ft) or 1:2,400 (1 in. = 200 ft) with
contour intervals ranging from 1 to 5 ft will usually pro-
vide the best base map. Sites involving hundreds of
acres may require larger scales (up to 1:6,000) to pre-
vent base map size from becoming unmanageable. In
very flat areas, contour intervals of 1 or 2 ft are required
to accurately delineate subtle topographic variations. In
steep areas, larger contour intervals are appropriate.
Topographic maps at scales of 1:2,400 or larger can be
created using field surveys or photogrammetry from low-
altitude aerial photographs. Cost estimates from surveyors
and commercial aerial photography/photogrammetry
companies should be obtained. If the local yellow pages
do not list any photogrammetry firms, the American
Society of Photogrammetry and Remote Sensing (ASPRS)
might be able to provide the address and phone number
of firms that work in the vicinity of the site. Table 6-3
includes ASPRS's address and phone number.
6.4.2 Soil and Geologic Characterization
Although published soil surveys provide much useful
information for preliminary site selection, they generally
are not adequate for site-specific design of sludge sur-
face disposal sites. For example, areas of similar soils
that cover less than 4 or 5 acres are generally not shown
on published SCS county soil surveys. For site-specific
evaluation and design purposes, it is desirable to iden-
tify areas of similar soil characteristics that are as small
as an acre. The SCS may be able to prepare a more
detailed soil survey of a site that has been selected for
surface disposal of sludge. If SCS has a large backlog
of requests, however, obtaining a more detailed soil
survey can take months. A detailed soil survey prepared
by consulting soil scientists will be more expensive, but
will usually involve less delay. If a private consultant
conducts the soil survey, the person or persons actually
carrying out the survey should be trained in soil mapping
and classification methods used by SCS for the National
Cooperative Soil Survey.
As discussed in Section 6.4.3 (Hydrogeologic Charac-
terization), where the permanent or seasonal high
water table is within 5 ft of the ground surface, crea-
tion of a water table map by a soil scientist based on
observation of soil morphology can be a very cost-
effective way to obtain an initial characterization of a
site's hydrogeology.
Soil mapping is usually conducted using handheld
augers or tube probes with subsurface observations
limited to depths of 5 ft or less. Once a detailed soil
survey has been prepared, sites for deeper sampling
can be selected to evaluate whether surface topography
and soil types correlate with geologic characteristics
below the soil weathering zone (which generally extends
to a depth of 5 ft or less), and for more detailed hydro-
geologic and geotechnical characterization.
Test pits are the best way to directly examine subsurface
lithology and sedimentary features that affect the poten-
tial for transport: of pollutants in the near surface be-
cause both lateral and vertical variations can be
observed, and core samples allow direct observation of
vertical changes in subsurface lithology and sedimen-
tary features. Provided that gravel or other rock frag-
ments are absent, the most efficient and cost-effective
way to collect deeper cores is usually by using truck-
portable power-driven equipment. Such equipment can
involve hand-held electric, gasoline-powered, or com-
pressor-operated vibrating hammers for driving rods
with probes affixed to the end (Figure 6-2a) and using a
special jack to pull the probe to the surface (Figures 6-2b
to 6-2d). Also, hydraulic probes can be mounted to a van
or pickup truck (Figure 6-3) or on trailers or tractors.
Probes driven with handheld power equipment typically
yield cores of 1 in. in diameter. Mounted hydraulic probes
can provide cores of up to 2 in. Larger diameter cores
are generally easier to describe because changes in
color, texture, and other features are more discernable.
Boulding (1994) and U.S. EPA (1991 a) provide guidance
on the description and interpretation of subsurface cores.
Where the subsurface contains large rock fragments, it
may still be possible to collect large-diameter cores (2
inches) using larger drill rigs. Otherwise, drilling meth-
ods that do not collect cores may have to be used. Also
collection of core deep core samples (generally greater
than 10 meters) generally requires use of drill rigs rather
than hand-powered or truck-mounted equipment.
Note: All deep boreholes represent channels for prefer-
ential movement of leachate from sewage sludge and
therefore should be filled with bentonite or an alternative
suitable grout. Shallow boreholes within the sludge sur-
face disposal site or that might receive surface runoff
from the site also should be plugged at the surface or
grouted. Figure 6-4 illustrates a grouting procedure us-
ing a rigid pipe and flexible tremie tube. Where holes do
not extend to the water table, plugging of the upper part
of the hole with soil material may be adequate as a
alternative to grouting.
6.4.3 Hydrogeologic Characterization
Hydrogeologic field investigations should focus on de-
veloping a three-dimensional understanding of the
ground-water flow system so as to determine: (1) the
direction in which pollutants from sewage sludge would
travel if it entered an aquifer, (2) the speed with which
the pollutants would move, and (3) the best location for
76
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Chuck
v Spool
(b)
Lever handle
AT-99
(a)
(d)
Figure 6-2. Core sampling with handheld power driver: (a) hammer driver (courtesy Solinst Canada); (b) positioning probe rod jack
for manually retrieving deep core samples; (c) chuck in down position; (d) pulling position, level down (courtesy of
Geoprobe Systems).
77
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54'
48"
31"
119'
54" stroke allows more room
for operation and longer probe rods.
Figure 6-3. Hydraulic probes mounted in van and pickup truck (courtesy of Geoprobe Systems).
Grout
'/ '//////
(a) Installation (b) Tube Removal (c) Grouting
Rgura 6-4. Narrow-diameter borehole grouting procedure using rigid pipe and internal flexible tremie tube.
78
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ground-water monitoring wells. Generally, hydro-
geologic characterization should be conducted by a
qualified ground-water scientist, defined by EPA as
an individual with a baccalaureate or post-graduate
degree in the natural sciences or engineering who
has sufficient training and experience in ground-
water hydrology and related fields, as may be dem-
onstrated by State registration, professional
certification, or completion of accredited university
programs, to make sound professional judgements
regarding ground-water monitoring, pollutant fate and
transport, and corrective action. 40 CFR 503.21 (I).1
This section focuses on relatively simple and inexpen-
sive techniques for characterizing the ground-water sys-
tem using: (1) soil morphology where the seasonal high
water table is within 5 ft of the ground surface; (2)
multiple piezometer installations to develop a three-di-
mensional picture of hydraulic head distribution; and (3)
flow net analysis to determine the direction and speed
of ground-water flow. For a Type I hydrogeologic setting
(Figure 6-1), this information can be obtained using
handheld or portable power-driven equipment similar to
that described for soil and geologic characterization in
Section 6.4.2. As noted above, references in Table 6-7
provide information on field investigation techniques for
more complex sites.
Depth to Water Table Based on Soil Morphology
Soil color serves as a good indicator of soil-water con-
ditions, with grey colors of 2 chroma or less on a Munsell
Soil Color Chart typically indicating a dominance of
reducing conditions and bright colors indicating oxidiz-
ing conditions. In 1992 the SCS adopted an extensively
revised and improved approach to describing and inter-
preting soils that are saturated during all or part of the
year (Soil Survey Staff, 1992). The depth and pattern of
redoximorphic soil features allow estimation of the depth
of the permanent and seasonal high water table. Sea-
sonal perched water tables also can be identified based
on soil morphology, even if no water is perched at the
time of observation. Boulding (1994, Appendix C) and
Vepraskas (1992) provide more detailed guidance on
description and interpretation of soil redoximorphic
features.
Where the water table is within five feet of the ground
surface (which is common in large areas of the eastern
United States) a detailed water table map can be devel-
1 The Part 503 rules do not explicitly state that hydrogeologic char-
acterization be done by a qualified ground-water scientist, never-
theless it wouild make sense to have such a person conduct or
supervise this aspect of the field investigations. A qualified groud-
water scientist fe required for developing a ground-water monitoring
program or certify that placement of sewage sludge on an active
sewage sludge unit will not contaminate ground water if graound-
water is not monitored at units that do not have a liner and leachate
collection system (40 CFR 5-3.24(n)).
oped at relatively low cost if a qualified soil scientist is
available (see Section 6.4.2). A grid spacing should be
chosen that will provide sufficient data points for con-
touring, but not so many that field work cannot be com-
pleted in a day or two. A general rule of thumb would be
20 to 30 soil observations using handheld equipment to
record the following information: (1) texture and thick-
ness of A horizon, (2) texture and thickness of E horizon
(if present), (3) depth to B or C horizon, and (4) depth
to seasonal high and permanent water table. If a ground
survey is used to prepare the topographic base map for
the site (Section 6.4.1), placement of stakes at the
chosen grid spacing and measurement of actual eleva-
tion of the grid points would facilitate field work and
plotting of data observations. Section 6.5.2 discusses
how data collected by this survey can be used to evalu-
ate soil attenuation capacity and the potential for pollut-
ant transport.
Three-Dimensional Mapping of Hydraulic Head
Accurate characterization of the ground-water flow sys-
tem requires not only a delineation of the water table
surface, but also measurement of hydraulic head at
different depths in an aquifer. Figure 6-5 shows why this
is necessary, In areas of ground-water recharge, hy-
draulic head decreases with depth (wells a and b in
Figure 6-5). In ground-water discharge zones, hydraulic
head increases with depth (wells dand ein Figure 6-5).
Areas where lateral flow is dominant are characterized
by small changes in hydraulic head with depth. Further-
more, variations in the hydraulic conductivity of different
aquifer materials cause changes in the distribution of
hydraulic head and, consequently, changes in the direc-
tion of ground-water flow. This effect is illustrated in
Figure 6-6 where piezometers (discussed below) have
been set in three different aquifer materials at each
observation point. The water table surface (Unit A) indi-
cates a general flow direction from an elevation of 210
ft on the west edge to 180 ft on the east edge. Unit C in
Figure 6-6, however, shows a head distribution favoring
ground-water flow south to southeast. Section 6.5.2 dis-
cusses further use of flow nets to evaluate the direction
of ground-water movement based on three-dimensional
pressure head measurements.
Pressure head is measured using a piezometer. The two
major types of piezometers are (1) open-tube or stand-
pipe piezometers, in which ground water rises to the
level dictated by the pressure head, and (2) pore pres-
sure piezometers, which measure pressure directly. Any
cased well can function as an open-tube piezometer,
provided that the borehole around the casing is well
sealed and the well screen or casing slotting at the
bottom is short (5 feet or less) so as to prevent mixing
of hydraulic heads. Pore pressure piezometers can be
further classified as:
79
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RECHARGE AREA
a
ft b
DISCHARGE AREA
d e
SCREENED
INTERVAL
X
X
Figure 6-5. Cross-sectional diagram showing depth variations of water level as measured by piezometers located at various depths
(Mills et al., 1985).
Potentiometric Maps
For Each Layer1
C ,
Piezometers Resultant Head Level Contour Maps
Figure 6-6. Ground-water contour surfaces using multilevel piezometer measurements (Sara, 1994).
80
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• Electrical resistance piezometers use strain gauge
technology to sense the pressure of a fluid applied
to a diaphragm.
• Vibrating wire piezometers, which generate electrical
signals at the surface as the tension in a wire that is
connected to a diaphragm situated behind a filter
stone changes in response to higher or lower pore
pressure,
• Pneumatic piezometers, which use a pressure
transducer to measure changes that water pressure
has exerted against a diaphragm into which air has
been forced.
• Hydraulic piezometers, which consist of one or two
water-filled tubes that run from the surface to a ce-
ramic or porous stone tip; pressure changes are read
from a gage at the surface (mercury manometer,
transducer, or Bourdon gage).
Pore pressure probes can be driven into the ground
manually or hydraulically (using a cone-penetration rig)
to obtain continuous pore pressure profiles that also
allow interpretations of subsurface stratigraphy (Figure
6-7). As shown in Figure 6-7, equilibrium pore pressure
is often inferred rather than measured directly, because
this requires stopping the probe and waiting for equili-
bration to occur, which may take a long time (especially
in clays). However, in clean and dirty sands and gravels
with less than 40% fines measurements of equilibrium
pore pressure is rapid and useful. A series of poten-
tiometric maps with depth (as shown in Figure 6-6) could
be developed with relative ease, however, by stopping
to measure equilibrium pore pressure at specified inter-
vals in multiple probe tests. The advantage of this
method is that numerous hydraulic head measurements
can be obtained over a relatively short period. The cau-
tionary note in Section 6.4.2 concerning grouting of
boreholes applies here as well. Pore pressure probes
can also be driven to the desired depth without profiling
as .permanent monitoring installations.
The other simple way to develop hydraulic head profiles
with depth is to install permanent piezometer nests. This
involves placing piezometers at different depths in a
cluster. The simplest way to do this is to push a small-
diameter, open-hole drive-point or pore pressure probe
attached to a metal standpipe to the desired depth.
These can be driven manually using a weighted driver
(Figure 6-8a) or a crank driven device (Figure 6-8b).
Portable power-driven drivers and truck-mounted hy-
draulic drivers such as those illustrated in Figures 6-2a
and 6-3 also can be used to install piezometers.
The advantage of permanent piezometer installations is
that changes in hydraulic head distributions with time
can be measured. Measurement of seasonal changes
in ground-water levels~and responses to rainfall events
are an important part of characterizing the ground-water
flow system. With open-hole piezometers such changes
are usually measured using a tape or electric water-level
probe. Measurements using permanent pore pressure
piezometers can be made manually by reading the ap-
propriate gage or signal, or recorded automatically with
a datalogger. An advantage of open-hole piezometers is
that they also can be useful for ground-water quality
monitoring (see Chapter 9). Pausing at intervals during
the driving of the first piezometer in a cluster will provide
an indication as to whether it is located in a recharge,
discharge, or lateral-flow zone. These measurements
then can be used to determine the best depth for place-
ment of shallower piezometers in the cluster.
If subsurface materials are soft enough to be penetrated
by drive points (silts, sands, clays) and course frag-
Figure 6-7. Typical pore pressure sounding diagram for a layered soil; u0 = equilibrium pore pressure (courtesy of Hogentogler &
Co., Inc.).
81
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AT-11B
Drive Cap
Driver
Body
Handle
AT-10B
Probe Rod
Figure 6-8. Manual piezometer installations methods: (a) weighted driver (courtesy of Geoprobe Systems); (b) crank-driven (courtesy
of Hogentogler & Co., Inc.).
ments or very dense layers such as glacial till are ab-
sent, installation of piezometers is relatively inexpensive
(hundreds vs. thousands of dollars for conventional
monitoring well installations). If standard drilling equip-
ment such as hollow-stem augers must be used, costs
will be much higher but still less than for installation of
conventional monitoring wells if capsule-type piezome-
ters with flexible tubing are used. Section 10.4.2 dis-
cusses installation of permanent ground-water quality
monitoring wells.
The location and number of multilevel piezometer meas-
urements or installations will depend on the complexity
of the site. At a minimum, measurements should be
taken at the highest and lowest topographic points on
the site and at several intervening points.
6.4.4 Wetland Identification and Delineation
Site-specific investigations of potential sewage sludge
surface disposal sites will often require a determination
of the presence or extent of wetlands. For example, U.S.
EPA (1990b) found that 79 percent of the 110 sanitary
landfills in the State of New York for which National
Wetland Inventory (NWI) maps were available, either
included or were within 1/4 mile of a wetland. Similarly,
U.S. EPA (1990a) in a study of 1,153 sanitary landfills in
11 states, found that 72 percent contained wetlands or
were within 1/4 of a mile.
The term wetlands includes swamps, marshes, bogs,
and any areas that are inundated or saturated by ground
water or surface water at a frequency and duration to
support a dominant vegetation adapted to saturated soil
conditions. As noted in Section 6.3.3, the presence or
absence of hydric soils (e.g., soils that are wet long
enough to periodically produce anaerobic conditions) in
a soil survey of the site will provide a good indication of
whether a more detailed investigation will be required. If
a wetland is determined to be on the site, its boundaries
must be accurately delineated.
Accurate wetland delineation typically requires assess-
ment by a qualified and experienced multidisciplinary
team to identify: (1) the limits of the wetland boundary
based on hydrology, soil types, and plants types; (2) the
type and relative abundance of vegetation, including
trees; and (3) rare, endangered, or otherwise protected
species and their habitats, if present. Many methods
have been developed for assessing wetlands. The main
82
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guidance manuals for wetland delineation for regulatory
purposes are the Corps of Engineers Wetlands Deline-
ation Manual (COE, 1987) and the Federal Manual for
Identifying and Delineating Jurisdictional Wetlands
(Federal Interagency Committee for Wetland Deline-
ation, 1989). The latter manual places greater emphasis
on assessment of the functional value of wetlands,
along the lines of earlier work by the U.S. Fish and
Wildlife Service (USFWS, 1984).
Appendix C in U.S. EPA (1990c) provides summary
information on more than 30 methods for assessment of
wetland functions and values. Phillips (1990) describes
a quantitative wetness index for use when field indica-
tors of wetness are ambiguous or contradictory. Lyon
(1993) may be useful as a supplemental reference for
wetland identification and delineation. Finally, Maus-
bach (1994) provides a recent review of the historical
development and current status of criteria developed by
the SCS for classification of wetland soils, and notes that
definitions are continuing to evolve as SCS develops
and tests regional indicators of hydric soils.
6.4.5 Floodplain and Other Hydrologic
Characterizations
As noted in Section 6.3.3, whether a site is located
wholly or in part within a 100-year floodplain can be
initially determined using a FEMA floodplain map or
SCS soil survey. If there is any reason to suspect that
actual sewage sludge disposal will occur on the flood-
plain, more detailed investigations will be required to
accurately delineate the floodplain boundary. If disposal
within the floodplain cannot be avoided, then the surface
disposal site must be designed to include protective
measures such as embankments or levies so that active
sewage sludge units: (1) will not restrict the flow of the
100-year flood, (2) will not reduce the temporary water
storage capacity of the fjoodplain, or (3) will not result in
washout of pollutants that pose a hazard to human
health and the environment.
Site-specific floodplain investigations may require
analysis of meteorological and streamflow records; up-
stream topography, soils, and geology; aerial photo-
graph interpretation; and assessment of existing and
anticipated changes in watershed land use. The Inter-
agency Advisory Committee on Water Data (Hydrology
Subcommittee, 1982) provides guidelines for determin-
ing flood flow frequency using stream gauge records.
The U.S. Army Corps of Engineers (COE, 1982) has
developed several numerical models to: aid in the pre-
diction of flood hydrographs (HEC-1); create water sur-
face profiles due to obstructions for evaluating flood
encroachment potential (HEC-2); simulate flood control
structures (HEC-5); and gauge river sediment transport
(HEC-6). The HEC-2 model is not appropriate for simu-
lation of sediment-laden braided stream systems or
other intermittent/dry stream systems that are subject to
flash-flood events. Standard runoff and peak flood hy-
drograph methods would be more appropriate for such
conditions to predict the effects of severe flooding.
6.4.6 Geotechnical Characterization
Sewage sludge monofills and dedicated surface dis-
posal sites that involve design of foundations, liners and
leachate collections systems, and dikes/embankments
will require detailed subsurface exploration, including
sampling of subsurface solids and laboratory testing.
Subsurface exploration programs often use both indirect
and direct methods, with direct methods required to
confirm indirect observations. Indirect investigation
methods include remote sensing techniques, such as
aerial photograph interpretation (Section 6.3.1), and
geophysical techniques, such as DC resistivity, electro-
magnetic induction, ground-penetrating radar, and seis-
mic refraction. These methods do not require drilling or
excavation. Selection of the proper geophysical tech-
niques requires consideration of the purpose of the test,
the character of the subsurface materials, depth limits
of detection and resolution of possible methods, and
susceptibility of methods to electrical or vibrational
noise. While geophysical procedures can provide large
amounts of data at a relatively low cost, they require
careful interpretation that must be carried out by quali-
fied experts only. Furthermore, geophysical data must
be verified by direct procedures such as borings or test
pits. Chapter 1 of U.S. EPA (1993c) provides additional
information on remote sensing and surface geophysical
methods.
Direct investigation methods include drilling boreholes
and wells and excavating pits and trenches. Direct
methods allow the site's geologic conditions to be
examined and measured. Typically, boring logs should
provide descriptions of the soil strata and rock forma-
tions encountered, as well as the depth at which they
occur. In addition, the boring logs should provide stand-
ard penetration test results for soils and rock quality
designation results for rock core runs. The boring logs
also should record the intervals for, and the results of,
any field hydraulic conductivity testing conducted in the
borings.
Foundation soil stability assessments require field in-
vestigations to determine soil strength and other soil
properties. In clayey materials, in situ field vane shear
tests commonly are conducted in addition to collection
of samples of subsurface material for laboratory testing
of engineering properties. Soil samples can be obtained
either by split spoon or thin-walled tube. Split spoon
samples are disturbed and are of limited value other than
for identification and assessment of water content. The
thin-walled tube sample provides an undisturbed sample
that can be used for a wide variety of laboratory tests.
83
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Laboratory testing is conducted using representative soil
samples. Testing, as appropriate, to evaluate the embank-
ments, the foundation area, and areas under considera-
tion as a source for borrow material covers: (1) ASTM/
Unified Soil Classification System (ASTM D2487-93,
Test Method for Classification of Soils for Engineering
Purposes), (2) grain-size distribution, (3) shrink/swell
potential, (4) shear strength, (5) compressibility, (6) con-
solidation properties, (7) density and water content, (8)
moisture-density relationships, (9) dispersivity, and (10)
laboratory hydraulic conductivity. When evaluating foun-
dation materials and liner materials, additional signifi-
cant parameters for laboratory testing include cation
exchange capacity and mineralogy.
The scope of the subsurface exploration program will
vary depending on the complexity of the subsurface
geology, seasonal variability in site conditions, and the
amount of site information available. Typically, the inves-
tigator should drill an adequate number of borings
across the site to characterize the underlying deposits
and bedrock conditions and to establish a reasonably
accurate subsurface cross section. Depth of borings is
highly dependent on site-specific conditions. Typically,
however, the borings should extend below the antici-
pated site base grade or below the water table, which-
ever is deeper. A sufficient number of water table
observation wells and piezometers should be installed
to define both the horizontal and vertical ground-water
flow directions (Section 6.4.3). When subsurface hetero-
geneities are encountered that could lead to seepage or
loss in strength in the foundation, additional subsurface
exploration is sometimes necessary to identify and de-
termine the extent of these features.
U.S. EPA (1988a) provides more detailed guidance on
types of geotechnical information and on field and labo-
ratory methods required for design of surface disposal
sites; U.S. EPA (1986a) provides more detailed guid-
ance on design, construction, and evaluation of clay
liners. The following major references provide more de-
tailed information on subsurface exploration techniques
for geotechnical investigations: Bureau of Reclamation
(1989, 1990), Hanna (1985), Hathaway (1988),
Hvorslev (1949), USAGE (1984), and U.S. Naval Facili-
ties Engineering Command (1982).
Identification of Unstable Areas
U.S. EPA (1993d) classifies unstable areas that might
restrict suitability for solid waste disposal as natural and
manmade. Naturally unstable areas include:
• Expansive soils, which have a large percentage of
clays with a high shrink-swell potential (smec-
tite/montmorillonite groups, vermiculites, bentonite)
or with sulfate or sulfide minerals present in the soil,
make poor foundations. Such soils are readily iden-
tified by a soil survey. For example, any soils classi-
fied as vertisols (which have a high shrink-swell po-
tential) would probably be unsuitable at a surface
disposal site. Expansive soils tend to be found in the
arid western states.
• Soils subject to rapid settlement (subsidence) also
make poor foundations. Such soils include thick loess,
unconsolidated clays, and wetland soils. Loess, found
in the north central states, tends to compact when it
is wetted. Unconsolidated clays and wetlands, on the
other hand, subside when water is withdrawn.
• Areas subject to mass movement have rock or soil
conditions that are conducive to downslope move-
ment of soil, rock, and/or debris (either alone or
mixed with water) under the influence of gravity. Ex-
amples of mass movement include landslides, debris
slides and flows, and rock slides. These tend to occur
most commonly on steep slopes, but sometimes con-
ditions on gradual slopes favor mass movement.
• Karst terrains develop where soluble bedrock (typi-
cally limestone, but dolomite, and gypsum also might
be subject to such effects) forms a subterranean
drainage system where flow is concentrated in con-
duits. These areas tend to be characterized by cav-
erns and sinkholes and subject to unpredictable,
catastrophic rock collapse. The presence of sinkholes
and soluble bedrock at or near the surface are a clear
indication of site unsuitability. The absence of obvious
karst geomorphic features (i.e., sinkholes) where
limestone or other soluble bedrock is near the surface
is not sufficient to determine stability. Fracture trace
analysis using aerial photographs is an especially
useful method for characterizing karst terrain (Section
6.3.1). Additional investigations, perhaps using sur-
face geophysical techniques also might be required
if no alternatives to siting in a karst area are available.
Examples of human-induced unstable areas include:
• The creation of cut and/or fill slopes during construc-
tion of the sewage sludge surface disposal site can
cause slippage of existing soil or rock. At most sites
the amount of earth-moving conducted is likely to be
small enough that this will not be a major concern.
• Excessive drawdown of ground water can cause ex-
cessive settlement or bearing capacity failure of foun-
dation soils. Again, this will not be an issue at most
sewage sludge surface disposal sites; however, if a liner
and a leachate collection system are to be used, system
design should take this effect into consideration.
Another type of naturally unstable area includes disper-
sive soils where sodium-rich clays (which often also
have a high shrink-swell) tend to disperse when wetted,
allowing a form of subsurface erosion called piping.
If any of the above conditions exist at a site and alter-
native sites with fewer problems are not available, more
84
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detailed geotechnical field investigations will likely be
required. U.S. EPA (1993d) provides more detailed
guidance on the approach that should be taken to as-
sess site stability and design approaches for designing
for stable slopes. U.S. EPA (1987 and 1988a) identify
specific data needs and field and laboratory methods for
geotechnical evaluation and design of different types of
engineered structures.
6.5 Data Analysis and Interpretation
Analysis and interpretation of data from site-specific
investigations for a dedicated sewage sludge disposal
site focus on the following:
• Identification of areas of shallow ground water and
assessment of the ground-water flow patterns at the
site (Section 6.5.1).
• Provision of data required for establishing routine pol-
lution control measures at the site, mainly surface
runoff controls (Section 6.5.2).
• Documentation of the presence or absence of special
site conditions that might impose special regulatory
restrictions (Section 6.5.3) and, if present, presenta-
tion of data that show the limitations can be overcome
by one or more engineering design approach (Sec-
tion 6.5.4).
Computer modeling (Section 6.5.5) can facilitate all of
the types of analysis listed above.
6.5.1 Identifying Areas of Shallow Ground
Water and Ground-Water Flow Net
Analysis
The investigations described in Section 6.4.3 should
allow development of a relatively detailed water table
contour map, which in combination with the site topo-
graphic map will facilitate development of an unsatu-
rated zone thickness isopach map. Such a map can be
used in several ways, including: (1) to identify areas of
shallow ground water where it may be desirable to place
some fill to increase the depth of saturation in the sur-
face disposal site, or (2) to assess the relative attenu-"
ation capacity of the vadose zone within the surface
disposal site.
Ground-water flow net analysis is a relatively simple
graphical technique for gaining an understanding of
ground-water flow patterns using water-table surface
contour maps and three-dimensional hydraulic head
data collected using procedures described in Section
6.4.4. As a first approximation, the general direction of
ground-water flow at a site can be determined by draw-
ing flow lines perpendicular to the water table contours.
As illustrated in Figure 6-5, apparent directions of flow
may change with depth. Flow lines drawn perpendicular
to ground water equipotential contours should be con-
sidered only a first approximation because anisotropy in
the aquifer (e.g., sites where horizontal hydraulic con-
ductivity exceeds vertical hydraulic conductivity) will
cause flow lines to diverge from the perpendicular. Fig-
ure 6-9 illustrates such a divergence in a fractured rock
aquifer where vertical hydraulic conductivity is five times
the horizontal hydraulic conductivity.
In ground-water recharge areas (i.e., hydraulic head
decreases with increasing depth), it is important to rec-
ognize that pollutants entering the ground water will tend
to move downward in the aquifer as well as laterally.
Figure 6-10 illustrates this effect and shows how flow net
analysis can be used to estimate pathlines where lay-
ered aquifer materials have different hydraulic conduc-
tivities. In this figure, a cross section of the aquifer has
been drawn using the borehole logs from three, multi-
level piezometer installations, and equipotential lines
drawn using hydraulic head measurements at four or
five levels in each piezometer. The angle of refraction of
flow or equipotential lines is determined from the ratio of
the hydraulic conductivities, which equals the ratio of the
tangents of the angles formed by the flow lines. Figure
6-10 illustrates that the downward component of pollut-
ant transport increases as hydraulic conductivity de-
creases. A significant implication of this effect is that
downgradient ground-water monitoring wells that are
screened in the upper portion of an aquifer may miss a
pollutant plume in a recharge area, unless the aquifer
has very high hydraulic conductivity.
Flow net construction and analysis requires knowledge
of the hydraulic conductivity of aquifer materials. Hy-
draulic conductivity values also are required to estimate
how rapidly pollutants might move if they enter the
ground-water system. References in Table 6-7 should
be consulted for guidance on the selection of aquifer test
methods if field measurement of aquifer properties is
required.
This section emphasizes flow net analysis because it
provides a maximum amount of information about the
hydrogeologic system at relatively low cost if procedures
for collecting three-dimensional hydraulic head meas-
urements described in Section 6.4.4 are used. Flow nets
can readily be constructed manually, although use of
computers for contouring data and graphic analysis can
facilitate the process. Cedergren (1989), U.S. EPA
(1986b) and Sara (1994) are recommended for more
detailed guidance on construction and interpretation of
flow nets. Flow net construction in anisotropic aquifers
requires special procedures, which are covered in these
references. Use of flow nets for placement of ground-
water monitoring wells is discussed in Chapter 10.
6.5.2 Other Geotechnical Considerations
As noted in Section 6.4.6, some sewage sludge surface
disposal sites will not require extensive geotechnical
85
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ISOTROPIC AQUIFER
water-table /(=> %
contours
/
s*
$
ANISOTROPIC AQUIFER
water-table
contours
KY
b:
Figure 6-9. Effect of fracture anisotropy on the orientation of the zone of contribution to a pumping well (U.S. EPA, 1991b).
p.i7n p.-t7h
P I7c' P I7d
f-i/c f-i/g
R.OW NET FOR SILTY SAND.SAND UNITS & BEDROCK WITH DOWNWARD 1 1EADS
Pioynmotorc
riezometers
p'18a' p-18b Piezometers
P-18C, P-i8d p-i9a, P-l9b
._— GROUND SURFACE p.-\QC] P-19d
. . „;> 20 m SILTY SAND (K,«SXIO
20
18
12
10
8
10
. I .
Mil
zo
HORIZONTAL SCALE - METERS
10m
LEGEND
GROUND WATER EOUIPOTENTiAL
Q PIEZOMETER LOCATION
SCREENED SECTION
I'.V.'.Vj POTENTIALLY TRANSM'SSIVE LAYERS
HEAD ELEVATION AT CENTER OF SCREENS
FLOW LINE
Figure 6-10. Example flow net construction: Three layers with downward flow (Sara, 1994).
characterization because surface runoff controls will be to control surface runoff, then the topographic map and
the only routinely required engineered features. The site
topographic map will provide most of the information
required. If construction of sediment ponds is required
geologic cross sections showing depth of unconsoli-
dated material are required to identify areas of suitable
soil material for the impoundment. U.S. EPA (1986a),
86
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U.S. EPA (1988a), and U.S. EPA (1993d) should be
consulted for guidance when sewage sludge monofills
or dedicated surface disposal sites require construction
of liners and leachate collections systems and dikes or
embankments.
6,5.3 Special Site Conditions
The initial site selection process (Chapter 4) should
have eliminated sites from consideration where unfavor-
able site conditions (e.g., floodplains, wetlands, or un-
stable geology or soils), would make a site unsuitable.
If all possible sites are problematic in one way or an-
other, field investigations should have focused on
accurate delineation of problematic areas. Analysis and
interpretation of information obtained by these investi-
gations should focus on identification of the site or sites
where impacts of disposal or mitigation costs are mini-
mized. In the case of siting within floodplains, the mini-
mal disturbance of the hydrologic regime of the floodplain
must be demonstrated, as discussed in Section 6.4.5. If
wetlands must be disturbed, the unavailability of a
less-damaging alternative must be demonstrated. If site
stability is a concern, engineering cross-section and
design calculations should demonstrate adequate
safety factors based on site geotechnical characteristics
and reasonable design assumptions:
6.5.4 Computer Modeling
Numerous computer models have potential value for
assessing the possibility of environmental impacts from
surface disposal of sewage sludge and for designing
systems for minimizing impacts. This section identifies
relatively simple computer models that have been iden-
tified by U.S. EPA as being appropriate for use in as-
sessment and design of surface disposal sites, where
simplifying assumptions are appropriate. These include:
• The Hydrologic Evaluation of Landfill Performance
(HELP) model (see discussion on HELP model in
Chapter 7) is a water budget model for evaluating the
quantity of leachate generation.
• The VADOFT module of the Risk of Unsatu-
rated/Saturated Transport and Transformation of
Chemical Concentrations (RUSTIC) model (U.S.
EPA, 1989a and 1989b), a vadose zone chemical
transport model and AT123D (Yeh, 1981), a saturated
zone chemical transport model, were used by U.S.
EPA for the risk assessment modeling that developed
the Section 503 sludge pollutant limits.
• EPA's Multimedia Exposure Assessment Model
(MULTIMED) is intended to be used at surface dis-
posal sites where fate and transport modeling is re-
quired to demonstrate that performance criteria can
be met, provided that the site allows use of certain
simplifying assumptions (U.S. EPA, 1993d). MUL-
TIMED contains modules that estimate pollutant re-
leases to air, soil, ground water, and surface water.
U.S. EPA (1993a) and U.S. EPA (1992) provide docu-
mentation and guidance on how to use the model.
All of the above models use arithmetic or analytical
solutions that assume relatively simple hydrologic sys-
tems (e.g., as isotropic, homogeneous unsaturated, and
saturated zones), and only should be used if site condi-
tions justify making simplifying assumptions. If they are
not justified, then more sophisticated numerical com-
puter models should be used. Appendix D in U.S. EPA
(1993a) provides information on 17 commonly used
vadose zone flow and transport models. Recommended
major EPA documents that provide information on selec-
tion and use of subsurface flow and transport modeling
include: U.S. EPA (1985), U.S. EPA (1988b), and U.S.
EPA (1993f). U.S. EPA (1993b) provides a detailed re-
view of leachate generation and migration models.
6.6 References
1. American Society for Testing and Materials (ASTM). 1994. Draft
standard guide to site characterization for environmental pur-
poses. Philadelphia, PA: ASTM.
2. Boulding, J.R. 1994. Description and sampling of contaminated
soils: Afield guide, 2nd ed. Chelsea, Ml: Lewis Publishers.
3. Bureau of Reclamation. 1990. Earth Manual, 3rd ed, Part 2. U.S.
Department of the Interior, Bureau of Reclamation, Denver, CO.
[Part 1 consists of a 1990 reprint of the first 3 chapters of the
1974 2nd edition.]
4. Bureau of Reclamation. 1989. Engineering geology field manual.
U.S. Department of the Interior, Bureau of Reclamation, Denver, CO.
5. Cedergren, H.R. 1989. Seepage, drainage, and flow nets, 3rd
ed. New York, NY: John Wiley & Sons.
6. Corps of Engineers (COE). 1982. HEC-1, HEC-2, HEC-5, HEC-6
computer programs. Davis, CA: U.S. COE Hydrologic Engineer-
ing Center.
7. Corps of Engineers (COE). 1987. Wetlands delineation manual. Tech-
nical report Y-87-1. Vicksburg, MS: Waterways Experiment Station.
8. Dodd, K., H.K. Fuller, and P.P. Clarke, eds. 1989. Guide to ob-
taining USGS information. U.S. Geplogical Survey Circular 900.
9. Federal Interagency Committee for Wetland Delineation. 1989.
Federal manual for identifying and delineating jurisdictional wet-
lands. Cooperative Technical Publication, U.S. Army Corps of
Engineers, U.S. Environmental Protection Agency, U.S. Fish and
Wildlife Service, and U.S. Department of Agriculture Soil Conser-
vation Service, Washington, DC.
10. Gale Research Company. 1985. Climates of the states: National
Oceanic and Atmospheric Administration narrative summaries,
tables, and maps for each state, with overview of state climatolo-
gist programs, 3rd ed. Detroit, Ml: Gale Research Company.
11. Giefer, G.J., and O.K. Todd, eds. 1976. Water publications of state
agencies, first supplement, 1971-1974. Syosett, NY: Water Infor-
mation Center.
12. Giefer, G.J., and O.K. Todd, eds. 1972. Water publications of state
agencies. Syosett, NY: Water Information Center.
87
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13. Grawiewska, A., ed. 1969. KWIC index of rock mechanics litera-
ture published before 1969. New York, NY: American Institute of
Mining. Metallurgical, and Petroleum Engineering.
14. Hanna, T.H. 1985. Reid instrumentation in geotechnical engi-
neering. Ciausthal, Germany: Trans Tech Publications.
15. Hathaway, A.W. 1988. Manual on subsurface investigations.
Washington, DC: American Association of State Highway and
Transportation Officials.
16. Hatch, W.L. 1988. Selective guide to climatic data sources. Key
to meteorological records documentation no. 4.11. Asheville,
NC:NOAA National Climate Data Center.
17. Hvorslev, M.J. 1949. Subsurface exploration and sampling of
soils. New York, NY: Engineering Foundation.
18. Hydrology Subcommittee. 1982. Guidelines for determining flood
flow frequency. Bulletin #17B. Reston, VA: Interagency Advisory
Committee on Water Data, USGS Office of Data Coordination.
19. Jenkins, J.P., and E.T. Brown, eds. 1979. KWIC index of rock
mechanics literature, part 2, 1969-1976. New York, NY: Per-
gamon Press.
20. Kaplan, S.R. 1965. A guide to information sources in mining, min-
erals, and geosciences. New York, NY: Interscience Publishers.
21. Lyon, J.G. 1993. Practical handbook for wetland identification and
delineation. Boca Raton, FL: Lewis Publishers.
22. Makower, J., ed. 1992. The map catalog, 2nd ed. New York, NY:
Random House.
23. Mausbach, M.J. 1994. Classification of wetland soil for wetland
identification. Soil Surv. Horiz. 35(1):17-25.
24. National Technical Committee for Hydric Soils. 1991. Hydric soils
of the United States. Misc. Publ. 1491. Washington, DC: U.S.
Department of Agriculture, Soil Conservation Service.
25. Nielsen, D.M., ed. 1991. Practical handbook of ground-water
monitoring. Chelsea, Ml: Lewis Publishers.
26. Phillips, J.D. 1990. A saturation-based model of relative wetness
for wetland identification. Water Resour. Bull. 26(2):333-342.
27. Sara, M.N. 1994. Standard handbook of site assessment for solid
and hazardous waste facilities. Boca Raton, FL: Lewis Publishers.
28. Soil Survey Staff. 1992. Keys to soil taxonomy, 5th ed. SMSS
technical monograph no. 19. Blacksburg, VA: Pocahontas Press.
29. U.S. Army Corps of Engineers (USAGE). 1984. Engineering and
design: Geotechnical investigation. Engineer manual EM 1110-1-
1804. Washington, DC: U.S. Army Corps of Engineers.
30. U.S. EPA. 1993a. MULTIMED, the multimedia exposure assess-
ment model for evaluating the land disposal of wastes: Model
theory. EPA/600/R-93/081 (NTIS PB93-186252).
31. U.S. EPA. 1993b. Leachate generation and migration at Subtitle
D facilities: A summary and review of processes and mathemati-
cal models. EPA/600/R-93/125 (NTIS PB93-217778).
32. U.S. EPA. 1993c. Subsurface field characterization and monitor-
ing techniques: A desk reference guide, Vol. I. Solids and ground
water. EPA/625/R-93/003a; Vol. II. The vadose zone, field screen-
ing, and analytical methods. EPA/625/R-93/003b.
33. U.S. EPA. 1993d. Solid waste disposal facility criteria: Technical
manual. EPA/530-R-93-017 (NTIS PB94-100450).
34. U.S. EPA. 1993e. RCRA ground-water monitoring: Draft technical
guidance. EPA/530/R-93/001 (NTIS PB93-139350).
35. U.S. EPA. 1993f. Compilation of ground-water models.
EPA/600/R-93/118 (NTIS PB93-209401).
36. U.S. EPA. 1992. A Subtitle D landfill application manual for the
multimedia exposure assessment model (MULTIMED).
EPA/600/R-93/082 (NTIS PB93-185536).
37. U.S. EPA. 1991 a. Description and sampling of contaminated soils:
Afield pocket guide. EPA/625/2-91/002. Available from CERI.
38. U.S. EPA. 1991b. Delineation of wellhead protection areas in
fractured rocks. EPA/570/9-91/009.
39. U.S. EPA. 1991c. Site characterization for subsurface remedia-
tion. EPA/625/4-91/026.
40. U.S. EPA. 1990a. Proximity of sanitary landfills to wetlands and
deepwater habitats: An evaluation and comparison of 1,153 sani-
tary landfills in 11 states. EPA/600/4-90/012 (NTIS PB90-216524).
41. U.S. EPA. 1990b. Proximity of New York sanitary landfills to wet-
lands and deepwater habitats. EPA/600/4-89/046 (NTIS PB90-
155649).
42. U.S. EPA. 1990c. Water quality standards for wetlands: National
guidance. EPA/440/S-90/011.
43. U.S. EPA. 1989a. Risk of unsaturated/saturated transport and
transformation of chemical concentrations (RUSTIC), Vol. 1. The-
ory and code verification. EPA/600/3-89/048a.
44. U.S. EPA. 1989b. Risk of unsaturated/saturated transport and
transformation of chemical concentrations (RUSTIC), Vol. 2.
User's guide. EPA/600/3-89/048b.
45. U.S. EPA. 1988a. Guide to technical resources for the design of
land disposal facilities. EPA/625/6-88/018.
46. U.S. EPA. 1988b. Selection criteria for mathematical models used
in exposure assessments: Ground-water models. EPA 600/8-
88/075 (NTIS PB88-248752).
47. U.S. EPA. 1987. Technology briefs: Data requirements for select-
ing remedial action technology. EPA/600/2-87/001.
48. U.S. EPA. 1986a. Design, construction, and evaluation of clay
liners for waste management facilities. Draft technical guidance
document. EPA/530-SW-86-007F (NTIS PB89-181937).
49. U.S. EPA. 1986b. Criteria for identifying areas of vulnerable hy-
drogeblogy under the Resource Conservation and Recovery Act,
Appendix B. Ground-water flow net/flow line construction and
analysis, interim final. EPA/530/SW-86/022B (NTIS PB86-224979).
50. U.S. EPA. 1985. Modeling remedial actions at uncontrolled haz-
ardous waste sites. EPA 540/2-85/001 (NTIS PB85-211357).
51. U.S. Fish and Wildlife Service (USFWS). 1984. An overview of
major wetland functions and values. FWS/OBS-84/18.
52. U.S. Geological Survey. 1978. Preliminary young fault maps. Mis-
cellaneous field investigations MF-916.
53. U.S. Naval Facilities Engineering Command. 1982. Soil mechanics
design manual, Vol. 7.1. NAVFAC DM-7.1, Department of the Navy.
54. Vepraskas, M.J. 1992. Redoximorphic features for identifying
aquatic conditions. North Carolina Agricultural Research Service
technical bulletin 301. Department of Agricultural Communica-
tions, North Carolina State University, Raleigh, NC.
55. Ward, D.C. 1972. Geological reference sources: A subject and
regional bibliography of publications and maps in the geological
sciences. Metuchen, NY: Scarecrow Press.
56. Yeh, G.T. 1981. AT123D: Analytical transient one-, two-, and
three-dimensional simulation of waste transport in the aquifer
system. Environmental Sciences Division Publ. No. 1439. Oak
Ridge, TN: Oak Ridge National Laboratory.
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Chapter 7
Design
7.1 Purpose and Scope
The objective of a surface disposal site design is to
direct and guide the construction and ongoing operation
of the disposal site. A design should ensure:
• Compliance with pertinent regulatory requirements.
• Adequate protection of public health and the environment.
• Cost-efficient utilization of site manpower, equipment,
and storage volume.
A design package (consisting of all design documents)
should be prepared to provide a record of the site de-
sign. These may consist of drawings, specifications, and
reports.
The purpose of this chapter is to provide guidance on
the design of a surface disposal site. The organization
of specific topics addressed in this chapter is outlined in
Figure 7-1.
7.2 Regulatory Requirements
7.2.1 Part 503
Many types of active sewage sludge units (monofills,
dedicated surface disposal sites, piles and mounds, and
impoundments) are covered by the Part 503 Subpart C
regulation. The Part 503 regulation includes manage-
ment practices that must be followed when sewage
sludge is placed on an active sewage sludge unit. These
management practices help protect human health and
the environment from the reasonable anticipated ad-
verse effects of pollutants in sewage sludge. Several of
the management practices required under Subpart C
influence the design of active sewage sludge units.
Management practices influencing the design of these
units are summarized as follows (for more detail, see
U.S. EPA, 1994):
• Runoff from an active sewage sludge unit must be
collected and disposed of properly. Runoff collection
systems must be capable of handling a 25-year, 24-
hour storm event.
• When an active sewage sludge unit has a liner,
leachate must be collected and disposed of properly.
• When an active sewage sludge unit is covered daily,
Concentrations of methane gas must be monitored in
air in any structure within the site and in the air at
the property line of the surface disposal site.
• Sewage sludge placed in an active sewage sludge
unit must not contaminate an aquifer.
Another management practice required under Subpart
C requires the owner/operator of surface disposal sites
to restrict public access. Management practices influ-
encing the siting and end uses of active sewage sludge
units are discussed in Chapters 4 and 10, respectively.
Two of the management practices listed above refer to
active sewage sludge units with liners and leachate
collection systems and to units with covers.
• A liner is a layer of relatively impervious soil, such as
clay, or a synthetic material that covers the bottom of
an active sewage sludge unit with a hydraulic con-
ductivity of 1 x 10"7 cm/s or less. The liner prevents
the downward movement of liquid in the active sew-
age sludge unit from seeping into the ground water
below.
• A leachate collection system is a system or device
installed immediately above a liner,that collects and
removes leachate (liquid waste from rainfall that
seeps through the contents of the active sewage
sludge unit).
• A cover is soil or other material placed over the sew-
age sludge.
Sewage sludge placed on an active sewage sludge unit
with a liner and leachate collection system does not
have to meet pollutant limits, based on the assumption
that those systems prevent pollutants from migrating to
the ground water.
Sewage sludge placed on an active sewage sludge unit
without a liner and leachate collection system must meet
the pollutant limits for arsenic, chromium, and nickel
established under the Part 503 regulation. There are two
options for the pollutant limits (U.S. EPA, 1994):
• The first option is to make sure that the levels of
arsenic, chromium, and nickel are not above the lev-
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Section 7.2: Regulatory Requirements
Section 7.3: Permitting Requirements
_L
I Section 7.4: Design Methodology and Data Compilation
Section 7.5: Design for Monofills,
Impoundments, and Piles and Mounds
Foundation Design
MonofiH
Surface
Impoundments
and Lagoons
Piles!
and
Mounds
Slope and Stability Analyses
JL
Uner Systems
I
Leachate Collection Systems
Section 7.6: Codisposal
Design
Sludge/Solid Waste Mixture
Daily Cover Material
Sludge as Final Cover
Section 7.7: Dedicated Surface
Disposal
Natural Liner or Compliance
with Pollutant Limits
_L
No Contamination of Aquffiers
Land Area Needs
Proximity to Community
Infrastructure
Climate Considerations
Beneficial DSD Sites
Section 7.8: Environmental Safeguards
Leachate Controls
Run-on/Runoff Controls
'
Explosive Gases Controls
Section 7.9: Other Design Features
Access
Soil Availability
—
Special Working
Areas
—
Building and
Structures
—
Utilities [—
Lighting
-1 Wash Rack
Figure 7-1. Organization of Chapter 7, Design.
els listed in Table 3-6, which are based on the dis-
tance between the active sewage sludge unit bound-
ary and the property line of the surface disposal site.
• The second option is to meet the site-specific pollut-
ant limits for arsenic, chromium, and nickel, if site-
specific limits have been set by the permitting
authority.
(See Chapter 3 for more information on pollutant limits
for sewage sludge placed in surface disposal sites.)
7.2.1.1 Collection of Runoff
Runoff is rainwater or other liquid that drains over the
land and runs off of the land surface. Runoff from a
surface disposal site might be contaminated with sew-
age sludge or sewage sludge constituents. Runoff from
an active sewage sludge unit must be collected and
disposed of according to permit requirements of the
National Pollutant Discharge Elimination System
(NPDES) and any other applicable requirements. Under
the requirements of the Part 503 rule the runoff collec-
tion system of an active sewage sludge unit must have
the capacity to handle runoff from a 24-hour, 25-year
storm event (a storm that is likely to occur once in 25
years for a 24-hour period). This requirement helps
ensure that runoff (which may contain pollutants) from
an active sewage sludge unit site is not released into the
environment. The peak flow of water and the total runoff
volume of water during the 24-hour, 25-year storm must
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be calculated to properly size stormwater controls that
will be adequate to collect runoff from this storm (U.S.
EPA, 1994). (See Section 7.8.2 for design information
on runoff collection systems.)
7.2.1.2 Collection of Leachate
Leachate is fluid from excess moisture in sewage sludge
or from rainwater percolating down through the active
sewage sludge unit from the land surface. Depending
on the pollutant content of the sewage.sludge, leachate
may contain substances such,as metals or organic
chemicals. If an active sewage sludge unit has a liner
and leachate collection system, two management prac-
tices in the Part 503 regulation apply (U.S. EPA, 1994).
The first management practice requires that the
leachate collection system be operated and maintained
according to design requirements and engineering rec-
ommendations. The owner/operator of the surface dis-
posal site is responsible for ensuring that the system is
always operating according to design specifications and
is properly and routinely maintained (e.g., pumps are
periodically cleaned and serviced; the system is peri-
odically inspected to detect clogs and flushed to remove
deposited solids).
The second management practice requires that leachate
be collected and disposed of according to applicable
requirements. Leachate should be collected and
pumped out by a system placed immediately above a
liner. If leachate is discharged to surface water as a point'
source, then an NPDES permit is required. Otherwise,
leachate may be irrigated on land adjacent to the active
sewage sludge unit or discharged to a publicly owned
treatment works (POTWs). It is recommended that the
leachate be tested to determine whether some kind of
treatment is appropriate before being disposed of.
Both management practices must be followed while the
unit is active and for 3 years after the unit closes or for
a longer period if required by the permitting authority.
These management practices help prevent pollutants in
sewage sludge placed on an active sewage sludge unit
from being released into the environment. For example,
if leachate was not collected regularly, or if the leachate
collection system was not operated and maintained
properly, then the liner could be damaged by the weight
of the leachate pressing against it, and the leachate
could leak into the environment. Management practices
concerning the collection of leachate only apply to active
sewage sludge units with a liner. The Part 503 rule
regulates active sewage sludge units without liners and
leachate collection systems through the pollutant limits
discussed in Chapter 3 and through other management
practices in the regulation. (See Sections 7.5.6 and
7.5.7 respectively for design information on liners and
leachate collection systems.)
7.2.1.3 Limitations on Methane Gas
Concentrations
The Part 503 regulation contains a management prac-
tice that limits concentrations of methane gas in air
because of its explosive potential. Methane, an odorless
and highly combustible gas, is generated at an active
sewage sludge unit when sewage sludge is covered by
soil or other material (e.g., geomembranes), either daily
or at closure. The gas can migrate and be released into
the environment. To protect site personnel and the pub-
lic from risks of explosions, methane gas must be moni-
tored continuously within any structure;on the site and
at the property line of the surface disposal site. Air at
surface disposal sites where active sewage sludge units
are covered (either daily or at closure) must be moni-
tored continuously for methane gas; when active sew-
age sludge units are not covered, air does not have to
be monitored continuously for methane gas (U.S. EPA,
1994).
This management practice limits the amount of methane
gas in air in both active and closed sewage sludge units.
When a cover is placed on an active sewage sludge unit,
the methane gas concentration in air in any structure
within the property line of a surface disposal site must
be less than 25% of the lower explosive limit (LEL). The
LEL is the lowest percentage (by volume) of methane
gas in air that supports a flame under certain conditions
. (at 25°C and atmospheric pressure). For methane, the
LEL is 5%. Therefore, if 5% of the LEL is 50,000 ppm
methane, then air in any structure within the property
line must not exceed 12,500 ppm methane (U.S. EPA,
1994).
A methane gas monitoring device must be placed in
such a way that air inside any structure on the property
is continuously measured for methane gas and the
measurement can be read by any individual before en-
tering the structure. (The act of entering the building
could create enough of a spark to ignite explosive levels
of methane gas.)
For air at the property line of a'surface disposal site with
a covered sewage sludge unit, the limit for methane gas
concentration is the LEL (i.e., 5%). In some cases, the
permitting authority may determine that a methane gas
monitoring device at one downwind location on the prop-
erty line is adequate to meet this requirement because
the wind patterns are consistent. In other cases, where
wind conditions at the site are highly variable, more
than one device may be necessary to provide adequate
protection.
Methane gas concentrations must be monitored at all
times when an active sewage sludge unit is covered
daily and for 3 years after the last active sewage sludge
unit closes if a final cover is placed on the active sewage
sludge unit. If unstabilized sewage sludge is placed on
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sn active sewage sludge unit, the permitting authority
may require air to be monitored for methane gas for
longer than 3 years after closure because of the higher
potential for methane gas generation with unstabilized
sludge (U.S. EPA, 1994).
Methane monitoring devices allow the user to read the
level of methane as a percent of the LEL. Some can be
equipped with alarms, which may be desirable in struc-
tures with a higher potential for collecting methane gas.
Various methods (e.g., venting systems, positive or
negative air pressure systems) are available to control
methane gas concentrations if they exceed the limits.
(See Section 7.8.3 for information on explosive gases
control.)
7.2.1.4 Restriction of Public Access
Public access to a surface disposal site must be re-
stricted while the site contains an active sewage sludge
unit and for 3 years after the last active sewage sludge
unit closes (U.S. EPA, 1994). This management practice
helps to minimize public contact with any pollutants,
including pathogens, that may be present at surface
disposal sites. It also keeps the public away from an
area with the potential for methane gas explosions, as
discussed above. (See Section 7.9.1 for design informa-
tion on access restrictions.)
7.2.1.5 Protection of Ground Water
This management practice states that sewage sludge
placed in an active sewage sludge unit must not con-
taminate an aquifer. "Contaminate an aquifer" in this
instance means to introduce a substance that can cause
the level of nitrate in ground water to increase above a
certain amount. This management practice also re-
quires that proof be obtained that ground water is not
contaminated. This proof must be either (1) the results
of a ground-water monitoring program developed by a
qualified ground-water scientist, or (2) certification by a
ground-water scientist that ground water will not be
contaminated by the placement of sewage sludge on an
active sewage sludge unit.
The certification option usually is obtainable only if the
active sewage sludge unit has a liner and leachate
collection system. It is generally infeasible for a ground-
water scientist to certify that ground water will not be
contaminated in the absence of a liner unless ground
water is very deep and there is a natural clay layer or
unless the amount of material placed on the site is quite
low. (See Chapter 4 for more information on the protec-
tion of ground water at surface disposal sites.)
7.2.2 Part 258
EPA's Solid Waste Disposal Facility Criteria, 40 CFR
Part 258, regulate the design of municipal solid waste
(MSW) landfill units, including codisposal landfills. Sew-
age sludge placed in an MSW landfill must:
• Pass the paint filter liquids test (i.e., does not contain
free liquids).
• Not be a hazardous waste or PCB waste.
These requirements are discussed in Section 3.4.3. In
addition, the treatment works must ensure that the
sludge goes to a state-permitted landfill. Codisposal is
discussed in more detail in Section 7.6, Design for
Codisposal With Solid Waste.
7.2.3 State Rules Applicable to the Disposal
of Sewage Sludge
Part 503 does not replace any existing state regulations;
rather, it sets minimum national standards for the use or
disposal of sewage sludge. It is important to note that
persons disposing of sewage sludge are subject to state
and possibly local regulations in addition to federal regu-
lations. Furthermore, these state and other regulations
may be more stringent than the Part 503 rule, may
define sewage sludge differently, or may regulate certain
types of sewage sludge more stringently than does the
Part 503 rule. In addition, some states have established
requirements for their MSW landfills, including restric-
tions on codisposal, that are more stringent than on the
federal requirements. (For example, some states have
set loading limits for sludge at MSW landfills.) In all
cases, persons wishing to use or dispose of sewage
sludge must meet all applicable federal and state re-
quirements.
For information on specific state sewage sludge regula-
tions, the reader should consult the appropriate state
sewage sludge permitting authority, or state septage
coordinator. EPA regional sewage sludge and septage
coordinators are listed in Appendix B.
States can change their regulations to meet the mini-
mum federal standards. EPA will be working with states
to encourage them to gain approval for administering the
Part 503 rule. States can apply to EPA for approval of
their sewage sludge program at any time, but they are
under no obligation to do so. See Chapter 1 for more
information on the relationship of the federal require-
ments to state requirements.
7.3 Permitting Requirements
Many regulatory and approving agencies require per-
mits before a sewage sludge unit can be constructed or
operated. Accordingly, all pertinent agencies should be
contacted early in the design phase to: identify regula-
tions impacting on the prospective sewage sludge dis-
posal site; determine the extent, detail, and format of the
application; and, obtain any permit application forms.
Once this information has been collected, the design
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can proceed in a more efficient manner toward the goal
of receiving the necessary permits.
Before proceeding to the final design it is advisable to
recontact regulatory agencies who were contacted dur-
ing the site selection process and others to obtain all of
their requirements and procedures for permit application
submittals. This also will provide an opportunity to dis-
cuss design concepts, get questions answered, and
determine any special or new requirements. Mainte-
nance of close liaison with federal, state, and local
regulatory officials throughout the design effort is nor-
mally helpful in securing a permit without excessive
redesigns.
Requirements and permits relevant to sewage sludge
surface disposal sites exist on the federal, state, and
local levels.
7.3.1 Federal Permits
Federal permits required for sewage sludge surface
disposal sites include:
• U.S. EPA Interim Sewage Sludge Application cover-
ing sewage sludge use or disposal standards re-
quired under Part 503. Appendix A outlines the type
of information that should be provided in this permit
application.
• National Pollutant Discharge Elimination System .
(NPDES) permit required for location of a sludge sur-
face disposal site in wetlands. It is also required for
any point source discharges from surface disposal sites.
• Army Corps of Engineers Permit (a dredge and fill
permit) required for the construction of any levee,
dike, or other type of containment structure to be
placed in the water at a surface disposal site located
in wetlands.
• Office of Endangered Species permit may be required
from the Fish and Wildlife Service, U.S. Department
of the Interior, for location of surface disposal sites in
critical habitats of endangered species.
7.3.1.1 Self-Implementing Nature of the Part 503
Rule
The Part 503 rule is self-implementing—thai is,
owner/operators of surface disposal sites must comply
with the Part 503 rule (including the compliance dates
listed in Table 1-2 in Chapter 1), even if they have not
been issued a permit covering sewage sludge surface
disposal requirements. Similarly, EPA (or an approved
state) can take enforcement actions directly against per-
sons who violate the Part 503 requirements.
7.3.1.2 Who Must Apply for a Permit?
All sewage sludge surface disposal site owner/operators
must apply for a permit covering sewage sludge disposal
standards (U.S. EPA, 1994). Appendix A lists the type of
information that should be provided in a permit application.
In most cases, Part 503 requirements will be incorpo-
rated over time into NPDES permits issued to POTWs
and other treatment works treating domestic sewage
(U.S. EPA, 1994). As dictated by the permitting priorities
of EPA Regions and approved states, "sludge-only" per-
mits covering applicable Part 503 requirements are
likely to be issued to non-NPDES facilities as well. A
permit applicant who has not received a response from
EPA should continue to comply with the applicable pro-
visions of the Part 503 rule.
Certain surface disposal sites with unique site condi-
tions may apply for site-specific pollutant limits. These
sites would be issued site-specific permits.
7.3.1.3 Who Issues the Permit?
At the time this document was published, the permitting
authority for Part 503"was EPA. Thus, owner/operators
of a surface disposal site must apply to EPA Regional
Offices, not the state, for a federal sewage sludge per-
mit. This will remain the case until the sewage sludge
management programs of individual states are approved
by EPA (see Section 1.3). When a state has an EPA-ap-
proved sewage sludge management program, the per-
mitting authority will be the state; for states without an
EPA-approved program, EPA will remain the permitting
authority. State laws regarding the use or disposal of
sewage sludge, including permit requirements, must be
complied with, even if the state program has not re-
ceived federal approval. For more information on per-
mits, contact the appropriate EPA regional sludge
coordinator (Appendix B).
7.3.2 State and Local Permits
State and local regulations and permits are highly vari-
able from jurisdiction to jurisdiction. State and local
regulatory agencies that require submittals might in-
clude:
• Solid waste management agencies
« Water quality control agencies
• Health departments
• Building departments
• Health departments
• Planning and/or zoning commissions
• Board of county commissioners
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In many jurisdictions more than one state or local
agency has authority over a surface disposal site. Also,
in some jurisdictions, one agency has control over mon-
ofills and dedicated surface disposal sites while another
agency has control over MSW landfills where sewage
sludge is codisposed.
Depending on the jurisdiction, one or more permits
might be required for a surface disposal site. Typical
permits on the state and local levels include:
• Solid waste management permit.
• Special use permit.
• Zone change certification.
* Sedimentation control permit for surface runoff into
water courses.
• Highway department permit for entrances on public
roads and increased traffic volumes.
• Construction permit for site preparation.
• Building permit to construct buildings on the site.
• Operation permit for ongoing surface disposal operation.
• Mining permit for excavations.
• Fugitive dust permit.
• Business permit for charging fees.
• Closure permit.
The reviewing agency may require the submittal of in-
formation on standard forms or in a prescribed format to
facilitate the review process. In any event, applicants
are responsible for the completeness and accuracy of
the application package. The completed application
package is then reviewed by the regulatory agency. The
time of the review period will vary depending on the
regulatory agency, the number of applications preceding
it, etc. After a permit is issued, it can be valid for various
durations, depending largely on the submittal of inspec-
tion/performance reports and the outcome of onsite in-
spections.
7.4 Design Methodology and Data
Compilation
Adherence to a carefully planned sequence of activities
to develop a design for a surface disposal site minimizes
project delays and expenditures. A checklist of design
activities is presented in Table 7-1. These activities are
listed generally in their order of performance; however,
in many cases separate tasks can and should be per-
formed concurrently or even out of the order shown.
Initial tasks in any design methodology consist of com-
piling existing information and generating new informa-
tion on sludge and site conditions. See Chapter 4, Siting,
and Chapter 6, Field Investigation for extensive informa-
tion on collecting existing and site-specific information
for use in the design phase.
A complete design package may include plans, specifi-
cations, a design report, cost estimate, and operator's
manual. Generally, the cost estimate and operator's
manual are prepared strictly for in-house uses, while
plans, specifications, and design reports are submitted
to regulatory agencies in the permit application. Plans
and specifications typically include:
• Topographical map showing existing site conditions.
The map should be of sufficient detail, with contour
intervals of no more than 5 ft (1.5 m) and a scale not
to exceed 1 in. = 200 ft (1 cm = 24 m).
• Soil map, drainage map, and ground-water or pie-
zometric contour map.
• Site plan locating active sewage sludge units and soil
stockpile areas as well as site buildings. A small-scale
version of a site plan has been included as Figure 7-2.
• Development plan showing initial excavated and final
completed contours in sludge filling areas for mon-
ofills or surface impoundments and lagoons.
• Elevations showing cross sections to illustrate phased
development of filling areas at several interim points.
• Construction details illustrating detailed construction
of site facilities.
• Completed site plan including final site landscaping,
appurtenances, and other improvements.
A design report typically includes:
• Site description including existing site size, topogra-
phy and slopes, surface water, utilities, roads, struc-
tures, land use, soils, ground water, bedrock, and
climatology.
• Design criteria including sludge types and volumes,
sludge transport methods, and fill or disposal area
design dimensions.
• Operational procedures including site preparation,
sludge unloading, sludge handling, sludge storage,
sludge disposal rates for dedicated surface disposal
(DSD) sites, and sludge covering as well as equip-
ment and personnel requirements.
• Information on environmental safeguards including
surface water runoff controls, liners and leachate col-
lection systems, gas controls, odor controls, and vec-
tor reduction controls.
