&EPA
United States
Environmental Protection
Agency
Office of Water
Regulations and Standards
Washington, DC 20460
Water
TECHNICAL SUPPORT
DOCUMENT
Landfilling of Sewage Sludge
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PREFACE
Section 405(d) of the Clean Water Act requires the U.S. Environmental
Protection Agency (EPA) to develop and issue regulations that identify:
Uses for sludge, including various means of disposal
Factors, including costs, which must be considered when determining the
measures and practices applicable to each use or disposal method
Pollutant concentrations that interfere with each use or disposal
method
To comply with this statutory mandate, EPA has embarked on a program to
develop five major technical regulations for the following areas: land
application/distribution and marketing; monofilling; surface disposal;
incineration; and reduction of pathogens and vector attraction. EPA also has
proposed regulations governing the establishment of State sludge management
programs, which will implement both existing and future criteria (40 CFR 501).
\ The primary goal of the proposed monofill regulation is to protect human
health and the environment. Included in this proposed regulation are
provisions to protect air and groundwater quality from the deleterious effects
that potentially may occur due to sludge monofilling. This document provides
the technical background and justification for the provisions contained in
Subpart D of the proposed regulation. [
Public comment on the technical adequacy and scientific validity of this
document as well as on the requirements contained in the proposed regulation
should be submitted during the public comment period. Any questions related
to this document may be directed to:
Norma K. Whetzel
U.S. Environmental Protection Agency
Wastewater Solids Criteria Branch
Washington, DC 20460
202-475-7313
Martha Prothro, Acting Director
Office of Water Regulations and Standards
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TABLE OF CONTENTS
Page
LIST OF TABLES vii
LIST OF FIGURES ix
LIST OF UNITS AND ACRONYMS xi
L. TECHNOLOGY AND PROCESSES 1-1
1.1 Monofills 1-2
1.2 Leachate 1-4
1.3 Surface Water Contaminant 1-4
1.4 Gas Control 1-6
1.5 Land Requirements 1-6
1.6 Storage 1 7
1.7 Good Practices 1-8
1.8 Sludge Quality 1-8
2. RISK ASSESSMENT METHODOLOGY 2-1
2.1 Introduction 2-1
2.2 Identification of Pathways of Exposure and Health and 2-1
Environmental Criteria
2.2.1 Pathways of Exposure 2-2
2.2.2 Human Health and Environmental Impact Criteria 2-6
2.3 Overview of SLUDGEMAN 2-7
2.4 Description of the Groundwater Components of the 2-10
SLUDGEMAN Model
2.4.1 Pulse-time Calculation (SATM1 and SLUGMAN) 2-10
2.4.2 TJnsaturated Zone Model (CHAIN) 2-12
2.4.3 Saturated Zone Model (AT123D) 2-18
2.4.4 Integrating the Unsaturated and Saturated Zone 2-19
Models
2.5 Description of the Vapor Pathway Components of the 2-20
SLUDGEMAN Model
2.6 Use of SLUDGEMAN to Establish Criteria for Pollutants 2-22
in Sludges
2.6.1 Groundwater Pathway Calculation 2-22
2.6.2 Vapor Pathway Calculation 2-25
2.7 Science Advisory Board Review 2-25
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TABLE OF CONTENTS (Continued)
Page
3. DATABASE FOR THE RISK MODEL 3-1
3.1 Model Sludge Parameters 3-1
3.1.1 Sludge Moisture Content 3-1
3.1.2 Sludge Storage Capacity 3-3
3.1.3 Sludge Density 3-3
3.1.4 Specific Gravity 3-5
3.2 General Hydrologic Parameters 3-7
3.2.1 Net Recharge 3-7
3.2.2 Depth to Ground Water 3-8
3.2.3 Aquifer Thickness 3-9
3.2.4 Groundwater pH 3-9
3.2.5 Groundwater Eh 3-10
3.3 Unsaturated Zone Parameters 3-10
3.3.1 Unsaturated Zone Soil Type 3-10
3.3.2 Unsaturated Zone Thickness 3-11
3.3.3 Slope of the Soil Moisture Retention Curve 3-12
3.3.4 Effective Porosity of the Unsaturated Zone 3-12
3.3.5 Bulk Density in the Unsaturated Zone 3-14
3.3.6 Saturated Soil Hydraulic Conductivity 3-15
3.4 Saturated Zone Parameters 3-15
3.4.1 Saturated Zone Soil Type 3-16
3.4.2 Effective Porosity in the Saturated Zone 3-16
3.4.3 Hydraulic Gradient in the Saturated Zone 3-18
3.4.4 Bulk Density in the Saturated Zone 3-18
3.4.5 Saturated Zone Hydraulic Conductivity 3-18
3.5 Surface Parameters 3-20
3.5.1 Landfill Site Geometry 3-20
3.5.2 Distance to the Property Boundary 3-20
3.5.3 Surface Wind Velocity 3-22
3.5.4 Air Temperature 3-22
3.5.5 Air-filled Porosity of Cover Soil 3-22
3.5.6 Total Porosity of Cover Soil 3-22
3.5.7 Cover Thickness 3-23
3.6 Chemical-specific Parameters 3-23
3.6.1 Concentrations of Contaminants in Sludge 3-23
3.6.2 Concentrations of Contaminants in Sludge 3-23
Leachate
3.6.3 Distribution Coefficient 3-26
3.6.4 Saturated and Unsaturated Zone Decay Rate 3-28
3.6.5 Background Concentrations of Contaminants 3-28
3.6.6 Health Effects Levels 3-31
3.6.7 Molecular Weight 3-34
3.6.8 Henry's Law Constants 3-34
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TABLE OF CONTENTS (Continued)
Page
4. SENSITIVITY ANALYSIS 4-1
4.1 Effect of Soil Depth and Carbon Content 4-2
4.1.1 Results for Class 1 Aquifers 4-4
4.1.2 Results for Class 2 Aquifers 4-6
4.2 Effect of Recharge Rate 4-8
4.3 Effect of Groundwater Velocity 4-9
4.4 Effect of Aquifer Thickness 4-11
4.5 Effect of Eh and pH 4-12
4.6 Effect of Sludge Moisture Content 4-13
5. POLLUTANT LIMITS 5-1
6. GENERAL SITING REQUIREMENTS 6-1
6.1 Airport Siting Requirements 6-1
6.1.1 Impacts of Siting Facilities near Airports 6-1
6.1.2 Regulatory Requirement for Siting Monofills 6-4
near Airports
6.2 Floodplain Siting Requirements 6-5
6.2.1 Types of Floods Occurring in 100-yr Floodplains 6-5
6.2.2 The History of the 100-yr Floodplain as an EPA 6-7
Regulatory Standard
6.2.3 Impacts of Siting Facilities in Floodplains 6-9
6.2.4 Preventive Measures and Emergency Responses to 6-12
Flooding of Facilities
6.2.5 Case Studies 6-14
6.2.6 Regulatory Requirement for Siting Monofills in 6-14
Floodplains
6.3 Wetlands Siting Requirements 6-17
6.3.1 Impacts of Siting Facilities in Wetlands 6-19
6.3.2 Current Federal Protection Measures 6-20
6.3.3 Regulatory Requirement for Siting Monofills in 6-21
Wetlands
6.4 Fault Area Siting Requirements 6-22
6.4.1 Impacts of Siting Facilities in Fault Areas 6-24
6.4.2 Regulatory Requirement for Siting Monofills in 6-25
Fault Areas
6.5 Seismic Impact Zone 6-25
6.5.1 Impacts of Siting Facilities in Seismic 6-26
Impact Areas
6.5.2 Regulatory Requirement for Siting Monofills 6-28
in Seismic Impact Areas
6.5.3 Methods for Determining Seismic Risk 6-29
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TABLE OF CONTENTS (Continued)
Page
r o A
6.6 Siting Requirements for Unstable Areas
6.6.1 Types of Unstable Areas
6.6.2 Impacts of Siting Facilities in Unstable Areas b-J/
6.6.3 Alternatives
6.6.4 Regulatory Requirement for Siting Monofills in 6-jjy
Unstable Areas
7. MANAGEMENT PRACTICES 7~1
7.1 Landfill Cover Requirements I-\.
7.1.1 Landfill Cover ~>'-l
7.1.2 Depth of Cover 7"2
7.1.3 Characteristics of Cover Material 7-2
7.2 Disease Vector Control Requirements 7-3
7.3 Requirements for Control of Explosive Gases 7-4
7.4 Access Control Requirements 7-6
7.5 Runon/Runoff Control Requirements 7-7
7.5.1 Runon 7-8
7.5.2 Runoff 7-8
8. REFERENCES 8-1
APPENDIX A PARTITIONING OF POLLUTANTS BETWEEN SLUDGE SOLIDS
AND WATER
APPENDIX B SENSITIVITY ANALYSIS ON SELECTED MODEL PARAMETERS
APPENDIX C APPROVED METHODS FOR SITE-SPECIFIC PARAMETERS
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LIST OF TABLES
Table No. Title Page
Table 1-1 Range of Constituent Concentrations in Leachate from Sludge 1-5
Monofills
Table 3-1 Summary of Model Parameters and Assigned Values 3-2
Table 3-2 Typical Sludge Solids Content by Landfill Type 3-4
Table 3-3 Typical Values for the Slope of the Soil Moisture Retention 3-13
Curve by Soil Type
Table 3-4 Effective Porosities for General Hydrogeologic 3-17
Classifications
Table 3-5 Landfill Site Geometry 3-21
Table 3-6 Concentrations of Contaminants in Sludge 3-24
Table 3-7 Concentrations of Contaminants in Sludge Leachate 3-25
Table 3-8 Distribution Coefficients 3-27
Table 3-9 Saturated and Unsaturated Zone Decay Rates 3-29
Table 3-10 Background Concentrations of Contaminants 3-30
Table 3-11 Health Effects Levels 3-32
Table 3-12 Standard Molecular Weights for Modeled Pollutants 3-35
Table 3-13 Henry's Law Constants for Selected Contaminants 3-36
Table 4-1 Input Parameters for the Baseline Case 4-3
Table 4-2 Effect of Soil Depth and Organic Carbon Content on Maximum 4-5
Allowable Pollutant Concentrations for Class I Aquifers
Table 4-3 Effect of Soil Depth and Organic Carbon Content on Maximum 4-7
Allowable Pollutant Concentrations for Class II Aquifers
-Vll-
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LIST OF TABLES (Continued)
Table No. Title Page
Table 4-4 Effect of Groundwater Velocity on Maximum Allowable Sludge 4-10
Concentrations
Table 5-1 Maximum Sewage Sludge Concentration 5-3
Table 6-1 Distribution of Bird Strikes by Aircraft Part Struck for 6-3
U.S. Military Aviation
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LIST OF FIGURES
Figure No. Title Page
Figure 2-1 Routes to Human Exposure from Landfilling Sludge 2-3
Figure 2-2 Contaminant Migration Pathways for Narrow Trench 2-4
Landfills
Figure 2-3 Contaminant Migration Pathways for Pit or Wide 2-5
Trench Landfills
Figure 5-1 Sewage Sludge Monofill 5-5
Figure 6-1 Existing Flooding Problems in the United States 6-6
-IX
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LIST OF UNITS AND ACRONYMS
ac acre
BEHP bis(2-ethylhexyl)phthalate
bw body weight
CFR Code of Federal Regulations
CWA Clean Water Act
ODD Bis l,l-(4-chlorophenyl)-2,2-dichloroethane
DDE Bis l,l-(4-chlorophenyl)-2,2-dichloroethylene
DDT Bis 1,1-(4-chlorophenyl)-2,2,2-trichloroethylene
Eh oxidation-reduction potential
EO Executive Order
EPA U.S. Environmental Protection Agency
FAA Federal Aviation Administration
FR Federal Register
ft feet
ha hectare
HEL health effects level
hr hour
kg kilogram
kd distribution coefficient
KO,. organic carbon partition coefficient
K^ octanol-water partition coefficient
K^ saturated hydraulic conductivity
L liter
L<. leachate concentration
Ly limiting leachate concentration
LEL lower explosive level
In natural logarithm
m meter
m2 square meter
m3 cubic meter
MCL maximum contaminant level
MEI most exposed individual
MF modifying factor
mg milligram
mL milliliter
mm millimeter
mph miles per hour
MPN most probable number
mt metric ton
mv millivolt
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LIST OF UNITS AND ACRONYMS (Continued)
NOAEL no-observed-adverse-effects level
OHEA Office of Health and Environmental Assessment
ORD Office of Research and Development
OWRS Office of Water Regulations and Standards
PCB polychlorinated biphenyl
pH relative hydrogen ion concentration
RCRA Resource Conservation and Recovery Act
RfD Risk Reference Dose
SAB Science Advisory Board
Sc sludge concentration
Sd limiting sludge concentration
su standard units
t^ environmental half-life
tc contaminant travel time
TCE trichloroethylene
TKN total Kjeldahl nitrogen
TOT time of travel
TW water travel time
ug microgram
UF uncertainty factor
WRC Water Resources Council
yr year
-xix
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SECTION ONE
TECHNOLOGY AND PROCESSES
This section provides an overview of landfill technology and practices.
It describes good management practices, but does not refer to specific
regulatory requirements.
Landfilling is a sludge disposal method in which sludge is deposited in a
dedicated area, alone or with solid waste, and buried beneath a soil cover
Landfilling is primarily a disposal method, with no attempt to recover
nutrients and only occasional attempts to recover energy from the sludge.
Currently, about 41% of the municipal wastewater sludge generated in the
United States is landfilled.
To a certain extent landfilling, like land application, is an extension of
sludge treatment. However, there is an important difference. When sludge is
landfilled, insufficient oxygen is available to support aerobic degradation,
such as occurs during land application and composting. Instead, anaerobic
degradation occurs. Anaerobic conditions degrade the sludge more slowly and
less completely than aerobic processes. In addition, anaerobic degradation
produces methane gas that must be properly vented or collected from the
landfill.
Two major types of landfilling are currently practiced: sludge-only
disposal (monofill), in which sludge is buried, usually in trenches, and co-
disposal, in which sludge is disposed with other solid waste at a municipal
solid waste landfill. Approximately 1.3% of the sewage sludge generated in
the United States is disposed in monofills. Because the proposed regulation
covers sludge monofills only, the following sections relate primarily to
monofilling technology and processes.
1-1
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1.1 MONOFILLS
Most sludge-only landfills consist of a series of trenches dug into the
ground into which dewatered sludge is deposited and then covered with soil.
Other sludge-only landfill designs exist (area-fill mounds, area-fill layers,
and diked containment) in which the sludge is deposited on the ground surface,
but these designs are not commonly used. Sludge landfill trenches range from
1-15 meters (m) [3-50 feet (ft)] in width. When narrow trenches are used
[1-3 m (3-10 ft) wide], dewatered sludge is usually deposited in the trench
from a haul vehicle alongside the ditch. The sludge must be less than 30%
solids and the trench floor must be nearly level to ensure that the sludge
will spread evenly throughout the narrow trench. A wide trench [3-15 m (10-
50 ft) wide] allows the haul vehicle to work within the trench itself. In
this case, the sludge should be at least 30% solids (which may include bulking
material, such as fine sand) to ensure that it will stay in piles and not
slump. The addition of a bulking agent is generally not cost-effective if the
sludge solids content is less than about 20%. If the sludge solids content is
too low, the sludge should be further dewatered at the treatment plant.
The sludge is usually covered with soil the same day it is deposited to
minimize odors and to prevent insects, birds, and other vectors from
contacting the sludge and spreading contaminants. As each new trench is dug,
the excavated soil is used to cover the sludge in a nearby trench. If the
sludge is- solid enough to support a vehicle (greater than about 30% solids),
soil cover can be applied by a track dozer within the trench. For sludges
less than 30% solids, cover must be applied by a front-end loader or dragline
next to the ditch.
Generally, sludges must contain at least 20% solids in order to support
cover material. Narrow trenches can handle sludges as low as 15% solids
because the ground on either side helps support the cover, but narrow trenches
are relatively land intensive. Sludge applications range from about
460-2,120 dry metric tons per hectare (dry mt/ha) [200-940 tons per
acre (tons/ac)], including areas between trenches. Wide trench operations are
1-2
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less land-intensive than those using narrow trenches, with sludge applications
ranging from about 1,200 to 5,430 dry mt/ha (530-2,440 tons/ac).
At area fills, sludge is placed on the original ground surface.
Excavation is not required because sludge is not placed below the surface,
thus area-fill application is often used in areas with shallow bedrock or
ground water. There are three methods of area-fill application: area-fill
mounds, area-fill layers, and diked containment.
In area-fill mound applications, the sludge solids content should be no
more than 20%. Sludge is mixed with a soil-bulking agent to produce a mixture
that is physically more stable and has greater bearing capacity The sludge
is usually mixed at one location and then hauled to the filling area. At the
filling area, the mixture is stacked into mounds approximately 6 ft high, and
3 ft of cover material is applied.
In area-fill layer applications, sludge is received at the site and mixed
with a soil-bulking agent. The mixture is spread evenly in layers from 0.5-
3 ft thick in a number of applications. Interim soil cover is applied between
consecutive layers in 0.5-1-ft thick applications. Final soil cover is from
2-4 ft thick.
In diked containment applications, sludge is placed entirely above the
original ground surface. Dikes are constructed on level ground around all
four sides of a containment area. Access is provided to the top of the dikes
so that haul vehicles can dump sludge directly into the containment. Usually,
diked containment operations are conducted without adding soil bulking agents.
Diked containments are relatively large, with typical dimensions of 10-500 ft
wide, 100-200 ft long, and 1-30 ft deep.
1-3
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1.2 LEACHATE
Leachate is generated from the excess moisture in the sludge, usually with
some contribution from rainfall. The type and amount of constituents in
leachate from a sludge monofill depend on the nature of the sludge. Table 1 1
gives the range of constituent concentrations in leachate from several study
sites.
If monofill leachate reaches an aquifer, heavy metals and toxic organic
chemicals are of particular concern because of their possible adverse health
effects. If leachate enters surface waters, the resulting elevated nutrient
levels can cause eutrophication and concomitant undesirable algal blooms and
fish kills. Pathogen contamination of drinking water supplies also could have
adverse health effects.
The potential for groundwater contamination can be reduced by properly
covering monofills and by installing liners to contain any leachate within the
fill area. Leachate is then treated to attenuate harmful contamination. Most
States (72%) require or can require that soil-based liners, synthetic liners,
or both be installed in a sludge monofill.
A leachate collection system should be installed in any monofill where
leachate is being contained and where water tends to pond in the fill area.
The two types of collection systems are: (1) A sump into which leachate
collects and is subsequently pumped to a holding tank or pond, and (2) a
series of drain pipes or tiles that intercept and channel the leachate to the
surface or to a sump.
1.3 SURFACE WATER CONTAINMENT
Based on good management practices, all upland drainage should be directed
away from the monofill. Working areas of the monofill should have a grade
greater than 2% to promote runoff and prevent ponding, but less than 5% to
1-4
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TABLE 1-1. Range of Constituent Concentrations in Leachate from
Sludge Monofills
Constituent Concentration3
Chloride 20-600
S04 1-430
Total organic carbon 100-15,000
Chemical oxygen demand 100-24,000
Calcium 10-2,100
Cadmium 0.001-0.2
Chromium 0.01-50b
Zinc 0.01 36
Mercury 0.0002-0.0011
Copper 0.02-37
Iron 10-350
Lead 0.1 10b
TKNC 100-3,600
Fecal coliform 2,400-24,000
MPN/100 mLd
Fecal streptococcus 2,100-240,000
MPN/100 mLd
aConcentration is in milligrams per liter unless otherwise noted.
bThe maximum concentrations shown exceed the limits specified in
40 CFR 261.24 Table I. These limits define hazardous wastes under
RCRA.
cTotal Kjeldahl nitrogen.
dMPN/100 mL = most probable number/100 milliliters (mL).
Source: EPA, 1984.
1-5
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reduce flow velocities and minimize erosion. Straw bales, berms, or
vegetation can be used to reduce flow velocities. Siltation ponds will
probably be necessary to settle the solids contained in the site runoff.
1.4 GAS CONTROL
The decomposition of organic matter in sludge and solid waste produces
methane and other gases, including trace amounts of hydrogen sulfide. Methane
is the gas of primary concern. It can seep by diffusion through sludge and
other materials into nearby buildings or underground structures, such as
utility tunnels, where it may accumulate to explosive concentrations (5-15%)
To prevent this hazard, systems to collect gases usually are installed in
monofills located near buildings or underground structures. Collected gas can
be vented to the atmosphere or incinerated. Recovering the methane as an
energy source is usually not economical at monofills.
1.5 LAND REQUIREMENTS
Monofilling can require substantial amounts of land. For example, a
municipality generating 25 dry mt (28 dry tons) of sludge per day (i.e.,
population of about 230,000) will require approximately 2-20 ha (4-50 ac) of
land per year for monofilling, depending on trench width, fill-area depth, and
sludge solids content. This range is important because the areas suitable for
landfilling are limited by land-use concerns in the community. Finding and
gaining access to an adequate landfill site is often the most significant
problem in implementing a sludge landfill operation.
1-6
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A landfill has a finite size and, therefore, a finite operating life.
This operating life must be long enough to justify purchase, site preparation,
and other capital costs, which become less significant when amortized over
time.
A landfill's lifespan can be estimated by dividing the volume of sludge it
can hold by the volume of sludge landfilled each year. Landfill capacity is
the product of the usable fill area (generally 50-70% of the total site
surface area) times the depth of the landfill. The remaining 30-50% of the
site is used for buffer zones, access roads, and soil stockpiles. In
calculating landfill size requirements, the projected increase in sludge
volume during the lifetime of the site must be considered. This volume will
be a function of community growth and the construction of additional
wastewater treatment capacity. Soil is often used to increase the solids
content of a sludge and to provide interim and final cover. Bulking and cover
soil may be present on site and readily available from trench excavation. If
sufficient soil is not available on site, or if its physical and chemical
properties are not suitable, soil may have to be hauled to the landfill, a
costly procedure.
Pollution of ground and surface waters are the major environmental
concerns associated with monofilling. The depth to ground water, the type of
bedrock, and the soil environment affect the potential for groundwater
contamination. Any currently used or potentially potable ground water should
be protected from landfill leachate.
1.6 STORAGE
Storage space to accomodate at least several days' production of sludge
should be provided at the treatment plant in case transportation or labor
problems prevent hauling sludge to the landfill site. Onsite storage also is
desirable in case inclement weather or other problems disrupt site operations
1-7
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These disruptions can be minimized if special fill areas close to the landfill
entrance are designated for use only during inclement weather.
1.7 GOOD PRACTICES
Proper sanitary landfill site planning and management procedures will
minimize the potential for leachate formation and migration; methane
generation; and surface runoff, erosion, and siltation.
1.8 SLUDGE QUALITY
The physical characteristics of sludge are important for monofilling.
Sludges should be stabilized, dewatered, and mixed with bulking agents to
facilitate handling. The chemical characteristics of sludge, however, have
rarely been of concern. Chemical composition has been important only if a
sludge is classified as hazardous under the Resource Recovery Conservation Act
(RCRA). For this reason, prior to the proposed sewage sludge regulations,
sludges that were too highly contaminated for other use/disposal options, but
not contaminated enough to be classified as hazardous, were monofilled.
1-8
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SECTION TWO
RISK ASSESSMENT METHODOLOGY
2.1 INTRODUCTION
The Environmental Criteria and Assessment Office in the Agency's Office of
Research and Development (ORD) has developed detailed risk assessment
methodologies for four sludge disposal options: land application/distribution
and marketing, landfilling, incineration, and surface disposal. This section
discusses the methodology used to model risks associated with sludge-only
landfills or monofills and to develop risk-based maximum allowable
concentrations for contaminants in sewage sludge disposed in monofills.
The first step in developing the risk assessment methodology for sludge
monofills was to identify the major pathways of exposure through which each
sludge contaminant could reach and detrimentally affect humans, plants, or
animals. Mathematical expressions (algorithms) were then developed to
describe the transport, fate, and effects of the pollutants in each medium
(air, water, soil) Site-specific factors that influence exposure and
toxicity, such as soil or climatic variability and management practices, were
also incorporated in the algorithms. The risk assessment methodology was
peer-reviewed internally by the ORD and externally by the Agency's Science
Advisory Board (SAB) and then translated into computerized mathematical models
by the Office of Water Regulations and Standards (OWRS)
The set of computer models that incorporates this methodology,
collectively known as SLUDGEMAN, can estimate the risk associated with sludge
disposal in a given landfill. SLUDGEMAN is designed to calculate a reasonable
worst-case level of exposure to chemicals leaching from a landfill and emitted
to the atmosphere.
2-1
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2.2 IDENTIFICATION OF PATHWAYS OF EXPOSURE AND HEALTH AND
ENVIRONMENTAL CRITERIA
SLUDGEMAN predicts the movement of pollutants from a source landfill
through several environmental pathways to reach a nonhuman target organism or
a most-exposed individual (MEI) defined as an adult with a 70-year (yr)
exposure to long-term average contaminant levels released from a landfill near
his or her residence, at a calculated concentration. This calculated
pollutant concentration is compared to either an environmental impact
criterion or a human health criterion to determine the risk of disease to the
MEI. The following sections describe the health environmental criteria,
identified before the risk-assessment methodology was developed, and the key
pathways of exposure, identified during that development process.
2.2.1 Pathways of Exposure
Four environmental pathways were identified as critical to the analysis of
sludge monofills:
Contaminant infiltration to ground water
Vapor loss from fill material
Surface runoff
Suspension of contaminated particles from the working face
Figures 2-1 to 2-3 show routes of human exposure from landfilled sludge and
contaminant migration pathways for narrow- and wide-trench landfills. The
first two pathways were identified as the key pathways of contamination and
were modeled in EPA's SLUDGEMAN model.
Infiltration of sludge contaminants to ground water and subsequent
ingestion of this water by humans was considered the most significant of the
potential pathways, based on the likelihood of occurrence. The MEI for this
groundwater pathway was defined as an adult residing at the property boundary
2-2
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Alrborn*
Pollution
Vapor
Landflllad
Sludg*
Olssolvcd In
Laaenat*
Unsaturatad
Soil
Olssolvad
Pvtlcuiatasr
Runoff
Dlsxolvad and
Attacncd to
Susp«na»d Matter
Human
S*<"»u"
Crop/Uv«stoek
Consumption
Saturatad
around watar
Drinking
Watar
Irrigation/
UvastocK
Watar
Racharg*
Body
Withdrawal
for Us*
FIGURE 2-1. Routes to Human Exposure from Landfilling Sludge
2-3
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ho
I
.(S
W»Ur TabU
FIGURE 2-2. Contaminant Migration Pathways for Narrow Trench Landfills
-------
(T) Va|»oi
~ V\r V
IK.UUI, 2-.^. Oiiilamiiianl Migration I'atliways lor I'it or Wide Trench l^ndfillls
-------
of the landfill who drinks 2 liters (L) of the ground water every day for his
or her entire 70-yr lifespan.
Vapor loss of volatile compounds is also a very likely source of
contamination. Vapor loss may be caused by volatilization from the uncovered
working face of the landfill or contaminant releases from within the fill and
subsequent migration of these contaminants through the soil cover. Vapor loss
from sewage sludge landfills was identified as a possible source of
contamination from benzene, cyanide, dimethylnitrosamine, and
trichloroethylene. The ME I for the vapor pathway was defined as an adult
residing at the property boundary of the landfill who inhales vapors from the
site 24 hours (hr) a day for his or her entire 70-yr lifespan.
The third pathway, surface runoff, is one of the least likely routes of
exposure because:
Soils are used for cover, making the working face the only significant
source area for contaminated runoff.
At landfills where the working face is below the grade of the
surrounding areas, runoff will be contained by the facility design.
Where the working face is not below grade, the regulation requires
that drainage be contained in the downflow direction (runon controls)
The fourth pathway, suspension of contaminated particles from the working
face, is also an unlikely route of exposure because the face of the fill will
not be exposed for more than 8-12 hr/day and because threshold wind speeds
necessary for suspension rarely would be exceeded for any length of time.
This pathway, as well as the surface runoff pathway, is not modeled by
SLUDGEMAN.