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Table 7-1. Sewage Sludge Surface Disposal Site Design
Checklist
Step
Task
Step
Task
_ Determine sludge volumes and characteristics
• Existing
• Projected
Compile" existing and generate new site information
• Perform boundary and topographic survey
• Prepare base map of existing conditions on site and
near site
- Property boundaries
- Topography and slopes
- Surface water
- Utilities
- Roads
- Structures
- Land use
• Compile hydrogeological information and prepare
location map
- Soils (depth, texture, structure, bulk density,
porosity, permeability, moisture, ease of excavation,
stability, Ph, and cation exchange
- Bedrock (depth, type, presence of fractures,
location of surface outcrops)
- Ground water (average depth, seasonal
fluctuations, hydraulic gradient, and direction of
flow, rate of flow, quality, uses)
• Compile climatological data
- Precipitation
- Evaporation
- Temperature
- Number of freezing days
- Wind direction
• Identify regulations (federal, state, and local) and
design standards
- Requirements for sludge stabilization
- Sludge loading rates
- Frequency of cover
r Distances to residences, roads, and surface water
- Monitoring
- Roads
- Building codes
- Contents of application for permit
Design filling area
• Select disposal method based on:
- Sludge characteristics
- Site topography and slopes
- Site soils
Design filling area (continued)
- Site bedrock
- Site ground water
• Specify design dimensions
- Trench dimensions
- Area fill dimensions
- Surface impoundment and lagoon dimensions
- Area requirements for DSD
- Sludge fill depth
- Intermediate cover soil thickness
- Final cover soil thickness
• Specify operational features
- Use of bulking agent
- Type of bulking agent
- Bulking ratio
- Use of cover soil
- Method of cover application
- Need for imported soil
- Equipment requirements
- Personnel requirements
• Compute sludge and soil uses
- Sludge disposal rate
- Soil requirements
Design facilities
• Leachate controls
• Gas controls
• Surface water controls
• Access roads
• Special working areas
• Structures
•' Utilities
• Fencing
• Lighting
• Washracks
• Monitoring wells
• Landscaping
Prepare design package
• Develop preliminary location plan of fill areas
• Develop contour plans
- Excavation plans
- Completed fill plans
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Table 7-1. Sewage Sludge Surface Disposal Site Design
Checklist (continued)
Stop Task
5 Prepare design package (continued)
• Compute sludge storage volume, soil requirement
volumes, and site life
• Develop final location plan showing:
- Normal fill areas and disposal areas
- Special working areas
- Leachate controls
- Gas controls
- Surface water controls
- Access roads
- Structures
- Utilities
- Fencing
- Lighting
- Washracks
- Monitoring wells
- Landscaping
• Prepare elevation plans for monofills and surface
impoundments with cross sections of:
- Excavated fill
- Completed fill
- Phased development of fill at interim points
• Prepare construction details
- Leachate controls
- Gas controls
- Surface water controls
- Access roads
- Structures
- Monitoring wells
• Prepare cost estimate
• Prepare design report
• Submit application and obtain required permits
• Prepare operator's manual
7.5 Design for Monofills, Surface
Impoundments, and Piles and
Mounds
7.5.1 Foundation Design
The following discussion is geared primarily toward ac-
tive sewage sludge units that are lined and have
leachate collection systems; however, good engineering
practice requires that proper subsoil foundation design
of all surface disposal sites be adequately addressed
during the design phase.
Proper subsoil foundation design of an active sewage
sludge unit with a liner is critical because liner system
components, especially leachate collection pipes and
sumps, can be easily damaged by stresses caused by
foundation movement.
Good engineering guidance requires that foundations
must be capable of providing support to the liner as well
as resistance of pressure gradients above and below the
liner to prevent failure of the liner due to settlement,
compression, or uplift.
Foundations for monofills or surface impoundments and
lagoons should provide structurally stable subgrades for
the overlying components. The foundations also should
provide satisfactory contact with the overlying liner or
other system components. In addition, the foundation
should resist settlement, compression, and uplift result-
ing from internal or external pressures, thereby prevent-
ing distortion or rupture of overlying components (U.S.
EPA, 1988a).
7.5.1.1 Field (investigation
Adequate field investigations are necessary to ensure
that the foundation design is developed to accommo-
date expected site conditions. Field investigations are
designed to establish the in situ subsurface properties,
site hydrogeologic characteristics, and the area seismic
potential, all of which are critical to the design of a
surface disposal site. Subsurface exploration programs
are conducted to determine a site's in situ subsurface
properties, as well as its geology and hydrogeology. The
in situ subsurface properties and hydrogeologic charac-
teristics have a significant influence on the bearing ca-
pacity, settlement potential, slope stability, and uplift
potential for the site. The site's subsurface geology may
impact the settlement and seismic potential at the site
and exert an influence on the site's hydrogeology char-
acteristics. See Chapter 6 for a more extensive discus-
sion on field investigations and subsurface explorations
programs.
7.5.1.2 Foundation Description
Foundation design procedures are site specific and very
often are an iterative procedure. A typical preliminary
foundation description should include (U.S. EPA, 1988a):
• Geographic setting
• Geologic setting
• Ground-water conditions
• Soil and rock properties
• Surface-water drainage conditions
• Seismic conditions
• Basis of information
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LEGEND
— EXISTING CONTOURS
PROPERTY BOUNDARY
ROADS
I I I II I" RAILROAD
T TRANSMISSION LINE
STREAM
gf^ POND
S DWELLINGS
• PUBLIC BUILDINGS
• WELL
WOODS
DISPOSAL AREA BOUNDARY
GROUNDWATER MONITORING
POINT
SURFACE WATER MONITORING
POINT
SURFACE WATER DRAINAGE
SYSTEM
SILTATION BASIN
GAS CONTROL/VENTING
IVM OPERATIONAL FACILITIES
niMi/ma DISPOSAL TRENCHES
Figure 7-2. Typical site plan.
Site plans should include the active sewage sludge unit
locations within the site; the unit depths, configurations,
and dimensions; and whether the unit will be completed
below or above grade. It is particularly important that the
investigation borings, test pits, and other procedures
described in Chapter 6 be performed as near as possi-
ble to the active sewage sludge units, if not within their
boundaries. Some other critical elements of the founda-
tion design that need to be addressed prior to comple-
tion of the field investigation are the foundation design
alternatives, the foundation grade, the loads exerted by
the unit or the foundation, and the preliminary settlement
tolerances.
7.5.1.3 Foundation Design
The engineering analysis for foundations is based on
subsurface conditions; however, the results of such
analyses are based on loading conditions. To perform
the appropriate engineering analysis to demonstrate the
97
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loadings should be prepared, in addition to plans showing
the structure's shape and size, the expected waste char-
acteristics and volumes, and the foundation elevations.
Foundations are designed to (U.S. EPA, 1988a):
• Provide structural support and to control settlement
• Prevent bearing capacity failure
• Withstand hydrostatic pressures
These are all discussed below.
Settlement and Compression
The foundation should be capable of preventing failure
of the liner system due to settlement and compression.
Therefore, it is important that an analysis be carried out
estimating total and differential settlement/compression
expected due to the maximum design loadings. The
results of this analysis are then used to evaluate the
ability of the liner system as well as the leachate collec-
tion and recovery systems to maintain their integrity
under the expected stresses (U.S. EPA, 1988a).
A settlement analysis will provide an estimate of maxi-
mum settlement. This maximum settlement can be used
to aid in estimating the differential settlement and distor-
tion of an active sewage sludge unit. Allowable settle-
ment is typically expressed as a function of total
settlement, rather than differential settlement, because
the latter is much more difficult to predict; however, the
differential settlement is a more serious threat to the
integrity of the structure than total settlement (Lambe
and Whitman, 1969; Wahls, 1981).
Active sewage sludge unit design calculations should
include estimates of the expected settlement, even if it
is expected to be small. Small amounts of settlement,
even a few inches, can cause serious damage to
leachate collection piping or sumps.
Bearing Capacity
For active sewage sludge units, the major issue of con-
cern for foundations is differential settlement; however,
for structures such as leachate risers, an additional area
of concern is bearing capacity failure (U.S. EPA, 1987a).
The basic criterion for foundation design is that settle-
ment must not exceed some permissible value. This
value varies, dependent on the structure and the toler-
ance for movement without disruption of the unit's integ-
rity. To ensure that the basic criterion is met, the bearing
capacity of a soil, often termed its stability, is the ability
of the soil to carry a load without failure within the soil
mass. The load carrying capacity of soil varies not only
with its strength, but often with the magnitude and dis-
tribution of the load. The reference Sowers and Sowers
(1970) provides information regarding the evaluation of
bearing capacities and typical ranges of key parame-
ters. After the bearing capacity is determined, the settle-
ment under the expected load conditions should be
estimated and compared to the permissible value. The
foundation design should be such that the actual bearing
stress is less than the bearing capacity by an appropri-
ate factor of safety (U.S. EPA, 1987a; Winterkorn and
Fang, 1975; Lambe and Whitman, 1969).
Seepage and Hydrostatic Pressures
Foundations should be designed to control seepage and
hydrostatic pressures. Heterogeneities such as large
cracks, sand lenses, or sand seams in the foundation
soil offer pathways for leachate migration in the event of
a release through the liner and could cause piping fail-
ures. In addition, soft spots in the foundation soils due
to seepage can cause differential settlement possibly
causing cracks in the liner above and damaging any
leachate collection or detection system installed. Cracks
also can be caused by hydrostatic pressure where the
latter exceeds the confining pressure of the foundation
and liner (U.S. EPA, 1986b).
Solutions to these problems include various systems
that are available to lower the hydraulic head at the
active sewage sludge unit. These systems include
pumping wells, slurry walls, and trenching. Other meth-
ods to control foundation seepage include grouting
cracks and fissures in the foundation soil with bentonite
and designing compacted clay cut-off seals to be em-
placed in areas of the foundation where lenses or seams
of permeable soil occur (U.S. EPA, 1986b).
7.5.2 Monofill Design
Several monofills were identified and described in Chap-
ter 2, Surface Disposal Practices. These include:
• Sludge-only trench
- — Narrow trench
- Wide trench
• Sludge-only area fill
- Area fill mound
- Area fill layer
- Diked containment
Chapter 2 provides a detailed discussion on each of
these monofills, and Table 2-1 lists the most significant
features affecting monofill selection, which are:
• Sludge percent solids.
• Sludge characteristics (stabilized or unstabilized).
• Hydrogeology (deep or shallow ground water and
bedrock).
• Ground slopes.
98
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Having chosen a site (Chapter 4) and a monofill (Chap-
ter 2) appropriate to that site, a suitable design must be
established. Sections 7.5.2.1 and 7.5.2.2 discuss con-
siderations that are relevant to trench and area fills. In
addition, Chapter 14, Design Examples, provides an
illustration of how a monofill is selected for a given site.
7.5.2.1 Trench Designs
In a trench operation, sludge is placed entirely below the
original ground surface. Sludge is usually dumped di-
rectly into trenches from haul vehicles. Onsite equip-
ment is used only to excavate trenches and apply cover;
equipment does not usually come into contact with the
sludge.
Trenches have been further classified into narrow
trenches and wide trenches. If trenches are selected,
design of the filling area consists primarily of determin-
ing the following parameters:
• Excavation depth
• Spacing
• Width
• Length
• Orientation
• Sludge fill depth •
• Cover thickness
Table 7-2 outlines a methodology for determining each
of these parameters.
Trench spacing is perhaps the most important and yet
most difficult design parameter to determine. Trench
spacing is defined as the width of solid undisturbed
ground that is maintained between adjacent trenches.
Generally, trench spacing should be as small as possi-
ble to optimize land utilization rates; however, the trench
spacing must be sufficient to resist sidewall cave-in.
Failure of the trench sidewalls is a safety hazard and
reduces the volume of the trench available for disposal.
Factors to consider in determining trench spacing include:
• The weight of the excavating machinery.
• The bearing capacity of the soil (which is a factor of
soil cohesion, density, and compaction).
• Saturation level of the soil (which may be significantly
influenced by the moisture content of the sludge).
• The depth of the trench.
• Soil stockpiling and cover placement procedure.
A general rule of thumb to follow in establishing trench
spacing is that for every 1 ft (0.3 m) of trench depth,
there should be 1 to 1.5 ft (0.3 to 0.5 m) of space
between trenches. If large inter-trench spaces are not
practical, the problem of sidewall instability may be re-
lieved by utilizing one of the four trench sidewall vari-
ations shown in Figure 7-3. In any event, test cell
trenches should be used to determine the operational
feasibility of any trench design. Such tests should be
performed by excavating adjacent trenches to the speci-
fied depth, width, and spacing. A haul vehicle fully
loaded with sludge should then back up to the trench to
determine if the sidewall stability is sufficient.
Using the considerations included in Table 7-2, design
parameters can be determined for a variety of sludge
and site conditions. These considerations have been
employed to develop some alternative design scenarios
for trenches shown in Table 7-3. In some cases, sludge
Table 7-2. Design Considerations for Trenches
Design Parameter Determining Factor
Consideration
Excavation Depth
Depth to groundwater
Depth to bedrock
Soil Permeability
Cation exchange capacity of soil
Equipment limitations
Sidewall stability
Sufficient thickness of soil must be maintained between trench bottom and
groundwater or bedrock Required minimum separation varies from 2 to 5 ft.
Larger separations may be required for higher than normal soil permeabilities
or sludge loading rates.
Normal excavating equipment can excavate efficiently to depths of 10 ft.
Depths from 10 to 20 ft are less efficient operations for normal equipment;
larger equipment may be required. Depths over 20 ft are not usually possible.
Sidewall stability determines maximum depth of trench. If haul vehicles are
to dump sludge into trench from above, straight sidewall should be
employed. Tests should be performed at site with a loaded haul vehicle to
ensure that sidewall height as designed will not collapse under operating
conditions.
Spacing
Sidewall stability
Soil stockpiles
Vehicle access
Trench spacing is determined by sidewall stability. Greater trench spacing will
be required when additional sidewall stability is required. As a general rule,
1.0 to 1.5 ft of spacing should be allowed between trenches for every 1 ft of
trench depth.
Sufficient space should be maintained between trenches for placement of
trench soil stockpiled for cover as well as to allow access and free
movement by haul vehicles and operating equipment.
99
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Tablo 7-2. Design Considerations for Trenches (continued)
Design Parameter Determining Factor Consideration
Width
Sludge solids content
Equipment limitations
Equipment efficiencies
Length
Sludge solids content
Ground slopes
Widths of 2 to 3 ft for typical sludge with solids content from 15 to 20%.
Widths of more than 3 ft for typical sludge with solids content more than
20%. Certain sludge (e.g., polymer treated) may require higher solids
contents before these widths can apply.
Widths up to 10 ft for typical equipment (such as front end loader) based on
solid ground alongside trench. Widths up to 40 ft for some equipment (such
as a dragline) based on solid ground. Unlimited widths for cover applied by
equipment (such as bulldozers) which proceed out over sludge.
Equipment
Typical Widths
Trenching machine
Backhoe
Excavator
Track dozer
Track loader
Dragline
Scraper
2ft
2-6 ft
4-22 ft
>10ft
i10ft
;>40 ft
>20ft
If sludge solids are low and/or trench bottoms not level, trench should be
discontinued or dikes placed inside trench to contain sludge in one area and
prevent it from flowing over large area.
Orientation
Land availability
Ground slopes
Trenches should be parallel to optimize land utilization.
For low solids sludge, axis of each trench should be parallel to topographic
contours to maintain constant bottom elevation within each trench and
prevent sludge from flowing. With higher solids sludge, this requirement is
not necessary.
Sludge fill depth Trench width
Cover application method
Cover thickness Trench width
Cover application method
Trench width
2-3 ft
>3ft
>10ft
Trench width
2-3 ft
>3ft
>10ft
Cover application method
Land-based equipment
Land-based equipment
Sludge-based equipment
Cover application method
Land-based equipment
Land-based equipment
Sludge-based equipment
Minimum distance
from top
1-2 ft
3ft
4ft
Cover thickness
2-3 ft
3-4 ft
4-5 ft
TYPE I TYPE 2
Figure 7-3. Trench stdewall variations.
and site conditions may indicate that it is wholly appro-
priate to utilize one of these trench scenarios for appli-
cation to a real-world situation. Given the great variety
of sludge and site conditions and their combinations,
however, some adaptation of one of these scenarios will
TYPE 3
TYPE 4
be necessary in most cases. In any event, design pa-
rameters should not be merely extracted from these
tables; parameters should always be well-considered
and tested before full-scale application. An example of
a trench design (which utilizes these tables initially, fol-
100
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ids
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101
-------
lowed by engineering investigation and field testing) has
been included in Chapter 14, Design Examples.
Narrow Trench
The use of narrow trenches has grown considerably
despite high area requirements (U.S. EPA, 1986a). This
method has found much more acceptance than other
forms of monofilling in areas where siting of a conven-
tional MSW landfill or a wide-trench monofill would en-
counter community resistance (U.S. EPA, 1986a). One
of the very important advantages of narrow trench mon-
ofilling is that the time during which sludge is uncovered
can be reduced to minutes with subsequent minimal
likelihood of unpleasant odors.
Narrow trenches have widths less than 10 ft (3.0 m) and
usually receive sludge with solids contents as low as
15%. Excavation and cover application in narrow trench
operations is carried out via equipment operating on
solid ground alongside the trench. Illustrations of typical
narrow trench operations are included as Figures 7-4
and 7-5. See also Section 2.3.1.1 for detailed informa-
tion on narrow trenches. Sludge characteristics, site
conditions, and design criteria for narrow trenches are
summarized in Tables 2-1 and 2-2.
The method of sludge placement in a narrow trench is
dependent on the type of haul vehicle and on trench
sidewall stability. Usually trench sidewalls are suffi-
ciently stable and sludge may be dumped from the haul
vehicle directly into trenches. If sidewalls are not suffi-
ciently stable, however, the sludge may be delivered to
the trench in a chute-extension similar to that found on
concrete trucks or pumped in via portable pumps. In
some cases, particularly in wet weather, it may be nec-
essary to dump the sludge on solid ground near the
Figure 7-5. Cross section of typical wide trench operation.
trench and have onsite equipment push the sludge into
the trench.
Wide Trench
Wide trenches have widths greater than 10 ft (3.0 m)
and usually receive sludge with solids contents of 20%
and more. Excavation of wide trenches is usually carried
out using equipment that enters the trench. Cover appli-
cation may be carried out using equipment operating on
solid ground alongside the trench, but is usually accom-
plished with equipment that traverses the sludge
spreading a layer of cover soil before it. Illustrations of
typical wide trench operations are included as Figures
7-6 and 7-7. See also Section 2.3.1.2 for detailed infor-
mation on wide trenches. Sludge characteristics, site
conditions, and design criteria for wide trenches are
summarized in Tables 2-1 and 2-2.
Sludge may be placed in wide trenches by haul vehi-
cles, either:
Figure 7-4. Cross section of typical narrow trench operation.
102
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EXCAVATED
DEPTH
61
Figure 7-6. Cross section of typical wide trench operation.
Figure 7-7. Wide trench operation.
• Directly entering the trench and dumping sludge in 3
to 4 ft (0.9 to 1.2 m) high piles.
• Parked at the top of trench sidewalls and dumping
sludge into the trench.
For the first of these two cases, sludge should have a
solids content of 32% or more to ensure that the sludge
will not slump and can be maintained in piles. For the
second approach, sludge should have a solids content
less than 32% to ensure that it will flow evenly through-
out the trench and not accumulate at the dumping loca-
tion. Of course, when sludge is freeflowing, some
means will be needed to confine the sludge to specific
areas in a continuous trench. Dikes are often used for
this purpose as illustrated in Figure 7-8.
7.5.2.2 Area Fill Designs
In an area fill operation, sludge is usually placed entirely
above the original ground surface. The sludge as re-
ceived is usually mixed with soil to increase its effective
solids content and stability. Several consecutive lifts of
this sludge/soil mixture are usually then applied to the
filling area. Soil may be applied for interim cover in
addition to its usual application for final cover. Onsite
equipment .usually does come into contact with the
sludge while performing functions of mixing the sludge
with soil; transporting this mixture to the fill area; mound-
ing or layering this mixture; and spreading cover over
the mixture.
Area fills have been further classified into area fill
mounds, area fill layers, and diked containments. If one
of these landfilling methods has been selected, design
of the filling area may consist primarily of determining
the following parameters:
• Bulking ratio
• Cover application procedure
• Width (of diked containment)
• Depth of each lift
• Interim cover thickness
• Number of lifts
• Depth of total fill (or diked containment before final cover)
• Final cover thickness
Table 7-4 outlines a methodology for determining each
of these parameters.
Using the considerations included in Table 7-4, the de-
sign parameters can be determined for a variety of
sludge and site conditions. These considerations have
been employed to develop some alternative design sce-
narios for area fills that are included in Table 7-3. An
example of an area fill design (which utilizes these
tables initially, followed by investigation and testing) has
been included in Chapter 14, Design Examples.
103
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DEPTH
Figure 7-8. Cross section of wide trench with dikes.
Table 7-4. Design Considerations for Area Fills
Design Parameter
Consideration
Bulking Ratio
Cover Application
Procedure
Width
(of diked containment)
Depth of each (in
Method
Area fill mound
Area fill layer
Diked containment
Method
Area fill mound
Area fill layer
Diked containment
Cover Application
Procedure
Land-based equipment
Sludge-based equipment
Method
Area fill mound
Area fill layer
Diked containment
Solids Content
20-28%
28-32%
£32%
15-20%
20-28%
28-32%
> 32%
20-28%
28-32%
> 32%
Solids Content
> 20%
2. 15%
20-28%
> 28%
Equipment Used
Dragline
Track dozer
Sludge Solids
> 20%
15-20%
> 20%
20-28%
> 28%
Bulking Ration
2 soil:1 sludge
1 soil:1 sludge
0.5 soil:1 sludge
1 soil:1 sludge
0.5 soil:1 sludge
0.25 soil:1 sludge
Not required
0.5 soil:1 sludge
0.25 soil:1 sludge
Not required
Cover Application
Procedure
Sludge-based equipment
Sludge-based equipment
Land-based equipment
Sludge-based equipment
Width
<;40ft
Not limited
Lift Depth
6ft
1 ft
2-3 ft
4-6 ft
6-10 ft
104
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Table 7-4. Design Considerations for Area Fills (continued)
Consideration
Interim cover thickness
Number of lifts
Depth of total fill
(of diked containment
before final cover)
Final cover thickness
Method
Area fill mound
Area fill layer
Diked containment
Method
Area fill mound
Area fill layer
Diked containment
Cover Application Procedure
Land-based equipment
Sludge-based equipment
Method
Area fill mound
Area fill layer
Diked containment
Cover Application
Procedure
Sludge-based equipment
Sludge-based equipment
Land-based equipment
Sludge-based equipment
Sludge Solids Contents
20-28%
>28%
> 15%
> 20%
r
Cover Application
Procedure
Sludge-based equipment
Sludge-based"equipment
Land-based equipment
Sludge-based equipment
Interim Cover
Thickness
3ft
0.5-1 ft
1-2 ft
2-3 ft
No. of Lifts
1 maximum
3 maximum
1-3 typical
1-3 typical
Depth of Total Fill
No higher than 3 ft
below top of dikes
No higher than 4 ft
below top of dikes
Final Cover Thickness
1 ft
1 ft-
3-4 ft
4-5 ft
Area Fill Mound
At area fill mound operations, sludge/soil mixtures are
stacked into mounds approximately 6 ft (1.8 m) high.
Cover soil is applied atop each lift of mounds in a 3 ft
(0.9 m) thickness. The cover thickness may be in-
creased to 5 ft (1.5 m) if additional mounds are applied
atop the first lift. Illustrations of typical mound opera-
tions are included as Figures 7-9 and 7-10. See also
Section 2.3.2.1 for detailed information on area fill
mounds. Sludge characteristics, site conditions, and de-
sign criteria for area fill mounds are summarized in
Tables 2-1 and 2-2.
Sludge as received at the landfill is usually mixed with
a bulking agent. The bulking agent absorbs excess
moisture from the sludge and increases its workability.
The amount of soil needed to serve as an additional
bulking agent depends on the solids content of the
sludge. Generally the soil requirements shown in Table
7-4 may serve as a guideline. Fine sand appears to be
the most suitable bulking agent because it can most
easily absorb the excess moisture from the sludge.
Area Fill Layer
At area fill layer operations, sludge/soil mixtures are
spread evenly in layers from 0.5 to 3 ft (0.15 to 0.9 m)
thick. This layering usually continues for a number of
applications. Interim cover between consecutive layers
may be applied in 0.5 to 1 ft (0.15 to 0.3 m) thick
applications. Final cover should be at least 1 ft (0.3 m)
thick. An illustration of a typical area fill layer operation
is included as Figure 7-11. See also Section 2.3.2.2 for
detailed information on area fill layers. Sludge charac-
teristics, site conditions, and design criteria for area fill
layers are summarized in Tables 2-1 and 2-2.
Diked Containment
At diked containment operations, earthen dikes are con-
structed to form a containment area above the original
ground surface. Dikes can be of various heights, but
require side slopes of at least 2:1 and possibly 3:1. A15
ft (4.6 m) wide road, covered with gravel, should be
constructed atop the dikes. An illustration of a typical
diked containment operation is included as Figure 7-12.
See also Section 2.3.2.3 for detailed information on
105
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FINAL COVER
REMOVE FOR USE
AS SLUDGE BULKING
AGENT
FUTURE
DRAINAGE
DITCH
INTERMEDIATE COVER
<3' THICK)
LEACHATE CONTROL
Figure 7-9. Cross section of typical area fill mound operation.
SLUDGE/SOIL
MIXTURE
Figure 7-10. Area fill mound operation.
REMOVE FOR USE
AS SLUDGE BULKING
AGENT
INTERIM COVER
(0.5-I THICK).
LEACHATE COLLECTION
Figure 7-11. Cross section of typical area fill layer operation.
FUTURE
DRAINAGE
DITCH
SLUDGE/SOIL MIXTURE
(3' THICK)
106
-------
MIN. OF 15' OR AS REOUSRED
FOR CONSTRUCTION EQUIPMENT
EXTEND TO PREVENT
DISCHARGE ON SLOPE
FACE
3
UPPER SLUDGE LAYER
MIDDLE DRAINAGE BLANKET
Figure 7-12. Cross section of typical diked containment operation.
diked containment. Sludge characteristics, site condi-
tions, and design criteria for diked containments are
summarized in Tables 2-1 and 2-2.
Sludge may be either:
• Mixed with soil bulking for subsequent transport and
dumping into the containment area by onsite equip-
ment.
• Dumped directly into the containment area by haul
vehicles without bulking soil.
Large quantities of imported soil may be required to
meet soil requirements for dike construction and bulking
since diked containments are often constructed in high
ground-water areas. ' ,
Sludge is dumped into diked containments in lifts before
the application of interim cover. Often this interim cover
is a highly permeable drainage blanket that acts as a
leachate collection system for sludge moisture released
from the sludge lift above. Final cover should be of a
less-permeable nature and should be graded even with
the top of the dikes.
7.5.3 Surface Impoundment and Lagoon
Design
At aboveground surface impoundments, dikes are used
to contain the sewage sludge, and haul vehicles dump
sludge directly into the containment area from the sides
of the dikes. Design information for diked containment
can be found in Section 7.5.2.2.
Belowground surface impoundments or lagoons have
been widely used for treatment and storage of sludge.
The surface disposal provisions of the Part 503 rule do
not apply when sludge is treated in a lagoon (or other-
wise treated on the land) for what could be an indefinite
period. Figure 7-13 compares treatment lagoons and
storage/disposal lagoons. The surface disposal provi-
sions also do not apply to lagoons used for long-term
temporary storage of sludge ifthe storage is considered
part of the treatment process and if the facility's
owner/operator has a rationale or a plan for final use or
disposal of the sludge. If, however, the sludge generator
has no intention of ever removing the sludge from the
lagoon, the facility is considered a surface disposal site
and is subject to the Part 503 surface disposal require-
ments, including requirements for pollutant limits, clo-
sure, management practices, pathogen and vector
attraction reduction, monitoring, and recordkeeping and
reporting. Many states also have requirements for la-
goons. Check with your state for any specific state
requirements for designing lagoons.
Ground-water protection is a key concern with respect
to sludge lagoons, A minimum soil buffer of 4 ft is rec-
ommended between the bottom of a lagoon and the
seasonal annual high ground-water table. Liners and
leachate collection systems should be considered, de-
pending on sludge quality, distance to drinking water
wells, depth to ground water, ground-water flow direc-
tion and velocity, aquifer classification, and underlying
soil type and permeability (U.S. EPA, 1990).
Three types of lagoons are described below: facultative
sludge lagoons, anaerobic liquid sludge lagoons, and
sludge drying lagoons. If the dewatered sludge is peri-
odically removed from these lagoons, they are consid-
ered treatment lagoons, but if the sludge is never
removed, they are considered surface disposal facilities.
7.5.3.1 Facultative Sludge Lagoons
Facultative sludge lagoons (FSLs) are designed to
maintain an aerobic surface layer free of scum or mem-
brane-type film buildup. The aerobic layer is maintained
by keeping the annual organic loading to the lagoon at
or below a critical area loading rate and by using surface
mixers to provide agitation and mixing of the aerobic
surface layer. The aerobic surface layer of FSLs is usu-
ally from 1 to 3 ft (0.30 to 0.91 m) in depth and supports
a very dense population of between 50 x 103 and 6 x
106 organisms/mL of algae (usually Chorella). Dissolved
107
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a) Wastawater
Treatment
Lagoon
Settled Sludge •
Initial Treatment Lagoon Polishing Pond
Effluent
Settled Sludge
b) Sludge
Storage/
Disposal
Lagoon
Sludge Lagoon
Figure 7-13. Comparison of wastewater lagoon and sludge lagoon (U.S. EPA, 1990).
oxygen is supplied to this layer by algal photosynthesis,
by direct surface transfer from the atmosphere, and by
the surface mixers. The oxygen is used by the bacteria
in the aerobic degradation of colloidal and soluble or-
ganic matter in the digested sludge liquor, while the
digested sludge solids settle to the bottom of the basins
and continue their anaerobic decomposition. Sludge liq-
uor or supernatant is periodically returned to the plant's
liquid process stream.
The nutrient and carbon dioxide released in both the
aerobic and anaerobic degradation of the remaining
organic matter within the digested sludge are, in turn,
used by the algae in the cyclic-symbiotic relationship.
This vigorous relationship maintains the pH of the FSL
surface layer at between 7.5 and 8.5, which effectively
minimizes any hydrogen sulfide (H2S) release and is
believed to be a key to the successful operation of this
type of sludge storage process.
Facultative sludge lagoons must operate in conjunction
with anaerobic digesters (U.S. EPA, 1979). They cannot
function properly (without major environmental impacts)
when supplied with either unstabilized or aerobically
digested sludge (U.S. EPA, 1979). If the acid phase of
anaerobic stabilization becomes predominant, the la-
goons will give off an offensive odor. Figure 7-14 pro-
vides a schematic representation of the reactions in a
typical FSL.
Design Criteria
Design considerations for the FSLs include the area
loading rate, surface agitation requirements, dimen-
sional and layout limitations, and physical factors:
• Area Loading Rate. To maintain an aerobic top layer,
the annual organic loading rate to the FSL must be
at or below 20 Ib of volatile solids (VS) per 1,000 sq
ft per day (1.0 t VS/ha-d). Lagoons have been found
to be capable of receiving the equivalent of the daily
organic loading rate every second, third, or fourth day
without experiencing any upset. That is, lagoons have
assimilated up to four times normal daily loadings as
long as they have had 3 days of rest between load-
ings. Loadings as high as 40 Ib VS per 1,000 sq ft
per day (1.0 t VS/ha-d) have been successfully as-
similated for several months during the warm sum-
mer and fall. Experiments on small basins loaded to
failure indicate that peak loadings up to 90 Ib VS per
1,000 sq ft per day (4.4 t VS/ha-d) can be tolerated
during the summer and fall as long as they do not
occur for more than 1 week.
• Surface Agitation Requirements. Experiments on
FSLs that were continuously loaded at the standard
rate (1.0 t VS/ha-d) indicate FSLs cannot function in
an environmentally acceptable manner without daily
operation of surface agitation equipment. Observa-
tions indicate the brush-type mixer is required to
breakup the surface film that forms during the feeding
108
-------
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Figure 7-14. Schematic representation of an FSL (U.S. EPA, 1979),
of the lagoon. If this film is not dissipated, a major
source of oxygen transfer to the surface layer is elimi-
nated. FSLs with surface areas of from 4 to 7 acres
(1.6 to 2.8 ha) require the operation of two surface
mixers from 6 to 12 hr per day to successfully main-
tain scum-free surface conditions. All of the success-
ful installations to date have used brush-type floating
surface mixers to achieve the necessary surface agi-
tation. Two brush-type mixers with 8-ft-long (2.4-m)
rotors turning at approximately 70 rpm and driven by
15 hp (11.2 kW) motors are required for a 4 to 7 acre
(1.6 to 2.8 ha) lagoon. The mixers need to operate
12 hr per day. Lagoons of much less than 4 acres
(1.62 ha) should be able to achieve the same results
with two mixers with 6-ft (1.8-m) long rotors and 5-hp
(3.7 kW) motors. Operation time is expected to be
about the same number of hours per day. Brush-type
mixers have been used to limit the agitation to the
surface layer of the FSLs. So far this has been an
acceptable application; however, there is some ques-
tion as to their applicability for very cold climates.
Several submerged pump-type floating aerators have
been reviewed, and they could be adapted to provide
the necessary surface agitation if the brush-type
could not function under severe freezing conditions.
Two mixers are used per FSL to ensure maximum
scum breakup in those areas of the lagoon where the
prevailing wind deposits the daily loading of scum. The
agitation and mixing action of the two mixers located
at opposite ends or sides of the lagoon also act to
maintain equal distribution of the anaerobic solids.
Dimensional and Layout Limitations. The maximum
area for a single lagoon area is somewhat arbitrary
but is based on the most practical size for loading,
surface agitation, mixing (and, for treatment lagoons,
removal) requirements. Large, 4 to 7 acre (1.6-2.8
ha) individual lagoons would be applicable only to
plants with over 70 acres (28 ha) of FSLs. FSLs as
small as 150 ft (45.7 m) on a side have been operated
successfully. Lagoon depths can range from about
11.5 to 15,ft (3.5 to 4.7 m). If surface agitation must
be maintained by submerged pump type aerators, it
may be necessary to use the deepest lagoon possible
to ensure adequate separation between the aerobic zone
and the anaerobic settling zone of the FSL.
FSLs are usually best designed to have a long and
a short dimension, with the shortest dimension ori-
ented parallel to the direction of the maximum pre-
vailing wind. The longer side is made conducive to
109
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efficient dredge operation, while the short side's par-
allel orientation to the prevailing wind direction helps
to minimize wave erosion on the surrounding levees.
Figure 7-15a is a typical FSL layout, while Figure
7-15b is a typical FSL cross section.
When the area of FSLs exceeds 40 acres (16.2 ha),
the potential cumulative effect of large odor emission
areas to the vicinity must be considered. Figure 7-16
shows the layout for the 124 acres (50.2 ha) of FSLs
in Sacramento, California, that were sited on the ba-
sis of the least odor risk to surrounding areas. Bat-
teries of FSLs totaling 50 to 60 acres (20 to 24 ha)
are about the maximum size for most effectively re-
ducing the transport of odors.
Physical Considerations. Many of the detailed physi-
cal considerations applied to the final design of the
Sacramento FSLs are shown in Figures 7-15b and
7-16. Supernatant withdrawal is located upstream
from the prevailing winds to minimize scum buildup
in its vicinity. FSL supernatant will precipitate magne-
sium ammonia phosphate (struvite) on any rough sur-
face that is not completely submerged; it has also
been found to precipitate inside cavitating pumps.
This crystalline material can completely clog cast-iron
PREVAILING WIND DIRECTION
SUPERNATANT
OVERFLOW
AUTOMATIC
CONTROL VALVE
•SLUDGE REMOVAL
VALVES
DIGESTED SLUDGE\
LINE*
-DIGESTED SLUDGE
INLETS
SURFACE MIXER
SURFACE MIXER
SLUDGE
REMOVAL
DREDGE
ANCHOR
POSTS
(TYP)
BOTH
p
O ENDS
•'p
c
1C
Figure 7-15a. Typical FSL layout (U.S. EPA, 1979).
3'0" AEROBIC LAYER
12'0" ANAEROBIC 6" IMPERVIOUS
LAYER LAYER
DIGESTED SLUDGE
INLET
PROTECTION
ENGINEERED FILL
8" DIGESTED
SLUDGE LINE
SLOPE 3
1
-MINIMUM
2'S" COVER
-NATURAL
GRADE
1 ft - Q.3 m NOT TO SCALE
1 Jn - 2.5 cm
Figure 7-15b. Typical FSL cross section (U.S. EPA, 1979).
110
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MB I
iSlhliii! i
i
LAYOUT FOR 124 ACRES OF FSLs—SACRAMENTO }
REGIONAL WASTEWATER TREATMENT PLANT
Figure 7-16. Layout for 124 acres of FSLs: Sacramento Regional Wastewater Treatment Plant (U.S. EPA, 1979).
111
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fittings and pump valves when the surface goes
through a fill-and-draw cycle or when its operation
results in the presence of diffused air. The most prac-
tical approach to eliminating this problem has been
to use PVC piping throughout the FSL supernatant
process and to design the process for gravity return
to the plant influent, with a minimum of critical depth
conditions. If pumping is required, submerged slow-
speed nonclog centrifugal pumps with low suction
and discharge velocities (to minimize cavitation) will
be the most trouble free. All equipment that is not
PVC or another smooth non-metallic material should
be coated with a smooth, impervious surface.
Two digested sludge feed lines, each with its own auto-
matic valve, ensure adequate distribution of solids over
the whole volume of the FSL. Surface mixers are down-
stream of the prevailing winds. The harvested sludge
dredge hookup is centrally located. Lagoon dike slopes
are conservative—3 horizontal to 1 vertical—with ade-
quate rip-rap provided in the working zone of the surface
level. Sufficient freeboard is provided to protect against
any conceivable overtopping of the dikes. Digested
sludge feed pipelines are located directly below the
bottom of the lagoons, with the inlet surrounded by a
protective concrete surface. All piping within the basin is
out of the way of any future dredging operations.
Table 7-5 presents design criteria for the Sacramento,
California, facultative sludge lagoons.
7.5.3.2 Anaerobic Liquid Sludge Lagoons
An anaerobic lagoon is usually an open structure similar
to the facultative lagoon, but often with a greater depth
in relation to surface area (Lue-Hing et al., 1992). These
lagoons settle solids with higher specific gravity than
water and provide for sludge storage on the bottom.
Unlike the facultative lagoon, an aerobic surface layer is
Tablo 7-5. Design Criteria for Sludge Storage Basins:
Sacramento (California) Regional Wastewater
Treatment Plant (Lue-Hing et al., 1992)
Total number of sludge storage basins 20
Surface area—hectares (acres) 50.6 (125
Depth at normal operation—m (ft) 4.57 (15)
Solids loading rate— kg/m2/d (lbs/1000 ffrd) 0.0975 (20)
Stored solids concentration. % >6
Surface mixers for aeration 40
Barrier wall height, m (ft) 3.64 (12)
Supernatant return flow metering 3.154-17.0
90° V-notch weir, L/s (gpm) (50-270)
30.5 cm (12 in.) Parshall flume 8.77-175.3
L/s (MOD) 0.2-4.0)
not maintained and floatable material is not settled or
removed; thus, a thick scum layer can develop on the
lagoon surface. Sludge loading rates to anaerobic la-
goons are higher than the loading rates of facultative
lagoons (Lue-Hing et al., 1992). Figure 7-17 shows the
layout of four anaerobic lagoons at the Metropolitan
Sanitary District of Greater Chicago Prairie Plan land
reclamation project in Fulton County, Illinois.
Table 7-6 presents the advantages and limitations of
facultative sludge lagoons and anaerobic lagoons.
7.5.3.3 Sludge Drying Lagoons
Sludge drying lagoons consist of retaining walls that are
normally earthen dikes 2 to 4 ft (0.7 to 1.4 m) high. The
earthen dikes usually enclose a rectangular space with
a permeable surface. Appurtenant equipment includes
sludge feed lines and metering pumps, supernatant de-
cant lines, and some type of mechanical sludge removal
equipment, if sludge is to be removed. In areas where
permeable soils are unavailable, underdrains and asso-
ciated piping may be required.
Figure 7-18 shows a plan view of a sludge drying lagoon.
3 a TRANSFER I PUMP
54.9 AC , -K 3b
37.3 AC
HOLDING BASINS
t acn - 0.4(15 h*
Figure 7-17. Anaerobic liquid sludge lagoons, Prairie Plan land
reclamation project, the Metropolitan Sanitary Dis-
trict of Greater Chicago (U.S. EPA, 1979).
112
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Design Criteria
Proper design of sludge drying lagoons requires a con-
sideration of the following factors: climate, subsoil per-
meability, sludge characteristics, and lagoon depth and
area. A discussion of these factors follows.
• Climate. After dewatering by drainage and supernat-
ing, drying in a sludge lagoon depends primarily on
evaporation. Proper size of a lagoon, therefore, re-
quires climatic information concerning:
- Precipitation rate (annual and seasonal distribution).
Table 7-6. Advantages and Limitations of Faculative Sludge Lagoons and Anaerobic Lagoons (U.S. EPA, 1979)
Advantages
Limitations
Provides long-term storage with .
acceptable environmental impacts
(odor and groundwater contamination
risks are minimized) .
Continues anaerobic stabilization, with up
to 45 percent VS reduction in first year.
Decanting ability assures minimum solids
recycle with supernatant (usually less
than 500 mg/1) and maximum concentration
for storage and efficient harvesting
(>6 percent solids) starting with digested
sludge of <2 percent solids.
Long-term liquid storage is one of few
natural (no external energy input) means
of reducing pathogen content of sludges.
Energy and operational effort requirements
are very minimum.
Once established, buffering capacity is
almost impossible to upset.
Allows for all tributary digesters to
operate as primary complete-mix units
(one blending unit may be. required for
large installations).
Provides environmentally acceptable place
for disposal of digester contents during
periodic cleaning operations.
Sludge harvesting is completely independent
from sludge production.
Can only be used following anaerobic
stabilization. If acid phase of
digestion takes place in lagoons' they
will stink.
Large acreages require special odor .
mitigation measures.
Reauires large areas of land, for
example, 15 to 20 gross acres (6 ro
8 ha) for 10 MGD, (438 1/s) 200
gross acres (80 ha) for 136 MGD
(6,000 1) carbonaceous activated
sludge plants.
4. Must be protected from flooding.
5. Supernatant, will contain 300-600 mg/1
of TKN, mostly ammonia.
6. Magnesium ammonia phosphate (struvite)
deposition requires special supernat-
ant design.
@ DRAW - OFF BOX & TRUSS
-------
— Evaporation rate (annual average, range, and sea-
sonal fluctuations).
- Temperature extremes.
• Subsoil Permeability. The subsoil should have a mod-
erate permeability of 1.6 x 10"4 to 5.5 x 10'4 in. per
second (4.2 x 1CT4 to 1.4 x 10'3 cm/s).
• Sludge Characteristics. The type of sludge to be
placed in the lagoon can significantly affect the
amount and type of odor and vector problems that
can be produced. It is recommended that only an-
aerobically digested sludges be used in drying lagoons.
• Lagoon Depth and Area. The actual depth and area
requirements for sludge drying lagoons depend on
several faptors such as precipitation, evaporation,
type of sludge, volume and solids concentration. Sol-
ids loading criteria have been given as 2.2 to 2.4 Ib
of solids per year per cu ft (36 to 39 kg/m3) of capac-
ity. A minimum of two separate lagoons are provided
to ensure availability of storage space during clean-
ing, maintenance, or emergency conditions.
• General Guidance. Lagoons may be of any shape,
but a rectangular shape facilitates rapid sludge re-
moval. Lagoon dikes should have a slope of 1:3,
vertical to horizontal, and should be of a shape and
size to facilitate maintenance, mowing, passage of
maintenance vehicles atop the dike, and access for
the entry of trucks and front-end loaders into the
lagoon. Surrounding areas should be graded to pre-
vent surface water from entering the lagoon. Return
must exist for removing the surface liquid and piping
to the treatment plant. Provisions must also be made
for limiting public access to the sludge lagoons.
Design criteria for drying lagoons are presented in
Table 7-7; Table 7-8 lists advantages and disadvantages
of sludge drying lagoons.
7.5.4 Design of Piles and Mounds
Piles and mounds are sites where dewatered sludge is
placed on part of the POTW property as final disposal.
In general, piles and mounds are suitable only for stabi-
lized sludges with a high chemical content (greater than
40 percent lime plus some ferric) or a very low organic
content (less than 50 percent solids), or for highly stabi-
lized lagoon sludges. Piles of mechanically dewatered
sludge with less than 25 percent solids usually lose all
semblance of stability when exposed to extensive rain-
fall (U.S. EPA, 1979).
As surface disposal facilities, piles and mounds are
subject to the requirements of the Part 503 rule (e.g.,
requirements for pathogen control, vector attraction re-
duction, pollutant limits, siting, restriction of public ac-
cess, runoff collection, and ground-water protection). To
protect ground water, it is recommended that piles and
mounds be located on an impervious surface (U.S. EPA,
1990). Many states also have regulations regarding
sludge stockpiles. Check with your state for any specific
state requirements for sludge stockpiles.
7.5.5 Slope Stability and Dike Integrity
Certain types of monofills (area fills) and surface im-
poundments are constructed abovej natural grade
through the use of earthen dikes, excavated below
grade slopes constructed around the unit, or some com-
bination of dikes and excavation, depending on site
topography. These excavated slopes and earthen dikes
are vulnerable to stability failures via several mecha-
nisms. Slope and dike failures can seriously damage a
liner system, allowing releases of leachate to surround-
ing soils and ground water.
For these reasons, earthen dikes must be carefully
designed, and excavated slopes must be carefully
evaluated to ensure that they are sufficiently stable to
Table 7-7. Design Criteria for Drying Lagoons (Lue-Hing et al., 1992)
Design Parameter
a. Solids loading rate
Primary sludge
—(lagoon as a digester)
Digested sludge
—(lagoon for dewatering)
b. Area required
Primary sludge
(dry climate)
Activated sludge
(wet climate)
c. Dike height
d. Sludge depth after
decanting—depths of 60 cm
to 1.2 m (2-4 ft) have been
used in very warm climates
e. Drying time for depth of 38
cm (15 in) or less
96.1 kg/m /year
(6 Ibs/ft3/year)
35-38 kg/m3/year
(2.2-2.4 Ibs/ff/d)
0.0929 mz/capita
(1 ft/Vcapita)
0.31586 m2/capita
(3.4 ft2/capita)
60 cm (2 ft)
38 cm (15 in.)
3 to 5 months
114
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Table 7-8. Advantages and Disadvantages of Using Sludge Drying Lagoons (U.S. EPA, 1979)
Advantages Disadvantages
Lagoons are low energy consumers
Lagoons consume no chemicals
Lagoons are not sensitive to sludge
variability
The lagoons can serve as a buffer in the
sludge handling flow stream. Shock
loadings due to treatment plant upsets'
can be discharged to the lagoons with
minimal impact
Organic matter is further stabilized
Of all the dewatering systems available,
lagoons require the least amount of
operation attention and skill
If land is available, lagoons have a very
low capital cost
Lagoons may be a source of periodic odor
problems, and these odors may be difficult
to control
There is a potential for pollution of
groundwater or nearby surface water
Lagoons can create vector problems (for
example, flies and mosquitos)
Lagoons are more visible to the general
public
Lagoons are more land-intensive than fully
mechanical methods
Rational engineering design data are
lacking to allow sound engineering
economic analysis
withstand the loading and hydraulic conditions to which
they will be subjected during the unit's construction,
operation, and post-closure periods. This section de-
scribes how to design and evaluate dikes and slopes for
stability. For more information on slope stability and dike
integrity at land disposal facilities, including information
on materials specifications and embankment construc-
tion, the-reader is referred to references U.S. EPA,
1988a, and U.S. EPA 1993a.
*'_.-*" v- " , -".
7.5.5.1 Slope Stability Failure . :
Sloperstabiiity failures occur when sliding forces from
the'weight of the soil mass itself and external forces
including sludge pressures exceed the resisting forces
from the strength of the soil and from, any reinforcing
structures. Slope stability analysis' consists of a com-
parison of these resisting forces (or:moments) to the
sliding forces" (or moments) to obtain, a factor of
safety (FS). Generally, the FS takes the following form
(Sowers, 1979):
FS =
Sum of resisting moments
Sum of sliding moments
When a stability analysis is performed, a slope is ana-
lyzed for one or more of several potential modes of
failure. A safety factor is obtained for each mode, the
lowest FS being the most critical.
Table 7-9 lists the EPA-recommended minimum factors
of safety for slope stability analyses. If a dike or exca-
vated slope design analysis yields lower safety factors,
then steps should be taken to reduce the sliding forces
or increase the resisting forces, or the slope should be
redesigned to produce a safer structure.
Slope stability failures usually occur in one of three
major modes, depending on the site soils, slope configu-
ration, and hydraulic conditions (U.S. Dept. of the Navy,
1982). These three major failure modes are the following:
• Rotation on a curved slip surface approximated by a
circular arc.
• Translation on a planar surface that is large com-
pared to the depth below ground.
• Displacement of a wedge-shaped mass along one or
more planes of weakness in the slope.
Figure 7-19 illustrates basic concepts of rotational and
translational failures.
In addition to the three major failure modes, dikes and
excavated slopes are also vulnerable to failure due to
differential settlement, seismic effects including lique-
faction, and seepage-induced piping failure. Safety fac-
tors are determined in a manner similar to those for the
three major failure modes. These failure modes are
discussed in greater detail below.
7.5.5.2 Stability Analyses
A stability analyses should consider (U.S. EPA, 1988a):
• The adequacy of the subsurface exploration program.
• The stability of the dike slopes and foundation soils.
• Liquefaction potential of the soils in the dike and the
foundation.
• The expected behavior of the dike when subjected to
seismic effects.
• Potential for seepage-induced piping failure.
• Differential settlements in the dike.
Subsurface Exploration Program
As discussed in Section 7.5.1, field investigations are
necessary to evaluate the foundation for a constructed
dike, to evaluate dike materials obtained from a borrow
area, and to evaluate a slope excavated below ground.
Of particular importance in some circumstances are
laboratory strength tests performed on soil samples to
115
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Table 7-8. Ricommended Minimum Values of Factor of Safety for Slope Stability Analyses (U.S. EPA, 1988a)
Uncertainty of Strength Measurements
Consequences of Slope Failure
Smallt
Largea
No imminent danger to human life or major environmental
Impact if slope fails
Imminent danger to human life or major environmental impact if
slope fails
1.25
(1.2)"
1.5
(1.3)
1.5
(1.3)
2.0 or greater
(1.7 or greater)
1. The uncertainty of the strength measurements is smallest when the soil conditions are uniform and high quality strength test
data provide a consistent, complete, and logical picture of the strength characteristics.
2. The uncertainty of the strength measurements is greatest when the soil conditions are complex and when available strength
data do not provide a consistent, complete, or logical picture of the strength characteristics.
* Numbers without parentheses apply for static conditions and those within parentheses apply to seismic conditions.
Active Wedges
Central Block
Passive Wedges
^ ... —...
x^/py//x4/xx/jx
Elements of the Translation^ (Wedge) Slope Stability Analysis
(Reference 4, p. 42)
Water
a. Circular segment divided into slices
b. Forces acting on slice 3
Method of Slices for Circular Arc Analysis of Slopes in Soils Whose Strength Deoends on Stress (Reference 3. o. 578)
Figure 7-19. Conceptual slope failure models (U,S. EPA, 1988a).
116
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determine the strength of the foundation and embank-
ment soils under the expected conditions of saturation
and consolidation (see Chapter 6).
Field and laboratory data are used to obtain a detailed
characterization of the site with respect to the engineer-
ing properties of the soils and rock. These engineering
properties provide the input data for evaluation of the
stability of slopes. Slope stability analysis requires the
establishment of various site conditions including (U.S.
EPA, 1988a):
• The soil shear strength conditions that represent ac-
tual site conditions.
• The steady-state hydraulic boundary conditions oc-
curring through the site's section.
• The seismic conditions established for the site area.
For slope stability analyses, the most critical soil pa-
rameter is that of shear strength (U.S. EPA, 1988a). The
shear strength of a soil is a measure of the amount of
stress that is required to produce failure in plane of a
cross section of the soil structure. The shear strength of
a soil must be known before an earthen structure can
be designed and built with assurance that the slopes will
not fail (U.S. EPA, 1986b). To adequately determine a
soil's shear strength, the potential effect of pore water
pressures from the expected site loading conditions
must be considered during testing.
While laboratory soil strength testing data is highly de-
sirable, these tests are limited to small-size samples,
and in many locations dikes are constructed using ma-
terial that contains large particle sizes. Furthermore, in
existing dikes, the type of material may make the obtain-
ing of undisturbed soil samples nearly impossible.
Therefore, it is not uncommon in standard engineering
practice to estimate or assume these parameters based
on the best data available. While it is acceptable to do
this, it must be done and evaluated by a qualified
geotechnical engineer (U.S. EPA, 1988a).
Slope stability also is dependent on hydraulic conditions
in the slope. Potential hydrostatic or seepage forces
from large hydraulic gradients should be identified and
considered during the stability analyses. Ground-water
levels and hydraulic analyses are used to determine the
configuration of the steady-state piezometric surface
through sections of the foundation and/or the dike struc-
ture. For sections involving a steep piezometric surface
or an upstream static or flood pool, hydraulic analyses
also determine seepage quantity, critical (highest) exit
gradient, and potential for uplift of a clay liner due to
excess pore pressures produced by a confined seepage
condition (U.S. EPA, 1986b).
Hydraulic boundary conditions may reflect unconfirmed,
steady-state seepage conditions, or confined seepage
conditions involving an impermeable barrier (soil liner)
and excess pore pressure on the barrier. The hydraulic
conditions of a slope are determined using seepage
analysis, as discussed by Freeze and Cherry (1979).
Slope Stability
Slope stability analyses are performed for both exca-
vated side slopes and aboveground embankments.
Three analyses will typically be performed as appropri-
ate to verify the structural integrity of a cut slope or dike;
they are (U.S. EPA, 1988a):
• Slope stability
• Settlement
• Liquefaction
Table 7-10 indicates the minimum required soil parame-
ter data usually needed to perform these analyses.
The slope stability is typically evaluated using either a
rotational (slip circle) analysis and/or a translational
(sliding block or wedge) analysis using a computer
model. These analyses are run for both static and dy-
namic (seismic) conditions. For large dikes in areas of
major earthquakes, a more rigorous method of dynamic
analysis may be warranted.
Analyses to establish total and differential settlement
are also performed to ensure that the estimated settle-
ment will not adversely affect the integrity of the unit and
its components.
The liquefaction analysis determines the potential for
liquefaction of the dike and foundation soils to occur
during seismic events.
Rotational Slope Stability Analysis. A rotational slope
stability analysis is typically performed using a method
that divides the slope into discrete slices and sums all
driving and resisting forces on each slice (see Figure
7-19). For each trial arc, the section is subdivided into
vertical slices, each having its base coincident with a
portion of the trial arc. Slices are defined according to
the section geometry such that the base of each slice
comprises only one soil type. The driving and resisting
forces acting on each slice are then used to compute
driving and resisting moments about the center of rota-
tion of a circular section of the slope. The overturning
and resisting moments for each slice are then summed
and the FS is computed (U.S. EPA, 1986b).
Translational Slope Stability Analysis. The major fea-
tures of the translational analysis are the same as those
for the rotational case except that the trial surface con-
sists of straight line segments that form the base of one
or more active (thrusting) wedges, a neutral or thrusting
central block, and one .or more passive (restraining)
wedges (see Figure 7-19). This analysis is based upon
selection of a trial central block defined by the surface
and subsurface soil layer geometry, followed by compu-
117
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Table 7-10. Minimum Data Requirements for Stability Analysis Options (U.S. EPA, 1988a)
Stability Analysis Options
Soil Parameter
1. Cohesion* (UU. CU, CD cases)
2. Angle of internal friction* (UU. CU. C
cases)
3. Total (wet) unit weight
4. Clay content
5. Overconsolkfation ratio
6. Initial void ratio
7. Compression index
8. Recompression index
9, Hydraulic conductivity" (permeability, k)
10. Median grain size
11. Plasticity index (PI)
12. Liquid limit (LL)
13. Standard penetration number (N)
Units Rotational
pounds/sq.ft. (psf) X
degrees X
pounds/cu. ft. (pcf) X
percent (0 to 100)
unitless (decimal)
unitiess (decimal)
unitless (decimal)
unitless (decimal)
; ft/yr
mm
percent (0 to 100)
percent (0 to 1 00)
unitless (integer)
Translational Settlement Liquefaction
X XCD
X
XXX
X
X
X
X
X
X
X
X
X
Required strength case dependent upon hydraulic boundary condition selected
Used only in hydraulic analysis
tation of the coordinates for the associated active and
passive wedges (U.S. EPA, 1986c).
Settlement Analysis. Settlement analysis is used to de-
termine the compression of foundation soils due to
stresses caused by the weight of an overlying dike.
Required parameters for each soil include unit weight,
initial void ratio, compression and recompression indi-
ces, and the over-consolidation ratio (U.S. EPA, 1986c).
Settlements are calculated at the toes, crest points, and
centerline of the dike. The consolidation of each soil is
calculated for each layer and summed up for all soils to
determine the total settlement at each point. Differential
settlements are calculated between each toe and crest,
toe and centerline, and crest and centerline on both
sides of the dike. Recommended maximum differential
settlements can be found in EPA, 1986c.
Liquefaction Analysis. Factors that most influence lique-
faction potential are soil type, relative density, initial
confining pressure, and the intensity and duration of
earthquake motion (U.S. EPA, 1986c). Methods for es-
timating the potential for liquefaction are provided in a
computer software package called Geotechnical Analy-
sis for Review of Dike Stability (CARDS) that has been
developed by EPA's Risk Reduction Engineering Labo-
ratory (RREL) to assist permit writers and designers in
evaluating earth dike stability. GARDS details the basic
technical concepts and operational procedures for the
analysis of site hydraulic conditions, dike slope and
foundation stability, dike settlement, and liquefaction po-
tential of dike and foundation soils. It is designed to meet
the expressed need for a geotechnical support tool to
facilitate evaluation of existing and proposed dike struc-
tures at hazardous waste sites.
For additional information on seismic risk zones of the
United States, the range of seismic parameters for
source zones, and GARDS, the reader is referred to
EPA, 1986c.
7.5.5.3 Slope; Stability Design Plans
The design plans for dikes and cut slopes should show
the design layout, cross sections portraying the pro-
posed grade and bearing elevations relative to the ex-
isting grade, and details of the dikes or cut slopes,
including all slope angles and dimensions. Materials
present at the cut slope or to be used to construct the
dike must be adequately characterized (see EPA,
1986b). This design configuration then must be evalu-
ated for its stability under all potential hydraulic and
loading conditions. If the stability analyses result in un-
acceptably low factors of safety, then the design must
be modified to stabilize the slope. The revised design must
then be evaluated to verify that it is sufficiently stable.
In addition, in a monofill or surface impoundment, often
the cut slopes or dikes will not be identical around the
entire perimeter of the unit. For this reason, it is impor-
tant that the most critical slope or dike section be iden-
tified for analysis. Generally, the most critical section will
be the steepest and/or the highest portion of the slope
or dike. Particularly in a cut slope, however, the in situ
materials may vary enough that the more critical slope
may be shallower or flatter, but may be composed of
weaker soils or may be subject to significant pore pres-
sures or seepage from high ground-water levels.
7.5.6 Liner Systems
Current regulations for sewage sludge surface disposal
sites (Part 503, Subpart C) do not require that land
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disposal facilities be constructed with liner systems.
Twenty-eight states and Puerto Rico, however, do spec-
ify some requirement for liners at sludge landfills (U.S.
EPA, 1990). Under the Part 503 regulation, where there
is a liner, the owner/operator of a surface disposal site
must maintain and operate a leachate collection system
(see Section 7.2.1). This section provides criteria for the
design and construction of liner systems and reviews
liner system designs on a component-by-component
basis. An extensive body of literature has been devel-
oped on the design of liners and leachate collection
systems. For additional information on these systems,
including information on materials specifications, con-
struction procedures, and quality control issues, see the
references U.S. EPA, 1988a, and U.S. EPA, 1993b.
There are two types of liner systems currently used in
land disposal facilities. A single liner system consists of
one liner and one leachate collection system as shown
in Figure 7-20. A double liner system includes two liners
(primary and secondary), with a primary leachate collec-
tion system above the primary (top) liner and a secon-
dary leak detection/leachate collection system between
the two liners, as shown in Figure 7-21.
The term "liner system" includes the liner(s), leak detec-
tion/leachate collection system(s), and any special ad-
ditional structural components such as filter layers or
reinforcement. The major components of both single
and double liner systems are the following:
• Low-permeability soil liners
• Flexible membrane liners (FML)
• Leachate collection and removal systems (LCRS)
7.5.6.1 Low-Permeability Soil Liners
Low-permeability soil liner design is siter and material-
specific. Prior to design, many fundamental yet impor-
tant criteria should be considered such as: in-place
permeability of the liner; liner stability against slope
failure, settlement, and bottom heave; and the long-term
integrity of the liner.
Important criteria to consider when reviewing a design
for a soil liner include (U.S. EPA, 1988a):
• Liner site and material selection
• Hydraulic conductivity
• Liner thickness
• Strength and bearing capacity
• Slope stability and controls for liner failure
These design considerations are important throughout
the installation and construction phases of a clay liner.
Site and Material Selection
A site investigation should be conducted prior to the
design phase, and the following factors should be con-
sidered (see Chapter 6):
• Site geology
• Topography (especially drainage patterns)
• Analyses of soil properties
• Field and laboratory hydraulic conductivity
• Bedrock characteristics
• Hydrology
• Climate
Protective
Soil or Cover
(optional)
Filter Medium
Leachate
Collection and
Removal System
Being Proposed as the
Leak Detection System
Low Permeability Soil
Native Soil Foundation
Lower Component
(compacted soil)
(Not to Scale)
Figure 7-20. Schematic of a single clay liner system for a landfill (U.S. EPA, 1988a).
119
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Protective
Soil or Cover
(optional)
Filter Medium
Top Liner
(FML)
Bottom Composite
Liner
Primary Leachate
Collection and
Removal System
Secondary Leachate
Collection and
Removal System
Being Proposed as the
Leak Detection System
Upper
Component
(FML)
Native Soil Foundation
Leachate
Collection
System
Sump
Lower Component
(compacted soil)
Figure 7-21. Schematic of a double liner and leak detection system for a landfill (U.S. EPA, 1988a).
All these factors are important to the design of the soil
liner. The site will require a foundation designed to con-
trol settlement and seepage and to provide structural
support for the liner (see Section 7.5.1). If satisfactory
contact between the liner and the natural foundation is
achieved, settlement and cracking will be minimized
(U.S. EPA, 1988a).
Soil liners for sewage sludge disposal units must meet
the following requirements:
• Afield hydraulic conductivity of 1 x 10'7 cm/sec when
compacted.
• Sufficient strength after compaction to support itself
and the overlying materials without failure.
Soil liner material may originate at the site or may be
hauled in from a nearby borrow site if the native soil is
not suitable. If the available soils do not achieve the
specified hydraulic conductivity, it may be necessary to
introduce a soil additive to increase the performance
potential of the selected material. The most common
additive used to amend soils is sodium bentonite (U.S.
EPA, 1993b). Although soil additives are known to de-
crease hydraulic conductivity, it is important to test ad-
ditives under actual field conditions as with any potential
soil liner material (U.S. EPA, 1987b). For additional
information on soil additives, see U.S. EPA, 1993b.
Because physical properties differ from one soil to the
next, testing procedures are necessary to assist in the
selection of liner material. Once potential soil sources
have been identified, it is necessary to begin testing to
eliminate undesirable soils or to determine whether the
source requires an amendment. Many procedures have
been standardized for soil testing by organizations such
as the American Society of Testing and Materials (ASTM)
and by individuals currently researching clay soils for
use in soil liner construction (ASTM, 1987; U.S. EPA, 1986d).
Representative samples of the proposed material must
be subjected to laboratory testing. This will establish the
properties of the material with respect to water content,
density, compactive effort, and hydraulic conductivity.
Clay soils exhibit characteristic changes when com-
pacted; therefore, all analyses of a potential material
must be performed on a compacted sample. Table 7-11
provides a listing of pertinent soil tests and methods
(U.S. EPA, 1986d).
Thickness
Two feet of soil is generally considered the minimum
thickness needed to obtain adequate compaction to met
the hydraulic conductivity requirement (U.S. EPA,
1993b). Liners are designed to be of uniform thickness
over the entire facility. The 2-ft minimum thickness is
believed to be sufficient to inhibit hydraulic short-circuit-
ing of the entire layer (U.S. EPA, 1993b). Thicker areas
may be encountered wherever there may be recessed
areas for leachate collection pipes or collection sumps.
Some engineers suggest extra thickness and compac-
tive effort for the edges of the sidewalls to adequately
tie them together with the liner itself. In smaller facilities,
a soil liner may be designed for installation over the
entire area, but in larger or multicell facilities, liners are
designed in segments. If this is the case, it will be
necessary to specify in the design a beveled or step-cut
joint between segments to ensure that the segments
properly adhere together (U.S. EPA, 1988b).
Hydraulic Conductivity
The coefficient of permeability or hydraulic conductivity
expresses the ease with which water passes through
a soil. Achieving the hydraulic conductivity standard
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Table 7-11. Methods for Testing Low-Permeability Soil Liners
(U.S. EPA, 1988a)
Parameter to be
Analyzed
SoMtyp*
Moisture content
In-place density
Moisture-density
Methods
Vitual -manual
procedure
Particle size analysis
Atterberg limits
Soil classification
Oven-dry method
Nuclear method
Calcium carbide
(speedy)
Nuclear methods
Sand cone
Rubber balloon
Drive cylinder
Standard effort
Test Method Reference
ASTMD24W
ASTMD422
ASTM 04318
ASTM 02487
ASTM D2216
ASTM 03017
AASHTO T217
ASTM D2922
ASTMD15S6
ASTM D2167
ASTM D2937
ASTM 0698
relations
Strength
Cohesive soil
consistency (field)
Hydraulic conductivity
(laboratory)
Modified effort
Unconfirmed
compressive strength
Triaxial compression
Penetration tests
Field vane shear test
Hand penetrometer
Fixed-wall double ring
permeameter
Flexible wall
permeametar
Hydraulic Conductivity Sealed Doubte-Rind
(field) Infiltrometer
Sai-Anderson-Gill
double-ring
Infittrorrwtor
ASTM Oi 557
ASTM 02166
ASTM 02850
ASTM D3441
ASTM 02573
Horslev, 1943
EPA, 1983 SW-870
Anderson et al,
1984
Daniel et at., 1985
SW-846 Method
9100 (EPA, 1984)
Day and Daniel,
1985
Anderson et a).,
1984
(1 x 10~7 cm/sec) depends on the degree of compaction,
compaction method, type of clay, soil moisture content,
and density of the soil during liner construction (U.S.
EPA, 1993b). Hydraulic conductivity is the most critical
design criterion for a potential soil liner (U.S. EPA,
1988a). The hydraulic conductivity of a soil depends in
part on the viscosity and density of fluid flowing through
it. The hydraulic conductivity of a partially saturated soil
will be less than the hydraulic conductivity of the same
soil when saturated. Because invading water only flows
through water-filled voids (and not air-filled voids), the
dryness of a soil tends to lower its permeability (U.S.
EPA, 1993D).
When designing a soil liner, field hydraulic conductivity
is the most important factor to consider. Hydraulic con-
ductivity testing should be conducted on samples that
are fully saturated to attempt to measure the highest
possible hydraulic conductivity (U.S. EPA, 1993b).
Strength and Bearing Capacity
Another important criterion to consider when designing
a soil liner is the strength and bearing capacity of the
liner material. Analysis of these parameters will deter-
mine the stability of the liner material. More detailed
discussions of bearing capacity and strength can be
found in Section 7.5.1.3.
Slope Stability
The strength of a soil also controls its resistance to
sliding. Failure of a liner slope can result in slippage of
the compacted soil liner along the excavated slope.
Therefore, analysis of slope stability must be considered
in the design of a soil liner (see Section 7.5.5).
7.5.6.2 Flexible Membrane Liners (FMLs)
The design of a lined sewage sludge surface disposal
site requires consideration of more than the perform-
ance requirements of the FML; it also requires careful
design of the foundation supporting the FML (see Sec-
tion 7.5.1). The foundation provides support for the liner
system, including the FMLs and the leachate collection
and removal systems. If the foundation is not structurally
stable, the liner system may deform, thus restricting or
preventing its proper performance.
Performance Requirements of the FML
The performance requirements of an FML include (U.S.
EPA, 1988a):
• Low permeability to waste constituents
• Strength or mechanical compatibility of the sheeting
• Durability for the lifetime of the facility
The designer must specify the necessary criteria for
each of these properties based on engineering require-
ments, performance requirements, and the specific site
conditions. In addition, the FML design must be compat-
ible with the present technology, used in the installation
of FMLs (U.S. EPA, 1988c).
These performance requirements are assessed through
laboratory and pilot-scale testing of the various proper-
ties of FML sheeting (U.S. EPA, 1988c). The analyses
and tests that are performed on FML sheeting measure
its inherent analytical properties, physical properties,
permeability characteristics, environmental and aging
properties, and performance properties (U.S. EPA,
1988c). Testing is essential to the designer/engineer
who uses the data to determine whether a specific FML
sheeting will meet the design requirements of the waste
facility. These tests are discussed in detail in the refer-
ences U.S. EPA, 1983a, and U.S. EPA, 1988c.
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Permeability
The primary function of a liner system in a sewage
sludge surface disposal site is to minimize and control
the flow of leachate from the site to the environment,
particularly the ground water. A properly designed FML
has a low permeability to the sewage sludge contained
within the liner, allowing it to perform its primary function.
Mechanical Compatibility
An FML must be mechanically compatible with the de-
signed use of the lined facility in order to maintain its
integrity during and after exposure to short-term and
long-term mechanical stresses. Short-term mechanical
stresses can include equipment traffic during the instal-
lation of a liner system, as well as thermal expansion
and shrinkage of the FML during operation of the unit.
Long-term mechanical stresses usually result from the
placement of sewage sludge on top of the liner system
or from differential settlement of the subgrade (U.S.
EPA, 1988c).
Mechanical compatibility requires adequate friction be-
tween the components of a liner system, particularly the
soil subgrade and the FML, to ensure that slippage or
sloughing does not occur on the slopes of the unit.
Specifically, the foundation slopes and the subgrade
materials must be considered in design equations in
order to evaluate (U.S. EPA, 1988c):
• The ability of an FML to support its own weight on
the side slopes.
• The ability of an FML to withstand downdragging dur-
ing and after filling.
• The best anchorage configuration for the FML.
• The stability of a soil cover on top of an FML.
Durability
An FML must exhibit durability; that,is, it must be able
to maintain its integrity and performance characteristics
over the operational life and the post-closure care period
of the unit. The service life of an FML is dependent on
the intrinsic durability of the FML material and on the
conditions to which it is exposed (U.S. EPA, 1988c; EPA,
1987a; EPA, 1987b).
Selection of the FML
The performance requirements determined by a de-
signer/engineer serve as the basis for the selection of
an FML for a given facility. Based upon the designed
use of the unit, the designer must make decisions on
the composition, thickness, and construction (fabric-
reinforced or unreinforced) of an FML. Mechanical com-
patibility and sometimes permeability determine the
thickness of the FML sheeting. It should be noted that
liner performance does not correlate directly with any
one property (e.g., tensile strength) and that specifica-
tions that appear in specific technical resource docu-
ments such as the reference EPA, 1988c, should not be
used alone as the basis for selection of an FML.
FMLs are made of polymeric materials, particularly plas-
tics and synthetic rubbers. There are four general types
of polymeric materials used in the manufacture of FML
sheeting (U.S. EPA, 1988c):
• Thermoplastics and resins, such as PVC and EVA
• Semicrystalline plastics, such as polyethylenes
The various polymers are used to make a variety of
liners that can be classified by production process and
reinforcement. Table 7-12 lists the polymers currently
used in lining materials (U.S. EPA 1988c).
The polymers used in FMLs have different physical and
chemical properties, and they also differ in method of
installation and seaming as well as costs. The reference
U.S. EPA, 1988c, provides detailed information about the
composition and properties of each of these polymers.
Seaming of FML Sheeting
The construction of a continuous watertight FML is criti-
cal to the containment of leachate and is heavily de-
pendent on the construction of the seams bonding the
sheeting together. The seams are the most likely source
of failure in an FML. Sheeting is seamed together both
in the factory and in the field. Sheeting manufactured in
relatively narrow widths (less than 90 in.) is seamed
together to fabricate panels. These factory seams are
made in a controlled environment and are generally of
high quality. Both fabricated panels and sheeting of
wider widths (21 to 64 ft) are seamed oh site during the
installation of the FML. The quality of field seams is
difficult to maintain since the installer must deal with
changing weather conditions, including temperature,
wind, and precipitation, as well as construction site con-
ditions, which include unclean work areas and working
on slopes. Constant inspection under a construction
quality assurance plan is necessary to ensure the integ-
rity of field searns (U.S. EPA, 1988c).
Several bonding systems are available for the construc-
tion of factory and field seams in FMLs. Bonding sys-
tems include solvent methods, heat seals, heat guns,
dielectric seaming, extrusion welding, and hot wedge
techniques. The selection of a bonding system for a
particular FML is dependent primarily on the polymer
making up the sheeting (U.S. EPA, 1988a).
7.5.7 Leachate Collection and Removal
Systems (LCRSs)
Leachate refers to liquid that has passed through or
emerged from sewage sludge and contains dissolved,
suspended, or immiscible materials removed from the
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Table 7-12. Polymers Currently Used in FMLs for Waste Management Facilities (U.S. EPA, 1988c)
Type of compound used in liners Fabric reinforcement
Polymer
Chlorinated polyethylene (CPE)
Chlorosulfonated polyethylene (CSPE)
Elasticized polyvinyl chloride (PVC-E)
Polyester elastomer (PEL)
Polyethylene (LDPE, LLDPE, HOPE)
Polyvinyl chloride (PVC)
Thermoplastic
Yes
Yes
Yes
Yes
Yes
Yes
Cross-linked
Yes
Yes
No
No
No
No
With
Yes
' Yes
Yes
Yes
No
Yes
Without
Yes
No
No
Yes
Yes
Yes
sewage sludge. The primary function of the leachate
collection system is to collect and convey leachate out
of the surface disposal unit and to control the depth of
the leachate above the liner (U.S. EPA, 1993b).
Leachate is generally collected from the surface dis-
posal unit through sand drainage layers, synthetic drain-
age nets, or granular drainage layers with perforated
plastic collection pipes, and is then removed through
sumps or gravity drain carrier pipes. An LCRS should
consist of the following components (U.S. EPA, 1988a):
• A low-permeability base that is either a soil liner,
composite liner, or flexible membrane liner (FML).
• A high-permeability drainage layer constructed of
either natural granular materials (sand and gravel) or
synthetic drainage material (geonet) that is placed
directly on the primary and/or secondary liner or its
protective bedding layer.
• Perforated leachate collection pipes within the high-
permeability drainage layer to collect leachate and
carry it rapidly to the sump.
• A protective filter material surrounding the pipes, if
necessary, to prevent physical clogging of the pipes
or perforations.
• A leachate collection sump or sumps, where leachate
can be removed.
• A protective filter layer over the high-permeability
drainage material that prevents physical clogging of
the material.
• A final protective layer of material that provides a
wearing surface for traffic and landfill operations.
The design features of each of these components and
operation of the entire LCRS is summarized below. For
more detailed information, see the references U.S. EPA,
1993b, and U.S. EPA, 1988a.
7.5.7.1 Grading and Drainage
For leachate to be effectively collected and removed,
liner systems must be sloped to drain toward their respec-
tive collection sumps. The recommended bottom liner
slope is 2 percent at all points in each system (U.S. EPA,
1987b). This slope is necessary for effective leachate
drainage through the entire operating and post-closure
period; therefore, these slopes must be maintained un-
der operational and post-closure loadings. The settle-
ment estimates performed as discussed in Section 7.5.1
must be evaluated to ensure that the slopes will be 2
percent throughout the period of operation of the LCRS.
It may be necessary to initially design the slopes steeper
than 2 percent to allow for settlement (U.S. EPA, 1988a).
Good engineering practice requires that the design, con-
struction, and operation of the LCRS should maintain a
maximum height of leachate above the composite liner
of 30 cm (12 in.). Design guidance for calculating the
maximum leachate depth over a liner for granular drain-
age system materials is provided in U.S. EPA, 1989.
Granular Drainage Layers and Geosynthetic Drainage
Layer-Geonets
The high-permeability drainage layer is placed directly
over the liner or the protective bedding layers. Often the
selection of a drainage material is based on the onsite
availability of natural granular materials. Since hauling
costs are high for sand and gravel, a facility may elect
to use geonets or synthetic drainage materials as an
alternative. Frequently, geonets are substituted for
granular materials on steep sidewalls in order to provide
a layer that is more stable with respect to sliding than a
granular layer.
Geonets may be substituted for the granular layers in
either of the LCRSs on the bottoms and sidewalls of the
landfill cells. Geonets may be used if their charac-
teristics are in keeping with design, including chemical
compatibility, flow under load, clogging resistance, and
protection of the FML (U.S. EPA, 1987c).
Piping
The design of piping systems requires the consideration
of pipe flow capacity and structural strength/The spac-
ing of leachate collection pipes can be determined
based on the maximum allowable leachate head on the
liner. This maximum head calculation assumes that liq-
uids can drain away freely through the piping systems;
therefore, the pipes must be sized to carry the expected
flow (U.S. EPA, 1988a).
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The leachate piping configuration shown on facility de-
sign drawings should be evaluated for its ability to main-
tain the maximum leachate head and for its ability to
carry the expected flows.
Sumps, located in a recess at the low point(s) within the
leachate collection drainage layer, provide one method
for leachate removal from a surface disposal unit. These
sumps typically house a submersible pump, which is
positioned close to the sump floor to pump the leachate
and to maintain a 30 cm (12 in.) maximum leachate
depth. Pumps used to remove leachate from sumps
should be sized to ensure removal of leachate at the
maximum rate of generation. These pumps also should
have a sufficient operating capacity to lift the leachate
to the required height from the sump to the access port.
Portable vacuum pumps can be used if the required lift
height is within the limit of the pump. They can be moved
in sequence from one leachate sump to another. The
type of pump specified and the leachate sump access
pipes should be compatible and should consider per-
formance needs under operating and closure conditions
(U.S. EPA, 1988a).
Alternative methods of leachate removal include internal
standpipes and pipe penetrations through the geomem-
brane, both of which allow leachate removal by gravity
flow to either a leachate pond or exterior pump station.
If a leachate removal standpipe is used, it should be
extended through the entire surface disposal unit from
liner to cover and then through the cover itself. If a
gravity drainage pipe that requires geomembrane pene-
tration is used, a high degree of care should be exer-
cised in both the design and construction of the
penetration so that it allows nondestructive quality con-
trol testing of 100% of the seal between the pipe and the
geomembrane. If not properly constructed and fabri-
cated, geomembrane penetrations can cause leakage
through the geomembrane (U.S. EPA, 1993b).
The HELP Model
EPA has developed a computer program called the Hy-
drologic Evaluation of Landfill Performance (HELP),
which is a quasi-two-dimensional hydrologic model of
water movement across, into, through, and out of land-
fills. The model uses climatologic, soil, and landfill de-
sign data and incorporates a solution technique that
accounts for the effects of surface storage runoff, infil-
tration, percolation, evapotranspiration, soil moisture
storage, and lateral drainage. The program estimates
runoff drainage and leachate expected to result from a
wide variety of landfill conditions, including open, par-
tially open, and closed landfill cells. Most importantly, in
consideration of this topic, the model can be used to
estimate the buildup of leachate above the bottom liner
of the landfill. The HELP program can be used to esti-
mate the depth of leachate above the bottom liner for a
variety of landfill designs, time averages, and storm
events. The results may be used to compare designs or
to design leachate drainage and collection systems.
References U.S. EPA, 1984a, and U.S. EPA, 1984b, a
user's guide and model documentation, respectively,
should be obtained before attempting to run the HELP
model. Version 3.0 of the HELP model became available
during the fall of 1993. To obtain a copy, call EPA's Office
of Research and Development (ORD) in Cincinnati at
513-569-7871.
7.5.7.2 System Strength
All components of the LCRS must have sufficient
strength to support the weight of the overlying sewage
sludge, cover system, and post-closure loadings, as well
as stresses from operating equipment and from the
weight of the components themselves. LCRs are also
vulnerable to sliding under their own weight and the
weight of equipment operating on the slopes. The com-
ponents that are most vulnerable to strength failures are
the drainage layers and piping. LCRS piping can fail by
excessive deflection leading to buckling or collapsing.
Sidewall Stability
For liner systems placed on excavated sidewalls, the
issue of the stability of the individual liner components
on the slope, including the LCRS, must also be consid-
ered. Koerner (1986) provides a method for calculating
the factor of safety against sliding for soils placed on a
sloped FML surface. It considers the slope angle and
the friction angle between the FML and its cover soil.
From the slope angle and the FS, a minimum allowable
friction angle is determined, and the various compo-
nents of the liner system are selected based on this
minimum friction angle. If the design evaluation results
in an unacceptably low FS, then either the sidewall slope
or the materials must be changed to produce an ade-
quate design.
Stability of Drainage Layers
If the drainage layer of the LCRS is constructed of
granular soil materials (i.e., sand and gravel), then this
granular drainage layer must be shown to have sufficient
bearing strength to support expected loads. The
leachate system design should provide calculations
demonstrating that the selected granular drainage ma-
terials will be stable on the steepest slope (i.e., the most
critical) in the design. The calculations and the assump-
tions should be shown, especially the friction angle be-
tween the geomembrane and soil, and if possible,
supported by laboratory and/or field testing data.
Pipe Structural Strength
Pipes installed at the base of a landfill can be subjected
to high loading of waste. The evaluation of a design
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should consider both the maximum depth of fill over the
piping and the loading exerted by landfill equipment on
a pipe with very little cover. The pipe must be selected
based upon the most critical of these loadings.
Leachate collection pipes beneath land disposal facili-
ties are generally installed in one of two configurations:
• A trench condition, where the pipe is placed in a
shallow trench excavated into the underlying soil liner
or foundation soil and does not project above the top
of the trench.
• A positive projecting condition, where the pipe is
placed directly upon a lower liner system component
and projects above it.
Loads on the pipe in the trench condition are caused by
both the fill material and the trench backfill. These two
loads are computed separately and then added to obtain
the total vertical pressure acting on the top of the pipe.
For the projecting condition the vertical pressure on the
pipe is assumed to be equal to the unit weight of the fill
multiplied by the height of the fill above the pipe (U.S.
EPA,1988a).
In the early phases of landfilling the piping system is
subject to concentrated and impact loadings from trucks
and landfill equipment. Since the pipe at this point may
be covered with only a foot or so of granular drainage
material, wheel and impact loads are transmitted directly
to the pipes. These loads may be calculated using a
method found in the reference ASCE/WPCF, 1969. This
traffic load should be compared to the static load from
the waste, and the pipe selected based upon the larger
of the two loads.
Pipes are slotted or perforated to allow flow of leachate
into the collection system. These perforations reduce
the effective length of the pipe available to carry loads
and to resist deflection. See U.S. EPA, 1983a for a
discussion of how to allow for perforations in pipe
strength calculations.
7.5.7.3 Prevention of Clogging
The piping system must be protected from physical
clogging by the granular drainage materials. This is most
effectively accomplished by careful sizing of pipe perfo-
rations and by surrounding the pipe with a filter medium,
either a graded granular filter or a geotextile material (a
filter fabric). In addition, clogging of the pipes and drain-
age layers of the LCRS can occur through several other
mechanisms, including chemical and biological clog-
ging. For more information on these mechanisms, see
U.S. EPA, 1988a.
To prevent physical clogging of leachate drainage layers
and piping by soil sediment deposits, filter and drainage
layer size gradations should be designed using criteria
established by the Army Corps of Engineers. Drainage
layers should be designed to have adequate hydraulic
conductivity; and granular drainage media should be
washed before installation to minimize fines. Drain pipes
should be slotted or perforated with a minimum inside
diameter of 6 in. to allow for cleaning.
Two criteria are suggested for use in design of drainage
and filter layers for drain systems. The first criterion is
for the control of clogging by piping ofsmall soil particles
into the filter layer and the drain pipe system, while the
second criterion is meant to guarantee sufficient perme-
ability to prevent the buildup of large seepage forces and
hydrostatic pressure in filters and drainage layers. When
geotextiles are used in place of graded filters, the pro-
tective filter may be only about 1 mm in thickness.
Caution should be exercised to ensure that no holes,
tears, or gaps are permitted to form in the fabric. The
advantages to using geotextiles in place of granular
filters are cost, uniformity, and ease of installation. With
increases in costs of graded aggregate and its installa-
tion, geotextiles are competitive with graded filters. One
of the most important advantages to geotextiles is qual-
ity control during construction. The properties of geotex-
tiles will remain practically constant independent of
construction practices, whereas graded filters can be-
come segregated during placement. These geotextiles
must be designed, and the references Koerner, 1986,
and U.S. EPA, 1987c, provide guidance on how to de-
sign such systems.
When drainage pipe systems are embedded in filter and
drainage layers, no unplugged ends should be allowed,
and the filter materials in contact with the pipes rrjust be
coarse enough to be excluded from joints, holes, or
slots. Specifications for the drainage layer materials
should be checked against pipe specifications to be sure
that the piping system will not become clogged by the
granular drainage layer particles.
7.5.7.4 Layout of System Components
The design of an LCRS for a sewage sludge surface
disposal unit begins with a layout of the system compo-
nents within the unit. This layout should be presented in
plan view, cross-section, and detail drawings of the unit.
The drawings should show dimensions and slopes of
the unit design features and all the components of the
LCRS.
The system components should be shown on the plan
and cross-section drawings and should clearly show the
lateral and vertical extent of the liners. The drawings
should show the elevations of the tops of the liner sys-
tem components at critical points, including the toes of
the sidewalls, the boundaries of any sub-areas of the
unit that drain to different sumps, and the inlet and
low-point elevations of the sumps. This information is
essential to evaluate the ability of the system to drain
leachate toward the collection sumps.
125
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7.5.7.5 Leachate Treatment
Collected leachate may be treated by one or more of the
following methods:
• Discharge to a wastewater collection system or haul
directly to a treatment plant.
• On-site treatment.
- Recycle through the landfill
- Evaporation of leachate in collection ponds
— Onsite treatment plant
Depending on the leachate characteristics, volume, and
local regulations, it may be possible to discharge col-
lected leachate to an existing wastewater system for
subsequent treatment with municipal wastewater. Local
wastewater treatment plant personnel should be con-
sulted about leachate acceptability to determine special
requirements for discharge to the treatment plant (e.g.,
large slugs of highly contaminated leachate may have
to be mixed with municipal wastewater to prevent plant
upsets).
If discharge to the wastewater system is not practical or
if the leachate is potentially disruptive to treatment plant
operations, onsite treatment or transportation to a
chemical waste disposal site will have to be utilized.
Onsite treatment may consist of recycling the leachate
through the landfill, placing the leachate in a shallow
basin to allow it to evaporate, or installing a small (spe-
cially designed) treatment plant on site. Leachate recy-
cling systems are not feasible at most sites; specifically
at areas with high rainfalls and high application rates.
The primary application of such systems should be re-
stricted to codisposal sites in climates where the evapo-
ration rate exceeds rainfall to a significant extent. The
latter alternative should be avoided if at all possible
due to its high cost and the unproven reliability of such
small plants.
7.6 Design for Codisposal with Solid
Waste
Codisposal is the disposal of sewage sludge with house-
hold waste (solid waste) at an MSW landfill. Figure 7-22
presents a generalized flow chart for codisposal of re-
fuse and sewage sludge in a landfill. Methods of codis-
posal include:
• Landfilling a sewage sludge/solid waste mixture.
• Use of sewage sludge/soil mixture or sewage sludge
as daily cover material.
• Use of sewage sludge/soil mixture or sewage sludge
as final cover material.
The design of MSW landfills is regulated by EPA's Solid
Waste Disposal Facility Criteria, 40 CFR Part 258. This
manual does not provide detailed information about
the design of a solid waste landfill receiving sludge.
Rather, it addresses only the design features that
distinguish solid waste landfills receiving sludge from
those not receiving sludge. For information relating to
the design and operation of an MSW landfill, consult
U.S. EPA, 1993b.
7.6.1 Sludge/Solid Waste Mixture
In a sewage sludge/refuse mixture operation, sludge is
delivered to the working face of the landfill where it is
mixed and buried with the solid waste. At codisposal
sites, some sludge handling difficulties arise because
the sludge is more liquid in nature than the solid waste.
These difficulties include the following:
• The sludge is difficult to confine at the working face.
• Equipment slips and sometimes becomes stuck in
the sludge while operating at the working face.
These difficulties can be minimized if proper planning is
employed to control the quantity of sludge received at
the solid waste landfill. Every effort should be made not
to exceed the absorptive capacity of the refuse. The
maximum allowable sludge quantity will vary, primarily
depending on the quantity of solid waste received and
the solids content of the sludge. Table 7-13 presents
some design considerations for codisposal landfills. This
table includes suggested bulking ratios for sludge/refuse
mixtures at various sludge solids contents, but determina-
tions should be made on a site-by-site basis using test
operations. It should be noted that any sludge disposed
of in an MSW landfill must pass the paint filter liquids
test (Figure 7-23), as discussed in Section 3.4.3.
A second planning and design consideration for sludge/
solid waste mixture operations concerns leachate con-
trol. The impact of sewage sludge receipt on leachate
at MSW landfills is highly site specific. Generally, in-
creased leachate quantities should be expected.
Leachate control systems may have to be designed or
modified accordingly.
While sludge might be expected to degrade leachate
quality in an MSW landfill, a 4-year landfill simulator
study (Stamm and Walsh, 1988) evaluating codisposal,
municipal refuse-only disposal, and sludge-only dis-
posal found that codisposal had the least detrimental
effect on leachate quality (Table 7-14), with the bulk of
contamination being released approximately 1 year
sooner than sludge-only or solid waste-only configura-
tions. Codisposal also enhanced the decomposition
process as measured by methane generation. Codis-
posal test cells generated methane much sooner than
the refuse-only cell in this study. This is significant be-
cause methane collection and treatment is much more
effective in the early life of a landfill as compared to after
its closure.
126
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Landfill
• Spreading
• Covering
• Compacting
Sludge,
Input
. f
Dewatering
•
('
Truck
Transport
Figure 7-22. Landfill codisposal.
Table 7-13. Design Considerations for Codisposal Operations
Design
Parameter Consideration
Method
Bulking ratio Sludge/refuse mixture
Sludge/soil mixture
Bulking
agent
Refuse
Soil
Sludge solids
content
10-17%
17-20%
20%
20%
Bulking ratio
6 tons refuse :1
5 tons refuse : 1
4 tons refuse : 1
1 soil : 1 sludge
wet ton sludge
wet ton sludge
wet ton sludge
1 ton = 0.907 Mg
Paint Filter
Funn
•Ring Stand
<•—Graduated Cylinder
Figure 7-23. Paint filter test apparatus (U.S. EPA, 1993).
127
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Table 7-14. Various Average Leachate Values for Codisposal, Refuse-Only, and Sludge-Only Test Cells Averaged Over 4 Years
(Stamm and Walsh, 1988)
Par-meter Codisposal*
COD (mg/L)
TOC (mg/L)
PH
Volatile Acids (tng/i)
Volatile Solids (mg/L)
Specific .Volume . (L/kg/mo. )
2,889
903
7.1
868
2,171
0.03
Refuse-Only*
22,453
4,640
•6.4
7,434
7,659
0.03
Sludge-Only*
2.258
737
6.2
.1,213
5.555
0.07
* Average of Cell 1, 5, and 9.
+ Average of Cell 17 and 19.
r Average of Cell 21 and 23.
A third planning and design consideration is storage for
sludge received in off-hours. In many cases sludge is
delivered around the clock, while solid waste delivery is
confined to certain hours. Sludge storage facilities might
have to be installed to contain sludge overnight or over
weekends until sufficient refuse bulking is delivered.
7.6.2 Sludge/Soil Mixture and Sludge as
Daily Cover Material
The Solid Waste Disposal Facility Criteria require that
all owners and operators of MSW landfill units cover
disposed solid waste with 6 in. of earthen material at the
end of each operating day, or at more frequent intervals
if necessary, to control disease vectors, fires, odors,
blowing litter, and scavenging. A state may approve an
alternative material if the owner or operator demon-
strates that it controls disease vectors, fires, odors,
blowing litter, and scavenging without presenting a
threat to human health and the environment.
A sludge/soil mixture (in an approximately 1:1 ratio) may
be a suitable material for daily cover. Some landfills
have used sludge mixed with compost as daily cover
material (U.S. EPA, 1993a). In a sludge/soil mixture
operation, sludge is mixed with soil and applied as daily
cover or as cover over completed solid waste fill areas.
If a sludge/soil mixture operation is planned, an area
must be reserved at the planning/design stage for
sludge/soil mixing. This area must be of sufficient size
and have sufficient soil available for sludge bulking.
Information on suggested bulking ratios is included in
Table 7-13. The soils in the mixing area must also be
adequate to protect the ground water.
Sewage sludge also may be a suitable daily cover ma-
terial if it has a solids content of 50 percent or higher
and if it has undergone a process such as biological
stabilization to reduce the volatile solids content. Sludge
with these characteristics has the following advantages
as daily cover material (Lue-Hing et al., 1992):
• It has a high moisture absorption capacity, thereby
helping to control insects, rodents, and other vectors
that thrive under wet conditions.
• Like soil, it has a high odor-absorbing capacity. It also
reduces the emission of odorous gases from the
landfill by reducing the surface area of municipal solid
waste exposed to the atmosphere.
• Like soil, it acts as a physical barrier to control blow-
ing litter and improves the aesthetic appearance of
the landfill.
• If the volatile solids content of the sludge has been
reduced, it can reduce the fire hazard associated with
municipal solid waste landfills. Municipal sewage
sludge with a volatiles content of 50 to 55 percent
has a flash point of approximately 250°C, making it
suitable for use as a fire control agent at solid waste
landfills.
• It helps reduce the potential for leachate contamina-
tion of ground water and surface water.
Certain sludge-derived products have also been used
as alternative materials for daily cover at landfills.
Sludges can be treated by chemical fixation processes
using additives such as lime, cement kiln dust, fly ash,
and silicates to produce a suitable soil-like material.
Examples include the N-VIRO process, a patented pas-
teurization and chemical fixation process in which dewa-
tered sludge is blended with alkaline additives, cured,
and then aerated and windrowed. Another process,
CHEMFIX, is a proprietary chemical fixation process
using soluble silicates and silicate settling agents
blended with the sludge to produce a chemically and
physically stable solid material. These and similar fixa-
tion processes require the construction of sludge proc-
essing and curing facilities, possibly at significant capital
investment (U.S. EPA, 1993a).
To avoid workability problems when these sludge-de-
rived products are placed on the working face of a
128
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landfill, they must be cured and dried to a moisture
content of approximately 60 percent. At the proper mois-
ture content, they are reported to be lighter and easier
to spread than soil. An ammonia-like odor (usually re-
stricted to the working face) has been reported when
these products are initially placed on the working face.
To improve workability and control odors, the products
are sometimes blended with natural soil at a 1:1 ratio.
Problems with dust generation have also been reported
at some sites using sludge-derived products as daily
cover (U.S. EPA, 1993a).
7.6.3 Sludge/Soil Mixture and Sludge as
Final Cover Material
The Part 258 regulation requires that when an MSW
landfill has reached,the end of its useful life, it must
receive a final cover designed and constructed to have
a permeability less than or equal to the permeability of
the bottom liner system or the natural subsoils present,
or a permeability no greater than 1 x 10"5 cm/sec, which-
ever is less (Figure 7-24). The final cover must include
an infiltration layer composed of at least 18 in. of an
earthen material (such as clay) to minimize the flow of
water into the closed landfill. The cover must also con-
tain an erosion layer to prevent the disintegration of the
cover. The erosion layer must be composed of a mini-
mum of 6 in. of earthen material capable of sustaining
native plant growth.
EPA allows a state or tribe to approve an alternative
erosion layer design that provides equivalent protection
from wind and water erosion. This may include the use
of sludge/soil mixtures or sludge.
Sewage sludge may be suitable as material for the
erosion layer if it has a solids content greater than 20
percent and has undergone a process such as anaero-
bic digestion to reduce its volatile solids content. About
1 to 3 ft (0.3 to 0.9 m) of sludge is usually sufficient to
establish a vegetative cover. To prevent the sludge from
sliding down the side slopes, it should be mixed with the
surface soil at a 1:1 ratio (Lue-Hing et al., 1992).
7.7 Design Considerations for Dedicated
Surface Disposal Sites
DSD sites, including beneficial DSD sites on which
vegetation is grown, must be designed to meet the Part
503 Subpart C surface disposal requirements for
leachate collection (unless pollutant limits are met),
aquifer protection, and collection of surface water runoff.
Other important design considerations at DSD sites in-
clude determining the most appropriate sludge disposal
method to use, calculating the acceptable sludge dis-
posal rate, ascertaining land area needs, the site's prox-
imity to needed community infrastructure, and climatic
considerations. Design considerations for DSD sites are
discussed below, with the exception of the collection of
surface water runoff, which is discussed in Section 7.9.1.
7.7.1 Presence of a Natural Liner and Design
of a Leachate Collection System
A well chosen DSD site will be completely underlain with
a relatively impervious soil such as clay with a hydraulic
conductivity of 1 x 10"7 cm/sec or less, thus meeting the
Part 503 requirement for a liner as applicable to DSD
sites. If the DSD site owner is choosing to use this liner
to comply with Part 503 rather than by meeting pollutant
limits, then Part 503 requires that leachate be collected
at the site. If the DSD site contains both a liner and
leachate collection system, the sewage sludge at the
site is not required to meet the Part 503 pollutant limits
for surface disposal.
If the DSD site is not underlain with impervious soil, then
the sewage sludge at the DSD site must meet the
pollutant limits for arsenic, chromium, and nickel speci-
Erosion Layer
Min.6"Soil
or Soil/Sludge
Mixture
Infiltration Layer
Min. 18" Compacted Soil (1 x
10-5 cm/sec)
^ k
Existing Subgrade
Figure 7-24. Example of minimum final cover requirements (U.S. EPA, 1993).
129
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In addition to installing a leachate collection system to
comply with Part 503, a subsurface drainage system to
collect leachate may also need to be designed in areas
with a high ground-water table. In addition to increasing
the potential for ground-water contamination, a high
ground-water table may create serious problems for
sludge disposal at DSD sites, such as ponding, anaero-
bic soil conditions, or muddy surfaces.
Buried plastic pipe or clay tile, 10 to 20 cm (4 to 8 in.) in
diameter, is generally used for underdrains. Concrete
pipe is less suitable because of the sulphates that may
be present in leachate from soils on which sludge has
been disposed. Underdrains usually are buried 1.8 to
2.4 m (6 to 8 ft) deep, but can be as deep as 3 m (10 ft)
or as shallow as 1 m (3 ft). Spacing of drains typically
ranges from 15 m (50 ft) in clayey soils up to 120 m (400
ft) in sandy soils. Procedures for determining the proper
depth and spacing of drains can be found in other
publications, such as EPA's Process Design Manual for
Land Treatment of Municipal Wastewater (U.S. EPA,
1981), (U.S. Soil Conservation Service, 1972), and (Van
Schilfgaarde, 1974).
If a subsurface drainage collection system is installed
beneath the DSD site, the leachate collected from the
system may need to be treated and will need to be
properly stored and disposed or reused.
7.7.2 No Contamination of Aquifers:
Nitrogen Control at DSD Sites
The DSD owner must prove that ground-water is not
being contaminated, as specified in Part 503 based on
nitrate levels, through either a ground-water monitoring
program developed by a qualified ground-water scientist
or certification by a ground-water scientist, as discussed
in Chapter 4.
Several topographical and design conditions at a DSD
site will help in meeting the Part 503 regulatory require-
ment for controlling nitrates so the site does not contami-
nate an aquifer. These conditions include:
• No aquifer exists at potentially useful elevations.
• It can be shown that the volume of leachate contain-
ing nitrates reaching the aquifer is such a small per-
centage of the ground-water aquifer flow volume that
potential degradation is negligible.
• The local climate is arid with a high net evaporation
rate, and useful aquifers are deep.
• An impervious geological barrier, such as unfractured
bedrock or thick clay, lies between the DSD site and
a useful aquifer and serves as a liner, effectively
preventing significant volumes of leachate from per-
colating into the aquifer.
• A below-ground leachate collection system is con-
structed (e.g., drain tiles, well points, etc.) which collects
the leachate before it can percolate into the aquifer.
If none of the above possibilities is feasible, singly or in
combination, then the site is probably an inappropriate
location for a DSD site.
7.7.3 Methods for Disposal of Sewage
Sludge on DSD Sites
The choice of sludge disposal methods at DSD sites
are dictated by sewage sludge characteristics and often
by cost and/or aesthetics (e.g., odors or other commu-
nity concerns). The owner/operator of a DSD site has
a number of methods to choose from for sludge dis-
posal, including:
• Subsurface methods for liquid sludge, including (1)
subsurface injection or (2) plow or disc covering.
• Surface spreading of liquid sludge by tank trucks or
tank wagons.
• Spraying of liquid sludge.
• Surface spreading of dewatered sludge.
Each disposal method has advantages and disadvan-
tages which are discussed below. Tables 7-15a and
7-15b describe the methods, characteristics, and limita-
tions of disposing liquid sludge by surface methods and
subsurface methods. In all of the disposal techniques,
the sludge eventually becomes incorporated into the
soil, either immediately by mechanical means or over
time by natural means.
The technique used to apply sludge to the land can be
influenced by the means used to transport the sludge
from the POTW(s) to the DSD site. Commonly used
methods include:
• Same transport vehicle both hauls sludge from the
POTW to the DSD site and spreads sludge on the land.
• One type of transport vehicle, usually with a large
volume capacity, hauls sludge from the POTW to the
DSD site. At the DSD site, the sludge haul vehicle
transfers the sludge to an application vehicle, into a
storage facility, or both.
• Sludge is pumped and transported by pipeline from
the POTW to a storage facility at the DSD site.
Sludge is subsequently transferred from the storage
facility to the sludge application vehicle.
130
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Table 7-15a. Surface Spreading Methods and Equipment for Liquid Sludges (Cunningham and Northouse, 1981)
Meth*i
Tank truck
Farm tank wagon
Characteristic*
Capacity 500 to more than
2,000 gallon*; itii desirable
to have flotation tires; can be
used with temporary
irrigation set-up; with pump
discharge can achieve a
uniform tpreading rate.
Capacity 500 to 3,000 gallons;
it is desirable for wagons to
have flotation tires; can be
used with temporary
irrigation set-up; with pump
discharge, can achieve a
uniform spreading rate.
Topographical amd SeuoBal
LiBllatira*
Tillable land; not usable at
all times with row crops or
on very wet ground.
Tillable land; not usable at
all times with row crops or
on very wet ground.
Metric conversion factor 1 gal » 3.78 L
Table 7-15b. Subsurface Spreading Methods, Characteristics, and Limitations for Liquid Sludges (Keeney et al., 1975) for Liquid
Sludges (Cunningham and Northouse, 1981)
Mtthoi
Flexible irrigation hose with
plow or disc cover
Tank truck with plow or disc
cover
Farm tank wagon with plow
or disc cover
Subsurface injection
CharacUriitks
Use with pipeline or tank
truck with pressure discharge;
hose connected to manifold
discharge on plow or disc.
500-gallon commercial
equipment available; sludge
discharge in furrow ahead of
plow or disk mounted on
rear on four-wheel-drive
truck.
Sludge discharged into
furrow ahead of plow
mounted on tank trailer,
disposal of 170 to 225 wet
tons/acre; or sludge spread in
narrow band on ground
surface and immediately
plowed under, disposal of 50
to 120 wet tons/acre.
Sludge discharge into channel
opened by a chUeTtool
mounted on tank truck or
tool bar, disposal rate 25 to
50 wet tons/acre; vehicles
should not traverse injected
area for several days.
Topognphk mi Seasonal
timttattou
Tillable land; not usable on
very wet or frozen ground.
Tillable land; not usable on
very wet or frozen ground.
Tillable land; not usable on
very wet or frozen ground.
Tillable land; not usable on
very wet or frozen ground.
.Metric conversion factors: 1 gal =- 3.78 L, 1 ton/acre = 224 metric tons/hectare
7.7.3.1
Disposal Methods for Liquid Sludge at
DSD Sites
Subsurface Methods
Subsurface methods for disposal of liquid sludge at DSD
sites have a number of advantages over surface meth-
ods, including:
• Minimization of potential odor and other nuisance prob-
lems, and thus possibly better public, acceptance.
• Reduction of potential surface water runoff.
• Conservation of nitrogen (because ammonia volatili-
zation is minimized), which may be important if vege-
tation is grown onsite.
131
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Advantages of subsurface methods compared to spray-
ing include:
• Greater amounts of sludge can be disposed per
spreading activity
• Less visibility to the surrounding community
• Better disposal at DSD site perimeters
Nevertheless, subsurface methods have a number of
potential disadvantages compared to surface methods
for liquid sludge, including:
• Possibly more difficulty in achieving even distribution
of the sludge
• Higher fuel consumption costs than surface methods
Subsurface incorporation of liquid sludge can be done
in two basic ways—subsurface injection or plow or disc
covering. Figures 7-25 through 7-27 illustrate one type
of vehicle designed specifically for subsurface injection
of liquid sludge which consists of a tank truck with
special injection equipment attached. Tanks for the
trucks are generally available with 6,000, 7,500, and
11,000 I (1,600, 2,000, and 3,000 gal) capacities. Figure
7-28 shows another type of subsurface injection vehi-
cle—a tractor with a rear-mounted injector unit. Sludge
Figure 7-26. Tank truck with liquid sludge tillage injections
(courtesy of Rickel Mfg. Co.).
.TRACTOR AND INJECTION UNIT
Figure 7-25. Tractor and Injection unit.
132
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is pumped from a storage facility to the injector unit
through a flexible hose attached to the tractor. Discharge
flow capacities of 570 to 3,800 l/min (150 to 1,000 gpm)
are used. The tractor requires a power rating of 40 to 60 hp.
The plow or disc cover method involves discharging the
sludge into a narrow furrow from a tank wagon or flexible
hose linked to a storage facility through a manifold
mounted on a plow or disc; the plow or disc then imme-
diately covers the sludge with soil. Figures 7-29a and
7-29b depict a typical tank wagon with an attached plow.
These systems seem to be best suited for high loading
rates, (i.e., a minimum of 3.5 to 4.5 mt/ha [8 to 10 dry
T/ac]) of 5 percent slurry (Keeney et al., 1975).
Surface Methods
Surface spreading of liquid sludge involves spreading
without subsequent incorporation into the soil. Surface
spreading is less expensive than subsurface injection in
>.*•
Figure 7-29a. Tank wagon with sweep shovel injectors (Cun-
ningham and Northouse, 1981).
Figure 7-27. Tank truck with liquid sludge grassland injectors
(courtesy Rickel Mfg. Co.).
Figure 7-29b. Sweep shovel injectors with covering spoons
mounted on tank wagon (Cunningham and Nor-
thouse, 1981).
Figure 7-28. Tractor pulled liquid sludge subsurface injection unit connected to delivery hose (courtesy Briscoe Maphis Co.).
133
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terms of equipment and labor. But the DSD sites re-
viewed during preparation of this manual had experi-
enced problems when using surface spreading methods,
including odors, uneven distribution of sludge, clogging
of soil surface, and difficult vehicle access into the area.
Liquid sludge can be surface spread by vehicles
equipped with splash plates or a slotted T-bar. Selection
of either of these attachments should primarily be based
on whichever method results in the most uniform
spreading at an individual site. Figure 7-30 depicts a
tank truck equipped with splash plates, and Figure 7-31
depicts a tank truck with a rear mounted "T" pipe. For
these two methods, disposal rates can be controlled
either by valving the manifold or by varying the speed of
the truck. A much heavier spreading will be made from
a full truck than from a nearly empty truck unless the
speed of the truck or wagon advancing across the field
is steadily decreased to compensate for the steadily
decreasing hydraulic head (U.S. EPA, 1977).
Spray Method
Liquid sludge can also be sprayed on a site through
spray bars or nozzles. Spraying can be useful in dispers-
ing liquid sludge on DSD sites, particularly in remote
areas where public acceptance is less of a concern;
when sludge characteristics preclude using a sludge
storage lagoon onsite (e.g., because the sludge solids
at the bottom of the lagoon are difficult to remove even
Figure 7-30. Splash plates on back of tanker truck (U.S. EPA, 1978a).
Figure 7-31. Slotted T-bar on back of tanker truck (U.S. EPA, 1978a).
134
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with air mixing or other processes); or in colder climates
where freezing is a concern (U.S. EPA, 1984c).
Liquid sludge is readily dispersed by use of properly
designed spray equipment. By spraying the liquid
sludge under pressure, a more uniform coverage is
obtained. Sludge solids must be relatively small and
uniformly distributed throughout the sludge to achieve
uniform spray and to avoid system clogging.
The main component of a typical spray system is a
rotary sprayer (rain gun) to disperse the liquid sludge
over the. site. The sludge, pressurized by a pump, is
transferred from storage to the sprayer via a pipe sys-
tem. Both portable or permanent systems are available,
including (Loehr et al., 1979):
• Solid set, buried or above-ground
• Center pivot
• Side roll
• Continuous travel ,
• Towline laterals
• Stationary gun
• Traveling gun
Aii the systems listed, except for the buried solid set
system, are designed to be portable. Main lines for
systems are usually permanently buried, providing pro-
tection from freezing weather and heavy vehicles.
The proper design and operation of spray systems for
liquid sludge requires thorough knowledge of the com-
mercial equipment available and its adaptation to use
with liquid sludge. The sludge spray systems in use are
generally associated with DSD sites. It is beyond the
scope of this manual to present engineering design
data; qualified spray system engineers and experienced
spray system manufacturers should be consulted. Fig-
ures 7-32 and 7-33 illustrate two of the spray systems
available.
7.7.3.2 Disposal Methods for Dewatered Sludge
at DSD Sites
The spreading of dewatered sludge (20 percent solids
or more) is similar to that of solid or semisolid fertilizer,
lime, or animal manure. The dewatered sludge can be
spread with bulldozers, front end loaders, graders, or
box spreaders, and then incorporated into the soil by
plowing or discing. The box spreader is commonly used,
but the other types of equipment are often used for high
sludge spreading rates typical of DSD sites. Dewatered
sludge cannot be pumped or sprayed. The spiked tooth
harrows used for normal farming operations may be too
light to adequately bury the sludge; heavy-duty mine
disks or disk harrows may be required.
The principal advantages of using dewatered sludge
include reduced sludge hauling and storage costs and
higher sludge disposal rates (compared to liquid sludge)
per pass of equipment. Potential disadvantages of dis-
posing dewatered rather than liquid sludge at DSD sites
include the need for substantial modification of conven-
tional spreading equipment and more equipment re-
pairs, compared to many liquid sludge systems.
Figures 7-34 and 7-35 illustrate the specially designed
trucks used to spread dewatered sludge. For small
quantities of dewatered sludge, tractor-drawn conven-
tional farm manure spreaders may be adequate (Loehr
Figure 7-32. Venter pivot spray application system (Valmont Ind. Inc.).
135
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Figure 7-33. Traveling gun sludge sprayer (Lindsay Mfg. Co.).
Figure 7-34. 7.2 cubic yard dewatered sludge spreader (Big Wheels, Inc.).
et al., 1979). Surface spreading of dewatered sludge on
tilled land is usually followed by incorporation of the
sludge in the soil. Standard agricultural discs or other
tillage equipment pulled by a tractor or bull dozer can
incorporate liquid or dewatered sludge into soil, such as
the disk tiller, disk plow, and disk harrow shown in
Figures 7-36 and 7-37 (U.S. EPA 1978b).
7.7.3.3 Disposal Methods Not Recommended
Land spreading of sewage sludge by gravity irriga-
tion/flooding has generally not been successful where
attempted and is discouraged by regulatory agencies
and experienced designers. Problems with this method
include difficulty in achieving uniform sludge spreading
136
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Figure 7-35. Large dewatered sludge spreader {BJ Mfg. Co.).
Figure 7-36. Example of disc tiller.
rates; clogging of soil pores; and tendency of the sew-
age sludge to turn septic with resulting odors.
sewage sludge to DSD sites, as defined in this manual
and in Part 503, is limited by the following factors:
7.7.4 Sludge Disposal Rates at DSD Sites
Well managed DSD projects can be environmentally
acceptable even with high disposal rates if properly
sited, designed, and operated. The disposal rate of
• Part 503 pollutant limits in sewage sludge for sur-
face disposal sites if the site does not have a liner
and leachate collection system. Representative sam-
ples of sewage sludge must be tested for arsenic,
chromium, and nickel as required by Part 503 (see
137
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Figure 7-37. Example of disk plow.
Chapter 3) if the site does not have a liner and
leachate collection system.
If monitoring results show that the sludge meets Part
503 pollutant limits, or if a liner and leachate collection
system are onsite, then the other factors listed below
should then also be considered.
• The rate of sludge which can be disposed during
each spreading activity while still maintaining aerobic
conditions in the soil. The method of sludge disposal,
soil drainage, soil characteristics, sludge moisture con-
tent, and climatic conditions all influence this factor.
• The number of days during the year when sludge can
be disposed, as dictated by weather conditions, abil-
ity of the sludge spreading equipment to operate with
existing soil conditions, and equipment breakdown
and maintenance requirements.
• Evaporation rates of sludge liquids.
Annual sludge disposal rates at DSD sites range from
50 to 2,000 T/ac. The higher disposal rates are practiced
at DSD sites which:
• Receive dewatered sludge.
• Mechanically incorporate the sludge into the soil.
• Have relatively low precipitation.
• Are not faced with problems of leachate contamination
of ground water from site conditions or project design.
A conservative approach for calculating sludge disposal
rates is to match sludge disposal and net soil evapora-
tion rates. Sludge disposal will generally be intensive
during warm and dry periods and reduced during wet or
cold periods.
Net soil evaporation is calculated by the use of:
EN = ES - P
EN = (fxEL)-P (Eq. 7-1)
Where:
EN = net soil evaporation
Es = gross soil evaporation
EL = gross lake evaporation
P = precipitation
f = factor expressing the relationship of soil and
lake evaporation (dimensionless)
Typically, gross soil evaporation in an area is estimated
as a fraction (e.g., f = 0.70) of the lake evaporation.
Estimates can be obtained from local agricultural infor-
mation services. Table 7-16 illustrates the calculation of
net soil evaporation on a monthly basis for Colorado
Springs, Colorado (Brown and Caldwell, 1979).
Having estimated net soil evaporation (EN) for each
month, the sludge disposal rates on a monthly basis are
calculated by matching the moisture in the disposed
sludge against EN, as shown below:
EN x TS xC
100-TS
(Eq. 7-2)
Where:
RM = monthly sludge disposal rate (dry mt/ha/mo or
dry T/ac/mo)
EN = net soil evaporation (cm/mo or in./mo)
TS = total solids content of the sludge ( percent) by
weight
C = conversion factor which equals 100 mt/cm or
113.3T/in.
138
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Table 7-16. Net Monthly Soil Evaporation at Colorado Springs, Colorado (Brown and Caldwell, 1979)
Gross Soil Net Soil
Month Evaporation (cm)* Precipitatjon (cm)
Evaporation (cm)
January
February
March
April
May
June
July
August
September
October
November
December
Annual
.
.
9.16
11.45
13.55
14.69
12.43
9.58
7.34
_
-
78.20
1.80
1.85
3.96
4.85
5.44
5.49
7.62
5.89
3.94
2.82
2.41
1.70
47.78
_
-
-
4.31
6.01
8.06
7.07
6.54
5.64
4.52
-
-
42.15
Estimated based on 70 percent lake evaporation.
t Gross soil evaporation less precipitation.
# 1 in * 2.54 cm.
Table 7-17 shows monthly sludge disposal rates for the
Colorado Springs site based on a sludge with a 4.85
percent solids content and the net monthly soil evapo-
ration rates shown in Table 7-16. Sample calculations
for April would be:
Metric
English
4.31 x 4.85x100
100-4.85
= 22 m/ha
1.70x4.85x113.3
100-4.85
= 9.8 T/ac
Referring to Table 7-17, an annual average total of 215
mt/ha (95.8 T/ac) dry weight of sludge could be disposed
at this site based on net soil evaporation.
The use of net soil evaporation as a basis for calculating
sludge disposal rates at DSD sites is conservative since
it makes no allowance for moisture removal from the
sludge through infiltration into the soil. If infiltration is
allowed, sludge disposal rates at DSD sites can be
calculated by the following equation:
(EN + l)xTSxC
M~ 100-TS
Where:
I = infiltration rate (cm/mo or in./mo)
all other terms as in previous equations
7.7.5 Drying Periods Between Sludge
Spreading Activities
Drying (rest) periods between each sludge spreading
activity allow the soil to return to its natural aerobic
condition. Disposal should be scheduled to prevent ex-
cessive moisture in the soil for long periods and to
minimize odors and the breeding of vectors.
Table 7-17. Monthly Sludge Disposal Rates at Colorado
Springs, Colorado, DSD Site (Brown and
Caldwell, 1979)
Monthly Application Rate
Month
(dry mt/ha)t
(dry T/acV
January
Feoruary
March
April
May
June
July
August
September
October
November
December
m
-
•
22. 0
30.7
41.1
36.1
33.4
28.8
23.1
.
-
_
-
-
9.8
13.7
18.3 '
16.1
14.8
12.8
10.3
-
'
Annual
215.0
95.8
* Total solid content in the sludge is assumed to be 4.85 percent.
t Using Equation (7-2) and data from Table 7-16.
It is difficult to provide exact guidelines for the length of
the drying period because numerous factors are in-
volved, including:
• Quantity and moisture content of sludge disposed.
• Method of sludge disposal.
• Net soil evaporation rate and precipitation occurring
during the days following disposal.
• Soil texture and infiltration rate.
Generally, if dewatered sludge is disposed and/or the
sludge is incorporated into the soil during disposal, dry-
ing periods between each spreading activity can be
short (2 to 3 days), providing the weather is favorable.
When liquid sludge is spread to the soil surface without
soil incorporation, the drying periods should be longer
139
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(5 to 20 days), depending upon the quantity applied,
topography, soil properties, and weather. Figure 7-38
shows suggested periods between each sludge spread-
ing activity as a function of the type of sludge (liquid or
dewatered), whether the sludge is incorporated into the
soil, and disposal rate. This figure is based on experi-
ence at a limited number of DSD sites reviewed and is
provided for general guidance only.
Aerobic conditions in the soil are more easily maintained
by lighter disposal of sludge at more frequent intervals.
For example, referring to the upper curve in Figure 7-38
for liquid sludge that is not incorporated into the soil,
disposal of 11 mt/ha (5 T/ac) at 7-day intervals are
generally preferable to disposal of 31 mt/ha (14 T/ac) at
20-day intervals. The heavier sludge disposal is more
likely to cause anaerobic soil conditions conducive to
odors and vector breeding.
7.7.6 Land Area Needs
Availability of sufficient land area is an essential consid-
eration in selecting a DSD site. Oftentimes, DSD sites
are located on land owned by a municipality. The high
sludge disposal rates at DSD sites minimize land re-
quirements (compared to land application options, such
as spreading sludge on agricultural land) by maximizing
sludge disposal rates per hectare.
Land area needs for a DSD site include land needed for
sludge disposal, sludge storage, buffer areas, surface
runoff control, and supporting facilities. Each of these
needs is discussed below. The prudent designer will
incorporate appropriate factors into the design to allow
for possible future expansion.
7.7.6.1 Land Needed for Sludge Disposal
Once the acceptable sludge disposal (spreading) rate
has been determined (as discussed in Section 7.7.5
above), a simple calculation can be used to define the
area needed for sludge disposal. The calculation in-
volves dividing the annual disposal/spreading rate into
the total estimated quantity of sludge (both present and
future) to be disposed annually, as shown below:
Area required =
Maximum estimated amount of sludge be disposed of annually (dry weight)
Annual disposal/spreading rate (dry weight/unit area)
7.7.6.2 Land Needed for Sludge Storage
Sludge storage is virtually always required at DSD sites
because adverse weather or other factors prevent the
continuous spreading of sludge at the site. Storage may
be located at the POTW, at the DSD site, or both. At a
minimum, the sludge storage facilities should have suffi-
cient capacity to retain all sludge generated during non-
spreading periods. Liquid sludge is typically stored in
lined lagoons or metal tanks. Dewatered sludge is typi-
cally stored by mounding in areas protected from runoff.
Odor controls are often needed for sludge lagoons, as
20
15 -
«
gs
S.1-
jd eo
in"0
six:
3
5 -
10
IB
20.
Tons/acre of sludge disposed, dry weight, each spreading activity
Metric conversion - 0.446 tons/acre = 1 metric ton/ha
Figure 7-38. ^Siested drying days between sludge activities at DSD sites for average soil conditions and periods of net evaporation
140
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discussed in the section on "Aesthetics at DSD Site" in
Chapter 9.
If sludge is stored for less than two years, the area is
not considered to be final disposal and is not covered
under Part 503. If, however, sludge is placed on an area
of land for more than two years, that land area is con-
sidered a final surface disposal site, and, in addition to
the area on which sludge is spread on the land, this
"storage" area must also meet the Part 503 surface
disposal requirements. Often the relevant regulatory
agency will stipulate the minimum number of days for
which sludge storage must be provided at a site (e.g.,
one-month or two-month storage).
One method for estimating the storage capacity needed
for sewage sludge involves estimating the maximum
volume of sewage sludge to be disposed each day at
the DSD site, the percentage of solids the sludge
contains, and the number of storage days to be pro-
vided. These estimations should include climatic and
soil considerations (discussed later in this chapter) and
a s'afety factor. The project designer should increase the
minimum storage requirement by a safety factor of 20 to
50 percent to cover years with unusual weather and
other contingencies. An example calculation for this
approach is:
Assuming:
• The average rate of dry sludge solids to be disposed
at the DSD site is 589 kg/day (1 ,300 Ib/day).
• The sewage sludge contains 5 percent solids on the
average.
• 100 days of storage are to be provided.
589kg/day = „
0.05<% solids) -••
of liquid sludge to
be stored.
11,778 kg/day = 11,778 liters (l)/day (3,118
gal/day) of liquid sludge to
be stored.
11,788 I/day x 100 days = 1.2 mil I (312,000 gal) of
storage required.
A more sophisticated method of calculating sludge stor-
age needed is to prepare a mass flow diagram of pro-
jected cumulative sludge generation and disposal at the
DSD site, as shown in Figure 7-39. The figure shows
that the minimum sludge storage requirement for the
system is approximately 1.2 x 106 gal (4.54 x 106 I),
which represents 84 days of sludge volume storage.
Even more accurate approaches can be used to calcu-
late required sludge storage volume. For example, if
open lagoons are used for sludge storage, the designer
can calculate volume additions resulting from precipita-
tion and volume subtractions resulting from evaporation
from the storage lagoon surface.
Once the necessary storage volume has been estab-
lished, the land area required for either liquid sludge
lagoons or dewatered sludge stockpiles can be deter-
mined based on depth, height, freeboard, berm con-
struction area, etc. As a rough approximation, the land
area required equals three times the volume of the
sludge to be stored divided by the depth (or height) of
the material stored. For example, assume that one mil-
lion L (35,310 ft3) of liquid sludge storage is required and
the liquid depth of the lagoon is 3 m (9.8 ft). The approxi-
mate area required equals 1,000 m2 (10,800 ft2).
Storage capacity can be provided by:
• Lagoons
• Tanks (open top or enclosed)
• Digesters
• Stockpiles
These sludge storage methods are summarized briefly
below. For a more detailed discussion on sewage sludge
storage options, see EPA's Process Desit/n Manual for
Sludge Treatment and Disposal (U.S. EPA, 1979).
Lagoons are usually the least expensive way to store
sludge. With proper design, lagoon detention will also
provide additional stabilization of the sludge and reduce
pathogens. Several types,of lagoons have been used
for sludge storage, including:
• Facultative sludge lagoons
• Anaerobic liquid sludge lagoons
• Aerated storage basins
• Drying sludge lagoons
Various types of tanks also can be used to store sludge.
In most cases, tanks are an integral part of the sludge
treatment processes of the POTW and their design
includes storage capabilities. Three common types of
tanks used for sludge storage include:
• Imhoff and community septic tanks
• Holding tanks
• Unconfined hoppers and bins
Many sewage treatment plants do not have separate
sludge retention capacity but rather rely on portions of
the digester volume for storage. When available, an un-
heated sludge digester may provide short-term storage
capacity. In anticipation of periods when sludge cannot
be disposed on the DSD site, digester supernatant with-
drawals can be accelerated to provide storage for sev-
eral weeks of sludge volume (U.S. EPA, 1978a).
141
-------
13
O
6.0-t
5.0'
_1 4..0-
U
UJ
a
a
> 3.fl-
at
=i
JU 2.0-
<
SC
3
o i .0-
TOTAL ANNUAL SLUDGE
VOLUME GENERATED
LINE A
CUM XILATIVE SLUDGS
VOLUME GENERATED *x'
BY THE POTW
SLUDGE
STORAGE
VOLUME
L
LINEB
CUMULATIVE SLUDGE
VOLUME SPREAD ON
THE DSD SITE (S)
LINE C. SAME SLOPE
AS LINE A, LOCATE
TANGENT TO LINE B
M J
MONTHS
METRIC CONCESSION
: GAL » 3.78 L
Figure 7-39. Example of mass flow diagram using cumulative generation and cumulative sludge spreading to estimate storage
requirements at a DSD site.
Stockpiling is a temporary storage method for sludge
that has been stabilized and dewatered or dried to a
concentration (about 20 to 60 percent solids) suitable for
mounding with bulldozers or loaders. The sludge is
mounded into stockpiles 2 to 5 m (6 to 15 ft) high,
depending on the quantity of sludge and the available
land area. Periodic turning of the sludge helps to pro-
mote drying and maintain aerobic conditions. The proc-
ess is most applicable in arid and semiarid regions, unless
the stockpiles are covered to protect against rain. Enclo-
sure of stockpiles may be necessary to control runoff.
7.7.6.3 Land Needed for Buffer Zone
If the DSD site is meeting the Part 503 pollutant limits
for arsenic, chromium, and nickel at surface disposal
sites (rather than having a liner and leachate collection
system onsite to meet this Part 503 requirement), then
the distance of the actively used portions of the DSD site
from the property boundary will determine the specific'
pollutant limits that must be met (see Chapter 4).
The desired width of an acceptable buffer zone will vary,
depending on surrounding land use and the potential for
odor, dust, and noise resulting from the site. A minimum
buffer of 150 m (500 ft) is suggested around any DSD
site. A minimum buffer of 600 m (2,000 ft) is suggested
around DSD sites when one or more of the following
conditions will exist:
• Liquid sludge is stored at the site in open lagoons.
• Liquid sludge is spread on the soil surface and is not
quickly incorporated by discing.
• Liquid sludge is sprayed using a wide coverage spray
device.
• Residential dwellings or other heavily used public
areas are adjacent to the DSD site.
• Sludge disposal rates are high and it is anticipated
that anaerobic soil conditions will periodically result.
While difficult to quantify, the desirable width of a buffer
zone is also a function of the size of the operation (e.g.,
142
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volume of sludge disposed and the disposal area). The
larger the operation, the more buffer area is desirable
simply because the magnitude of potential nuisance to
surrounding property is greater.
7.7.7 Proximity to Community Infrastructure
Another important consideration in designing a DSD site
is its location relative to local infrastructure, including:
• Availability of a sewerage system to manage surface
runoff and/or leachate.
• Proximity to a treatment plant to maintain reasonable
sludge transportation costs.
• Accessibility to transport (e.g., roads and/or pipe-
lines).
7.7.8 Climate Considerations
Information on local climatic conditions is used in many
aspects of the DSD site design, including:
• Designing surface runoff collection, storage, and con-
trol structures.
• Determining necessary sludge storage capacity.
• Determining the area requirements for sludge
spreading.
• Determining any necessary leachate collection and
storage systems.
The designer should obtain the following historical cli-
matic information for the past 20 years:
• Precipitation, by month and year (average and maxi-
mum).
• 25-year storm intensity (for which control is required
by Part 503); also 50- and 100-year storms.
• Evaporation rate from water surface, by month and
year (average and minimum).
• Annual number of days of precipitation over 0.3 cm
(0.1 in) (average and maximum).
• Annual number of days below freezing (average and
maximum).