2.2.2 Human Health and Environmental Impact Criteria
The criteria used in the risk assessment methodology were derived from
different sources, depending on the type of pollutant:
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For noncarcinogens, the human health criterion is the daily intake of a
pollutant that will cause no adverse effect; it is considered a
threshold value for that contaminant. The model uses the Agency's
established Risk Reference Doses (RfDs) for humans as the threshold
values for chronic toxicity.
For plants and animals, the model uses chronic toxicity threshold
values reported in the scientific literature.
For carcinogens, no dose is considered "safe"; only a zero dose is
associated with zero risk. The Agency's Carcinogen Assessment Group
has estimated the carcinogenic potency (i.e., the slope of the curve
plotting risk versus exposure) for humans exposed to low-dose levels
of carcinogens (EPA, 1987a). These potency values are used in the
model to derive the exposure level expected to correspond to a given
level of excess risk. Incremental risk levels of 10"* (one additional
cancer case in one million people) to 10"4 (one additional cancer case
in ten thousand people) were evaluated for the proposed sewage sludge
regulation.
Maximum Contaminant Levels (MCLs) established by EPA's Office of
Drinking Water are used as the drinking water criteria for the
groundwater contamination pathway
For the seven groundwater pollutants that have no proposed MCLs, the
target concentrations were either the carcinogenic potency (qj*) values
associated with specific risk levels for the MEI, or the RfD.
SLUDGEMAN back-calculates the maximum allowable pollutant concentrations that
would yield the RfD, MCL, or appropriate carcinogenic dose at the exposure
point for the MEI or target organism.
2.3 OVERVIEW OF SLUDGEMAN
SLUDGEMAN incorporates a number of computer models and submodels that are
designed to represent the leaching of contaminants from a source and the fate
and transport of the leached material through a zone of unsaturated soil
(where the spaces between soil particles are filled with both air and water)
and into and through a saturated zone, typically considered an aquifer. The
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model also predicts the release of volatile contaminants into the atmosphere.
SLUDGEMAN's major components are:
. Two models that determine the rate at which each contaminant of concern
leaches from the monofill (SATM1 and SLUGMAIN)
A model that determines the rate of contaminant transport through the
unsaturated zone and the processes that occur in this zone to degrade
contaminants or retard transport (CHAIN)
A model that predicts the transport and fate of contaminants in the
saturated zone (AT123D)
. A model that integrates CHAIN and AT123D (AT123DIN)
Two models (SATIT and ALLCON) that (1) calculate the rate of release to
and the concentrations of volatile contaminants in the atmosphere and
(2) determine the allowable concentration of contaminants in sludge
using the results of both the groundwater and vapor pathway modeling
Section 2.4 discusses the methodologies incorporated in the five major
groundwater models (SATM1, SLUGMAIN, CHAIN, AT123DIN, and AT123D), Section 2.5
discusses the two vapor release models, and Section 2.6 presents the
methodology used to back-calculate maximum concentrations of contaminants in
sludge based on the criteria and the predictions of the SLUDGEMAN models
Finally, Section 2.7 presents a summary of the comments generated by SAB's
review of SLUDGEMAN and EPA's responses to those comments.
SLUDGEMAN performs two types of analyses using the component models listed
above. For monofills located over Class I aquifers, SLUDGEMAN uses SATM1,
CHAIN, and SATIT to predict groundwater concentrations and vapor loss and to
back-calculate allowable concentrations of contaminants in sludge. The Class
I aquifer analysis assumes the leachate is not transported in the aquifer, but
is ingested by the MEI in the same concentration at which it enters the
aquifer. Thus AT123D, which models transport through the saturated zone, is
not used. Class I aquifers are treated very conservatively because they are
highly vulnerable to contamination, being either irreplaceable as sources of
drinking water to substantial populations or ecologically vital.
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For monofills located over Class II aquifers (ground water that is not
classified as Class I, and that either is used currently or is available as a
potential source of ground water), the model uses SLUGMAIN instead of SATM1 to
calculate leach times. The model for monofills over Class II aquifers also
uses the saturated zone transport model AT123D and the unsaturated transport
model CHAIN. Additionally, the ALLCON model, rather than SATIT, is used to
predict volatile contaminant concentrations in the atmosphere and to calculate
allowable sludge concentrations. During transport in the saturated zone
(aquifer), contaminants can be diluted or degraded; thus the criteria
generated are less stringent than those generated using the Class I analysis.
A few additional analytical distinctions are made in modeling the two
types of monofills. For monofills located over Class II aquifers, SLUDGEMAN
calculates downgradient pollutant concentrations on the centerline of the
monofill rather than on the edge of the monofill, because the highest
pollutant concentrations are expected along the centerline. The model also
assumes the monofill is contiguous to one edge of the aquifer, so that
pollutants are modeled to disperse laterally into the center of the aquifer
from the edge. This approach yields higher downgradient concentrations than
those calculated assuming the monofill were centered in the aquifer with
lateral dispersion occurring in both directions toward the sides The
assumption that the monofill is located contiguously to one edge of the
aquifer is realistic because monofills can be placed in any location relative
to an aquifer, including near one edge.
Monofills can be located over other types of aquifers, including Class
IIIA and IIIB aquifers and their subclassifications. SLUDGEMAN does not
distinguish monofills located over Class IIIA and IIIB aquifers from those
over Class II aquifers because Class III aquifers also are not used as sources
of drinking water. Class IIIA aquifers yield insufficient water or have
solids content greater than 10,000 milligrams (mg/L). Class IIIB aquifers are
contaminated naturally or by human activity and cannot be cleaned up using
reasonable water treatment methods.
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2.4 DESCRIPTION OF THE GROUNDWATER COMPONENTS OF THE
SLUDGEMAN MODEL
SLUDGEMAN's groundwater components consist of a number of sequential
models that vary depending on the type of aquifer to be modeled. These models
include leachate pulse-time calculations (SATMl and SLUGMAIN), an unsaturated
zone fate and transport model (CHAIN) , a saturated zone fate and transport
model (AT123D), and a model that integrates CHAIN and AT123D (AT123DIN). A
discussion of each of these models follows.
2.4.1 Pulse-time Calculation (SATMl and SLUGMAIN)
Leaching of contaminants out of a monofill does not happen instantly The
leachate pulse time is the length of time from the beginning to the end of
leaching, i.e., when all leachable materials have migrated from the monofill.
The SATMl model is used to calculate the pulse time in Class I aquifer
simulations; SLUGMAIN is used to calculate pulse time in Class II aquifer
simulations. The input data required for these calculations include:
concentrations of pollutants in the leachate, concentrations of pollutants in
the sludge (dry weight), sludge moisture content, sludge storage capacity,
sludge density, net recharge rate, width and length of the landfill, and
height of the fill material. These parameters and assigned values are
discussed in detail in Section 3.
Several assumptions are made in calculating pulse time: (1) the estimated
leachate concentrations are an approximation of leachate strength, (2) all the
contaminants ultimately solubilize, and (3) the leachate pattern is a pulse of
equal height throughout its duration (i.e., a square wave, rather than a curve
representing a gradual increase followed by a gradual decline in the amount of
contaminants leaching from the monofill). The results of the pulse-time
calculation are used as an input to CHAIN, which calculates contaminant
concentrations in the unsaturated zone. The parameters total contaminant
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levels in the sludge, contaminant concentrations in the leachate, sludge
moisture content, and recharge rate are used to calculate pulse time. These
factors are relevant to pulse time according to:
Q = M/X (1)
and
Q = RT + (L - S) (2)
where Q = volumetric water flow of leachate per square meter (m2) required
for the contaminant to be completely leached; the units for Q are
in m3
R = recharge of infiltrate volume entering the landfill, in m2/yr.
This can be calculated as: R = P ET RO, where P is
precipitation, ET is evapotranspiration loss, and RO is runoff
S = storage capacity for water in sludge, defined as the "dry" water
content per m2 for the sludge under normal atmospheric conditions,
i.e., the product of fill height after drainage, sludge density,
and moisture content divided by 1,000 kilograms (kg)/m3
L = water content of sludge per m2 at time of disposal, i.e. , the
product of fill height, sludge density, and moisture content
divided by 1,000 kg/m3; the units for L are in m3
T = the pulse time over which all contaminant will be released from
the sludge, in yr
M = mass of contaminant contained in a volume of sludge
represented by the height of the sludge in the -fill and a m1 cross
section, i.e., M = (height of fill x 1.0 m3) x (density of sludge,
kg/m3) x (concentration of contaminant in sludge, kg/kg) x (1
moisture content); the units for M are in kg
X = concentration of leachate contaminant in kg/m3
All of these parameters are discussed more fully in Section 3.
When equations 1 and 2 are combined, the pulse time T can be calculated:
T - M - X(l - S) (3)
XR
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For degradable contaminants, the initial mass of contaminant, M, changes
with time. If a first-order decay mechanism is assumed at a degradation rate
d, the equation becomes:
= -1 [In XR 1 (4)
d XR - dM
where T = pulse time, yr
d = degradation rate constant, yr"1
X = leachate concentration, kg/m
R = recharge rate, m3/yr
M = mass of contaminant in sludge, kg
2.4.2 Unsaturated Zone Model (CHAIN)
CHAIN is the analytical model used to solve the one-dimensional
convective-dispersive transport equation for the unsaturated zone (Van
Genutchen, 1985). This model predicts the way dispersion elongates the
leachate pulse as it moves through the unsaturated zone, resulting in
decreasing contaminant concentrations. The CHAIN model itself is composed of
several submodels. These submodels calculate the length of time it takes the
leachate to travel through the unsaturated zone to the saturated zone below,
and the rates of retardation and degradation of contaminants in the
unsaturated zone. Length of travel time, retardation, and degradation
calculations used in the CHAIN model are discussed below.
The MINTEQ model, which predicts the fate of dissolved metals, is also
discussed in this section. MINTEQ, which is not part of CHAIN, was run
separately, and the results were used to adjust the metals concentrations
predicted by CHAIN to account for precipitation of metals from the leachate.
These adjustments are "hard-wired" into the CHAIN model and do not need to be
input.
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2.4.2.1 Travel-time Calculation
The unsaturated zone consists of the layers of soil between the landfill
and the uppermost aquifer. To determine the concentration of a contaminant at
the base of the unsaturated zone, the travel time must be calculated. The
travel time is the length of time it takes the leachate to travel through the
unsaturated zone; it is determined using the depth to ground water and the net
recharge rate.
Two basic approaches can be used to determine travel time in the
unsaturated zone: (1) analytical models and (2) unsaturated flow models.
Both approaches are based on the same fundamental equations but differ in the
simplifying assumptions made to solve the equations. Analytical models
require fewer data, are computationally easier to use, and generate solutions
much more rapidly than unsaturated flow models. Consequently, the Agency
selected an analytical model to predict unsaturated zone concentrations of
contaminants. Analytical models, however, require the assumption of steady-
state conditions. As a result, they predict a constant contribution of
leachate over time rather than the periodic storm event contributions that
actually occur. This simplifying assumption generally leads to results that
overpredict velocity, underpredict travel time and degradation, and
overpredict concentrations in the unsaturated zone.
Analytical solutions of travel time through the unsaturated zone are based
on Darcy's law for one-dimensional flow. Darcy's law is a mathematical
description of water flow through a porous medium, and is given in terms of
the following equation:
V, = K ty/J 5fe> (5)
<5z
where Vz = seepage velocity in the vertical direction
lJm = matric potential (suction head or negative pressure head)
= hydraulic conductivity as a function of matric potential
= hydraulic gradient in the vertical direction
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In unsaturated flow, both hydraulic conductivity and moisture content are
nonlinear functions of pressure head. Hydraulic conductivity, moisture
content, and pressure head need not be constant throughout a soil column;
however, if they are not, a direct analytical solution of Darcy's equation is
not possible for unsaturated flow. To solve Darcy's equation for travel time
in the unsaturated zone, the following assumptions must be made:
There is one-dimensional flow in the vertical direction.
Water flow is steady state.
Water table conditions exist at the lower boundary.
The upper boundary has a constant flux.
Soil characteristics (moisture content versus matric potential and
hydraulic conductivity versus matric potential) are constant with
depth.
The hydraulic gradient is sloped vertically downward and equals unity
(drainage is caused strictly by gravity, or 6p>/6z = 0)
For nonhomogeneous soils, the constant property assumption can be approximated
by dividing the soil profile into a series of layers, then calculating travel
time for each layer individually.
The unit gradient assumption greatly simplifies the analysis. Under this
assumption matric potential and, therefore, moisture content and hydraulic
conductivity, remain constant with depth. When this assumption is made,
moisture content can be solved directly in terms of flux through the system
and saturated soil properties. When the moisture content and flux are known,
the pore water velocity and the travel time through the unsaturated zone can
be calculated. The unit gradient assumption generally is valid if
gravitational forces dominate other forces (e.g., capillary forces).
If the unit assumption is not made, the analytical solution to
unsaturated flow becomes more complex. In this case, calculations for
pressure head and moisture content must be solved iteratively. Deriving
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iterative solutions is a time-consuming task, but can be simplified by using a
computer.
All analytical solutions for travel time through the unsaturated zone are
one-dimensional. When applying these solutions to specific sites, the
horizontal variability of soil characteristics must be considered. If soil
characteristics vary spatially, the solution should be applied to the soil
profile having the highest hydraulic conductivity. The solution will then
yield the highest velocity and shortest travel time (i.e., worst case) for the
unsaturated flow system. The solution, which is the water travel time (TW),
must then be modified by a retardation factor. A more detailed treatment of
the theory and equations used in travel time calculations may be found in the
Technical Guidance Manual for Calculating Time of Travel (TOT) in the
Unsaturated Zone (EPA, 1985c).
2.4.2.2 Retardation Factor
Contaminants will travel either with the leachate or at a slower velocity
depending on the degree to which they are adsorbed onto soil particles.
Retardation is a measure of how slowly a contaminant moves through the
unsaturated zone with respect to the bulk of the leachate. The retardation
factor is calculated from model input data on the bulk density of the
unsaturated zone material, the partition coefficient of the contaminant,
hydraulic conductivity, effective porosity, effective bulk density, slope of
the curve plotting matric potential versus moisture content, and the saturated
moisture content of the unsaturated zone material. These input parameters and
their assigned values are discussed in Section 3.
The retardation factor (R) for a particular contaminant can be calculated
by the equation:
R = 1 + (B/9XK,) (6)
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where B/9 = soil-to-solution ratio (bulk density of the soil divided by
its effective porosity)
Kd = distribution coefficient
Kj can be measured in the laboratory or obtained from the literature for a
wide range of soil types and contaminants. Values for K<, are discussed in
Section 3.
2.4.23 Degradation
The travel time for a contaminant through the unsaturated zone (TC) can be
estimated as the water travel time (TO) , derived in the travel time
calculation, times the retardation factor for that particular contaminant, as
represented by:
TC = TW x R (7)
Reductions in pollutant concentration due to degradation processes, such
as hydrolysis and biochemical oxidation are characterized by a degradation
constant, d. This constant can be related to the environmental half-life of a
pollutant, represented by tV2, the time required for the contaminant
concentration to be reduced to one-half its initial value. If a first-order
decay mechanism is assumed, the concentration X at any time can be defined as:
X = X,, e-* (8)
where X,, = the initial concentration of X
t = time
Therefore, the half-life, tm, can be derived as:
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in 2L
A.
or
= In2 (10)
d
Equation 8 can be used to determine the degree of degradation that will
occur as the leachate moves through the unsaturated zone. In this way, the
leachate concentration from the source, X, can be converted to the value
predicted at the point where the leachate enters the aquifer. This conversion
is accomplished by inserting the contaminant travel time in the unsaturated
zone, TC , into Equations 7 and 8:
X = Xe^0 (11)
or
(-InZTC)
X = Xe"1^
The resulting value for X is the contaminant concentration that should be
applied to all subsequent saturated zone transport calculations . The above
equation gives the pollutant concentration reduction in the unsaturated zone
caused by degradation. That is, the calculation conservatively assumes that
the contaminant plume moves as a pulse through the unsaturated zone, with no
dispersion. In actuality, dispersion elongates the contaminant pulse as it
moves through the unsaturated zone, with a resulting decrease in
concentration .
2.4.2.4 Metals Modeling (MINTEQ)
After CHAIN is used to determine contaminant concentrations at a depth
equal to the depth to ground water for a period of several contaminant travel
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times, the concentrations of metals must be adjusted to account for any
precipitation of metal compounds that exceed solubility limits. The MINTEQ
model is used to calculate -the mass distribution of a dissolved metal between
various uncomplexed and complexed aqueous species and to predict the
precipitation and dissolution of these species (Felmy et al., 1984). MINTEQ
was run for a wide range of conditions, and the results were programmed into
the Agency's landfill model.
When the pH and Eh (oxidation-reduction potential) of the ground water are
known, CHAIN can automatically adjust metal concentrations at the base of the
unsaturated zone using the MINTEQ calculations for those conditions. After
these adjustments are made, CHAIN compares the maximum concentrations of
metals and organic contaminants to the drinking water criteria. For Class II
groundwater analyses, if the maximum concentrations are below the criteria,
the modeling analysis can be concluded without analyzing saturated zone
transport. If the predicted concentrations exceed the criteria, then
contaminant transport in the ground water must be simulated.
2.4.3 Saturated Zone Model (AT123D)
Analytical solutions and numerical modeling are the two basic approaches
for estimating contaminant travel time and concentrations in saturated
groundwater flow systems. The Agency selected an analytical groundwater
model, AT123D, because this approach requires fewer data, is less time
consuming to establish and run, and requires no expensive equipment or
specialized expertise.
AT123D is the analytical model used to solve the advective-dispersive
transport equation for the saturated zone (Yeh, 1981) Advection accounts for
the movement of solutes with the mean velocity of the water Dispersion of
the leachate plume occurs because solutes travel more slowly near the walls of
the soil pores than in their centers and faster in larger pores. Molecular
diffusion also is included in AT123D to account for spreading of the leachate
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plume due to random molecular motion. Additionally, AT123D calculates the
sorption and decay of contaminants. Input data required for the model include
the type of material in the saturated zone, mixing thickness of the aquifer,
hydraulic conductivity, effective porosity, hydraulic gradient, effective bulk
density, width of the saturated zone, partition coefficients, decay rates,
background groundwater concentrations for each contaminant, and the distance
to the compliance point. The algorithms incorporated in this model are not
presented here. The interested reader can find a discussion of the highly
complex mathematical expressions used to model saturated transport modeling in
Yeh (1981). The parameters used as input to the model and their assigned
values are discussed in Section 3.
The Agency's goal is to field-validate all the risk-based models used to
support the proposed rule. AT123D has not yet been field-validated, but the
theory behind the model is well known and accepted by groundwater experts, and
it is widely used by the Agency to support regulations and investigations by
EPA's Office of Toxic Substances and Office of Solid Waste.
2.4.4 Integrating the Unsaturated and Saturated Zone Models (AT123DIN)
To integrate between the CHAIN unsaturated zone model and the AT123D
saturated zone model, the contaminant concentrations output from CHAIN must be
converted to mass flux rates from an appropriate repository. The repository
is defined as the area below the landfill to a depth in the aquifer equal to
the mixing depth of the leachate from the landfill. The amount of contaminant
mass leaching into the aquifer annually is the concentration of each
contaminant times the recharge rate times the area of the landfill. The
annual mass flux exiting the area below the landfill is either the total
annual mass flux, if the groundwater flow rate is sufficient to carry the
total mass of leachate away each year, or a fraction of this amount equal to
the fraction of the landfill length that the ground water travels in a year.
The mass flux from the area below the landfill is therefore equal to the
contaminant concentration times the recharge rate times the landfill width
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times the minimum of the landfill length and the groundwater velocity. The
result of this calculation is the mass flux value needed as input to AT123D.
If the groundwater flow is insufficient to carry away all the contaminant
leachate that enters the aquifer each year, then the release time for
contaminants into the aquifer is increased by the ratio of the length of the
landfill to the annual groundwater travel distance. This adjustment accounts
for the increased length of time required to wash away all contaminants from
beneath the landfill.
2.5 DESCRIPTION OF THE VAPOR PATHWAY COMPONENTS OF THE
SLUDGEMAN MODEL
Vapor loss from landfills has been identified as a potential problem for
certain volatile toxic chemicals such as benzene, cyanide,
dimethylnitrosamine, and trichloroethylene. To estimate landfill vapor loss,
the Agency is using (in SATIT and ALLCON) the same analytical model that was
developed to evaluate vapor loss and dispersion of contaminants from hazardous
waste sites in the landfill ban analysis (Environmental Science and
Engineering, 1985). The vapor loss models consider three periods: (1) the
operating period with uncovered wastes, (2) the period of shallow temporary
cover, and (3) the post-closure period with permanent cover. The models
assume that pollutants will evaporate from the monofill for a total of 70 yr.
The monofill is assumed to be active for 20 of those 70 yr, during which the
sludge deposited each day is assumed to remain open to the air for an average
of 4 hr. The sludge is therefore assumed to be open to the air 1/6th of the
time for the first 20 years, covered with a temporary cover for 5/6ths of that
time, and covered with a final cover for 50 yr. Degradation and deposition
are not considered because travel times are relatively short and the Agency
wanted to be conservative in estimating potential vapor concentrations.
For the operating period, during which wastes remain uncovered, the model
assumes that volatilization depends directly on wind speed. The model
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predicts the maximum possible exposure to vapor concentrations because it
assumes that (1) wind speed and direction are constant, (2) stable atmospheric
conditions prevail, and (3) the receptor is located downwind and along the
centerline of the plume.
For the two periods when wastes are covered, the model assumes that the
loss rate of contaminants is independent of wind speed and is controlled by
diffusion of contaminants through the soil. The model assumes that the final
soil cover applied to a landfill cell has the same permeability as that of the
temporary soil cover. In practice, because the final soil cover is usually
less permeable, the model assumption leads to an overprediction of loss rates
The rate at which pollutants evaporate from a monofill is estimated using
Henry's law constants, a method that also leads to overprediction. Henry's
law states that the mass of any gas that dissolves in a given volume of liquid
at constant temperature is directly proportional to the pressure that the gas
exerts above the liquid. The use of Henry's law can be avoided if adequate
data specifying the vapor pressure of each contaminant are available. Because
vapor pressures are not measured routinely, the model uses Henry's law to
specify vapor concentration as a function of liquid concentration. Henry's
law is most appropriate for low concentrations of dissolved pollutants and low
solids content sludges. As pollutant concentrations and solids content
increase, Henry's law tends to overpredict vapor pressure as a result of
activity effects and partitioning between solid and liquid phases.
The models are written to calculate vapor concentrations for six of the
ten organics of concern: benzo(a)pyrene, bis(2-ethylhexyl)phthalate,
chlordane, DDT/DDD/DDE, dimethylnitrosamine, and polychlorinated biphenyls
(PCBs). Dimensionless Henry's law constants and molecular weights have been
incorporated into the model for these chemicals.
In addition to Henry's law constants and the molecular weight of
contaminants, other input data are required for the vapor loss models,
including average wind speed and air temperature, porosity of cover soil,
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times the minimum of the landfill length and the groundwater velocity. The
result of this calculation is the mass flux value needed as input to AT123D.
If the groundwater flow is insufficient to carry away all the contaminant
leachate that enters the aquifer each year, then the release time for
contaminants into the aquifer is increased by the ratio of the length of the
landfill to the annual groundwater travel distance. This adjustment accounts
for the increased length of time required to wash away all contaminants from
beneath the landfill.
2.5 DESCRIPTION OF THE VAPOR PATHWAY COMPONENTS OF THE
SLUDGEMAN MODEL
Vapor loss from landfills has been identified as a potential problem for
certain volatile toxic chemicals such as benzene, cyanide,
dimethylnitrosamine, and trichloroethylene. To estimate landfill vapor loss,
the Agency is using (in SATIT and ALLCON) the same analytical model that was
developed to evaluate vapor loss and dispersion of contaminants from hazardous
waste sites in the landfill ban analysis (Environmental Science and
Engineering, 1985). The vapor loss models consider three periods: (1) the
operating period with uncovered wastes, (2) the period of shallow temporary
cover, and (3) the post-closure period with permanent cover The models
assume that pollutants will evaporate from the monofill for a total of 70 yr.
The monofill is assumed to be active for 20 of those 70 yr, during which the
sludge deposited each day is assumed to remain open to the air for an average
of 4 hr. The sludge is therefore assumed to be open to the air l/6th of the
time for the first 20 years, covered with a temporary cover for 5/6ths of that
time, and covered with a final cover for 50 yr. Degradation and deposition
are not considered because travel times are relatively short and the Agency
wanted to be conservative in estimating potential vapor concentrations.
For the operating period, during which wastes remain uncovered, the model
assumes that volatilization depends directly on wind speed. The model
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Therefore, the limiting leachate concentration must be related back to a
limiting sludge concentration.
For organic contaminants, the relationship between their concentrations in
sludge and their concentrations in leachate is defined by the distribution
coefficient Kj. This coefficient defines a constant relationship between the
sludge concentration (Sc) and the leachate concentration (L,,) such that
Sc = L,. x Kj. The partition coefficient K^ and its derivation are discussed in
Section 3. With Kj and the limiting leachate concentration (L,.,) determined by
the model, the limiting sludge concentration (Sci) is calculated from Sd = Kd *
For metal constituents, the relationship between contaminant concentration
in sludge and that in leachate is more difficult to define. Metal
concentrations in leachate are often defined by solubility constraints rather
than by partitioning. In this case, leachate levels will stay at the
solubility threshold regardless of the sludge concentration. It is the
duration of the release of metals at the solubility limit that affects the
outflow concentration at a monitoring point. Given a constant recharge rate,
chemical release time is governed by sludge pollutant concentration. The
higher the sludge pollutant concentration, the longer the chemical is
released, and the more the outflow concentration approaches the leachate
concentration or solubility limit. The model conventionally assumes that the
highest reported effluent or leachate value for the metal constituent defines
the solubility limit. The sludge concentration can then be varied to
determine the inventory of contaminants producing maximum acceptable dose
levels at the point of exposure.
Different types of sludges will affect a metal's chemistry differently
and, therefore, its maximum solubility level in leachate. To accommodate this
sludge-specific factor, a leachate test can be conducted to determine
empirically the actual leachate concentration. Then the relationship derived
from the sludge's total contaminant level and the leachate concentration can
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be used to convert the limiting leachate concentrations to a sludge criteria
for that site.
For some metals, the back-calculation is not straightforward due to
complicated geochemistry. Also, the sorption characteristics in the aquifer
are not linear. The relationship between the dry-weight concentration of a
pollutant in the sludge and the final concentration at the point of compliance
is therefore nonlinear.
Because of this nonlinear relationship, an iterative approach is required
to solve for the allowable dry-weight concentrations in sludge. For the
iterative process, an initial set of typical dry-weight concentrations are
input into the model. Using these inputs, the model then calculates output
concentrations at the point of compliance, which are compared to the human
health criteria for each pollutant. The dry-weight concentrations for each
pollutant are then adjusted appropriately, and ALLCON writes the new dry-
weight concentrations to a new input file to be used in another model run.
The model is rerun, the new results are compared to the human health criteria,
the dry-weight concentrations are adjusted again, and a new input file is
written. After several such model runs, the output concentrations of
contaminants should approach the human health criteria and the dry-weight
concentrations of contaminants should approach the allowable sludge dry-weight
concentrations.
If no upper limit to the dry-weight concentration for a given pollutant
appears to be generated, the model limits the dry-weight concentration to
10,000 mg/kg (1% pollutant by weight, a reasonable upper limit). This step
prevents the model from spending needless time calculating unreasonable dry-
weight concentrations of contaminants in cases, for example, in which the
leachate concentration of a pollutant is less than its human health criterion.
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2.6.2 Vapor Pathway Calculation
Because total pollutant concentrations at the point of compliance are
required, the calculated vapor concentration must be added to the calculated
leachate and background concentrations of the groundwater pathway for each
pollutant. The model calculates vapor concentrations in mg/m3, whereas liquid
concentrations are calculated in mg/L. Therefore, the vapor concentrations
must be converted to equivalent liquid concentrations before they can be
summed to produce a total concentration for comparison with the human health
criterion.