In addition, it is useful to know the local evaporation rate
from soils (usually about 70 percent of the rate from
water surfaces). This information may be available from
local university agricultural extension services or federal
agencies. Generally, a site located in a temperate, arid
climate is preferable for its high net evaporation.
7.7.9 Design Considerations At Beneficial
DSD Sites
Some DSD sites are considered beneficial DSD sites
because vegetation is grown on the site. The Part 503
regulation states that no crop production or grazing can
be conducted at any surface disposal site, including
beneficial DSD sites, unless the owner/operator can
demonstrate to the permitting authority that, through
management practices, public health and the environ-
ment will be protected from any reasonably anticipated
adverse effects of pollutants in sewage sludge when
crops are grown or animals are grazed. Growing vege-
tation at a beneficial DSD site has both major advan-
tages and disadvantages, as discussed in Table 7-18.
Beneficial DSD sites are discussed further in Chapter 9.
7.8 Environmental Safeguards at
Surface Disposal Sites
Ground-water protection is the most difficult and costly
environmental control measure required at many sew-
age sludge surface disposal sites. Additionally, contami-~
nation of surface water and methane gas buildup must
be avoided. Design concepts that minimize or prevent
adverse environmental impacts from surface drainage
and methane gas migration at surface disposal sites are
presented below. Other environmental controls are dis-
cussed in Chapter 8, Operations, since their control is
more a function of operation than design.
7.8.1 Leachate Controls
Leachate can be generated simply from the excess
moisture in the sewage sludge received at a surface
disposal facility. Rainfall on the surface of the disposal
unit can add a limited amount of water to the interred
sludge. The surface of the disposal unit should be
Table 7-18. Advantages and Disadvantages of Dedicated
Beneficial Use Sites
Advantages 1. If surface soil is "tight" and drains poorly,
the plant root structure may improve soil
drainage.
2. Plants will enhance water removal through
evapotranspiration. •
3. Plants will help to reduce surface runoff
volume from precipitation.
4. Plants will take up a portion of the
nitrogen, metals, and other sludge
constituents applied by incorporating them
during growth. If the plants are harvested
and used or disposed in a controlled
manner, the constituents incorporated in
the plants are removed from the site.
5. The DSD site will more closely resemble a
normal farming operation and be more
visually pleasing to the public.
6. Some of the sludge nutrients will be
recycled into vegetation and may serve as
a positive public relations factor to many
citizens.
7. Harvesting of the plants and their sale may
provide a monetary return.
143
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Table 7-18. Advantages and Disadvantages of Dedicated
Beneficial Use Sites (continued)
Disadvantages 1. Sludge spreading scheduling is more
complex since it usually must operate
around the seeding, cultivation, and
harvesting operations. Planted areas may
be "off limits" for high rate sludge disposal
during many months, often the best
months for sludge disposal from an
operations viewpoint.
2. Planting, cultivation, and harvesting of .
plants can be labor and equipment
intensive. Capital equipment and operating
costs are increased over those for a DSD
site that does not grow and harvest
vegetation. Management is more complex
since agronomic considerations are added
to the primary mission of sludge
management.
3. The area required for a DSD site may be
larger with vegetation involvement than for
a project with no vegetation.
4. Planted areas attract animals that could
become a nuisance or serve as vectors.
5. Planted areas may result in more
unauthorized public entry, e.g., children
climbing fences.
6. Harvested plants may contain metal
concentrations too high for human or
animal consumption necessitating
controlled disposal.
7. After years of heavy sludge disposal, the
soil may become phytotoxic to plants
effectively ending any potential for
agricultural operations at the site.
sloped enough to cause most of the rainfall to drain.
Other stormwater runoff must be diverted around the
disposal unit, and the unit must be located above
historically high ground-water elevations. These positive
controls will minimize the quantity of leachate generated.
Leachate may enter into the water system essentially
through two pathways:
• Percolation of the leachate, laterally or vertically,
through soil into the ground-water aquifers.
• Runoff of leachate outcroppings into surface waters.
Careful site selection and attention to design considera-
tions can prevent or minimize leachate contamination of
ground water and surface water. The control of leachate
may be accomplished through:
• Natural conditions and attenuation (Section 6.4 and 6.5).
• Imported soils or soil amendments used as liners
and/or cover (Section 7.5.6.1).
• Membrane liners (Section 7.5.6.2).
• Collection and treatment (Section 7.5.7).
7.8.2 Run-on/Runoff Controls
The purpose of a run-on control system is to collect and
redirect surface waters to minimize the amount of sur-
face water entering active sewage sludge units. Run-on
control can be accomplished by constructing berms and
swales above the filling area that will collect and redirect
the water to the stormwater control structures.
Surface water management also is necessary at surface
disposal sites to minimize erosion damage to earthen
containment structures. Design of a surface water
management system requires a knowledge of local
precipitation patterns, surrounding topographic features,
geologic conditions, and facility design. Surface water
management systems do not have to be expensive or
complex to be effective. The equipment and materials
used for construction of the surface water management
system are the same as those used for general earth-
work and foundation construction. Construction may in-
clude excavation of a series of shallow channels to
direct surface water flow, or in some cases, installation
of basins to retain rainfall accumulation from sudden,
intense storms. Surface water management systems
are required for all surface disposal sites. This section
provides a general discussion of design criteria for those
systems and describes the types of system compo-
nents. For more information on the materials and con-
struction techniques that may be employed to control
run-on/runoff at surface disposal sites, see the reference
U.S. EPA(1988a).
The management practices of the Part 503 regulation
require the owner/operator of surface disposal units to
operate and maintain runoff and run-on management
systems capable of collecting and controlling at least the
water volume resulting from a 24-hour, 25-year storm.
7.8.2.1 Design Overview
The standard design approach for a surface water con-
trol system is to: ,
• Identify the intensity of the design storm.
• Determine the peak discharge rate.
• Calculate the runoff volume during peak discharge.
• Determine the control system design criteria and the
required capacity for the control systems.
• Design the control system.
Identify Design Storm
Information on the 24-hour, 25-year recurring storm can
be obtained from Technical Paper 40 Rainfall Frequency
Atlas of the United States for Durations from 30 Minutes
to 24 Hours and Return Periods from 1 to 100 years,
prepared by the Weather Bureau under the Department
of Commerce.
144
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Determining Peak Discharge Rate/Calculating Runoff
The two methods commonly recommended by EPA for
use in designing surface water management structures
are the Soil Conservation Service (SCS) method and
the rational method.
SCS Method. A method that is most often appropriate
for estimating run-on/runoff and peak discharge rate
from a storm's rainfall is the SCS method. This method
was originally designed to determine runoff volumes for
small agricultural watersheds where insufficient long-
term stream flow and precipitation data had been col-
lected, but where soil types, topography, vegetative
cover, and agricultural practices had been documented.
The SCS method estimates runoff volume from accumu-
lated rainfall and then applies the runoff volume to a
simplified triangular unit hydrograph for peak discharge
estimation and total runoff hydrograph (U.S. EPA,
1993b). A discussion of the development and use of this
method is available in the reference U.S. Department of
Agriculture, Soil Conservation Service (1986).
national Method. The rational method can be applied
when determining peak discharge rates for significantly
urbanized areas with largely impervious surface covers.
The method is based on the premise that maximum
runoff resulting from steady, uniformly intense precipita-
tion will occur when the entire watershed, upstream of
the site location, contributes to the discharge (U.S. EPA,
1985a). The method generally is used for areas of less
than 200 acres. A discussion of the rational method can
be found in U.S. EPA (1988a).
Control System Structures
Surface water management plans can incorporate sev-
eral structures, both temporary and permanent, into the
system design. Table 7-19 provides a list of the most
frequently used structures.
Dikes/Berms. Dikes and berms are well-compacted
earthen ridges or ledges constructed immediately upslope
from or along the perimeter of the intended area of
protection. Atypical dike design is shown in Figure 7-40.
Dikes are intended to provide short-term protection of
critical areas by intercepting storm runoff and diverting
the flow to natural or man-made drainage channels,
man-made outlets, or sediment basins. Typically, dikes
and berms should be expected to maintain their integrity
for about 1 year, after which they should be rebuilt. Dikes
are generally classified into two groups: interceptor
dikes, designed to reduce slope length; and diversion
dikes, designed to divert surface flow and to reduce
slope length. Dikes can also prevent mixing of incom-
patible wastes and can reduce the amount of leachate
produced in a landfill cell by diverting the water available
to infiltrate the soil cover. Due to their temporary nature,
dikes and berms are designed for runoff from no. larger
than a 5-acre watershed (U.S. EPA, 1985b).
Swales, Channels, and Waterways. Channels are exca-
vated ditches that are generally wide and shallow with
trapezoidal, triangular, or parabolic cross sections. A
typical channel design is shown in Figure 7-41. Diver-
sion channels are used primarily to intercept runoff or
reduce slope length. Channels stabilized with vegetation
or stone rip-rap are used to collect and transfer diverted
water off site or to onsite storage or treatment. Applica-
tions and limitations of channels and waterways differ
depending upon their specific design (U.S. EPA, 1988a).
Swales are placed along the perimeter of a site to
keep offsite runoff from entering the site and to carry
surface runoff from a land disposal unit. They are distin-
guished from earthen channels by side slopes that are
less steep and have vegetative cover for erosion control
(U.S. EPA, 1985b).
The specific design for channels, swales, and water-
ways must consider local drainage patterns, soil perme-
ability, annual precipitation, area land use, and other
pertinent characteristics of the contributing watershed.
To comply with the Part 503 regulation, channels and
waterways should accommodate the maximum rainfall
expected in a 25-year period. Manning's formula for
steady uniform flow in open channels is used to design
channels and waterways (U.S. EPA, 1985b).
Terraces. Terraces are embankments constructed along
the contour of very long or very steep slopes to intercept
Table 7-19. Surface Water Diversion and Collection
Structures (U.S. EPA, 1988a)
Technology
Duration of Normal Use
Dikes and berms
Channels (earthen and CMP)
Waterways
Terraces and benches
Chutes
Downpipes
Seepage ditches and basins
Sedimentation basins
Temporary
Temporary
Permanent
Temporary and
permanent
Permanent
Temporary
Temporary
Temporary
Cut or fill slope
Flow
Existing ground
Figure 7-40. Typical temporary diversion dike (U.S. EPA, 1988a).
145
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Parabolic cross-section
Figure 7-41. Typical channel design (U.S. EPA, 1988a).
and divert flow of surface water and to control erosion
of slopes by reducing slope length. A typical terrace
design is shown in Figure 7-42. Terraces may function
to hydrologically isolate sites, control erosion of cover
materials on sites that have been capped, or collect
sediments eroded from disposal areas. For disposal
sites undergoing final grading, construction terraces
may be included as part of the site closure plan (U.S.
EPA, 1985b).
Chutes and Downpipes. Chutes and downpipes are
usually temporary structures that can play an important
role in preventing erosion while monofill and surface
impoundment covers are "stabilizing" with vegetation. A
typical chute design is shown in Figure 7-43. Chutes are
excavated earthen channels lined with non-erodible ma-
terials such as bituminous concrete or grouted rip-rap.
Downpipes are constructed of rigid piping or flexible
tubing and installed with prefabricated inlet sections. As
a general rule, chutes should not be used when hydrau-
lic heads are expected to be more than 18 ft (U.S. EPA,
1988a). Downpipes should not be used when the drain-
age basin is estimated to be larger than 5 acres (U.S.
EPA, 1985b).
Seepage Basins and Ditches. Seepage basins and
ditches are used to discharge water collected from sur-
face water diversions, ground-water pumpings, or
leachate treatment. They also may be used as part of
an in situ treatment process to force treatment reagents
into the subsurface. A typical seepage basin design is
shown in Figure 7-44. They are most effective in highly
permeable soils where recharge can occur. Typically,
they are used in areas with shallow ground-water tables.
Seepage ditches distribute water over a larger area than
achievable with basins. They can be used for all soil
where permeability exceeds about 0.9 in. per day (U.S.
EPA, 1985b).
A seepage basin typically consists of the actual basin, a
sediment trap, a bypass for excess flow, and an emer-
gency overflow. A considerable amount of recharge oc-
curs through the sidewalls of the basin, and therefore it
is preferable that these be constructed of pervious ma-
terial such as packed gravel (U.S. EPA, 1985b).
Ditch
Ditch
Figure 7-42. Typical terrace design (U.S. EPA, 1988a).
Sedimentation Basins. Sedimentation basins are used
to retard surface water flow such that suspended par-
ticulates can settle. Sedimentation basins serve as the
final step in the control of diverted, uncontaminated
surface runoff, prior to discharge. Atypical basin design
is shown in Figure 7-45. Basins are especially useful in
areas where surface runoff has a high silt or sand con-
tent. The major components include a principal and
emergency spillway, an anti-vortex device, and the ba-
sin. The principal spillway consists of a vertical pipe or
riser joined to a horizontal pipe that extends through the
dike and has an outlet beyond the impoundment. The
riser is topped by the anti-vortex device and trash rack,
which improves the flow of water into the spillway and
prevents floating debris from being carried out of the
basin (U.S. EPA, 1985b).
7.8.3 Explosive Gases Control
Under the Part 503 regulation, surface disposal sites
that cover active sewage sludge units (either daily or at
closure) must limit the concentration of methane gas in
the air in any structure within the site, and in the air at
the property line of the disposal site (see Section
7.2.1.3).
The accumulation of methane gas in surface disposal
structures can potentially result in fire and explosions
that can endanger employees, users of the disposal site,
and occupants of nearby structures, or cause damage
to containment structures. These hazards are prevent-
able through monitoring and through corrective action
146
-------
Top of earth dike and top of lining
Slope
varies, not steeper than 1.5:1
not flatter than 20:1
Undisturbed soil
or compacted fill
• Place layer of
,. ; sand for drainage
:'.'.'•;. .••,'"'• under outlet as
;. shown for full
--;":- ••''. width of structure
Figure 7-43. Typical paved chute design (U.S. EPA, 1988a).
Seepage basin
Bypass
Figure 7-44. Typical seepage basin design (U.S. EPA, 1988a).
•4-f/ Jl
ment tra
1
P t
* . -— --' • •
, . c
T
Overflow
Anti-vortex Device
Water Surface (design)
Emergency Spillway Crest
Anti-seep Collars
Pipe Conduit or Barrel
Principal Spillway
Free Outlet
EMBANKMENT
Figure 7-45. Typical sedimentation basin design (U.S. EPA, 1988a).
147
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should methane gas levels exceed specified limits in the
facility structures (excluding gas control or recovery sys-
tem components), or at the facility property boundary.
To implement an appropriate plan for routine monitoring
of methane in order to demonstrate compliance with
allowable methane concentrations, the characteristics of
gas production and migration at a disposal site should
be understood. See the reference U.S. EPA (1993b) for
a complete discussion of the characteristics of methane
gas production.
7.8.3.1 Gas Monitoring
To demonstrate compliance with the Part 503 regulation,
the owner/operator must sample air within facility struc-
tures where gas may accumulate and in soil at the
property boundary. Other monitoring methods may in-
clude: sampling gases from probes within the surface
disposal unit or from within the leachate collection sys-
tem; or sampling gases from monitoring probes installed
in soil between the surface disposal unit and either the
property boundary or structures where gas migration may
pose a danger. A typical gas monitoring probe installa-
tion is depicted in Figure 7-46 (U.S. EPA, 1993b).
The frequency of monitoring should be sufficient to de-
tect methane gas migration based on subsurface condi-
tions and the changing conditions within the disposal
unit such as partial or complete capping, unit expansion,
gas migration control system operation or failure, con-
struction of new or replacement structures, and changes
in landscaping or land use practices. The rate of meth-
ane gas migration as a result of these anticipated changes
and the site-specific conditions, provides the basis for
establishing a monitoring frequency (U.S. EPA, 1993b).
The number and location of gas probes is also site
specific and highly dependent on subsurface conditions,
land use, and location and design of facility structures.
Monitoring for gas migration should be within the more
permeable strata. Multiple or nested probes are useful
in defining the vertical configuration of the migration
pathway. Structures with basements or crawl spaces are
more susceptible to landfill gas infiltration. Elevated
structures are typically not at risk (U.S. EPA, 1993b).
Measurements are usually made in the field with a portable
methane meter, explosimeter, or organic vapor analyzer.
Gas samples also may be collected in glass or metal
containers for laboratory analysis. Instruments with scales
of measure in "percent of LEL" can be calibrated and
used to detect the presence of methane. Instruments of
the hot-wire Wheatstone bridge type (i.e., catalytic com-
bustion) directly measure combustibility of the gas mix-
ture withdrawn from the probe. The thermal conductivity
type meter is susceptible to interference as the relative
gas composition—and, thus, the thermal conductivity—
changes. Field instruments should be calibrated prior to
PVC caps with
petcocks
Protective casing
with lock
BentonKe ioil seal
BentonKe seal
11nch PVC pipe
1/2 inch PVC pipe
11nch perforated
PVC pipe
Gravel backfill
Bentonlte seal
Sand and gravel
Probe screen
Figure 7-46. Typical gas monitoring probe (U.S. EPA, 1993b).
measurements and should be rechecked after each
day's monitoring activity (U.S. EPA, 1993b).
Laboratory measurements with organic vapor analyzers
or gas chromatographs may be used to confirm the
identity and concentrations of gas. In addition to meas-
uring gas composition, other indications of gas migration
may be observed. These include odor (generally described
as either a "sweet" or a rotten egg [hydrogen sulfide, or
H2S] odor), vegetation damage, septic soil, and audible
or visual venting of gases, especially in standing water.
Exposure to some gases can cause headaches and
nausea.
If methane concentrations are in excess of 25 percent
of the LEL in facility structures or exceed the LEL at the
property boundary, the danger of explosion is imminent.
Immediate action must betaken to protect human health
from potentially explosive conditions. All personnel
should be evacuated from the area immediately. Venting
the building upon exit (e.g., leaving the door open) is
desirable but should not replace evacuation procedures.
See Section 10.4.4 for additional information on meth-
ane monitoring.
7.8.3.2 Gas Control Systems
Gas from covered surface disposal units may vent natu-
rally or be purposely vented to the atmosphere by verti-
148
-------
cal and/or lateral migration controls. Systems used to
control or prevent gas migration are categorized as
either passive or active systems. Passive systems pro-
vide preferential flow paths by means of natural pres-
sure, concentration, and density gradients. Passive
systems are primarily effective in controlling convective
flow and have limited success controlling diffusive flow.
Active systems are effective in controlling both types of
flow. Active systems use mechanical equipment to direct
or control landfill gas by providing negative or positive
pressure gradients. Suitability of the systems is based
on the design and age of the surface disposal unit, and
on the soil, hydrogeologic, and hydraulic conditions of
the facility and surrounding environment. Because of
these variables, both systems have had varying degrees
of success (U.S. EPA, 1993b).
Passive systems may be used in conjunction with active
systems. An example of this may be the use of a low-
permeability passive system for the closed portion of a
monofill unit (for remedial purposes) and the installation
of an active system in the active portion of the monofill
unit (for future use).
Selection of construction materials for either type of gas
control system should consider the elevated tempera-
ture conditions within a covered surface disposal unit as
compared to the ambient air or soil conditions in which
gas control system components are constructed. Be-
cause ambient conditions are typically cooler, water
containing corrosive waste constituents may be ex-
pected to condense. This condensate should be consid-
ered in selecting construction materials. Provisions for
managing this condensate should be incorporated to
prevent accumulation and possible failure of the collec-
tion system.
Passive Systems
Passive gas control systems rely on natural pressure
and convection mechanisms to vent methane gas to the
atmosphere. Passive systems typically use "high-per-
meability" or "low-permeability" techniques at a site,
either singularly or in combination. High-permeability
systems use conduits such as ditches, trenches, vent
wells, or perforated vent pipes surrounded by coarse soil
to vent landfill gas to the surface and the atmosphere
(see Figure 7-47). Low-permeability systems block lat-
eral migration through barriers such as synthetic mem-'
branes and high-moisture-containing fine-grained soils
(U.S. EPA, 1993b).
Passive systems may be incorporated into a surface
disposal unit or may be used for remedial or corrective
purposes at both closed and active surface disposal
units. They may be installed within a surface disposal
unit along the perimeter, or between the unit and the
disposal facility property boundary. A detailed discussion
of passive systems for remedial or corrective purposes
may be found in U.S. EPA (1985b).
A passive system may be incorporated into the final
cover system of a surface disposal unit closure design
and may consist of perforated gas collection pipes, high-
permeability soils, or high-transmissivity geosynthetics
located just below the low-permeability gas and hydrau-
lic barrier or infiltration layer in the cover system. These
systems may be connected to vent pipes that vent gas
through the cover system or that are connected to
header pipes located along with perimeter of the surface
disposal unit. The methane gas collection system also
may be connected with a leachate collection system to
vent gases in the headspace of leachate collection pipes
(U.S. EPA, 1993b).
Some problems have been associated with passive sys-
tems. For example, snow and dirt may accumulate in
vent pipes, preventing gas from venting. Vent pipes at
the surface are also susceptible to clogging by vandal-
ism.
Active Systems
Active gas control systems use mechanical means to
remove gas from surface disposal units and consist of
either positive pressure (air injection) or negative pres-
sure (extraction) systems. Positive pressure systems
induce a pressure greater than the pressure of the mi-
grating gas and drive the gas out of the soil and/or back
to the surface disposal unit in a controlled manner.
Negative pressure systems extract gas from a surface
disposal unit by using a blower to pull gas out of the unit.
Negative pressure systems are more commonly used
because they are more effective and offer more flexibility
in controlling gas migration. The gas may be recovered
for energy conversion, treated, or combusted in a flare
system. Typical components of a flare system are shown
in Figure 7-48. Negative pressure systems may be used
as either perimeter gas control systems or interior gas
collection/recovery systems. For more information re-
garding negative pressure gas control systems, refer to
U.S. EPA(1985b).
An active gas extraction well is depicted in Figure 7-49.
Gas extraction wells may be installed within the surface
disposal unit or, as depicted in Figure 7-50a and Figure
7-50b, perimeter extraction trenches could be used.
One possible configuration of an interior gas collec-
tion/recovery system is illustrated in Figure 7-51. The
performance of active systems is not as sensitive to
freezing or saturation of cover soils as that of passive
systems. Although active gas systems are more effec-
tive in withdrawing gas from a surface disposal unit,
capital, operation, and maintenance costs of such sys-
tems will be higher as these costs can be expected to
continue throughout the post-closure period. At some
future time, owners and operators may wish to convert
149
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Gas Vent
Top Layer
Low-Permeability Layer
Vent Layer
Waste
Figure 7-47. Passive gas control system (venting to atmosphere) (U.S. EPA, 1993b).
T7E—Waste Gas
Inlet Vahro
(propanej
Concrete Base
Gas From
Landfill
Source: E.C. Jordan Co., 1990.
Figure 7-48. Example schematic diagram of a ground-based landfill gas flare (U.S. EPA, 1993b).
active gas controls into passive systems when gas pro-
duction diminishes. The conversion option and its envi-
ronmental effect (i.e., gas release causing odors, and
health and safety concerns) should be addressed in the
original design.
There are many benefits to recovering gas from surface
disposal units. Monofill gas recovery systems can re-
duce monofill gas odor and migration, can reduce the
danger of explosion and fire, and may be used as a
source of revenue that may help to reduce the cost of
closure. For more information on the benefits to recov-
ering monofill gas, see the references U.S. EPA (1993b)
and SWANA (1992).
7.9 Other Design Features
7.9.1 Access
At a minimum, a permanent road should be provided
from the public road system to the site. For larger sites,
the roadway should be 20 to 24 ft (6 to 7 m) wide for
two-way traffic. For smaller operations a 15 ft (5 m) wide
road can suffice. Additionally, the roadway should be
gravel surfaced at the least, in order to provide access
regardless of weather conditions. Grades should not
exceed equipment limitations. For loaded vehicles, most
uphill grades should be less than 7 percent and downhill
grades less them 10 percent.
150
-------
48* Corr. Steel Pipe
w/ Hinged Lid
Backfill, Compact by
Hand in 6* Layers
Butterfly Valve
Monitoring Port
Header with 3"
Dia. Branch Saddle
Kanaflex PVC Hose
4" Dia Sch 80 PVC
Solid Pipe
Soil Backfill
Bentonite/Soil Seal •
Soil Backfill
4" Dia Sch 80 PVC
Slotted Pipe
Gravel Backfill •
4' Sch 80 PVC Cap
VVM*
2--0-
12',
Slotted Length
Varies
(2/3 Landfill
Depth)
Slotted Length
Varies
(1/2 Well Depth)
Bore
Figure 7-49. Example of a gas extraction well (U.S. EPA, 1993b).
Temporary roads are used to deliver sludge to the work-
ing area from the permanent road system. Temporary
roads may be constructed by compacting the natural soil
present and by controlling drainage, or by topping roads
with a layer of gravel, crushed stone, cinders, crushed
concrete, mortar, bricks, lime, cement, or asphalt bind-
ers to make the roads more serviceable.
Under the Part 505 regulation, access to surface dis-
posal sites must be restricted (see Section 7.2.1.4).
Fencing with gates that lock might be necessary to
restrict access in densely populated areas. Natural bar-
riers such as hedges, trees, embankments, or ditches,
along with warning signs might be adequate in less-
populated areas. In remote areas, it might be sufficient
to post warning signs that say, "Do not enter," "No tres-
passing," or "Access restricted to authorized personnel
only." Such posting also might be sufficient where there
has been a low-rate application of sewage sludge.
7.9.2 Soil Availability
The quantity and adequacy of onsite soil for use as a
bulking agent and for covering sludge will have been
determined during the site selection process. The logis-
tics of soil excavation, stockpiling, and consumption,
151
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Existing Cow
• Refuse
•GeotaxtHe
Washed Gravel
t-— PE Pipe O
Bottom of Trench Excavation
Figure 7-50a. Perimeter extraction trench system (U.S. EPA, 1993b).
Flexible Hose
Quick Connect
Coupling
Ortlice Plate
Butterfty Valve
Ground Surface
Clean So* Backfill
Washed Gravel
net
^-HOPE Pipe
Figure 7-SOb. Perimeter extraction trench system (U.S. EPA, 1993b).
152
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Gas
Tieelmant/Procettlng
FacWy
Figure 7-51. Example of an interior gas collection/recovery system (U.S. EPA, 1993b).
however, are more thoroughly evaluated during design.
Excavation and stockpiling of soil must be closely coor-
dinated with soil use for the following reasons:
• Soil determined to be suitable for use and readily
excavated may be located in selected areas of the
site. The excavation plan should designate that
these areas be excavated before filling has pro-
ceeded atop them.
• Accelerated excavating programs may be desirable
during warm weather to prevent the need to excavate
frozen soil during cold weather.
• Soil stockpiles should be located so that runoff will
not be directed into future adjacent excavations and/
or sludge filling areas and to minimize erosion.
7.9.3 Special Working Areas
Special working areas should be designated on the site
plan for inclement weather or other contingency situ-
ations. Access roads to these areas should be of all-
weather construction and the area kept grubbed and
graded. Arrangements for special working areas may
include locating such areas closer to the surface dis-
posal site entrance gate (Figure 7-52).
7.9.4 Buildings and Structures
At larger surface disposal sites or where climates are
extreme, a building should be provided for office space
and employee facilities. Since most surface disposal
units operate year-round, regardless of weather, some
protection from the elements should be provided for the
employees. Sanitary facilities should be provided for
both operation and hauling personnel. At a large site, a
building might be provided for equipment storage and
maintenance. At smaller sites, buildings cannot be jus-
tified, but trailers might be warranted.
Buildings on sites that will be used for less than 10
years can be temporary, mobile structures. The design
and location of all structures should consider gas move-
ment and differential settlement caused by decompos-
ing sludge.
7.9.5 Utilities
Large surface disposal sites should have electrical,
water, communication, and sanitary services. Remote
sites may have to extend existing services or use ac-
ceptable substitutes. Portable chemical toilets can be
used to avoid the high cost of extending sewer lines;
potable water can be trucked in; and an electric gener-
ator can be used instead of having power lines run onto
the site.
Water should be available for drinking, dust control,
washing mud from haul vehicles before entering the
public road, and employee sanitary facilities. A sewer
line may be desirable, especially at large sites and
at those where leachate is collected and treated with
domestic wastewater. Telephone or radio communi-
cations may be necessary since accidents or spills
153
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! PAVED
ROAD
WET WEATHER
OPERATIONAL
AREA
TRENCH
DRY WEATHER OPERATIONAL
AREA
2—TRENCH
GRAVEL ROAD
3*$
OPERATIONS a
MAINTENANCE
A
i*.«
u
D
^-
PUBLIC ROAD
Figure 7-52. Special working area.
can occur that necessitate the ability to respond to calls
for assistance.
7.9.6 Lighting
If dumping operations occur at night, portable lighting
should be provided at the operating area. Alternatively,
lights may be affixed to haul vehicles and onsite equip-
ment. These lights should be situated to provide illumi-
nation to areas not covered by the regular headlights of
the vehicle.
If the site has structures (e.g., employee facilities, ad-
ministrative offices, equipment repair or storage sheds),
or if there is an access road in continuous use, perma-
nent security lighting might be desirable.
7.9.7 Wash Rack
For surface disposal units where operational procedures
call for frequent contact of equipment with the sludge, a
cleaning program should be implemented. Portable
steam cleaning units or high-pressure washers may be
used. A curbed wash pad and collection basin may be
constructed to collect and contain contaminated wash
water. The contaminated water may be either pumped
to a septic tank/soil absorption system or dispersed with
the sludge. The washing facility should be used to clean
mud from haul vehicles, in order to keep sludge and mud
off the highway.
7.10 References
1. American Society for Testing Materials (ASTM). 1987. Annual
book of ASTM standards, Vol. 4.08. Soil and rock: Building
stones. Philadelphia, PA: ASTM.
2. American Society of Chemical Engineers (ASCE)/Water Pollution
Control Federation (WPCF). 1969, Design and construction of
sanitary and storm servers. In: ASCE manual on engineering
practice No. 37/WPCF manual of practice No. 9.
3. Brown and Calclwell. 1979. Colorado Springs long-range sludge
management study. City of Colorado Springs, CO.
4. Freeze and Cherry. 1979. Groundwater. Englewood Cliffs, NJ:
Prentice-Hall.
5. Keeney, D., K. Lee, and L. Walsh. 1975. Guidelines for the ap-
plication of wastewater sludge to agricultural land in Wisconsin.
Technical Bulletin No. 88. Wisconsin Department of Natural Re-
sources, Madison, Wl.
6. Koerner, R.M. 1986. Designing with geosynthetics. Englewood
Cliffs, NJ: Prentice-Hall.
7. Lambe, T.W., and R.V. Whitman. 1969. Soil mechanics. New
York, NY: John Wiley & Sons, Inc.
8. Loehr, R., W. Jewell, J. Novak, W. Clarkson, and G. Friedman.
1979. Land application of wastes, Vol. 2. New York, NY: Van
Nostrand Reinhold.
9. Lue-Hing, C., D. Zenz, and R. Kuchenrither. 1992. Municipal
sewage sludge management: Processing, utilization, and dis-
posal. In: Water quality management library, Vol. 4. Lancaster,
PA: Technomic Publishing Co.
10. Solid Waste Association of North America (SWANA). 1992. A
compilation of landfill gas field practices and procedures (March).
154
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11. Sowers, G.F. 1979. Soil mechanics and foundations: Geotechni-
cal engineering. New York, NY: MacMillan.
12. Sowers, G.B., and G.F. Sowers. 1970. Introductory soil mechan-
ics and foundations, 3rd ed. New York, NY: MacMillan.
13. Stamm, J.W., and J.J. Walsh. 1988. Pilot-scale evaluation of
sludge landfilling: Four years of operation. EPA/600/2-88/027
(NTIS PB88-208434) (May).
14. U.S. Department of Agriculture. 1986. Urban hydrology for .small
watersheds. Soil Conservation Service. NTIS PB87-101580 (June).
15. U.S. Department of the Navy. 1982. Engineering design manual
NAVFAC DM-7-1. Washington, DC (May).
16. U.S. EPA. 1994. A plain English guide to the EPA,503 biosolids
rule. EPA/832/R-93/003 (June).
17. U.S. EPA. 1993a. Use of alternative materials for daily cover at
municipal solid waste landfills. EPA/600/R-93/172 (NTIS PB93-
227197) (September).
18. U.S. EPA. 1993b. Solid waste disposal facility criteria, technical
manual. EPA/530/R-93/017 (NTIS PB94-100-450). Washington,
DC (November).
19. U.S. EPA. 1990. Guidance for writing case-by-case permit require-
ments for municipal sewage sludge. EPA/505/8-90-001 (May).,
20. U.S. EPA. 1989. Seminar publication: Requirements for hazard-
ous waste landfill design, construction, and closure. EPA/625/4-
89/022. Cincinnati, OH.
21. U.S. EPA. 1988a. Guide to technical resources for the design of
land disposal facilities. EPA/625/6-88/018. Cincinnati, OH.
22. U.S. EPA. 1988b. Technical resource document: Design, con-
struction, and evaluation of clay liners for waste management
facilities. EPA/530/SW-86/007F. Cincinnati, OH (September).
23. U.S. EPA. 1988c. Lining of waste containment and other im-
poundment facilities. Draft technical resource document. EPA/
600/2-88/052 (September).
24. U.S. EPA. 1987a. Technical guidance document: Prediction/ mitigation
of subsidence damage to hazardous waste landfill covers. Inter-
agency Agreement No. DW21930680-01-0. Cincinnati, OH (July).
25.,U.S. EPA. 1987b. Implications of current soil liner permeability
research results. In: Proceedings of the 13th Annual Research
Symposium, Land Disposal Remedial Action, Incineration, arid
Treatment of Hazardous Waste (July). EPA/600/9-87/015, pp. 9-25.
26. U.S. EPA. 1987c. Geosynthetic design guidance for hazardous
waste landfill cells and surface impoundments. EPA/600/2-87/097
(NTIS PB88-131263) (December).
27. U.S. EPA. 1986a. Highlights in U.S. technological development
in landfiliing of sludge. EPA/600/D-86/056 (NTIS PB86-174067).
Cincinnati, OH.
28. U.S. EPA. 1986b. Draft technical resource document: Design,
' construction, and evaluation of clay liners for waste management
facilities. EPA/530/SW-86/007. Cincinnati, OH (March).
29. U.S. EPA. 1986c. Technical manual: Geotechnical analysis for
review of dike stability (GARDS). EPA Contract No. 68-03-3183,
Task 19. Cincinnati, OH (March).
30. U.S. EPA. 1986d. Technical guidance document: Construction
quality assurance for hazardous waste land disposal facilities.
EPA Contract No, 68-02-3952, Task 32. Cincinnati, OH (October).
31 .U.S. EPA. 1985a. Covers for uncontrolled hazardous waste sites.
EPA/540/2-85/002. Cincinnati, OH (September).
32. U.S. EPA. 1985b. Handbook: Remedial action at waste disposal
sites (revised). EPA/625/6-85/006! Cincinnati, OH (October).
33. U.S. EPA. 1984a. Hydrologic evaluation of landfill performance
(HELP) model, Vol. 1. User's guide for Version 1. EPA/530/SW-
84/009 (NTIS PB85-100840).
34. U.S. EPA. 1984b. Hydrologic evaluation of landfill performance
(HELP) model, Vol. 2. Documentation for Version 1. EPA/530/
SW-84/010 (NTIS PB85-100832).
35. U.S. EPA. 1984c. Technical-economic study of sewage sludge
disposal on dedicated land. EPA/600/2-84/167 (NTIS PB85-
117216). Cincinnati, OH.
36. U.S. EPA. 1983a. Technical resource document: Lining of waste
impoundment and disposal facility. Report No. SW-870. Cincin-
nati, OH (March). (Revised version of Reference 19).
37. U.S. EPA. 1981. Process design manual for land treatment of
municipal wastewater. EPA/625/1-89/013. Cincinnati, OH.
38. U.S. EPA. 1979. Process design manual for sludge treatment and
disposal. EPA/625/1-79/011. Washington, D.C.
39. U.S. EPA. 1978a. Sludge treatment and disposal, Vol. 2.
EPA/625/4-78/012. Cincinnati, OH.
40. U.S. EPA. 1978b. Land cultivation of industrial wastes and mu-
nicipal wastes: State-of-the-art study, Vol. 1. EPA/600/2-78/140a
(NTIS PB-287 080).
41. U.S. EPA. 1977. Cost of land spreading and hauling sludge from
municipal wastewater treatment plants: Case studies.
EPA/530/SW/619 (NTIS PB-274-875). Washington, DC.
42. U.S. EPA/OSW. 1987a. Draft minimum technology guidance on
single liner systems for landfills, surface impoundments, and
waste piles: Design, construction, and operation. EPA/530/SW-
85/013. Washington, DC (May).
43. U.S. EPA/OSW. 1987b. Draft minimum technology guidance on
double liner systems for landfills, surface impoundments, and
waste piles: Design, construction, and operation. EPA/530/SWr
87/014. Washington, DC (May).
44. U.S. Soil Conservation Service. 1972. Drainage of agricultural
land: A practical handbook for the planning, design, construction,
and maintenance of agricultural drainage systems. U.S. Depart-
ment of Agriculture.
45. Van Schilfgaarde, ed. 1974. Drainage for agriculture. Madison,
Wl: American Society of Agronomy.
46. Wahls, H.E. 1981. Tolerable settlement of buildings. J. Geotech.
Eng. 107(GT11):1,489-1,504.
47. Winterkom, H.F., and H.Y. Fang. 1975. Foundation engineering
handbook. New York, NY: Van Nostrand Reinhold.
155
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Chapter 8
Surface Disposal of Domestic Septage
Domestic septage is defined in the Part 503 regulation
as the liquid or solid material removed from a septic
tank, cesspool, portable toilet, Type III marine sanitation
device, or a similar system" that receives only domestic
sewage (household, non-commercial, non-industrial
sewage) (see Section 3.2.2). Table 3-2 in Chapter 3 lists
some characteristic of septage.
The most common, and usually most economical,
method of domestic septage disposal is land application
(e.g., land spreading, irrigation, overland flow) which is
not addressed in this manual. Disposal at an existing
wastewater treatment plant is a viable and economical
option if the plant is reasonably close to the source and
has adequate processes and capacity to handle the
domestic septage.
Surface disposal practices for domestic septage include
placement in monofills (trenches), lagoons, and munici-
pal solid waste landfills.
8.1 Regulatory Requirements for
Surface Disposal of Domestic
Septage
The regulatory requirements for the surface disposal of
domestic septage are not as extensive as those for
sewage sludge. Neither the pollutant limits nor the
pathogen requirements of Part 503 apply if domestic
septage is placed on an active sewage sludge unit. The
regulation does, however, specify requirements for vec-
tor attraction reduction for domestic septage that is sur-
face disposed.
Two alternatives are available for placing domestic sep-
tage on an active sewage sludge unit (see Options 9-12,
Table 3-9 in Chapter 3). One alternative is to achieve
vector attraction reduction by raising the pH of the do-
mestic septage to 12 with alkali addition for 30 minutes,
and maintaining the pH at 12 or greater for 30 minutes
without adding more alkali. If pH reduction is used to
achieve vector attraction reduction, each container of
domestic septage must be monitored for compliance. The
person who placed the domestic septage on the active
sewage sludge unit must then certify that vector attrac-
tion reduction was achieved (see Figure 8-1) and de-
velop a .description of how it was achieved. The certifi-
cation and the description must be kept for 5 years.
If vector attraction reduction is not achieved by alkali
addition (as described above), the owner or operator of
the surface disposal site must achieve vector attraction
reduction by injecting or incorporating the domestic sep-
tage into the soil, or by covering it with soil daily. Certi-
fication that all these requirements have been met and
a description of how they were met must be developed
and maintained for 5 years. (Figure 8-1 shows the re-
quired certification statement.)
If domestic septage is placed in a monofill (such as a
trench), surface impoundment, dedicated disposal site
or other sludge-only surface disposal site, its disposal is
covered by the requirements in the Part 503 regulation
for such disposal sites (except for requirements for pol-
lutant limits and pathogen reduction). These requirements
are discussed further in Chapters 3, 4, 5, 7, 9, and 10.
If domestic septage is placed in a municipal solid waste
landfill, its disposal is covered by the requirements of
40 CFFt Part 258 for the disposal of non-hazardous
waste. These requirements are discussed in Section
3.4.3. Note that because of the requirement that waste
pass the Paint Filter Liquids Test (see Section 3.4.3),
domestic septage must be dewatered so that it contains
no free liquid before it can be placed in a municipal solid
waste landfill.
Compliance with federal regulations governing domestic
septage does not ensure compliance with state require-
ments. State programs may not define domestic septage
the same way as the federal regulations. In addition,
state requirements may be more restrictive or may be
administered in a different manner from the federal regu-
lation. It is important to check with the state septage
coordinator to find out about state requirements.
8.2 Domestic Septage Disposal Lagoons
The use of lagoons for septage disposal is a common
alternative in rural areas. As discussed in Section 7.5.3,
if the lagoon is not part of the treatment process then
these lagoons are considered surface disposal sites
under the Part 503 rule.
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An individual placing domestic septage on a surface disposal site must maintain
the following certification statement for 5 years:
"I certify, under penalty of law, that the vector attraction reduction
requirements in §503.33(b)(12) have/have not been met. This determination
has been made under my direction and supervision in accordance with the
system designed to ensure that qualified personnel properly gather and
evaluate the information used to determine that the vector attraction
requirements have been met I am aware that there are significant penalties
for false certification, including the possibility of fine and imprisonment."
The owner or operator of the surface disposal site must maintain the following
certification statement for 5 years:
"I certify, under penalty of law, that the management practices in §503.24
and the vector attraction reduction requirements in [insert §303.33(b)(9)
through §503.33(b){l 1) when one of those requirements is met] havertiave
not been met. This determination has been made under my direction and
supervision in accordance with the system designed to ensure that qualified
personnel properly gather and evaluate the information used to determine
that the management practices [and the vector attraction requirements, if
appropriate] have been met I am aware that there are significant penalties
for false certification, including the possibility of fine and imprisonment."
Signature
Date
Flgur* 8-1. Certifications required when domestic septage Is placed In a surface disposal site (U.S. EPA, 1994).
Domestic septage disposal lagoons are usually a maxi-
mum of 1.8 m (6 ft) deep and allow no effluent or soil
infiltration. These lagoons require placement of domes-
tic septage in small incremental lifts (15 to 30 cm, or 6
to 12 in.) and sequential loading of multiple lagoons for
optimum drying. Most are operated in the unheated
anaerobic or facultative stage. Odor problems may be
reduced by placing the lagoon inlet pipe below liquid
level and having water available for haulers to immedi-
ately wash any spills into the lagoon inlet line (U.S. EPA,
1994). Section 7.5.3 presents detailed information about
lagoon design.
8.3 Monofills (Trenches) for Domestic
Septage Disposal
Domestic septage is placed sequentially in multiple
trenches in small lifts, 15 to 20 cm (6 to 8 in.), to
minimize drying time. When the trench is filled with
domestic septage, 0.6 m (2 ft) of soil should be
placed as a final covering, and new trenches opened.
An alternate management technique allows a filled
trench to remain uncovered to permit as many solids to
settle, as well as liquids to evaporate and leach out, as
possible. Then the solids, as well as some bottom and
sidewall material, are removed and the trench is reused
(U.S. EPA, 1984).
Additional information on monofills is presented in Sec-
tion 7.5.2.
8.4 Codisposal at Municipal Solid Waste
Landfill Unit
Design information for codisposal at a municipal solid
waste landfill is presented in Section 7.6; codisposal
operation is discussed in Section 9.3.3.
"i
8.5 References
1. U.S. EPA. 1994. A plain English guide to the EPA 503 biosolids
rule. EPA/832/R-93/003.
2. U.S. EPA. 1984. Handbook: Septage treatment and disposal.
EPA/625/6-84/009. Cincinnati, OH (October).
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Chapter 9
Operation
9.1 Purpose and Scope
The purpose of this chapter is to introduce an approach
for implementing a sewage sludge disposal operation.
The operation of a sewage sludge surface disposal
site can be viewed as an ongoing construction project.
As with any construction project, it must proceed
according to detailed plans. Unlike conventional con-
struction, however, the operating parameters of a sew-
age sludge surface disposal site often change and may
require innovative alterations and contingency plans. An
effective operation requires a detailed operational plan
and a choice of equipment compatible with the sludge
characteristics, the site conditions, and the selected
active sewage sludge unit.
9.2 Regulations
9.2.1 Part 503
9.2.1.1 Management Practices That Affect the
Operation of Surface Disposal Sites
The Part 503 rule includes management practices that
affect the daily operation of surface disposal sites.
These management practices must be followed when
sewage sludge is placed on a surface disposal site
because they help protect human health and the envi-
ronment from the reasonably anticipated adverse ef-
fects of pollutants in sewage sludge (U.S. EPA, 1994).
The following management practices are addressed in
Chapter 7:
• Collection of Runoff (Section 7.2.1.1 and Section 7.8.2).
• Collection of Leachate (Section 7.2.1.2 and Section
7.5.7).
• Limitations on Methane Gas Concentrations (Section
7.2.1.3 and Section 7.8.3).
• Restrictions of Public Access (Section 7.2.1.4 and
Section 7.9.1).
• Protection of Ground Water (Section 7.2.1.5).
The following management practices required under
Part 503 also impact the operation of a surface disposal
site (U.S. EPA, 1994):
• Restrictions on Crop Production. Food, feed, or fiber
crops may not be grown on an active sewage sludge
unit unless approved by the permitting authority. The
owner or operator of the surface disposal site must
demonstrate to the permitting authority through man-
agement practices that public health and the environ-
ment are protected if crops are grown. If the
owner/operator wishes to grow crops on the site, he
or she must obtain permission from the regulatory,
agency. If permission is granted the owner/operator
will be required to implement certain management
practices to ensure that unsafe levels of pollutants
are not taken up by crops that are eaten by people.
These special management practices might include
testing crops for the presence of pollutants and test-
ing animal tissue for the presence of pollutants if
animal feed is produced on the site, or setting a
monitoring schedule for the crops and any animal
feed products derived from the site.
• Restrictions on Grazing. Animals must not be allowed
to graze on an active sewage sludge unit unless
approved by the permitting authority. The owner/op-
erator of a surface disposal site must demonstrate to
the permitting authority that public health and the
environment are protected if animals are allowed to
graze. If the owner/operator wishes to graze animals
on the site, he or she must obtain a permit. The
permit would require specified management prac-
tices, such as monitoring the concentration of pollut-
ants in any animal product (dairy or meat). This
restriction on grazing helps ensure that unsafe levels
of pollutants do not find their way into animals from
which people obtain food.
A site on which the production of crops and/or grazing
is allowed is considered a dedicated beneficial use site.
(Operational considerations at beneficial TINE sites are
discussed in Section 9.3.4.3 of this chapter.)
9.2.1.2 Operational Standards for Pathogen and
Vector Attraction Reduction
Pathogens are disease-causing organisms, such as
certain bacteria and viruses, that might be present in
sewage sludge. Vectors are animals, such as rats,'or
159
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insects, such as flies, that might be attracted to sewage
sludge and can spread disease after coming into contact
with sewage sludge. The Part 503 rule includes require-
ments concerning the control of pathogens and the re-
duction of vector attraction for sewage sludge placed
on an active sewage sludge unit site. Sewage sludge
can be placed in an active sewage sludge unit only if
the pathogen and vector attraction reduction require-
ments are met (see Section 3.4.2.2, Section 3.4.2.3,
and Table 3-9).
To meet pathogen and vector attraction reduction re-
quirements under Part 503 the following daily operation
should take place (U.S. EPA, 1994):
• For pathogen reduction, either the sewage sludge
placed on an active sewage sludge unit must meet
Class A or Class B pathogen requirements, or a cover
(soil or other material) must be placed on the active
sewage sludge unit at the end of each day. If a daily
cover is placed on the active sewage sludge unit, no
other pathogen reduction requirements apply (see
Section 3.4.2.2).
• For vector attraction reduction, one of several options
listed in Table 3-4 must be met. These include placing
a daily cover on the active sewage sludge unit, or,
injecting or incorporating the sewage sludge into the
soil (see Section 3.4.2.3).
In most cases, owners or operators of surface disposal
sites will place a daily cover on the active sewage sludge
unit to meet pathogen and vector attraction reduction
requirements (U.S. EPA, 1994).
Regarding vector attraction reduction, if the method
used to place sewage sludge at a TINE site is subsur-
face injection or incorporation (see Section 7.7.4), then
the site can meet the Part 503 requirement for vector
attraction reduction (Options 9 or 10) if the sewage
sludge is injected or incorporated within a specified time
frame after the sewage sludge has undergone a patho-
gen reduction process, as described in Section 3.4.2.2
and Section 3.4.2.3. If a method other than subsurface
injection or incorporation is used, then the other options
of achieving vector attraction reduction described in
Section 3.4.2.3 must be used (see Section 9,3.4.3).
9.2.1.3 Other Requirements Under Part 503
Affecting Operation
The following requirements under part 503 also impact
daily operations at sewage sludge surface disposal sites
but have been addressed elsewhere in this document:
• Frequency of monitoring requirements (see Section 10.2)
• Reporting requirements (see Section 11.2)
• Recordkeeping requirements (see Section 11.2)
9.3 Method-Specific Operational
Procedures
For the purposes of this chapter, the site operation
may be viewed in two parts: the first part (Section 9.3)
concerns operational procedures that are specific to
the chosen active sewage sludge unit; the second part
(Section 9.4) concerns general operational proce-
dures that are independent of the active sewage
sludge unit.
9.3.1 Operational Procedures for
Monofilling
Operations dependent on the type of monofill include:
• Site preparation
• Sludge unloading
• Sludge handling and covering
Because these operations vary for each monofill, they
will be discussed as functions of the monofills intro-
duced in Chapter 2.
9.3.1.1 Trench
For trenches, subsurface excavation is required so
that sludge can be placed entirely below the original
ground surface. In trench applications, the sludge is
usually dumped directly into the trench from haul ve-
hicles. Soil is not used as a sludge bulking agent. Soil
is used as cover, usually in a single, final application.
Two kinds of trenches have been identified including
(1) narrow trench and (2) wide trench. Narrow trenches
have widths less than 10 ft (3.0 m). Wide trenches
have widths greater than 10 ft (3.0 m). Section 2.3.1
and Section 7.5.2.1 should be consulted for specific
design criteria.
Site Preparation
Site preparation includes all tasks required prior to the
receipt of sludge. Tasks include clearing and grub-
bing, grading the site, constructing access roads, and
excavating trenches.
The location of access roads depends on the topog-
raphy and the land utilization rate. Narrow trenches
use land rapidly and require more extensive road
construction. Wider and/or longer trenches may require
vehicle access roads along both sides of the trench.
Prior to grading, the area should be cleared and
grubbed. Grading should be done on the site (1) to
control runoff and (2) to provide grades compatible
with equipment to be used. For example, drag lines
and trenching machines operate more efficiently on
level surfaces. Narrow trenches may require less
grading due to their applicability to hilly terrain.
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Progressive trench construction is the most efficient
procedure for a narrow trench operation. The initial
trench is constructed using appropriate equipment and
the soil either (1) piled along the length of the trench, or
(2) stockpiled in a designated area, or (3) graded to
ground level. Soil is often piled on the uphill,side of the
trench and used to prevent runoff from entering the
trench. Succeeding trenches are constructed parallel to
the initial trench. The trench dimensions and the dis-
tance between the trenches should follow design speci-
fications.
Trenches may require dikes positioned intermittently
across the width of the trench, especially if such
trenches are long. The dikes should be of sufficient
height to contain the sludge and attendant liquids and
allow proper trench filling and covering. Equipment may
be used inside wide trenches to construct dikes.
On-going site preparation is critical for proper execution
of a trenching operation. Depending on the quantity of
sludge received, a designated trench'volume should
always be maintained in advance of filling operations.
Ideally, trenches should be prepared at least one wdek
ahead of the current landfilling operation.
Sludge Unloading
.Signs should be placed to designate which trench is the
active sewage sludge unit. Sludge is usually unloaded
from haul vehicles via direct dumping. Metal extension
chutes or pumping, however, may also be employed. If
direct dumping is employed, an appropriately sized area
should be prepared at the lip of the trench so that
transport vehicles can safely back up to the trench edge
for unloading. Sludge unloading can occur along the
length of both sides of the trench if necessary. The entire
unloading area should be kept clear of discharged
sludge and periodically regraded to facilitate safe un-
loading operations.
Sludge Handling and Covering
Sludge should be uniformly distributed throughout the
trench. Otherwise, depressions that could cause
ponding are likely to occur as the fill settles. Narrow and
wide trenches should be filled only to a level where a
sludge overflow will not occur due to displacement dur-
ing cover application. Markers on trench sidewalls can
be used for this purpose. The appropriate level for
sludge filling can best be established via experimenta-
tion using test loads.
Concurrent excavation, filling, and covering of trenches
is a sequential operation that requires a coordination of
effort. When the sludge has filled the trench to the
designated level, cover material should be applied using
either soil freshly excavated from a parallel trench or soil
stockpiled during excavation of the trench being filled.
Depending upon the solids content of the sludge and the
width of the trench, coyer application should proceed as
follows:
If the sludge has a solids content from 15 to 20 percent,
the width of the trench should be 2 or 3 ft (0.6 to 0.9 m).
Cover application should be via equipment based on
solid ground adjacent to the trench. Covering equipment
may include a backhoe with loader, excavator, or trench-
ing machine.
If the sludge has a solids content from 20 to 28 percent,
the width of the trench is technically unlimited. It is
limited, however, by the requirement that cover be ap-
plied by equipment based on solid ground. Covering
equipment may include a backhoe with loader, excava-
tor, track loader, or dragline.
If the sludge has a solids content of 28 percent or above,
the width of the trench is unlimited. Cover application
can be via equipment which proceeds out over the
trench pushing cover over the sludge. Covering equip-
ment usually is a track dozer. In all cases, initial layers
of cover should be carefully applied to minimize sludge
displacement. (See Chapter 12 for information on final
cover requirements for sewage sludge monofills.)
Operational Schematics
The preceding information has been included to gener-
ally describe the operation of trenches. Figures 9-1
through 9-4 illustrate specific trench operations,
9.3.1.2 Area Fill
For area fills, sludge is usually placed above the original
ground surface. In area fill applications, soil is usually
mixed with the sludge as a bulking agent. Cover may be
used in both intermediate and final applications.
Three kinds of area fills have been defined including (1)
area fill mound, (2) area fill layer, and (3) diked contain-
ment. In area fill mound operations, sludge/soil mixtures
are usually stacked into piles approximately 6 ft (1.8 m)
high. In area fill layer operations, sludge/soil mixtures
are spread evenly in layers 0.5 to 3 ft (0.15 to 0.9 m)
thick. In diked containment operations, sludge (with or
without bulking soil) is dumped into pits contained by
dikes constructed above the ground surface. Section
2.3.2 and Section 7.5.2.2 should be consulted for spe-
cific design criteria.
Area Fill Mounds
Area fill mounds may be employed in a variety of topog-
raphies. Usually such operations are conducted on level
ground. Mound monofills, however, are also well suited
to construction against a hillside that can provide con-
tainment on one or more sides.
Site Preparation. The first step is to prepare the sub-
grade. Depending on design specifications this may
161
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Figure 9-1. Narrow trench operation.
sv s-S' SsZ
& *>' *V-
j'T-Z^^f+WBg^tKfJfl _^^f J\f^^^//\ f^lr ff •
- •-'y^^*ulLClA^j^->'^ .Xx^/f \ > x-^ ^
>-^/(M4>:' >"
-•x*'
Figure 9-2. Wide trench operation at solid waste landfill.
Figure 9-3. Wide trench operation with dragline.
162
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Figure 9-4. Wide trench operation with interior dikes.
include underdrains and/or liners for leachate collection.
Due to the large amount of soil required for proper
operation of area fill mounds, emphasis should be
placed on securing sufficient soil material. Accordingly,
the fill should be confined to a small area and proceed
vertically to the maximum extent possible. This will re-
duce the areal extent of the monofill and consequently
reduce erosion and silt-laden runoff from denuded ar-
eas, provided the slope does not become excessive.
The excavation can be carried out in phases to take
advantage of soil differences. Any soil that has to be
stockpiled for use as a sludge bulking agent should be,
placed in compacted, sloping piles. To keep the soil dry,
piles may be covered with tarpaulins. Wet soils, because
they are not suitable for sludge bulking, should not be
stockpiled. Soil that is stockpiled should be placed as
close as possible to points of eventual use and access
to stockpiles provided.
Sludge Unloading. The sludge may be unloaded either
in the filling area or in the designated unloading and
mixing area near the bulking agent stockpile. The un-
loading area should be clean and relatively level for safe
passage of trucks. Haul vehicles should not drive over
completed sludge filling areas.
Sludge Handling and Covering. Operational procedures
should be provided to specify what soils are to be mixed
with sludge, where they are to be obtained, and how
they are to be mixed and/or placed over the sludge. The
amount of material required for each function is deter-
mined by site design specifications that take into ac-
count soil and sludge characteristics. Preliminary trial
and error tests to determine sludge/soil ratios that pro-
duce sludge with appropriate consistencies should be
attempted during initial operations.
Construction of area fill mounds requires that the
sludge/soil mixture be relatively stable. Sludge/soil
mounds are generally applied in a series of lifts with
each lift containing one level of mounds. When com-
pleted, the lift should be covered with a layer of soil
sufficient to safely support on-site operating equipment.
(See Chapter 12 for information on final cover require-
ments for sewage sludge monofills.),
Area Fill Layer
Area fill layers may also be employed in a variety of topog-
raphies. Layer operations consist of a series of sludge
layers with intermediate and final cover applications.
Site Preparation. As with area fill mounds, the first step
is to prepare the subgrade. Again, liners and/or subdrain
systems may be utilized depending on hydrogeological
conditions. Fill areas for layer operations should be
nearly level. Although the soil requirements of such
operations are less than those of area fill mounds, it may
be necessary to import soil. In any case, soil stockpiles
should be established, both for use as bulking agents
and cover soils. Areas should be excavated only as they
are used, to the maximum extent possible. This will
reduce the amount of denuded area subject to erosion.
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Sludge Unloading. Specific unloading and sludge/soil
mixing areas may be maintained or sludge can be
placed directly in the fill area. An effective method in
layer operations is to maintain soil stockpiles on the fill
area itself. Bulldozers then mix and layer the sludge in
one operation. Again, storage areas should be located
away from traffic.
Sludge Handling and Covering. In general, design
specifications based on sludge characteristics will give
some indication of the required amounts of bulking
agent. Nevertheless, it is always advisable to conduct
preliminary trial and error tests to determine bulking"
ratios appropriate for supporting equipment. The depth
of intermediate and final cover can also be determined
in this manner. (See Chapter 12 for information on final
cover requirements for sewage sludge monofills.)
Diked Containment
Diked containments are essentially aboveground wide
trenches and, as such, use similar procedures and
equipment. The design and construction of dikes is more
complex. Diked containments are generally used at
sites with high ground-water tables or bedrock, and/or
where a sewage sludge with a low solids content is
being disposed.
Site Preparation. The first step in preparing the site for
diked containment is to provide a suitable subgrade or
a liner, if necessary. (See Chapter 7 for information on
foundations, liner and leachate collection systems, and,
slope stability analyses.) The dike base is then con-
structed maintaining design dimensions and slopes
(generally from 2H:1V to 3H:1V for sideslopes). Suc-
ceeding layers are then applied and each layer com-
pacted by passing equipment over it. Alternatively, the
containment area may be constructed against one or
more steep sideslopes. A ramp should be provided for
unloading vehicles. *
Sludge Unloading. Sludge may be unloaded from the
top of the dike or in an area designated for sludge/soil
mixing. Slopes and grades of access roads should be
maintained to design specifications. Provisions should be
made for inclement weather (e.g., stockpiled soil kept dry).
Sludge Handling and Covering. The containment area
is filled with sludge in layers, usually with intermediate
soil or gravel cover provided at predetermined heights.
Draglines are frequently used to apply intermediate and
final cover. (See Chapter 12 for information on final
cover requirements for sewage sludge monofills.)
Operational Schematics
The preceding information has been included to gener-
ally describe the operation of area fills. Figures 9-5
through 9-8 illustrate specific area fill operations.
9.3.2 Operational Procedures for Lagoons
Facultative sludge lagoons and sludge drying lagoons
are used for surface disposal of sewage sludge.1 Sec-
tion 2.5 and Section 7.5.3 should be consulted for spe-
cific design criteria for these active sewage sludge units.
9.3.2.1 Facultative Sludge Lagoons
Operational considerations for facultative sludge la-
goons include the loading or placement of sludge into
the FSLs and routine operation.
Start-up and Loading
FSLs should be initially filled with effluent. Ideally, that
effluent should then have about three to six weeks for
development of an aerobic surface layer prior to the
introduction of digested sludge. All FSLs should be
loaded daily, with the loading distributed equally be-
tween FSLs. Loadings should be held below 20 pounds
VS per 1,000 square feet per day (1.01 VS/ha-d) on an
average annual basis. As indicated earlier, considerable
flexibility does exist. Loads can vary from day to day,
and batch or intermittent loading of once every four days
or less is acceptable. Shock loadings, such as with
digester cleanings, should be distributed to all operating
FSLs in proportion to the quantity of sludge they pos-
sess. FSLs should be loaded during periods of favorable
atmospheric conditions, particularly just above ground
surface, to maximize odor dispersion. The fixed and
volatile sludge solids loadings to the FSLs and their
volatile contents should be monitored quarterly.
Daily Routine
Surface mixers should operate for a period of between
6 and 12 hours. Operation should not coincide with FSL
loading and should always be during the hours of mini-
mum human exposure (usually midnight to 5 a.m.) and
during periods of favorable atmospheric conditions. FSL
supernatant return to the wastewater treatment process
should be regulated to minimize shock loadings of high
ammonia. Supernatant return flows should be monitored
so that their potential impact on the liquid treatment
process can be discerned. The sludge blanket in a
lagoon should not be allowed to rise higher than 2 feet
below the operating water surface.
9.3.2.2 Operations for Sludge Drying Lagoons
Operating procedures for drying lagoons used for final
disposal include:
• Pumping liquid sludge, over a period of several
months or more, into the lagoon. The pumped sludge
As discussed in Sections 2.5 and 7.5.3, the surface disposal provi-
sions of the Part 503 rule do not apply when sludge is treated in a
lagoon. Section 1.1 provides more information on differentiation be-
tween sludge disposal, storage and treatment.
164
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Figure 9-5. Area fill mound operation.
Figure 9-6. Area fill layer operation.
Figure 9-7. Area fill operation inside.trench.
165
-------
SOIL STOCKPILE
SOU. STOCKPILE
Figure 9-8. Diked containment operation.
is normally stabilized prior to application. The sludge
is usually applied until a lagoon depth of 24 to 48
inches (0.7 to 1.4 m) is achieved.
• Decanting supernatant, either continuously or inter-
mittently, from the lagoon surface and returning it to
the wastewater treatment plant.
• Filling the lagoon to a desired sludge depth and then
permitting it to dewater. Depending on the climate
and the depth of applied sludge, a solids content of
between 20 to 40 percent will be obtained in 3 to 12
months.
9.3.3 Operational Procedures for Codisposal
In codisposal operations, sludge is disposed of at an
MSW landfill. Two kinds of codisposal operations have
been identified including (1) sludge/solid waste mixture
and (2) sludge/soil mixture. For sludge/solid waste mix-
tures, sludge is mixed directly with solid waste and
landfilled at the working face. For sludge/soil mixtures,
sludge is mixed with soil and used as cover over com-
pleted refuse fill areas. Section 2.7 and Section 7.6
should be consulted for specific design criteria.
9.3.3.1 Sludge/Solid Waste Mixture
At the landfill, once sludge receipt has begun, every
effort should be made to take full advantage of the
absorptive capacity of the solid waste. Consequently,
the sludge should be mixed with the solid waste as
thoroughly as possible. One procedure employed calls
for solid waste to be dumped at the bottom of the
working face, and subsequently pushed, spread, and
compacted by equipment working up the working face.
Under these circumstances, sludge can be handled in
two alternative ways. The first way includes:
1. Dump the solid waste at the bottom of the working face.
2. Dump the sludge atop the solid waste pile.
3. Thoroughly mix the sludge and solid waste.
4. Push, spread, and compact the sludge/solid waste
mixture up the working face.
The second method can be accomplished in the fol-
lowing way:
1. Dump the solid waste at the bottom of the working face.
2. Push, spread, and compact the solid waste up the
working face.
3. Dump the sludge at the top of the working face.
4. Push the sludge down the working face, spreading
it evenly across the solid waste.