The model assumes that a 70-kg person breathes about 20 m3 of air per day
and drinks about 2 L of water per day. Thus, if the air contains 1 micrograms
(Mg)/mJ of a pollutant, the person is breathing 20 Mg of the pollutant per
day. Because the person is assumed to drink 2 L of water per day, inhaling 20
Mg of a contaminant daily is equivalent to drinking water containing 10 Mg/L
of that contaminant. Ten Mg/L is equivalent to 0.01 mg/L. Thus, 1 MS/3
vapor concentration is equivalent to 0.01 mg/L liquid concentration. Under
these assumptions, the model multiplies the vapor concentration in p>g/m3 by
0.01 to covert to equivalent liquid concentrations in mg/L. The pollutant
concentrations then can be summed for comparison with the human health
criterion.
2.7 SCIENCE ADVISORY BOARD REVIEW
The SAB reviewed the groundwater and vapor modeling used in SLUDGEMAN.
The SAB had four major recommendations regarding the groundwater modeling:
The unsaturated zone should be modeled with PRZM (another unsaturated
zone model) instead of CHAIN.
The unsaturated zone should be modeled assuming anaerobic conditions.
The model should be modified to simulate the effect of liners. »k
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The model should be expanded to include the groundwater-to-surface
water pathway and implications for the wildlife food chain, crop
uptake, and bioaccumulation by edible aquatic organisms.
The CHAIN model predicts constant infiltration over time. This steady-
state approach tends to overpredict velocity, underpredict travel time and
degradation, and overpredict contaminant concentration. PRZM uses a curve-
number approach derived by the U.S. Department of Agriculture's Soil
Conservation Service to distribute daily rainfall into runoff and
infiltration. Infiltrating water cascades downward to successively deeper
layers as the soil water content of each layer exceeds field capacity. PRZM's
dynamic approach allows consideration of pulse loads and prediction of peak
events and estimates time-varying mass emission or concentration profiles.
The Agency's steady-state approach was designed to predict long-term
effects over the MEI's 70-yr lifespan. Short-term fluctuations in pollutant
concentrations predicted by PRZM average out in such an analysis. The steady-
state CHAIN model is adequate for the slowly degrading chemicals currently
being regulated for sludge disposal in landfills. In the future, if more
rapidly degrading chemicals are added to the regulation, the effects of short-
term fluctuations will be evaluated using a dynamic modeling approach such as
PRZM.
The Agency agreed with the SAB recommendation that anaerobic conditions
should be assumed for the unsaturated zone below a sewage sludge landfill.
The dissolved organics that leach out of these landfills are expected to
produce an anaerobic environment. The current version of the Agency's
landfill model includes anaerobic biodegradation rates and hydrolysis rates
for the regulated pollutants.
The SAB also suggested that the Agency's landfill model simulate the
effect of liners on leachate quality and quantity. The Agency decided against
this suggestion because liners are not being required in this regulation and
generally are not in use at sewage sludge monofills. The model is based on
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the conservative assumption that no liner is present, so that the calculations
will yield the most protective maximum allowable sludge concentrations.
The Agency decided to postpone action on the SAB recommendation that the
model be expanded to consider the groundwater-to-surface-water pathway The
Agency is convinced that the existing groundwater and vapor analysis accounts
for the most likely pathways of human contamination. The Agency is requesting
public comment on the need to consider the groundwater-to-surface-water link
and its effects on human and ecosystem health. Based on public comments, the
Agency will consider adding this surface-water pathway to the model.
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SECTION THREE
DATA BASE FOR THE RISK MODEL
As discussed in Section 2, the SLUDGEMAN model, along with its associated
submodels, is used to calculate the pollutant concentrations in sludge that
will allow a particular risk level (specified as a set of human health or
environmental impact criteria) to be met. Before the SLUDGEMAN model can be
run, however, a number of parameters must be specified. These parameters
define (1) a model sludge type; (2) groundwater conditions, saturated and
unsaturated zone conditions, and landfill surface dimensions for the
hypothetical site; and (3) chemical-specific factors, such as sludge
contaminant concentrations. This section presents the values assigned to each
parameter and discusses the basis for the choice of each value. Table 3-1
presents a summary of all the parameters to be defined with their assigned
values (except for the chemical-specific parameters, which are too numerous to
list here) Some of these values are input by the user; others are "hard-
wired" into the program.
3.1 MODEL SLUDGE PARAMETERS
The model requires that a specific sludge type be defined. Sludges are
defined primarily by their water or solids content, their storage capacity,
their density, and their specific gravity. The parameters that define the
model sludge follow.
3.1.1 Sludge Moisture Content
The value selected to represent the model sludge moisture content is 0.8
kilograms (kg)/kg, which indicates a sludge with a solids content of 20%.
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TABLE 3-1. Summary of Model Parameters and Assigned Values
Parameter
Value
Sludge Parameters
Sludge moisture content
Sludge storage capacity
Sludge density
Specific gravity (solids)
General Hvdrologic Parameters
Net recharge
Depth to ground water (Class I; other)
Aquifer thickness
Ground water pH
Ground water Eh
Saturated soil hydraulic conductivity
Unsaturated Zone Parameters
Unsaturated soil type
Bulk density in saturated zone
Effective porosity in saturated zone
Saturated zone hydraulic conductivity
Hydraulic gradient in saturated zone
Surface Parameters
Landfill site geometry
Distance to property boundary
Surface wind velocity
Air temperature
Air-filled porosity of cover soil
Total porosity of cover soil
Cover thickness (active and final)
Chemical-specific Parameters
Concentrations of sludge contaminants in sludge
Concentrations of contaminants in sludge leachate
Distribution coefficient
Saturated and Unsaturated zone decay rate
Background concentrations of contaminants
Health effects levels
Molecular weight
Henry's law constants
0.8 kg/kg
0.90 kg/kg
1,025 kg/m3
1.125
0.5 m/yr
Om; 1m
15 m
6 su
500 mv
10,000 mg/yr
Sand
2,380 kg/m3
0.1 m3/m3
2,000 m/yr
0.005 m/m
100 m x 100 m x
3.46 m
Cell length = 8 m
150 m
1 m/sec
15° C
0.1 m3/m3
0.4 m3/m3
0.3 m; 1 m
See
See
See
See
See
See
See
See
Sec.
Sec.
Sec.
Sec.
Sec .
Sec.
Sec .
Sec.
3,
3.
3.
3,
3
3
3
3
,6,
6.
,6.
.6
.6
.6
.6
.6
.1
.2
.3
.4
.5
.6
.7
.8
3-2
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This value was selected because a solids content of 20% is required for
sludges codisposed in municipal landfills and because most types of sludge
landfills commonly take sludges with solids contents of about 20% Table 3-2
presents typical solids contents of sludges disposed in a number of different
types of monofills.
3.1.2 Sludge Storage Capacity
The storage capacity for water in sludge is the moisture content of the
sludge when it has been allowed to drain completely It is defined as the
"dry" water content per square meter (m2) of the sludge under normal
atmospheric conditions.
For the risk model, the storage capacity was set equal to the typical
moisture content of gravity-thickened sludge, that is, 0.90 kg/kg. The
selection of this value is conservative because it represents a high storage
capacity and, thus, a moister sludge. In moister sludges, more water is
available to move through the overburden into the ground water, and pollutants
are more likely to reach ground water faster. Thus, the health and
environmental risks associated with sludges having a high storage capacity are
greater than those for sludges with a low storage capacity.
3.1.3 Sludge Density
Density is defined as the mass of a substance per unit volume. The value
selected for sludge density in the model is 1,025 kg/cubic meter (m3), which
represents the sludge's effective density. For sludges, the effective density
is a more appropriate measure of density than density as defined above. The
effective density takes into consideration the physical state (particle size,
3-3
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TABLE 3-2. Typical Sludge Solids Content by Landfill Type
Type of Landfill Percentage of Sludge Solids (%)
Narrow trench 15-28
Wide trench 20
Area fill mound 20
Area fill layer 15
Diked containment 20
Source: EPA, 1978.
3-4
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amount of bound water, degree of flocculation, etc.) and the chemical
composition of the discrete sludge particle as it exists in a sludge mixture.
As the solids content of a sludge increases, the density is even better
described as a bulk density. A bulk density calculation considers the entire
sludge mixture when figuring density. This type of calculation is not
required to determine the density of a sludge with a 20% solids content.
3.1.4 Specific Gravity
The density of the sludge is used to calculate its specific gravity,
which is defined as the ratio of the density of a substance to the density of
a standard substance. The standard substance used to calculate the specific
gravity of the modeled sludge is water, which has a density of 1,000
grams/liter (g/L) under standard conditions of temperature and pressure.
Sludge with low solids content has a density similar to that of water, so its
specific gravity is close to one. As the sludge solids content increases, the
density of the sludge increases because water is displaced with solid
materials that have a higher density than water. The density could decrease,
however, if the water is displaced by solid material with a relatively lower
particle density than water.
The specific gravity of a sludge can be readily determined by simple
procedures such as those presented in Standard Methods for the Examination of
Water and Wastewater (APHA, 1971). This method involves determining the
weight of a given volume of sludge compared to the weight of an equal volume
of distilled water. As noted in Standard Methods, free- and nonfree-flowing
sludges have different densities; free-flowing sludges have effective
densities and nonfree-flowing sludges have bulk densities. These different
types of densities must be taken into account when sludge is analyzed.
The specific gravity of sludge can vary widely depending on the state of
the sludge (e.g., whether it has been settled, thickened, dewatered, dried,
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etc.). Therefore, the conditions under which a sludge was sampled should
always accompany any statement about its specific gravity, and the analytical
characterization methods used to determine the solids content should be
specified.
Measuring sludge density is not a simple task; the specific gravity of
sludge is usually easier to measure than its density. Rather than measuring
density to calculate specific gravity, the models can measure the specific
gravity of the sludge solids to derive the specific gravity of the whole
sludge, which is the reciprocal of the sludge density. The following equation
illustrates this calculation (Eckenfelder and Santhanam, 1981).
rwn + rwn = j_
SGwa[er SG^ SG3
where SG = sludge specific gravity
WP = weight percentage
1/SGS = sludge density
In the case of the sludge being defined here, which has a 20% solids content
a specific gravity of 1.139 for the sludge solids (chosen to represent a
typical value for the modeled sludge) produces the following:
0.8 + 0.2 = 1
1.0 1.139 1.025
[2]
This calculation shows the derivation of the 1.025 kg/nr density defined in
Section 3.1.3. /
3-6
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3.2 GENERAL HYDROLOGIC PARAMETERS
The model requires a number of inputs that define the general hydrologic
conditions of the hypothetical site. These inputs include net recharge, depth
to ground water, aquifer thickness, and groundwater pH (relative hydrogen ion
concentration) and Eh (oxidation-reduction potential) These parameters are
discussed in the following sections, and the values selected for use in the
model are presented.
3.2.1 Net Recharge
The primary source of ground water is precipitation, which infiltrates
through the ground surface and percolates to the water table. Net recharge is
the amount of water per unit of land that penetrates the ground surface and
reaches the water table. Consequently, recharge water is available to
transport a contaminant vertically to the water table and horizontally within
the aquifer. The recharge rate, which is the amount of recharge per year
(yr), controls the quantity of water available for dispersion and dilution of
contaminants. Recharge is thus a principal vehicle for leaching and
transporting solid or liquid contaminants to the water table. The greater the
recharge rate, the greater the potential for pollution, up to the point at
which the amount of recharge is large enough to dilute the contaminant. At
this point, the pollution potential ceases to increase and may actually
decrease (EPA, 1985b).
For modeling purposes, the recharge value was set to the highest rate of
net infiltration known to occur, 0.5 m/yr, based on information from the
Hazardous Waste Management System Land Disposal Restrictions Regulation (51 FR
1602, January 14, 1986) The highest rate of net infiltration was chosen as
most conservative because, as discussed previously, pollutants are more likely
to reach ground water and travel at a faster rate when the rate of recharge is
greater.
3-7
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3.2.2 Depth to Ground Water
The depth to ground water is generally defined as the depth from the land
surface (or the lowest point of the landfill) to the water table. The water
table is the subsurface interface between the unsaturated zone (where the pore
spaces are filled with water and air) and the saturated zone beneath (where
all the pore spaces are filled with water) ; it may be present in any type of
media and may be either permanent or seasonal. Most saturated zones are
termed aquifers unless they lack the permeability to yield sufficient water.
Only true aquifers are considered when computing depth to ground water.
The depth to ground water is important in evaluating the likelihood that
pollutants moving through the unsaturated soil will reach the ground water.
It also determines the distance that a contaminant must travel before reaching
the aquifer, and it may help to determine the amount of time during which the
contaminant maintains contact with the surrounding media. These factors
influence the amount of attenuation that may occur as the pollutants are
transported. Attenuation processes lessen the amounts or deleterious effects
of contaminants. The factors that affect attenuation are the physical and
chemical processes and properties that include density; solubility, sorption,
biodegradation, oxidation-reduction, dilution, hydrolysis, dispersion,
viscosity, mechanical filtration, ion exchange, volatilization, and buffering
or neutralization. As depth to ground water increases, the degree of
attenuation tends to increase, leading to a decrease in pollution potential.
To identify a suitable value for depth to ground water in the model, eight
landfills were monitored throughout the United States, and depths to the
ground water below them were compiled (EPA, 1977b). A typical depth to ground
water of 5 m was observed among these landfills. A value of 0 m for Class I
ground waters was chosen to model a worst-case depth to ground water. This
conservative value, which represents a situation where the bottom of the
landfill is occasionally or regularly below the water table, is used to
provide the maximum protection to these most sensitive ground waters when
3-8
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determining allowable sludge contaminant concentrations. The 1-m value is
used to represent the depth to all other ground waters, since this depth is
believed to be the minimum distance necessary to provide adequate protection
to human health and the environment while reflecting a reasonable worst-case
scenario.
3.23 Aquifer Thickness
A value of 15 m was chosen as a reasonable aquifer thickness for three
reasons. First, a very small thickness (under 3 m) will have influences in
the model beyond simple mixing and dilution. In aquifers of this size, the
leachate could constitute a large portion of the mixture, thereby nullifying
one of the basic assumptions of the groundwater model, i.e., that leachate
makes up a small portion of the total aquifer. Second, mixing does not
increase with depth beyond about 15 m. Finally, the sensitivity analysis
showed that when mixing beyond 15 m was modeled, no significant (i.e., order
of magnitude) difference in the allowable contaminant levels in sludge were
calculated. (See Section 4 for results and discussion of sensitivity
analyses.)
3.2.4 Groundwater pH
The pH of a solution denotes the negative log of the hydrogen ion
concentration of that solution. In general, the lower the pH, the greater the
solubility of metals. The lowest pH examined in the MINTEQ simulations, 6
standard units (su), is therefore chosen as the most conservative value. (See
discussion of MINTEQ in Section 2.)
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3.2.5 Groundwater Eh
The measure of oxidation-reduction potential, Eh, indicates the potential
of a solution to transfer electrons from the oxidant to the reductant. The
higher the Eh value, the more readily metals migrate. The highest value of Eh
examined in the MINTEQ simulations, 500 millivolts (mv), was chosen as the
most conservative value.
3.3 UNSATURATED ZONE PARAMETERS
The unsaturated zone is the zone where the soil pore spaces are filled
with water and air, distinguishing this zone from the saturated zone, where
pore spaces are filled only with water. A number of soil types and conditions
must be defined for the unsaturated zone as part of the transport modeling.
These parameters are defined in the following sections.
3.3.1 Unsaturated Zone Soil Type
Soil type in the unsaturated zone has a significant impact on the amount
of recharge that can infiltrate into the ground and hence on the ability of a
contaminant to move vertically into the aquifer. Additionally, the
attenuation processes of filtration, biodegradation, sorption, and
volitilization that can take place in the unsaturated zone depend on the soil
type. The quantity of organic material (F^) present in the soil may also be
an important factor for attenuation. In general, the pollution potential of a
soil is largely affected by the type of clay present, the shrink/swell
potential of that clay, and the grain size of the soil; that is, the less the
clay shrinks and swells and the smaller the grain size of the soil, the less
the pollution potential associated with the soil. Soil types in the
unsaturated zone in order of increasing pollution potential are
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(1) nonshrinking clay, (2) clay loam, (3) silty loam, (4) loam, (5) sandy
loam, (6) shrinking clay, (7) sand, (8) gravel, and (9) thin or absent soil
(EPA, 1985a).
Sand has been selected as the modeled soil type for two reasons. First,
Gerritse et al. (1982) used sand as a soil type when measuring the
partitioning of elements between soil and a sewage sludge solution phase.
These partitioning measurements (i.e., Kj values, or distribution
coefficients) are considered the best available for the analysis of metal
transport from landfilled sludge. The same soil type is also used for
nonmetals for convenience and consistency of analysis. Second, sand is one of
the soil types with the highest pollution potential and, as such, serves as a
reasonable worst-case soil.
33.2 Unsaturated Zone Thickness
The unsaturated zone thickness is important in determining how long it
takes contaminants to reach the aquifer, i.e., contaminant travel time. The
longer the travel time, the greater the chance that attenuation processes may
act on the contaminants. The degree of attenuation that occurs depends on
(1) the length of time that the contaminant is in contact with the material
through which it passes; (2) the grain size of the material through which it
passes; (3) the physical and chemical characteristics of the material through
which it passes; and (4) the distance that the contaminant has traveled. For
most contaminants, a greater degree of attenuation is associated with longer
travel times, greater media surface areas, and greater contaminant travel
distances. In general, therefore, as the thickness of the unsaturated zone
decreases, the pollution potential increases.
The thickness of the unsaturated zone over Class I ground water has thus
been chosen as 0 m, a conservative but reasonable worst-case scenario for
sensitive ground water. A value of 1 m has been chosen to represent the case
of a landfill over other groundwater classes. This value is considered to
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represent a reasonable worst-case scenario for these less-sensitive
groundwater types.
Only one unsaturated layer is assumed in these reasonable worst-case
scenarios. Therefore, the thickness of the layer and the depth to ground
water are the same and vary only with the underlying groundwater
classification.
3.3.3 Slope of the Soil Moisture Retention Curve
The slope of the soil moisture retention curve is also called the slope of
the curve plotting matric potential versus moisture content. The matric
potential is a pressure potential that arises from the interaction of water
with the matrix of solid particles in which it is embedded. It is also
associated with water retention by the soil matrix. Water added to soil is
subject to forces of capillary and surface adsorption that vary with water
content (Marshall and Holmes, 1979).
The value of the slope of the soil moisture retention curve has been set
at 4. This value is the typical value for sand, as can be seen in Table 3-3,
which presents a range of slopes for the soil moisture retention curve.
3.3.4 Effective Porosity of the Unsaturated Zone
Porosity is the ratio of the void volume of a given soil or rock mass to
the total volume of that mass. If the total volume is represented by VT, the
volume of the solids by Vs, and the volume of the voids by Vv, then the
porosity, n, is defined as VV/VT. It is usually reported as a decimal
fraction or as a percentage and ranges from 0 (no pore space) to 1 (no solid)
(Freeze and Cherry, 1979). The porosity of a uniform porous medium is largely
function of particle size. For soil types with small particle sizes such as
a
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TABLE 3-3. Typical Values for the Slope of the
Soil Moisture Retention Curve by Soil Type
Soil Texture Slope
Clay 11.7
Silty clay 9.9
Silty clay loam 7.5
Clay loam 8.5
Sandy clay loam 7.5
Sandy silt loam 5 4
Silty loam 4.8
Sandy loam 6.3
Loamy sand 5.6
Sand 4
Source: Hall et al. (1977).
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clay, porosity increases to a maximum of around 50%. Porosities of coarser
media like gravel decrease to a minimum of around 30%. These measured ranges
of porosities suggest a strong correlation with mean particle diameter.
The term effective porosity refers to the amount of interconnected pore
space available for fluid flow and is also expressed as a ratio of voids to
total volume. The effective porosity is identical to porosity for many
unconsolidated porous media and for many consolidated rocks (Todd, 1980) .
The porosity value representative of coarse and medium sand is 0.39 m/m .
For fine sand, this value is 0.43 m3/m3 (Todd, 1980). The lower value of 0.39
m3/m3 was chosen both as most representative of the modeled soil type and as
most conservative.
3.3.5 Bulk Density in the Unsaturated Zone
The bulk density of soil is defined as the mass of dry soil divided by its
total (or bulk) volume. Bulk density directly influences the retardation of
solutes and is related to soil structure. In general, as soils become more
compact, their bulk density increases. This relationship produces a
dependency between porosity and bulk density. Freeze and Cherry (1979) note
that the porosity is equal to one minus the ratio of bulk density to particle-
size density The particle density of soil materials varies over a very
narrow range and can be fixed at a value of 2.65 g/cubic centimeter (cm3)
(Freeze and Cherry, 1979) If particle density is assumed equal to 2.65
g/cm3, the bulk density can be expressed in terms of porosity as follows:
Pb = 2.65 (1 - 9) (3)
where Pb = bulk density, g/cm3
9 = porosity
3-14
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For modeling purposes, bulk density values were obtained from the
literature; the value chosen for the unsaturated zone, 1,400 kg/m3, is a
common value for sand.
33.6 Saturated Soil Hydraulic Conductivity
Unsaturated soil becomes saturated as water or leachate passes through it
to the saturated zone below. Thus the hydraulic conductivity of the
unsaturated zone must be estimated for those times when this zone becomes
saturated. Hydraulic conductivity refers to the ability of the soil or
aquifer materials to transmit water, which in turn controls the rate at which
ground water will flow through soil or an aquifer under a given hydraulic
gradient. The rate at which ground water flows also controls the rate at
which a contaminant will move away from the point at which it enters the soil
or aquifer. Hydraulic conductivity is governed by the amount and
interconnection of void spaces in the soil or aquifer. These voids may occur
as a consequence of intergranular porosity, fracturing, or bedding planes. In
general, high hydraulic conductivities are associated with high pollution
potential.
Saturated soil hydraulic conductivity (K^) is estimated from the
representative values for saturated hydraulic conductivity in Freeze and
Cherry (1979). The value chosen to represent the model landfill site is
10,000 m/yr, which is set at the high end of the hydraulic conductivity scale
for clean sand.
3.4 SATURATED ZONE PARAMETERS
The saturated zone, with its water-filled pore spaces, is in most cases
considered an aquifer. A number of parameters must be defined for the
saturated zone when modeling pollutant transport. These parameters, which
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include soil type, soil hydraulic conductivity, effective porosity, hydraulic
gradient, zone hydraulic conductivity, and bulk density, are discussed below.
3.4.1 Saturated Zone Soil Type
In the saturated zone, the soil type exerts the major control over the
route and path length that a contaminant must follow. The path length is an
important control (along with hydraulic conductivity and gradient) in
determining the time available for attenuation processes such as sorption,
reactivity, and dispersion. It is also important in determining the amount of
effective surface area of the materials contacted by a contaminant in the
aquifer. In general, larger grain sizes and more numerous fractures or
openings within the aquifer are associated with higher permeabilities and
lower attenuation capacity and, consequently, a greater pollution potential.
Soil types in the saturated zone in order of increasing pollution potential
are: (1) massive shale; (2) metamorphic/igneous; (3) weathered
metamorphic/igneous; (4) bedded sandstone, limestone, and shale; (5) massive
sandstone; (6) massive limestone; (7) sand and gravel; (8) basalt; and
(9) Karst limestone (EPA, 1985a). For the same reasons as discussed in
Section 3.3.1, sand has been chosen to represent a reasonable worst-case soil
type.
3.4.2 Effective Porosity in the Saturated Zone
Effective porosities for general hydrogeologic classifications are
presented in Table 3-4. The value of 0.1 m3/m3 has been chosen to represent
the effective porosity in the saturated zone. See the discussion of effective
porosity in Section 3.3.4 for additional information on this parameter.
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TABLE 3-4. Effective Porosities for General
Hydrogeologic Classifications
Effective
Hydrogeologic Classification Porosity
Fractured crystalline silicates 0.01
Fractured and solutioned carbonates 0.10
Porous carbonates 0.10
Porous silicates 0.01
Porous unconsolidated silicates 0.16a
Fractured shale 0.01
aAverage value.
Source: Shafer et al. (1984)
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3.43 Hydraulic Gradient in the Saturated Zone
The hydraulic gradient is, in general, a function of the local
topography, the groundwater recharge volumes and locations, and the influence
of withdrawals (e.g., well fields). It is also very likely to be indirectly
related to porous media properties. Rarely are large gradients associated
with very high conductivities. No functional relationship exists, however, to
express this association.
The hydraulic gradient value selected for use in the model is 0.005 m/m
and is based on an average value of a number of ground waters surveyed for the
Hazardous Waste Management System Land Disposal Restrictions Regulation (51 FR
1602, January 14, 1986).
3.4.4 Bulk Density in the Saturated Zone
Bulk density values are obtained from the literature and the value chosen
for the saturated zone, 2,390 kg/m3, is a common value for sand. More
information on the derivation of bulk density is presented in Section 3.3.5.
3.4.5 Saturated Zone Hydraulic Conductivity
The saturated zone hydraulic conductivity reflects the ease with which
water is transported through porous media. For any given fluid, the hydraulic
conductivity is a function of properties such as particle size, grain shape,
connectivity, and tortuosity, which affect the porosity of the medium.
Individual, site-specific measurements for hydraulic conductivity are usually
difficult to make, and the spatial variability of "point" measurements is the
subject of much current research.
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In addition to porosity, saturated zone conductivity is related to the
velocity of ground water and the hydraulic gradient. The velocity of ground
water is a major determinant of solute transport in subsurface systems; in
uniform, porous media, it is the dominant factor. Groundwater flow velocities
vary widely. Mackay et al. (1985) report that velocities typically range
between 1 to 100 m/yr. These ranges apply to typical ''natural gradient"
conditions, but higher velocities can exist under both induced situations
(e.g., well-field drawdown) and extreme natural situations. For example,
velocities in excess of 9,000 m/yr have been reported for a glacial outwash
material (Guven et al., 1984).
Velocities are related to soil properties and other site-specific factors
through Darcy's law. When Darcy's law and assumptions of steady flow in
uniform, saturated media are used, the following expression for average pore
velocity V is produced:
V = Ks x S (4)
6
where V = velocity of ground water, m/yr
K, = saturated zone hydraulic conductivity, m/yr
S = hydraulic gradient
8 = porosity
This equation can be rearranged as K, = 9V/S to derive the hydraulic
conductivity. The saturated zone hydraulic conductivity was calculated based
on a worst-case groundwater velocity of 100 m/yr, which was determined from
the sensitivity analysis discussed in Section 4. Given a velocity, V, of 100
m/yr, a hydraulic gradient of 0.005 (see 3.4.4), and a saturated zone
effective porosity of 0.1 m3/m3 (see 3.4.3), the saturated zone hydraulic
conductivity for the model is calculated to be 2,000 m/yr.
3-19
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3.5 SURFACE PARAMETERS
Several other miscellaneous parameters must also be defined for the
model: the landfill site geometry, the distance to site boundaries, the
surface wind velocity, the air temperature, the porosities of cover soil, and
the cover thickness. These parameters and assigned values are discussed
below.
3.5.1 Landfill Site Geometry
Table 3-5 presents the geometry used to model the landfill site. The
landfill width and length represent the square root of the average area of
landfills examined for the Hazardous Waste Management System Land Disposal
Restrictions Regulation (51 FR 1602, January 14, 1986). The fill height and
cell length are representative values for landfills.
3.5.2 Distance to the Property Boundary
Within the landfill property, the owner/operator can exercise control to
ensure that there will be no exposure to pollutants at concentrations greater
than the health effects levels. This area is thus known as the area of
effective control. The area of effective control is considered to end at the
point of potential exposure, which for Class II aquifer analysis is defined as
the property boundary. The modeled pollutant concentrations do not exceed
the health effects level at this point when the model has calculated the
maximum allowable contaminant concentrations in the sludge.
To determine an appropriate distance that would represent the point of
potential human exposure, the Agency surveyed 163 Part B hazardous waste land
disposal permit applications available to EPA as of October 1984. Based on
3-20
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TABLE 3-5. Landfill Site Geometry
Parameter Value (m)
Landfill width 100
Landfill length 100
Cell length 8
Fill height 3.46
3-21
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this information, the Agency believes that 150 m is a reasonable, conservative
estimate of the point of effective potential human exposure.
3.53 Surface Wind Velocity
A value of 1 m/sec has been selected to represent a reasonable value for
surface wind velocity. For site-specific modeling, more exact calculations
may be made with values obtained from local weather stations or measured on
site (Tucker and Preston, 1984).
3.5.4 Air Temperature
An air temperature of 15°C has been selected as a reasonable value. The
value could be measured on site or taken from local weather stations for a
more exact calculation when site-specific modeling is performed.
3.5.5 Air-filled Porosity of Cover Soil
It is assumed that cover soils will be drained to field capacity, which
is the water content found when a thoroughly wetted soil has drained for about
2 days. Under this assumption, the air-filled porosity is set equal to the
effective porosity, or 0.1 m3/m3.
3.5.6 Total Porosity of Cover Soil
A value of 0.4 m3/m3 has been chosen as representative of a soil cover of
sand, a worst-case scenario.
3-22
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3.5.7 Cover Thickness
The thickness of the active cover has been set at 0.3 m; the thickness of
the final cover has been set at 1 m. These values are minimal values and are
used to represent worst-case conditions.
3.6 CHEMICAL-SPECIFIC PARAMETERS
A number of chemical-specific factors must be quantified before being
input to the model. These factors include the concentration of contaminants
in the sludge by dry weight basis; the concentration of contaminants in the
leachate; the distribution coefficient; the saturated and unsaturated zone
decay rate; the background concentration of contaminants, and other factors.
The chemical-specific parameters and the values assigned to them are discussed
below.
3.6.1 Concentrations of Contaminants in Sludge
The concentrations of contaminants in the modeled sludge are presented in
Table 3-6. In many cases, the values were taken from 95th percentile values
obtained from a survey of 40 publicly owned treatment works (EPA, 1982) The
values used for chlordane, lindane, DDT/DDD/DDE, trichloro-ethylene, and
toxaphene, however, were the maximum values reported. Other values were
derived as noted in the table. These values were used to begin the Iterative
runs as a first approximation (see Section 2)
3.6.2 Concentrations of Contaminants in Sludge Leachate
The concentrations of contaminants in the modeled sludge leachate are
presented in Table 3-7 Most of these values were derived using the modeled
3-23
-------
TABLE 3-6. Concentrations of Contaminants in Sludge (dry weight)
Parameter Concentration (mg/kg)
Arsenic 2°'75a
Cadmium 88.133
Copper 5600
Lead 1070
Mercury 5.85
Nickel 920
Benzene 6.6
Benzo(a)pyrene 1.935
Bis(2-ethylhexyl)phthalate 459
Chlordane 12
DDT/DDD/DDE 0.930
Dimethylnitrosamine 0.272
Lindane 0.220
Polychlorinated biphenyls 2.90
Trichloroethylene 17.85
Toxaphene 10.8
aThe value was obtained by averaging the maximum values reported by a number
of surveys.
bThe value was the mean value reported in EPA (1982) .
Source: EPA (1982), except as noted.
3-24
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TABLE 3-7. Concentrations of Contaminants in Sludge Leachate
Parameter Concentration (mg/L)
Arsenic 1 a
Cadmium 0.2b
Copper 37 b
Lead 10 b
Mercury 0.69C
Nickel 3 4d
Benzene 0.12
Benzo(a)pyrene 0.000006
Bis(2-ethylhexyl)phthalate 25 a
Chlordane 0.00014
DDT/DDD/DDE 0.01e
Dimethylnitrosamine 0.014
Lindane 0.00039
Polychlorinated biphenyls 0.0000018
Trichloroethylene 0.022
Toxaphene 0.15
"The value is based on an estimated liquid concentration that
requires at least one year to deplete the mass of the leachate in
the sludge.
'"The value was the maximum reported for leachate from a
sludge monofill (EPA, 1978).
cThe value was recommended by Betsy Southerland (1987)
dThe value was the maximum effluent reported for municipal
wastewaters. (Earth et al., 1965)
eThe value was the maximum effluent value reported (EPA,
1978)
Source: Calculated from Koc and the values in Table 3-6, except
as noted.
3-25
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sludge concentrations in Table 3-6 and the organic carbon content of the soil
(K.J "at 5% total solids and 50% organic solids. The sources of other values
are as noted in the table. These values were used to begin the iterative runs
as a first approximation.
3.6.3 Distribution Coefficient
Contaminant transport in soil systems is directly related to
contaminant/soil interactions. The affinity that soil particles have for
contaminants may result from ion exchange on charged sites or adsorption due
to surface forces. When that capacity is exceeded, soluble contaminants will
move through the soil at the same velocity as the bulk leachate. The affinity
between a soil and a contaminant, and therefore a soil's capacity to hold a
contaminant, is characterized by the distribution coefficient K,-,.
Representative K
-------
TABLE 3-8. Distribution Coefficients, K,
Parameter Coefficient (L/kg)
Inorganic
Arsenic
Cadmium
Copper
Lead
Mercury
Nickel
5.
14.
41.
234
322
12.
.86
,9
.9
2
Organic
Benzene 0.0074
Benzo(a)pyrene 550
Bis(2-ethylhexyl)phthalate 200000
Chlordane 17
DDT/DDD/DDE 500
Dimethylnitrosamine 0 000004
Lindane 0.108
Polychlorinated biphenyls 32
Trichloroethylene 0.0198
Toxaphene 0.06
"Based on an f^ of 10"4 x KO,. (see text) .
3-27
-------
where K^ = organic carbon content of the soil
fx = fraction of soil consisting of organic matter
If the values for K^ have not been determined experimentally, equations
are available to estimate them from octanol-water partition coefficient data,
known as K^ or solubility.
For organic contaminants, Kj is a function of organic content in soil.
The value of ICT* was selected for the fx values as a typical value for sand.
It is assumed that subsoils in the aquifer will not contain organic matter
and, therefore, the Kj for organics in the saturated zone is set equal to
zero.
3.6.4 Saturated and Unsaturated Zone Decay Rate
Reductions in pollutant concentrations due to degradation processes such
as hydrolysis and biochemical oxidation are characterized by a degradation
constant, or decay rate, which is related to the time required for the
contaminant concentration to be reduced to one-half its initial value. (See
Section 2 for more details.) The values used in the model to represent the
saturated and unsaturated zone decay rates are presented in Table 3-9.
3.6.5 Background Concentrations of Contaminants
The background concentrations of contaminants in ground water were taken
from "Significance of Properties and Constituent's Reported in Water Analysis'
(Hen, 1985) and are presented in Table 3-10. Where explicit values were not
3-28
-------
TABLE 3-9. Saturated and Unsaturated Zone Decay Rates
Parameter Decay Rate (yr"1)
Arsenic 0
Cadmium 0
Copper 0
Lead 0
Mercury 0
Nickel 0
Benzene 0
Benzo(a)Pyrene 0
Bis(2-ethylhexyl)phthalate 0
Chlordane 8.43a
DDT/DDD/DDE 0.904b
Dimethylnitrosamine 607 . Oa
Lindane 8.43C
Polychlorinated biphenyls 0
Trichloroethylene 0.904d
Toxaphene 0
aThis value was obtained from EPA's Athens Environmental
Research Laboratory (Kollig)
bThis value was taken from Wolf et al. (1977)
°rhis value was taken from Raghu and MacRae (1966)
dThis value was taken from Kleopfer (1985)
Sources: As noted above.
3-29
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TABLE 3-10. Background Concentrations of Contaminants
Parameter Concentration (mg/L)
Arsenic 0.0004
Cadmium 0.001
Copper 0.01
Lead 0.001
Mercury 0.0003
Nickel . 0.0027
Benzene 0
Benzo(a)pyrene 0
Bis(2-ethylhexyl)phthalate 0
Chlordane 0
DDT/DDD/DDE 0
Dimethylnitrosamine 0
Lindane 0
Polychlorinated biphenyls 0
Trichloroethylene 0
Toxaphene 0
3-30
-------
given, values were estimated from this source. Since metals are ubiquitous,
they can be expected to be found naturally in ground waters. Organics,
however, are not expected to be found in noncontaminated ground waters and,
therefore, the background concentrations of organics were set to zero
3.6.6 Health Effects Levels
The health effects level (HEL, in mg/L) is defined as a groundwater
concentration used to evaluate the potential for adverse effects on human
health as a result of sludge landfilling. The monofill pollutant limits that
represent allowable contaminant concentrations in sludge to be monofilled,
which are presented in §503.43 of the Sewage Sludge Technical Regulations,
were calculated to result in groundwater concentrations below the HEL at the
point of compliance. The point of compliance is the property boundary for
Class II aquifer analysis, but is the point at which leachate enters the
aquifer for Class I aquifer analysis. (See Section 2.3 for a definition of
these two types of analyses.)
The HEL values, presented in Table 3-11, are set equal to Maximum
Contaminant Levels (MCLs) where they are available. Where KCLs are not
available, a HEL is calculated based on Risk Reference Doses (RfDs) for
threshold-acting contaminants, (i.e., noncarcinogens) or q:* values for
carcinogens. The RfD is a benchmark dose for noncarcinogens derived from the
no-observed-adverse-effects level (NOAEL) by applying generally order-of-
magnitude uncertainty factors (UFs). These UFs reflect various types of data
used to estimate RfDs and an additional modifying factor (MF), which is
derived based on professional judgment following review of the contaminant's
entire data base. In general, the RfD is an estimate (with uncertainty
spanning perhaps an order of magnitude) of a daily exposure to the human
population (including sensitive subgroups) that is very likely to result in no
appreciable risk of health effects during a lifetime. The RfD is
appropriately expressed in units of mg/kg-body weight (bw)/day The HEL was
calculated from the RfD using the following equation:
3-31
-------
TABLE 3-11. Health Effects Levels (mg/L)
Parameter
Concentration (mg/L)
Arsenic
Cadmium
Copper
Lead
Mercury
Nickel
Benzene
Benzo(a)pyrene
Bis(2 -ethylhexyl)phthalate
Chlordane
DDT/DDD/DDE
DimethyInitrosamine
Lindane
Polychlorinated biphenyls
Trichloroethylene
Toxaphene
0.05a
0.01"
1.3a
0.05a
0.0023
1.75"
0.005a
0.00003C
0.0248C
0. 00021°
0.00102°
o.oooor
0.004a
0.0000454°
0.005a
0.0005"
aThe value is a Maximum Contaminant Level (MCL) under the
Safe Drinking Water Act (SDWA)
bThe value is calculated from a risk reference dose (RfD)
established by EPA's Office of Research and Development.
°The value is calculated from a q:* value representing a
maximum allowable dose for carcinogens at the 10"5 level.
Sources: As noted above.
3-32
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HEL = RfD x BW (6)
where RfD = reference dose (mg/kg/day)
BW = human body weight (kg)
Iw = water ingestion rate (L/day)
The human body weight was set at 70 kg and the water ingestion rate at
2 L/day for adults, standard values used by EPA.
For most carcinogenic chemicals, the linearized multistage model is
recommended for estimating human cancer potency from animal data (49 FR
46298) When epidemiological data are available, potency is estimated based
on the observed relative risk in exposed versus nonexposed individuals and on
the magnitude of exposure. Guidelines for using these procedures have been
presented in the Federal Register (45 FR 79350-47353; 50 FR 46294-46301) and
in each of a series of health assessment documents prepared by the Office of
Health and Environmental Assessment (OHEA). The potency value, qf~ normally
used in risk assessments, is the upper-bound estimate of the slope of the
dose-response curve in the low-dose range. This value is expressed in terms
of risk per dose, where dose is expressed in units of mg/kg/day Thus, qt* is
expressed in units of mg/kg/day"1 The HEL was calculated from q:* using the
following equation:
HEL - fRL x BW)/q.* (7)
L
where RL = risk level
BW = human body weight (kg)
Iw = water ingestion rate L/day)
As in the RfD computation, the human body weight was set at 70 kg and the
water ingestion rate at 2 L/day for adults; the risk level (qf*) was set
at 10'5.
3-33
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3.6.7 Molecular Weight
The values presented in Table 3-12 are standard molecular weights for
several contaminants of concern. These weights are used in the vapor loss
simulations and have been "hard-wired" into the model.
3.6.8 Henry's Law Constants
Henry's law constants are used to calculate the vapor loss of contaminants
from sludge and are "hard-wired" into the model. Table 3-13 presents
constants for several contaminants of concern. The values for benzo(a)pyrene
and bis(2-ethylhexyl)phthalate were calculated from vapor pressure and
solubility data that are maintained in the Henry's law database at Research
Triangle Park, using the procedures in Mackay and Shui (1981) The vapor
pressure of bis(2-ethylhexyl)phthalate was calculated from boiling points at
various pressures using Antoine's equation and the solubility data was
obtained from Verschueran (1983). The value for chlordane was also obtained
from the database, but was taken from Hwang (1982). Values for DDT/DDE/DDD
and polychlorinated biphenyls (PCBs) were taken from Lyman et al (1982)
Finally, the value for dimethyInitrosamine was taken from Dawson et al.
(1980) .
3-34
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TABLE 3-12. Standard Molecular Weights for Modeled Pollutants
Contaminant Molecular Weight
Benzo(a)pyrene 252.32
Bis(2-ethylhexyl)phthalate 391
Chlordane 410
DDT/DDE/DDD 354.5
DimethyInitrosamine 74.08
Polychlorinated biphenyls 300
3-35
-------
TABLE 3-13. Henry's Law Constants for Selected Contaminants
Contaminant Constant
Benzo(a)pyrene 0.000000017
Bis(2-ethylhexyl)phthalate 0.004625
Chlordane 0.002
DDT/DDE/DDD 0.0017
Dimethylnitrosamine 0.02
Polychlorinated biphenyls 0.16
Sources: As noted in text.
3-36
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SECTION FOUR
SENSITIVITY ANALYSIS
In developing the risk assessment methodology for each sludge disposal
option, the Agency selected or created mathematical models that would predict
the average long-term human health and environmental effects of continually
disposing of sludge in the soil and/or water. The SLUDGEMAN model was
developed to predict the maximum allowable pollutant concentrations in sewage
sludge at a landfill site that would not detrimentally affect a Most Exposed
Individual (MEI). The MEI was defined as a person who drinks 2 L of ground
water per day from the site over a 70-yr lifespan.
Existing disposal practices were extensively reviewed to develop
reasonable worst-case values for the site characteristics used in the model.
Six sets of sensitivity analyses were performed on selected model parameters.
The results of these analyses are discussed below and are detailed in
Appendix B.
The eight parameters evaluated for their effect on allowable sludge
concentrations are:
Depth of the soil layer between the landfill and ground water
Organic carbon fraction of that soil layer
Distance to the point of compliance
Groundwater velocity
Aquifer thickness
Net recharge rate
Eh and pH conditions of the ground water
Moisture content of the sludge
4-1
-------
Adsorption and decay coefficients -- parameters specific to each chemical --
were not evaluated in the sensitivity analyses.
Initially, a base-line case scenario was run, against which all subsequent
runs were compared. The input parameters for the baseline case are presented
in Table 4-1.
The sensitivity analyses were performed by holding all parameters at their
baseline value or at other specific values, except the parameter being
evaluated. One parameter, distance to the property boundary, was varied in
all the sensitivity analyses to determine the effect of this variable in
combination with all the other parameters of interest in these analyses.
Because parameter sensitivity depends on the baseline conditions selected
and on the adsorption and decay coefficients assigned, the analysis may not
give a generally applicable measure of sensitivity, but rather a specific
measure applicable to the testing conditions. It is also important to note
that the validity of the sensitivity analysis hinges on the validity of the
model framework itself.
4.1 EFFECT OF SOIL DEPTH AND CARBON CONTENT
The first set of sensitivity analyses evaluated the effect on maximum
allowable sludge pollutant concentrations of (1) the depth of the soil layer
between the landfill and the ground water and (2) the organic carbon content
of that soil layer. The organic content of the soil was examined because it
influences the amount of organic pollutants that will adsorb onto the soil,
thus not reaching the aquifer. It does not, however, affect metals leaching
to ground water Depth to ground water proved to be an extremely sensitive
parameter for DDT, lindane, and bis(2-ethylhexyl)phthalate (BEHP), as will be
discussed in the following sections.
4-2
-------
TABLE 4-1. Input Parameters for the Baseline Case
Parameter
Volume
Depth to ground water
Net recharge rate
Groundwater gradient
Hydraulic conductivity of
saturated zone
Groundwater velocity
Aquifer mixing thickness
Eh and pH
Sludge moisture content
Sludge storage capacity
Sludge density
Width of landfill
Length of landfill
Height of fill
Aquifer width
0 m
0.5 m/yr
0.005 m/m
2,000 m/yr
100 m/yr
15 m
+500 mv/6.0
0.80 kg/kg
0.90 kg/kg
1,025 kg/m3
100 m
100 m
3.46 m
1,000 m
4-3
-------
4.1.1 Results for Class I Aquifers
For Class I ground waters, as described in Section 2, human health
criteria must be met at the point where the leachate first enters the aquifer.
Thus, the location of the landfill property boundary is not a factor in the
analysis. Table 4-2 presents the results of the analyses for Class I
aquifers. When a low soil organic carbon content of 0.0001 is assumed, as
depth to ground water increases from 0 to 1 meter (m) , the maximum allowable
concentrations increase for all the regulated pollutants by less than an order
of magnitude. For soils with a high organic carbon content of 0.01, as depth
to ground water increases from 0 to 1m, the allowable sludge concentrations
increase by two orders of magnitude for DDT and by three orders of magnitude
for lindane. In other words, leachate from landfills with sludges containing
the maximum allowable concentrations of these pollutants calculated by these
sensitivity analyses would still meet the human health criteria at the point
where the leachate first enters the aquifer.
For soils with an organic content of 0.0001, as the depth to ground water
increases to 5 m, allowable sludge concentrations for DDT increase by one
order of magnitude. When an organic soil content of 0.01 m is assumed, as
depth to ground water increases to 5 m, allowable sludge concentrations
increase by one order of magnitude for BEHP, two orders of magnitude for DDT,
and three orders of magnitude for lindane.
For soils with an organic content of 0.0001, as the depth to ground water
increases to 10 m, the allowable sludge concentrations for DDT and lindane
increase by one order of magnitude. When an organic content of 0.01 is
assumed, the 10-m depth increases allowable sludge concentrations by one order
of magnitude for BEHP and by three orders of magnitude for DDT and lindane.
4-4
-------
TABLE 4-2. Effect of Soil Depth and Organic Carbon Content
on Maximum Allowable Sludge Pollutant
Concentrations for Class I Aquifers
Depth of Soil
Between Landfill
and Aquifer
Soil
Organic
Carbon Content
Pollutant
Orders of
Magnitude of
Increase in
Maximum Allowable
Sludge Pollutant
Concentrations
over Baseline
1-m
1-m
0.0001
0.01
All regulated
pollutants
DDT
Lindane
Less than 1
5-m
5-m
0.0001
0.01
DDT
BEHP
DDT
Lindane
10-m
0.0001
DDT
Lindane
10-m
0.01
BEHP
DDT
Lindane
4-5
-------
4.1.2 Results for Class II Aquifers
For Class II ground waters, human health criteria must be met'after the
leachate mixes with the ground water and is transported to the property
boundary of the landfill where water supply wells might be constructed. The
property boundary of the landfill is, therefore, an important parameter in the
analysis of Class II aquifers. The greater the distance from the edge of the
waste management unit to the property boundary, the greater the allowable
sludge concentrations because pollutants undergo more dilution and decay the
farther they travel in the aquifer.
The sensitivity analyses of landfill model parameters were performed
assuming property boundary locations at 50 m, 150 m, 500 m, and 1,000 m from
the landfill. The results are given in Table 4-3. For the 50-, 150-, and
500-m boundaries, a 0.0001 soil organic carbon content caused an order-of-
magnitude increase in only one pollutant, DDT, at both the 1 and 5-m soil
depths, compared to the baseline of 0-m. When a 0.01 soil organic carbon
content was assumed, the maximum allowable pollutant concentrations of three
pollutants, DDT, BEHP, and lindane, increased significantly at both the 1- and
5-m soil depths for all three boundaries. Significant increases also occurred
for these three pollutants at the 10-m soil depth.
The sensitivity analyses indicate that the 1,000-m property boundary
parameter was very insensitive to the depth of the intervening soil layer.
The 1,000-m distance is so far from -the landfill that allowable sludge
concentrations are controlled by dilution and transformation processes in the
aquifer rather than by processes in the soil layer under the landfill. A 1-m-
deep soil layer caused no significant increase in maximum allowable pollutant
concentrations over reasonable worst-case sludge concentrations. The 5- and
10-m-deep soil layers caused an order-of-magnitude increase in just one
pollutant, BEHP, and that increase only occurred when the soil was modeled
with a high fraction (0.01) of organic carbon content.
4-6
-------
TABLE 4-3. Effect of Soil Depth and Organic Carbon Content
on Maximum Allowable Sludge Pollutant
Concentrations for Class II Aquifers
Orders of
Magnitude of
Increase in
Maximum Allowable
Depth of Soil Location Sludge Pollutant
Between Landfill of Property Soil Organic Concentrations
and Aquifer Boundary Carbon Content Pollutant over Baseline
1-m and 5-m 50-m, 150-m
and 500 -m
1-m and 5-m 50-m, 150-m
and 500 -m
1-m and 5-m 50-m, 150-m
and 500 -m
1-m and 5-m 50-m
150-m
500-m
10 -m
10-m
1-m 1000-m
5-m and 10-m 1000-m
5-m and 10-m 1000-m
5-m and 10-m 1000-m
0.
0.
0,
0,
0,
0.
0,
0,
0.
0
0,
0,
0.
,0001
.0001
.01
.01
.01
.01
.0001
.01
.01
.0001
.0001
.01
.01
DDT
All regulated
pollutants
other than DDT
DDT
BEHP
Lindane
Lindane
Lindane
DDT
Lindane
BEHP
DDT
All regulated
pollutants
All regulated
pollutants
BEHP
All regulated
1
Insignificant
1
1
3
3
1
1
1
1
1
Insignificant
Insignificant
1
Insignificant
pollutants
other than BEHP
4-7
-------
4.2 EFFECT OF RECHARGE RATE
The second set of sensitivity analyses evaluated the effect of recharge
rates on maximum allowable sludge concentrations. The net recharge rate is
the amount of rain water that seeps through the landfill and the underlying
soil into the ground water. It is calculated as the average annual amount of
rainfall minus losses from evaporation to the air and transpiration by plants.
Recharge rate does not affect the maximum allowable pollutant concentrations
in sludge for Class I ground waters. For the Class I analysis, the leachate
itself must meet human health criteria, thus the rate at which the leachate is
added to ground water is not important. For the Class II analysis, however,
the recharge rate has some effect.
The highest national average recharge rate (0.5 m/yr) was assumed for the
baseline case. A high value was chosen because the higher the recharge rate,
the more rapidly the pollutants are flushed into the ground water. The
sensitivity analyses examined lower net recharge values of 0.25 m/yr and
0.00635 m/yr. The 0.25 m/yr recharge rate did not cause a large increase in
the allowable sludge concentrations; the increase was only a factor of two to
three whether the property boundary was set at 50 m, 150 m, 500 m, or 1,000 m.
In contrast, the very low (0.00635 m/yr) recharge rate caused order-of-
magnitude increases in allowable sludge concentrations for both metals and
organics. For Class II ground waters at 50-m and 150-m boundaries, the
0.00635-m/yr recharge rate increased allowable sludge concentrations by three
orders of magnitude for arsenic and cadmium and by one order of magnitude for
the other pollutants. For Class II ground waters at 500-m and 1,000-m
boundaries, the 0.00635-m/yr recharge rate increased allowable sludge
concentrations by two orders of magnitude for cadmium and one order of
magnitude for the other pollutants.
4-f
-------
4.3 EFFECT OF GROUNDWATER VELOCITY
The third set of sensitivity analyses evaluated the effect of groundwater
velocity on maximum allowable sludge concentrations. Groundwater velocity is
a function of gradient and hydraulic conductivity of the groundwater zone.
The baseline groundwater velocity is 100 m/yr based on a gradient of 0.005 m/m
and a hydraulic conductivity of 2,000 m/yr. The sensitivity analysis examined
the effect of raising the groundwater velocity to 1,000 m/yr (based on a
gradient of 0.1 m/m and hydraulic conductivity of 1,000 m/yr) and lowering it
to either 10 m/yr (based on a gradient of 0.005 m/m and hydraulic conductivity
of 200 m/yr) or 1 m/yr (based on a gradient of 0.0001 m/m and hydraulic
conductivity of 1,000 m/yr). Table 4-4 presents the results of these
analyses.
The sensitivity analyses demonstrated that high groundwater velocity
(1,000 m/yr) tends to increase allowable sludge concentrations because it
provides greater dilution of the contaminants as they enter the aquifer. For
degradable organics, however, increased dilution at higher velocities may be
offset by a decrease in travel time to the property boundary, which reduces
the time in which decay can occur before the sludge contaminants reach the
boundary.
Groundwater velocity was generally a relatively insensitive parameter for
all pollutants except cadmium and arsenic. For Class I ground waters, the
variation in groundwater velocity has no effect on maximum allowable sludge
concentrations because human health criteria must be met at the point of
leachate entry into the aquifer, before the leachate is transported in the
aquifer. For Class II ground waters, the high groundwater velocity of 1,000
m/yr caused a large increase in the allowable sludge concentrations for
cadmium and arsenic independent of property boundary location (50 m, 150 m,
500 m, or 1,000 m). The high velocity also increased the allowable sludge
concentrations for the other regulated pollutants, but by lesser amounts At
the 150-m boundary, a one-order-of-magnitude increase in velocity (i.e., 1,000
m/yr) caused a three-order-of-magnitude increase in the allowable arsenic and
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TABLE 4-4. Effect of Groundwater Velocity on Maximum
Allowable Sludge Concentrations
Location
Groundwater of Property
Velocity Boundary
1,000 m/yr 150 -m
10 m/yr 50 -m
10 m/yr 150-m
1 m/yr 50 -m
1 m/yr 150-m
10 m/yr 500 -m
1 m/yr 500-m
10 m/yr 1000-m
1 m/yr 1000-m
Pollutant
Cadmium
Arsenic
DDT
TCE
Lindane
DDT
TCE
Lindane
DDT
TCE
Lindane
DDT
TCE
Lindane
DDT
TCE
Lindane
DDT
TCE
Lindane
All pollutants
All pollutants
Orders of
Magnitude of
Increase in
Maximum Allowable
Sludge Pollutant
Concentrations
over Baseline
3
3
1
2
2
1
3
3
1
3
3
1
3
3
1
1
1
1
1
1
Insignificant
Insignificant
4-10
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cadmium sludge concentrations. This increase is much greater than that which
can be explained by increased dilution.
The lower groundwater velocities of 10 m/yr and 1 m/yr also increased the
allowable sludge concentrations over those calculated for the baseline
situation. The most significant increases were for DDT, lindane, and
trichloroethylene at landfills with 50-m, 150-m, and 500-m boundaries. At the
1,000-m boundary, the lower velocities did not cause significant increases in
allowable sludge concentrations for any pollutants. The effect of groundwater
velocity was reduced at 500 m and 1,000 m because most of the chemical was
already well dispersed and degraded by the time it reached those distances, no
matter what the velocity
4.4 EFFECT OF AQUIFER THICKNESS
The fourth set of sensitivity analyses evaluated the effect of aquifer
thickness, or the depth of an aquifer, on maximum allowable sludge
concentrations. The greater the aquifer thickness, the greater the volume of
water into which the leachate plume may diffuse. Aquifer thickness proved to
be a somewhat sensitive parameter.
The reasonable worst-case situation is based on a relatively small aquifer
thickness of 15 meters. The sensitivity analyses looked at aquifers 78.6 m
and 560 m in depth, as well as at a smaller aquifer of 5 m in depth. Aquifer
thickness does not affect allowable sludge concentrations for Class I ground
waters because human health criteria must be met before the water in the
aquifer dilutes the contaminants. For Class II ground waters where the
property boundary was assumed to be at 50 m, 150 m, or 500 m, the two greater
aquifer thicknesses (78.6 m and 560 m) .caused no significant increase in
allowable sludge concentrations. The smaller thickness (5 m), however, did
decrease the allowable sludge concentration by an order of magnitude.