If small quantities of sludge are received at MSW land-
fills (i.e., less than 5 percent) it may be desirable to
confine sludge dumping to a selected location on the
working face. This approach is useful in MSW land-
fills that are sufficiently large to ensure that solid
waste dumping proceeds simultaneously along a wide
working face.
Precautions should be taken to contain any sludge that
escapes from the working face. Containment can be
achieved either by (1) landfilling the sludge in a small
depression or (2) constructing a refuse or soil berm at
the bottom of the working face.
Another factor to be considered at MSW landfills receiv-
ing sewage sludge is the increased potential for odor
166
-------
problems to occur. Appropriate steps can be taken to
control odors including more frequent application of
cover and spot addition of lime.
9.3.3.2 Sludge/Soil Mixture
Another option for handling sludge at MSW landfills is
mixing the sludge with soil and then applying the mixture
as cover material oversolid waste filled areas. Although
this technically is not sludge landfilling, it is a viable
alternative, is particularly useful in promoting vegetative
growth in completed fill areas, and is performed at nu-
merous MSW landfills.
If a sludge/soil mixture is determined to be a suitable
material for the erosion layer of the final cover, the
mixture can be applied as follows:
1. Spread sludge as received uniformly over the ground
surface in a 3 to 6 in. (8 to 15 cm) thickness in an
area designated for this purpose.
2. Disc the sludge into the soil. The resulting mixture of
sludge to soil should be about 1:1.
3. If necessary, spread lime or a masking agent over
the sludge/soil mixture for odor control.
4. After a period ranging from 1 to 8 weeks (depending
on rainfall and climate) scrape up the sludge/soil
mixture and spread it over the clay infiltration layer
9.3.3.3 Operational Schematics
The preceding information has been included to gener-
ally describe the operation of MSW landfills. Figures 9-9
through 9-11 illustrate specific codisposal operations.
9.3.4 Operational Procedures at Dedicated
Surface Disposal Sites
Important operational considerations at DSD sites in-
clude aesthetics (i.e., community concerns), labor,
and issues related specifically to beneficial DSD sites.
Each of these operational considerations for DSD sites
are discussed below. Design considerations affecting
operations at DSD sites, such as determining the most
appropriate sludge placement method to use and cal-
culating the acceptable sludge disposal rate, are ad-
dressed in Section 7.7.
9.3.4.1 Aesthetics at DSD Sites
The major community concern at most DSD sites is
odor. If the DSD site is located on a treatment plant site
that is remote from public areas, odor may not present
a problem. But DSD sites may need to be located in
populated areas if that is where land is available, espe-
cially in urban areas.
Generally, odor problems from sludge are the result of
anaerobic (septic) conditions. When disposing large
quantities of liquid sludge at DSD sites, the soil should
be maintained in an aerated condition via surface drain-
age that precludes ponding of water on the site's surface
and includes subsurface drainage and/or tillage (if nec-
essary). Subsurface injection by sludge spreading vehi-
cles provides another means of reducing odors.
Liquid sludge storage lagoons at DSD sites are a po-
tential source of odor. Use of a lagoon, if properly
designed, will reduce the potential for odors. If the
sludge, is well stabilized, odor problems are usually
infrequent but may occur (e.g., during a spring thaw
after extended cold weather or during a major distur-
bance of the sludge lagoon as would occur during
bottom sediment cleanout). Typical attempts at control-
ling odors from sludge lagoons involve:
• Locating the .sludge lagoon as far from public access
areas as possible.
• Providing as large a buffer area around the site as
possible.
• Adding lime to the lagoon.
• If the POTW sludge treatment process is having
problems (e.g., a sour digester), if possible the re-
sulting poorly stabilized sludge should not be added
to the DSD site storage lagoon.
Dust and noise levels from use of heavy equipment
(e.g., tractors, subsurface injector vehicles) at DSD
sites may be a concern in some communities. In an
agricultural area, dust and noise should be no worse
than expected from normal farming operations and
should create no problems. In an urban area, use of
buffer zones and vegetative screening (trees arid
shrubs around the site) may be necessary to mitigate
public impact.
9.3.4.2 Labor
Labor needs for DSD sites can vary widely, 'from one
hour of operator time weekly for smaller sites using
spray methods to 11 persons needed for one-half year
each (where climate limits sludge spreading to certain
seasons) at sites with larger operations using the sub-
surface injection method, based on reports from individ-
ual DSD sites. The 11-person operation included one
person for each dredger, one person for each injector,
and one person for each tiller tractor. Two people were
hired as relief personnel for the injector and tractor
operators, and one person served as supervisor of the
crew (U.S EPA, 1984). Additional personnel will be
heeded at dedicated beneficial use sites where crops
are grown (e.g., for seeding and harvesting).
167
-------
/^SEHS
foad/uK
j^fes^Sp*
Figure 9-9. Sludge/solid waste mixture operation.
Figure 9-10. Sludge/solid waste mixture with dikes.
Figure 9-11. Sludge/soil mixture.
168
-------
9.3.4.3 Operational Considerations at Dedicated
Beneficial Use Sites
A POTW or other DSD site owner might choose to
establish a beneficial DSD site if soil erosion or soil
acidity are a problem at the site or if the facility is
committed to a beneficial use policy. The sewage sludge
increases the soil's productivity and can reduce soil
erosion and acidity. The high disposal rates of sewage
sludge placed on these sites can help supply nutrients
that act as fertilizers, as well as organic matter that
conditions the soil. Crops grown on beneficial DSD
sites have been sold as animal feed or for use in the
production of methanol or other alternative fuels (Lue-
Hing, 1992).
Part 503 requires that an owner/operator of a beneficial
DSD site must be able to demonstrate to the permitting
authority that, by implementing certain management
practices, public health and the environment will be
protected if crops are grown or animals are grazed. The
permitting authority may specify site-specific manage-
ment practices to ensure that unsafe levels of pollutants
are not taken up by crops that might be eaten by people
(including animals that are allowed to graze on the site).
Such management practices may include testing of
crops or animal tissue (e.g., dairy or meat) for the pres-
ence of pollutants and specification of a monitoring
schedule for the testing.
The crops chosen to be grown at a beneficial DSD site
need to be compatible with the site's sludge disposal
rate and the sludge disposal method used at the site
(see Sections 7.7.4 and 7.7.5). Crops with high nutrient
needs (e.g., nitrogen) will be able to tolerate higher
sludge disposal rates and also can help reduce the
amounts of nutrients that may be released as pollutants
into surface runoff and leachate.
9.4 General Operational Procedures
9.4.1 Management Practices Required Under
Part 503
Surface disposal site owners/operators must meet the
Part 503 management practice for surface disposal re-
lated to operation of the surface disposal site. These
address the operation of leachate collection systems,
collection of surface water runoff, crop production and/
or grazing of animals, access restrictions, and include
monitoring requirements and pathogen and vector con-
trol requirements.
9.4.1.1 Leachate Collection System
If the surface disposal site owner chooses to have a liner
and leachate collection system onsite (in lieu of meeting
the Part 503 pollutant limits for surface disposal), then
Part 503 requires that site owners operate the leachate
collection system according to design specifications and
must perform routine and other needed maintenance for
the system. Chapter 7 includes a more detailed discus-
sion of leachate collection at sewage sludge surface
disposal sites.
9.4.1.2 Collection of Surface Water Runoff
A surface disposal site owner/operator must implement
the management practices required for all surface dis-
posal sites. One of the management practices requires
that surface water runoff be collected from an active
sewage sludge unit and that the runoff collection system
must be capable of handling runoff from a 24-hour,
25-year storm event. Chapter 7 includes a more detailed
discussion of collection of runoff at sewage sludge sur-
face disposal sites.
9.4.1.3 Crop Production and/or Grazing of
Animals
Part 503 management practices state that no crop pro-
duction or grazing can be conducted at any surface
disposal site, including beneficial DSD sites, unless the
owner/operator can demonstrate to the permitting
authority that, through management practices, public
health and the environment will be protected from any
reasonably anticipated adverse effects of pollutants—in-
cluding pathogens—in sewage sludge when crops are
grown or animals are grazed.
9.4.1.4 Access Restrictions
Under Part 503, public access to a surface disposal site
must be restricted while an active sewage sludge unit is
on the site and then for 3 years after the last active
sewage sludge unit has been closed. Access restrictions
are discussed in Section 7.9.1.
9.4.1.5 Monitoring Requirements
If a surface disposal site does not have a liner and
leachate collection system, then the Part 503 pollutant
limits for surface disposal must be met (see Chapter 3)
and must also monitor ground water for nitrate. The
owner/operator must then monitor the sewage sludge
as required by Part 503 for the regulated pollutants.
Surface disposal site owners must also monitor to en-
sure that certain pathogen and vector attraction reduc-
tion requirements are being met. In addition, air must be
monitored for methane gas if sewage sludge placed on
an active sewage sludge unit is covered either daily or
at closure. Monitoring requirements are discussed in
Chapter 10.
169
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9.4.1.6 Pathogen and Vector Attraction
Reduction
Sewage sludge at surface disposal sites must meet the
Part 503 operational standards for pathogen and vector
attraction reduction, as discussed in Chapters. Regard-
ing pathogens, Part 503 requires that the pathogen
density be reduced through certain processes and also
contains management practices that help ensure that
pathogens will not regrow.
5.4.2 General Operational Procedures for
Sewage Sludge Surface Disposal Sites
Operational factors that are generally applicable to all
sewage sludge disposal sites include:
• Environmental control practices
• Inclement weather practices
• Hours of operation
9.4.2.1 Environmental Control Practices
In many cases, environmental controls must be used at
sewage sludge surface disposal sites. These environ-
mental controls are described in the following sections
and outlined in Table 9-1.
• Spillage. Enroute and on-site spillage of sludge must
be cleaned up as soon as possible. Haul vehicles
Table 9-1. Environmental Control Practices
enroute to the disposal site should report even small
spills to the operation supervisor, so emergency
clean-up crews can take prompt action. On-site spills
should be controlled as much as possible. It is a
good policy to have lime on hand at all sludge dis-
posal operations for spot application to spills if prompt
clean-up is not feasible. The use of haul vehicles
with baffles on them has been used effectively to
limit spills.
• Siltation and erosion. The presence of silt-laden run-
off from the site is often the result of improper grading.
Grades of 2 to 5 percent should be maintained where
feasible to promote overland surface drainage, while
minimizing flow velocities. Denuded areas should be
kept to a minimum during site operation. Ongoing
construction and maintenance of sediment control
devices (e.g., grass waterways, diversion ditches, rip-
rap, sediment basins) are critical for an environmen-
tally sound operation. During site completion, proper
final grading, dressing, and seeding prevent long-
term erosion; and siltation problems.
• Mud. Mud is usually caused by improper drainage
but can be a problem at any site during heavy rains
or spring thaws. To minimize the effect of mud on op-
erations, access roads should be constructed of gravel.
If practical, a wash pad should be located near the
exit gate to clean mud from transport vehicles.
Environmental
Problems
Spillage
Siltation and Erosion
Hud
Dust
Odors
Noise
Aesthetics
Health
Safety
E
5-
Ol
£
O-
ro
oo
X
Maintain Washrooms
for Personnel
X
O>
"*- c
o c
o
Ol V)
c: i.
•i-
ro a
c
01 co
t- h-
oo -*:
o
Ol 3
=3 f—
X
X
01
i- a
10 CC
c: c
+-> 1—
il
X
X
Maintain Fencing
X
X
•a
c=
to
en
Maintain Buffer Area
Grass
X
X
X
X
X
X
c
Proper Equipment Ma
tenance
X
X
X
3
o-
r
5
01
la
3 +J
>>rto
Q. I/
00 -=C
X
X
o
•u
cd'-
O- U
£i t_
4J
oo
o
1
X
X
x.
X
.c
Workers Supplied wil
Aerators
X
X
X
X
a
aj
Ol
3
OO
t-
a>
o
X
X
X
X
•o
s~
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ST-
aj E
•(-> 0
2 U-
X
X
170
-------
• Dust. Dust is usually caused by wind or the move-
ments of haul vehicles and equipment. To minimize
dust, access roads should be graveled. Also, areas
that are covered with intermediate or final soil cover
should be vegetated as soon after their completion
as possible. As an alternative, water can be applied
to dusty roads.
• Odors. Odors can be a serious problem at a sewage
sludge surface disposal site unless preventive steps
are taken. The sludge should be covered as fre-
quently as necessary to minimize odor problems.
Lime or chemical masking agents can be applied to
reduce odor problems. An effective means of reduc-
ing odors is to limit storage of the sludge. Ideally,
storage of sludge should be abcomplished at the
wastewater treatment plant.
• Noise. Noise sources at surface disposal sites in-
clude operating equipment and haul vehicles. Gen-
erally, the noise is similar to that generated by any
heavy construction activity, and is confined to the site
and the streets used to bring sludge to the site. To
minimize the effect, every effort should be made to
route traffic through the least populated areas. Fur-
ther, the site can be isolated so that the noise cannot
carry to nearby neighborhoods. The use of earthen
berms and trees as noise barriers can be very effec-
tive. On the site, noise protection for employees will
be governed by existing Occupational Safety and
Health Act (OSHA) standards.
• Aesthetics. To make the surface disposal site publicly
acceptable, every attempt should be made to keep -
the site compatible with its surroundings. During site
preparation, it is important to leave as many trees
as possible to form a visual barrier. Earthen berms
can be similarly used. The use of architectural effects
at the receiving area, the planting of trees along the
property line, and confining dumping to designated
areas will assist in the development of a sound op-
eration. Additionally, every attempt should be made
to minimize the size of the working area.
• Worker health. Although there is a possibility that
pathogens will be present in sludge, particularly if
- undigested, no health problems have been reported
by site operators. Nevertheless, personnel should
use caution when transporting, handling, and covering
sludge. Washing facilities should be located on or
near the disposal site.
• Worker safety. As with any construction activity,
safety methods must be implemented in accordance
with OSHA guidelines. Work areas and access roads
must be well marked to avoid on-site vehicle mishaps.
9.4.2.2 Inclement Weather Practices
Prolonged periods of rainy weather or freezing tempera-
tures can impede routine operation of a sludge surface
disposal site. Anticipating the operational problems and
addressing contingency operations in the operation plan
will promote efficient operations. A listing of potential
inclement weather problems and solutions has been
included in Table 9-2.
9.4.2.3 Hours of Operation
Hours of operation should coincide with hours of sludge
receipt. In this way, personnel and equipment are avail-
able to direct trucks to the proper unloading location;
assist if trucks become mired in sludge or mud; or cover.,
the sludge quickly to minimize odors. If the operation
plan calls for daily covering of sludge, hours of opera-
tion should continue at least 1/2 hr past the hours of
sludge receipt to allow for cleanup activities. Sludge
deliveries after hours at the surface disposal site should
be discouraged.
9.5 Equipment
A wide variety of equipment is utilized at surface dis-
posal sites. Equipment selected depends largely on (1)
the disposal method and design dimensions employed
and (2) quantity of sludge received.
Because equipment represents a large capital invest-
ment and accounts for a large portion of the operating
cost, equipment selection should be based on a careful
evaluation of the functions to be performed and the .cost
and ability of various machines to meet these needs.
Contingency equipment for downtime and maintenance
may be necessary at larger sites. These may be rented
or borrowed from other municipal functions.
Table 9-3 provides guidance on the suitability of equip-
ment to perform selected sludge disposal tasks. Table 9-4
provides typical equipment selections for seven opera-
tional schemes. These matrices are meant to give general
guidance on the selection of sludge disposal equipment.
It should be noted, however, that general recommenda-
tions on equipment selection can be misleading. In all
cases, final selection should be based on site-specific
considerations. Figures 9-12 through 9-15 illustrate typi-
cal equipment used at surface disposal facilities.
The importance of employing qualified and well-trained
personnel at sludge surface disposal sites cannot be
overstated. Qualified personnel often make the differ-
ence between a well-organized, efficient operation and
a poor operation. Information on staffing and personnel
for surface disposal sites is included in Chapter 11.
171
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Table 9-2. Inclement Weather Problems and Solutions
Inclement
Weather
Conditions
Het
Cold
Sludge Loading
and Transport
Problem: If hauling
great distances, wet
weather conditions
may increase liquid
content of sludge.
Solution: Cover
transport vehicle.
Problem: Sludge
freezes in haul
vehicles.
Solution; Line
trucks with salt
water, straw, sand
or oil. Do not
allow prolonged
exposure to cold
(park in garage).
Use exhaust to
heat the trailer.
Site Preparation
Problem: Maneuvera-
bility of equipment
hindered in mud.
Solution: Plan to move
operation to an acces-
sible working area.
Problem: Depressions
accumulate water, may
draw flies, mosquitos.
Solution: Grade area
to promote surface
runoff. Use insecti-
cides only when neces-
sary.
Problem: Deep pene-
tration of frost in
trench areas.
Solution:
- Construct trenches
during good weather
and save for cold
months.
- Do not remove snow
(acts as insulator)
or allow vehicles
to ride on trench-
ing areas (causes
frost to penetrate
deeped into the
ground).
- Hydraulic rippers
or jackhammers are
to be used as a last
resort.
Sludge Unloading
Problem: Maneuvera-
bility of transport
vehicles hindered in
mud.
Solution: Place sand
or grave! in areas to
improve traction. In-
crease deoth of road
mater-al.
Problem: Instability
of tre.ncn walls .may
cause collapse while
unloading.
Solution: Have trans-
port ve.nicle dump at
trench 1ip and push
sludge into ,trench
with equipment.
Proble-n: Mud and sludge
accumulates on haul
vehicles and equipment.
Solution: A washing pad
at the Deceiving area
will clean vehicles.
Sludge Handling
and Covering
Problem: When
mixing sludge
with refuse or
soil , need more
mixing material.
Solution: Ensure
sUT'TcTent supply
o* refuse or soil
material .
Problem: Ponded
water collecting
in trenches.
Solution: Use
potable pump
to remove
excess water.
Prooleei:
freeze."
Tailgates
Solution: (1) Spray
ethylene slycol on
frozen parts. (2) use
exhaust to heat frozen
parts.
Problem: Previously
(fall season) muddy
roads fonr. severe ruts
and chuck holes.
Solution: Regrade and
build before winter
freeze.
problem: Deep
penetration of
frost in cover
supply areas.
Solution: Accum-
ulate stockpile
in good weather.
Ensjre supply of
cover material;
insulate piles
with tarpaulin or
hay.
Problem; Equip-
ment freeze-up.
Solution: Trucks
or crawlers should
be well cleaned
of sludge and
soil.
172
-------
Table 9-3. Equipment Performance Characteristics
Equipment Name
Trenching Machine
Backhoe with Loader
Track Loader
Wheel Loader
Track Dozer3
Scraper
Dragl i ne
Gr.ader
Tractor with Disc
TRENCH
Narrow
Trench
o
* o
2
Vt
8 en
1 fc
01 >
£- Q
G G
G
G F
- G
- G
- G
G
Wide
Trench
C "
o
U
i-
in
g
CJ CT
1 fc
>
t- O
1— 0
-
G F
F -
G G
G -
G
AREA FILL
Mound
en T-
"3 re en en
1C . en o> f- -r-
£- X 3 3 >
O »r- r— O O
l/> £ 10 Z
F G F G G
G F G F F
- G - F G
G - F - -
Layer
o>
c
*3 :c cn cn
a: en o> •«-•!—
c en s- i-
,- -r- -a > >
O *r- i — (O O
10 Z 10 — 1 0
G G G - -
- G - G G
G - F G G
- - - G G
Diked
Contain-
ment
•
o
'^3
u
? s
I— W)
3 c en
3: O
G G
- F
ludge/
Soil
en
^
ro
i>
a.
0) 0> C •»-
en c T- f.
1 'X 3 S
r— -i- rd O
CA> E 3: O
F - G F
- - F F
G F - G
- - F F
F - - -
- G - -
G - Good. Fully capable of performing function listed. Equipment could be selected solely on basis of
F = Fair. Marginally capable of performing function listed. Equipment should be selected on basis of
full capabilities in other function.
- = Not applicable. Cannot be used for function .listed
a Caterpillar D-6 generally is the largest track dozer appropriate for a sludge landfi.n.
Table 9-4. Typical Equipment Selection Schemes
Equipment
Trenching Machine
Backhoe with Loader
Excavator
Track Loader
Wheel Loader
Track Dozer
Scraper
Dragline
Grader
Tractor with Disc
.Total
1
Trench Method
Narrow Trench
,a 2° 3c 4d 5e
1 2
11 \* 1
1
1« 1 1 2«
12235
Wide Trench
12345
1 1* 1 1*
1» 1 1 2*
1* 1
12224
Area Fill Method
Mound
12345
1* 1* 1* 1
11111
1 1
1* 1 1
1* 1* 1
12455
layer
12345
1*
1 1 1 2* 2
1* 1* 1* 1
12234
Diked
Containment
12345
1 1* 1* 1 2*
1* 1 1
Till
12334
Co-disposal Hethodf
Sludge/Refuse
12345
I
1* 1 1
- - 1 12
Sludge/ Soil
12345
1* 1* 2*
1 1 1* 2* 2
] 1 2 4 5
a Scheme 1 - 10 wet tons/day
b Scheme 2-50 wet tons/day
c Scheme 3-100 wet tons/day
d Scheme 4 - 250 wet tons/day
e Scheme 5-500 wet tons/day
f Additional equipment only
* Hay not receive 100S utilization
173
-------
Figure 9-12. Scraper.
iSrCS^V^-*'"' ^S*V!lM!K*>-—-'j^d
rl^v^K.^sl^^i^
Figure 9-13. Backhoe with loader.
174
-------
Figure 9-14. Load lugger.
Figure 9-15.. Trenching machine.
175
-------
and air (outputs). The main concern with monitoring
sewage sludge is ensuring that the nature and fre-
quency of sampling adequately characterizes the con-
centration of pollutants in sludge. The main concern with
environmental monitoring is ensuring that the number
and location of sampling points are adequate to charac-
terize background levels (for ground water) and that
sampling is frequent enough to determine whether a
particular requirement is met.
10.3.1 Parameters of Interest
As noted in Section 10.2.1, the main parameters of
interest for monitoring at sewage sludge disposal sites
include: (1) .arsenic, chromium, and nickel, which have
been identified as the main metals of concern in sludge;
(2) pathogens and vector attraction reduction; (3) ni-
trates in the ground water; and (4) methane gas, which
can reach explosive concentrations when sewage sludge
is covered and anaerobic conditions develop in the sub-
surface. Where a treatment works is known to receive
significant inputs of other types of pollutants from indus-
trial sources, then the number of inorganic and organic
species that must be monitored might be larger.
U.S. EPA (1992a) covers requirements for the monitor-
ing, sampling, and analysis of pathogens and vector
attraction reduction efforts under Part 503 in detail and
should be consulted for further guidance. The remainder
of this chapter focuses on other types of monitoring.
Chapter 2 of U.S. EPA (1993a) also provides guidance
on monitoring of sewage sludge for surface disposal.
At sites where leachate or runoff is collected and re-
leased to surface waters as a point source, NPDES
permits may require monitoring of a number of parame-
ters, such as chemical or biological oxygen demand
(COD/BOD), turbidity, pH and selected chemical spe-
cies. At sludge surface disposal sites arsenic, chro-
mium, nickel, pathogens, and nitrates would be likely
additional parameters for leachate and surface water
monitoring, because they are monitored in other parts
of the system.
10.3.2 Media To Be Sampled
Monitoring at sludge surface disposal sites may require
sampling of alf types of media: (1) solids or semisolids
for sludge characterization, (2) liquids in the form of
leachate, surface water, and ground water; and (3) air
to detect presence of methane. Sewage has to be moni-
tored if an active sewage sludge unit does not have a
liner and leachate collection system, ground water has
to be monitored unless a certification is made, and air
has to be monitored if the unit is covered. Other special
considerations for monitoring of specific media are
addressed in Sections 10.4.2 (Ground Water), 10.4.3
(Leachate and Surface Water), and 10,4.4 (Methane).
10.3.3 Sampling Locations
Sampling locations will depend on the type of media being
sampled. Sewage sludge can either be sampled during
loading or on the ground after dumping or spreading.1
Table 10-1 identifies recommended sampling points for
various types of sewage sludge. In general, sampling
locations should be as close to the stage before final
disposal as possible. Domestic septage can be sampled
from the container used to haul the domestic septage or
after placement (the risk of penalties for being out of
compliance after placement apply here as well). Section
10.4,1 addresses sampling of sludge in more detail.
Ground-water monitoring wells (Section 10.4.3) should be
located up- and down-gradient from the surface disposal
site based on flow net analysis and other hydrogeologic
information obtained during site investigations (Sections
6.4.3 and 6.5.2). Section 10.4.2 discusses monitoring well
network design further. Leachate collection systems and
ponds for collection of surface water runoff should be
sampled at the point of discharge to surface waters. Meth-
ane gas monitoring devices, if required, should be placed
in each structure within the surface disposal site bounda-
Sampling after spreading poses the risk of penalties if samples
exceed pollutant limits and should only be done if pollutants do not
vary greatly in concentration and are known to fall well below pollutant
limits.
Table 10-1. Chemical and Physical Parameters Typically Determined for Monitoring of Sewage Sludge Application Sites
Sample Chemical and Physical Parameters
Ground Water Field Measured Parameters for Sampling: pH, electrical conductivity, temperature, turbidity; Other Common
Parameters: Total hardness, total dissolved solids, chlorides, sulfates, total organic carbon, nitrate nitrogen, total
phosphorus, surfactants, selected metals (arsenic, chromium, nickel and others, if appropriate) or trace organics
where applicable, pathogens/indicator organisms.
Fecal conforms, total phosphorus, total nitrogen (Kjeidahl), dissolved oxygen, chemical/biological oxygen demand
(COD/BOD), temperature, pH, suspended solids.
Exchangeable ammonium nitrogen and nitrate-nitrite nitrogen, available phosphorus, pH, electrical conductivity,
organic carbon, exchangeable cations (calcium, magnesium, potassium, sodium), total and extractable metals—DTPA
or 0.1 N HCI (arsenic, cadmium, chromium, copper, nickel, zinc), cation exchange capacity, particle size distribution
(texture), other known or suspected contaminants.
Source: Adapted from Granato and Pietz (1992).
Surface Water
Soil
178
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ries, and at site boundaries based on prevailing wind
direction (Section 10.4.4).
10.3.4 Sampling Frequency
The Part 503 regulation establishes frequency of sampling
to characterize sludge at surface disposal sites based on
the amount of sludge placed on a site, in a year (Table
10-2). If climatic conditions do not allow placement of the
sludge year-round, the number of sampling events should
be spaced over the period of active placement. For exam-
ple, if placement of sludge only occurs 6 months of the
year, and the minimum frequency is 6 times per year, then
sampling would need to occur once a month during the
period of active spreading. If no previous sampling data
are available on the sludge to be disposed, it may be
desirable to sample more frequently until enough data are
collected to determine the minimum number of samples
required to satisfy a 90 percent confidence limit for sample
representativeness (Section 10.4.1).
Ground-water sampling is usually done on a quarterly
basis, although specif ic state regulatory programs might
specify different intervals. When leachate or surface
runoff is discharged to surface water, the sampling inter-
val will be specified in the NPDES permit, which again
is typically four times a year. Air monitoring for methane
gas, when required, should be continuous.
10.3,5 Sample Collection and Handling
Procedures
Sample collection and handling procedures should be
clearly defined and consistently followed to minimize
sample errors attributable to the sampling process. This
can be accomplished with a written sampling protocol
that includes:
• Specification of personnel responsible for collecting
samples, and training requirements to ensure that
sampling protocols are correctly followed.
Table 10-2. Frequency of Monitoring for Surface Disposal of Sewage Sludge
Parameter
Metals
Applies to
All Class A Pathogen
Reduction
Alternatives (PRA):
Fecal Coliform &
Salmonella sp.
Validity of Analytical Data over Time and When Sampling/Analysis Must Occur
METALS
Data remain valid for biosolids if ho significant change in volatile solids.
Determine monitoring' frequency in [accordance with monitoring frequency
requirements.
PATHOGENS CLASS A
Because regrowth can occur, monitoring should be done:
(a) sufficiently close to the tune of biosolids use so data are available and no additional
regrowth occurs before land application, or
(b) when biosolids are prepared for sale or give-away in a bag or other container for
land application, or
(c) when biosolids are prepared to meet EQ requirements.
Additional Information on Each Class A Pathogen Category
Class A PRA 1: Data remain valid as long as biosolids remain dry before use.
Thermal Treatment, Tj temperature, and moisture content should be monitored continuously to ensure
Moisture, Particle Size effectivene7s of treatment
& Time Dependent
Class A PRA 2:
High pH, High
Temperature
Class A PRA 3:
Enteric Virus & Viable
Helminth Ova to
Establish Process
Class A PRA 4:
Enteric Virus & Viable
Helminth Ova for
Unknow Process
Class A PRA 5:
PFRP
Class A PRA 6:
PFRP Equivalent
Monitor to ensure that pH 12 (at 25°C) is maintained for more than 72 hours.
Once destroyed, enteric virus or viable helminth ova does not regrow. To establish a
process, determine with each monitoring episode until the process is shown to
consistendy achieve this status. Then continuously monitor process to ensure its
validity.
Once destroyed, enteric virus or viable helminth ova does not regrow. Monitor
representative sample of biosolids material:
(a) to be used or disposed, or
(b) when prepared for sale or give-away in a bag or other container for land
application, or , .
(c) when prepared to meet EQ requirements.
Monitor continuously to show compliance with time and temperature or irradiation
requirements.
Monitor continuously to show compliance with PFRP or equivalent process
requirements.
179
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Tabl» 10-2. Monitoring Considerations for Key Parameters (continued)
Class BPRA1:
Fecal Coliform
aassBPRA2:
aassBPRA3:
Vector Attraction
Reduction (VAR) 1:
38% Volatile SoUds
Reduction (VSR)
VAR 2
for Anaerobic
Digestion:
If Cannot Meet VAR 1
Lab Test
VAR 3
for Aerobic Digestion:
If Cannot Meet VAR 1
Lab Test
VAR 4:
SOUR Test For
Aerobic Processes
VAR 5:
Aerobic xttJ°C
VAR 6:
Adding Alkaline
Material
VAR 7:
Moisture Reduction
No Unstabilized
Primary Solids
VAR 8:
Moisture Reduction
Primary Unstabilized
Solids
VAR 9:
Injection into Soil
VAR 10:
Incorporation into Soil
VAR 11:
Covered with Soil
Surface Disposal
VAR 12:
Domestic Septage
pH Adjustment
PATHOGENS CLASS B
Measure the geometric mean of 7 samples when used or disposed sufficiently close to
the time of use so that (i) data are available and (ii) no additional regrowth occurs
before land application.
Continuously monitor to show that biosolids are meeting the PSRP requirements.
Continuously monitor to show that biosolids are meeting the equivalent PSRP
requirements.
VECTOR ATTRACTION REDUCTION
Once achieved, no further attractiveness to vectors. If a batch process, determine VSR
for each batch. If for a continuous process, determine: VSR based on material being put
in and withdrawn. Monitor continuously to verify that biosolids axe meeting the
necessary operating conditions.
Once achieved, no further attractiveness to vectors. JK.a batch process, determine VSR
for each batch. If unable to show VSR, then conduct lab test Monitor continuously to
verify that biosolids are meeting the necessary operating conditions.
Monitor continuously to show that biosolids are achieving the necessary temperatures
over time.
Determine pH over time for each batch. Data are valid as long as the pH does not drop
such that putrefaction begins prior to land application.
To be achieved only by the removal of water. Data air valid as long as the moisture
level remains below 30%.
To be achieved only by the removal of water. Data are valid as long as the moisture
level remains below 10%.
No significant amount of biosolids remains on soil surface within 1 hour after injection.
Biosolids must be incorporated into soil within 6 hours after being placed on the soil
surface.
Surface disposed biosolids must be covered daily.
Preparer must ensure that pH is 12 for more than 30 minutes for each batch of domestic
septage treated with alkaline material
Specification of safety precautions, such as use of
gloves when handling or sampling untreated or
treated sewage sludge and cleaning of sampling
equipment, containers, protective clothing, and hands
before delivering samples to others.
Identification of the type of sampling device. For de-
watered sludge, soil sampling devices, such as
scoops, trier samplers, augers, or probes can be used.
Stainless steel materials are best; chrome-plated sam-
plers should be avoided. For leachate and surface water,
sample containers can be filled directly at the points of
discharge or dippers used to transfer liquid to the con-
tainer. For ground water, a wide variety of sampling de-
vices are available. Because nitrate is the only monitoring
parameter specified in the Part 503 regulation, bailers will
probably be the simplest and least expensive sampling
device for ground-water sampling.
180
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• Description of sample mixing and subsampling pro-
cedures when grab samples of sludge are compo-
sited and only part of the composite sample is used
for analysis. This usually requires use of a mixing
bowl or bucket (stainless steel or Teflon) or a dispos-
able plastic sheet in or on which samples can be
mixed and from which a smaller sample can be taken.
• Specification of the size and material of sample con-
tainers. Table 10-3 identifies suitable containers and
minimum volume requirements for sludge sampling.
Sample containers can often be obtained from the
person or laboratory responsible for doing the sample
analysis.
• Specification of sample preservation procedures and
sample holding times. Table 10-3 identifies these re-
quirements for sludge samples. Unless analysis is
done in the field or in an onsite laboratory, sludge
samples are usually cooled to 4°C (i.e., packed in ice).
Holding times vary with the constituent being ana-
lyzed. For example, the maximum holding time for
nitrate is 24 hours unless the sample is acidified, in
which case the holding time is a maximum of 28 days
(U.S. EPA. 1991c). The appropriate regulatory agency,
in coordination with the testing laboratory, should be
contacted to identify any specific sample preservation
procedures and holding times for all specific constitu-
ents being monitored.
• Specification of sample equipment cleaning proce-
dures to ensure that cross-contamination of samples
does not occur. ASTM D5088 (Standard Practice for
Decontamination of Field Equipment Used at Nonra-
dioactive Waste Sites) provides guidance on these
procedures.
• Specification of types and frequency of quality assur-
ance/quality control (QA/QC) samples. Again, the ap-
propriate regulatory agency should be contacted to
determine which types of QA/QC samples may be
required for the site.
• Description of sample chain-of-custody procedures to
ensure that the integrity of samples is maintained
during transport and analysis of samples.
Table 10-3. Sampling Points for Sewage Sludge
Biosolids Type
Anaerobically Digested
Aerobically Digested
Thickened
Heat Treated
Dewatered, Dried,
Composted, or
Thermally Reduced
> Dewatered by Belt
Filter Press,
Centrifuge, Vacuum
Filter Press
Dewatered by
Biosolids Press
(plate and
frame)
Dewatered by
Drying Beds
Compost Piles
Sampling Point
Collect sample from taps on the discharge side of positive displacement pumps.
Collect sample from taps on discharge lines from pumps. If batch digestion is used,
collect sample directly from the digester. Cautions:
1. If biosolids are aerated during sampling, air entrains in the sample. Volatile organic
compounds may be purged with escaping air.
2. When aeration is shut off, solids separate rapidly in welt-digested biosolids.
Collect sample from taps on the discharge side of positive displacement pumps.
Collect sample from taps on the discharge side of positive displacement pumps after
decanting. Be careful when sampling heat-treated biosolids because of:
1. High tendency for solids separation.
2. High temperature of sample (temperature <60"C as sampled) can cause problems
with certain sample containers due to cooling and subsequent contraction
of entrained gases. , ^
Collect sample from material collection conveyors and bulk containers. Collect
sample from many locations within the biosolids mass and at various depths.
Collect sample from biosolids discharge chute.
Collect sample from the storage bin; select four points within the storage bin, collect
equal amount of sample from each point and combine.
Divide bed into quarters, grab equal amounts of sample from the center of each
quarter and combine to form a composite sample of the total bed. Each composite
sample should include the entire depth of the biosolids material (down to the sand).
Collect sample directly from front-end loader while biosolids are being transported or
stockpiled within a few days of use.
Note: The term biosolids will be replaced with "sewage sludge* in the final document.
181
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Each type of media that is sampled should have a separate
written sampling protocol, unless sampling procedures
are the same for different media. U.S. EPA (1994a)
provides detailed guidance on sampling procedure for
sewage sludge. Most of the references cited in Table 6-7
in Chapter 6, address sample collection and handling
procedures in more detail. Keith (1992) provides a use-
ful general guide to development of environmental sam-
pling protocols. Major sources that address soil
sampling in greater detail include: U.S. EPA (1989b),
U.S. EPA (1991b), Boulding (1994), and U.S. EPA
(1992c). Ground-water sampling generally requires the
most complex procedures because of the need to
purge a well before sample collection (Section 10.4.2).
Major sources that address ground-water sampling
procedures include: U.S. EPA (1985), U.S. EPA (1991 c),
andU.S.EPA(1993b).
10.3.6 Sample Analysis Methods
Numerous procedures are available for chemical analy-
sis of environmental samples. For example, there are
five major series of U.S. EPA methods: (1) EPA CLP
(contract laboratory program) for inorganic and organic
analysis; (2) EPA 200 series for water and wastes; (3)
EPA 500 series for organic compounds in drinking water;
(4) EPA 600 series (identified in 40 CFR, Part 146), and
(5) SW-846 methods for solid waste (U.S. EPA, 1986).
The American Society for Testing and Materials (ASTM)
publishes annually standard test methods for analysis
of water (Volumes 11.01 and 11.02) and wastes (Vol-
ume 11.04). The American Pubic Health Association/
Water Environment Federation's compilation of methods
for analyzing water and wastewater is in its 18th edition .
(APHA, 1992). Furthermore, the U.S. Geological
Survey, as well as other federal agencies, also have
developed standard methods for chemical analysis
(mainly in its Techniques of Water Resource Investiga-
tions series). Also, state environmental agencies might
specify their own methods for analysis of certain con-
stituents. For example, New Jersey requires testing of
sulfide reactivity of sewage sludge (personal communi-
cation, Cris Gaines, U.S. EPA Office of Water, April 1994).
Analytical methods in the context of environmental
regulatory programs can be grouped into the following
categories:
• EPA-approved methods have been published in the
Federal Register as the benchmark method for a
specified regulatory purpose (i.e. reporting for NPDES
or drinking water programs). Typically, EPA-approved
methods required sophisticated fixed laboratory
facilities.
• EPA-accepted methods have been evaluated by EPA
against an EPA-approved method and been found to
be equivalent to the EPA-approved method. Manu-
facturer claims that a method is EPA-accepted should
be documented with a letter from EPA stating that the
method has been evaluated by EPA and found to be
equivalent. EPA-accepted methods are not published
in the Federal Register because additions and
changes to this category are so frequent that it is
simpler to let manufacturers provide the necessary
documentation to users.
• Other standard methods involve clearly defined pro-
cedures and protocols defined by state regulatory
programs, other federal agencies (such as the U.S.
Geological Survey) or professional organizations
(such as the American Society for Testing and Mate-
rials and the American Public Health Association). For
specific purposes, EPA may specify or recommend
particular methods from these sources (See Table 10-5).
• Field screening methods involve relatively simple
qualitative (substance is present or absent in relation
to a threshold level), semiquantitative (concentrations
lie within a certain range), or quantitative methods
that can be used in the field or a small laboratory.
Chemical field screening methods tend to be less
expensive than EPA-approved and EPA-accepted
methods, but also less accurate. Potential uses for
these methods are discussed later in this Section.
EPA-Specified Methods
Table 10-4 identifies analytical methods for pathogens,
inorganic pollutants, and other sludge parameters that
are required by the Part 503 regulation. Specific meth-
ods for sample preparation and analysis for the metals
of interest for sewage sludge surface disposal are con-
tained in U.S. EPA (1986) as follows: arsenic (EPA
Methods 3050/3051 and 7060/7061); chromium (EPA
Methods 3050/3051 and 6010/7191/7190); and nickel
(EPA Methods 3050/3051 and 6010/7520). Although
both methods for 7060 and 7061 can be used to analyze
for arsenic, Method 7060 is often preferable because
high concentrations of chromium, cobalt, copper, molyb-
denum, nickel, or silver can cause analytical interfer-
ence in method 7061 (U.S. EPA, 1994b).
Other Standard Methods
Any state regulatory agency that has jurisdiction over a
surface disposal site should be consulted to determine
whether any additional analysis methods are required.
If conditions at a particular site require analysis for
constituents for which there are not EPA or state-speci-
fied methods, the appropriate ASTM or APHA/WEF
method may be selected (see above).
Field Screening Methods
Key considerations in sample analysis include ensuring
that the methods used for regulatory reporting are
acceptable to the permitting authority and minimizing
analytical costs. U.S. EPA-approved methods require
182
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Table 10-4. Minimum Frequency of Monitoring for Surface Disposal of Sewage Sludge
Amount of Biosolids"
(metric tons per 365-day period)
Greater than zero but less than 290
Equal to or greater than 290 but less
than 1,500
Equal to or greater than 1,500 but less
than 15,000
Equal to or greater than 15,000
Methane gas in air
Amount of Biosolids
(English units)
Ave. per day
>0to<0.85
0.85 to <4.5
4.5to<45
^45
per 365 days
>0to<320
320to4 ppmd >4 ppm
10:500
—
5-90
2-50
3-90
—
—
None
None
None
Photometer
RQ Flex Meter
Digestion (As, Cr);
spectrophotometer
Digestion, spectrophotometer
OTHER METHODS
Ion-Selective Electrodes6
ATI/Orion —
Hach Co. —
Solonet —
TM Analytic —
'— • —
— —
— —
— ' • —
0.1
0.1
0.1
0.1
Meter and reference electrode
Meter and reference electrode
Meter and reference electrode
Meter and reference electrode
Note: Manufacturer should be contacted for current status and documentation for EPA approval or acceptance.
* See Appendix C for addresses and phone numbers of manufacturers.
Quant tests measure chromate, HACH wateriest measures Cr(VI) and Hach sludge tests are for total chromium.
0 EPA-accepted methods for NPDES reporting (water samples).
EPA-approved method only if preceded by EPA-apprpved nitric acid digestion.
9 EPA acceptance pending for NPDWR reporting.
183
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extensive laboratory facilities, with relatively high capital
and operating costs, which means that analytical costs
tend to be high. Advances in the portability and accuracy
of instrumentation and techniques for analyzing environ-
mental samples are making chemical analysis in the
field or in small onsite laboratories an option that should
be carefully evaluated, in consultation with the appro-
priate regulatory authority, as a possible way to re-
duce costs associated with chemical analysis. Such
methods can be used in two ways: (1) as an alternative
to sending samples to a laboratory where EPA-approved
or EPA-accepted methods can be used in the field or in
an on-site laboratory, and (2) for process control.
Most standard methods for sampling metals require use
of flame or graphite furnace atomic absorption spectros-
copy or inductively coupled plasma (ICP) atomic emis-
sion spectrometry, which require specialized training for
use. Laboratory analysis of arsenic, chromium, and
nickel in a sample of sludge can be expected to cost as
much as $80 to $85. In contrast, semiquantitative col-
orimetric tests, which often are able to detect concen-
trations in sub-ppm levels, are available for many metals
at a cost of less than $1.00 per sample. Table 10-5
identifies detection limits for a number of colorimetric
methods (field screening methods) for arsenic, chro-
mium, nickel, and nitrate, the main inorganic pollutants
of interest in sewage sludge placed on an active sewage
sludge unit. The Quant tests all use test strips that
change in color in response to a concentration of the
analyte being tested. EM Quant, Aquaquant, and Micro-
quant tests involve visual matching with color charts or
wheels. Spectroquant and Reflectoquant tests give
quantitative results using spectrophotometric measure-
ments. Hach tests use chemical reagents, often in com-
bination with digestion procedures, yield quantitative
measurements using a spectrophotometer. Hach (1991,
1992) provides detailed information on test procedures
for waste and water analysis, respectively.
Table 10-5 provides summary information on other types
of field-portable instruments. Ion-selective electrodes
(ISE) able to measure concentrations of nitrate down
to concentrations of 0.1 ppm and approved by U.S.
EPA for monitoring drinking water quality is planned
for publication in the Federal Register by the end of
1994. Laboratory analysis of water samples for nitrate
generally cost around $25 per sample. For an initial
investment of $1,500 to $2,500 for a nitrate electrode,
reference electrode, and meter, reagents for ISE tests
can be expected to cost from $0.50 to,$1.50 depending
on whether buffering solutions and reagents to reduce
interference from the presence of other species are used.
10.4 Media-Specific Monitoring
Considerations
10.4.1 Sewage Sludge Characterization
Number of Samples. Monitoring of arsenic, chromium,
and nickel is required when surface disposal of sludge
is conducted without use of a liner and leachate collec-
tion system to protect ground water. The regulation un-
der 40 CFR 503.23 establishes pollutant limits for these
metals based on distance from the boundary of the
active sewage sludge unit to the property line of the
surface disposal site (see Table 3-5 in Chapter 3). Sam-
pling of sludge is required at the frequency specified in
Table 10-2, based on the annual amount of sludge dis-
posed. The minimum number of samples required to
show that concentrations of arsenic, chromium, and
nickel comply with the applicable pollutant limits in Table
10-6 at a 90 percent confidence interval can be readily
calculated if the average concentration and the standard
deviation of the historical sample set is known. The
following simple equations are used for this procedure:
(Eq. 10-1)
Sample Mean (X) =
Sum of Data Values
n
(Eq. 10-2)
Standard Deviation(s) =
n(Sum of Squared Data Values) - (Sum of Data Values)
(Eq. 10-3)
Number of Samples =
(Constant T)2s2
(Regulatory Limit - X)2
where:
n = number of data values
Constant T = appropriate value from Table 10-7
Pollutant Limit = applicable value in Table 10-6 or
permit-specific value
The following steps are required to calculate the mini-
mum number of samples in a year to demonstrate com-
pliance with the pollutant limits for a sewage sludge:
Step 1. Calculate the mean and standard deviations for
arsenic, chromium, and nickel using historical data using
Equations 10-1 and 10-2. If historical data are not avail-
able, Table 10-8 can be used to provide initial values.
Step 2. Determine the Constant T f rom Table 10-7 based
on the number of data values (n), and the appropriate
184
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Table 10-6. Analytical Methods for Sewage Sludge
Enteric Viruses
Fecal Cobform
Helminth Ova
Inorganic Pollutants
Salmonella sp. Bacteria
Specific Oxygen Uptake Rate
Total, Fixed, and Volatile Solids
Percent Volatile Solids Reduction Calculation11
ASTM Designation: D 4994-89, Standard Practice for
Recovery of Viruses from Wastewater Sludges, Annual
Book of ASTM Standards: Section 1 1 . Water and
Environmental Technology, ASTM, Philadelphia, PA, 1992.
Part 9221 E or Part 922 D, Standard Methods for die
Examination of Water and Wastewater, 1 8th edition,
American Public Health Association, Washington, DC, 1992.
Yanko, W.A., Occurrence of Pathogens in Distribution and
Marketing Municipal Sludges, EPA/600/1-87/014, 1987. PB
88-154273/AS, National Technical Information Service,
Springfield, VA; (800) 553-6847.
Test Methods for Evaluating Solid Waste, Physical/
Chemical Methods, EPA Publication SW-846, 3rd edition
(1986) with Revision 1. 2nd edition. PB 87-120291, National
Technical Information Service, Springfield, VA. 3rd edition
Doc. No. 955-001-00000-1, Superintendent of Documents,
Government Printing Office, Washington, DC.
Part 9260 D, Standard Methods for Examination of Water
and Wastewater, 18th edition, American Public Health
Association, Washington, DC, 1992; or, Kenner, B.A. and
H.P. Claik, Detection and Enumeration of Salmonella and
Pseudomonas aeruginosa, J. Water Pollution Control
Federation, 46(9):2163-2171, 1974.
Part 2710 B, Standard Methods for the Examination of
Water and Wastewater, 18th edition, American Public
Health Association, Washington, DC, 1992.
Part 2540 G, Standard Methods for the Examination of
Water and Wastewater, 18th edition, American Public
Health Association, Washington, DC, 1992.
Environmental Regulations and Technology — Control of
Pathogens and Vectors in Sewage Sludge,
EPA/625/R-92/013, U.S. Environmental Protection Agency,
Cincinnati, OH, 1992; (614) 292-6717.
• These analytical methods are required by the Part 503 rate.
b This analytical raethcxl is provided as guidance in the Part 503 rule.
pollutant limits for all three metals from Table 10-6 or
site-specific values in the permit.
Step 3. Calculate the required number of samples for
each pollutant using Equation 10-3. The highest number
of the three should be used for purposes of sampling.
If the number of samples seems too high (which may be
the case if the national values from Table 10-8 are used),
several options may be available to reduce the number
of samples: (1) during the design stage, it may be pos-
sible to increase the distance from the boundary of an
active sewage sludge unit to the less stringent surface
disposal site property line if the distance is less than 150
ft, allowing recalculation of Equation 10-3 with pollutant
limits (Table 10-6); or (2) collect a number of samples at
relatively short intervals (days or weeks) and repeat
Steps 1 through 3 above to see if a larger historical
sample size reduces the number of samples required as
long as the frequency of monitoring in Part 503 is met.
As the difference between the average concentration of
a pollutant and the pollutant limit decreases, the number
of required samples to demonstrate compliance in-
creases. When this difference is small, the number of
required samples might be so large as to make monitor-
ing prohibitive. In such cases, the use of a liner and
leachate collection system should be evaluated. Also, if
the historical data indicate the pollutant limits cannot be
achieved (e.g., mean chromium values for 100 MGD
facilities in Table 10-8 exceeds the maximum allowed
pollutant concentration in Table 10-6), use of a liner and
leachate collection system is likely to be required.
Sample Collection. For "dry" sewage sludge (40 per-
cent solids) sampling is best done when it is being
transferred, usually on conveyors. U.S. EPA (1993a,
1994a) provide more detailed guidance on specific
sludge sample collection procedures. The most conven-
ient and most accurate scheme for sampling sludge will
generally be to sample haul truck loads at a frequency
that obtains the minimum number of samples calculated
using Equation 10-3 assuming the Part 503 frequency
of monitoring requirement is met. This frequency can be
determined by dividing the annual tonnage or cubic
yards of sludge by the calculated number of samples to
185
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Table 10-7. Tabulated Values of Constant T for Evaluating Sludge for 90 Percent Confidence Interval
.*yVi*%^?i«^ffiyg$-ri&tffi^
liM^ii^^^^^^^^
z
3
4
5
6
7
8
9
10
11
12
13
14
IS
16
17
18
19
20
21
22
23
24
25
26
23
30
inf.
y^&i&ijtii^^
K !*T^;5!;;SS?v?^ '; - •- * P*^* -{;*:?"$^£">!:::
6.314
2.920
2.353
2.132
2.015
1.943
1.895
1.360
1.S33
1.312
1.796
1.782
1.771
1.761
1.753
1.746
1.74,0
1.734
1.729
1.725
1.721
1 . 717
1.714
1.711
1.708
1.703
1.699
1.645
determine how often haul trucks or spreaders should be
sampled. For example, if 250 cubic yards of sewage
sludge are hauled to the site in a year, in haul trucks with
a 25 cubic yard capacity, and ten samples are required,
then a representative sample from each truck load
would be required. If half that amount was hauled in a
year, then two representative samples representing the
front and back half of each truck would be required.
10.4.2 Ground-Water Monitoring
Monitoring for nitrates in ground water at sewage sludge
surface disposal sites is required unless a certification
is made by a ground-water scientist that ground water
will not be contaminated by the disposal of sewage
sludge at the site (usually an option only if the site has
a liner and leachate collection system). If only nitrate
must be monitored (i.e., based on sludge or site charac-
teristics the regulatory authority does not require moni-
toring of other pollutants), it may be possible to use
drive-point monitoring well installations that are less
expensive than standard installations, as discussed
later in this section. In-house sample analysis using
nitrate ion-selective electrodes also may be an economi-
cally attractive alternative to sending samples to a labo-
ratory for analysis (see Section 10.3.6). The discussion
that follows assumes that only nitrate is being monitored
for regulatory reporting purposes and that the site rep-
186
-------
Table 10-8. Alternative Values for Calculating Required Number of Sludge Samples for Metals Monitoring
Pollutant Flow Group (MGD) Mean (mg/kg) Standard Deviation
Arsenic
Chromium
Nickel
>100 .
10 to 100
1to10
<1
>100
10 to 100
1 to 10
<1
>100
10 to 100
1 to 10
<1
7.71
12.08
9.72
9.93
461.41
281.40 ,
160.57
102.77
90.30
81.96
48.36
39.90
5.58
17.04
10.91
20.24
682.09
503.53
286.16
338.99
113.19
108.17
49.23
101.25
1.708
1.645
1.645
1.645
1.708
1.645
1.645
1.645
1.708
1.645
1.645
1.645
Source: Table 1-11, 55 FR 47229-47231, November 9, 1990.
resents a Type I hydrogeologic setting (Section 6.4.3).
If additional pollutants must be monitored, or aquifer
materials are not suitable for drive-point installations,
conventional monitoring well design should be followed,
as covered in ASTM (1990), U.S. EPA (1991 a), Nielsen
and Schaila (1991), and references in Table 6-7 in Chap-
ter 6. Use of drive-point installations for permanent
monitoring wells is still a relatively new concept in regu-
latory applications, so the appropriate regulatory
authorities should be consulted and provided any nec-
essary additional information to demonstrate that such
installations are an acceptable alternative to conven-
tional monitoring well installations.
Monitoring Network Design. Figure 10-1 summarizes
the process for designing a ground-water monitoring
system. The flow net analysis described in Section 6.5.2
provides a basis for selecting locations for background
monitoring wells and downgradient wells for detection
monitoring. For a simple Type I hydrogeologic setting,
monitoring wells would be set in the unconfined aquifer
with a minimum of two upgradient background monitor-,
ing wells (Figure 10-2), with the location and number of
downgradient monitoring wells depending on flow paths
and the size of the site and any specific regulatory
requirements addressing the number of wells. Flow net
analysis will guide the depth of monitoring wells and the
length of well screen to be used. As noted in Section
6.5.2, failure to use flow net analysis for placement of
monitoring wells and determining screened intervals can
easily result in samples that miss any pollutant plume
that develops.
Monitoring Well Installation. Typical monitoring well
installations in unconsolidated materials are drilled us-
ing a hollow-stem auger and constructed of PVC pipe
and well screen with filter-pack and grouting to seal the
annular space around the well pipe (ASTM,1990). If
nitrate is the only analyte of interest for ground-water
monitoring, as specified in the Part 503 regulation, then
alternative, less-expensive approaches might be able to
satisfy monitoring requirements. Sample bias as a result
of sorption or leaching of well screen and casing mate-
. rials is not a concern with nitrate because it is an anioh,
which means that small-diameter (typically 1 inch or less
outer diameter) metal drive pojnts and casing materials
can be used for installation of monitoring wells in uncon-
solidated materials. Basic elements of such an installa-
tion include: (1) a slotted drive point (stainless steel is
generally preferable for permanent installations be-
cause it is more resistant to corrosion); (2) a metal
casing that is either cut to length or added as extensions
until the desired depth is reached; and (3) a cap and
protective containment structure to prevent accidental
damage to the aboveground portion of the installation.
Possible additional elements of the installation many
include: (1) filter material, such as Vyon, to prevent soil
particles from entering the openings in the drive point
or use of porous stainless steel (10 to 20 micron open-
ing), and (2) tubing that runs inside to the.casing of the
welj point to eliminate contact between sample water
and the casing.
Methods of installation include the methods and equip-
ment described in Section 6.4.3 in Chapter 6 for instal-
lation of piezometers: (1) handheld power driver (Figure
6-2), (2) hydraulic probes (Figure 6-3), (3) hand-oper-
ated weighted drivers (Figure 6-8a), and (4) crank-driven
drivers (Figure 6-8b). In addition, vibratory drive meth-
ods that adapt high-frequency hammer drill technology
can be used for very rapid installation of pre-cut riser
sections up to a maximum length of 21 ft (Figure 10-3).
Depths of 30 ft can often be attained in nongravelly
unconsolidated materials using the methods described
187
-------
en
1
I
w
en
I
a*
1
en
d
u
I
Z
T
CONCEPTUAL
MODEL
FLOW NET
CONSTRUCTION
PLOT FACILITY
FEATURES
SELECT TARGET
MONITORING
ZONES
LOCATE
BACKGROUND
WELLS
LOCATE
DOWNGRADIENT
WELLS
VERIFY
LOCATIONS
INSTALL
DETECTION
MONITORING
WELLS
TEST
SYSTEM
GEOLOGY / HYDROGEOLOGY
• Surfac«seotogy (topography and type /depth of oveiburden
• Litnology and thickness of aquifer
• Type of geologic formation (local stratigraphy and structure)
• Recharge/ discharge areas
* Aquifer/confining unit(s) hydraulic conductivity and porosity
GROUND-WATER FLOW DIRECTIONS
Piezometeric anoYor potwttiorrotrie heads
Relative hydraulic heads between units
Three-dimensional flow directions using flow lines and equipotentials
Interconnection of aquifers
rates of ground-water movement
FACILITY FEATURES
• Bast map features
• Crosa-«aetians with lithology
• Facility basegrades established and compared with now paths
TARGET MONITORING ZONES
• Uppermost aquifer established
• AH reasonable Row paths identified
AMBIENT WATER QUALITY
• Upgradient design - simple geology and heads
• Background Design - Complex geology or heads
• Number should have statistical basis
BASIS FOR DESIGN
• Geology and permeable awies
• Row net analysis
• Target monitoring zones
• Fadity waste boundaries
LOCATION CRITERIA
• State and Federal requirements
• Permit requirements
• Between waste areas and downgradkmt receptore
HELD INSTALLATION OF WELLS
Use ASTM standards (D-15092)
Update conceptual nyaro^jeotogtc model
Document Installation
TEST AND OPERATE SYSTEM
• Performance test all welte
• Use operation and mamanee procedures
• Close and decommission inoorrectty placed wells
Figure 10-1. Flow diagram of monitoring system design (Sara, 1994).
188
-------
SELECTION OF BACKGROUND
WEtl SAMPLING SCHEME
USE ALL HISTORIC
PARAMETER VALUES
2 YEAR FIXED
HISTORICAL WINDOW
2 YEAR MOVING
WINDOW
8 OR MORE BACKGROUND WELLS IN SYSTEM
» Calculate a Haw Totoranea Interval Each Quarter
4 to 7 WE
2 to 4 WEI
1 BACKGROUND
WELL IN SYSTEM
NUMBER OF
BACKGROUND WELLS
IN SYSTEM
WITH 4 TO 7 BACKGROUND WELLS IN SYSTEM
•*" • Conduct Quarterly Monitoring
• Calculate a Yoariy Totorenc* Interval
2 TO 4 BACKGROUND WELLS IN SYSTEM
» Quarterly Monitoring Until 19 Sampfe* ara Taken
• UaaaHHiatoricValuaafQrTolanmc* Intervala
INSTALL ADDITIONAL "UPGRADIENT"-
BACKGROUND WELLS OR YOU WILL NEVER
PASS ANY STATISTICAL TEST HI
RCCOMMENDKD BACKGROUND SAMPLING SCHEME
Figure 10-2. Guidelines for background well sampling based on number of wells (Sara, 1994).
189
-------
Screen
MicroWell Schematic
Diagram
2" x 0.015"
Screen Slots
Sump
Drive
Point
Figure 10-3. Micro Well schematic diagram; standard pipe Is
0.62 Inches Internal diameter and 0.82 Inches
outer diameter (courtesy of Pine & Swallow Asso-
ciates).
above. In unconfined sandy aquifers, depths of 100 ft
are readily obtainable. Vibratory drive installations have
penetrated to a maximum depth of 180 ft (personal
communication, John Swallow, Pine & Swallow Associ-
ates, Groton, MA, April 1994). Solinst Canada's product
literature reports that a Waterloo drive-point piezometer
using a power-driven drive-hammer has been installed
at a depth of 275 ft in lacustrine clay in New Mexico.
Costs of drive-point monitoring well installations can be
expected to range from 30 to 50 percent lower than
conventional hollow-stem auger monitoring well instal-
lations. Table C-1 in Appendix C identifies manufactur-
ers and distributors of well and piezometer drive points
and drive equipment.
Sample Collection. The narrow diameter of the above
monitoring well installations restricts sample collection
to two main methods: (1) peristaltic suction lift pump for
depths of 25 or 30 ft; (2) WaTerra inertial pump to depths
of 100 ft (depths up to 250 feet can be sampled in 2- to
4-in. wells); (3) portable Solinst triple tube gas-drive
sampler to depths up to 150 ft; and (4) small-diameter
bailers (any depth). Specialized sampling techniques
include (1) the BAT system, which uses evacuated sam-
ple containers and a disposable double-ended hypoder-
mic needle for sample collection, and (2) the Waterloo
drive-point double valve pump, which includes a dedi-
cated positive displacement gas-drive sampler inside
the drive point device.
Because drive-point installation results in minimal dis-
turbance of the aquifer materials, if any, well develop-
ment is required before samples are collected. If the
drive point includes filter material, then well develop-
ment should not be necessary. If the drive point is open
slotted, then some soil grains less than the diameter of
the slotting can enter the point, especially if vibratory
drilling is used. For shallow installations (less than 25 ft)
this material can be removed by using a peristaltic pump
and inserting polyethylene tubing to the sediment/water
interface. Deeper installations will require use of a bailer
or WaTerra type inertial pump and surging action to
suspend the sediment for collection in the bailer.
The narrow diameter of the drive pipe (generally less
than 1 inch) means that drive-point installations will have
less stagnant water in the well between sampling
events, and the lack of filter pack or grout means that
aquifer chemistry outside the well is minimally affected
compared to conventional monitoring well installations.
Consequently the amount of time required for purging
before a sampling event also will be reduced. While
purging, pH, conductance, and temperature should be
monitored until they reach a consistent endpoint (no
upward or downward trend), at which point the sample
should be taken. Table C-1 in Appendix C identifies
sources of field instrumentation for ground-water sam-
pling. If nitrate ion-selective electrodes are used to ana-
lyze samples, multiparameter instruments are available
that would allow monitoring of purge parameters and
measuring nitrate concentration with the same meter.
70.4.3 Leachate and Surface Water
Monitoring
If a liner and leachate collection system are used to
prevent migration of pollutants into the ground water, the
disposition of the leachate will determine what kind of
monitoring will be required. Discharge as a point source
to surface waters will require an NPDES permit, with the
permit specifying what parameters must be monitored.
Table 10-1 identifies commonly monitored parameters.
As discussed in Section 10.3.6, depending on the pa-
rameters that must be monitored, use of wet chemistry
field test kits or a small onsite laboratory may be a
cost-effective alternative to sending samples to an out-
side laboratory. For example, there are 6 Hach methods
that are U.S. EPA approved, and 35 Hach methods that
are accepted by U.S. EPA for purposes of NPDES re-
porting (Hach Company, 1989).2 The appropriate regu-
latory authority should always be consulted to determine
whether a specific proposed method would be accepted
for regulatory reporting. If leachate is discharged to a
As noted in Section 10.3.6, the manufacturer test kits and equipment
should be contacted for information on the current status of EPA
acceptance or approval and asked to provide the appropriate docu-
mentation.
190
-------
POTW, some monitoring might be required or appropri-
ate for process control. Because precise measurements
are usually not required for this purpose, use of col-
orimetric test strips as described in Section 10.3.6 might
be a useful option. ',
Surface runoff from the sludge surface disposal site that
is collected and discharged as a point source will require
an NPDES permit. As with leachate, the permit will
specify what parameters are to be monitored. It may be
desirable to monitor any surface runoff from the active
sewage sludge unit that is not controlled as a point
source to see if pollutants of concern are moving offsite.
Use of Quant test strips (Table 10-5) would be'a rela-
tively inexpensive way to determine the concentration of
arsenic, chromium, nickel, and nitrate in surface runoff.
10.4.4 Monitoring Air for Methane Gas
Whenever sewage sludge placed on an active sewage
sludge unit is covered daily or at closure, continuous
monitoring of air for methane gas is required in all
structures within the site properly line and at site prop-
erty lines. Methane gas concentrations within any struc-
ture must be less than 25 percent of the lower explosive
limit (LEL), which is the lowest percentage by volume of
methane gas in air that supports a flame at 25°C and
atmospheric pressure. For methane, the LEL is 5 per-
cent. At the site property line, the LEL is the regulatory
limit (i.e., concentrations are not allowed to exceed the
LEL in air at the property line), (See Section 7.8.2 for
additional information on control of explosive gases con-
trols.)
Two main technologies are available for methane gas
monitoring: (1) metal oxide sensors (MOS), also called
catalytic oxidation, semiconductor, or solid state detec-
tors; and (2) Pellistor/Wheatstone Bridge sensors. The
first type tend to cost less but are less accurate (i.e.,
usually do not provide quantitative readings of concen-
trations), more difficult to calibrate, and are quite sensi-
tive to changes in humidity. Pellistor/Wheatstone Bridge
sensors are recommended for use when monitoring
methane gas concentrations in air inside a structure.