When the property boundary was assumed to be located at 1,000 m, aquifer
thickness significantly affected the allowable sludge concentrations. At the
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1,000-m boundary, the two thicker aquifers increased allowable sludge
concentrations by an order of magnitude for arsenic and two orders of
magnitude for cadmium. The thinner aquifer decreased allowable sludge
concentrations by one order of magnitude.
4.5 EFFECT OF Eh AND pH
The fifth set of sensitivity analyses examined the effect of ground water
Eh and pH on maximum allowable sludge concentrations. Eh denotes the
potential required to transfer electrons from the oxidant to the reductant,
and pH denotes the negative log of the hydrogen ion concentration. At the
point where leachate enters the ground water, the landfill model reduces
groundwater metal concentrations to the solubility limit of the metal. The
amount of metal that precipitates out of solution depends on the Eh and pH of
the ground water.
Ground water with a high Eh and a low pH will keep most metals in the
dissolved state --a more hazardous situation. The reasonable worst-case
values are an Eh of +500 millivolts (mv) and a pH of 6 standard units (su).
Ground water with a low Eh and a high pH is more likely to cause metals to
precipitate out of solution, so higher metal concentrations can be allowed in
the sludge.
The sensitivity analyses examined the effect of a moderate Eh condition of
+150 mv and a pH of 6, as well as an Eh condition of -200 mv and a pH of 7.
Only the latter Eh and pH conditions had much effect on allowable sludge
concentrations.
For Class I ground waters, an Eh of -200 mv and a pH of 7 caused an
increase in the allowable sludge concentrations of three orders of magnitude
for arsenic, one order of magnitude for copper, and two orders of magnitude
for lead and nickel. For Class II ground waters at a 50-m boundary, this
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condition caused a three-order-of-magnitude increase in sludge concentrations
for arsenic and a one-order-of-magnitude increase for lead.
4.6 EFFECT OF SLUDGE MOISTURE CONTENT
The sixth and final set of sensitivity analyses evaluated the effect of
sludge moisture content on maximum allowable sludge concentrations. The
reasonable worst-case value for sludge moisture content is 80%. Sludges with
higher moisture content were expected to increase allowable sludge
concentrations because they contain a smaller proportion of contaminated
solids. Sludges with lower moisture content were expected to decrease
allowable concentrations because they contain a higher proportion of
contaminated solids. The sensitivity analyses examined the effect of a higher
moisture content (95%) and a lower moisture content (60%).
Sludge moisture content proved to be a relatively insensitive parameter.
For Class I ground waters, use of a 95% moisture sludge did not significantly
increase the allowable sludge concentrations and use of a 60% moisture sludge
did not significantly decrease the allowable sludge concentrations. For Class
II ground waters at 50 m, 150 m, 500 m, and 1,000 m, the analysis showed that
use of a 95% moisture sludge would increase the allowable sludge
concentrations by an order of magnitude, whereas use of a 60% moisture sludge
would decrease allowable sludge concentrations by less than an order of
magnitude..
4-13
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SECTION FIVE
POLLUTANT LIMITS
The proposed 405(d) sewage sludge regulations are based on maximum
pollutant limits that have been calculated for each sludge pollutant evaluated
for this regulation. The Agency selected reasonable worst-case values for
monofill site characteristics (detailed in Section 3) to calculate these
maximum allowable sludge concentrations (pollutant limits) using the
methodology in Section 2. Appendix C discusses methods for determining
site-specific parameters in more detail.
The pollutant limits are set based on the classification of the aquifer
underlying the monofill. The depth to ground water and the "point of
compliance," or the point at which the ground water must meet the health
effects level, vary with the classification of the underlying aquifer. These
classifications, which are defined in Section 2, are discussed below:
If the monofill is located over a Class I aquifer, the depth to ground
water is set at zero and the health effects level must be met at the
edge of the sewage sludge unit (point of compliance)
If the monofill is located over either a Class II or Class III(A2)
aquifer, or a Class III(Al) or Class III(B) aquifer with total
dissolved solids concentrations exceeding 10,000 mg/L, the depth to
ground water is set at 1 m and the health effects level must be met 150
m from the edge of the sewage sludge unit or at the property boundary,
whichever is less (point of exposure)
If the monofill is located over either a Class III(Al) or Class III(B)
aquifer and the background concentration of one or more pollutants in
the ground water exceeds the health effects level for the pollutant(s),
then the depth to ground water is set at 1 m, and the background
concentration of those pollutants must be met 150 m from the edge of
the sewage sludge unit or at the property boundary, whichever is less.
For the regulatory requirements to be met, the pollutant concentrations in
the sludge cannot result in groundwater pollutant concentrations that exceed
the health effects levels for those pollutants (listed in Section 3) unless
the background pollutant concentrations in the ground water exceed those
5-1
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levels. Table 5-1 presents the maximum sludge pollutant concentrations (dry
weight) for each pollutant in mg/kg for two major groups of ground water
types. The first column presents the limits applicable to monofills located
over Class I aquifers. The second column presents the sludge pollutant limits
for monofills located over most other aquifer types. If none of the pollutant
concentrations in a sludge exceed the specified limits for the groundwater
classification of the aquifer underlying the monofill, then the sludge may be
placed in that monofill.
In some instances, the owner/operator cannot or may not want to use the
sludge pollutant limits specified in Table 5-1. First, some monofills may be
located over an aquifer with background concentrations of one or more
pollutants exceeding the health effects levels. When this situation occurs,
the sludge must meet pollutant limits equal to the background concentration of
the underlying aquifer for any pollutants whose concentrations in the aquifer
exceed the health effects levels. Thus sludge pollutant concentrations for
monofills located over this type of aquifer must be set on a case-by-case
basis using the existing background concentrations in the ground water and
back-calculating using SLUDGEMAN (with the reasonable-worst-case values from
tables in Section 3) to generate modified maximum allowable sludge
concentrations.
Second, some monofills located over Class II or III aquifers may have
property boundaries that are less than 150 m from the edge of the unit (thus
the relevant point of compliance is different from that used to derive the
pollutant limits in Table 5-1). In these cases, a set of modified maximum
allowable sludge concentrations must be calculated using the actual boundary
distance as the point of compliance.
Finally, if one or more of the pollutant concentrations in the sludge to
be disposed exceeds the maximum allowable concentrations, then the regulation
allows for certain site-specific parameters to be varied on a case-by-case
basis. The site-specific parameters that the regulation allows to be varied
were selected as those which caused the most significant increase or decrease
in allowable sludge concentrations when the sensitivity analyses were
performed (see Section 4). These sensitivity analyses were run on the
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TABLE 5-1. Maximum Sewage Sludge Concentration
(mg/kg dry weight)
Monofill over
Monofill over Class II/Class III(A2)/
Class I Class III(Al) -Class III(B)a
Pollutant Ground Water Ground Water
Arsenic
Benzene
Benzo(a)pyrene
Bis(2-ethylhexyl)
phthalate
Cadmium
Chlordane
Copper
DDT/DDE/DDD (total)"
Dimethylnitrosamine
Lead
Lindane
Mercury
Nickel
Polychlorinated
biphenyls
Trichloroethylene
Toxaphene
0.20
0.28
97
4.5
0.040
180
8.4
0.95
0.0019
0.35
2.3
0.0070
7
49
4.1
0.36
24
0.
250
1,600
9.
51
0.
530
75
26
49
51
1.
,85
.6
070
,1
aGround water meets definition of either Class III(Al) or Class III(B)
ground water and the total dissolved solids concentration exceeds 10,000
mg/L in the ground water.
"DDT -- Bis l,l-(4-chlorophenyl)-2,2,2-trichloroethane
DDE -- Bis 1,1-(4-chlorophenyl)-2,2-dichloroethylene
ODD -- Bis 1,1-(4-chlorophenyl)-2,2-dicloroethane
5-3
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following parameters: depth to ground water and organic carbon content of the
unsaturated zone; net recharge rates; groundwater gradient and hydraulic
conductivity of the saturated zone; aquifer thickness; Eh and pH of the
saturated zone; and sludge moisture content. The depth to ground water, Eh
and pH of the saturated zone, and net recharge rates were identified in the
sensitivity analyses as the parameters that can be varied on a site-specific
basis. In addition to these parameters, soil type and pollutant partition
coefficient are also allowed to vary. When the standard parameter values are
replaced by these site-specific values, the risk assessment model SLUDGEMAN
generates the set of modified maximum allowable sludge concentrations that
must be met before the sludge can be disposed.
If the sludge concentrations of one or more pollutants exceed the modified
maximum allowable sludge concentrations, then the sludge may not be monofilled
unless the pollutant concentrations in the sludge can be reduced below the
modified maximum allowable levels.
Figure 5-1 shows how pollutant limits, pathogen and vector attraction
reduction requirements, and management practices determine whether sewage
sludge may be monofilled.
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SEWAGE SLUDGE MONOFILL
Sewage Sludge
National Limits Case-by-Case Limits
Distance from sewage sludge
unit boundary to monofill
property One £150 meters.
I
No
Yes
Determine pollutant limits
using actual distance from
sewage sludge unit boundary
to monoflll property line.
Ground water classified as
Class I, Class U or as Class II
due to IDS * 10,000 mg/l or
yield < 150gal/d.
No
Determine pollutant limits
using existing pollutant
concentrations In ground water.
ri
Yes
Determine pollutant limits
from Table 5.
Yes
No
Comply with pollutant Omits.
Determine pollutant limits using
site-specific value for
up to six Input parameters.
Pollutant Limits
Management Practice
Monitoring and reporting
Comply with pollutant limits.
No
Do not place sewage sludge In monoflll.
Figure 5-1. Sewage Sludge Monoflll
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SECTION SIX
GENERAL SITING REQUIREMENTS
When siting a monofill, special consideration must be given to evaluating
sites near airports, 100-year floodplains, wetlands, fault areas, seismic
impact zones, and unstable areas. Requirements for siting monofills in each
of these types of locations have been established by the proposed sewage
sludge regulations to prevent adverse impacts to human health and the
environment. The following sections discuss the potential impacts associated
with the six types of locations and present the rationales used to develop
these requirements.
6.1 AIRPORT SITING REQUIREMENTS
An aircraft/bird strike is defined as any contact between a moving
aircraft and a bird or group of birds. In response to the increasing problem
of bird strikes at airports located near municipal solid waste disposal
facilities, the Federal Aviation Administration (FAA) issued Order 5200.5 on
October 16, 1974. The order states that landfills located within 10,000 ft of
any runway used by turbojet aircraft, or within 5,000 ft of any runway used
only by piston-type aircraft, should be closed. It also recommends the
closing of any landfill located such that it places the airport runways or
aircraft flight patterns between bird feeding, nesting, or roosting areas.
6.1.1 Impacts of Siting Facilities near Airports
The major problem in siting monofills near airports is the high incidence
of bird collisions with airplanes. This hazard is caused by the large numbers
of seagulls and other flocking birds that frequent landfill areas. The
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results of collisions between birds and aircraft range in severity from dents
or holes in the aircraft structure to aircraft accidents and loss of life.
Birds can cause aircraft accidents by penetrating windshields and disabling
crew members or by striking and deforming the turbine engines or other
aircraft parts (Solman, 1973). Bird strikes on windshields may crack,
shatter, or completely destroy a panel, exposing pilots to flying pieces of
glass, bird debris, and high wind velocity. In addition, bird strikes to
windshields may startle pilots, impair their judgment, or distract their
attention (Blokpoel, 1976).
The majority of bird strikes occur on the forward facing parts of the
aircraft. Wide-bodied aircraft have a higher risk of colliding with birds
because they have large frontal areas and large air intakes (Blokpoel, 1976).
Table 6-1 presents statistics for military aviation in the United States in
1973, indicating the distribution of bird strikes by aircraft part struck
(Blokpoel, 1976).
Because of high aircraft velocities, a bird strike can create an enormous
impact. A 4-pound bird (such as a mallard duck) hit by an aircraft at 300
miles per hour (mph) causes an impact with a force of 15 tons over a saucer-
sized area.
For a collision at 600 mph, the force of this impact would be nearly 60
tons (Solman, 1973). Statistics for civil aviation in the United Kingdom and
the Soviet Union indicate that over two-thirds of all bird strikes occur at
speeds of 92-184 mph (Blokpoel, 1976).
Bird strikes pose a greater hazard to jet aircraft than to propeller
aircraft (Department of Interior, 1978). The rotating blades of a propeller
aircraft tend to protect the piston engine, whereas turbine engines are
usually exposed to direct bird ingestion, which can deform or destroy the
rotor and stator blades of the engine's compressor (Blokpoel, 1976).
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TABLE 6-1. Distribution of Bird Strikes by Aircraft Part Struck for U.S. Military
Aviation (1973)
Aircraft Part
Percentage of Bird Strikes (%)
Wing
Tail
Nose
Windshield
Engine
Landing Gear
Other
27.8
1.6
1.9
5.5
32.8
2.7
17.7
Source: Blokpoel, 1976.
6-3
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Observations of daily, seasonal, and operational patterns of bird strikes
at airports have revealed that an estimated 75% of bird/aircraft collisions
occur during takeoff and landing (Blokpoel, 1976). These collisions pose a
serious hazard to aircraft because any sudden loss of power or control during
this time can be particularly dangerous (Ultrasystems, Inc., 1977). Studies
have determined that over 62% of bird strikes occur below altitudes of 500 ft
(FAA, 1974) . Air Force statistics for 1972 indicate that 86% of bird strikes
occurred below 2,000 ft, and 93% occurred below 3,000 ft (Blokpoel, 1976).
Impact altitude statistics compiled by the FAA (FAA, 1978) agree with these
percentages.
6.1.2 Regulatory Requirement for Siting Monofills near Airports
Because each airport presents a unique topographical and ecological
environment, uniform national standards for monofills located near airports
are not appropriate. Each airport environment must be considered individually
to assess the bird-strike hazard for that area. For this reason, EPA has
established a broad, performance-based requirement for minimizing bird strike
hazards posed by monofills. As for standards regulating solid waste disposal
facilities (40 CFR Part 257) and those regulating municipal solid waste
landfills (40 CFR Part 258), the requirements for sewage sludge monofills
adopt the minimum distances from airport runways specified in FAA Order
5200.5. Sixty-two percent of all bird strikes occur below altitudes of 500
ft, and aircraft are generally below this altitude within the distances
specified in the FAA Order (44 FR 53459, September 13, 1979). EPA therefore
believes this restriction will prevent most bird/aircraft collisions caused by
the proximity of monofills to airports, without placing an undue burden on the
regulated community.
The distance from the runway to the boundary of the monofill is measured
radially from the end of the runway to the boundary. The distance can be
determined using recent United States Geological Survey (USGS) 7-1/2-minute
6-4
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maps, scale aerial photographs of the area, or plot plans of the facility and
the surrounding area (EPA, 1980).
6.2 FLOODPLAIN SITING REQUIREMENTS
Large regions of the United States are susceptible to flooding (see
Figure 6-1) (GCA, 1986a). Monofills sited in these regions can pose threats
to human health and the environment in a variety of ways. Flooding can cause
erosion of landfill cover material, allowing increased infiltration of water
through the final cover or through any joints between covers and liners.
Increased water content in the monofill can lead to increased leachate
production, with increased potential for surface and groundwater
contamination. The large water volumes and high flow velocity associated with
floods can cause washout of wastes, also leading to surface-water and
groundwater contamination. Wave action and flowing water can destroy
containment structures and levees, and underseepage can weaken them. Weakened
containment structures can increase the vulnerability of monofills during
future flooding activity. Finally, flooding can relocate stream channels near
the monofill, causing or worsening runon to the working face of the facility
(MITRE, 1980; MRI, 1984).
6.2.1 Types of Floods Occurring in 100-yr Floodplains
The magnitude of a flood is usually described by its statistical frequency
of occurrence. According to MRI (1984), "The differences between 10-, 100-,
and 500-year floodplains are most commonly differences in elevation and size
of area inundated." Floods occurring in floodplains can be divided into two
categories: floods due to increased water elevation and coastal floods
(MITRE, 1980).
6-5
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a\
o\
areas that have serious agricultural,
urban, and other flooding
FIGURE 6-1. Existing Flooding Problems in the United States (Water Resources Council, 1978)
-------
The types of flooding due to increased water elevation or flow velocity
include riverine floods, shallow floods, sheet runoff, ponding, lacustrine
floods, and alluvial fan flooding. These types are described below (MITRE,
1980):
Riverine floods -- A riverine flood is the overflow of channelized
water onto the surrounding floodplain. The velocity of a riverine
flood can reach 30 ft/sec, which is enough to wash out the contents of
a landfill.
Shallow floods -- A shallow flood is an unconfined flood occurring in a
topographically low area. Shallow floods include sheet runoff, which is
"the broad unconfined downslope movement of water across gently sloping
terrain" and ponding, which is "the accumulation of runoff or flow in a
depression that has no natural or manmade subterranean or rim outlets,
culverts, or pumping stations."
Lacustrine floods -- A lacustrine flood results from the increase in
elevation of a lake due to seasonal and long-term water fluctuations.
Alluvial fan flooding -- Although flooding in an alluvial fan often
follows the existing stream channels, unpredictable channel flow is
common. Landfill containment structures can be threatened when the
direction of channelized flow, predicted to be parallel to dikes and
levees, becomes perpendicular. A flood with a velocity of 4 to 6
ft/sec can be sufficient to disintegrate an earthen levee.
Coastal flooding is defined as flooding accompanied by wave action.
Facilities 500 ft inland can sustain severe damage during a 100-yr storm, and
even facilities 1,000-2,000 ft inland have been known to sustain damage,
particularly if they were not elevated above the height of the incoming waves
(MITRE, 1980). Monofills in such locations would be subject to daily tides,
wave setup, tsunamis (tidal waves), storm surges, and wind surges.
6.2.2 The History of the 100-yr Floodplain as an EPA Regulatory Standard
Executive Order (EO) 11988, signed into effect on May 24, 1977, requires
that each Federal agency "shall provide leadership and shall take action to
reduce the risk of flood loss, to minimize the impacts of floods on human
safety, health and welfare, and to restore and preserve the natural and
6-7
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beneficial values served by floodplains in carrying out its responsibilities"
(EO 11988, 1977). EPA addressed this order in the Criteria for Classification
of Solid Waste Disposal Facilities (44 FR 53438, September 13, 1979) by
requiring that "facilities or practices in 100-yr floodplains shall not
restrict the flow of the base flood, reduce the temporary water storage
capacity of the floodplain, or result in wash out of solid waste, so as to
pose a hazard to human life, wildlife, or land or water resources" (40 CFR
Part 257.3-1). EPA has used an almost identical requirement in its rule for
municipal solid waste landfills and for sewage sludge monofills.
EPA considered many factors in its choice of the 100-yr floodplain as its
regulatory standard. When EPA promulgated regulations for hazardous waste
management facilities located in floodplains (40 CFR Part 264.18b). EPA
considered using the 500-yr floodplain designation rather than the 100-yr
designation. The U.S. Water Resources Council (WRC) recommends restricting
"critical actions," defined as "any activity for which even a slight chance of
flooding would be too great" in the 500-yr floodplain (43 FR 6030, February
10, 1978). Initially, EPA decided that hazardous waste management facilities
were "critical activities" and proposed restricting their activity in the 500-
yr floodplain. Because of almost unanimous opposition to the proposed
standard (EPA, 1983), however, EPA adopted the 100-yr floodplain restriction
in its final rule (46 FR 2847, January 12, 1981). This decision took into
account the following (EPA, 1983):
EO 11988 does not authorize regulation of activities in the 500-yr
floodplain.
EPA did not have sufficient information to justify use of the 500-yr
floodplain designation.
Maps of the 500-yr floodplain were available for only very limited
portions of the United States. The development of 500-yr floodplain
maps would place a large financial burden on the regulated community.
Use of the 500-yr floodplain designation would restrict large areas of
the United States, such as the mid-Atlantic region, the Southeast, and
the Gulf States.
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The 100-yr floodplain is the designation established for use by the
U.S. Geological Survey, the U.S. Army Corps of Engineers, the Federal
Insurance Administration, and many other agencies.
The Agency determined, therefore, that the 100-yr floodplain was the
appropriate regulatory standard for both hazardous waste facilities and sewage
sludge monofills. The Agency's selection of the 100-yr floodplain standard
was supported by analyses of present and past environmental impacts associated
with washouts at waste management facilities. An examination of environmental
impacts linked to the flooding of these facilities justified the regulatory
view that the 100-yr floodplain criterion poses minimal environmental impact.
6.23 Impacts of Siting Facilities in Floodplains
The potential for contaminant releases from facilities located in flood-
prone areas is considerable. The cause and severity of release can range from
increased leachate production in inundated landfills to a complete washout of
facilities. The destructive forces associated with floods depend on location,
depth, velocities, flood duration, speed of onset, groundwater level, amount
of debris in the flood waters, and chemical properties of the sewage sludge.
These factors limit the time for implementation of emergency measures aimed at
protecting the facility or removing wastes to a safe location. A discussion
of these factors follows:
Location -- Facilities located in the middle of a 100-yr floodplain are
more likely to be inundated from all sides by the 100-yr flood, whereas
facilities located on the edge of the 100-yr floodplain are more likely
to have only one side exposed to the flood source (MITRE, 1980).
Proximity of other structures -- Close proximity of other structures to
landfills will increase floodwater elevations and can increase flow
velocities downstream. Nearby structures can expose the landfill to
channeling effects, and the landfill can cause or exacerbate a channel
effect on structures downstream from the facility (MITRE, 1980).
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. Flood depth -- Depth of the flood waters determines the strength of the
hydrostatic forces in effect during the flood. Vertical loading can
cause uplift and lateral displacement of wastes and is directly related
to leachate generation. Horizontal loading can cause washout of wastes
(MRI, 1984).
. Floodwater velocity -- Floodwater velocity affects the momentum and
damage potential of the flood waters. As floodwater velocity
increases, erosion of cover material tends to increase, causing damage
to landfill structures. Floodwater velocity also affects the momentum
and damage potential of the debris and sediment carried by the flood
(MRI, 1984).
Duration of flooding -- The duration of a flood affects the degree to
which soils and building materials are saturated, contributing to their
weakness, and increases the magnitude of leachate generation and
leachate seeps (MRI, 1984).
Speed of flood's onset -- Speed of a flood's onset is significant
because it determines the warning time that monofill personnel will
have to initiate emergency procedures to prevent washout of sewage
sludge.
Groundwater level -- Groundwater level at the time of flooding is an
important factor in determining the impact of the flood on the
integrity of landfill structures.
Sediment and debris content of flood -- In addition to causing impact
damage, sediment and debris from a flood can bury waste. Hidden from
view, these wastes can potentially endanger human health and the
environment.
Chemical properties of sewage sludge -- the chemical characteristics of
the sewage sludge in the monofill can affect their rate of dispersion
following washout from the landfill. According to one theory (MRI,
1984), chemical constituents that tend to be widely diluted and
dispersed by the flood waters cause the least adverse impacts on human
health and the environment, whereas chemical constituents that remain
concentrated in a small area will tend to cause greater impacts.
Chemical properties that tend to increase the dispersion and dilution
rates of constituents are water solubility, hydrolytic behavior and
rate of volatilization, adsorption to suspended particulates and
sediment, and biodegradation (MRI, 1984).
Because flooding is a surface-water phenomenon, surface waters are the
major recipients of contaminants. When contaminants enter surface waters,
they migrate rapidly to downstream waterways. The rapid transport processes
produce large areas of surface water contamination. In coastal or estuarine
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areas, tidal effects can disperse contaminants both upstream and downstream of
the source. Although mixing and dispersion generally dilute contaminant
concentrations far from the source, contaminant adsorption on sediments can
produce a long-term problem. Contaminated sediments will be both dispersed
over the inundated land surfaces and transported downstream as part of the
river sediment load after the flood subsides, resulting in widespread
contamination.
Many contaminants that tend to adsorb on sediments (i.e., many organics
and heavy metals) will remain long after soluble and suspended contaminants
have been swept downstream. Suspended contaminants will tend to settle in
slow-moving portions of the river or downstream reservoirs. In coastal areas,
they may spread up and down the coast as well as offshore, producing long-term
contamination problems that can adversely affect downstream water supplies and
aquatic resources many years after the source of contamination has been
cleaned up. Contaminants in sediments will continue to leach back into
surrounding surface waters and contaminate surface waters downstream. There,
they may destroy benthic organisms or enter the benthic food chain, resulting
in toxic effects at higher trophic levels, i.e., important fisheries.
Recreational use of the waters may also be impaired.
Contamination of surface waters and sediments due to releases from waste
management facilities can destroy aquatic organisms directly through toxic
effects, including accumulation of low-level releases in the food web, and
indirectly through destruction of habitat. Contaminated sediments may destroy
spawning grounds for fish and kill shellfish and other benthic invertebrates
that inhabit the sediments. Fisheries may be damaged in turn due to the
elimination of the benthic food supply or through the consumption of
contaminated organisms by fish. Destruction of spawning habitat and toxicity
of the waters to sensitive, early life stages may also limit the reproductive
success of fisheries. Other indirect effects include changes in species
composition and diversity when sensitive species are eliminated and replaced
by less desirable pollution-tolerant species. In severe cases, all organisms
near the release may be destroyed.
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The release of wastes to surface waters also may result in both acute and
chronic human-health effects. The primary route of exposure is through the
ingestion of drinking water. The ingestion of fish and other aquatic
organisms that accumulate chemicals is also of concern. Human-health effects
may exist at lower levels of bioaccumulation than those which affect
indigenous aquatic organisms. Recreational use of surface water for water-
contact activities such as swimming can also result in contaminant exposure.
A major concern associated with the effects of surface-water contamination on
human health is that existing ambient water-quality criteria for human toxic
and carcinogenic protection are in many cases below the detection limits in
water. Potentially toxic releases from waste management facilities can
therefore go undetected. Additionally, the human-health effects of chronic
exposures may not be exhibited for decades.
Surface waters represent an economic asset to regional and local areas.
Contaminant releases to surface waters that result in widespread, long-term
degradation of water quality can affect agricultural and industrial use, i.e.,
food processing. Any degradation of water quality will result in a loss to
the community.
6.2.4 Preventive Measures and Emergency Responses to Flooding of Facilities
It is difficult and expensive to design preventive measures that can
withstand the forces of a major flood. The two major approaches are (1) flood
protection measures that rely on diversion structures such as levees, dikes,
and floodwalls to divert the flood waters away from units and prevent
inundation and (2) flood-proofing measures that allow the flood waters to come
in contact with units, but that include design features to prevent damage.
The latter approach includes designing fencing units to prevent impacts from
floating debris, grading landfills to maximize runoff and minimize erosion,
and providing drainage systems to facilitate the collection and removal of
runon and runoff (MITRE, 1980).
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Emergency responses to contaminant releases caused by flooding are
difficult to implement and generally not very effective. In the event of a
washout or major release, wastes usually cannot be recovered. Preventive
measures, such as moving waste to a safe location or erecting flood protection
structures prior to an encroaching flood, are also difficult to implement due
to the difficult working conditions and the general disruption of
transportation systems (such as access roads) and other services that
generally occurs during floods.
When contaminants are released into surface waters, they spread rapidly
over large areas. This rapid spreading may result in long-term sediment
contamination that extends far downstream, as well as soil contamination in
downstream land areas inundated during the flood. These problems may persist
for many years after the facility has been cleaned up. Offsite removal of
contaminated sediments generally is not feasible due to the large extent of
the affected areas.
It is generally impossible to monitor a release during a flood because
rapid transport and dilution typically move the peak concentrations of surface
water contaminants far downstream before they can be measured. Site access is
also a problem during a flood. Even if the site is accessible, a major
sampling effort would be required to characterize the temporal and spatial
variations in pollutant concentrations. These variations are very important
because of the dynamics of the contaminant release and flow conditions.
Because of the difficulty in assembling a sampling team given the short lead
time and hazardous working conditions during floods, the monitoring of
sediments and surface-water concentrations usually must wait until after the
flood has subsided. Monitoring fish-tissue concentrations and biological
impacts such as changes in abundance, species composition, and diversity also
is important, but this task involves a major long-term effort because
important changes often occur gradually
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6.2.5 Case Studies
EPA has examined case studies that depict many of the problems associated
with locating waste management facilities in floodplains (EPA, 1988a). These
studies illustrate (1) the potential for waste releases in floodplains, (2)
the common release pathways, and (3) the potential impacts associated with
these releases. The observed waste releases were caused by flooding of waste
sites, dike failures, streambank erosion, contaminated runoff, or shallow
groundwater contamination recharging a nearby stream. In all cases,
continuous or frequent release to nearby surface waters occurred due to
failures in monofill design and operating specifications. Flooding, however,
had been responsible for rapid dispersion of a large quantity of contaminants,
Environmental impacts observed included surface-water contamination, fish and
aquatic organism kills, and long-term sediment contamination.
6.2.6 Regulatory Requirement for Siting Monofills in Floodplains
EPA's requirement states that a sewage sludge monofill shall not restrict
the flow of a base (100-yr) flood; reduce the temporary water storage capacity
of a floodplain; or present a hazard to human health, wildlife, and land and
water resources because of a washout of sewage sludge. Monofills can employ a
variety of flood controls to meet this requirement, several of which follow
(MITRE, 1980):
Slope -- Location of monofills below grade causes ponding that can
carry wastes out of the monofill in solution or suspension and increase
leachate production. A unit slope greater than 2% but less than 5% will
inhibit the ponding effect, but will not lead to increased erosion.
Drainage capacity -- A leachate collection system can be used during
emergencies to increase the drainage capacity of a landfill. Permanent
drainage channels or ditches should be constructed on the uphill side
of the monofill to divert water around the site. Portable drainage
structures can be used during flooding; however, the speed of flood
onset must be considered in choosing such structures for flood
protection.
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Fencing -- Any fencing used around a monofill should be permeable.
Permeable fences will allow water to pass through, making them less
likely to be carried away by flood waters and reducing the potential
impact damage caused by debris in the flood waters.
Diversion structures -- Levees are the most commonly used diversion
structure; however, flood walls and ditches can also be used. Levees
are generally constructed of earthen materials and are designed to
provide flood protection from seasonal high water. They are, however,
subject to failure from underseepage as a result of flood inundation.
Flood walls are constructed of construction materials such as concrete
or steel sheet piping and are designed to prevent inundation of
adj acent land.
The first step in determining compliance with the requirement is to
determine whether the monofill is located in a 100-yr floodplain. This
information can be obtained from existing permits and operation applications
or from 100-yr floodplain maps. These maps are available from the following
sources (EPA, 1980) :
State flood control agencies or other departments
Federal Emergency Management Agency (FEMA), Flood Insurance Rate Map
(FIRM), or Flood Hazard Boundary Map (FHBM)
Local and regional planning and zoning agencies
Soil Conservation Service, U.S. Department of Agriculture
U.S. Army Corps of Engineers
National Oceanic and Atmospheric Administration
Federal Housing Administration (HUD)
U.S. Geological Survey
Bureau of Land Management, U.S. Department of the Interior
Bureau of Reclamation, U.S. Department of the Interior
Tennessee Valley Authority
River basin commissions and special flood control districts
Local and State agencies involved with public works construction (i.e. ,
bridges, culverts, highways, channel improvements, and urbanization
studies)
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Additional assistance can be obtained from the State agency charged with flood
protection or floodplain management, any of the map-source agencies with the
necessary expertise previously listed, or a qualified professional firm.
After determining location with respect to 100-yr floodplains, an owner or
operator should determine if the facility is protected from washout by a 100-
yr flood (EPA, 1980).
Types and effectiveness of washout protection used in each area of the
facility below the 100-yr flood level should be considered. Washout
protection may include:
Dikes
Levees
Benns
Flexible linings
Vegetative cover
Riprap
Diversion of high velocity flows around the facility
. Change in soil matrix by chemical alteration
Flood flow velocity should also be considered (EPA, 1980) . A flood flow
velocity of at least 2.5 times the average velocity over the entire floodplain
cross section should be used for those portions of the facility in the
floodway. A minimum value of 1 times the average velocity over the entire
floodplain cross section should be used for those portions of the facility in
the floodway fringe. That is,
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v = Q/A
where v = average velocity
Q - 100-year flood flow (cfs)
A = cross-sectional area of floodplain
Matrices comparing the efficiency of each type of washout protection with
different flood-flow velocities are available in the U.S. Department of
Transportation's Hydraulic Engineering Circular No. 15 and the U.S. Army Corps
of Engineer's Shore Protection Manual (EPA, 1980). These matrices can be used
to help evaluate the adequacy of protection for each facility
63 WETLANDS SITING REQUIREMENTS
The wetlands of the United States, composed in part of inland and coastal
swamps, bogs, marshes, sloughs, mudflats, wet meadows, natural ponds, and
river overflows, serve as important natural hydrologic, ecologic, social, and
economic resources. Scientific studies have come to recognize wetland
habitats as essential breeding, rearing, and feeding grounds for numerous
species of fish and wildlife, including many endangered species. These
ecologically sensitive habitats have been found to play important roles in
both flood protection and pollution control. The general public, government,
and business, however, have had little concern for wetlands protection, thus
these areas have been inconsistently regulated by Federal, State, and local
governments. Such policies resulted in the direct destruction of an estimated
48 million acres of wetlands through draining, dredging, and landfilling for
agricultural, residential, and commercial development (43 FR 4942, February 6,
1978). A recent study by the Office of Technology Assessment (OTA, 1984)
concluded that, based, on current policies and trends, an estimated 300,000
acres of wetland resources are lost each year. Increasing scientific
understanding of the functions and values of wetlands indicates that this
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conversion will cause serious economic consequences throughout the country
(Baldwin, 1985).
Despite recent concern by the public and State and Federal regulating
authorities, wetland protection programs are neither comprehensive nor
consistent (OTA, 1984). The Clean Water Act (CWA) (Pub. L. 92-500 as amended
by Pub. L. 92-217 and Pub. L. 95-576; 33 U.S.C. 1251 et seq.) stands alone in
addressing adverse effects to wetlands by regulating impacts to "waters of the
United States." An expansive definition of the latter has been viewed to
encompass wetlands indirectly. The ambiguousness of the statutory language,
however, has lead to disputes over which Federal agency or agencies have
primary authority to implement a Federal regulatory program to protect
wetlands from waste disposal. The result has been an inconsistent and often
incomprehensive wetland protection system, ultimately mandating a reevaluation
of present policy and issuance of a natural wetlands protection standard
administered solely through and by the EPA.
The term "wetlands" refers to those areas inundated or saturated by
surface or ground water at a frequency and over a duration sufficient to
support a prevalence of vegetation typically adapted for life in saturated
soil conditions. Wetlands include, but are not limited to, swamps, marshes,
and bogs. The justification for protecting wetlands focuses on the important
ecological functions and resource values that wetlands provide, including the
following (OTA, 1984):
Wetlands store runoff and slow the downstream flow of water, thus
reducing floodpeaks and frequency of flooding in downstream areas.
By temporarily or permanently retaining pollutants, wetlands can
improve, to varying degrees, the quality of the water that flows over
and through them.
Wetlands provide food and habitat for many game and nongame animals.
Approximately 20% of all plant and animal species listed by the Federal
government as threatened or endangered depend heavily on wetlands.
Wetlands may significantly reduce shoreline erosion caused by large
waves and major coastal and riverine flooding.
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Some wetlands are recharge areas to groundwater systems that supplement
local or regional groundwater supplies through infiltration/percolation
of surface water.
63.1 Impacts of Siting Facilities in Wetlands
Wetland environments may be adversely affected in several ways by the
proximity of solid waste land disposal facilities. Depositing wastes into
wetlands causes physical disturbances and creates potential for the accidental
discharges of wastes into the ecosystems (GCA, 1986b). These physical and/or
accidental impacts can directly affect the chemical, biological, and human-use
characteristics of the aquatic ecosystems. The rule 40 CFR 230.42(a)(3)(b)
states:
The loss of wetlands.... is likely to damage or destroy habitat and
adversely affect the biological productivity of wetland ecosystems by
smothering, by dewatering, by permanently flooding, or by altering
substrate elevation or periodicity of water movement. The addition of
materials may destroy wetland vegetation or result in advancement of
succession to dry land species. It may reduce or eliminate nutrient
exchange by a reduction of the systems productivity, or by altering
current patterns and velocities. Disruption or elimination of the
wetlands system can degrade quality by obstructing circulation patterns
that flush large expanses of wetland systems, by interfering with the
filtration function of wetlands, or by changing the aquifer recharge
capability of a wetland. Accidental discharges can change the wetland
habitat value for fish and wildlife. When disruptions in flow and
circulation patterns occur, apparently minor loss of wetland acreage may
result in major losses through secondary impacts.
The degradation of wetlands by foreign substance intrusion can cause the
destruction of recreational and commercial fisheries. Placing waste materials
in wetlands can affect the suitability of recreational and commercial fishing
grounds as habitat for consumable aquatic and terrestrial organisms by
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destroying migration and spawning areas, as well as food sources (40 CFR Part
230.51b). These natural aquatic areas also provide aesthetic, recreational,
scientific, and educational values to the public.
In addition, wetlands are commonly near to or contain surface waters and
by definition have saturated soils and a shallow water table. Therefore, the
release of wastes often affects surface waters and ground waters surrounding
the wetlands. Surface water transport results in extensive surface water and
sediment contamination. The difficulties in performing corrective actions for
widespread contamination and the extensive wetland disruption involved in
sediment removal have been documented in case studies (EPA, 1988a).
63.2 Current Federal Protection Measures
President Carter advanced Federal protection of wetlands in 1977 by
signing EO 11990 for protection of wetlands and EO 11988 for floodplain
management (EO 11988 is discussed in Section 6.2). These Federal directives
prescribe measures to be taken by Federal agencies to avoid adverse impacts on
wetland and floodplain resources (GCA, 1986b) .
EO 11990 articulates a strong Federal policy favoring the protection of
wetlands. It directs Federal agencies, in carrying out their
responsibilities, to minimize the destruction or degradation of wetlands and
to preserve and enhance their natural and beneficial values. It also requires
Federal agencies to avoid undertaking or providing assistance for new
construction, including draining, dredging, and filling, in wetland areas
unless there is no practical alternative and only if measures are taken to
minimize harm to wetlands. In principal, EO 11990 appears to control Federal
activities involving waste disposal in wetlands. In practice, however,
because Federal directives like this one are largely enforced by the Federal
agencies themselves, it is difficult to measure the extent to which Federal
waste disposal in wetlands has been affected. In addition, this Executive
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Order does not apply to private, non-Federal waste disposal activities in
wetlands (GCA, 1986b).
The ineffectiveness of the present Federal system is demonstrated by EPA's
use of its veto authority under §404(c) of the CWA. Although the U.S. Army
Corps of Engineers releases about 11,000 permit requests each year, permit
denials are estimated to be less than 3%, with only a few §404(c) veto actions
being taken by EPA. Only about a dozen permit controversies with the Corps
have been evaluated by regional offices for resolution to the Washington
headquarters under §404(c) procedures. The rare use of §404(c) reflects the
unusual role created by Congress for EPA as overseer of another agency's
regulatory program (Baldwin, 1985).
Estimates of current national wetlands loss also exemplify the problems
with Federal implementation. Approximately 99 million acres of wetlands are
located in the 48 contiguous States, comprising 5% of the total area (EPA,
1987b). Of these 99 million acres, between 300,000 and 500,000 acres of
wetland resources are adversely affected annually. Fifty-thousand acres of
this wetlands loss are permitted under §404. An unknown amount of loss,
occurring through discharges that could come under §404 jurisdiction but that
are currently unregulated or illegal, is probably equal to at least the amount
of permitted loss (EPA, 1986). EPA believes these unnecessary losses can be
prevented through a comprehensive and consolidated Federal system that does
not depend on the interactions of different agencies with different Federal
(EPA) administrative and substantive duties. Such a policy would have as its
ultimate goal the development of national criteria and standards.
63 J Regulatory Requirement for Siting Monofills in Wetlands
The sewage sludge monofill criteria include provisions that impose a ban
on locating monofills in wetlands. EPA believes this ban is necessary because
monofills cause irreparable harm to these sensitive ecosystems. This decision
is consistent with Agency policy for the protection of the Nation's wetland
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resources. This policy of wetlands protection has been articulated over the
years in various Agency directives on wetlands, beginning with the policy
statement issued by the first EPA Administrator in 1973. It also is embodied
in regulatory form in the guidelines for specification of Disposal Sites for
Dredged or Fill Material (40 CFR Part 230) effective under §404(b)(l) of the
CWA.
Recently, the Agency has identified wetlands protection as a top priority,
aggressively implementing the §404 program, increasing enforcement against
illegal discharges, and specifying other measures as necessary. To this end,
the Agency considers the wetland requirement an essential measure for
protecting wetlands resources.
For consistency with the CWA, the revised criteria adopts the definition
of wetlands used in the §404(b)(l) guidelines. These guidelines, first
promulgated in 1975 and then amended in 1980, specify the analytical tools to
be used in evaluating and testing the impact of dredged or fill material
discharges on waters of the United States, including wetlands. Fundamental to
the guidelines is the precept that discharges into aquatic ecosystems should
not be allowed unless it can be demonstrated that such discharges will not
have an unacceptable effect. In particular, the guidelines identify filling
operations in wetlands as among the most severe environmental impacts. For
this reason, the guidelines are directly relevant to solid waste disposal in
wetlands and provide the basis for decision making with respect to such
activities.
6.4 FAULT AREA SITING REQUIREMENTS
Earthquakes are part of the Earth's natural dynamics. When they occur,
they are usually catastrophic, causing the loss of life and property. North
Americans typically associate the west coast of the continent with areas of
known seismic activity, but serious earthquake shocks have also occurred in
and near the east coast (Legget and Karrow, 1983) .
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Earthquakes are usually caused by movements along faults, which are
fractures in rock along which the adjacent rock surfaces are differentially
displaced. Faults may vary in length from a few meters to many kilometers.
The presence of faults indicates that at some time in the past movement has
occurred by either a slow slip (movement along the fault plane) that produces
no ground motion, or a sudden rupture, which results in the perceptible ground
motion known as an earthquake (Bolt, 1978).
Faults assume different geometric forms: normal, reverse and strike-slip.
A normal fault has movement down the dip of the rock, while a reverse or
thrust fault has movement up the dip of the rock. Since vertical
displacements seen at the surface are produced by both normal and reverse
faults, both of these faults are referred to as dip-slip faults. A strike-
slip fault has a relative displacement at a right angle to the dip, as viewed
from the ground surface. This type of fault is sometimes referred to as a
wrench or tear fault (Legget and Karrow, 1983) Strike-slip or dip-slip
faults can cause the partial or total collapse of buildings, bridges, and
tunnels; failure of manmade and natural slopes; and damage to water or other
types of distribution systems.
When displacement along a fault occurs, movements of great masses of
material naturally develop dynamic effects of magnitude that initiate
vibrations or seismic waves within the earth's crust. The seismic waves
travel for great distances in all directions, thereby creating effects over a
wide area (Legget and Karrow, 1983). Section 6.5 discusses seismic zones in
more detail.
The fracturing that faults represent is a normal part of the dynamic
process of geologic development. Therefore, some faults are of great age,
whereas others seen in Pleistocene deposits are, correspondingly, very young
geologically. The age of a fault is often related to whether or not it is
active; young faults tend to be more active. Only in active faults is
movement on the fault line expected to take place in the foreseeable future.
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The faintest possibility of movement on a fault plane under any engineering
structures, however, should be avoided, even to the extent of abandoning a
proposed building site (Legget and Karrow, 1983).
Damage can also be caused by the displacement of the fault itself. This
particular earthquake hazard is very limited in area and can usually be
avoided by obtaining geologic advice on the location of active faults before
undertaking construction (Bolt, 1978).
6.4.1 Impacts of Siting Facilities in Fault Areas
Constructing a monofill over an active fault can have serious
consequences. Facilities located directly over a fault may be damaged, for
example, by lining rupture, during the fault displacement. Lining rupture may
result in an uncontrolled release of contaminants into the environment.
Investigating sites for surface-fault rupture is a deceptively difficult
geologic task. Many active faults are complex, consisting of multiple breaks,
yet the evidence for identifying active fault traces is generally subtle or
obscure. The distinction between active and long-inactive faults may be
difficult to make. To assist with this task, the California Division of Mines
and Geology has developed guidelines for detecting and evaluating the hazard
of surface and near-surface fault rupture (California, 1975).
The general fault zone can be divided into a main fault zone, a branch
fault zone, and a secondary fault zone. The main fault zone contains the main
fault, i.e., the fault with the greatest displacement or length, and closely
associated faults. The width of this zone ranges up to 3,000 ft, but in most
cases is half that width or less. Faults that diverge from and extend well
beyond the main zone of faults are referred to as branch faults. Secondary
faults are completely separate from the main fault, sometimes several hundred
feet to a few miles away. Often associated with main, branch, and secondary
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faults are small, subsurface faults that are evident as fault planes running
parallel to the fault and typically are considered a part of that fault.
Adjacent to the fault rupture a zone of deformation is commonly found.
This is an area where the ground has been bent or warped as a consequence of
the two surface planes moving against one another. Surface deformation may
occur within a zone several tens to several hundred feet wide. Structures
located within this zone are subject to distortion and are likely to be
damaged.
6.4.2 Regulatory Requirement for Siting Monofills in Fault Areas
The Agency believes that monofills may be affected by fault rupture and
surface deformation resulting from earthquakes. To minimize the risk, the
rule states that new sewage sludge units shall be located 60 m (200 ft) or
more from a fault displacement from Holocene time. (The Holocene is a
geologic time period, known as an epoch, that extends from the end of the
Pleistocene to the present and includes approximately the last 11,000 yr) .
The proposed regulation should prevent siting on the zone of deformation where
the ground may be bent or warped.
The Agency's proposal reduces the possibility that landfill slopes would
be impaired by fault rupture, and the resulting potential for exposing waste
to surface runoff.
6.5 SEISMIC IMPACT ZONE
Another aspect of the effect of earthquakes on monofill siting is the
extent of the seismic impact zone. Geologic features can contribute
significantly to the local effects of earthquake shock. Because seismic waves
travel at different speeds in different materials, the effects of seismic
waves in rock and unconsolidated material will vary (Legget and Karrow, 1983).
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Larger areas are influenced in the eastern United States than in the western
United States (USGS, 1981).
Regional seismicity maps have been available since the 1950s to aid the
engineer in reducing earthquake effects on buildings and other structures.
Regional seismicity or risk maps usually do not attempt to reflect geologic
conditions or take into account variations due to soil properties. The maps
primarily provide insight into the relative hazard of seismicity across the
United States together with the relative importance of various parameters
involved (Algermission and Perkins, 1976; and Bolt, 1975).
The U.S. Geologic Survey published an open-file report addressing the
probabilistic estimate of maximum acceleration in rock in the contiguous
United States. The report presents maps of the relative earthquake hazard in
various "seismic zones" based on a constant-probability level. Maps provided
with the report identify the maximum horizontal accelerations in hard rock
expressed as a percentage of the Earth's gravitational pull, g, with a. 90%
probability that they will not be exceeded in 10, 50, and 250 years
(Algermission and Perkins, 1982).
A single parameter, such as an estimate of maximum acceleration, does not
provide all of the information necessary to describe the characteristics of
strong ground motion important in structural design. Nevertheless, a wide
range of structures can and have been designed to be earthquake resistant
using peak acceleration as the basic ground motion data (Algermission and
Perkins, 1976).
6.5.1 Impacts of Siting Facilities in Seismic Impact Areas
Earthquakes can affect a waste management facility through ground motion,
surface faulting, earthquake-induced ground failures, and tsunamis. Although
earthquakes cause much less economic loss annually in the United States than
do ground failures and floods, major earthquakes have the potential to cause
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sudden and great loss. Ground motion associated with earthquakes can damage a
monofill by causing dikes and berms to fail, resulting in the exposure of
waste and/or rupture of any leachate collection and liner systems. Runoff
contaminated by contact with exposed waste potentially could contaminate
surface water bodies.
Failure of natural and manmade slopes adjacent to the monofill may also
affect the facility. Failure of these slopes may damage runon and runoff
control systems, leachate disposal/management systems, and the stability of
the containment structure berms. These earthquake effects constitute one
important set of considerations in siting, designing, and constructing these
critical structures (EPA, 1988a)
Earthquakes that occur near waste management facilities pose a risk to the
public and the environment because the motion of the ground during destructive
earthquakes has the potential to damage inplant collection and waste-
processing facilities, i.e., landfills with protective engineering design and
long-term surveillance. The most typical seismic-related damage categories
are:
Failure of structures, tanks, etc., due to a high level of ground
motion
Failure of structures, tanks, impoundments, and landfill containments
due to soil liquefaction and liquefaction-induced landsliding and/or
lurching, or, generally, extensive soil settlement, failure of
structures and tanks due to fault rupture passing through structures,
tanks, and landfills
General landsliding
Failure of impoundments (dams, embankments, etc.)
One major cause of destruction during an earthquake is the failure of the
ground structure by loss of strength. This type of failure typically occurs
in loose, saturated, cohesionless soils. This phenomenon, termed
liquefaction, is a result of an increase in the soil pore water pressure, that
decreases, and sometimes eliminates, the shear strength of the soil.
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Bodies of loose, relatively fine-grained uniform sand below the water
table are susceptible to liquefaction during an earthquake, especially if the
duration of the quake is long enough for the occurrence of a large number of
oscillations involving repeated reversals of shearing strains of large
amplitude. Soil that has lost all strength behaves like a viscous fluid and
often appears in the form of "sand fountains or boils" during earthquakes.
When a soil fails in this manner, a structure resting on it simply sinks
(Prakash, 1981; Terzahgi and Peck, 1967).
Liquefaction causes three types of ground failure: lateral spreads, flow
failures, and loss of bearing strength. Lateral spreads involve the-lateral
movement of large blocks of soil as a result of liquefaction in a subsurface
layer. Flow failures consist of liquefied soil or blocks of intact material
riding on a layer of soil, and are the most catastrophic type of ground
failure caused by liquefaction. Loss of bearing strength when the soil
supporting a building or structure liquefies causes large deformations within
the soil that allow the structure to settle and tip (USGS, 1981).
6.5.2 Regulatory Requirement for Siting Monofills in Seismic Impact Areas
The Agency believes that monofills may be affected by ground motion
resulting from an earthquake. To minimize the risk, all new monofill units
located within a "seismic zone" defined' as having a 10% probability of maximum
horizontal acceleration in hard rock exceeding 0.10 g in 250 years must design
all containment structures, including liners, leachate collection systems, and
surface water control systems, to resist the maximum horizontal acceleration
for the zone.
This requirement also applies to a seismic zone with a 4% probability of
exceeding the maximum horizontal acceleration in 100 years. The Agency
believes that the areas affected by the seismic zone requirement represent the
areas of the United States with the greatest seismic risk. In addition, the
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Agency believes that these probabilities and ranges of maximum horizontal
accelerations are acceptable, and that the requirement adequately protects
human health and the environment.
EPA has included this restriction as a performance requirement for
monofills to minimize the risk of slope and liner failure due to seismic
activity. By minimizing the risk failure of the landfill slopes, the
requirement also reduces the potential for exposure of sewage sludge to the
atmosphere and the possible contamination of runoff by contacting exposed
sewage sludge.
In addition, the Agency requires that no new monofill units shall be
located in areas where support for the structural components is inadequate.
The Agency considers soils with the potential for liquefaction as areas of
inadequate support. An owner or operator must determine if the proposed
monofill site is susceptible to liquefaction. If it is, and protective
measures cannot be incorporated into the design, then the Agency will consider
the site unstable. Unstable areas are further discussed in Section 6.6 of
this document.
6.53 Methods for Determining Seismic Risk
Numerous seismic design methods are available to the owner or operator to
assess the proposed design of the monofill and appurtenances. The two most
commonly used include the seismic coefficient method and the permanent
displacement method. Both methods have been used to evaluate the design of
embankments under seismic loading conditions.
The seismic coefficient method utilizes a static, horizontal inertial
force applied to a potential sliding mass in an otherwise conventional static
limit analysis. This method, commonly referred to as a conventional static
stability analysis, represents earthquake loading by a statically applied
horizontal force. The seismic force is proportional to the weight of the
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potential sliding mass multiplied by the seismic coefficient, which is some
fraction of the acceleration of gravity (Lambe and Whitman, 1969; Hynes-
Griffin and Franklin, 1984).
The permanent displacement analysis estimates permanent displacement in an
embankment due to seismic loading, as discussed by Newmark in his 1965 Rankin
Lectures. A principle parameter in the analysis is the peak bedrock
acceleration determined by a site-specific risk assessment. Using this
method, the motions of a system consisting of a rigid block sliding on an
inclined plane are analyzed. If the base inclined plane is subjected to some
sequence of acceleration pulses (the peak bedrock acceleration) large enough
to induce sliding of the block, the block will come to rest at some displaced
position down the slope. An embankment response analysis of the containment
structure must then be performed. This dynamic analysis requires shear wave
velocities and damping values, consistent with expected strain levels, for all
materials comprising the structure (Hynes-Griffen and Franklin, 1984).
The Department of the Army Waterways Experiment Station published a
miscellaneous paper outlining the procedures for performing a permanent
displacement analysis. The paper presents figures and tables to assist in the
analysis, as well as to indicate situations where the procedure is not
applicable (Hynes-Griffen and Franklin, 1984).
6.6 SITING REQUIREMENTS FOR UNSTABLE AREAS
EPA has chosen to ban the siting of monofills in areas that are determined
to be geologically unstable. These include landslide-prone regions, areas
with comprehensive or expansive soils or ultra-sensitive (quick) clays, and
subsidence-prone areas, including karst terrains.
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6.6.1 Types of Unstable Areas
6.6.1.1 Landslide Prone Areas
Landslide is a general term covering a wide variety of mass-movement land
forms and processes involving the downslope transport of soil and rock
material under gravitational influence. Landslides are a significant hazard
in virtually every State, and often take place in conjunction with other
hazards such as earthquakes, floods, and volcanoes (USGS, 1981). They occur
when earth materials fail under shear stress, and can be triggered by any
human activity or natural event that increases shear stress or lowers shear
strength. The major causes of landslides are (Winterkorn and Hsai-Yang,
1975):
Construction operations or erosion
a Earthquakes and vibrations
Rains or melting snow
Freezing and thawing
Dry spells
Seepage from manmade sources of water
Construction operations or erosion can cause a landslide if they affect
the support of a slope. Slides are common in excavated cuts for highways and
railways and also in quarries and pits. Similarly, erosion of the toe
(bottom) of a slope can leave the remaining slope face unsupported and subject
to sliding. Heavy buildings located close to the edge of a slope can also
initiate a slide.
Earthquakes and vibrations from blasting or construction-related
operations can cause spontaneous liquefaction of loose sand, silt, or loess
deposits situated below the groundwater table. Under similar circumstances,
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some sensitive clays can undergo a decrease in shear strength. If pore
pressures increase to the point of total overburden pressure, the shear
strength of the soil is drastically reduced, causing the soil to flow downhill
like a heavy liquid.
Extremes of temperature and precipitation can contribute to landslides.
Rains or melting snows can cause increased pore water pressures leading to
reduced shear strengths along potential slip faces. Most landslides occur
after heavy rains or during spring snow melts when large quantities of water
can penetrate cracks and fissures. Freezing or thawing can induce cracking in
rock formations that result in rockslides. In silty soils, the freeze-thaw
cycle can increase pore pressures and, consequently, ground surface movements.
Drying also may result in crack formations that reduce the soil's shear
strength, thereby increasing the chance of slides.
6.6.1.2 Expansive Soils
Certain types of soils and soft rocks will expand when they become wet and
shrink when they dry out. Expansive soils are generally rich in clay
minerals, which swell by adsorbing water that enters and expands the spaces
between the mineral's crystalline structures. Upon drying, the spacing
decreases and the clay shrinks. The amount of expansion that can occur
depends on the type and quantity of clay mineral present, and is a function of
time, weight of material resting on top of the expansive clay (confining
load), initial density, and initial water content (Department of Interior,
1974). Montmorillonite clays are the most prone to swelling with bentonite
clay an extreme case that can increase in volume by a factor of 10 from its
dry to its saturated state.