The electrical response of the Wheatstone bridge is
linear with concentration, which allows accurate meas-
urement at low concentrations. Sensors with a 4 to 20
milliamp (mA) signal range are recommended. Calibrat-
ing the sensor so that 4 mA equals zero provides assur-
ance that the sensor is operating because any power
failure will result in a negative reading.
There are several rules of thumb for determining how
many sensors are required for a building. Smaller build-
ings with multiple rooms generally should have a sensor
for every 1,500 cu ft of volume. For larger, open build-
ings, spacing of sensors 100 to 150 ft on center will
generally be adequate. Sensors should be mounted on
the highest point of a ceiling, and if outside air circulates
through the structures, they should tend to be offset
toward the downwind side of the structure (generally the
east side). Sensors will provide maximum safety if they
are installed so that methane concentrations of 10 per-
cent LEL will cause a fan with a timer to automatically
turn on to improve air circulation (the timer prevents the
fan from being turned on and off repeatedly if concen-
trations fluctuate around 10 percent LEL). The sensor
should be designed to sound a horn or turn on a warning
light if methane concentrations reach 20 percent LEL so
that action can be taken to reduce methane levels be-
fore the 25 percent limit in the Part 503 regulation is
reached. Pellistor/ Wheatstone Bridge sensors should
be calibrated every 30 to 90 days to ensure proper
functioning. The installed cost of indoor installations for
Pellistor/Wheatstone Bridge sensors can be expected to
fall in the range of $1,000 to $1,500 per sensor.
Because methane gas is considerably less dense than
air (specific gravity 0.5 percent) outdoor methane gas
releases will tend to rise rather than travel laterally to
site property lines unless there are exceptionally strong
winds. It is highly unlikely that methane gas concentra-
tions will reach anything approaching the LEL at sewage
sludge surface disposal site property lines, but the most
likely place to measure maximum concentrations would
be downwind (generally east) of the area where sludge
amounts are thickest. Initially, a single installation at the
downwind point at which methane gas concentrations
are expected to be highest should be adequate. The
sensor should be set at about 6 ft above ground level
and will require electrical service unless the site is very
remote, in which case rechargeable batteries would be
required. The sensor should be set to sound an audible
alarm if methane gas concentrations reach 20 percent
LEL. If site property line sensor readings repeatedly
exceed 10 percent LEL, some consideration should be
given to installing additional sensors along the down-
wind perimeter.
Table C-1 in Appendix C provides a selective list of
manufacturers of gas monitoring instruments. The
March 1994 issue of Pollution Equipment News (8650
Babcock Blvd., Pittsburgh, PA 15237-9915; 800/245-3182)
provides a more detailed listing with information on gas
detection equipment available from more than 90 manufac-
turers. The gas detection selection chart, which is updated
annually, can be obtained by contacting Rimbach Publishing
at the location and phone number given above.
10.5 Analysis and Interpretation of
Sample Data
70.5.1 Sewage Sludge Characterization Data
When arsenic, chromium, and nickel concentrations are
monitored, each new set of sample results should first
be checked against the applicable limits in Table 10-8.
191
-------
Assuming that analytical results fall within acceptable
levels, the only other type of analysis is that at least once
a year the procedures described in Section 10.4.1
should be repeated adding in the previous year's ana-
lytical results to recalculate sampling frequency for the
upcoming year.
10.5.2 Ground-Water Sampling Data
As shown in Figure 10-2 a minimum of two background
monitoring wells are required for valid statistical com-
parison of background and downgradient monitoring re-
sults. If fewer than four background monitoring wells are
used, typically the case at sewage sludge surface dis-
posal sites, quarterly monitoring until 16 samples have
been taken is required before monitoring data results in
downgradient wells can be properly interpreted (Sara,
1994). The types of statistical tests to determine whether
nitrate has entered the ground-water system as a result
of sludge disposal would be the same as for a RCRA
facility and are described in U.S. EPA (1989a). U.S.
ERA'S GRITS/STAT software (U.S. EPA, 1992b) can be
used to store monitoring data and run the statistical tests
recommended in U.S. EPA (1989a). The required re-
sponse if nitrate contamination is detected will depend
on the background ground-water quality and policies of
the permitting agency.
10.5.3 Other Data
Leachate and surface water sampling data generally do
not require statistical analysis. If sampling is used for
NPDES reporting, then sample results are compared
against the limits specified in the permit. Sampling of
leachate for process control when discharged to a
POTW, as discussed in Section 10.4.3 might require
some simple statistical analysis to compute average
values and the range of values examined to see
whether they are within desired limits. Methane gas
monitoring systems in structures should be designed
to be self-regulating, as described in Section 10.4.4,
and will not normally require collection or analysis of
sensor readings.
10.6 References
1. American Public Health Association (APHA). 1992. Standard
methods for the examination of water and wastewater, 18th edi-
tion. Washington, DC.
2. American Society for Testing and Materials (ASTM). 1990. Rec-
ommended practice for design and installation of ground-water
monitoring wells in aquifers, Vol. 4.08. D5092-90. Philadelphia, PA.
3. Boulding, J.R. 1994. Description and sampling of contaminated
soils: A field guide, revised and expanded, 2nd ed. Chelsea, Ml:
Lewis Publishers.
4. Granato, T.C., and R.I.I. Pietz. 1992. Sludge application to dedi-
cated beneficial use sites. In: Luel-Hing, C., D.R. Zenz, and R.
Kuchenrither, eds. Municipal sewage sludge management: Proc-
essing, utilization and disposal. Lancaster, PA: Technomic Pub-
lishing Co. pp. 416-454.
5. Hach Company. 1992. Water analysis handbook, 2nd ed. Love-
land, CO: Hach Company. [See Appendix C for address and
phone number.]
6. Hach Company. 1991. Handbook for waste analysis, 2nd ed.
Loveland, CO: Hach Company. [See Appendix C for address and
phone number.]
7. Hach Company. 1989. Using Hach methods for regulatory report-
ing and process control. Loveland, CO: Hach Company. [See
Appendix C for address and phone number.]
8. Keith, L.H. 1992. Environmental sampling and analysis: A prac-
tical guide. Chelsea, Ml: Lewis Publishers. (In cooperation with
ACS Committee on Environmental Improvement.)
9. Nielsen, D.M., and R. Schaila. 1991. Design and installation of
ground-water monitoring wells. In: Nielsen, D.M., ed. Practical
handbook of ground-water monitoring. Chelsea, Ml: Lewis Pub-
lishers, pp. 239-331.
10. Sara, M.N. 1994. Standard handbook of site assessment for solid
and hazardous waste facilities. Boca Raton, FL: Lewis Publish-
ers.
11. Sieger, R.G., R.C. Carlson, L. Patterson, and G.J. Hermann.
1992. Ground water, soil, and vegetation monitoring for two land
application projects in Texas. In: The future direction of municipal
sludge (biosolids) management: Where we are and where we're
going. Poster session proceedings, Vol. II. Water Environment
Federation, pp. 163-172.
12. U.S. EPA. 1994a. POTW sludge sampling and analysis guidance
document, 2nd ed. Washington DC. [1st edition published 1989.
(NTIS PB93-227957)]
13. U.S. EPA. 1994b. Surface disposal of sewage sludge: A guide
for owners/operators of surface disposal facilities on the monitor-
ing, recordkeeping, and reporting requirements of the federal
standards for the use or disposal of sewage sludge, 40 CFR Part
503. EPA/831/B-93/002C.
14. U.S. EPA. 1993a. Preparing sewage sludge for land application
or surface disposal: A guide for preparers of sewage sludge on
the monitoring, recordkeeping, and reporting requirements of the
federal standards for the use or disposal of sewage sludge under
40 CFR Part 503. EPA/831/B-93/002a.
15. U.S. EPA. 1993b. RCRA ground water monitoring: Draft technical
guidance. EPA/530/R-93/001 (NTIS PB93-139350).
16. U.S. EPA. 1992a. Environmental regulations and technology:
Control of pathogens and vector attraction in sewage sludge
(including domestic septage) under 40 CFR Part 503.
EPA/625/R-92/013.
17. U.S. EPA. 1992b. User documentation: A ground-water informa-
tion tracking system with statistical analysis capability GRITS/
STAT, Version 4.2. EPA/625/11-91/002.
18. U.S. EPA. 1992c. Preparation of soil sampling protocols: Sam-
pling techniques and strategies. EPA/600/R-92/128 (NTIS PB92-
220532). (Supersedes 1983 edition titled: Preparation of soil
sampling protocol: Techniques and strategies, EPA/600/4-03/020
[NTIS PB83-206979].)
192
-------
19. U.S. EPA. 1991 a. Handbook of suggested practices for the design
and installation of ground-water monitoring wells. EPA/600/4-89/
034. (Also published in 1989 by National Water Well Association,
Dublin, OH, in its NWWA/EPAseries, 398 pp. Nielsen and Schalla
[1991] contain a more updated version of material in this hand-
book that is related to design and installation of ground-water
monitoring wells.)
20. U.S. EPA. 1991b. Description and sampling of contaminated
soils: Afield pocket guide. EPA/625/2-91/002.
21. U.S. EPA. 1991c. Geochemical sampling of subsurface solids
and ground water. In: Site characterization for subsurface reme-
diation (Chapter 9). EPA/625/4-91/026.
22. U.S. EPA. 1989a. Statistical analysis of ground-water monitoring
data at RCRA facilities, interim final guidance. EPA/530/SW-
89/026 (NTIS PB89-151047), plus September 1991 Addendum.
[Incorporated into GRITS/STAT.]'
23: U.S. EPA. 1989b. Soil sampling quality assurance user's guide,
2nd ed. EPA/600/8-89/046 (NTIS PB89-189864).
24. U.S. EPA. 1986. Test methods for evaluating solid waste, 3rd ed.
EPA/530/SW-846 (NTIS PB88-239223). First update, 3rd ed.
EPA/530/SW-846.3-1 (NTIS PB89-148076). 2nd edition was pub-
lished in 1982 (NTIS PB87-1200291); current edition and updates
available on a subscription basis from U.S. Government Printing
Office, Stock #955-001 -00000-1.
25. U.S. EPA. 1985. Practical guide for ground-water sampling.
EPA/600/2-85/104 (NTIS PB86-137304). Also published as ISWS
Contract Report 374, Illinois State Water Survey, Champaign, IL.
193
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Chapter 11
Recordkeeping, Reporting, and Management for Surface Disposal
11.1 General
This chapter describes the recordkeeping and reporting
requirements when sewage sludge is placed on a sur-
face disposal site under the Part 503 rule, including
records of costs and activities. Regulatory requirements
for recordkeeping are covered in Section 11.2. This
discussion covers requirements for owners/operators of
active sewage sludge units with, and without, liners and
leachate collection systems, and for preparers of sew-
age sludge. The U.S. EPA document, Surface Disposal
of Sewage Sludge: A Guide for Owners/Operators of
Surface Disposal Sites on the Monitoring, Recordkeep-
ing, and Reporting Requirements of the Federal Stand-
ards for the Use or Disposal of Sewage Sludge 40 CFR,
Part 503 (1994a), and U.S. EPA (1993b) outline addi-
tional information on the recordkeeping requirements for
operators of active sewage sludge units and preparers
of sewage sludge, respectively.
This chapter also discusses the management of surface
disposal sites, including management organization and
staffing/personnel. The management system required for
a surface disposal site will be influenced by such factors
as the type of active sewage sludge unit, the volume and
type of sludge received, and site conditions. The goals of
the manager of a sewage disposal site should be to oper-
ate the site in a manner that is economically sound and
adequately protects public health and the environment.
These goals must be carefully balanced as regulations
become more stringent and operating costs increase.
The management of a surface disposal site involves a wide
range of activities. The site manager is responsible for:
• Day-to-day operation
• Equipment maintenance and replacement
• Regulatory compliance
• Site security
• Public relations
• Personnel management and training
• Recordkeeping
• Fiscal management
11.2 Regulatory Requirements for
Recordkeeping
11.2.1 Part 503 Recordkeeping
Requirements for Owners/Operators
of Active Sewage Sludge Units With
Liners and Leachate Collection
Systems
Owners/operators of active sewage sludge units are
required to keep records of management practices and
applicable vector attraction reduction requirements.
They must also keep a certification statement as shown
in Figure 11-1. The records must be maintained for 5
years and be readily available to State and EPA inspec-
tors. The owners/operators should be aware that failure
to keep adequate records is a violation of the Part 503
regulation and subject to penalty under the Clean Water
Act (CWA).
11.2.1.1 Records of Management Practices
Owners/operators must ensure that the management
practices (requirements for the siting, design, and op-
eration of active sewage sludge units to ensure protec-
tion of human health and the environment) are met at
each active sewage sludge unit. In addition, compliance
with these practices must be documented in detailed
records and kept for 5 years. Compliance with siting and
design requirements must be documented only once.
Compliance with the operating requirements must be
recorded on a continual basis, the frequency of which
depends on the specific requirements.
Some of the information gathered to support one man-
agement practice may overlap with the information re-
quired for others. For example, geotechnical investigations
are required to demonstrate compliance with the re-
quirements for three management practices: seismic
impact zone, fault zones, and unstable areas. Geotech-
nical investigations, which are necessary for any con-
struction project, evaluate foundation soils and bedrock
and characterize the hydrogeology of a site. Maps or draw-
ings should be obtained or produced as part of compli-
ance with the management practices. A combination of
195
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"I certify, under penalty of law, that the management practices in §503.24 and
the vector attraction reduction requirement in [insert one of the requirements in
§503.33(b)(9) through §503.33(b)(l 1), if one of those requirements is met]
have/have not been met This determination has been made under my direction
and supervision in accordance with the system designed to ensure that qualified
personnel properly gather and evaluate the information used to determine that
the management practices [and the vector attraction reduction requirements, if
appropriate] have been met I am aware that there are significant penalties for
false certification, including the possibility of fine and imprisonment"
Signature
Date
Figure 11-1. Certification statement required for recordkeeping: Owner/Operator of surface disposal site (U.S. EPA, 1994b).
commercially available and customized maps and plans
can help demonstrate compliance.
Endangered or Threatened Species
Part 503 prohibits the placement of sewage sludge on
an active sewage sludge unit if it is likely to adversely
affect an endangered or threatened species or its des-
ignated critical habitat (see Section 4.2.1.1). The
owner/operator should retain all documentation to dem-
onstrate that the site was evaluated for potential effects
on endangered or threatened species and their habitat
and that necessary protective measures were identified
and implemented. For example, this documentation
should list endangered or threatened species in the area
or document that none exists and briefly describe how
the endangered or threatened species and its critical
habitat are protected.
Usually, documentation will need to be performed only
once. If the active sewage sludge unit begins to pose a
risk to endangered or threatened species, however, the
owner/operator should contact the permitting authority
or the Fish and Wildlife Service.
Base Flood Flow Restrictions
Part 503 prohibits an active sewage sludge unit from
restricting the flow of a base flood (see Section 4.2.1.2).
The following types of information may be used to de-
scribe how this management practice is met:
• A flood plain insurance rate map (available from the
Federal Emergency Management Agency) with the site
location accurately marked to demonstrate whether
it is within the 100-year floodplain. Other sources of
this information include the U.S. Army Corps of Engi-
neers, the U.S. Geological Survey (USGS), Bureau
of Land Management, Tennessee Valley Authority, and
local and State agencies.
• If the unit is in the 100-year floodplain, the design
details and management practices that will prevent
restriction of the flow of the base flood, including a
plan view, a cross section of the unit, and calculations
used to determine that the site will not restrict the
base flood flow.
• If the unit is in the 100-year floodplain, evaluation of
the impact of the unit based on predictive models,
such as the HEC series generated by the U.S. Army
Corps of Engineers.
Seismic Impact Zones
Part 503 requires active sewage sludge units located in
seismic impact zones to be designed to withstand the
maximum recorded ground level acceleration (see Sec-
tion 4.2.1.3). The following types of information can be
used to help demonstrate compliance with the seismic
impact zone management practice:
• A seismic map, available from State or local agen-
cies, with the site location marked on the map.
• Reports from State or local agencies on earthquake
activity, including the maximum recorded horizontal
ground level acceleration (as a percentage of the accel-
eration due to gravity (g), g=9.8 m/s2) (this information
is probably contained in any reports on earthquake ac-
tivity obtained from State or local agencies).
• A site inspection that focuses on slopes that may
have had the toe removed, water seeps from the
base of a slope, less resistant strata at the base of
a slope, posts and fences that are not aligned, utility
poles with sagging or too tight wires, leaning trees,
cracks in walls and streets, etc.
• If the active sewage sludge unit is located in a seismic
impact zone, documentation on design specifications
to accommodate the ground motion from earthquakes,
such as shallower unit side slopes, more conserva-
tive design of dikes and runoff controls, and contin-
gency plans for leachate collection systems.
• Design plans for the unit indicating the maximum
ground motion that unit components are designed
to withstand, including foundations, embankments,
196
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leachate collection systems, liners (if installed), and
any ancillary equipment that could be damaged from
seismic shocks.
• Certification by an engineer with seismic design and
geotechnical experience that the unit is designed to
withstand the maximum recorded horizontal ground
level acceleration.
Fault Zones
Part 503 prohibits locating an active sewage sludge unit
within 60 meters of a fault that has had displacement
(i.e., movement) during Holocene time (typically within
the last 11,000 years) (see Section 4.2.1.3). Documen-
tation to support this management practice may-include
the following:
• A Holocene fault map (available from Jocal .planning
or State geological agencies or the USGS) with the
site location marked. In 1978, the USGS published a
map series identifying the location of Holocene faults
in the United States (Preliminary Young Fault Maps
[USGS, 1978]. For areas along Holocene faults, an
investigation of the site and surrounding areas should
be performed to determine if movement has occurred
since 1978.
• A report on the area investigation of the site, empha-
sizing the location of faults, lineaments, or other features
associated with fault movement, such as offset streams,
cracked culverts and foundations, shifted curbs, es-
carpments, or other linear features.
• A geotechnical report on the site indicating the pres-
ence or absence of any faults or lineaments.
Unstable Areas
Part 503 also prohibits locating active sewage sludge
units in unstable areas (see Section 4.2.1.3). The follow-
ing information may be used to demonstrate that an
individual active sewage sludge unit is not located in an
unstable area:
• A one-time detailed geotechnical and geological
evaluation of the stability of foundation soils, adjacent
manmade and natural embankments, and slopes (may
include both in situ and laboratory test evaluations).
• A one-time evaluation of the ability of the subsurface
to support the active sewage sludge unit adequately,
without damage to the structural components. If the
evaluation indicates that an active sewage sludge unit
is located in an unstable area, the unit must close.
Wetlands
Part 503 prohibits the location of an active sewage
sludge unit in a wetland, unless a permit is issued
pursuant to either Section 402 or 404 of the Clean Water
Act, as amended (see Section 4.2.1.4). The following
types of information may be necessary to demonstrate
compliance with wetland restrictions:
• The location of the site on a wetlands delineation
map, such as a National Wetlands Inventory map,
Soil Conservation Service soil map, or a wetlands
inventory map prepared locally.
• A permit or permit application for a Section 402 or
404 permit.
• A description of a wetlands assessment conducted
by a qualified and experienced, multidisciplinary team,
including a soil scientist and a botanist or biologist.
Storm Water Runoff
Part 503 requires that runoff jfrqm an active sewage
sludge unit be'collected and dispose'd of*in accordance
with National Pollutant Discharge Elimination System
(NPDES) requirements and any other applicable re-
quirements (see Section 7.2.1.1). In addition, the runoff
collection system must be designed to handle the runoff
from a 24-hour, 25-year storm event. The following types
of information may be used to support compliance with
this management practice:
• Copies of the NPDES permit and any other permits.
• A description of the design of the system used to
collect and control runoff, including plan view, draw-
ing details, cross sections, and calculations showing
that the system has the capacity to collect the runoff
volume anticipated from a 24-hour, 25-year storm
event.
• A calculation of peak runoff flow, including data
sources and methods used to calculate the peak run-
off flow from a 24-hour, 25-year storm event.
• A description of inspection and maintenance required
for the system.
• A description of the procedures for managing liquid
discharges and complying with NPDES and other
requirements.
Leachate Collection and Control
If an active sewage sludge unit has an appropriate liner
and leachate collection system, the owner/operator
must document that the leachate collection system is
properly operated and maintained while the unit is active
and for 3 years after closure of the sewage sludge unit
(see Section 7.2.1.2). Documentation must also indicate
that the leachate is disposed of properly. The following
types of information may be used to demonstrate com-
pliance with this management practice:
• Detailed material specifications for the liner, including
drainage layer, filter layer, piping, and sumps.
197
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• A description of the leachate collection system de-
sign, leak detection capability, and capacity for re-
moval of leachate and liquid from the system.
• Design details, including layout of system and com-
ponents shown in plan view and cross section and
spacing and configuration of pipes, sumps, pumps,
drainage plans.
• Test results demonstrating system compatibility with
sewage sludge and leachates for all system compo-
nents and materials.
• A description of inspection and maintenance sched-
ules and procedures.
• An operational plan describing the method of treatment
and disposal of leachate and schedules for disposal.
• Records of collection, treatment and disposal activities
that demonstrate compliance with applicable require-
ments. For example, volume collected, monitoring
data on treated leachate, volume disposed of (where
and when).
Monitoring Air for Methane Gas
Air must be monitored continuously for methane gas
when an active sewage sludge unit is covered daily
(see Section 10.4.4). When a final cover is placed on
a sewage sludge unit, air must be monitored continu-
ously for methane gas for 3 years after closure of the
sewage sludge unit. The following types of information
may be used to demonstrate compliance with this man-
agement practice:
• A description of the system design, including plan
drawing and calculations showing that the system
can monitor air for methane gas concentrations.
• Design details of the site, including gas monitoring
locations, spacing, and layout.
• Descriptions of air monitoring, alarm systems, emer-
gency procedures, emergency contingency plans,
system maintenance schedules, and any known
methane gas mitigation.
• Results of methane gas monitoring, including the
maximum and average levels recorded.
Food/Feed/Fiber Crops Prohibition
Growing food, feed, or fiber crops on any active sewage
sludge unit is prohibited, unless explicitly authorized by
the permitting authority (see Section 9.2.1.1). The fol-
lowing types of information can be used to demonstrate
compliance with this management practice:
• Approval by the permitting authority if crops are being
grown on the site.
• A listing of any vegetation on the unit.
• A description of procedures to ensure adherence to
the crop use restrictions.
Grazing Prohibition
Part 503 prohibits grazing of animals on active sewage
sludge units, unless specifically authorized by the per-
mitting authority (see Section 9.2.1.1). The types of
information that can be used to demonstrate compliance
with the grazing restriction include the following:
• Approval by permitting authority if animals are being
grazed at the site.
• If the location of the surface disposal site and the
land use of surrounding properties exclude or limit
grazing, then the only necessary documentation or
records may be the certification statement required
by the regulation that the management practices are
being met.
* If the owner/operator has to install animal restriction
devices (such as grates at gate entrances or electric
fencing), records should be kept on the design, in-
stallation, and maintenance of the devices and a site
map showing the locations of the devices.
Public Access Restrictions
Part 503 requires the owner/operator to restrict public
access to active sewage sludge units and to closed units
for 3 years after closure (see Section 7.2.1.4). The
following types of information can be used to demon-
strate compliance with the public access restrictions:
• A site map, showing the access control locations
(e.g., placement of signs, fences and gates, and
natural barriers).
• A description of access restriction measures, such as
placement of vehicle barriers, signs, and construction
plans for the placement and configuration of fences
and gates.
• Language on warning signs.
• An inspection schedule for the access controls and
repair procedures.
• Schedules for security guard postings or security
inspections.
Prohibition of Ground-Water Contamination
Part 503 states that sewage sludge placed on an active
sewage sludge unit cannot contaminate an aquifer (see
Section 4.2.1.6). Compliance with this management
practice may be demonstrated in either of the following
two ways:
• Certification by a qualified ground-water scientist that
sewage sludge placed on the active sewage sludge
unit does not contaminate the aquifer. This should
198
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include a report demonstrating that the design, con-
struction, and operation of the liner/leachate collec-
tion system or the geology of the site is sufficient
to retard liquid flow during the active life and post-
closure period.
• Providing ground-water monitoring data. These data
should include both baseline monitoring data on the
aquifer obtained prior to placing sewage sludge in the
unit, and ground-water monitoring data collected pe-
riodically throughout the life of the active sewage
sludge unit.
The regulation requires this management practice to be
met by either certification of a qualified ground-water
scientist or the results of a ground-water monitoring
program. The scientist must have a bachelor or post-
graduate degree in the natural sciences or engineering
and have sufficient training and experience (as demon-
strated by State registration or professional certification)
in ground-water monitoring, pollutant fate and transport,
and corrective actions.
11.2.1.2 Part 503 Recordkeeping Requirements
for Vector Attraction Reduction
As discussed in Section 3.4.2.3, there are i1 options to
comply with the vector attraction reduction require-
ments. Options 1 through 8 are performed by the person
who prepares the sewage sludge (see Section 11.2.3).
Options 9 though 11 are performed by the owner/
operator of the surface disposal site. Whenever one of
options 9 through 11 is used, the owner/operator must
certify whether the vector attraction reduction require-
ment is met. In addition, the owner/operator must keep
records containing a description of how vector attraction
reduction is met. The description should be supported
by documentation of any activity used to achieve the
vector attraction,reduction. Records of the certification
and description must be kept for at least 5 years.
Option 9—Sewage Sludge Injected Below Surface
of the Land
Option 9 requires that the sewage sludge be injected
below the surface of the land and that no significant
amount of sewage sludge be visible within 1 hour of
injection. If the sewage sludge meets the Class A patho-
gen reduction requirements, injection must take place
within 8 hours after being discharged from the pathogen
reduction process. Documentation on compliance could
include a field notebook with entries describing how
sewage sludge is injected below the land surface, the
class of pathogen reduction achieved, how much time
elapses between the pathogen reduction process and
injection (if Class A), and observations on the amount of
sewage sludge present on the land surface 1 hour after
sewage sludge was injected.
Option 10—Sewage Sludge Incorporated Into the Soil
If sewage sludge is going to be incorporated into the soil
for vector attraction reduction, the sewage sludge must
be incorporated within 6 hours of placement on the
active sewage sludge unit. If the sewage sludge is Class
A, it has to be placed on the unit within 8 hours after
being discharged from the pathogen reduction process
and then incorporated into the soil within six hours after
placement. There is no time period requirement for
Class B sewage sludge. Documentation on compliance
could include a field notebook with entries describing
how the sewage sludge was incorporated and the class
of pathogen reduction achieved. If the sewage sludge is
Class A, notes should include the date and time (hour
of day) the sewage sludge was discharged from the
pathogen reduction process and the date and time (hour
of day) the sewage sludge was incorporated into the soil.
Option 11—Sewage Sludge Covered With Soil or
Suitable Material
Under option 11, the sewage sludge is covered with soil
or other material at the end of each operating day.
Option 11 meets vector attraction reduction require-
ments and pathogen reduction requirements. In con-
trast, when options 9 or 10 are used, either the Class A
or Class B pathogen reduction requirements have to be
met. Documentation on compliance with option 11 could
include a field notebook describing when and, how the
soil or another material is placed over the sewage
sludge at the end of each operating day, the thickness
of the cover, and the type of cover material used.
11.2.1.3 Records of Pathogen Reduction
Part 503 does not impose recordkeeping requirements
for pathogen reduction on the site owner/operator. Be-
cause the preparer is responsible for pathogen reduc-
tion, the preparer must document compliance (see
Section 11.2.3).
11.2.2 Part 503 Recordkeeping
Requirements for Owners/Operators
of Active Sewage Sludge Units
Without Liners and Leachate
Collection Systems
Owners/operators of active sewage sludge units without
liners and leachate collection systems must comply with
all of the Part 503 recordkeeping requirements for the
management practices that encompass design, siting,
and operation, as well as for vector attraction reduction,
as described in Section 11.2.1 above. In addition, the
Part 503 regulation requires owners/operators of active
sewage sludge units without liners and leachate collec-
tion systems to maintain records documenting the con-
centration of pollutants (arsenic, chromium, and nickel)
in the sewage sludge if the active sewage sludge unit
199
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boundary is less than 150 meters from the property line
of the surface disposal site or if site-specific pollutants
have been approved by the permitting authority. Docu-
mentation of sampling and analysis for pollutant concen-
trations should include the following information:
• Date and time of sample collection, sampling loca-
tion, sample type, sample volume, name of sampler,
type of sample container, and methods of preserva-
tion (including cooling).
• Date and time of sample analysis, name of analyst,
and analytical methods used.
• Laboratory bench sheets indicating all raw data used
in analyses and calculation of results.
• Sampling and analytical QA/QC procedures.
• Analytical results expressed in dry weight.
11.2.3 Part 503 Recordkeeping
Requirements for the Preparer of
Sewage Sludge for Placement on a
Surface Disposal Site
The preparer of sewage sludge placed on an active
sewage sludge unit must develop and keep the following
information for 5 years (U.S. EPA, 1994b):
• The concentrations of arsenic, chromium, and nickel
in sewage sludge for active sewage sludge disposal
units with boundaries that are 150 meters or more
from the surface disposal site's property line.
• A certification statement, as worded in Figure 11-2.
• A description of how certain pathogen and vector
attraction reduction requirements are met.
Table 11-1 outlines a summary of pathogen and vector
attraction reduction recordkeeping requirements for sur-
face disposal of sewage sludge (U.S. EPA, 1992).
11.2.4 Recordkeeping Requirements for
Surface Disposal of Domestic Septage
For sites where domestic septage is surface disposed,
the recordkeeping requirements are dependent on the
manner in which vector attraction reduction is achieved
as follows (U.S. EPA, 1994b):
• If vector attraction reduction is achieved by adjusting
the pH of the domestic septage, the person who
placed the domestic septage on the surface disposal
site must certify to this (see Figure 11-3) and develop
a description of how vector attraction reduction was
achieved. The certification and the description must
be kept for 5 years.
OR
• If vector attraction reduction is achieved by injecting
or incorporating the domestic septage into the soil,
or by covering it with soil daily, all management prac-
tices for surface disposal of sewage sludge must be
met. Certification that all these requirements have
been met and a description of how they were met
must be developed and maintained for 5 years. (Fig-
ure 8-1 in Chapter 8 shows an example of the re-
quired certification statement.)
11.2.5 Part 258 Recordkeeping Requirements
Under Part 258, all documentation and recordkeeping
requirements are the responsibility of the owner/opera-
tor of the MSW landfill. A complete discussion of the
recordkeeping and reporting requirements for MSW
landfills regulated under Part 258 is beyond the scope
of this manual. For more information on this subject, the
reader is referred to U.S. EPA (1993a).
11.2.6 Other Recordkeeping Requirements
Other federal, state, and local agencies may require
specific records to be maintained to comply with permits
or regulations. These include:
"I certify, under penalty of law, that the pathogen requirements in [insert
§503.32(a), §503.32(bX2), §50332(b)(3), or §503.32(b)(4) when one of these
requirements h met] and the vector attraction reduction requirements in [insert
one of the vector attraction reduction requirements in §503.32(bXl) through
§503.32(b)(8) when one of these requirements is met] have/have not been met
This determination has been made under my direction and supervision in
accordance with the system designed to ensure that qualified personnel properly
gather and evaluate the information used to determine that the [pathogen
requirements and vector attraction reduction requirements if appropriate] have
been met. I am aware that there are significant penalties for false certification,
including the possibility of fine and imprisonment."
Signature
Date
Figure 11-2. Certification statement required for recordkeeping: Preparer of sewage sludge placed on surface disposal site (U.S.
200
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Table 11-1. Certification statement required for
recordkeeping: Owner/Operator of surface
disposal site (U.S. EPA, 1994b)
Required Records
Who Must Keep
Records?
Description
of How
Class A or B
Pathogen
Requirement
Was Met
Description
of How
Vector
Attraction
Reduction
Requirement
Was Met
Certification
Statement
That the
Requirement
Was Met
Sewage Sludge—Pathogen Requirements
Person preparing • •
trie sewage
sludge
Sewage Sludge—Vector Attraction Reduction Requirements
Person preparing • *
sewage sludge
that meets one
of the
treatment-related
vector attraction
reduction
requirements
(Options 1-8)
Owner/operator of • •
the surface
disposal site if a '
barrier-related
option (Options
9-11) is used to
meet the vector
attraction
reduction
requirement ?
Domestic Septige
Person who places • *"
domestic
septage on the
surface disposal
site if the
domestic
septage meets
Option 12 for
vector attraction
reduction
Owner/operator of • •
the surface
disposal site if a
barrier-related
option (Options
9-11) is used to
meet the vector
attraction
reduction
requirement
Water Quality. As part of the monitoring program for
a discharge permit, such as from a leachate collec-
tion or treatment system.
OSHA and/or State Workplace Safety Requirements.
Information on jobsite safety and safety training and
education. This includes maintenance of a file of Ma-
terial Safety Data Sheets for all potentially hazardous
materials used by employees.
11.3 Cost and Activity Recordkeeping
11.3.1 General
It i& important for the surface disposal site manager to
maintain an efficient recordkeeping system. Records
must be maintained for administrative use (i.e., payroll,
personnel management, purchasing, etc.), manage-
ment decisions (planning and cost control), as well as
compliance with regulatory requirements (see Section
11.2). The specific records to be maintained will depend
on factors such as the type and size of the site, the
management structure (privately owned, municipal facil-
ity, etc.), the source of operating funds (userfees, sewer
fees, general revenue, etc.), and the requirements of the
regulatory agencies.
11.3.2 Cost Recordkeeping
A primary concern of a surface disposal site owner/op-
erator is to control costs. Maintaining accurate records
of income and expenditures allows the site manager to
determine unit costs for the site, maintain cost control,
and predict future financial requirements. Costs may be
computed on the basis of time, or units of sludge, such
as wet tons, dry tons, or cubic yards. Based on this
information, the income requirements for the site can be
determined.
Effective cost control requires timely recognition of ex-
cessive costs and identification of the reason for such
cost overruns. The increasing costs and complexities of
sludge disposal operations require the use of more so-
phisticated cost control tools than have been used in
the past. Use of cost accounting systems at surface
disposal sites are recommended for management to
control costs.
Because user fees are generally not charged at surface
disposal sites (reducing the need for accountability) and
surface disposal sites are not separate enterprises, but
merely a secondary facet of a larger operation, cost
records at many such sites are either nonexistent or
poorly maintained.
The installation of a cost accounting system has several
benefits, as listed below:
• The system facilitates orderly and efficient accumu-
lation and transmission of relevant data. Much of the
recommended data either should be or is already
collected. Hence, the added cost of installing the
system is minimal.
• The data can be grouped in standard accounting
classifications. This simplifies interpretation of results
and comparison with data from previous years or
other operations. It also supports analysis of relative
performance and operational changes.
201
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An individual placing domestic septage on a surface disposal site must maintain
the following certification statement for 5 years:
"I certify, under penalty of law, that the vector attraction reduction
requirements in §503.33(b)(12) have/have not been met. This determination
has been made under my direction and supervision in accordance with the
system designed to ensure that qualified personnel properly gather and
evaluate the information used to determine that the vector attraction
requirements have been met I am aware that there are significant penalties
for false certification, including the possibility of fine and imprisonment." '
The owner or operator of the surface disposal site must maintain the following
certification statement for 5 years:
"I certify, under penally of law, that the management practices in §503.24
and the vector attraction reduction requirements in [insert §503.33(b)(9)
through §503.33(b)(l 1) when one of those requirements is met] have/have
not been met. This determination has been made under my direction and
supervision in accordance with the system designed to ensure that qualified
personnel properly gather and evaluate the information used Co determine
that the management practices [and the vector attraction requirements, if
appropriate] have been met. I am aware that there are significant penalties
for false certification, including the possibility of fine and imprisonment"
Signature
Date
Figure 11-3. Certifications required when domestic septage is placed in a surface disposal site (U.S. EPA, 1994b).
• The system can account for all relevant costs of con-
struction and operation.
• Accumulated data from the system can be used to
identify which costs are high and the reasons for
these high costs. These data can then be used to
develop standards of performance and efficiency to
mitigate inefficient and costly operations.
• The system includes automatic provisions for ac-
countability. Cost control becomes more effective
when the individual responsible for cost increases
can be ascertained.
• Use of the collected data aids in short- and long-term
forecasting of capital and operating budgets. Future
requirements for equipment, manpower, cash, etc.,
can be accurately estimated. This, in turn, aids plan-
ning at all levels of management.
• The system can be flexible enough to meet the man-
agement requirements associated with different types
of surface disposal sites, different types of opera-
tions, and different sludge quantities and types.
11.3.3 Activity Records
The recordkeeping system should include complete re-
cords of the activity at a surface disposal site. A daily
report should be completed by the operator on site. This
information can be used by the site manager for billing
purposes, administrative use, equipment maintenance,
material purchases, and management analysis of the site.
The activity record should include such information as:
• Quantity and type of sludge received by truckload
• Cover material utilization
• Personnel and equipment hours
• Miscellaneous expenses
• Sludge placement locations
Some of this information may be available from the
treatment works, and some or all will be recorded at the
site. Figure 11-3 is a sample form that could be used to
record the quantity of sludge received from each incom-
ing truck on a single day. The daily sludge quantity can
be totaled at the bottom of the daily form and transferred
to the monthly summary included as Figure 11-4. The
monthly summary can be used to record the sludge
quantity received, as well as cover soil utilization, per-
sonnel and machine hours, and miscellaneous expenses.
11.4 Part 503 Reporting Requirements
77.4.1 General
In general, the owner/operator of a surface disposal site
will not be required to report unless specifically notified
that the site has been designated as a "Class I sludge
management facility" by the EPA Regional Administrator
or the State Director of an approved sewage sludge
management program. If a surface disposal site is des-
ignated as Class I, the types of information that will need
to be reported will be the same information as kept for
the recordkeeping requirements. Annual reports cover
information generated during the calendar year (Janu-
ary 1 through December 31). Owners/operators would
be expected to submit data collected during the course
of the year. They are not expected to resubmit the
202
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Site:
Month:
Completed By:
*
~T—
, ^ ...
'4
i
' rf™
.,, j .
A
— * -
'ifl
p*
rrn
u
TT^
-ft
TT"
,<)
Sludge
"Jd—
p'J
M
-73T-
M
?r
~nr
TgraU
Covar material
(•mam
Man
hn.
Machine
hn.
TIU
Dawn
Exat-x
i r/«
Sir.
hn.
1 ton • 0.907 Hg
Figure 11-4. Monthly activity form.
one-time documentation on siting and design condi-
tions. Annual reports should be submitted to the EPA
Regional Water Compliance Branch Chief. The address
for each Branch Chief is provided on the inside of the
back cover of this document. The map on the inside of
the front cover shows the EPA Region in which each
State is located.
In addition, owners/operators who are also preparers of
sewage sludge are required to submit an annual report
if they are a Class I sludge management facility or if they
are publicly owned treatment works (POTWs) with a
design flow rate equal to or greater than 1 million gallons
per day or POTWs that serve 10,000 people or more.
Class I sludge management facilities are defined as
POTWs required to have a pretreatment program under
40 CFR 403.8(a), including any POTW located in a State
that has elected to assume local pretreatment program
responsibilities under 40 CFR 403.10(e). The EPA Re-
gional Administrator has the authority to designate ad-
ditional facilities, including surface disposal sites as
Class I. Preparers include persons who generate sew-
•age sludge and persons who derive a material from
sewage sludge. Any owner/operator of a surface dis-
posal site who is also a preparer should refer to U.S.
EPA (1993b) for a full discussion of the preparers'
responsibilities. •
11.4.2 Reporting Requirements in the Event
of Closure
Owner/operators of surface disposal sites that have ac-
tive sewage sludge units that will close are required to
submit a written closure and post-closure plan to the
permitting authority 180 days prior to the closure date.
The plan must include the following elements:
• Discussion of how the leachate collection system will
be operated and maintained for 3 years after the
sewage sludge unit closes (for units with liners and
leachate collection systems, only).
• -Description of the system used to continuously moni-
tor, for 3 years after the unit closes, methane gas in
the air in any structures within the surface disposal
site and in the air at the property line of the surface
disposal site (for units with covers only).
203
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• Discussion of how public access to the surface dis-
posal site will be restricted for 3 years after closure of
the last sewage sludge unit in the surface disposal site.
In addition, the owner of the surface disposal site must
provide written notification to the subsequent owner of
the site that sewage sludge was placed on the land. The
notification should include:
• Map of the surface disposal site clearly showing the
locations of sewage sludge units and their dimensions.
• Amount and quality of sewage sludge placed on
each unit.
• Results of methane gas monitoring, if conducted.
• Type of liner and leachate collection system installed,
if appropriate, and the volume and characteristics of
leachate collected.
• Copy of the written closure and post-closure plan.
• Warnings, as appropriate, that for three years after
closure air must be monitored for methane gas if a
final cover is placed on any closed sewage sludge
unit; that leachate has to be collected and disposed
of properly if a closed unit has a liner and leachate
collection system; and, that public access has to be
restricted.
11.5 Management Organization
11.5.1 General
Surface disposal sites are managed by either public or
private entities. Public management may be by munici-
pal or county government, or by a quasi-governmental
organization such as a sanitary district.
11.5.2 Municipal Operation
Most surface disposal sites operating today are munici-
pal operations. In these cases, operation and manage-
ment is usually by either the sewer department or the
department of public works. Sewer departments often
manage the disposal site because it is used to dispose
of the sludge generated at the department's treatment
works. Also, because sludge disposal is part of the
overall wastewater treatment process, it is usually sup-
ported by the same budget and/or fee structure. Dis-
posal sites are often located adjacent to the treatment
works on land owned by the municipality.
Management by public works departments is becom-
ing increasingly common. This arrangement is usually
more appropriate for management of larger sites or
those located some distance from the treatment plant.
Operation of these sites requires construction-type ac-
tivities, making the management requirements more
suited to the experience and resources of a public works
department.
11.5.3 County Operation
Management of surface disposal sites by county gov-
ernments is less prevalent than that by municipal gov-
ernments. As with municipal governments, county-
operated sites are often managed by either a sewer
department or public works department. County sites,
however, typically serve larger populations and geo-
graphic areas. In these cases the economies of scale
and greater availability of land for the site favor county-
operated sites.
The choice between municipal or county operation is
usually determined by which government operates the
sewer department. This should not be the only determin-
ing factor, however, as county-wide management of sludge
disposal can be a favorable option even when wastewa-
ter treatment is conducted by individual municipalities.
11.5.4 Sanitary District Operation
Sanitary districts are usually responsible for managing
surface disposal sites when no alternate authority is
available. Financing for sites managed by sanitary dis-
tricts is often easier to secure because they usually have
the power to levy special taxes or user fees. Because
these districts generally service greater populations and
may serve several municipal jurisdictions, they often.are
better financed and equipped to operate surface dis-
posal sites due to the economies of scale.
11.5.5 Private Operation
Next to municipal operations, private management is the
most prevalent type of site management. Sites may be
operated under contract, franchise, or permit arrange-
ment. In contract operations, the government agency
contracts with the private operator to dispose of its
sludge for a fixed lump sum fee, or a unit charge (per
ton, cubic yard, ortruckload). If a unit charge is the basis
of the contractual arrangement, the government agency
usually guarantees a specified minimum dollar amount
to the contractor. Franchises typically grant the operator
permission to dispose of sludge from specified areas
and to charge fees that are usually regulated. Permits
allow the operator to accept sludge for disposal without
regard to source.
Private operations are advantageous for government
agencies with limited capital available for construction
and initial operation of a disposal site. Private operators
are often able to operate at a lower cost than govern-
ment facilities. Precautions should be taken, however,
to ensure that private operators provide adequate envi-
ronmental safeguards and comply with all regulations.
For this reason, contract arrangements are usually the
204
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most advantageous option for the government because
operating and performance standards can be written
into the contract.
11.6 Staffing and Personnel
11.6.1 General
Staffing requirements for a surface disposal site de-
pends on the size and type of the site. Estimates of the
size of the staff required should be developed during the
design process and then refined into a formal staffing
plan for the site. The staffing plan will provide informa-
tion for estimating operating costs and serve as a guide
for personnel hiring and management.
11.6.2 Personnel Descriptions
• Equipment operator. At many surface disposal sites,
equipment operators are the only onsite personnel
required. Tasks performed are mostly those of equip-
ment operation. Other tasks, however, may include
routine equipment maintenance and directing sludge
Unloading operations. A sample equipment inspection
form to be completed daily by equipment operators
is included as Figure 11-5,
Truck
I dent.
Totals
Time*
Sludge
Source?
Type*
Sludge
Weight
or •
Volume
:
i
1
Instructions: To be completed for each truck, each
time it makes a delivery.
* Only record time at 15-rainute intervals
t Sources: Code for Contributing Treatment Plant
+ Types: G'= grit; DI » digested; CT =• chemically
treated
Figure 11-5. Dally waste receipt form.
• Superintendent/Foreman/Supervisor. This position
involves overseeing all aspects of the disposal site
operation, including maintaining daily records of op-
eration, personnel supervision, and managing the
daily activities at the site. Depending on the size of
the site, this person may serve other functions such
as equipment operator.
• Mechanic. Major equipment maintenance and repair
should be performed by qualified mechanics. Me-
chanics or maintenance teams, however, are usually
not needed full-time on the site. They usually come
to the site on a regular schedule or as needed.
• Laborer. Larger surface disposal sites may need one
or more persons to maintain control systems (e.g.,
leachate collection and treatment odor control, truck
washing station, mud and dust control, etc.). The
duties may also include maintaining the fencing and
access roads.
In addition to the above listed personnel on site, offsite
support personnel may also be required for efficient
operation of a surface disposal site. Such personnel
may include any of the following:
• Clerical. Clerical personnel maintain the records for
the site, process personnel actions, and perform daily
administrative duties.
• Engineering consultant. A technical consultant should
be available to advise the site manager on the design
and operational aspects of the site and its activities.
The consultant would assist in identifying and solving
any technical problems that may arise, assisting with
regulatory compliance issues, and planning and im-
plementing changes to the site, such as expansion
or closure.
• Management consultant. A management consultant
can provide assistance on administrative and finan-
cial issues for the site manager. The consultant can
provide advice on the administration of the site, and
on financing options for obtaining funds for capital
and operating expenses.
• Legal consultant. A legal consultant can provide legal
services for, issues such as permitting and regulatory
compliance, public hearings, contract review, and
planning for activities such as post-closure use.
11.6.3 Training and Safety
It is important to employ well-trained personnel. Quali-
fied personnel can be the difference between a well-
organized, efficient operation and a poor operation. New
employees should not only learn the tasks required for
their positions, but also understand the purposes and
importance of the overall disposal operation. Except for
the larger operations, comprehensive training programs
are not likely to be designed or conducted by the site
205
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management. Training programs have been developed
by the U.S. Environmental Protection Agency, profes-
sional organizations such as the American Public Works
Association, and some educational associations. Be-
cause many of the procedures employed at municipal
solid waste landfills are similar or identical to those
employed at some types of sludge surface disposal
sites, such programs may also be useful. Programs may
consist of guideline information on training activities to
be conducted by the employer, or classes conducted by
these agencies. Equipment manufacturers are another
source of information on training procedures.
Managers of surface disposal sites have an obligation
to maintain safe and secure working conditions for all
personnel. It is important that safety rules are written,
published, distributed to all employees, and enforced. A
safety training program, covering all aspects of site
safety and proper equipment operation, as required by
OSHA or State safety programs, should be conducted
on a regular basis.
For safety reasons, it is desirable to have two or more
persons working on site at any time. This can easily be
accomplished at large surface disposal sites where
more than one person is needed for daily operation. On
small sites requiring only one operator, a second person
should visit the site daily or the single operator should
phone or check in at the end of the shift.
At a large site,, a foreman and subordinate supervisors
may be required. A multi-shift operation will require a
supervisor for each shift as well as an overall manager.
No matter what the size of the operation, one person
should be responsible for safety on site, and be familiar
with OSHA and State regulations and procedures.
A safety checklist prepared by the National Solid Waste
Management association is included as Figure 11-6.
Site:
Machine:
Date:
Completed By:
Hour Meter Reading:
UfOK SUITING CHICK
WATEK Q
INC. OIL D
IIANS. Q
FUEL
WATEK ADDED F«ONT Q
ENG.OIl ADDED FIONT D
'HANS.on AOOIO now n
nronAuuCOiiAOOBO rn
FIONT U
AFTE> STAKING LEVEL MA.;HINI AND CHICK
ENCINI OIL Q __^___
TUNS. Q
WATE» ADDED MM Q
~ ENO.OIl ADDED MAI Q
HYOUIAJC OH Q
ANV LEAKS
UAKES
STEEIING
TIANSMISSION
MESiLKt
GAUGES
SHIFTING
ENGINE
TEMF.
OIL FtESSUDE
WATEH TEMF.
UNOEHCAUIAGE
HACK ADJUST.
IOILE* WEA*
TIDES
IIADE
CUTTING EDGES
TIUNNIONS
NYDIAUtlCS
FUMF
JACKS
OTHCt
All CLEANIIS
UD. CLEAN
HACK CLEAN
TIDES FUE OF MUD
a
a
a
Cl
C)
G
a
a
C!
Q
C)
C)
Cl
Q
a
o
D
a
D
C
a
n
Q
D
D
a
11.7 References
1
U.S. EPA. 1994a. Surface disposal of sewage sludge: A guide for
owners/operators of surface disposal facilities on the monitoring,
recordkeeping, and reporting requirements of the federal stand-
ards for the use or disposal of sewage sludge, 40 CFR Part 503.
EPA/831/B-93/002C. Washington, DC (May).
2. U.S. EPA. 1994b. A plain English guide to the EPA 503 biosolids
rule, EPA/B32/R-93/003.
3. U.S. EPA. 1993a. Solid waste disposal facility criteria, technical
manual. EPA/530/R-93/017 (NTIS PB94-100-450). Washington,
DC (November).
Figure 11-6. Equipment inspection form.
4. U.S. EPA. 1993b. Preparing sewage sludge for land application or
surface disposal—A guide for preparers of sewage sludge on the
monitoring, recordkeeping, and reporting requirements of the fed-
eral standards for the use or disposal of sewage sludge, 40 CFR
Part 503. EPA/831/B-93/002a. Washington, DC.
5. U.S. EPA. 1992. Environmental regulations and technology: Con-
trol of pathogens and vector attraction in sewage sludge (including
domestic septage) under 40 CFR Part 503. EPA/625/R-92/013.
Cincinnati, OH (December).
206
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BUILDING EXITS (OSHA 1950.35 - 1910.37)
1.
2.
3.
4.
5.
6.
i.ombustt
1
r~
?.
3.
9.
10.
11.
12.
13.
U.
15.
16.
17.
13.
~~1'9'.
20.
21.
22.
23.
24.
25.
26.-
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
33.
39.
40".
41.
•42.
43.
44.
45.
46.
47.
48.
49.
Jo.
51.
57
Doors swing with exit travel
Marked with lighted signs
Not locked so that rhey may be used from the inside ot oil times :
Keeo fre* of obstructions
Non-exit doors which coo be mistoken os on axil at on exit or* morked "No Exit*
Singl« exits or* allowed for rooms containing Its! than 25 people
ble. Oxidizing, ond Flammable Agents, When Using (OSHA 191051 -I9JO. 1 16J
Electrical instollarion and static electricity or* controlled or maintained
Heating appliances at* controlled or maintained in a safe manner
"Hot" work (welding) controlled or maintained in a safe manner
At least one 20 pound Class B fire extinguisher it within 25 feet of a storage area
ICC approved maKsl drums ore used for storage from 5-60 gallons
Not more than required for on* day or shift stored outside storage cabinet
dC)MPflE"SSE& AND LlCtUlftr-O GASES (OSHA 1910.101-1910.116)
Charged ond empty cylinders are separated
Cylinders are grouped by typ* and stored in vertical positions
Cylinders are not stored near other combustible material
Cylinders ore supported so that they eonnof b* tipped over
Cylinder caps are in place on all cylinder) which are not in use
Oxygen cylinders are not stored within 20 feel of other types of gases
DRAINAGE
Drains or* vented to prevent collection of combustible gases
Grease ond oil prevented from entering public 'sewog* systems
ELECTRICAL EQUIPMENT (OsnA I9l0.30o-l$l0.309l
All outlet ond junction boxes are properly covered
All portable electrical tools and appliances are properly grounded
Records maintained for inspection or portable electrical tools ond appliances
Electrical cabinet doors with, exposed conductor! of 50 volts or mor* or* securely fastened
Enclosures around high voltage electrical equipment are marked
Frayed cords, cobles, ond loose wires regularly removed From service
Switch boxes aro identified as to equipment they control
EMERGENCY LIGHTING
Exits and necessary ways to exits are illuminated
Exit signs or* illuminated to at least 5 foot candles
flRE EXTINGUISHER EQUIPMENT (OSHA 1910.157)
Extinguishers are inspected monthly for physical damage
Inspection records are kept indicating inspector
Maintenance performed yearly; hydrotested every 5 years, if required
-Inspection togl marked by month and year ,
Extinguishers conspicuously installed and properly marked for use by type of fir* (A.B.CarD)
The top of portable extinguishers (less than 40 Ibs) mounted no mor* than 5' above the floor
The top of portable extinguishers (40 Ibs or more) mounted no more than 3-1/2' obov* fh* floor
FIRST Alb (OSHA 1916.151)
An approved first aid kit is available
Emergency numbers of company-approved doctors ond hospitals posted in appropriate locations
Trained personnel available
HAND AN& PORTABLE fOOlS (OSHA l9IO.44i-t7IO.247)
Alt useoble tools Hove guards properly installed
All portable electrical tools are tested monthly for ground
Records kept of inspection (item 4f)
All tools in safe operating condition are free from worn or defective parts
Jacks and hoists are legibly marked with the load rating
hOUSEtfEEPlNG
Material on wallvshilves stored m a safe and orderly manner
Facility is in a clean, orderly, ond sanitary condition
Hoses, welding leads, drop lights, *tc. or* rolled ond property stored
Permanent aisles ond passageways ore fr»* of obstructions
Permanent aisles and passageways are permanently marked
ILLUMINATION
Sufficient quantity (20 foot candles or greater)
Uniform distribution
W.ll rfirMtod
INDUSTRIAL SANITATION (OSHA 1910. Uli
i
f—
53.
54.
55.
56.
57.
Clean, available drinking fountains '
Hot water available
Individual towels and drinking cups available
Toilet facilities or* within 200 fee*t of working area for each sex
INDUSTRIAL TRUCK: FORKLIFT (OSHA 1910.178)
58.
59.
60.
61.
62.
63.
64.
65.
66.
Brakes in good' operating condition
Guard behind fork is in place (to guard from load falling to the rear)
Load capacity of truck marked
No one except operator permitted to ride
No one stands or walks under raised Forks
Overhead guard to protect against falling objects
Recharging/refueling don* in o "No Smoking" isolated area
Training program far operators
Warning devices (horn) working
LADDERS (OSHA 1910.25-1910.28)
67.
69.
69.
70.
71.
Anti-slip safety steps used on portable ladders
Caution exercised when metal ladders used in electric current areas
Cautiah exercised when metal ladders used with portable *l*etric tools
Ladders inspected monthly with inspection records kept
Straight ladders properly secured
Figure 11-7. Safety checklist.
207
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(QihA I9tu.
72. Bulk storage (126 to 500 gollons) ot least 10 feet from building
73. Bulk stores* (SOI to 2,000 gal lorn) at least 25 feet from building
74. Bulk storage (231 to 2,000 gallant) at !»ait three feet separation between tanks
75. Containers labeled by size (in pounds or gallons)
76. Containers labeled with pressure in "gouge psi"
77. Containers labeled by type of L.P.G.
78. Containers havo safely relief and shut-off valves
79. Containers stored away from exits
80. Distance between L.P.G. container! and flammable liquid container* it 20 feel
81. No containers art stacked on* above the other
82. Containers ore stored in o "No Smoking" oreo
GUARDING J65HA 1910.21l-l9l0.2Hl
S3. Abrasive wheels in accordance with type of work "
34. Abrasive wheels in good condition
85, Abrasive wheels labeled and in accordance with rpm ratings
86. Abrasive wheels uniform in diameters
67. Air nozzles used for cleaning meet 30 osi limit
88. All rotating, cutting shearing, screw and worm, blending, and forming motions guarded
89. Safety precautions understood and used by shop employees
90- Steady resrs on grinders meet 1/8" adjustment to wheel requirement
PER
SONAL PROTECTIVE iQulfrMfNT (05HA I9lf).»i, I»IO. '132-1910707" _
All protective equipment maintained in safe working condition
Car protection worn when noise dSA greater than 90 for 8 hours
Ear protection worn when noise dBA greater than 95 for 4 hours
Ear orotection worn when noise dBA greater rhon 100 for 2 hours
Ear protection warn when noise dBA greater thon 105 far I hour
Ear protection worn when noise dBA greater thon 110 for 1/3! hour
Ear protection worn when noise diA greater than 1 15 for 1/4 hour
Eye end face protection provided where reasonable probability of Injury exists
Respiratory protective equipment worn whan air is contaminated (dust, gases, etc.)
Safety shoes, coos, gloves worn when necessary
»r.i..E -A.I... i^iA i.. . — . A' ±
92.
93.
94.
95.
96.
97.,
98.
99.
1JC.
TCSHA 1910.21-1910.24)
101. Angle of rise is between 30 to 50 degrees
102. Fixed stairs hove at least a 22" width
103. Fixed stairs have at least a 1000 Ibs. load strength
104. Non-ilio treads are present
105. Stoir railings are 30-34" from top roil surface to forward edgn of step
'Co. Stairways less thon 44" wide Tooth sides enclosed) hove at least one handrail
1ST. Stairways less thon 44" wfde 'one side open) have at least one stair raiting on open side
108. Stairways over 44" wide (borh sides open) have two railings
109. Srcndaro ratlings are 42" nominally from top surface of floor
HO. Wood railing posts at leait 2" x 4" slock spaced not to exceed 6 feet
111. Pipe railings ond posts ot least 1-1/2" nominal diameter
1)2. Pipe roiling posts spaced not to exceed 3 feet
113. Structural steel ratlings =nc Dosrs at least 2" x 2"
114. Structural steel roiling posts spaced not to exceed B feet
VENTILATION (OSHA 1910.94)
MS. Exhaust system for removal of toxic fumes ond dust from work oreo
WAUING, WORKING SURFACES tQSHA J9(6.Jl-.
Aijiet ond passageways unoeirructed
Perfnonent walkways marked
Floor hole openings guarded and marked
Floor surfaces in good condition ond uncluttered
TToT
117.
ltd.
119.
WELDING, CUTTING, HeATING OR BRAZING tOSHA 1910.251-1910.254V
120.
121.
122.
123.
124.
125.
Aceryler* not us«d ar prauor*. greater rhan 15 pug
Eye protection worn, where required* by exfenf of hazard
During welding operations, oaoreciobfe combustibles more than 35 feet away
During welding operations, floor iwept clean of combustibles wtrhln 35 f«ef
Fire watch practiced/ where necessary
Frame of alectn'c welding rr^hine grounded
fne grounded
SAK.V REQ
HEAVY EQUIPMENT
Each piece of equfpn>»wif has roll-over protection (i»e Sech'on X-"Rotl Ovei' Protecrio
Schedule**)
Each p-ece of equipment hoi Fire extinguisher (20 Ibs. ABC Minimum)
Alt heavy equipment is equipped with backup alarm
Alt machines operating at night equipped with headlights
Seat belt* org on all equipment with roll-over protection
127.
12S.
129.
130.
MEDICAl AND FJUST AID
132.
Medical oersonnel available tor advice ond consultation
Suitable oloce to render firsr aid
133. Adjacent road (City, Store, etc.) is cleor of debris and mud
134. When possible, warning sign or light, "TRUCK ENTRANCE"
133. Landfill rood crowned and proper drainage
134. Landfill rood kept prooerly cleaned of debris
137. Landfill rood has proper oust control by means of a water wagon or water truck
138. Traffic Control Signs (Landfill) - Stop sign (for vehicle leaving landfill before
entering public street)
139. Traffic Control Signs (Landfill) - Speed limit signs
140. Traffic Control Signs (Landfill) - No parking signs
LANDFILL Silt
|4I. All underground cobles, Ptpes, etc., are cleorlv marked ono identified
142. Utility wires are of sufficient height to allow clearance for all equipment using
landfill
143. Security fences ond landfill site is kept free as possible of blowing paper aind debrn)
Figure 11-7. Safety checklist (continued).
208
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Chapter 12
Closure and Post-Closure Care
12.1 General
Closure is the procedure through which a surface dis-
posal site is closed after sewage sludge is no longer
placed on the land. Issues to be addressed during clo-
sure include:
• Covering the sludge to control odors and vectors
(insects, animals).
• Proper leachate management to prevent contamina-
tion of ground water or surface water.
• Prevention of methane gas accumulation.
• Maintaining a stable and secure site throughout the
post-closure period.
• Selection of and preparation for the final end use of
the site.
12.2 Regulatory Requirements
12.2.1 Part 503
The requirements for closure of a surface disposal site
regulated under Part 503 are specified in Section
503.22. These requirements pertain to closing active
sewage sludge units in a surface disposal site. Under
these requirements:
• Closure is required if an active sewage sludge unit
is located in certain types of areas. If an active sew-
age sludge unit is located within 60 meters of a fault,
in an unstable area, or in a wetland, the unit must
close by March 22, 1994. There are two exceptions
to this requirement: (1) if the permitting authority has
indicated that the location of a specific unit within 60
meters of a fault is acceptable, or (2) if a permit was
issued under the Clean Water Act that allows the unit
to be located in a wetland (U.S. EPA, 1994).
• If an active sewage sludge unit closes, the permitting
authority must be notified. If an active sewage sludge
unit is about to be closed, the owner/operator of
the unit must provide the permitting authority with a
written plan that describes closure and post-closure
activities. At a minimum, the following information
must be included in the plan: (1) how the leachate
collection system will be operated and maintained for
3 years after closure (if the unit has such a system);
(2) a description of the system used to monitor air for
methane gas for 3 years after closure (if the active
sewage sludge units are covered); and (3) how public
access will be restricted for 3 years after closure. This
information must be provided to the permitting author-
ity 180 days before the unit closes (U.S. EPA, 1994).
The permitting authority may determine that the closure
plan must include provisions for methane gas monitor-
ing or leachate collection for more than 3 years. For
example, if the sewage sludge placed in the active
sewage sludge unit was not stabilized, it may be neces-
sary to monitor air for methane gas and restrict access
for a longer period to protect public health. Also, in areas
of high rainfall, the permitting authority may determine
it necessary to collect leachate for a longer period
to ensure that the integrity of the liner is maintained
(U.S. EPA, 1994).
Under the general requirements of Part 503:
• Any subsequent landowner must be notified that the
land was a surface disposal site. The owner of a
surface disposal site must provide the subsequent
owner with written notification that sewage sludge
were placed on the land (U.S. EPA, 1994).
The notification required for the subsequent owner of a
surface disposal site will vary depending on when the
land was sold and the provisions of the closure plan. For
instance, if a surface disposal site was covered, had a
liner, and was sold 1 year after closure, the notification
would inform the next owner that the property was used
to dispose of sewage sludge and that the new owner
must operate the leachate collection system, monitor air
for methane gas, and restrict public access for an addi-
tional 2 years (U.S. EPA, 1994).
12.2.2 Part 258
The requirements for closure and post-closure care of
a municipal solid waste (MSW) landfill are regulated
under Section 258.60 of Part 258. This regulation also
requires the owner/operator of the MSW landfill to pre-
pare a written closure plan. A complete discussion of the
209
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closure requirements under the Part 258 regulation is
beyond the scope of this manual. The reader is referred
to U.S. EPA (1993) for additional information on these
requirements.
12.3 Closure
12.3.1 Closure Plan
The closure plan is the document that specifies the
criteria and procedures to be followed during closure
and the post-closure period. The closure plan should be
developed during the site selection and design process,
because issues that occur at these stages can ultimately
impact closure and the end use of the site. Also, by
integrating the final site plans into the preliminary de-
sign, the ultimate value and cost of developing the final
site can be enhanced.
The closure plan should be reviewed and updated as
necessary during the operational life of the facility. The
objectives of a closure plan include:
• Designating the design criteria and operational pro-
cedures for closure.
• Identifying operational and maintenance require-
ments of the post-closure site.