Expansive soils are widely distributed worldwide. Montmorillonites are
most abundant in geological formations throughout the Rocky Mountains, in the
upper Great Plains, in the southern gulf coast plain, and along the Pacific
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coast. They are also locally abundant throughout the Great Basin region, and
along the Atlantic coast.
The extent of damage causd by expansive soils to houses, commercial
buildings, streets, buried utilities, and other structures was estimated at
$7 billion in 1980. Expansive clay formations that do not exhibit natural
excessive shrink-swell activity can become a problem as a result of
construction activities that reduce confining load or increase water access.
6.6.1.3 Subsidence Areas
Subsidence is defined as the lowering or collapse of the land surface
either locally or over broad regional areas (USGS, 1981). Subsidence can be
the result of either natural phenomena or human activities.
Natural causes of subsidence include disolution of limestone and other
soluble materials, earthquakes, and volcanic activity. Limestone and dolomite
are slightly soluble in water and, especially in hot and wet climates,
excessive moisture can cause voids to form in their mineral formations. If
overlying materials collapse or subside into the solution cavities, a surface
depression called a sinkhole will form. Where limestone or dolomite deposits
are widespread and sinkholes are common, the land surface is referred to as
karst topography or karst terrains after a district in Yugoslavia where the
phenomenon is common (Bolt, 1975).
Sinkholes vary in depth from slight indentations to depressions over 100-
ft deep. Typically, depths range from 10-30 ft with areas ranging from a few
square yards to several acres. There are two major classes of sinkholes:
those forming from the collapse of an underground void, and the more common
type, the doline, that develops slowly by the downward solution of the
underlying rock. Surface water entering the first type of sinkhole tends to
flow rapidly underground through outlets called swallow holes. Runoff
draining into a doline, however, usually percolates slowly underground through
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the soil in the bottom of the sinkhole. If a sinkhole becomes clogged, a
temporary pond or lake will form; if the outlet is unplugged, rapid drainage
may occur. This phenomenon occurred at Lake Jackson, a lake of approximately
25 square kilometers near Tallahassee, Florida, that drained on May 22, 1982.
Karst terrains and caverns in the United States are found primarily in
parts of many southeastern and midwestern States. Sinkholes are found in some
western and northeastern States and in Alabama, where soluble limestone and
other rocks present in nearly half of the State have created thousands of
sinkholes that pose serious problems for highways and construction.
Earthquake-related subsidence has taken place mainly in Alaska,
California, and Hawaii, and to a lesser extent in other States. This type of
subsidence results from the vertical movement of faults and may effect broad
areas. In 1964 in southern Alaska, in conjunction with the Prince William
Sound, Alaska, earthquake, more than 70,000 square miles tilted downward more
than 3 ft and subsequently flooded. Subsidence resulting from intense
earthquake groundshaking involves somewhat smaller areas than that resulting
from regional vertical faulting. Intense groundshaking generated during
earthquakes in 1811-1812 in New Madrid, Missouri, caused subsurface sand and
water to be ejected to the surface. This ejection left voids in the
subsurface, causing local compaction of subsurface materials and settling of
the ground.
Volcanic-related subsidence is a potential problem in parts of Alaska,
California, Hawaii, Oregon, and Washington. Subsidence usually is caused by
local collapses above shallow tunnels formed by lava flows. Collapses over
much broader areas also can occur as magma chambers are emptied by volcanic
eruptions (USGS, 1981).
Human activities that cause subsidence include the withdrawal of water,
oil, or gas from the pore spaces in subsurface formations. When these fluids
are removed by pumping, the effective stress on the formation increases as the
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pore pressure decreases. This stress can cause the formation to compress
vertically, resulting in land-surface subsidence.
The most dramatic examples of subsidence caused by withdrawal of oil, gas,
and water are along the Gulf Coast of Texas, in Arizona, and in California.
The harbor at Long Beach, California, has subsided as much as 27 ft from
withdrawal of gas and oil. The Houston-Galveston area of Texas has
experienced as much as 7.5 ft of subsidence locally and an area of about 2,500
square miles has subsided 1 ft or more. Subsidence in the Houston-Galveston
area appears to have been caused mainly by the withdrawal of large amounts of
ground water, although some areas of local subsidence have been caused by the
extraction of gas and oil. Coastal towns in Texas, such as Baytown and
Seabrook, have subsided about 3 ft and are now susceptible to flooding from
storm surges and hurricanes (USGS, 1981).
Recent research suggests that subsidence caused by withdrawing ground
water can cause fissuring (the formation of open cracks) or renewal of surface
movement in some areas cut by pre-existing faults. Surface faulting and
fissuring associated with withdrawal of ground water are believed to have
taken place or to be potential problems in the vicinity of Las Vegas, Nevada,
as well as in parts of Arizona, California, Texas, and New Mexico (USGS,
1981) .
The removal of solid materials from underground deposits can also result
in subsidence. Subsidence has occurred in shallow coal mines where a lack of
adequate roof support caused collapses either during mining or long after
mining had ceased. Subsidence in areas of underground mining has caused
hazardous conditions in parts of Pennsylvania and other Appalachian States,
Colorado, North Dakota, Wyoming, New Mexico, Washington, Iowa, and Illinois.
Subsidence-related damage to surface structures is common in the area around
Pittsburgh, Pennsylvania, where coal has been mined extensively. Subsidence
depressions and pits forming above abandoned underground mines are a hazard in
the Sheridan, Wyoming, area.
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Solution mining also can cause subsidence. When water-soluble minerals
such as salt, gypsum, and potash are dissolved and pumped to the surface so
that the water can be evaporated, huge underground cavities are formed.
Examples of subsidence that are not well known, include the sudden collapse in
1976 of a Grand Saline, Texas street into an abandoned salt mine cavity
created between 1924 and 1949; subsidence in 1974 near Hutchinson, Kansas; and
subsidence in 1971 near Detroit, Michigan (USGS, 1981).
The addition of water to some soils and soft rock formations can cause
subsidence. One type of formation where this can happen is called loess.
Loess has the characteristics of soft rock, being formed from fine-grained
material cemented together in an extremely loose, open structure by a water-
soluble mineral cement. In the dry state, loess is firm and hard and serves
well as a foundation material. When subjected to excessive wetting from
sprinkling or ponding on the surface, however, the mineral cement dissolves
and the soil structure collapses in the saturated area.
Hydrocompaction, or the settling of sediments after water is added, is
another significant cause of subsidence, especially in the arid to semiarid
western and midwestern States. The areas of known compaction include the San
Joaquin Valley, California; Heart Mountain-Chapman Beach and Riverton, Wyoming
areas; Hysham, Montana; Columbia Basin, Washington; Denver, Colorado;
Washington-Hurricane area in southwest Utah and central Utah; and the Missouri
River Basin. Hydrocompaction takes place when dry surface or subsurface
deposits are wet extensively for the first time since their deposition as, for
example, when arid land is irrigated for crop production or an irrigation
canal is built on loose uncompacted sediments. Wetting causes a reduction in
the cohesion between sediment grains, allowing the grains to fill in the
naturally occurring intergranular openings. Hydrocompaction usually results
in a lowering of the land surface from 3-6 ft, although subsidence of as much
as 15 ft has been recorded. The effects of hydrocompaction are usually
uneven, causing depressions, cracks, and wavy surfaces that can seriously
damage canals, highways, pipelines, buildings, and other structures (USGS,
1981).
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6.6.2 Impacts of Siting Facilities in Unstable Areas
In landslide-prone areas, construction of monofills on natural slopes can
cause problems if the shear strength of underlying materials is exceeded by
the placement of waste overburden. Vibrations generated by construction
equipment and heavy vehicular traffic on the site could also trigger ground
movement. During liner construction, care must be taken not to remove the toe
of adjacent slopes that could slide into the monofill.
In areas with expansive clay, liners can be torn or rocked and sidewalls
can collapse if uneven expansion occurs below the monofill. To avoid this
situation, expansive soils can be treated in situ, removed from the site, or
sealed to prevent changes in their moisture content. If expansive clay soils
are deep enough, sufficient overburden can be left in place to prevent
excessive swelling. Regardless of the solution, problems must be recognized
early in the planning stage in order to include proper expansive soil control
measures in the facility design.
In areas that are plagued with subsidence problems due to underground
cavities, there is always a possibility of subsidence occurring below a
monofill. This is a particular hazard if the weight of the placed waste
exceeds the bearing strength of the materials supporting the facility.
The Agency examined case studies and documented events that cited the
types of environmental problems resulting from locating waste management units
in unstable areas. Differential or total foundation movement, loss of
facility structural integrity, sudden and/or emergency release of
contaminants, difficult and costly corrective actions, and contaminant
releases attributed to maintenance or inadequate facility design are all
hazards of locating monofills in unstable areas. The Agency believes that it
is essential for the owner or operator to evaluate extensively the adequacy of
subsurface foundation support before constructing a monofill.
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6.63 Alternatives
The Agency considered three alternative approaches for regulating the
siting of monofills in unstable areas:
1) Provide no standard relating to the siting of monofills in unstable
areas.
2) Develop detailed maps of all unstable areas and prohibit siting of
monofills in those areas.
3) Require demonstrations by all owners/operators that a site is not
subject to damage from unstable conditions.
The first alternative was the simplest and least costly to implement;
however, it was the least protective of the environment and human health.
The second alternative, to map all unstable areas and ban monofills from
these areas, was clearly unworkable. Many unstable areas cover large
geographic regions and to ban monofills within these areas would impose a
great economic burden on communities located in those areas. Additionally the
task of mapping all unstable areas with sufficient detail and accuracy
probably is beyond the capabilities of modern geoscience, as well as too
costly to receive serious consideration.
The third alternative provides the best approach to controlling the siting
of monofills. Owners/operators would be required to perform geotechnical
studies of all proposed sites in order to demonstrate that unstable conditions
do not exist. This method allows the placement of facilities within broad
geographic areas where unstable conditions may potentially exist while at the
same time prohibits the placement of a facility on a specific site where
unstable conditions actually do exist.
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6.6.4 Regulatory Requirement for Siting Monofills in Unstable Areas
The proposed standard requires that sewage sludge units be located in
areas where adequate support for the structural components of the units exist.
Although unstable support conditions may be common over large areas of the
country, there may be places within these regions where monofills can be
safely sited.
For the most part, identification of monofill sites in unstable areas must
be on a case-by-case basis because these areas have not been delineated on a
national scale. National maps are available describing karst terrains and
landslide-susceptible areas, but weak and unstable soils and subsidence-prone
areas appear to be mapped only individually or at the local level.
Under the proposed requirement, the facility owner or operator must
determine if an area is subject to events that may cause or contribute to the
facility's failure. If the unit is located in an unstable area, the owner or
operator must demonstrate to the State that the proposed site is not subject
to destabilizing events.
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SECTION SEVEN
MANAGEMENT PRACTICES
Six areas of management practice requirements are specified by the
proposed sewage sludge regulations. One of these six, pathogen reduction, is
covered under separate title (EPA, 1989). The remaining five -- landfill
cover requirements, disease vector controls, explosive gases controls, access
controls, and runon/runoff controls - - are discussed in this section of the
technical support document for monofills. These management practices are
required under Subtitle D or C of the Resource Conservation and Recovery Act
(RCRA) and have been incorporated to some extent into the proposed sewage
sludge regulation. The way in which the requirements have been incorporated
and the rationale for the approach used to incorporate or specify alternatives
to these requirements are presented below for each of the five management
practices covered in this document.
7.1 LANDFILL COVER REQUIREMENTS
7.1.1 Landfill Cover
The preamble to the current Subtitle D Criteria (44 FR 53456, September
13, 1979) states that the daily application of soils or other suitable cover
materials at monofills serves the following functions:
Controls the escape of odors, litter, and air emissions
Reduces the potential for fires
Reduces rain water infiltration, thereby decreasing leachate generation
and surface and ground-water contamination
Improves the facility's appearance and enhances utilization after
completion
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Controls onsite populations of disease vectors
Discourages scavenging
The requirement to apply daily cover to monofills specifies that "sewage
sludge used or disposed of in a sewage sludge unit shall be covered with cover
materials at the end of each operating day, or at more frequent intervals if
necessary, to control disease vectors, odors, gas venting, and scavenging."
EPA is proposing this requirement for landfill cover because the problems
named above are alleviated in part by cover material. In addition, 19 States
and Territories have some requirement for daily, intermediate, or final cover,
suggesting that this procedure is effective.
7.1.2 Depth of Cover
The Subtitle D Criteria do not specify a required cover depth. It is
suggested that 6 inches of compacted earthen material be applied at the end of
each operating day. The use of earthen material is a standard practice at
most monofills and it is widely accepted that a minimum of 6 inches of
compacted soil will control disease vectors and moisture infiltration.
Nonearthen materials, however, may also meet the requirement and provide the
same protection as earthen material.
7.13 Characteristics of Cover Material
EPA has chosen to make its requirements for daily cover broad, allowing
the States the flexibility to require more-specific practices. Daily cover
requirements that EPA does not address in the rule include daily grading to
control erosion and ponding, and stockpiling fill at the landfill site to last
for a certain period of operation. EPA is allowing the States to specify
these requirements if they choose.
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7.2 DISEASE VECTOR CONTROL REQUIREMENTS
Monofills can provide food, shelter, and breeding areas for disease
vectors, which are animals such as rats, flies, and mosquitoes that can
transmit disease to humans. Some diseases associated with these vectors are
rat-bite fever, leptospirosis, plague, salmonellosis, trichinosis,
murine/typhus fever, malaria, and yellow fever (Noble, 1976; EPA, 1979)
Because monofills can provide an environment for a large number of disease
vectors, EPA requires that owners or operators conscientiously monitor the
disease vector population and follow practices to minimize that population.
EPA further requires monofill owners or operators to employ prevention and
control techniques because accurately measuring specific levels of disease
vectors would be difficult or impossible.
When cover material does not control disease vectors sufficiently,
judiciously applied poisons (insecticides and rodenticides) are an effective
control measure. Insecticide sprays can be used to control fly and mosquito
populations, and rodenticides can be used to control rats. Rodenticides,
however, serve strictly as short-term solutions when the amount of daily cover
is insufficient to prevent rats from flourishing at the monofill. It should
be noted that insecticides or rodenticides must be used according to label
instructions to avoid adverse environmental impacts.
Predatory or reproductive controls can help minimize the vector
population. For example, organisms that feed on mosquito larvae could be
introduced to the facility. Agitating and/or varying the level of standing
water (e.g., leachate ditches) also helps prevent mosquito reproduction. (EPA,
1980) .
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7.3 REQUIREMENTS FOR CONTROL OF EXPLOSIVE GASES
When organic matter in monofills is decomposed by anaerobic bacteria,
explosive gases, predominantly methane, are produced. Anaerobic conditions
arise when the conditions in the voids within the waste materials change from
aerobic to anaerobic and the chemically available oxygen in the refuse is
consumed. The process of gas production is controlled by site-specific
conditions that affect the bacterial population, such as pH, temperature,
moisture, and oxygen content (both gaseous and chemically available). As
landfill gas is generated, pressure builds up within the material. The
pressure then forces the gas to migrate laterally and/or vent to the
atmosphere. The two basic mechanisms by which gases migrate are molecular
diffusion, which is slow, and convective mass transfer, or pressure-induced
flow, which is the predominant mechanism of subsurface gas flow. (GCA, 1986c).
The methane component of monofill gas can create an explosion hazard.
Migrating methane has forced the evacuation of residences and businesses, and
has been responsible for onsite and offsite fires, explosions, property
damage, human injury, and in some cases, death (GCA, 1986c). In addition to
property damage, groundwater contamination and vegetative destruction on site
and on adjacent lands have resulted from landfill gas migration (EPA, 1977a).
For these reasons, EPA established an explosive gas criterion in the
original Subtitle D Criteria under 40 CFR 257.3-8(a) that sets limits on
explosive gases (methane) in facility structures and at the property
boundaries. This standard requires that concentrations of methane not exceed
the lower explosive level (LEL) (5% methane) in soil at the property boundary
and 25% of the LEL (1.25% methane) in onsite structures. Because the human
health standard for methane is greater than the LEL, EPA believes the current
limits provide adequate protection to human health and the environment at the
property boundary and allow for a margin of safety for onsite structures. In
selecting the 25% figure, EPA is using a safety factor recognized as
appropriate for similar structures by other Federal agencies, e.g., in
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regulations established by the Occupational Safety and Health Administration
and the National Fire Protection Codes.
The final method selected to prevent or control the formation and
migration of monofill gases will depend on site-specific conditions, including
soil type, geology, hydrology, and climatic conditions. Numerous methods that
have been used to control gas migration include (EPA, 1977; Raymond Vail and
Associates, 1979):
Permeable trench (gravel trench)
Semipermeable barrier (synthetic liner or clay liner) used with a
gravel trench (trench barrier system)
Venting system with gravel trench or gravel layers (passive landfill
control systems)
Venting with a gas pumping system (active landfill vent control
systems)
A report prepared by Raymond Vail and Associates (1979) provides more detail
on the gas migration control systems discussed above.
A permeable trench that collects and vents the gas is placed at the
perimeter of a. site where gas migration is of most concern. The trench
generally is installed at a depth equal to the depth of the site, but this
approach is not the best approach, because gas may migrate under the trench.
Ideally the trench should be installed to ground water depth or to the depth
of an impermeable geological barrier. The permeable-trench method of venting,
however, has had a low percentage of success in controlling gas migration
(EPA, 1977a; Raymond Vail and Associates, 1979).
The second method, a gravel trench used with a semipermeable liner (a
trench barrier system), provides a more effective barrier than the permeable
trench system. The trench-barrier system should be installed to water table
depth and care must be taken during installation of the liner material to
avoid tears (EPA, 1977a; Raymond Vail and Associates, 1979).
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The third method, a pipe venting system used with a gravel trench (a
passive landfill vent control system), has approximately the same
effectiveness for controlling gas migration as trenches used alone. In
addition, this system is more costly than the above two methods and may be
subject to vandalism (EPA, 1977).
The last method, the pumping system or active landfill vent control
system, provides the greatest effectiveness for gas migration control but is
more costly to install and maintain. This system incorporates a series of
wells (not necessarily installed to the water table) that withdraw the gas
from the landfill or from the area surrounding the landfill. Generally, if
recovered gas is to be used as an energy source, an active vent system is
used. With this method, recovery and migration control are accomplished in a
single process. Where gas migration is to be controlled, pumping wells are
installed between the source of the gas and the threatened building or home.
To avoid continuous operation, systems may be designed to operate only when a
certain concentration of methane is detected (EPA, 1977).
7.4 ACCESS CONTROL REQUIREMENTS
Controlling access to monofills is necessary to prevent injury to the
public from landfill hazards and to ensure that all wastes are properly
disposed. Some sources of potential injury at landfills are (EPA, 1980):
Operations involving heavy equipment and haul vehicles
Waste related hazards; such as pathogens
Accidental or intentional fires
Excavations and other earth moving activities
The potential harm that these hazards pose to facility personnel can be
controlled through proper training, use of safety equipment, and other
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procedures (44 FR 53460, 1979). These controls, however, cannot be imposed on
the general public. The only way to prevent potential harm to the public is
by prohibiting access to monofills by the general public and by strictly
controlling users of the facility on the site (44 FR 53460, 1979).
Control of authorized persons at monofill sites can be achieved using any
of the following measures (EPA, 1980):
Supervising the unloading area
Providing adequate lighting
Posting information and direction signs
Prohibiting scavenging
7.5 RUNON/RUNOFF CONTROL REQUIREMENTS
To minimize liquids entering the monofill waste, runon of liquids from
surrounding areas onto the active area of the unit must be controlled.
Furthermore, runoff of liquids from active portions of a unit must be
controlled, because of the danger that the runoff will contaminate surface
water.
The introduction of liquids is a concern for all phases of monofill
operation; however, the active portion of monofills is of primary concern,
because the irregular fill contours promote waste exposure and infiltration of
fluid into the waste. Other areas of monofill operations have been closed,
covered, and planted with vegetation, thereby immobilizing or diverting any
water near the surface.
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7.5.1 Runon
Two methods of minimizing runon onto the active portion of a monofill are:
(1) making the active portion relatively impervious to water (Lutton, 1982;
McAneny, 1985) and (2) diverting the water away from the active area (Weiss,
1974). The first method is impractical because it requires measures
comparable to those used for permanent closure. Furthermore, because of
relatively rapid changes in the active area, the method could not be
implemented quickly enough to be effective. The second method, runon
diversion, is accomplished either by using natural contours or by constructing
conveyances designed for the amount of water and potential damage associated
with a particular storm event (e.g., 25-year or 50-year storms).
Because storms vary in intensity and duration, a diversion system may be
underdesigned (resulting in inadequate control) or overdesigned (resulting in
unnecessary and costly controls). To contend with the variability of storm
events, EPA has chosen as the design parameter for runon control the peak
discharge of a storm whose intensity and duration is likely to occur once
every 25 years. The Agency has adopted this approach for consistency with the
40 CFR Part 264 standards that require active portions of a hazardous waste
landfill to be protected from the peak discharge of a 25-year storm.
7.5.2 Runoff
Although runon controls protect the active portions of monofills from most
water, they do not prevent the introduction of direct rainfall. Since runoff
produced by rain falling directly on the active portions could be
contaminated, it must not be allowed to leave the site unless applicable
provisions of the Clean Water Act (CWA) are met. These provisions, as
specified in existing regulations, prohibit discharge that violates §402 of
the CWA and nonpoint source pollution that violates a water quality management
plan under §208 of the CWA.
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EPA has chosen the peak discharge of a 25-year storm as the design
parameter for runoff control for the same reasons this parameter was chosen
for runon control. For runoff control, however, both the water in contact
with sludge in the active area and the uncontaminated runoff, must be
collected. The volume of rain falling during a 24-hour period is usually the
measure used in stormwater management design for small watersheds of less than
2,000 acres (SCS, 1985; Viessman et al., 1977). This 24-hour period is an
average that includes short storms of high intensity and long storms of low
intensity.
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APPENDIX A
Partitioning of Pollutants
Between Sludge Solids and Water
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PARTITIONING OF POLLUTANTS
BETWEEN SLUDGE SOLIDS AND WATER
Background
The partition coefficient (or distribution coefficient) is
the quotient of the concentration (e.g., mg/kg) of a specific
pollutant sorbed to solid particles, and the concentration (e.g.,
mg/L) dissolved in the liquid. The leaching mobility of a
pollutant is inversely related to its partition coefficient.
The value of the partition coefficient depends on the
properties of both the chemical being sorbed and the particles
onto or into which the chemical is being sorbed. Typically, the
partition coefficient is measured by (a) equilibrating the
chemical and the particles together in a well mixed aqueous
slurry, (b) measuring the total concentration of chemical in the
slurry, (c) separating the aqueous and particulate phases by
centrifugation, (d) measuring the chemical concentrations in the
supernatant, equating this to the dissolved concentration, and
finally (e) calculating the sorbed concentration by difference.
The estimation of an appropriate value for a pollutant's
partition coefficient is made difficult by the confounding
influence of the particle concentration. Considerable data
indicate that in systems undergoing agitation, the partition
coefficient tends to decrease with increases in the particle
concentration (as noted by DiToro 1985 and by others). Figure 1
illustrates a typical relationship between the measured partition
coefficient and the particle concentration. Both metals and
organics tend to display the illustrated behavior (DiToro et al.
1986).
As shown in Figure 1 for hexachlorobenzene, the partition
coefficient is approximately inversely proportional to the
stirred particle concentration, within the range measured.
Explanations for this behavior generally fall into two groups.
The first attributes the behavior to the confounding influence of
a third phase of nonsettlable sorbing material (for example,
micro-particles, as suggested by Gschwend and Wu 1985). While
the simplicity of this explanation is attractive, it does not fit
all the data, failing particularly in experiments designed to
discern the existence of a third phase (DiToro 1985). The second
group postulates a desorption reaction induced by particle
interactions (DiToro 1985, Mackay and Powers 1987). While this
explanation better fits the data, the molecular basis for it is
speculative.
While the inverse dependency of partition coefficient on
particle concentration is observed using the standard laboratory
protocols involving agitated slurries, it is not observed where
the chemical is equilibrated with the particles in a quiescent
B-l
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0 -
60-
D
O
50-
40-
3 5
Stationary Sol ids O
St irred Sol ids
Log mg/L So Ii ds
Figure 1: Relationship between Hexachlorobenzene Partition
Coefficient (Koc, L/kg organic carbon) and Solids
Concentration. (Data from DiToro et al. 1985)
medium (DiToro et al. 1985). In the absence of particle agita-
tion, the partition coefficient takes on a the value appropriate
for a low solids medium, as shown in Figure 1. Thus, an agitated
leaching test such as the TCLP might often be expected to indi-
cate greater mobility than a stationary leaching test such as the
column method (Appendices A and B, respectively, of EPA 1986).
Given the confounding influence of particle concentration on
the partition coefficient measured in standard laboratory
protocols, accurate estimation of a partition coefficient
appropriate for sludge-borne pollutants in soil or buried sludge
is not an easy task. The degree of dependence on particle
concentration varies somewhat from pollutant to pollutant, and
only occurs within a certain range of particle concentrations
(DiToro 1985). Consequently, while it is expected that the
degree of sorption actually occurring in soil or buried sludge
(stationary particles) would be greater than measured by
laboratory protocols using stirred particles, the magnitude of
the difference cannot be predicted with confidence. In the
subsequent discussion, stirred-particle partition coefficients
will be treated as good estimates of actual partition
coefficients occurring after burial, recognizing that this may
err on the side of safety.
B-2
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Measured Partition Coefficients for Metals
For calculating national criteria for metals, values
measured by Gerritse et al. (1982) were used for the partition
coefficients in the soil underlying a monofill (but not in the
sludge within the monofill). In a series of measurements
Gerritse et al. determined the partitioning of several metals
between a number of solid and liquid phases. The solid phases
consisted of either (a) a sandy soil, having pH 4.5 - 5.0, no
clay, and 3.5 percent total organic matter, (b) a sandy loam,
having pH 7.5 - 8.0, 20 percent clay, and 2.5 percent organic
matter, or (c) digested sludge particles (60 percent organic
matter), obtained from two treatment works, both in an aerobic
condition with pH 5-6, and an anaerobic condition with pH 7 -
7.7. The liquid phases consisted of (a) dilute inorganic
solutions, or (b) sludge liquid supernatant. During
equilibration, the particle concentrations were 160,000 mg/L for
the soils and 20.000 mg/L for the sludges.
U.S. EPA (1985), in generating the environmental profiles,
presented the geometric mean of the range of Gerritse values for
partitioning between sand or sand loam and sludge liquid
supernatant. These partition coefficients are presented in
Table 1. Corresponding values for partitioning between sludge
solids and sludge liquid are also shown in Table 1.
Table 1: Partition coefficients for sludge liquid coupled with
aerobic and anaerobic sludge (Gerritse et al. 1982),
and two soils (U.S. EPA 1985 interpretation of Gerritse
et al. 1982 graphs).
Solid Matrix Arsenic Cadmium Copper Lead Mercury Nickel
Anaerobic Sludge - 59,000 120,000 73,000 - 600
Aerobic Sludge - 1,500 4,200 62,000 - 270
Sandy Loam 19 430 92 600 320 59
Sandy Soil 5.9 15 42 230 580 12
Gerritse et al. (1982) presented the values for sand and
sandy loam graphically; values estimated from the graphs appear
to be subject to roughly a 10 percent uncertainty. While U.S.
EPA (1985) reported three significant digits, the third has no
significance and is not displayed above.
Three features may be noted from the above tabulated values.
First, most of these metals had greater affinity for sandy loam
(with its higher pH and clay content) than sandy soil. Second,
all the metals appear to have greater affinity for sludge than
the two tested soils, although the lesser particle concentration
Gerritse et al. used in the sludge (20,000 mg/L) compared to the
B-3
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soils (160,000 mg/L) may contribute to this result. Third, most
metals are sorbed more strongly under anaerobic conditions than
under aerobic conditions.
In order to supplement the Gerritse et al. (1982) data for
partitioning within sludge, the data of the 40-City Study (Burns
and Roe 1982) were examined. The 40-City Study was intended to
provide information on the fate of priority pollutants in sewage
treatment plants. In this study, pollutant concentrations and
solids concentrations were measured in the sludge and effluent.