The contents of a closure plan varies depending on a
number of factors, such as the type of surface disposal
site, the regulations controlling the site (i.e., Part 503 or
Part 258), specific features of the site, the concerns of
the public, and the requirements of the regulating
authority. The contents of a closure plan may include:
• Cover system design
• Vegetative cover design
• Stormwater management controls
• Inspection and maintenance procedures
• Leachate management controls
• Methane gas management controls
• Other environmental controls
• Plans for site access restriction and security
• Management and recordkeeping requirements
• Financial requirements
Figure 12-1 outlines a sample closure and postclosure
plan for an active sewage sludge unit (U.S. EPA, 1994).
12.3.2 Cover for Monofills or MSW Landfills
The design criteria for landfill closure focus on two cen-
tral themes: (1) the need to establish low-maintenance
cover systems and (2) the need to design a final cover
that minimizes the infiltration of precipitation into the
waste. Landfill closure technology, design, and mainte-
nance procedures continue to evolve as new geosyn-
thetic materials become available, as performance
requirements become more specific, and as perform-
ance history becomes available for the relatively small
number of landfills that have been closed using current
procedures and materials. Critical technical issues that
must be faced by the designer include (U.S. EPA, 1993):
i1 ',,",'",' ,1 '
• Degree and rate of postclosure settlement and
stresses imposed on soil liner components.
• Long-term durability and survivability of cover system.
• Long-term waste decomposition and management of
landfill leachate and gases.,
• Environmental performance of the combined bottom
liner and final cover system.
Much information has been developed on final cover
systems for landfills. The reader is referred to the refer-
ence U.S. EPA (1988) and U.S. EPA (1993) for further
information on landfill cover systems.
12.3.2.1 General
The cover system is a physical barrier placed over the
sewage sludge unit consisting of layers of soil and
gee-membrane material that isolate the sludge. The de-
sign criteria for a final cover system should be selected
to (U.S. EPA, 1993):
• Minimize infiltration of precipitation into the sludge
• Promote good surface drainage
• Resist erosion
• Restrict gas migration and/or enhance recovery
• Isolate the sludge from vectors
• Improve aesthetics
• Minimize long-term maintenance
Reduction of infiltration in a well-designed final cover
system is achieved through good surface drainage
"and runoff with minimal erosion, transpiration of water
by plants in the vegetative cover and root zone, and
restriction of percolation through earthen material
(U.S. EPA, 1993).
Each element of a cover system consists of a>layer of
soil or other material selected to meet the requirements
of a specific design criteria. Each element should be
selected and designed based on the requirements of the
specific site and the applicable regulations. The ele-
ments of a cover system are the erosion layer, the
drainage layer, the infiltration layer, and the gas venting
layer. Figure 7-24 in Chapter 7 illustrates the minimum
requirements for the final cover system (U.S. EPA, 1993).
210
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Owner/Operator Name:
Mailing Address:
Telephone Number:
Address of Active Sewage
Sludge Unit Location:
I. ACTIVE SEWAGE SLUDGE UNIT CONDITIONS
A. General information
1. Size of active sewage sludge unit (hectares or acres)
2. Description of liner, if applicable
3. Description of leachate collection system, if applicable
4. Copy of NPDES permit if there are discharges to U.S. waters
B. Schedule of final closure (milestone chart)
1. Final date of sewage sludge accepted
2. Date all onsite disposal completed
3. Date final cover completed
4. Final date vegetation planted or other material placed
5. Final date closure completed
6. Total time required to close the site
H. DISPOSING OF SEWAGE SLUDGE
A. Total volume of sewage sludge to be disposed of on the active sewage sludge
unit (m3 or yd3)
B. Description of procedures for disposing of sewage sludge
1. Size of surface disposal site, number of active sewage sludge units, and
size of units necessary for disposing of sewage sludge (include site map
of disposal area)
2. Design and construction of active sewage sludge units
Figure 12-1. Outline of sample closure and post-closure plan (U.S. EPA, 1994).
211
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COVER AND VEGETATION
A. Final cover, if applicable
1. Total area to be covered (m2 or yd2)
2. Characteristics of final cover
a. Type(s) of material(s)
b. Depth of material(s)
c. Total amount of material(s) required
3. Final cover design
a. Slope of cover
b. Length of run of slope
c. Type of drainage and diversion structures
B. Vegetation (if vegetation is to be planted)
1. Total area requiring vegetation (hectares or acres)
2. Name or type of vegetation (e.g., rye grass)
C. Erosion Control (if vegetation is not to be planted)
1. Procedures and materials for controlling cover erosion
2. Justification for procedures and materials used
IV. GROUND-WATER MONITORING (if applicable)
A. Analyses required
I. Number of ground-water samples to be collected
2. Ground-water monitoring schedule (e.g., quarterly, semi-annually)
3. Details of ground-water monitoring program
B. Maintenance of ground-water monitoring equipment
V. COLLECTION, REMOVAL, AND TREATMENT OF LEACHATE
A. Description of leachate collection system (i.e.-, pumping and collecting
procedures)
1. Description of the leachate sampling and analysis plan
2. Estimated volume of leachate collected per month
Figure 12-1. Outline of sample closure and post-closure plan (continued).
212
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B. Description of leachate treatment process, if on-site
a. Design objectives
b. Materials and equipment required
C. Disposal of leachate
1. If discharged to surface waters, include copy of NPDES permit
2. If hauled offsite, provide final destination
D. Maintenance of equipment
1. Repairs and replacements required
2. Regular maintenance required over the duration of closure and post-
closure periods
VI. METHANE MONITORING (if applicable)
A. Monitoring requirements
1. Monitoring locations
2. Types of samples
3. Number of samples
4. Analytical methods used
5. Frequency of analyses
B. Maintenance of monitoring equipment
C. Planned responses to exceedances of limits
VH. MAINTENANCE ACTIVITIES
A. Surface disposal site inspections
1. List all structures, areas, and monitoring systems to be inspected
2. Frequency of inspections for each
B. Planned responses to probable occurrences (including those listed below)
1. Loss of containment integrity
2. Severe storm erosion
3. Drainage failure
Figure 12-1. Outline of sample closure and post-closure plan (continued).
213
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C. Maintenance of cover and/or vegetation
1. Cover maintenance activities and schedule
2. Mowing schedule
3. Reseeding and mulching schedule
4. Soil replacement
a. Labor requirements
b. Soil requirements
5. Fertilizing schedule
6. Sprinkling schedule
7. Rodent and insect control program
D. Control of erosion
1. Maintenance program for drainage and diversion system
2. Activities required to repair expected erosive damage
3. Replacement cover soil
a. Amount to be stored onsite during the post-closure period
b. Specification of alternative sources of cover soil, if applicable (i.e.,
offsite purchase agreement or onsite excavation)
INSTALLATION OR MAINTENANCE OF THE FENCE
A. If a fence already exists, describe required maintenance at closure to ensure it
is in good condition
B. If fence is to be installed, specify:
1 . Area to be enclosed
2. Type of materials used,
3. Dimensions of fence
C. Security and public access practices planned for the post-closure period
1. Description of security system
2. Maintenance schedule
IX. CLOSURE SCHEDULE
A. Schedule for closure procedures
B. Schedule of periodic inspections
Figure 12-1. Outline of sample closure and post-closure plan (continued).
214
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12.3.2.2 The Infiltration Layer
The infiltration layer is a low permeability layer consist-
ing of a low permeability soil and/or a geomembrane.
The infiltration layer must be at least 18 inches thick and
composed of earthen material that has a hydraulic con-
ductivity (K) less than or equal to the hydraulic conduc-
tivity of any bottom liner system or natural subsoils (U.S.
EPA, 1993). The permeability of the infiltration layer
should be less than or equal to the permeability of any
liner system or natural soils present to prevent a "bath-
tub effect." Figure 12-2 presents an example of a final
cover with a hydraulic conductivity equal to the hydraulic
conductivity of the bottom liner system.
In no case can the final cover have a hydraulic conduc-
tivity greater than 1 x 10"5 cm/sec regardless of the
permeability of underlying liners or natural subsoils
(U.S. EPA, 1993). If a synthetic membrane is in the
bottom liner, there must be a flexible membrane liner
(FML) in the final cover to achieve a permeability that is
less than or equal to the permeability of the bottom liner.
Currently, it is not possible to construct an earthen liner
with a permeability less than or equal to a synthetic
membrane (U.S. EPA, 1993).
For units that have a composite liner with an FML, or
naturally occurring soils with very low permeability (e.g.,
1 x 10~8 cm/sec), the Agency anticipates that the infiltra-
tion layer in the final cover will include a synthetic mem-
brane as part of the final cover (U.S. EPA, 1993). A final
cover system for a landfill unit with an FML combined
with a soil liner and leachate collection system is pre-
sented in Figure 12-3a. Figure 12-3b shows a final cover
system for a landfill that has both a double FML arid
double leachate collection system.
The soil material used for the infiltration layer should be
free of rocks* clods, debris, cobbles, rubbish and roots
that may increase the hydraulic conductivity by creating
Erosion Layer
Min.6"Soil
preferential flow paths. The surface of the compacted
soil should have a slope between 3 percent and 5
percent after settlement. It is critical that side slopes,
which are frequently greater than 5 percent be evaluated
for erosion potential (U.S. EPA, 1993).
The infiltration layer should be placed below the maxi-
mum depth of frost penetration to avoid freeze-thaw
effects (U.S. EPA, 1989b). Freeze-thaw effects may
cause the development of microfractures or realignment
of intersticial fines that can increase the hydraulic con-
ductivity of clays by as much as an order of magnitude.
Infiltration layers may be subject to desiccation depend-
ing on the climate and soil water retention in the erosion
layer. Fracturing and shrinking of the clay due to water
loss can increase the hydraulic conductivity of the infil-
tration layer (U.S. EPA, 1993). Information regarding the
maximum depth of frost penetration for a particular area
can be obtained from the Soil Conservation Service, local
utilities, construction companies, and local universities.
The infiltration layer is designed and constructed in a
manner similar to that used for soil liners, with the
following differences.(U.S. EPA, 1993):
» The cover is generally not subject to large overburden
loads, so the issue of compressive stresses is less
critical unless post-closure land use will exert large
loads.
• The soil cover is subject to loadings from settlement
of underlying materials. The extent of settlement an-
ticipated should be evaluated and a post-closure
maintenance plan designed to compensate for the
effects of settlement.
• Direct shear tests performed on construction materi-
als should be conducted at lower shear stresses than
those used for liner system designs.
Infiltration Layer
Min. 18" Compacted Soil (1 x 10-6
on/sec)
2FeetCompa«ed
SoU (1 x 10-6 cm/sec)
Figure 12-2. Example of final cover with hydraulic conductivity (K) < K of liner (U.S. EPA, 1993).
215
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Erosion Layer
To sustain vegetatio;
Infiltration Layer Mm. 18"
compacted soil (1 x 10-5
on/sec)
FML
2 Feet Compacted Soil
(1x10-7 cm/sec)
FML
Figure 12-3a. Example of final cover design for an MSWLF unit with an FML and leaehate collection system (U.S. EPA, 1993).
Erotion Layer
To sustain vegetation
Infiltration Layer Min. 18"
compacted soil (1 x
10-Son/sec)
FML
12" Compacted
Soil (1x10-7 on/sec)
FML
2 Feet Compacted
Soil (1x10-7 cm/sec)
Figure 12-3D. Example of final cover design for an MSWLF unit with a double FML and leaehate collection system (U.S. EPA, 1993).
Geomembranes
If a geomembrane is used as an infiltration layer, the
geomembrane should be at least 20 mils (0.5 mm) in
thickness, although some geomembrane materials may
need to be a greater thickness (e.g., a minimum thick-
ness of 60 mils is recommended for HOPE because of
the difficulties in making consistent field seams in thin-
ner material) (U.S. EPA, 1993).
12.3.2.3 The Erosion Layer
The erosion layer protects the cover system from ero-
sion due to water and wind. It also functions as the
growing medium for the vegetative cover. Selection of
the soil for the erosion layer should consider both its
ability to protect the underlying layers and to support the
vegetative cover. The erosion layer also protects the
infiltration layer from the impacts of freeze thaw cycles.
Soil erosion can reduce the performance of the surface
soil layer of a unit by impairing the vegetative growth or
causing rills that require maintenance and repair. Ex-
treme erosion may lead to the exposure of the infiltration
layer or the sludge, or may cause slope instability (U.S.
EPA, 1988). Eroded soil can clog stormwater drains
resulting in increased maintenance requirements.
Anticipated erosion due to surface water runoff for a
given design may be approximated using the USDA
Universal Soil Loss Equation (Eq. 12-1) as shown
below (U.S. EPA, 1989a). By evaluating erosion loss,
216
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the design may be optimized to reduce damage through
selection of optimum slopes, and best available soil and
plant materials, or by allowing excess soil to increase the
time between required maintenance (U.S. EPA, 1993).
, X = RKSLCP (Eq. 12-1)
where:
X = Soil loss (tons/acre/year)
R = Rainfall erosion index
K = Soil erodibility index
S = Slope gradient factor
L = Slope length factor
C = Crop management factor
P = Erosion control practice
Values for these parameters are available from the U.S.
Soil Conservation Service (SCS) technical guidance
document entitled Predicting Rainfall Erosion Losses,
Guidebook 537 (1978), available at local SCS offices
throughout the country.
Figure 12-4 can be used to find the soil loss ratio due to
the slope of the site as used in the Universal Soil Loss
Equation. Loss from wind erosion can be determined by
the following equation (U.S. EPA, 1989a):
A A
X' = I'K'C'L'V
(Eq. 12-2)
where:
X' = Annual wind erosion
I' = Field roughness factor
K' = Soil erodibility index
C' = Climate factor
L' = Field length factor
V = Vegetative cover factor
12.3.2.4 The Vegetative Cover
The vegetative cover protects the uppermost soil layer
from wind, water and mechanical erosion, and removes
soil water from the site through evapotranspiration. The
vegetative cover is also important because it improves
the appearance of the site.
In selecting plant species for the vegetative cover, the
following criteria should be considered (U.S. EPA, 1989b):
• Plants should be locally adapted perennials that are
resistant to drought and temperature extremes.
,-. 4
v\
3
2£ 1
|
I
Slope Length (Feet)
Figure 12-4. Soil erosion due to slope (U.S. EPA, 1993).
217
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• If part of a cover system, the plants should not have
root systems that will disrupt underlying drainage and
infiltration layers.
• The plants should be able to thrive in low-nutrient soil
conditions with minimum nutrient additions.
• There should be sufficient plant density to minimize
soil cover erosion.
• Plants should require little or no maintenance.
• Sufficient variety of plant species to continue to achieve
these characteristics and specifications over time.
Information on suitable species for a specific site is
available from the USDA Soil Conservation Service, the
Cooperative Extension Service, or local universities.
Typically, planting or seeding should be conducted in the
fall or early spring to permit seedlings time to become
established before winter freeze or summer drought
occurs. Fast-growing temporary cover crops such as
winter rye can provide a temporary vegetative cover
over winter until conditions for permanent plantings are
favorable (U.S. EPA, 1993).
Surface water runoff should be properly controlled to
prevent excessive erosion and soil loss. Establishment
of a healthy vegetative layer is key to protecting the
cover from erosion. However, consideration also must
be given to selecting plant species that are not deeply
rooted because they could damage the underlying infil-
tration layer (U.S. EPA, 1993).
12.3.2.5 Alternate Final Cover Design
An alternative material and/or an alternative thickness
may be used for an infiltration layer. For example, another
method for controlling erosion is the use of an armored
surface as the outer layer of a final cover system. An
armored surface or hardened cap is generally used in
arid regions or on steep slopes where the establishment
and maintenance of vegetation would be difficult (U.S.
EPA, 1993).
An armored surface (comprised of cobble-rich soils or
soils rich in weathered rock fragments) should have the
following characteristics (U.S. EPA, 1989b):
• Capable of remaining in place and minimizing erosion
of the armored layer and underlying material during
extreme weather events of rainfall and/or wind.
• Capable of accommodating settlement of the under-
lying material without compromising the component.
• Designed with a surface slope approximately the
same as the underlying soil.
• Capable of controlling the rate of erosion.
Asphalt and concrete may also be used to construct an
armored layer. These materials, however, deteriorate
due to thermal expansion and deformation caused by
subsidence. Crushed rock may be spread over the cover
in areas where weather conditions such as wind, heavy
rain, or temperature conditions commonly cause dete-
rioration of vegetative covers (U.S. EPA, 1989b).
On sites subject to Part 258 regulations, armored sur-
faces are considered an alternative final cover design and
may be employed in approved states only and with the
permission of'the'regulating authority (40 CFR 258.60 (b)).
12.3.2.6 Other Components for Final Cover
Systems
Other components that may be used in the final cover
system include a drainage layer, a gas vent layer, and a
biotic barrier layer. These components are shown in
Figure 12-5.
The Drainage Layer
The drainage layer is a permeable layer constructed
of soil or geosynthetic drainage material between the
erosion layer and the infiltration layer. The drainage
layer conveys water that has percolated through the
erosion layer away from contact with the infiltration
layer, thus reducing the potential for leachate genera-
tion (U.S. EPA, 1993).
A typical drainage layer consisting of soil material is at
least 12 in. (30 cm) thick wjth a hydraulic conductivity
between 10"2 and 10~3 cm/sec. The layer should be
sloped between two percent and five percent after set-
tling. The soil material should be no coarser than 3/8 in.
(0.95 cm), classified according to the Universal Soil
Classification System (USCS) as type SP, smooth and
rounded, and free of debris that could damage an un-
derlying geomembrane. Crushed stone is generally not
appropriate because of the sharpness of the particles
(U.S. EPA, 1993).
If geosynthetic materials are used as a drainage layer,
the fully saturated effective transmissivity should be the
equivalent of 1 foot of soil (30 cm) with a hydraulic
conductivity range of 10"2 to 10"3 cm/sec. Transmissivity
is calculated as the hydraulic conductivity multiplied by
the drainage layer thickness (U.S. EPA, 1993).
A filter layer composed of a low nutrient soil or a geo-
synthetic material (such as a non-woven needle punch
fabric) should be placed above the drainage layer. The
purpose of this layer is to prevent clogging of the drain-
age layer by roots and by the downward migration of
particles with the water.
The Gas Venting Layer
Sites with impermeable covers must have a system to
collect or disperse the combustible gas (methane) and
other harmful gases (such as hydrogen sulfide) that may
be generated during biodegradation of the sludge. The
218
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60cm
30cm
30 cm
20-mil FML—
or
60-milllDI'E
60 cm
\1// \l// \1//
Vegetation/
Soil-Top Layer
. Filler Layer
> Biulic Barrier Layer
• Drainage Layer
• Low-Permeability
FML/Soil Layer
Gas Venting Layer
Waste
Figure 12-5. Example of alternative final cover design incorporating other components that may be used in final cover systems
(U.S. EPA, 1993).
gas is collected in the gas vent layer. The gas vent layer
is usually 12 in. (30 cm) thick and should be located
between the infiltration layer and the sludge. Material
used in construction of the gas vent layer should be
medium to coarse-grained porous materials such as
those used in the drainage layer (U.S. EPA; 1993).
A system of horizontal pipes located throughout the gas
vent layer conveys the gases to vertical riser pipes or
lateral headers that penetrate the infiltration layer. If riser
pipes are used, they should be located at high points in
the cross-section. Design of the horizontal pipes should
incorporate some means to drain condensate that will
form in the pipes. If not drained, the condensate can
cause blockage of the pipes at low points. A more de-
tailed discussion concerning gas at active sewage
sludge units, including the use of active and passive
collection systems is provided in Section 7.8.2.
Gas vent pipe penetrations through the cover can cause
problems if settlement occurs. Settlement can cause
concentrated stresses at these points damaging the
cover and/or the vent pipes. If a geomembrahe is used
in the cover, adequate flexibility and slack material
should be provided at these points. If an active gas
collection system is used, penetrations may be made
through the sides of the cover directly above the liner
anchor trenches where effects of settlement would be
less pronounced (U.S. EPA, 1993).
The Biotic Layer
Deep plant routes or burrowing animals (collectively
called biointruders) may disrupt the drainage and
the low hydraulic conductivity layers, thereby interfer-
ing with the drainage capability of the layers. A 30-cm
(12-in.) biotic barrier of cobbles directly beneath the
erosion layer may stop the penetration of some deep-
rooted plants and the invasion of burrowing animals.
Most research on biotic barriers has been done in, and
is applicable to arid areas (U.S. EPA, 1993).
12.3.2.7 Other Design Issues
Hydrology
A computer model has been developed to assist design-
ers in evaluating the hydraulic performance of a cover
system. The Hydraulic Evaluation of Landfill Perform-
ance (HELP) Model was developed by the U.S. Army
Corps of Engineers for the EPA. This model is generally
accepted for use in designing landfill cover systems
(U.S. EPA, 1988).
The HELP program calculates daily, average, and peak
estimates of water movement across, into, through, and
out of landfills. Input parameters include soil properties,
climate-logical data, vegetation type, and site design
data. Output from the model includes precipitation, run-
off, percolation through the base of each cover layer
subprofile, evapotranspiration, and lateral drainage from
each profile. The model also calculates the maximum
head on the barrier soil layer of each subprofile and the
maximum and minimum soil moisture content of the
evaporative zone (U.S. EPA, 1993). (See Section 7.5.7.1
for more information on the HELP Model.)
Settlement
Excessive settlement and subsidence caused by
decomposition, dewatering and consolidation of
the sludge can impair the integrity of the cover sys-
tem. Specifically, settlement can contribute to
(U.S. EPA, 1993):
• Ponding of surface water
219
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• Disruption of gas collection pipe systems
* Fracturing of the infiltration layer
• Failure of geomembranes
Long-term settlement of disposal units should be ana-
lyzed on the basis of the deformation of the waste layers.
Settlement due to deformation of the waste layers is
most likely to occur after closure of the land disposal unit
and final placement of the cover. Therefore, this type of
settlement has more potential to cause subsidence
damage to the cover than consolidation settlement,
much of which can occur or can be made to occur prior
to closure (U.S. EPA, 1987a).
Settlement can occur within a few days of sludge place-
ment or extend over several years. Experience has indi-
cated that sites may require regrading up to five years after
closure. The rate and extent of settlement are controlled
by several variables including:
• Sludge characteristics
« Disposal method
• Soil characteristics
Of these, the characteristics of the sludge have the
greatest impact Relevant sludge characteristics include:
• Solids content
• Volatile solids content
• Particle size and configuration
Sludge with a low solids content (15 to 20 percent solids)
can be expected to settle more than sludge with a higher
solids content (28 percent solids). Sludge may dewater
due to evaporation, infiltration (into surrounding soils),
or separation. Dewatering results in an increase in pore
space and loss in volume, and consequent settling.
Sludge with a low solids content disposed in trenches
can stratify into liquid and solid phases. When this oc-
curs, the solid phase is subject to rapid settlement.
Other factors that influence the stability of the active
sewage sludge unit are the volatile solids content and
the size and configuration of the sludge particles.
Sludges with higher volatile solids content will biode-
grade more and result in a greater loss of volume and
increased settlement. Sludges with poorly sorted parti-
cles also settle to a greater extent.
Type of active sewage sludge units influence the poten-
tial for settlement. For example, landfill units in which
the sludge is bulked with soil will settle in a different
fashion from monofills.
Area fill disposal (where the sludge is not completely
contained) may experience horizontal movement or
creeping. Area fill sites are also susceptible to variable
climatic conditions that may affect site stability.
Soil characteristics also affect settlement. The amount
of interim and final cover applied will influence the
degree of settlement by applying a surcharge to the
sludge enhancing percolation of the liquid into the sur-
rounding soil. The ability of the cover material to bear
weight, inhibit water infiltration, and hold vegetation is
important when predicting settlement.
For co-disposal sites, good records regarding the type,
quantity, and location of solid waste materials disposed
will aid in estimating the amount of settlement expected.
Settlement due to consolidation may be minimized by
compacting the waste during daily operations of the
landfill or by landffiling baled waste (U.S. EPA, 1993).
If settlement is anticipated, several design options are
possible. For example, the cover thickness can be de-
signed such that after displacement occurs, surface
drainage is still adequate. Figure 12-6 illustrates this
design compensation method (U.S. EPA, 1988).
Slope Stability
Another potential cause of cover failure is displacement
due to slope instability. Slope stability analyses should
be performed to assess the potential for slope failure by
various failure modes (e.g., rotational, sliding, wedge)
as appropriate, based on the slope configuration. To
adequately perform stability analyses, the properties of
the cover system components, the sludge, and the foun-
dation soils must be known as well as seepage condi-
tions (U.S. EPA, 1988). A discussion of slope stability
can be found in Section 7.5.5.
12.3.3 The Stormwater Management System
Control of stormwater on site is important in the control
of erosion and surface water run-on and run-off. During
closure the site should be graded so there is no ponding
of surface water, and there is no run-on of precipitation
from off-site areas. Final grades of the site should be
designed so that after any settling has occurred, surface
slopes are between 2 and 5 percent. Drainage pipes and
ditches should convey all stormwater collected away
from the site.
12.4 Post-Closure Maintenance
12.4.1 Inspection Program
A program of regular maintenance is necessary to main-
tain the site in proper condition during the post-closure
period. The closure plan should contain an inspection
schedule and a list of maintenance activities to be
performed. Records of inspections detailing observations
should be maintained to record and monitor changes in
the site and its systems. These records also provide a
continuity of the inspection process regardless of
changes in the personnel conducting the inspections.
220
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5 percent slope
a. Before Settlement
Potential cracks
b. After Settlement
c. Thickenino cover before
and after settlement
Figure 12-6. Thickened cover for tolerance of settlement (U.S.
EPA, 1988).
Table 12-1 contains a list of typical inspection activities
for a surface disposal site.
Site inspections consist of a walkover to inspect the
systems and appurtenances and to look for evidence of
any developing problems at the site. Aerial photography.
can be useful, especially on larger sites to identify and
document the extent of any settlement or vegetative
stress. Aerial photography should be used in conjunc-
tion with, rather than as a. replacement for site walk-
overs. Optical topographic surveys can be used to quan-
tify and record the extent of settlement on the site.
12.4.2 Maintenance
A maintenance program must be developed to ensure
the continued integrity and effectiveness of the cover.
Preventative maintenance work should be scheduled
periodically for 2 to 3 years after coyer installation to
prevent loss of vegetation and gully development. Main-
tenance inspections should be regularly scheduled to
provide early warning of more serious problems devel-
oping that would impact the cover's integrity such as
cover subsidence, slope failure, leachate or upward
gas migration, or deterioration of the drainage system.
Figure 12-7 provides a brief overview of the elements of
a typical maintenance program (U.S. EPA, 1988). The
references U.S. EPA (1987b) and U.S. EPA (1982) pro-
vide detailed guidance on development of a post-closure
maintenance program.
12.4.2.1 Stormwater Management System
The stormwater management system should be in-
spected to ensure it has not become blocked or dam-
aged by subsidence. Drainage pipes should be
inspected and, as necessary, cleaned. Surface drainage
features should be cleared of unwanted vegetation,
silt, rocks, and other debris. Appurtenances such as
manholes and catch basins should be inspected for
damage and blockage..
12.4.2.2 Regrading
Regrading should be performed as necessary to main-
tain the integrity of the erosion layer. Inspections should
look for signs of soil erosion and settlement to be re-
paired by regrading. Erosion can cause formation of rills
that, if not repaired, can lead to exposure of the infiltra-
tion layer or the sludge. Settlement can cause depres-
sions and ponding of surface water or changes in
stormwater flow patterns.
12.4.2.3 Vegetation
Regular maintenance of the vegetative cover is impor-
tant to promote the growth of the desired vegetation.
The vegetation should be mowed at least twice a year
to suppress weeds and brush. Fertilizer and pesticides
should be applied as necessary to promote the desired
growth and to reduce pest damage.
The growth of undesirable plants can impair the vege-
tative cover. Deep rooted plants can penetrate and dam-
age underlying drainage and infiltration layers. If such
plants have become established, they should be com-
pletely removed and the remaining hole repaired. If the
roots are left in place, they can begin to grow again,
causing the problem to continue. Dead roots, as they
221
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Tabta 12-1. Checklist for Surface Disposal Site Inspection
Cover System • Look for formation of rills or other soil erosion damage.
• Look for indications of settlement such as depressions in the surface or ponding of stormwater.
• Look for indications of slope instability on steeper sideslopes.
• Look for signs of leachate outcrops.
"', ,/t , ,» ' , :
• Check the condition of the vegetation for indications of subsurface problems.
• Note the presence of any invader plant species.
• Look for any animal burrows.
Stormwater Management System
Be sure surface drainage features are clear and undamaged.
Be sure catch basins, manholes, and pipes are clean and unblocked.
Leachate Collection System
Be sure pipes are unblocked and undamaged by settlement.
Gas Vents
Be sure pipes are unblocked and undamaged by soil movement.
Be sure the infiltration layer is intact and properly sealed around vent pipes.
Qas Monitoring System
Test the gas monitoring equipment.
Other Facilities
Inspect roads, buildings, fences, etc., for signs olf wear, damage, or vandalism.
PREVENTATIV6 MAINTENANCE (2 to 3 years)
Cover System Component
Vegetation
Topsoil
Frequency
twice per year
annual
as needed
Task
mowing (weed and brush)
fertilization
soil reconditioning (supplemental
fertilization, aeration)
PROBLEM IDENTIFICATION/CORRECTION
Cover System Component
Cover System
Run-off Control System
Problem
gully development
subsidence
slope instability
gas migration that
causes cracking
erosion, siltato'on
Repair
backfill to original grade with stone of
narrow size range
regrade cover
replant vegetation
backfill with additional cover soil (care
should! be taken to maintain continuity
of low permeable soil layer,
geomembrarte and drainage layer)
reconstruct cover
flatten slopes
add toa berm along base of slope
upgrade or install gas venting system
install perimeter vents
placement of stone riprap or concrete
modify channel alignment and/or
gradients
Figure 12-7. Typical elements of maintenance program (U.S. EPA, 1988).
222
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decay, can provide a preferential pathway for rainwater
through the soil to the underlying layers.
Undesirable vegetation can provide a favorable habitat
for burrowing animals. If a site inspection reveals the
presence of animal burrows, they should be filled with
rocks and soil as a deterrent.
Site inspections should ajso monitor for signs of vege-
tative stress. This can be an indication of subsurface
problems that are otherwise undetectable. Unhealthy,
dying or dead plants can be indicators of settlement, or
leachate or gas leakage through the cover or liner.
12.4.2.4 The Leachate Collection System
On all active sewage sludge units that have liners and
leachate collection systems, the leachate collection sys-
tem must be maintained for 3 years during the post-clo-
sure period. Monitoring of the leachate quality should be
conducted as required by permits. The permitting
authority might require that ground water and the drain-
age from under the liner must be monitored to ensure
the performance of the liner system. Under Part 258, if
the owner/operator of an MSW landfill can show that the
leachate generated is no longer potentially harmful, per-
mission may be obtained to cease leachate monitoring.
The leachate collection system should be checked to
ensure that it is functioning properly. The pipes should
be inspected and cleaned regularly to prevent blockages
from forming. Leachate outcrops are an indication of a
rupture in the liner or the infiltration layer allowing pre-
cipitation to enter and leachate to escape. Failure of the
infiltration layer may be due to settlement, burrowing
animals, deep-rooted plants, or severe soil erosion.
12.4.2.5 Gas Monitoring and Collection System
Provisions must be made to monitor the concentration
of methane gas in air at the site for 3 years during the
post-closure period. Air must be monitored for methane
gas in any structure on the site and at the site property
line. Concentrations may not exceed 25 percent of the
Lower Explosive Level (LEL) in air in any structure within
the property line, and may not exceed the LEL in air at
the property line. For safety purposes, it should be
possible to measure methane levels within a structure
without entering it.
The gas collection system should be inspected to check
that it is working properly. Vent risers should be checked
to ensure that they are not clogged with foreign matter
such as dirt or rocks. The gas collection pipes should
be flushed and pressure cleaned as necessary. (See
Chapter 10 for additional information on monitoring for
methane gas.)
12.4.2.6 Site Access and Security
Public access to surface disposal sites must be re-
stricted for 3 years during the post-closure period. Other
sites may require some security measures to prevent
vandalism to structures, gas vents or other exposed
appurtenances. Traffic control devices may be required
to limit vehicles to areas where they will not damage a
cover system or other features of the site. The closure
plan should describe the security measures to be em-
ployed (fences, traffic barriers, signs, etc.).
Fences, traffic barriers, signs, etc., should be inspected
regularly. Site inspections should look for damage to the
site from vandalism and traffic, authorized or unauthor-
ized. Additional security measures should be added as
necessary. Any obvious health and safety hazards
should be remedied immediately.
12.5 References
1. U.S. EPA. 1994. Surface disposal of sewage sludge: A guide for
owners/operators of surface disposal facilities on the monitoring,
recordkeeping, and reporting requirements of the federal stand-
ards for the use or disposal of sewage sludge, 40 CFR Part 503.
EPA/831 /B-93/002C. Washington, DC (May).
2. U.S. EPA. 1993. Solid waste disposal facility'criteria. EPA/530/
R-93/017.
3. U.S. EPA. 1989a. Seminar publication: Requirements for hazard-
ous waste landfill design, construction, and closure. EPA/625/
4-89/022. Cincinnati, OH.
4. U.S. EPA. 1989b. Technical guidance document: Final covers on
hazardous waste landfills and surface impoundments.
EPA/530/SW-89/047. Washington, DC.
5. U.S. EPA. 1988. Guide to technical resources for the design of
land disposal facilities. EPA/625/6-88/018. Cincinnati, OH.
6. U.S. EPA. 1987a. Prediction/mitigation of subsidence damage to
hazardous waste landfill covers. EPA/600/2-87/025 (NTIS PB87-
175378).
7. U.S. EPA. 1987b. Design, construction, and maintenance of cover
systems for hazardous waste, an engineering guidance document.
NTIS PB87-191656. Vicksburg, MS: U.S. Army Engineer Water-
ways Experiment Station (May).
8. U.S. EPA. 1982. Standardized procedures for planting vegetation
on completed sanitary landfills. Grant no. CR-807673. Cincinnati,
OH: Municipal Environmental Research Laboratory (July).
223
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Chapter 13
Costs of Surface Disposal of Sewage Sludge
This section presents typical costs for sewage sludge
hauling, placement in a monofill or dedicated disposal
site, and placement in a municipal solid waste (MSW)
landfill. Costs for waste piles and surface impoundments
are not discussed. Cost curves are presented for sew-
age sludge hauling, monofilling, and dedicated disposal,
and are in terms of cost per wet ton vs. sludge quantity
received. Typical costs are presented for: (1) annualized
site capital costs, (2) site operating costs, and (3) total
site costs (combined annualized capital and operating).
These curves can be useful in the early stages of sludge
surface disposal site planning. Typical costs should be
used only in preliminary work, however. Actual costs
vary considerably with specific sludge and site condi-
tions. Therefore, use of these curves for computing
specific project costs is not recommended. Site-specific
cost investigations should be made in each case.
13.1 Hauling Costs
Typical costs for hauling dewatered sewage sludge are
presented in Figure 13-1. As shown, costs are given in
dollars per wet ton as a function of the wet tons of sludge
delivered to the site each day. Costs are presented for
alternative distances of 5,10,20, 30, 40, and 50 mi (8.0,
16.1, 32.2, 48.3, 64.4, and 80.4 km) hauls.
"Principals and Design Criteria for Sewage Sludge Ap-
plication on Land" (U.S. EPA, 1978) and 'Transport of
Sewage Sludge" (U.S. EPA, 1976) were the primary
sources of information for data and procedures in devel-
oping these hauling costs. Other references (U.S. EPA,
1975; Los Angeles/Orange County Metropolitan Area,
1977; Spray Waste, Inc., 1974) are available and also
were consulted and utilized. Sludge hauling costs were
originally prepared for the year 1975 but were updated
to reflect 1994 costs.
The hauling costs shown in Figure 13-1 reflect not only
transportation costs, but also the cost of sludge loading
and unloading facilities. For a treatment works generat-
ing wet tons (9.1 Mg) per day of a dewatered sludge and
a 5-mi (8.0-km) haul, sludge loading and unloading
facilities were found to contribute 60 percent of the total
hauling costs. For a treatment works generating ap-
proximately 250 wet tons (227 Mg) per day of dewatered
sludge and a 40-mi (64.4-km) haul, loading and unload-
ing facilities contributed less than 10 percent of the total
hauling costs.
Because of the differing bases for cost computations,
certain assumptions on sludge volumes and unit costs
were utilized to produce the hauling cost curve. These
assumptions include:
1. The sludge was dewatered and had a solids content
of approximately 20 percent. It was hauled by a 15
yd3 (11.5 m3), 3-axle dump truck.
2. Hauling was performed 8 hrs per day, 7 days per week.
3. Overhead and administrative costs were 25 percent
of the operating cost.
4. Capital costs were annualized. A rate of 7 percent
over 6 years was used for the trucks with a salvage
value of 15 percent. A rate of 7 percent over 25 years
was used for loading and unloading facilities with no
salvage value.
If conditions other than the above-stated conditions pre-
vail at a given site, the hauling costs in Figure 13-1
should be revised upward or downward appropriately.
As an example, if 10 yd3 (7.6 m3) 2-axle dump trucks
are used, costs should be higher by factors ranging from
1.3 for a treatment works generating 250 wet tons (227
Mg) per day with a 50-mi (80-km) haul, to 1.0 for a plant
generating 10 wet tons (9.1 Mg) per day with a 5-mi
(8.0-km) haul. Alternatively, if a 30 yd3 (23.9 m3) dump
truck is used, costs should be lower by factors ranging
from 0.6 to 1.0 for the aforementioned sludge quantities
and haul distances.
13.2 MonofHIs and MSW Landfills
13.2.1 Site Costs
Typical, site costs for monofilling sewage sludges are
presented in Figure 13-2, 13-3, and 13-4. As shown,
costs are given in dollars per wet ton of sewage sludge
received as a function of the wet ton of sewage sludge
delivered to the site each day. Costs are presented for
each of the alternative monofills regulated under Part
225
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One-way Haul Distance
•*• 5-Mile
•+• 10-Mile
20-Mile
30-Mile
40-Mile
50-Mile
$0
Figure 13-1. Typical Costs for Hauling Dewatered Sludge.
50
Wet Tons per Day
I
£L
I
$60
$50
$40
$30
$20
$10
$0
Type of MonofiU
•*• Area Pill Layer
•+• Area Fill Mound
*Diked Containment
•B-Narrow Tiench
•*• Wide Trench
•*-Codisposal with Soil
•A-Codisposai with Refuse
0
100
200 300
Wet Tons per Day
Figure 13-2. Capital Costs for Sludge Monofills and MSW Landfills.
400
500
226
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$200
$150
I •
$100
$50
$0
TypeofMonofill
•» Area Fill Layer
•+• Area Fill Mound
*Diked Containment
•&Narrow Trench
•* Wide Trench
•4-Codisposal with Soil
•A'Codisposal with Refuse
100
200 300
Wet Tons per Day
400
Figure 13-3. Operating Costs for Sludge Monofills and MSW Landfills.
$200
Type ofMonofm
-* Area Fill Layer
•+• Area Fill Mound
* Diked Containment
•& Narrow Trench
** Wide Trench
•4-Codisposal with Soil
ACodisposal with Refuse
200 300
Wet Tons per Day
Figure 13-4. Total Costs for Sludge Monofills and MSW Landfills.
227
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design dimensions and application rates were devised
for the purposes of these cost calculations. These sce-
narios are summarized in Table 13-1. The cost curve for
each method was plotted from computations that as-
sumed alternative quantities of 10, 100, and 500 wet
tons per day of sludge for each scenario.
Capital costs are summarized in Figure 13-2. Capital
cost items included:
1. Land.
2. Site preparation (clearing and grubbing, surface
water control ditches and ponds, monitoring wells,
soil stockpiles, roads, and facilities).
3. Equipment purchase.
4. Engineering. • ... ; •
Capital costs were then annualized at 7 percent interest
over 5 years (the life of the site) and divided by the
sludge quantity delivered to the site in one year to get
the capital cost per wet ton.
Operating costs are summarized in Figure 13-3. Oper-
ating cost items included:
1. Labor
2. Equipment fuel, maintenance and parts
3. Utilities
4. Laboratory analysis of water samples
5. Supplies and materials
6. Miscellaneous and other
Operating costs (see Figure 13-3) for one year were
then divided by the annual sludge quantity delivered to
the site to get the operating cost per wet ton.
The costs shown, which were derived from a variety of
published information sources (Equipment Guide Book
Company, 1977 and 1976; Robert Snow Means Com-
pany, 1978) and case study investigations, have been
revised upward to reflect 1994 prices. Several assump-
tions were employed in producing these cost curves.
These assumptions include:
1. Life of the surface disposal site was 5 years.
2. Actual fill areas (including inter-trench spaces)
consumed 50 percent of the total surface disposal
site area.
3. Engineering was 6 percent of the total capital cost.
It should be noted that the site costs shown for codis-
posal operations were derived by dividing the additional
annualized capital cost and additional operating cost by
the sludge quantity received. Actual unit costs for typical
MSW landfills not receiving sludge may be expected to
be less.
Figure 13-4 shows the total costs for monofills and MSW
units in which sewage sludge is placed.
13.3 Dedicated Disposal of Sewage
Sludge
Surface disposal on a dedicated surface disposal site
differs from land application programs in that the site is
used primarily or exclusively for the disposal of sewage
sludge. Sludge disposal rates are much higher for dedi-
cated disposal sites than for land application sites. Sew-
age sludge is often placed on a dedicated disposal site
throughout the year, except during inclement weather.
Figures 13-5 through 13-7 present base capital costs,
base annual operating and maintenance costs, and total
costs for sewage sludge disposed at a dedicated dis-
posal site: The assumptions used in developing these
curves are as follows:
1. The sludge has a solids content of approximately 5
percent.
2. Daily disposal period is 7 hours per day.
3. Annual disposal period is 200 days per year.
4. Fraction of land required in addition to disposal area
is 0.4 of the total surface disposal site.
5. The disposal rate is 30 to 50 dmt/ha/year.
13.4 Cost Analysis
As stated previously, the cost curves in this chapter
should not be used for site-specific cost compilations
performed during design. They can be useful, however,
in the preliminary planning stages of a surface disposal
site. In addition, they are useful in developing some
general conclusions about sludge surface disposal
costs. For instance: . .
1. Hauling costs ranged from less than $1 per wet ton
(less than $1 per Mg) for a 5-mi (8.1-km) haul of 500
wet tons (453 Mg) per day to $20 per wet ton ($22
per Mg) for a 50-mi (80.4-km) haul of 10 wet tons
(9.1 Mg) per day.
2. Annualized site capital costs ranged from $10 per
wet ton ($11 per Mg) for a sludge/solid waste
codisposal operation receiving 500 wet tons (453
Mg) per day to $47 per wet ton ($52 per Mg) for a»
diked containment operation receiving 10 wet tons
(9.1 Mg) per day.,
3. Site operating costs ranged from $5 per wet ton ($6
per Mg) for a sludge/solid waste codisposal operation
receiving 500 wet tons (453 Mg) per day to $154 per
wet ton ($169 per Mg) for an area fill mound
operation receiving 10 wet tons (9.1 Mg) per day.
229
-------
I
&
S2
$0
Wet Tons per Day
Figure 13-5. Capital Costs for Dedicated Surface Disposal Site.
4. Combined site costs ranged from $15 per wet ton
($17 per Mg) for a sludge/solid waste codisposal
operation receiving 500 wet tons (453 Mg) per day
to $197 per wet ton ($217 per Mg) for an area fill mound
operation receiving 10 wet tons (9.1 Mg) per day.
Also, an assessment can be made of the relative costs
of alternative types of sewage sludge units. A prioritized
list of these methods based on total site costs (see Figures
13-4 and 13-7) with lowest costs first is as follows:
1. Codisposal with sludge/solid waste mixture
2. Codisposal with sludge/soil mixture
3. Wide trench
4. Dedicated surface disposal site
5. Narrow trench
6. Diked containment
7. Area fill layer
8. Area fill mound
The cost of an active sewage sludge unit is determined
by the efficiency of the operation in terms of manpower,
equipment, and land use. Other factors, such as haul
distances play a role in the cost effectiveness of a given
site but are the same for the various methods.
As indicated, codisposal and wide trench methods tend
to be the most economical landfilling methods. Codis-
posal operations tend to be larger and benefit from the
economies of scale. In addition, the availability of "free"
bulking material in the form of solid waste reduces labor
costs. Wide trenches have high application rates and
are land and labor efficient. It should be noted, however,
that the relatively high solids content required for effec-
tive utilization of wide trenches will increase the cost of
sludge handling at the treatment plant.
Narrow trenches have relatively higher labor require-
ments and are intensive, contributing to high capital and
operating costs. Area fill mounds and layers are labor
and equipment intensive.
Diked containment requires a relatively large operation
before it becomes a cost-effective means of surface
230
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500
Wet Tons per Day
Figure 13-6. O&M Costs for Dedicated Surface Disposal Site.
disposal. This is a result of high initial labor and equip-
ment requirements. Once established, however, diked
containments are efficient in terms of operation and
land use.
13.5 References
1. Equipment Guide Book Company. 1977. Green guide, Vol. I: The
handbook of new and used construction equipment values.
2. Equipment Guide Book Company. 1976. Rental rate blue book for
construction equipment.
3. Los Angeles/Orange County Metropolitan Area. 1977. Sludge proc-
essing and disposal. A state-of-the art review. Regional Wastewa-
' ter Solids Management Program. .
4. Robert Snow Means Company. 1978. Building construction cost
data ,1978.
5. Spray Waste, Inc. 1974. The agricultural economics of sludge fer-
tilization. East Bay Municipal Utility District soil enrichment study.
Davis, CA.
6. U.S. EPA. 1978. Principals and design criteria for sewage sludge
application on land. Sludge treatment and disposal seminar hand-
out. U.S. Environmental Protection Agency.
c
7. U.S. EPA. 1976. Transport of sewage sludge. Contract No. 68-03-
2168. Cincinnati, OH.
8. U.S. EPA. 1975. Costs of wastewater treatment by land applica-
tion. Technical report. EPA-430/9-75/003. Washington, DC.
231
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$75
$60
I
I
I
o
$45
$30
$15
$0
5 50 500
Wet Tons per Day
Figure 13-7. Total costs for dedicated surface disposal site.
232
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Chapter 14
Design Examples
14.1 Introduction
The design of a surface disposal site is dependent on
sludge characteristics and site conditions, such as percent
solids, climate, soil, topography, and others. Consequently,
no design example can be universal. Examples can be
illustrative of the design and operating procedures that
have been recommended in the preceding chapters,
however.
This chapter contains three design examples. The ap-
proach in each of these examples is to present sludge
characteristics and site conditions as given design data.
The first example is for a large monofill receiving 25
percent solids sludge from a publicly owned treatment
works (POTW) serving a population equivalent of
200,000. In this example, the type of monofill is selected
early in the design process, and the design proceeds to
(1) determine design dimensions, (2) prepare site devel-
opment plans, (3) determine equipment and personnel
requirements, (4) develop operational procedures, and
(5) estimate costs. The second example is for a monofill
receiving 35 percent solids sludge from a POTW serving
a population equivalent of 50,000. In this example, two
alternative monofills appear to be equally suitable at
first. Alternate designs are performed for each before
one monofill is selected on the basis of costs. The third
design example is for a small POTW serving a popula-
tion equivalent of only 5,000. POTW management is
faced with a choice between monofilling .their 34 percent
solids sludge at the POTW site or disposing it at an
existing MSW landfill.
It should be noted that the scope of this chapter is
confined to design only. Siting and design considera-
tions for active sewage sludge units and surface dis-
posal sites influenced by regulatory requirements are
discussed in Chapters 4 and 7, respectively. It should
also be noted that the design described in this chapter
is somewhat preliminary in nature. A final design should
contain more detail and address other design considera-
tions (such as sediment and erosion controls, roads,
leachate control, etc.), which are not fully addressed
herein.
14.2 Design Example No. 1
14.2.1 Statement of Problem
The problem is to design a monofill at a pre-selected
site. The monofill is to receive a 35 percent solids sludge
from a POTW that serves a population equivalent of
200,000. The recommended design has to be (1) in
compliance with pertinent regulations, (2) environmen-
tally safe, and (3) cost-effective.
74.2.2 Design Data
The following information is the given design data.
14.2.2.1 Treatment Plant Description
The POTW is a secondary treatment works. Further
information on the POTW is as follows:
• Service population equivalent = 200,000
• Average daily flow rate = 20 MGD (0.86 m3/sec)
• Industrial inflow rate = 10 percent of total flow rate
• Wastewater treatment processes:
- Bar screen separation
- Aerated grit tanks
- Primary settling tanks
- Secondary aeration tanks
- Secondary settling tanks
14.2.2.2 Sludge Description
Sludge is generated primarily by two sources (primary
and secondary settling tanks). The sludge is stabilized
and dewatered. A more complete description is as fol-
lows:
• Sludge sources:
- Primary settling tanks
- Secondary settling tanks
• Sludge treatment:
- Gravity Thickening
- Mixing
233
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- Anaerobic digestion
- Vacuum filtration
• Sludge characteristics (based on testing, review of
records, and calculations)
- Solids content = 25 percent.
- Quantity on a dry weight basis = 13.0 dry tons/day
(11.8 Mg/day).
- Quantity on a wet weight basis = 52.0 wet tons/day
(47.1 Mg/day).
- Density = 1,700 Ibs/yd3 (1,009 kg/m3).
- Quantity on a wet volume basis = 61.2 yd3/day
(46.8m3/day).
14.2.2.3 Climate
Significant climatological factors having an impact on
monofilling are listed below:
• Preciptation = 32 in./yr (81 cm/yr).
• Evaporation = 28 in./yr (71 cm/yr).
• Number of days minimum temperature 32°F (0°C)
and below = 60 days/yr.
As shown, the climate at the site is relatively mild with
cold temperatures prevailing approximately two months
per year. Precipitation exceeds evaporation by 4 in./yr
(10 cm/yr)
14.2.2.4 General Site Description
Preliminary data were collected during the site selection
process. It is summarized below:
• Size of property = 375 acre (152 ha)
• Properly line frontage:
- 5,200 ft (1,580 m) along country road
- 4,700 ft (1,430 m) along residences
- 4,600 ft (1,400 m) along grazing land
- 1,200 ft (370 m) along woodland
• Slopes: Uniform slope of approximately 5 percent
• Vegetation:
- 225 acres (91 ha) of woodland
- 150 acres (60 ha) of grassland
• Surface water None on site
A plan view of the site is presented in Figure 14-1. As
shown, the site has good access along a county road.
The site is located in a moderately developed residential
area and abuts residences. Approximately 60 percent of
the site is covered with woodland. The balance of the
property is grass-covered.
14.2.2.5 Hydrogeology
Eight test borings were performed on the site to deter-
mine subsurface conditions. These were located as
shown in Figure 14-1. Subsurface conditions generally
are similar at all boring locations and can be summa-
rized as follows:
Depth Description
. 0-30 Clay
30-35 Siltysand
>35 Fractured crystalline rock
Ground water at the site is at a depth of 30 ft (9.0 m)
and bedrock is at a depth of 35 ft (10.5 m). Samples of
the clay were collected for analysis and the following
determinations made:
• Texture = fine
• Permeability = 2x8 cm/sec
• Permeability class = very slow
14.2.3 Design
14.2.3.1 Selecting a Monofill Type
Table 2-1 in Chapter 2 should be consulted as a refer-
ence for this section. The sludge to be disposed at the
site is stabilized. [Because the ground slope is relatively
flat at 5 percent, any of the monofill types discussed in
Chapter 2 would be suitable for final disposal of this
sludge. Because the sludge has a solids content of 25
percent, however, only narrow trenches and area fill
layers are considered for selection. A narrow trench
monofill was ultimately selected because ground water
and bedrock at the site are deep. Cover application, if
appropriate, would be via land-based equipment be-
cause of the solids content of the sludge (see Table 2-2
in Chapter 2). Soil should be used primarily for cover
and is not required for bulking.
14.2.3.2 Design Dimensions
Table 7-2 in Chapter 7 should be consulted as a refer-
ence for this section. As shown in this table, the design
dimensions to be determined for any trench operation
include the following:
1. Excavation depth
2. Spacing
3. Width
4. Length
5. Orientation
6. Sludge fill depth
7. Cover thickness
234
-------
0230900780JOOO
SCALE M FEET
PREVAILING
WINDS
PASTURE
200
PASTURE
LEGEND
- PROPERTY BOUNDARY
ROAD
DWELLING
WOODS
ZOO CONTOURS
Figure 14-1. Plan view of site in example number 1.
BORING
235
-------
The excavation depth is determined initially by the depth
to ground water or bedrock.1 A minimum separation of
2 to 5 ft (0.6 to 1.5 m) is usually provided between sludge
deposits and the top of bedrock or ground water. In this
case, a separation of 22 ft (6.6 m) was selected between
the excavation and ground water. The excavation depth
will be 8 ft (2.4 m).
Trench spacing is determined chiefly by sidewall stabil-
ity. As a general rule, 1.0 to 1.5 ft (0.30 to 0.46 m) of
spacing provided for every 1 ft (0.3 m) of trench depth.
Because the soil type is relatively stable, 1.0 ft (0.3 m)
of spacing for every 1 ft (0.3 m) of trench depth is
adequate for this site and the total spacing at the site
will be 8 ft (2.4 m).
Trench width is determined by sludge solids content and
equipment considerations. Because the sludge is only
25 percent solids, a 2- to 3-ft (0.6- to 0.9-m) width should
be used. At a width of 2 to 3 ft (0.6 to 0.9 m), the cover
soil creates a bridging effect over the sludge receiving
its support from solid ground on either side of the trench.
A backhoe is the most efficient piece of equipment for
excavations to an 8-ft (2.4-m) depth. For this site, a 2-ft
(0.6-m) width is specified based on the equipment effi-
ciency of the backhoe. The length for narrow trenches
is limited only by the need to place containment within
the trench to prevent low-solids sludge from flowing to
one end of a trench. Trench length is set at 200 ft (61
m). Thus, at every 200 ft (61 m) the trench is discontin-
ued for 5 ft (1.5 m) to provide containment. With regard
to trench orientation, trenches should be kept parallel to
one another to optimize land utilization. Because of the
relatively flat slopes at the site, it is not necessary to
orient the trenches parallel to topographic contours.
As shown in Table 7-2, for trench widths between 2 and
3 ft (0.6 and 0.9 m), the sludge fill depth should be within
1 to 2 ft (0.3 to 0.6 m) of the ground surface. Because
the excavation depth is greater than usual for a trench
of this width, sludge filling should proceed no closer than
2 ft (0.6 m) from the top. Cover application for a 2-ft
(0.6-m) wide trench should be from 2 to 3 ft (0.6 to 0.9
m) thick. The chosen cover thickness for this site is 3 ft
(0.9 m) due to the large sludge fill depth.
To test the practicality of these design dimensions, a
full-scale test was performed at the site. Initially, a back-
hoe was used to excavate two parallel trenches at the
previously-specified depth, width, and spacing. A10 yd3
(7.6 m3) dump truck (to be used in sludge hauling) was
then fully loaded with sludge and backed up to the
trench. Because the trench sidewall withstood the load,
the prescribed trench depth, width, and spacing were
found to be sound. Subsequently, the sludge load was
dumped into the trench, filling it to a 6-ft (1.8-m) depth.
About 3 ft (0.9 m) of cover was then gently applied over
the sludge by the backhoe. The cover was found to be
adequately supported at this time. At an inspection of
the test trenches several weeks later, no sludge had
emerged; however, the cover had settled almost 1 ft (0.3
m). Because this settlement could cause ponding of
rainwater over settled trenches in the future, the cover
application thickness is increased to a total of 4 ft (1.2
m) or to 2 ft (0.6. m) above grade. The design can
proceed based on the following design dimensions:
• Excavation depth = 8 ft (2.4 m).
• Spacing = 8 ft: (2.4 m).
• Width = 2 ft (0.6 m).
• Length = 200 ft (61 m).
• Orientation = trenches parallel to each other but not
necessarily parallel to .contours.
• Sludge fill depth = 6 ft (1.8 m).
• Cover thickness = ,4 ft (1.2 m).
14.2.3.3 Site Development
Site development is in accordance with the plan shown in
Figure 14-2. Features of this plan included the following:
• A 300-ft (91-m) wooded buffer is maintained between
the sludge fill area and residences. A 200-ft (61-m)
buffer is maintained around the balance of the property.
* Trenches are installed along the downhill (southeast-
ern) property line to collect storm water runoff.2 A
sedimentation pond is constructed to receive runoff
collected by these trenches.
• In accordance with engineering judgment, one
ground-water monitoring well is located upgradient
from the fill area and five monitoring wells are located
down-gradient from the fill area.
• The site is divided into nine active sewage sludge
units so that the site can be cleared in phases. In this
way, clearing can proceed approximately once each
year in advance of sludge surface disposal operations.
• The active sewage sludge unit located nearest to the
site entrance is designated for wet weather operations.
The access road to this area is paved with asphalt.
• The remaining access roads are covered with gravel.
• After providing area for buffers, access roads, facili-
ties, etc., approximately 156 acres (63 ha) remain for
active sewage sludge units out of the entire 375 acres
(152 ha) on the site.
1 Th0 Part 503 requirements related to contamination of ground water
are discussed In Chapters 3, 6, and 7.
2 These trenches are designed to have the capacity to handle runoff
from a 24-hour, 25-year storm event in line with Part 503 requirements.
236
-------
£«•'
-
«
I
8
cs
5*
•**•
m
•VY
230 900 750 1000
SCALE IN FEET
PREVAILING
WINDS
WSTURE
PASTURE
a
LEGEND
— PROPERTY BOUNDARY
:ROAD
DWELLING
WOODS
ASPHALT PAVED ACCESS ROAD
• — GRAVEL ACCESS ROAD
) SEDIMENTATION POND
MONITORING WELL
SLUDGE FILL AREA
Figure 14-2. Site development plan for example number 1.
237
-------
14.2.3.4 Calculations
Based on the design data and dimensions stated pre-
viously, calculations can be made of the (1) trench utili-
zation rate, (2) sludge disposal rate, (3) land utilization
rate, and (4) site life.
1. Trench utilization rate
sludge volume per day
cross-sectional area of sludge in trench .
m sludge volume per day
(trench fill depth) x (trench width)
(61.2 yd3/day) x (27 ft3/yd3)
(6 ft) x (2 ft) ,
- 138 ft/day (41.4 m/day)
2. Sludge disposal rate
cross-sectional area of sludge in trench
width of trench + spacing
_ (6 ft) x (2 ft) _ 12 ft2 __ 12 ft3
= (2 ft) + (8 ft) 10 ft 10 ft2
(12 ft3)(1 yd3/27 ft3)
(10 f1?)(1 acre/43,506 ft2)
- 1,936 yd3/acre (3,659 m3/ha)
3. Land utilization rate
_ sludge volume per day
sludge application rate
61.2 yd3/day
1,936 yd3/acre
- 0.0316 acres/0.0128 ha/day)
4. Site life =
usable fill area
land utilization rate
156 acres 4,937 days
0.0316 acres/day 365 days/year
=• 13.5 years
14.2.3.5 Equipment and Personnel
Table 9-4 in Chapter 9 should be consulted as a refer-
ence for this section. As shown, for a narrow trench
operation receiving between 50 and 100 wet tons per
day (45 and 91 Mg per day), the following equipment
might be selected:
Description
Track backhoa with loader
Quantity
1
Hours per Week
15
Track dozer
Total
30
The use of a backhoe was already established during
the selection of design dimensions. Therefore, the
above suggested scheme was implemented. The duties
and number of personnel are also established at this
stage and include:
Description Quantity Hours per Week
Backhoe operator 1 40
Backhoe and dozer operator 1 40
Total 2 80
Operations are conducted at the site 8 hours per day
and 7 days per week to coincide with sludge deliveries
and avoid the added cost and odors often encountered
with sludge storage facilities. The backhoe is operated
7 hours per day (plus 1 hour downtime per day for
routine maintenance and cleanup) and 7 days per week.
The dozer is operated 3 hours per day (plus 1 hour
downtime per day for routine maintenance and cleanup)
and 5 days per week. One full-time operator works 8
hours per day Monday through Friday. He is responsible
for operating arid maintaining the backhoe during these
hours. The other operator works 8 hours per day
Wednesday through Sunday; he is responsible for (1)
operating and maintaining the backhoe for 8 hours each
day on Saturday and Sunday, (2) operating and main-
taining the dozer for 4 hours each day on Monday
through Friday, and (3) performing miscellaneous func-
tions such as check station attendant, compiling site
records, etc.
14.2.3.6 Operational Procedures
Site preparation consisted of the following procedures:
1. Initially, active sewage sludge unit No. 1 and the
inclement weather area are cleared and grubbed.
Roads providing access to these areas are paved
with asphalt or gravel (as shown In Figure 14-2).
Several trenches are excavated in the inclement
weather area and the soil stockpiled alongside each
trench. Runoff, erosion, and sedimentation controls
as well as monitoring wells are installed.
2. At least 1 month (but never more than 4 months) in
advance of the fill operation, each new active sew-
age sludge unit is cleared and grubbed. Usually
these operations occur once each year and are
timed to avoid cold temperatures and frozen ground
conditions. The work is performed by equipment and
personnel brought in specifically for this task. Debris
is disposed of on-site by burial and/or by producing
wood chips.
On-going operations consist of the following:
1. Trenching begins in the corner of each active sew-
age sludge unit furthest removed from the access
road and proceeds generally toward the road as it is
completed.
238
-------
vides contingency capacity for slightly more than one
day's sludge receipt.
3. Trenches are excavated to design dimensions by the
track backhoe as it straddles the excavation (see
Figure 14-3).
4. Haul vehicles back-up to the previously excavated
trench and dump sludge loads directly into the
trench. Filling proceeds to approximately 2 ft (0.6 m)
below the top of the trench. Because of its low solids
content, sludge flows evenly throughout the trench
and accumulations at one location are minimized.
5. Within 1 hour after sludge-filling has occurred in one
location, the track backhoe excavates a new trench
adjacent to the filled trench. Excavated material from
the new trench is applied as cover over the adjacent
sludge-filled trench. The cover is applied carefully
• from a low height at first to minimize the amount of
cover sinking into sludge deposits. Subsequently,
cover is applied less carefully. Ultimately, the cover
extends to 2 ft (0.6 m) above grade.
Site completion consists of the following procedures:
1. Approximately 1 month after completion of each 1-
acre (0.405-ha) portion of an active sewage sludge
unit, the bulldozer is used to regrade the area to a
smooth ground surface.
2. Immediately thereafter, the unit is hydroseeded (as-
suming weather conditions permit) and grasses soon
take root.
14.2.3.7 Cost Estimates
Based on the site design, cost estimates were prepared
for capital and operating costs in Tables 14-1 and 14-2,
respectively. As shown, the total capital cost of the site
is estimated at $3,474,945. Considering a site capacity
of 260,000 wet tons (236,000 Mg) of sludge, the capital
cost is $13.31 per wet ton (14.81 per Mg).
Section x-x
Figure 14-3. Operational procedures for example number 1.
239
-------
Table 14-1. Estimate of Total Site Capital Costs for Example Number 1
Item
Land
Site Preparation
Clearing and Grubbing
Sodded Runoff Ditch
Pond
Monitoring Wells
Garage
Gravel Roads
Asphalt Roads
Miscellaneous
Equipment
Backhoe
Dozer
Subtotal
Engineering at 6%
Total
Quantity
375 acres
45 acres .
4,000ft
1 ea
6ea
1,600 sq ft
1,500ft
1,000ft
1 ea
1 ea
Unit Cost
$7,500 /acre
$1 ,250 /acre
$5 /ft
$25,000 /ea
$2,000 /ea
$30/sqft
$25 /ft
$42 /ft
$100,000 /ea
$95,000 /ea
Total Cost
$2,812,500
56,250
20,000
25,000
12,000
48,000
37,500
42,000
20,000
100,000
95,000
3,268,250
196,095
3,464,345
Table 14-2. Estimate of Annual Operating Costs for Example Number 1
Item
Labor
Backhoe Operator
Backhoo/Dozor Operator
Equipment Fuel, Maintenance, Parts
Backhoe
Dozer
Clearing and Grubbing
Gravel Roads
Office Trainer Rental
Utilities
Laboratory Analyses
Supplies and Materials
Miscellaneous
Total
Quantity •
2,080 hrs
2,080 hrs
2,555 hrs
780 hrs
10 acres
1,500 ft
1 ea
Unit Cost
$1(i/hr
$1« /hr
15.5ei /hr
10.1JI /hr
$1,250 /acre
$25! /ft
$1 0,000 /ea
Total Cost
$37,440
37,440
39,756
7,940
12,500
37,500
10,000
10.000
14,400
20,000
20,000
246,976
As shown in Table 14-2, the annual operating cost is
estimated at $246,976. Considering an annual receipt of
25,000 wet tons (22,700 Mg) of sludge, the unit operat-
ing cost is $9.88 per wet ton ($10.80 per Mg). Combined
capital and operating costs are estimated at $23.25 per
wet ton ($25.71 per Mg).
14.3 Design Example No. 2
14.3.1 Statement of Problem
The problem is to design a monofill at a pre-selected
site. The monofill is to receive a 35 percent solids sludge
from a proposed POTW that will serve a population
equivalent of 50,000. The recommended design has to
be (1) in compliance with pertinent regulations, (2) en-
vironmentally safe, and (3) cost-effective.
14.3.2 Design Data
The following information is the given design data.
14.3.2.1 Treatment Plant Description
The proposed POTW is a secondary treatment work.
Further information on the POTW is as follows:
• Service population equivalent = 50,000
240
-------
• Average flow = 5.0 MgaVd (0.22 rrrVsec)
• Industrial inflow = 0 percent of total inflow
• Wastewater treatment processes:
- Bar screen separation
- Primary clarifier
- Secondary clarifier
- Sand filters
- Chlorine contact tanks
14.3.2.2 Sludge Description
Sludge is to be generated primarily from two sources
(primary and secondary clarifiers). The sludge will be
anaerobically digested and dewatered. A more complete
description is as follows:
• Sludge sources:
- Primary clarifiers
— Secondary clarifiers
• Sludge treatment:
- Gravity thickening
- Mixing
- Anaerobic digestion
- Dewatering via belt presses
• Sludge characteristics (based on treatment plant de-
sign report).
- Solids content = 35 percent.
- Quantity on a dry weight basis = 3.25 dry tons/day
(2.95 Mg/day).
— Quantity on a wet weight basis = 9.3 wet tons/day
(8.5 Mg/day).
- Density = 1,750 Ibs/yd3 (1,039 kg/m3).
— Quantity on a wet volume basis.
9.3 tons/day x (2,000 Ibs/ton)
1,750
- = 10.6 yd3/day (8.1 m3/day)
14.3.2.3 Climate
Significant climatological factors having an impact on
surface disposal are listed below:
• Precipitation = 48 in./yr (122 cm/yr).
• Evaporation = 30 in./yr (76 cm/yr).
• Number of days minimum temperature 32°F (0°C)
and below = 125 days/yr.
As shown, the climate is quite cold with freezing tem-
peratures prevailing during 4 months of the year. Pre-
cipitation is high and evaporation exceeds precipitation
by 18in./yr(46cm/yr).
14.3.2.4 General Site Description
Site data were collected from existing information sources
as well as field investigations performed during the site
selection process. These data are summarized below:
• Size of property = 12 acres
• Property line frontage:
- 1,750 ft (533 m) along woodland.
- 500 ft (152 m) along cropland.
- 850 ft (259 m) along a county road with woodland
on the other side.
• Slopes = relatively flat with slopes at approximately
2 percent.
• Vegetation:
- 6.5 acres (2.6 ha) of woodland.
- 5.5 acres (2.2 ha) of open space sparsely covered
with grasses.
• Surface water = none on site; drainage on site via
overland sheet flow into roadside ditch.
A plan view of the site is presented in Figure 14-4. As
shown, the site has good access from a two-lane county
road adjoining the property. Approximately one-half of'
the site is wooded; the balance is open space with some
grasses. Cropland adjoins the property to the east. Other
adjoining properties are undeveloped and wooded.
14.3.2.5 Hydrogeology
During the site selection phase, soil maps for the area
were reviewed. In addition, logs of soil borings and wells
drilled near the site were examined. Historical records
compiled on nearby drinking water wells were reviewed
for ground-water levels and seasonal fluctuations.
Subsequent to the site selection, four soil borings were
performed at the site to verify subsurface conditions. These
borings are located as shown in Figure 14-4. Subsurface
conditions were found to be somewhat consistent at all
boring locations and can be summarized as follows:
Depth
0-5 ft (0-1.5m)
>5ft(>1.5m)
Description
Coarse sand with silty sand
Saturated coarse sand
The soil at the site is primarily a coarse sand; however,
the sand had some layers of silty sand interspersed
throughout. Ground water is at a depth of 5 ft (1.5 m).
Due to the site's location on the coastal plain, bedrock
is deep. Samples of the coarse sand were collected for
analysis and the following determinations were made.
• Texture = coarse
• Permeability = 8 x 10"4 cm/sec
• Permeability class = moderately rapid
241
-------
100 ZOO 300
E55"'"
SCALE IN FEET
LEGEND
- PROPERTY BOUNDARY
r COUNTY ROAD
CROP LAND
&&<&£; WOODS
200 CONTOURS
S BORING
Figure 14-4. Site base map for example number 2.
74.3.3 Design
14.3.3.1 Selecting a Monofill Type
Table 2-1 in Chapter 2 should be consulted as a refer-
ence for this section. Because the sludge is stabilized
and has a solids content of 35 percent, this sludge can
be disposed in any of the types of monofill described in
Table 2-1. None of these monofills are disqualified on
the basis of sloping requirements, because the site is
relatively flat (2 percent slopes).
Because the site is relatively small and a longer site life
is desired, it becomes obvious early in the design proc-
ess that a high sludge disposal rate is required. As
shown in Table 2-2 in Chapter 2, the highest sludge
disposal rates are attained with wide trenches, area fill
mounds, and diked containments. Diked containment is
ruled out because the high disposal rates sometimes
achieved with this type of monofill are only possible for
large diked containments (with high dikes) receiving
large quantities of sludge. Wide trenches are initially
selected based on the cost-effectiveness of this opera-
tion versus area fill mounds. Normally a 5-ft (1.5-m)
depth to ground water is sufficient to allow trench exca-
vation and still provide sufficient buffer soils. The soil's
coarse texture and moderately rapid permeability at this
site, however, indicated a strong potential for contami-
nant movement without a liner. Therefore, subsurface
242
-------
placement of sludge in wide trenches lined with recom-
pacted clay and gee-membranes is one proposed mon-
ofilltype.
Surface disposal of sludge in area fill mounds is retained
as a possible disposal option even though area fill
mounds have disadvantages in high precipitation areas
such as at this site.
14.3.3.2 Design Dimensions
Preliminary designs are performed for each type of mon-
ofill still under consideration. The purpose of these de-
signs is to provide a basis for the site life and cost for
each method in order to select the best disposal method.
Using Tables 7-2 and 7-4 in Chapter 7, dimensions are
computed for each method as shown in Table 14-3.
14.3.3.3 Site Development
Site development is planned in accordance with Figures
14-5 and 14-6 for wide trench and area fill mound op-
erations, respectively. Features included in both plans
are as follows:
1. A buffer is maintained to all adjoining property. Where
wooded areas exist along property frontages, a
100-ft (30-m) wide strip is maintained in its natural
state. Where grassy open space areas exist along
property frontages, a 150-ft (46-m) wide strip is un-
disturbed.
2. A sodded diversion ditch is included along the uphill
side of the site to intercept upland drainage. Intercepted
runoff is directed to existing roadside ditches.3
dimensions of these drainage devices are checked to ensure
they have the capacity to handle runoff from a 24-hour, 25-year storm
event in line with Part 503 requirements.
3. A sodded collection ditch was included along the down-
hill side of the site to intercept on-site drainage. Inter-
cepted runoff was directed to a new sedimentation pond.
Features specific to the wide trench operation shown in
Figure 14-4 included the following:
1. Trenches are laid out in accordance with design
dimensions and make optimal use of available land.
2. Gravel roads are constructed as shown to provide
access from the site entrance to individual trenches.
3. A liner system is installed including 2 ft of recompacted
clay of 1 x 10'7 cm/sec permeability, plus 60 mil HOPE
geomembrane along the bottom and sideslopes. A
leachate collection system is installed on the floor
above this. ;
Features specific to the area fill mound operation shown
in Figure 14-5 included the following:
1. An asphalt-paved dumping/mixing pad and access
road is specified.
2. A soil stockpile area is located near the dumping/
mixing pad. Soil for this stockpile is imported once
each year from another location incurring a 3-mile haul.
3. Most of the remaining site area is designated for
surface disposal operations.
14.3.3.4 Calculations
Based on the design data and dimensions stated pre-
viously, calculations are performed for each of the pro-
posed monofill types. Determinations made on the wide
trench application include:
• Trench capacity = 1,481 yd3/trench (1,132 m3/trench).
• Number of trenches = 12
• Site capacity = 17,772 yd3/trench (13,588 m3)
Table 14-3. Design Considerations for Example Number 2
Design Consideration
Width
Depth
Length
Spacing
Bulking Performed
Bulking Agent
Bulking Ratio
Sludge Depth Per Lift
Number of Lifts
Cover Applied
Location of Equipment
Interim Cover Thickness
Final Cover Thickness
Imported Soil Required
Wide Trench
50ft
8ft
200ft
20ft
No
— —
— .—
4ft
1
Yes
Sludge-Based
—
4ft
No
Area Fill Mound
—
—
—
Yes
Soil
1 Soil : 1 Sludge
6ft
1
Yes
Sludge-Based
—
3ft
Yes
:243
-------
100 tOO 3OO
9__sae=
•CALK IN FEET
CROP LAND
C.OP
LEGEND
PROPERTY BOUNDARY
COUNTY ROAD
R WOODS
ASPHALT PAVEMENT
K\N MOUND AREA
*-DIVERSION DITCH
COLLECTION DITCH
SEDIMENTATION POND
Figure 14-5. Site development plan for example number 2 area fill mound.
• Sludge volume received = 10.6 yd3/day (8.1 m3/day)
• Site life = 4.6 years
Determinations made on the area fill mound-application
include:
• Sludge application rate = 9,680 yd3/acre (18,295 rrvVha)
• Size of mounding area = 3 acres (1.22 ha)
• Site capacity = 29,040 yd3 (22,204 m3)
• Sludge volume received = 10.6 yd3/day (8.1 rrvVday)
• Site life = 7.5 years
14.3.3.5 Equipment and Personnel
Using Table 9-4 in Chapter 9 as a reference, the follow-
ing equipment and personnel were selected for use at
the wide trench operation:
Description
Track Dozer
Track Dozer Operator
Quantity
1
1
Hours per Week
10
10
The following equipment and personnel were selected
for use at the area fill mound operation:
Description Quantity Hours per Week
Track Loader 1 15
Track Loader Operator • 1 20
14.3.3.6 Cost Estimates
Cost estimates were computed for each of the proposed
monofill types. These estimates have been included as
Tables 14-4 through 14-7. As shown, the annual opera-
tion cost of the wide trench operations is calculated at
$55,334. The capital cost is calculated at $511,573.
244
-------
900
CROP LAND
LEGEND
PROPERTY BOUNDARY
• COUNTY ROAD
* WOODS
TRENCH
DIVERSION DITCH
COLLECTION DITCH
SEDIMENTATION POND
GRAVEL ROAD
Figure 14-6. Site development plan for example number 2 wide fill trench.
The annual operating cost of the area fill mound is
calculated at $70,570. The total capital cost is calculated
at $514,276. Unit costs for each monofill are summa-
rized below:
Wide Trench
Area Fill
Mound
14.3.3.7 Conclusion
An area fill mound is selected and utilized. Although the
area fill mound actually costs more than the wide trench,
the cost difference is not that substantial and the area
fill mound's longer life makes it the clear-cut choice for
the surface disposal site.
Capital Cost
$36.94/wet ton
($40.74/Mg)
$27.40/wet ton
($29.42/Mg)
Operating
Cost
$13.54/wet ton
($14.93/Mg)
$26.92/wet ton
($29.03/Mg)
Total Cost
$50.48/wet ton
($55.67/Mg)
$52.72/wet ton
($58.14/Mg)
14.4 Design Example No. 3
14.4.1 Statement of Problem
The problem is to design a monofill on the site of a
POTW serving a population equivalent of 5,000. The
POTW had been disposing of their 34 percent solids
sludge at an MSW landfill 8 miles (13 km) distant; how-
ever, landfill operators now are charging $60.00 per wet
ton ($66.15 per Mg) for the sludge. Therefore, POTW
operators are seeking the cost-savings that might be
realized by surface disposal of the sludge themselves.
The recommended design has to be (1) in compliance
with pertinent regulations, (2) environmentally safe, and
(3) cost-effective.
14.4.2 Design Data
The following information is the given design data.
245
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Table 14-4. Estimate of Total Site Capital Costs for Example Number 2 Wide Trench
Item
Land
Site Preparation
Clearing and Grubbing
Sodded Division Ditch
Sodded Collection Ditch
Pond
Recompacted Clay Liner
Geomembrane
Leachate Collection
Monitoring Wells
Gravel Roads
Miscellaneous
Equipment
Track Dozer
Subtotal
Engineering at 6%
Total
Quantity
12 acres
6 acres
1,750ft
850ft
1 ea
9,680 cu yd
130,680 sqft
9,680 cu yd
Sea
950ft
1 ea
Unit Cost
$7,500 /acre
$1,250 /acre
$5 /ft
$5 /ft
$10.000/63
$7 /cu yd
$0.45 /sq ft
$10/cuyd
$2,000 /ea
$25 /ft
$95,000 /ea
Total Cost
$90,000
7.500
8,750
4,250
10,000
67,760
58,806
96,800
10,000
23,750
10,000
95,000
482,616
28.957
J
511,573
Table 14-5. Estimate of Annual Operating Costs for Example Number 2 Wide Trench
Item
Labor
Dozer Operator
Equipment Fuel, Maintenance, Parts
Track Dozer
Leachate Management
Laboratory Analyses
Other Supplies and Materials
Miscellaneous
Total
Quantity
780 hrs
520 hrs
20,000 gallons
Unit Cost
$18 /hr
10.1 8 /hr
$0.20 /gallon
Total Cost
$14,040
5,294
4,000
12,000
10,000
10,000
55,334
14.4.2.1 Treatment Plant Description
The POTW is a package plant. Further information on
the POTW is as follows:
• Service population equivalent = 5,000
• Average flow = 0.5 Mgal/d (0.022 m3/sec)
• Industrial inflow = 0 percent of total inflow
• Wastewater treatment processes:
— Bar screen separation
- Primary clarifier
— Aeration tanks
— Secondary clarifier
14.4.2.2 Sludge Description
Sludge from the secondary clarifier is recirculated to the
primary clarifier. The sludge is stabilized and dewatered.
A more complete description is as follows:
• Sludge sources—sludge from secondary clarifier re-
circulated to primary clarifier and withdrawn as mix-
ture with primary sludge.
• Sludge treatment:
- Aerobic digestion
- Dewatering via sand drying beds
• Sludge characteristics (based on testing, review of
records, and calculations).
- Solids content = 34 percent.
246
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Table 14-6. Estimate of Total Site Capital Costs for Example Number 2 Area Fill Mound
Item
Land
Site Preparation
Clearing and Grubbing
Sodded Division Ditch
Sodded Collection Ditch
Pond
Recompacted Clay Liner
Geomembrane
Leachate Collection
Monitoring Wells
Asphalt Paving
Miscellaneous
Equipment
Track Dozer
Subtotal
Engineering at 6%
Total
Quantity
12 acres
6 acres
1,750ft
850ft
1 ea
9,680 cu yd
1 30,680 sq ft
9,680 cu yd
Sea
4,200 sq ft
1 ea
Unit Cost
$7,500 /acre
$1,250 /acre
$5 /ft
$5 /ft
$1 0,000 /ea
$7 /cu yd
$0.45 /sq ft
$10/cuyd
$2,000 /ea
$2 /sq ft
$120,000 /ea
Total Cost
$90,000
7,500
8,750
4,250
10,000
67,760
58,806
96,800
10,000
6,300
5,000
120,000
485,166
29,110
514,276
Table 14-7. Estimate of Annual Operating Costs for Example Number 2 Area Fill Mound
Item
Labor
Loader Operators
Equipment Fuel, Maintenance, Parts
Track Dozer
Leachate Management
Laboratory Analyses
Other Supplies and Materials
Miscellaneous
Total
Quantity
1,040 hrs
780 hrs
20,000 gallons
Unit Cost
$18 /hr
20.32 /hr
$0.20 /gallon
Total Cost
$18.720
15,850
4,000
12,000
10,000
10,000
70,570
- Quantity on a dry weight basis = 0.33 dry tons/day
(0.30 Mg/day).
- Quantity on a wet weight basis = 0.96 wet tons/day
(0.87 Mg/day).
- Density- 1,850 Ibs/yd3/day (1,098 kg/m3).
— Quantity on a wet volume basis = 1.03 yd3/day
(0.79 m3/day).
14.4.2.3 Climate
Significant climatological factors having an impact on
surface disposal are listed below:
• Precipitation = 32 in./yr (81.3 cm/yr).
• Evaporation = 34 in./yr (86.4 cm/yr).
• Number of days minimum temperature 32°F (0°C)
and below = 40 days/yr.
The climate of the site is marked by mild temperatures.
Precipitation is moderate and is exceeded slightly by
evaporation.
14.4.2.4 General Site Description
The area to be used for a surface disposal site occupies
a 3-acre (1.2-ha) portion of the 8-acre (3.2-ha) treatment
plant property. It is located immediately adjacent to the
POTW's sand drying beds. Other data concerning this
3-acre tract is summarized below:
247
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• Adjoining properties:
— 700 ft (210 m) abuts woodland which is privately
owned.
- 700 ft (210 m) abuts POTW.
• Slopes = evenly sloped at about 6 percent.
• Vegetation = all 3 acres (1.2 ha) had been previously
cleared and are covered with grasses.
• Surface water = none of the 3-acre (1.2 ha) tract. A
stream which receives effluent from the treatment
facility is located 500 ft (150 m) away.
14.4.2.5 Hydrogeology
Site hydrogeological data was collected largely from
information contained in the POTW report and drawings.
Some additional information on soils, bedrock, and
ground water was obtained from the sources listed in
Chapter 6.
Subsurface conditions are summarized as follows:
Depth
0-10 ft (0-3.0 m)
10-12 ft (3.0-3.7 m)
12-15 ft (3.7-4.6 m)
15-26 ft (4.6-7.9 m)
>26 ft (7.9 m)
Description
Silly clay with some clay lenses
Interspersed throughout
Saturated silty clay
Clay
Saturated silty clay
Bedrock
The upper 10 ft (3.0-m) of soil was a dry silty clay and
ground water was encountered at 10 ft (3.0 m). A 3-ft
(0.9-m) thick tight clay seam protects the ground water
located below it. Using Table 4-2 and Figures 4-8 and
4-9, the following determinations were made:
• Texture = fine
• Permeability = approximately 1 x 10"7 cm/sec
• Permeability class = very slow
14.4.3 Design
14.4.3.1 Selecting a Monofill Type
This site is conducive to subsurface placement of sludge
because ground water and bedrock are relatively deep
(at 10 and 26 ft [3.0 and 7.9 m], respectively), and the
soils are tight enough to afford sufficient environmental
protection. Because area fills are generally more man-
power and equipment-intensive then are trenches,
trenches should be selected in almost all instances
where hydrogeologic conditions allow. In addition, wide
trenches should be selected over narrow trenches for
sludge with a solids content of 34 percent. An active
sewage sludge unit liner is desirable (geomembrane
only). Cover application, if appropriate, should be via
sludge-based equipment. All of these considerations
were established and utilized in the preliminary design.
14.4.3.2 Design Dimensions
The following design dimensions were established:
• Width = 20 ft (6.1 m)
• Depth = 8 ft (2.4 m)
• Length = 100ft (30 m)
• Spacing = 30 ft (9.1 m)
• Sludge fill depth = 5 ft (1.5 m)
• Cover thickness = 4 ft (1,2 m)
Test trenches were then constructed on the site and
operated under proposed conditions to ensure their ef-
fectiveness and practicality in a full-scale operation. The
test was successful and the design proceeded based on
the above dimensions.
14.4.3.3 Calculations
Based on the design data and dimensions stated pre-
viously, calculations were performed for each of the
proposed monofills. Determinations made on the opera-
tion included:
• Trench capacity = 375 yd3 (287 m3)
• Number of trenches = 20
• Site capacity == 7,500 yd3 (5,734 m3)
• Sludge volume received = 1.03 yd3/day (0.79 m3/day)
• Site life = 20 years
14.4.3.4 Operational Procedures
Site preparation, on-going operations, and site comple-
tion consist of the following procedures:
1. Twice each year a contractor is employed to exca-
vate sufficient trench capacity for a 6-month sludge
quantity. The contractor uses a single front-end
loader to excavate each 20-ft (6.1-m) wide trench to
a depth of 8 ft (2.4 m). Excavated soil is stockpiled
above and along both sides of the trench.
2. A liner (60 mil HOPE) is installed in each trench, with
a leachate collection system placed atop it.
3. Once ready for operations, 6 months accumulation of
sludge is removed from sand drying beds and loaded
on a dump truck owned by the treatment plant.
4. The sludge is hauled the short distance to the trench-
ing area. At that location, dump trucks back into the
trenches from the open end of the trenches and
deposit the sludge in 3- to 4-ft (0.9- to 1.2-m) high piles.
248
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5. A bulldozer carefully enters the trench intermittently
to push the sludge into a 5-ft (1.5-m) high accumu-
lation.
6. After each trench is filled to completion, the bulldozer
is employed to spread cover over the 20-ft (6.1-m)
wide trench from the soil stockpiles located on either
side. The cover is spread in a 4-ft (1.2-m) thick
application to 1 ft (0.3 m) above grade.
7. The completed trench is then seeded to promote the
growth of grasses.
8. Usually settlement of the trenches will not be severe
due to the high solids content of the sludge and the
cover thickness. Once each year the bulldozer em-
ployed for landfilling operations is used to regrade
completed trenches from the previous year. These
trenches are then reseeded.
Table 14-8. Estimate of Total Annual Cost for Example Number 3
14.4.3.5 Cost Estimates
The cost estimate prepared for this operation is pre-
sented in Table 14-8. As shown, the total cost is com-
puted at $18,345 per year. Considering a sludge
quantity of 379 wet tons per year (344 Mg per year), this
equates to $48.40 per wet ton ($53.36 per Mg). This
represents a savings of $11.60 per wet ton ($12.79 per
Mg) when compared with the fee being charged by the
local MSW landfill. Accordingly, plant operators will initi-
ate the monofill disposal operation.
It should be noted that costs as low as $48.40 per wet
ton ($53.36 per Mg) cannot be achieved by most treat-
ment plants of this size. One of the reasons the cost is
low in this case is because this plant is able to monofill
6 months of sludge in 1 or 2 days. Under these circum-
stances, this facility is able to achieve economies-pf-
scale usually found only at very large monofills.
Item
Mobilization
Loader
Dozer
Trench Excavation
Covering
Regrading
Seeding
Total
Quantity
2/ea
2/ea
600 cu yd
230 cu yd
1 acre
1 acre
Unit Cost
500 /ea
500 /ea
$2.50 /cu yd
$1.50/cuyd
$10.000 /acre
$4.500 /acre
$1.000
1,000
1.500
345
10,000
4.500
18,345
249
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Chapter 15
Case Studies
These case studies were obtained from discussions
with a number of state and regional authorities respon-
sible for sludge management. They illustrate a range of
surface disposal activities being conducted throughout
the United States. Activities covered include surface
disposal of sewage sludge in a monofill, at a dedicated
disposal site, and at a dedicated beneficial use site,
in addition to sludge storage in lagoons prior to final
disposal.
15.1 Case Study 1: Surface Disposal in a
Monofill Following Freeze-Thaw
Conditioning in a Lagoon
Impoundment
Anderson Septage Lagoon
Department of Public Works
Anderson, Alaska
15.1.1 General Site Information
The City of Anderson, about 75 miles southwest of
Fairbanks, operates a lagoon impoundment for condi-
tioning domestic septage, of which it receives about
400,000 gallons annually. In 1994, the city of 700 ap-
plied to the Alaska Department of Environmental Con-
servation (ADEC) for a permit to dispose of sludge
recovered from its two storage lagoons in an onsite
monofill.
The permit application seeks an exemption from 40 CFR
Part 503 pollutant limit for sludge disposed within 25 m
of a disposal site's boundary because Anderson's dis-
posal unit is about 9 m (i.e., 30 ft) from the site's north
boundary (Figure 15-1). (If "site-specific" limits are not
set by the permitting authority, an alternative for disposal
will have to be found.) Testing has determined that the
city's sludge meets the pollution limits for solids that can
be disposed of at least 150 m from a site's nearest
boundary.
The domestic septage lagoon is located in a relatively
remote area north of a U.S. Air Force landing strip and
about 3 miles southeast of the Anderson (Figure 15-2).
Moreover, the lagoon is restricted from receiving any
hazardous or industrial waste or any municipal solid
waste. All waste received at the lagoon must meet toxic
characteristics leaching potential (TCLP) standards.
15.1.2 Site Characteristics
The Anderson lagoon is situated on a formation of gla-
cial outwash and alluvial sediment estimated to extend
to a depth of more than 20 ft, based on excavations in
a nearby gravel quarry. The sediment has been classi-
fied as poorly graded sand mixed with silt and gravel, a
geological material commonly referred to as pit run. The
site's top layer of silt loam, which was removed during
lagoon construction to take advantage of the frost-resis-
tant characteristic of the sediment, was stockpiled on
site for later use as a cover material.
Flood potential at the site has been deemed minimal,
given average annual precipitation of only 12.7 in. In-
deed, no flooding occurred in Anderson during August
of 1967 when the region's heaviest rainfall on record
(4.6 in.) caused localized flood-water problems. Al-
though Anderson did experience flooding in 1978 during
an unusually rapid thaw, it is believed that the lagoon,
which was not operating at the time, would not have
been affected.
The ground-water level at the site typically is more than
6 ft below the lagoon's percolation cell. Even during the
summer of 1992, when,ground water throughout the
region rose to an unusually high level, the water table at
the site was more than 4 ft below the percolation cell.
Further, based in part on a 1983 engineering study,
ground water flows from the lagoon impoundment in a
north by northeast direction and generally away from
Anderson (see Figure 15-2).
15.1.3 Domestic Septage Conditioning and
Disposal
15.1.3.1 Lagoon Design
The Anderson domestic septage treatment works con-
sists of a facultative cell flanked to the east and west by
active primary lagoon cells and to the south by a third
primary cell that is no longer in use. Adjoining the facul-
tative cell to the north is a percolation cell, and beyond
that the sludge disposal cell (see Figure 15-1). The
251
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no to
•f'VTt «iaoi'Intel
,
1 Y V
| !._.... ' ' "' '
SLUDGE DISPOSAL
1 • CELL
__
Y .
••v
1
1
pmr KOAO
ANDERSON SEPTAGE LAGfJON
SME PLAN
BASIS or ELCVATIOM
ASSUMED IOO.OO Of' TO*
OF AL. CAf* UOHUUCMT
SOILS NOTES
I. SOIL T£»T «T-J IYHCAL Of
SOILS FOUNO M H'J -I AND* 2.
I. KIC. RATE Or MllveuY SANO IS
S MIW./WCH.
aUVCLLY 1ANO
TEST PIT
PERCOLATION
CELL FLOOR
Figure 15-1. Anderson septage lagoon.
252
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IV
Direction Groundwitof Flow
DeiarminM by DBS EnginMn
•On-«tt» W«w Supply Stud/. 1983
Estimated Direction
of Groundwater Flow
from Anderson Lagoon
U
ANDERSON
LAGOON
OlrKtlon
17 GroundwmUr Flow
at Gravel Quarry
Figure 15-2. Site map of Anderson septage lagoon.
disposal cell (i.e., active sewage sludge unit) measures
90 x 200 ft in area and is surrounded by a 5-ft berm.
The lagoon cells measure 140 x 43 .ft (6,000 sq ft) in
area and 5.5 ft in depth to the top of the drain bed. Cell
holding capacity is 450,000 gallons of liquid and 13,000
cu ft of sludge (at a depth of 2 ft). Cells are lined with a
low-temperature arctic polyvinyl chloride (LTA PVC) ma-
terial, which provides an impermeable barrier. At the
bottom of each cell is a perforated high-density polyeth-
ylene (HOPE) pipe (10 ft on center) covered by 24 in. of
sandy gravel, allowing the cell to function as a reverse
drain field.
At the end of a storage period, liquid is siphoned off to
the facultative cell. When initial transfer of liquid is car-
ried out in the fall, a siphon alone is used because the
liquid level is relatively high. In the spring, after freeze-
thaw conditioning of the sludge has taken place and the
liquid level is lower, a pump is used to prime the siphon;
a pump manifold was constructed for this purpose.
The disposal cell is lined with pit run, which is separated
from an 8-inch layer of silt by a geomembrane material.
The gravelly layer functions as a French drain, with
rainwater and snowmelt filtering through to the silt layer.
From there the leachate drains into the percolation cell
for gradual discharge to the ground through 6 in. of silt.
15.1.3.2 Conditioning and Disposal Process
The east and west primary cells receive domestic sep-
tage in alternating years. In the sprihg, at the end of a
receiving year, liquid is siphoned off from the lagoon cell
into the facultative cell, leaving only enough residual
liquid to saturate the accumulated sludge (maximum
liquid depth is 2 ft). The following spring, after the sludge
has been conditioned through freezing and thawing,
supernatant is siphoned off into the facultative cell. The
sludge is then left to dry for about a week before it is
moved to the disposal cell—using a bulldozer and dump
truck—where it is spread onto a 6-inch layer of .silt loam.
Atypical load of dewatered sludge is spread against the
berm and across a 20- x 30-ft area in a 2- to 3-ft layer,
and the edge of the sludge pile is finished at no more
than a 2:1 slope. To "encapsulate" the material so that
pathogens and vector attraction are controlled, a 6-inch
layer of loam is spread on top of the sludge followed by
a layer of pit run. Once the cover is in place, the sludge
pile is seeded, and then reseeded in the fall.
The ground cover that results from seeding the sludge
pile contributes to leachate control through transpiration
of rain water and snowmelt, while the loam cover re-
duces infiltration of water into the disposed sludge. The
purpose of the pit-run layer/is to minimize erosional
253
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effects that can be caused by the harsh climate. None-
theless, some liquid will inevitably reach the sludge
layer. Thus, the base layer of loam and the percolation
cell are intended to slow the discharge of leachate to
the ground water to reduce concentrations of residual
pollutants.
!!•
15.1.4 Operations Factors
15.1.4.1 Sludge Characteristics
The City of Anderson has applied for a permit that would
allow disposal of sludge within 25 m of the treatment
works' north boundary with the following maximum pol-
lutant concentrations:
Arsenic
Chromium
Nickel
73 mg/dry kg
600 mg/dry kg
420 mg/dry kg
Under part 503, these concentrations are acceptable
only for sludge placed in an active sewage sludge unit
whose boundary is 150 meters from the surface disposal
site property line. The city seeks "site-specific" pollutant
limits, arguing that, despite the close proximity of the
treatment works' border, minimal opportunity exists for
humans or wildlife to come within 150 m of the disposal
cell. The area is not accessible to humans except on
foot, and it does not include any intermittent creek bot-
toms that might draw wildlife as well as hunters.
Additionally, when the city tested its sludge for
TCLP, results indicated that pollutants are below
regulatory levels.
15.1.4.2 Monitoring
In the spring, after freeze-thaw conditioning and transfer
of supernatant and prior to disposal, sludge being held
in a lagoon cell will be tested to determine if it meets
permit requirements. Sludge will be analyzed for the
parameters listed in Table 15-1. Testing will be per-
formed on a composite sample made up of three grab
samples, two collected from the base of the freeze-thaw
Table 15-1. Sludge Monitoring Parameters
tararottw | units
Antric
Chromium
Nickd
Total Sends
Pwctrt Solid*
Toul VotttI* Solids
FwalCollfonn
mg/dry kg
mg/dfy kg
mg/dry kg
mg/l
%
%
#/dry gram
method
EPA 7060
EPA 7191
EPA 6010
SM' or EPA 160.3
SM or EPA 160.3
SM or EPA 160.4
MPN. SM 9222C
bed bumper, opposite each domestic septage discharge
culvert, and a third from the area of the culvert most
used during the year (i.e., where the sludge is deepest).
After collection and mixing, the sample will be iced and
delivered to the testing lab within 1 day.
The city has no plans to monitor ground water for nitrate.
Therefore, under part 503 the city will be required to
obtain a certification by a ground-water scientist that
ground water will not be contaminated by the placement
of sewage sludge on the active sewage sludge unit.
During storage, lagoon cell liners will prevent nitrate
from leaching out of sludge. Once disposed, ammonia in
the sludge will not be able to oxidize into nitrate because
the disposal cell provides an anaerobic environment.
All records concerning disposed sludge will be retained
for 5 years.
15.1.5 Disposal Cell Capacity
The city estimates the site life of the disposal cell to be
20 years. This estimate assumes that 2,700 cu ft (100
yards) of sludge will be disposed each year. The as-
sumption takes into account the 6 in. of silt that will be
used to cover each year's load of sludge.
15.2 Case Study 2: Use of a Lagoon for
Sewage Sludge Storage Prior to
Final Disposal (Lagoon
Impoundment in Clayey Soils)
Sludge Lagoon
Domestic and Industrial Wastewater Treatment Facility
Forest, Mississippi
15.2.1 General Site Information
In 1991, the City of Forest expanded and renovated its
domestic and industrial wastewater treatment works to
increase its liquid processing capabilities. As expected,
given the increased effectiveness of improved opera-
tions, the sludge lagoon system soon approached its
solids holding capacity. Thus, the city has submitted an
application for a permit to construct two additional stor-
age lagoon cells occupying about 5 acres.
The city's sludge handling process consists of treatment
in aerobic digesters, followed by thickening and storage
in a lagoon impoundment. During storage, the sewage
sludge undergoes final disinfection, stabilization, and
thickening in anticipation of final disposal.
Since the Forest mechanical-biological wastewater
treatment works went into operation northeast of the city
in 1977, the area set aside for lagoon impoundments
has been expanded from 1.75 to 3.5 acres. The site of
the proposed additional lagoon cells is a 52-acre parcel
of open pastureland abutting two of the treatment works'
existing lagoons (Figure 15-3)."Because the parcel is
254
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bounded to the north by a free-flowing stream and to the
east and south by a similar stream, a portion of its
boundary is characterized by wetland-type soils and
vegetation; additionally, the land is considered to be in
a 100-year flood zone. Nonetheless, a Phase I environ-
mental site assessment concluded that no adverse rec-
ognized environmental conditions are present on the
property and that any potential impacts to the surround-
ing properties related to lagoon construction can be
minimized or appropriately mitigated.
75.2.2 Design Criteria
Data gathering for a geotechnical investigation of the
site included 10 soil borings (see Figure 15-3), which
found that near-surface soils in various locations con-
sisted of expansive clays containing pockets of silty
clays and sandy clays and silty clays that extend from
the ground surface to depths that ranged from about 5
to 12 ft (Table 15-2). Underlying soils included sandy
clays that extended to depths that ranged from about 13
to 16 ft as well as clays of the Yazoo Formation. Based
on these findings, the geotechnical investigation con-
cluded that the proposed lagoons could be constructed
on the naturally deposited clay soils after proper site
preparation (e.g., clearing, grubbing, and stripping of all
organics). The investigation further concluded that the
near-surface silty clay and clay soils could be used for
embankment materials—although they are not the pre-
ferred materials for this purpose—providing special de-
sign and construction measures are adopted. For
instance, the report recommended (1) the use of chemi-
cal stabilization of onsite soils to reduce plasticity and,
improve workability, and (2) the testing of each lift of fill
material to provide some assurance that adequate and
uniform densities are being obtained.
Tests to determine the permeability of in-place soils at
the site—a characteristic that is critical to the location,
design, and proper functioning of a sewage sludge la-
goon—found seepage values to be well below the maxi-
Table 15-2. Laboratory Permeability Test Results
mum allowable rate of 500 gallons per day per acre
required by state regulations.
Concerning ground-water considerations, based on two
soil borings that found free ground water at depths rang-
ing from 8 to 13 ft, the geotechnical report concluded
that problems might be encountered if construction ex-
cavations exceed depths of about 7 ft. Additionally, the
report recommended that excavations should achieve
slopes no steeper than 5 horizontal to 1 vertical to
prevent the development of slough sides.
15.2.3 Sludge Collection and Disposal
15.2.3.1 Sludge-Collection Process Steps
The treatment works' impoundment lagoons receive
sewage sludge from both industrial and domestic waste-
water treatment streams. In the industrial stream, solids
are collected in the following process steps:
• Anaerobic Lagoons: Influent raw wastewater is re-
ceived and primary removal of solids plus anaerobic
decomposition of carbonaceous biological oxygen
demand take place, with solids settling to the bottom
and accumulating over time.
• Aerated Stabilization Basins (ASBs). A pair of basins
serve as complete-mix and partial-mix lagoons. Fol-
lowing significant decomposition of sludge through
anaerobic and aerobic processes during residence in
the partial-mix lagpon, floor drains and mechanical
mixing capability allow for periodic removal of solids.
If adequate digestion has occurred in the ASB, the
solids can be transferred directly to storage lagoons.
• Sequencing Batch Reactors (SBRs). Effluent from
the ASBs is pumped to the SBRs, where the waste
undergoes an anoxic treatment promoting denitrifica-
tion followed by an aerobic treatment including nitri-
fication. The final phase of the batch treatment
process involves settling and decanting, before solids
are removed for mixing with other sludges.
Laboratory Permeability Test Results
Boring
No.
Depth
(ft)
Soil
Type
Moisture
Content
In-Place
Dry Unit
Weight
(pcf)
Liquid
Limit
Plasticity
Limit
Plasticity
Index
Percent
Passing the
No. 200
Sieve (%)
(cm/sec)
2
2
3
8
8
9
8-10
13-15
8-10
8-10
13-15
8-10
Clay
Clay
Silty Clay
Silty Clay
Sandy Clay
Silty Clay
25.1
24.8
22.7
32.4
19.4
20.4
98.1
94.8
105.5
99.7
105.9
102.5
53
69
49
48
49
46
17
19
11
15
11
13
36
50
38
33
38
33
84.8
89.2
76.8
69.5
55.1
68.3
2.98X10"1
l.OOxlO4
1.25x10*
1.27x10-*
1.08x10-*
6.50x10-*
_
255
-------
In the domestic stream, solids are collected in the fol-
lowing process steps:
• Primary Clarifiers. After screening and degritting
treatment, domestic flows are introduced to the pri-
mary clarifier, where sludge is collected by chain and
flight in rectangular basins. From there, solids are
delivered by telescoping valves to a sewage sludge
pump wetwell.
First-Stage Clarifiers. Effluent from the first-stage
aeration basins is received by 12 clarifier basins that
remove the settled solids using airlift pumping units.
A portion of the sludge is returned to first-stage aera-
Boring Locations
Scale: 1 in. = 200 ft
'SoSlesl'uigEfKjinetfs.lnc.
Figure 15-3. Site of proposed lagoon cells (Geotechnical Investigation Report),
Note: Drawing provided
by Waggoneer Engineers,
Inc.
256
-------
tion as return-activated sludge and the remainder
gravity flows to the wetwell as waste-activated sludge.
• Second-Stage Clarifiers. The second-stage aeration
basin is followed by second-stage clarifiers, from
which collected solids gravity flow to the second-
stage return sludge pump wetwell. From there, the
waste material is conveyed by lift pumps to a splitter
box that diverts a portion of the sludge to the wetwell
as waste-activated sludge.
Aerobic digesters receive all waste-activated sludge,
with the exception of sludge from the anaerobic lagoon
and from the ASB.
The two existing sludge lagoons have a total storage
capacity of 1.2 million cu ft. One of the cells reached its
capacity a number of years ago, while the other reached
its capacity only recently. Cells were loaded at a rate of 17
pounds of volatile suspended solids per 1,000 sq ft per day,
a rate that is well within the generally acceptable range.
15.2.3.2 Sludge-Disposal Alternatives
Operators of the Forest treatment works recognize that
the Part 503 regulation makes disposal of sewage
sludge an entirely different issue than storage. Given
their immediate need for additional storage capacity,
however, they are deferring any decision on disposal
alternatives for the time being.
Two possible approaches for final disposal of the treat-
ment works' sewage sludge include land application and
placement in an MSW landfill. Land application would
appear to be a less-attractive alternative because the
sludge would need to meet specific Part 503 require-
ments that include limiting pathogens and metals. In
contrast, landfilling would primarily require the sludge
to be sufficiently dewatered. Operators recognize that
disposing sewage sludges in MSW landfills, as required,
has become significantly more expensive in recent
years due to constraints on capacity. Nonetheless, a
nearby, privately owned MSW landfill that was recently
permitted might present a reasonably cost-effective dis-
posal option for the Forest treatment works.
For the present, however, operators plan to expand their
lagooning operation for storage of sludge in anticipation
of eventual disposal. During storage in the lagoons,
sewage sludge organics are gradually stabilized through
aerobic and anaerobic processes, and the stabilized
solids eventually settle to the bottom of the lagoon and
accumulate.
Clayey soils that predominate at the treatment works
site are conducive to providing a barrier of low perme-
ability soils against ground-water contamination. As-
suming that an active sewage sludge lagoon can
effectively receive digested sludge and discharge a sol-
ids-free supernatant until the average solids concentra-
tion is 8 percent for the entire lagoon volume, the rate
of waste sludge lagoon utilization will be approximately
1 acre per year for about the next 20 years.
If sewage sludge is stored on land (e.g., in a lagoon) for
longer than 2 years, the person who prepares the sew-
age sludge must demonstrate to the permitting authority
that the site is not an active sewage sludge unit. This
includes an explanation of why sewage sludge needs to
remain on the land for longer than 2 years prior to
disposal and a projection of when the sludge finally will
be used or disposed of. The surface disposal provisions
of the Part 503 rule do not apply when sewage sludge
is treated in a lagoon and treatment could be for an
indefinite period.
15.2.4 Sludge Production Projections
Based on operating data, findings from a facility study,
and the treatment works' long-term plan, operators have
estimated quantities of sewage sludge that will be pro-
duced by the year 2005 (Table 15-3). For example,
operators project that sewage sludge produced by ASBs
for removal to lagoons will reach 4,097 pounds per day;
this amount is calculated to decompose to about 2,538
pounds per day. Similarly, sludge produced by SRBs is
expected to reach about 1,738 pounds per day.
In contrast, sewage sludge produced from domestic
flows is expected to increase at the moderate annual
rate of 1.5 percent, based on current population trends.
15.3 Case Study 3: Dedicated Surface
Disposal in a Dry-Weather Climate
Solids Handling and Disposal Facility
Domestic Wastewater Treatment Facility
Colorado Springs, Colorado
15.3.1 General Site Information
The City of Colorado Springs operates processes for
managing and disposing of sewage sludge generated at
its POTW, which treats average flows of over 34 million
gallons per day. Along with an anaerobic digestion com-
plex for stabilization and an expanse of facultative
sludge basins for additional long-term treatment of sta-
bilized material, sewage sludge is disposed of on a
dedicated surface disposal site.
The surface disposal site is located 18 miles south of
the POTW at the city's Hanna Ranch property, which
also is used for disposal of ash from the city's Ray Nixon
Power Plant. A blend of primary and secondary sludge
is conveyed from the POTW to Hanna Ranch via a
pipeline—one of the longest pipelines in the country
used to transport sewage sludge.
Minimal residential and commercial development has
taken place near the Hanna Ranch site due to a limited
257
-------
Table 15-3. Sewage Sludge Projections
Solids
Category
ASB FSS (#/day)
ASB nVSS (#/day)
ASB VSS (#/day)
ASB TOTALS
SBR FSS (#/day)
SBR nVSS (#/day)
SBR VSS (#/day)
SBR TOTALS
DOM. PLANT FSS (#/day)
DOM PLANT nVSS (#/day)
DOM. PLANT VSS (#/day)
DOM. TOTALS
TOTAL FSS (*/day)
TOTAL nVSS (*/day)
TOTAL VSS (#/day)
TOTAL SLUDGE SOUDS
1995
Digester
Influent
_ „
—
—
—
481
695
561
1.737
170
320
361
851
651
1,015
922
2.588
Lagoon
Influent
578
817
1,391
2,786
481
626
413
1,520
170
204
238
612
1,229
1,647
2,042
4,918
Final
Disposal
578
817
696
2.091
481
626
306
1.413
170
204
95
469
1,229
1,647
1,097
3,973
2005
Digester
Influent
—
—
757
1,095
923
2,775
197
371
419
987
955
1,466
1,342
3.762
Lagoon
Influent
730
1,021
2,346
4,097
757
985
641
2,383
197
237
276
710
1,684
2,243
3,263
7.190
Final
Disposal
730
1,021
782
2,533
757
985
475
2,217
197
237
110
544
1,684
2.243
1,367
5.294
drinking water supply and the proximity of a military
training range to the west. Given its relatively remote
character, a portion of the ranch is set aside as a wildlife
area, which is managed cooperatively by the state's
Division of Wildlife and city utilities. Beyond merely
monitoring the compatibility of operations with area
wildlife, site managers have tested a habitat enhance-
ment practice that involves growing feed crops within
the disposal site for incidental grazing by antelope and
waterfowl.
The soils at the Hanna Ranch site consist of verdos
alluvium, piney creek alluvium, and a weather Pieere
shale with low to very low permeabilities. Monthly aver-
age temperatures at the site range from 29°F to 71 °F.
Public access to the surface disposal site is restricted
by a fence that surrounds the Hanna Ranch and a
uniformed security guard stationed 24 hours a day at the
north entrance. Visitors are allowed limited access to the
ranch for hunting and wildlife observation through a 3-ft
opening in the fence at the site's south entrance, which
is about 1.5 miles east of the active disposal units.
The site meets all of the Part 503 requirements. Char-
acterization/management issues addressed in the site's
state/county Certification of Designation include:
• A survey by the state's Division of Wildlife found that
the disposal operations do not adversely affect a
threatened or endangered species.
• Although no wetlands have been delineated in ac-
cordance with U.S. EPA or Corps of Engineers pro-
cedures, active sewage sludge units appear to be
adjacent to one small (0.1 to 0.2 acres), isolated
wetland in a creek drainage. Although disturbance of
this wetland would be permitted under the nationwide
permit for headwaters and isolated areas, current ac-
tivities do no disturb the wetland.
• A site ground-water plan was recently rewritten by a
qualified ground-water scientist to comply with 40
CFR Part 503. The plan includes 2 years of quarterly
monitoring to determine ambient conditions, as re-
quired by the state, with a focus on total inorganic
nitrogen and organic carbon concentrations.
• Modifications have been made to small sections of
the active sewage sludge unit that were estimated to
be special flood hazard areas that would be inun-
dated by a 100-year flood. Runoff from a creek drain-
age (up to a 1,000-year flood) is contained for
evaporation at a retention dam.
• A review of area geology confirmed that the surface
disposal site is not in a seismic impact zone or in an
unstable area.
258
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15.3.2 Surface Disposal Approach
15.3.2.1 Process Description
At the solids handling and disposal facility, sewage
sludge is gas mixed in four 1.5-million gallon anaerobic
digesters. Once stabilized, the waste material is
pumped to 30 acres of facultative sludge basins (FSBs,
known in other states as facultative sludge lagoons)
where it is treated under a 5-ft water cap for at least 3
years. After the digested sludge is removed from the
bottom of the basins using a dredge equipped with a
diesel-driven pump, they are conveyed through a float-
ing, flexible pipe to a wet well in the control building. The
sludge then is pumped from the wet well to a riser at
each dedicated surface disposal (DSD) unit. From the
riser, the sludge is loaded into the holding tank of a
Terragator, a sludge dispersal vehicle equipped with
flotation tires, and injected into the subsurface of the
DSD units. The four DSD units at Hanna Ranch (Figure
15-4) total 180 acres.
The primary method of liquid disposal is through evapo-
ration. Excess liquid from the facultative basins is
pumped to supernatant lagoons for additional treatment,
evaporation, and disposal.
In 1993, over 9,000 metric tons of sludge was disposed
by subsurface injection at an average rate of 113 metric
tons per hectare (124.3 tons per 2.5 acres). Disposal
operations are limited to seasons when both the soil in
the DSD units and the surface of the FSBs are not
frozen. In 1993, disposal operations were conducted
from March 16 to November 11.
15.3.2.2 Character of Sewage Sludge
The sludge produced at the POTW is of high quality.
When surface disposed, however, the boundary of DSD
units (i.e., active sewage sludge units) must be more
than 100 m from the property line of the surface disposal
site because of slightly elevated chromium concentra-
tions (Table 15-4).
Steps taken to control pathogens and reduce vector
attraction in the sewage sludge make the sludge appro-
priate for surface disposal. Relatively high concentra-
tions of helminth ova, however, have prevented the
sludge from meeting Class A criteria without significant
additional treatment. Because the sludge is injected into
the surface, further pathogen and vector reduction con-
trols are not required by Part 503. The City of Colorado
Springs has elected, however, to treat its sludge further.
Pathogen reduction is carried, out using high-rate an-
aerobic digestion to meet the requirements of a process
to significantly reduce pathogens (PSRP). The process
involves the anaerobic treatment of sludge for a specific
mean cell residence time (MCRT) of about 20 days at a
temperature of 96.8°F (36°C). Raw solids are fed
DIGESTER'- CO
ENERGY 'RECOVERY BUILDING
' '
Figure 15-4. Topographic map of Hanna Ranch area.
259
-------
Table 15-4. 1993 Sewage Sludge Monitoring Results
1093
0*te
March 18
Jtrch 23
Kareh 30
iprta
\pl» >3 »
*pr»20
*prM27
.lay 4
<«y 18
Junal
tunes
June IS
tana 22
June 20
July 2O
July 27
Mig 17
4ug24
*ug3t
3«p14
Up 21
3ep2S
Oct2B
ov2
Anenfc
. "0*0
22
<2 0
<2,0
<2,0
<2,0
2B
Chromkjrn
mg/kg
290
280
310
210
mg/kg
192
Z.
Mercury
mg/kg
4.31
Moly
mg/kg
15
Nickel
mg/kg
190
190
210
Selenium
mg/kg
20
Zinc
mg/kg
2,070
Conform '
MPN/g
430,000
230,000
• 150,000
40.000
40,000
65,600
2.200
5,900
800 '
400
1,100
800
300
500
800
640
2,020
800
130
50
260
110
210
130
Helminth, »/4 g
Observed * Viable
2,000
0,000
1.200
2,000
3,200
4,400
2,400
2,400
S34
Salmonella
MPN/g
<0.2
Enleitc
PFU/4 g
-------
Table 15-5. PSRP Minimum Temperatures for Anaerobic
Digestion
PSRP Minimum Temperatures for
Anaerobic Digestion
Mean Cell
Residence Time
(days)
15
16
17
18
19
20
21
22
23
24
25
Minimum
Temperature
(°C/°F)
35/95
35/95
34/93
34/93
34/93
33/91
33/91
33/91
32/90
32/90
32/90
solids reduction is a function of temperature and MCRT
in the anaerobic digestion system. Thus, the same op-
erational considerations (discussed above) for pathogen
control ensure vector attraction reduction. In 1993, for
example, average volatile solids reduction at the Hanna
Ranch facility was 59 percent, well above the standard
of 38 percent.
15.3.3 Operation and Maintenance
The surface disposal site is attended 10 hours a day by
a crew of nine. It is linked by computer and microwave
communications to the POTW in Colorado Springs to
enable remote monitoring when operators are not on site.
15.4 Case Study 4: Dedicated Surface
Disposal in a Temperate Climate
Sludge Surface Disposal Site
Metro Sanitary District
Springfield, Illinois
15.4.1 General Site Information
The Metro Sanitary District in Springfield, Illinois, has
operated two sites for treatment and subsequent sur-
face disposal of sewage sludge since 1973. At the dis-
trict's Spring Creek surface disposal site, located north
of the city in the vicinity of Capital Airport and the state
fairgrounds (Figure 15-5), sludge is disposed on 80
acres of land following anaerobic digestion. Sludge re-
ceived at the smaller, Sugar Creek surface disposal site,
which is directly east of the city and roughly between
two interchanges of Interstate 55 (Figure 15-6), is sub-
jected to aerobic digestion before disposal on 30 acres.
In most years, livestock feed has been grown on a
portion of one or both sites. Sludge is disposed only on
the areas that are not cropped, which are alternated
each year. Additionally, broadleaf weed killer is applied
annually at both sites. The sites must meet the require-
ments for pathogen control and vector attraction control,
including site restrictions, under the Part 503 rule.
Although the district has grown corn exclusively since
the late 1980s, other feed crops have included alfalfa,
sorghum, soybeans, and winter wheat. The disposal
sites have been plowed and disked annually, except at
the Sugar Creek surface disposal site between 1978
and 1987 when the district cultivated bluegrass and
attempted to enter the sod market. As a result of the
more stringent limits on nitrate in the Part 503 regulation,
the district is switching at both sites from corn to canary
grass, a hay crop that has higher nitrate requirements.
Samples from monitoring wells at the sites have shown
that nitrate levels in ground water tend to be elevated at
certain times of the year and during specific weather
patterns. As a result, along with planning to change the
feed crop at the site, the district has applied to the state
environmental agency and the U.S. EPA for reclassifica-
tion of the sites' ground water as Class II water. The
district has assured authorities that it will be able to meet
applicable state and federal requirements for the protec-
tion of ground water.
As a result of the pathogen control and vector attraction
reduction requirements in Part 503, the district also
plans to upgrade its aerobic treatment process at the
Sugar Creek site (as described in Section 15.4.3.2).
15.4.2 Design Criteria
The western section of the Spring Creek surface disposal
site, which began receiving sludge for disposal in Octo-
ber 1973, meets applicable design criteria for sludge
disposal based on site features that include being:
• Situated 200 feet from any water well and above the
10-year flood plain.
• Constructed with a slope of less than 5 percent (ex-
cept for a small section of the interior portion of the
site).
• Bordered by a shallow berm and a restricted asphalt
roadway to contain runoff.
• Characterized by a tight clay soil.
Important design features of the Spring Creek site's east-
ern section, which was put into service in March 1980,
include being:
261
-------
)<•/
Figure 15-5. Spring Creek disposal site.
262
-------
Figure 15-6. Sugar Creek disposal site.
263
-------
• Situated 150 feet from any water well and 200 feet
from any surface water.
• Constructed with a slope of less than 5 percent.
• Bordered by a berm (necessary because this section
of the site is in a flood plain).
• Characterized by a sandy soil.
The district's Sugar Creek surface disposal site, which
has been in use since October 1973, meets design
criteria for sludge disposal based on site features that
include being:
• Situated 150 feet from any water well and 200 feet
from any surface water.
• Constructed with a slope of less than 5 percent.
• Characterized by a silty loam soil.
The site includes a 10-acre lagoon to catch runoff in the
event of flooding. In the 20-plus years of operation,
however, the site has not been subjected to a major
flooding event.
Additionally, both the Spring Creek and Sugar Creek
surface disposal sites are 200 feet from either an occu-
pied dwelling or a public roadway.
15.4.3 Treatment and Surface Disposal
Approach
15.4.3.1 Spring Creek Surface Disposal Site
Process Description. The primary and waste-activated
sludge received at the Spring Creek surface disposal
site undergoes primary anaerobic digestion, which in-
volves heating and mixing of the material, followed by
treatment in secondary digesters. By operating three
primary digesters and six secondary units, on average
about 28,000 gallons of sludge are processed each day.
Operators also have attempted thickening waste-acti-
vated sludge in one of the six secondary digesters; one
of the approaches included the use of a gravity-belt
thickener.
Following the digestion process, the sludge is either (1)
held in uncovered drying beds and spread on the sur-
face disposal site after dewatering, or (2) it is sprayed
onto the disposal site using fixed risers spaced 150 to
200 feet apart.
When spraying, pairs of risers operate in sequence
dispersing 40,000 gallons of sludge with 50 psi of pres-
sure across the area within their range. The edge of the
spray pattern for the site's 92 risers is set at 110 to 180
feet from the surface of nearby Spring Creek. To mini-
mize leaching of sludge into ground water, the entire
disposal site is underdrained 6 to 9 feet below ground
with 4- and 6-inch perforated pipe that is laterally spaced
at 50 to 75 feet. Underdrains and forcemains are flushed
after spraying, and collected sludge water is pumped to
the effluent end of the primary treatment process.
The surface disposal site's 55,000 square feet of drying
beds generally are used only during the colder months
of winter, when spraying cannot be carried out, or when
the spraying system is shut down for maintenance.
Sludge placed in the beds in winter is allowed to dry until
fall of that year, when it is hauled to the eastern section
of the disposal site for spreading. The drying beds re-
ceived 120,000 gallons of sludge in 1983 and almost
600,000 gallons in 1987, the only years to date when
the beds were used.
Sludge residuals collected in the bottom of the site's
secondary digesters are periodically pumped, using
centrifugal pumps, to one of the disposal sites or is
drawn by gravity to the drying beds. Water drained from
the drying beds is pumped to the effluent end of the
primary treatment works.
Character of Sewage Sludge. Sludge produced at the
Spring Creek surface disposal site generally has a total
solids content of 4.7 percent, volatile content of 41.2
percent, and a volatile acids concentration of 260 mg/L.
Annual loading rates at the disposal site for nitrogen,
phosphorus, and various metals are listed in Table 15-6.
15.4.3.2 Sugar Creek Surface Disposal Site
Process Description. The waste-activated sludge and
floating scum materials (from secondary clarifiers) re-
ceived at the Sugar Creek surface disposal site undergo
staged treatment in a series of three aerobic digestion
units. By operating units with a combined capacity of
over 222,000 cubic feet (i.e., about 74,000 cubic feet
each), on averages about 25,000 gallons of sludge can
be processed per day. On average 106,000 gallons of
sludge (with a suspended solids content of about 8,000
mg/L) is sent to the digesters daily.
Each day, or as needed, the digestion system's
airflow is shut down so that supernatant can be drawn
into contact aeration tanks, making room for sludge
inputs. Occasionally, surface scum is also removed and
disposed along with other sludge. During the winter,
Table 15-6. Annual Pollutant Loading Rates at the Spring
Creek Facility
Parameter
Organic Nitrogen
Phosphorus
Lead
Zinc
Copper
Nickel
Cadmium
Manganese
«":.' ££S
io.a 22.7
41-3 87..0
24.8 52.3
o?i8 o^
28.1 59.3
?T°a5?n¥ J»ct°r - 0.002 x 14.1 - o;0282 (He»t)J
[Loading Factor - 0.002 x 29.7 - 0.0594 (Bast)]
Note: Average over 1983-1992.
264
-------
sludge or scum is occasionally added to digestion tanks
to control temperatures and ice formation.
Every 5 or 10 days, when the solids levels in the system
reach about 15,000 to 25,000 mg/Lor clear supernatant
is no longer present, sludge is removed from the final
digestion unit. The sludge material is removed in incre-
ments of 205,000 gallons and pumped, using centrifugal
pumps, to the active sewage sludge unit. At the unit, the
sludge is sprayed onto the surface from 30 risers each
spaced about 200 feet apart. The spray system func-
tions and is configured much like the system used at the
Spring Creek site; it includes an underdrain system, and
flushed sludge water is recycled to the treatment tanks.
At this site, however, three risers operate in sequence,
spraying 205,000 gallons of sludge within their range.
The site also includes two drying beds, covering 2,500
square feet, which to date operators have not needed to
use in the sludge treatment process. Operators are
considering the addition of a lime stabilization stage,
however, as a final treatment step. Stabilization may be
required during the winter months, when biofogicaf ac-
tivity in the aerobic digesters slows, to meet Part 503
requirements for pathogen control and vector attraction
reduction.
Character of Sewage Sludge. Sludge treated at the
Sugar Creek site generally has a total solids content of
1.9 percent and volatile content of 50 percent. Annual
loading rates at the disposal site for nitrogen, phospho-
rus, and various metals are listed in Table 15-7.
Table 15-7. Annual Pollutant Loading Rates at the Sugar
Creek Facility
Parameter
Organic Nitrogen
Phosphorus
L«ad
Zinc
Cpppar
Nickel
Cadmium
Manganese
annual Loading - lb»/»cr«
1957.0
969.4
21.2
46.2
21.7
1.9
0.43
83,2
(loading Factor - 0.002 x 24.3 - 0.0486)
Note: Average over 1983-1992.
265
-------
-------
APPENDIX A
Permit Application
Permits that are issued to publicly owned treatment
works (POTWs) must include standards for sewage
sludge use or disposal. In addition, EPA may issue
sewage sludge permits to other "treatment works treat-
ing domestic sewage" (TWTDS) (i.e., other persons that
generate, change the quality of, or dispose of sewage
sludge).
The EPA's sewage sludge permit program regulations
establish a framework for permitting sewage sludge use
or disposal. The regulations require submission of a
permit application that provides the permitting authority
with sufficient information to issue an appropriate permit.
A permit application must include information on the
treatment work's identity, location, and regulatory status,
as well as information on the quality, quantity, and ulti-
mate use or disposal of the sewage sludge generated
at the treatment works.
Because the sewage sludge permitting regulations were
promulgated several years before the Part 503 stand-
ards, they describe the required application information
in broad, almost generic terms. Currently, EPA is devel-
oping application forms and the Agency is planning to
revise the permit application regulations to reflect spe-
cifically the Part 503 standards and to enable permit
writers to tailor permit requirements to specific use or
disposal practices.
The deadlines for submitting permit applications were
revised in 1993 and are as follows:
• Applicants requiring site-specific pollutant limits in
their permits (e.g., sewage sludge incinerators) and
applicants requesting site-specific limits (e.g., some
surface disposal sites) were required to submit appli-
cations by August 18, 1993.
• All other applicants with National Pollutant Discharge
Elimination System (NPDES) permits are required to
submit sewage sludge permit applications at the time
of their next NPDES permit renewals.
• Sludge-only (non-NPDES) facilities that are not apply-
ing for site-specific limits, and not otherwise required to
submit a full permit application, had to submit limited
screening information by February 19, 1994.
The permit application information that must be submit-
ted depends on the type of treatment works and which
sewage sludge disposal practices are employed by the
treatment works. Questions on permit applications should
be directed to the appropriate State and EPA Regional
Sewage Sludge Contacts listed in Appendix B.
Sludge-Only Facilities
The limited screening information submitted by a
sludge-only facility typically will include the following:
• Facility name, contact person, mailing address,
phone number, and location.
• Name and address of owner and/or operator.
• An indication of whether the facility is a POTW, pri-
vately owned treatment works, federally owned treat-
ment works, blending or treatment operation, surface
disposal site, or sewage sludge incinerator.
• The amount of sewage sludge generated and re-
ceived, treated, and used or disposed.
• Available data on pollutant concentrations in the sew-
age sludge.
• Treatment to reduce pathogens and vector attraction
properties of the sewage sludge.
• Identification of other persons receiving the sewage
sludge for further processing or for use or disposal.
• Information on sites where the sewage sludge are
used or disposed.
Treatment Works Submitting Full Permit
Applications
A full permit application is much more comprehensive
than the limited screening information described above
for sludge-only facilities. A full permit application typi-
cally will include the following information:
General Information
• Name, contact person, mailing address, phone num-
ber, and location.
• Name and address of owner and/or operator.
267
-------
• An indication of whether the facility is a POTW, pri-
vately owned treatment works, federally owned treat-
ment works, blending or treatment operation, surface
disposal site, or sewage sludge incinerator.
• Whether the facility is a Class I sludge management
facility (i.e., a pretreatment POTW or another facility
designated Class I by the permitting authority).
• The NPDES permit number (if any) and the number
and type of any relevant Federal, State, or local en-
vironmental permits or construction approvals applied
for or received.
• Whether any sewage sludge use or disposal occurs
on Native American lands.
• A topographic map showing sewage sludge use or
disposal sites and water bodies 1 mile beyond the
property boundary and drinking water wells 1/4 mile
beyond the property boundary.
• Results of hazardous waste testing for the sewage
sludge, if any.
• Data on pollutant concentrations in the sewage sludge.
Information on Generation of Sewage Sludge
or Preparation of a Material From Sewage
Sludge
• The amount of sewage sludge generated.
• If sewage sludge is received from off site, the amount
received, the name and address of person from
whom the sewage sludge was received, and any
treatment the sewage sludge have received.
• Description of any treatment to reduce pathogens and
vector attraction properties of the sewage sludge.
• Description of any bagging and distribution activities
for the sewage sludge.
• If sewage sludge is provided to another person for
further treatment, the amount provided, the name and
address of the receiving person, and a description of
any subsequent treatment.
Information on Surface Disposal of Sewage
Sludge (If Sewage Sludge Is Placed on a
Surface Disposal Site)
• The amount of sewage sludge placed on surface
disposal sites.
• The name, address, contact person, and permit num-
ber^) for each surface disposal site, regardless of
whether the applicant is the owner/operator.
In addition, the following inform