Such data is sufficient to calculate a partition coefficient
between sludge solids and wastewater, as they undergo equili-
bration in the aeration tank and secondary clarifier. From
these data, a partition coefficient can be calculated from the
following formula, the derivation of which is provided in the
Supplement to this Appendix:
TT = (ct2 - ctl) / (ctlm2 - c^m,) (1)
where TT denotes the partition coefficient, ctl and ct2 the
pollutant concentration in secondary effluent and sludge
respectively, and ml and m2 the solids concentrations in
secondary effluent and sludge respectively. Note that TT is
called the distribution coefficient, Kd, in the main body of this
Technical Support Document.
Data for four metals, arsenic, cadmium, lead, and mercury
were evaluated in this way. The results are summarized in
Table 2, where the estimated median, 10th percent!le, and 5th
percentile are presented. In summarizing these data a few POTWs,
those with the least contaminated sludge, were not included. The
tabulated partition coefficients thus apply to sludges ranging
from less than typically contaminated to most heavily
contaminated, that is, those of greatest regulatory interest.
Table 2: Summary of Partition Coefficients Determined for All
but the Least Contaminated Sludges.
Arsenic Cadmium Lead Mercury
Estimate >2 ppm >5 ppm >30 ppm >100 ppm >0.5 ppm
Median 2,400 34,000 53.000 34,000 32,000
10th %ile 170 3,000 19,000 8,900 4,900
5th %ile 120 2,000 13,000 3,300 4,300
It should be noted that the above partition coefficients are
for raw, not digested sludge. Nevertheless, in most respects raw
and digested sludge do not differ greatly. Compared to raw
sludge, digested sludge is slightly higher in inorganic material,
lower in organic acids, and higher in pH (Metcalf and Eddy 1972).
B-4
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The Table 2 values are somewhat lower than field estimates
of partition coefficients for natural sediment particles,
summarized in Delos et al. (1984). This difference could stem
the differing compositions of solids. Alternatively the
difference may be an artifact of the high solids concentrations
in the influent to a secondary clarifier, tending to depress the
partition coefficient.
In deriving the national numeric limits, only the soil
partition coefficients of Table 1 were used. None of the sludge
partition coefficients in either Tables 1 or 2 were used. For
metals, the relationship between the pollutant concentrations in
sludge and in leachate was obtained by a different approach,
described below.
Alternative Approaches for Modeling Metals Leachate Generation
Two alternative approaches for modeling metals partitioning
within the sludge are discussed below.
Option A (fixed leachate concentration):
The proposed national numeric limits for metals were derived
assuming that the pollutant concentration in the leachate main-
tains a fixed value independent of the pollutant concentration in
the sludge. The partition coefficient was assumed to be zero.
The dissolved or leachate concentration was assumed to be fixed
at a solubility limit for the metal. The particulate metal in
the sludge was assumed to be composed of metal precipitant,
diluted into but not interacting with the sludge solids. On a
molecular level, the implication is that a dissolved metal ion
would interact with like metal ions present at mg/L levels or
less in the sludge liquid to form a precipitant, but would not
interact with the other sludge solids present at 200,000 mg/L.
In deriving a pollutant numeric limit using such a
framework, one of the key input parameters is the leachate
concentration. For deriving the national numeric limits for
cadmium, copper, and lead, the Agency used a reported maximum
leachate concentration (SCS Engineers [undated], as referenced by
EPA 1978). During development of the proposed regulation, the
original data and reference were not examined, and thus the
reliability of these leachate data is not known. For mercury and
nickel, the leachate (dissolved) concentration was set at the a
maximum observed concentration of dissolved plus particulate
metal in POTW effluent. For arsenic, the leachate concentration
was set arbitrarily.
Once the leachate percolates out of the sludge into the
underlying soil, Option A invokes conventional partitioning
theory to describe pollutant interactions with the soil.
B-5
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Option B (conventional partitioning):
This option applies conventional partitioning theory to
determine the metals leachate concentration in both the sludge
and the underlying soil. This option was evaluated too late in
the regulatory development process to be considered for setting
the national numeric limits for metals. It is, however, directly
parallel to the approach used for setting the national numeric
limits for organic pollutants.
To illustrate application of this approach, the partition
coefficients for sludge liquid and solids, observed by Gerritse
et al. (1982), are used here for cadmium, copper, and nickel.
For lead, the 10th percentile partition coefficient from the 40-
City Study is used here in place of the Gerritse value, in order
to provide greater safety. Lastly, for arsenic and mercury, for
which Gerritse did not report sludge partition coefficients, the
10th percentile values from the 40-City Study are again used.
The pollutant concentration in whole sludge, denoted cs
(mg/kg dry wt), and the dissolved pollutant concentration, cd
(mg/L), in the equilibrated liquid or leachate are related by the
expression:
ca/cd =[*£,+ (1-fJ/Yj / fs (2)
where IT is the partition coefficient (L/kg), fs is the fraction
of solids in the sludge (equal to one minus the fraction liquid),
and 2TL is the density of the leachate (kg/L) . Since the density
of the leachate is essentially 1.0, the above equation simplifies
to:
c3/cd = (TT - 1 + 1/fJ (3)
Thus, for a monofilled sludge having 20 percent solids content,
cs/cd = TT + 4.
Comparison of Options:
The two options are compared in Table 3. The national
numeric limits for these options were computed on a personal
computer using the SLUDGEMAN program. All input parameters were
set at the values specified in the main body of this Technical
Support Document, except for the Option B metals leachate concen-
trations, which were set as described above. In all cases the
model was run iteratively, modifying the input sludge quality
before each successive run, until the sludge quality producing
the maximum allowable exposure (e.g., the MCL) was found by trial
and error.
For Class 1 aquifers the depth of the unsaturated zone was
set at 0.01 m (effectively zero), and the distance in the
saturated zone is by default zero. Option A consistently
produces much lower numeric limits than Option B. It should be
B-6
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noted that with essentially zero opportunity for attenuation of
the peak concentration within the soil, the ground water concen-
tration calculated by Option A does not respond to increases or
decreases in the sludge concentration until one applies the
additional constraint (from Equation 3) that c,/cd=4 when TT=O and
the amount of metal precipitant in the sludge is zero.
Table 3:
Comparison of two options for modeling metal leachate:
(A) fixed leachate concentration, and (B) conventional
partitioning.
As
Cd
Cu
Pb
SLUDGE PARTITION COEFFICIENTS (L/kg)
Option A not applicable
Option B 170 1500 4200 8900
CLASS
Option A
Option B
1 NUMERIC LIMITS (mg/kg)
0.44 0.036 18
19 14 19000
CLASS 2 NUMERIC LIMITS (mg/kg)
Option A 15 6.5 >10000
Option B 42 41 >10000
0.36
780
400
1900
4900
0.0074
8.6
19
51
Ni
270
7
480
>10000
2200
For Class 2 aquifers the depth of the unsaturated zone is
set at 1.0 m, and the distance in the saturated zone set at
150 m. For arsenic, cadmium, lead, and mercury, Option A
produces limits around 3-6 fold lower than Option B. For nickel,
Option A produces a limit at least 5 fold greater than Option B.
For copper, the options are effectively equivalent.
It might be noted that in Option A the sludge concentration,
cs, affects only the leachate pulse time, which in turn affects
the degree of attenuation of the peak concentration that can
occur primarily due to sorptive detention. In Option A the
numeric limit is sensitive to the absolute magnitude of the
leachate concentration, cd. Option A will generate an infinite
numeric limit if the user sets the leachate concentration below
the health effects concentration. In Option B, on the other
hand, the numeric limit is sensitive to the ratio ca/cd (i.e.,
the partition coefficient).
Technically, the principal disadvantage of Option A (fixed
leachate) is that it is difficult to reconcile with the available
data (including Gerritse et al. 1982), and with accepted theory
(as presented for example by Honeyman and Santschi 1988).
Option A lacks a rationale for applying conventional partitioning
to organics but not metals in sludge, and for applying
conventional partitioning to metals in soil but not in sludge.
Option B, on the other hand, incorporates an accepted approach
B-7
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and better uses the available data. Although Option B often
produces less stringent limits than Option A, the use of
partition coefficients measured in agitated slurries should
nevertheless cause Option B to overpredict the leachate
concentration.
Finally, it should be noted that although Option A is
supposed to correspond to the proposed regulation, the numeric
limits calculated by SLUDGEMAN differ somewhat from the numeric
limits presented in the proposed regulation. The numeric limits
of the proposed regulation were computed with a large computer
using an earlier version of the SLUDGEMAN program. The numeric
limits of Option A were computed on a personal computer using the
current version of SLUDGEMAN. Among Class 1 numeric limits,
Option A differs from the regulation for arsenic and copper.
Among Class 2 numeric limits, Option A differs from the
regulation for arsenic, cadmium, lead, and mercury (i.e., all
metals for which an exact value is computed). The precise origin
of this difference is not known.
Alternative Approaches for Modeling Organic Leachate Generation
The two alternatives considered here both set the ratio of
the sludge concentration to the leachate concentration, c,/cd, as
a function of Koc, the organic carbon partition coefficient.
Thus, both options employ conventional partitioning theory. For
each pollutant the value assigned to Koc is presented in Table 4.
For both alternatives only the ratio, not the absolute
magnitudes, of cs and cd affect the numeric limit computed by
SLUDGEMAN.
Option A uses the c,/cd ratios presented in the main body of
this Technical Support Document, and used to generated the
numeric limits in the proposed regulation. For benzene,
chlordane, dimethylnitrosamine, Lindane, TCE, and toxaphene, the
ratio was set by Equation 3, assuming 50 percent organic carbon
in the sludge solids, and 5 percent (not 20 percent) solids
content in monofilled sludge. For benzo(a)pyrene, BEHP, DDT, and
PCB, however, the ratio was set, perhaps questionably, by other
methods noted in Table 4.
Option B determines the cs/cd ratios for all pollutants from
Equation 3. The sludge solids are again assumed to be 50 percent
organic carbon; however, the solids content of the monofilled
sludge is assumed to be 20 percent. The assumption about percent
solids (20% versus 5%) only affects numeric limits for pollutants
with low Koc, that is, pollutants having a significant fraction
dissolved in the sludge liquid.
For the two options, Table 4 compares the ratio c3/cd and
the resulting numeric limit computed by SLUDGEMAN. As this ratio
is a key parameter, changes in this ratio are reflected in
B-8
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proportional or nearly proportional changes in the computed
numeric limit.
As with the metals, it must be noted that Option A, while
intended to correspond to the proposed regulation, differs
slightly for a few pollutants: benzo(a)pyrene, BEHP, and DDT.
Also, for PCB the calculated numeric limits are not used in the
regulation, which instead uses the value from a previous
regulation.
Table 4: Comparison of two options for modeling
organic pollutant leachate generation.
Benz
Koc (L/kg)
BaP BEHP
Chi
Opt A+B 74 5.5E+6 2E+9 1.7E+5
RATIO cs/cd (L/kg) IN SLUDGE
Opt A 55 3.23E+5* 18.4t 85700
Opt B 41 2.75E+6 1E+9 85000
CLASS 1 NUMERIC LIMITS (mg/kg)
Opt A 0.28 97 290 180
Opt B 0.21 830 >lE+5 180
CLASS 2 NUMERIC LIMITS (mg/kg)
Opt A 0.85 300 1600 >lE+4
Opt B 0.63 2600 >lE+4 >lE+4
DDT
5E+6
93**
2.5E+6
DMN Lind
PCB
TCE TOJ
0.04 1080 3.2E+5 198 960
19.4
4.0
0.95
26000
64
>lE+4
0.0019
0.00039
0.07
0.015
564
544
2.3
2.2
75
72
1.6E+6*
1.6E+5
660
65
1700
170
119
103
491
484
0.6 2.5
0.52 2.4
11
9.5
7.6
7.5
For Option A, unless otherwise noted, cs/cd = 0.5 Koc + 19 (approximately).
This assumes that the solids are 50% organic carbon and that the monofilled
sludge is 5% solids. The exceptions are as follows:
* BaP and PCB, origin of c3/cd unknown, perhaps erroneous;
** DDT, c3 set at a maximum reported sludge concentration, cd set at a
reported maximum effluent concentration for dissolved plus particulate
pollutant (neither from the 40-City Study); and
t BEHP, cs/cd set arbitrarily.
For Option B, in all cases, c,/cd =0.5 Koc + 4. This assumes that the solids
are 50% organic matter and that the monofilled sludge is 20% solids.
B-9
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SUPPLEMENT TO APPENDIX A
Calculating Partition Coefficients
from Concentrations of Pollutants and Solids
Measured in Sewage Treatment Plants
This discussion presents a theoretical framework for
calculating the partition coefficient from pollutant and solids
concentrations in POTW sludge and effluent. This framework was
was constructed starting from model principles set forth by
HydroQual (1981), as described also by Delos et al. (1984) and
HydroQual (1986). The basic principles, originally applied to
natural waters, are applied here to the processes occurring in
the secondary clarifier of a municipal wastewater treatment
plant.
In this approach the liquid and solid phases are assumed to
equilibrate within the wastewater aeration tank (or equivalent
treatment process). The secondary clarifier (illustrated in
Figure 2) then produces a sufficient degree of solids separation
to allow the partition coefficient to be calculated from the
measured quality in the upper and lower portions of the
clarifier. The mathematical derivation is somewhat complicated
because the solids separation is incomplete: the effluent
retains some solids, while the sludge retains much water.
Consequently, it is not assumed that the effluent contains only
dissolved pollutant. Nor is it assumed that the sludge contains
only particulate pollutant.
The following nomenclature is taken from the above
references:
cti> Ct2: Total concentration of pollutant in effluent and sludge
respectively [|ag/L] .
cdl, cd2: Concentration of dissolved pollutant in effluent and
sludge respectively [|ag/L].
cPi> CP2: Concentration of pollutant bound to particles in
effluent and sludge respectively, expressed per unit
volume [ (ag/L] .
rls r2: Concentration of pollutant bound to particles in
effluent and sludge respectively, expressed per unit
weight [ng/kg].
mls m2: Concentration of solids in effluent and sludge
respectively [kg/L].
Partition coefficient applicable the effluent and
sludge respectively [L/kg]. This parameter is the same
as Kd, the distribution coefficient, the term used in
the main body of this Technical Support Document. By
definition, IT = r/cd.
B-10
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Flow from
aeration
tank
Effluent with
measured n^
and ctl
Sludge with measured <-
m2 and ct2
Figure 2: Schematic of Secondary Clarifier,
To determine the relationship between the partition
coefficient and the solids and pollutant concentrations in
effluent and sludge, one may begin by noting that cti = cpi + c
and cpi = rimi =
dissolved is given by:
cdl/ctl =
It then follows that the fraction
cd2/ct2 =
l + TT2m2)
The following key assumptions are now made. First, it is
assumed that
= ir
in keeping with the idea that equilibration
occurs prior to entry to the secondary clarifier. Hereafter the
partition coefficient applicable to both the effluent and the
sludge will simply be denoted IT. (The effect of potential error
in this assumption is discussed later. ) Second it is assumed
that the rate of decay of pollutant in the sludge is zero, which
should be appropriate for metals. Under these conditions,
r1 = r2 and cdl = cd2, as discussed by Delos et al. (1984), among
others. Consequently, interchanging cdl and cd2 in the above
equations yields:
l + nm2)
l + irm2)
cdl/ct2 =
Since cdi = cti - cpi, where cpl = rjrv,, then:
(ct2-m2r2)/ctl = l/(l+-rrm1) (c^-n^rj
Solving for r±:
r2 = {ct2 - c^/tl+irmj } / m2 r, = {ctl
Since r1 = r2, the equations can be combined:
ct2/(
m
= {ct
ct2/( l + Trm2
This equation contains the partition coefficient, TT , whose value
we wish to calculate, and the four measured parameters, ctl and
ct2 (the total concentration of the pollutant in effluent and
sludge) and m^ and m2 (the solids concentrations in effluent and
B-ll
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sludge). As written, the value of IT could be determined
numerically, by trial-and-error iteration.
Alternatively, a simple analytical solution for TT can be
produced as follows. Algebraic rearrangement of the above
equation yields:
ct2 (iT^^mj + 2irm1m2 + im^2 + n^ + m2)
= ctl (TT2m22ma + 2irm1m2 + Trm22 + n^ + m2)
In application to the secondary clarifier of a sewage treatment
plant, it should be noted that m1«m2. That is, the solids
concentration in effluent is always much less than that in
sludge, as evidenced by the data of the 40 City Study.
Consequently, the additive n^ term is always an insignificant
portion of the sum, and can thus be dropped from both sides of
the equation. Furthermore, on the left side of the equation,
irmj2 must always be insignificant compared to 2Tim1m2, and may
therefore be dropped. On the right side of the equation, 2irm1m2
is always insignificant compared to TTm22, and therefore could be
dropped. However, it is more convenient to drop only one-half
the magnitude of 2irm1m2, thereby leaving irm^ in its place.
These approximations yield:
ct2 (TT2m12m2 + 2irm1m2 + m2) = ctl (TT2m22m1 + Trm.[m2 + irm22 + m2)
which, by factoring out m2, reduces to:
ct2 (ir2!!^2 + 2'nm1 + 1) = ctl (TT2m2m1 + TriT^ + Trm2 + 1)
This equation simplifies to:
ct2 (Tim, + I)2 = ctl (nm2 + l)(Trm1 + 1)
or:
ct2 (Trm, + 1) = ctl (Trm2 + 1)
Algebraic rearrangement yields a solution for TT :
f = (c« - ctl) / (ctlm2 - ct2ma)
This equation should be valid provided that partitioning has
approached equilibrium within the sewage treatment facility,
provided that the partition coefficient maintains the same value
in the effluent and the sludge, and provided that the
concentration of solids is much less in the effluent than in the
sludge.
The assumption that tr maintains the same value in both
effluent and sludge is important. If the partition coefficient
were to display an inverse relationship with the concentration of
solids, then n1 would exceed ir2, and this analysis would tend to
B-12
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overestimate the partition coefficient applicable to sludge. As
noted previously, such an inverse relationship is often found in
measurements in media undergoing motion due to mechanical mixing.
However, the partition coefficient in a stationary sediment
medium having high solids concentration appears to maintain the
value it would have in a low solids medium (DiToro et al. 1985,
HydroQual 1986). As sludge is a stationary medium after
disposal, the partition coefficient applicable to a low solids
environment should be appropriate. In that case, the value
calculated here should not be an overestimate.
Data for four metals, arsenic, cadmium, lead, and mercury
were evaluated in this way. Table 5 presents the data and the
calculated results.
The first column of the table identifies the POTW by number.
In the column following the POTW identification number, an "s"
indicates that a single process was involved in separating the
solids from the liquid. In nearly all cases this means that the
data for the effluent and the sludge leaving the secondary
clarifier were used. However, for a few plants it means that
data for the sludge decant liquid and the dewatered sludge were
used. An "n" following the identification number indicates that
more that one process was involved in separating solids from
liquid, usually meaning that the sludge measurements were for a
mixture of primary and secondary sludge. The potential for
confounding influences seem somewhat less where only a single
process is involved in the solids separation.
The table then presents the solids concentrations (mg/L) and
pollutant concentration (fjg/L) for both effluent and sludge, as
presented by Burns and Roe (1982). Where the pollutant was
undetected in the effluent, the detection limit followed by a.
minus sign, indicating "less than", is tabulated. The pollutant
concentration in sludge, converted to mg/kg, was calculated from
the quotient of pollutant and solids concentrations in sludge.
The partition coefficient calculated for each metal is then
tabulated. Two things should be noted here. First, where the
pollutant was undetected in the effluent and portrayed as being
less than the detected limit, all that can be said about the
partition coefficient is that it is greater than the calculated
value. A plus sign following the tabulated value denotes
"greater than". Second, where the partition coefficient is very
large, above 10s - 106 L/kg, nearly all of the pollutant in both
the sludge and the effluent is bound to particulate matter,
little of it is dissolved. Consequently, this type of analysis
is unable to discern the exact value of very large partition
coefficients. Where the data indicate a very large partition
coefficient, a value of IxlO6 is reported in Table 5. Placing
this upper limit on the reported partition coefficient has no
effect on the median and lower percentile values, however.
B-13
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For cadmium, a relationship between the degree of sludge
contamination and the partition coefficient was clearly apparent.
The less contaminated sludges tended to have lower partition
coefficients; the more contaminated sludges tended to have higher
partition coefficients. For lead, arsenic, and mercury this
tendency was not as strong. As the main regulatory interest is
in typically contaminated sludges or worse, the least
contaminated sludges were disregarded in statistically
summarizing the results. For cadmium, POTWs with less than 5
mg/kg were disregarded, leaving 34 of 46 in the analysis. For
lead, POTWs with less than 100 mg/kg were disregarded, leaving 44
out of 49 in the analysis. For arsenic, those with less than 2
mg/kg were discarded, leaving 29 out 34 in the analysis. For
mercury, those with less than 0.5 mg/kg were disregarded, leaving
41 out of 45 in the analysis. It might be noted that eliminating
the least contaminated sludges also has the effect of eliminating
the samples having the greatest relative measurement error.
The results were previously summarized in Table 2, which
presented the estimated median, 10th percentile, and 5th
percentile. For these estimates, "greater than" and "less than"
values were disregarded whenever it was not possible to know
whether the true value was higher or lower than the median or
percentile value.
B-14
-------
Table 5: Observed Concentrations and Calculated Partition
Coefficients for Four Metals, 40-City Study.
1
Plant
1 s
2 n
3 n
4 n
5 n
6 n
7a n
7s s
8a n
8s s
9 s
10 s
11 s
12 s
13 s
14 s
15 n
16 n
17 s
18 s
19 s
21 s
22 n
23 s
24 s
27 s
28 s
29 s
30 s
31 s
32 s
33 s
34 s
35 s
36 B
37a s
37t s
38 s
39 s
40 3
51 s
52 n
53 s
54 s
57 n
58 n
59a n
59s s
60 n
Solids --I
Eff
mg/L
20
9
12
43
12
27
18
2877
69
273
14
16
14
14
13
9
27
16
9
21
29
29
22
18
31
11
24
44
7
19
15
14
11
22
38
7
22
5
20
54
9
23
9
50
49
11
15
86
33
Sludge
mg/L
6300
21714
31859
59667
26433
51782
35057
26313
76755
189100
6281
555
1396
9017
28422
5200
126667
30330
3661
11334
16500
17531
37500
1215
340
6200
8750
2513
8977
5710
2007
17233
3068
22537
4110
3703
1348
2482
575
1190
28317
58400
4694
5360
32430
43124
29974
29974
43000
i
i
Eff
ug/L
4
2
1
1
1
65
5
139
2
2
2
1
8
15
2 -
2 -
2 -
2
4
2 -
2
2 -
2 -
14
2
2
7
2
2
2
5
2
2
1
6
2
16
2
1
2
4 -
2 -
2 -
4
96
3
100
100
2
fa
\*a
dmium
Sludge
ug/L
344
305
42
518
385
79833
498
313
450
780
152
24
29
9105
155
26
585
560
357
143
2727
131
150
365
7
74
597
10
26
48
15
13
5
516
6
1168
433
210
16
12
78
23
200
14
45483
458
84
84
241
mg/kg
55
14
1
9
15
1542
14
12
6
4
24
43
21
1010
5
5
5
18
98
13
165
7
4
300
21
12
68
4
3
8
7
1
2
23
1
315
321
85
28
10
3
0
43
3
1402
11
3
3
6
i
1
Part Coef
1
7
1
1
1
6
3
6
3
4
1
1
2
1
2
2
2
1
3
7
1
4
2
3
1
6
1
1
1
4
1
3
4
4
0
1
3
5
S
5
6
1
2
4
5
3
3
L/kg
.9E+04
.4E+03 +
.3E+03
.4E+04
.8E+04
.6E+04
.OE+03
.3E+01
.7E+03 +
.7E+03 +
.4E+04
.OE+05
.OE+03
.OE+05
.8E+03 +
.4E+03 +
.5E+03 +
.1E+04
.1E+04
.2E+03 +
.OE+05
.1E+03 +
.1E+03 +
.4E+04
.1E+04 +
.2E+03 +
.3E+04
.7E+03 +
.4E+03 +
.4E+03 +
.OE+03 +
.2E+02 +
.9E+02 +
.6E+04
.OE+00
.OE+05
.5E+04
.3E+04 +
.9E+04
.8E+03 +
.6E+02 +
.8E+02 +
.6E+04 +
.8E+02
. 1E+04
. 7E+03
. 1E+03 +
i
1
Eff
ug/L
20 -
3
30
53
4
18
47
1701
85
192
17
20
127
4
20
11
20
20
11
23
50
50
54
9
50
50
34
50
50
40
50
50
50
50
64
50
50
50
11
50
14
40
40
92
500
86
33
200
40
I fi^rl
Sludge
ug/L
1594
7386
1475
41000
8967
9667
44167
6133
98750
95250
2250
288
682
1917
10467
1817
14900
10600
1187
5200
3450
5033
77333
1060
155
1352
11400
1063
1557
3700
2214
3217
5017
7175
518
1800
1065
1087
100
55
7493
6308
840
430
194667
30134
2167
2167
18875
mg/kg
253
340
46
687
339
187
1260
233
1287
504
358
519
489
213
368
349
118
349
324
459
209
287
2062
872
456
218
1303
423
173
648
1103
187
1635
318
126
486
790
438
174
46
265
108
179
80
6003
699
72
72
439
I
Part Coef
L/kg
1.7E+04 +
1. OE+05
1 .5E+03
2.9E+04
1. OE+05
1 .4E+04
5.2E+04
1.6E+02
1. OE+05
9.2E+03
3.0E+04
4.1E+04 +
3.3E+03
1. OE+05
2.4E+04 +
4.4E+04
7. OE+03 +
2.4E+04
4.0E+04
3.4E+04
4.7E+03 t
6.8E+03 +
1. OE+05
1. OE+05
8.6E+03 +
4.4E+03 +
1. OE+05
1 . 3E+04 +
3.4E+03 +
2.3E+04 +
3.2E+04 +
3.9E+03 +
5.1E+04 +
7.4E+03 +
1.9E+03
l.OE+04 +
2.3E+04 +
8.7E+03 +
2.1E+04
8.8E+01 +
2.3E+04
2.9E+03 +
4.4E+03 +
7.2E+02
2.9E+04
8.9E+03
2.2E+03
3.4E+02 +
1.7E+04 +
B-15
-------
Table 5 (Continued)- Data from 40-City Study.
1 arsenic 1 |
Plant
1 s
2 n
3 n
4 n
5 n
6 n
7a n
7s s
8a n
8s s
9 s
10 s
11 s
12 s
13 s
14 s
15 n
16 n
17 s
18 s
19 s
21 s
22 n
23 s
24 3
27 s
28 s
29 s
30 s
31 s
32 s
33 s
34 s
35 s
36 a
37a s
37t s
38 s
39 s
40 s
51 s
52 n
53 s
54 3
57 n
58 n
59a n
59s s
60 n
Eff
ug/L
50 -
50 -
2
50 -
50 -
50 -
3 -
56
50 -
500 -
2
50 -
50
1
50
12
50
50 -
50 -
9
50
50 -
50 -
50 -
50 -
50 -
3
10 -
50 -
50 -
50 -
4
50 -
50 -
50
50
50
1
1
3
1
2
20
1
1
1
Sludge
ug/L
63
149
138
403
78
212
332
207
695
1463
19
19
192
38
1247
868
16
57
131
360
53
1
19
30
15
99
36
55
228
25
104
23
4
6
11
1
31
403
615
4
8
216
122
13
13
52
mg/kg
10
7
4
7
3
4
9
8
9
8
3
2
7
7
10
29
4
5
8
21
1
1
3
3
6
11
6
27
13
8
5
6
1
4
4
2
26
14
11
1
1
7
3
0
0
1
Part Coef
4.
9.
2.
1.
2.
6.
3.
1.
1.
1.
1.
1.
7.
1.
2.
1.
9.
2.
1.
1.
2.
2.
2.
4.
1 .
1.
1.
7.
1.
3.
1 .
4.
4.
I .
L/kg
1E+01 +
1E+01 +
2E+03
2E+02 +
1E+01 +
3E+01 +
3E+03 +
7E+02
7E+02 +
OE+01 +
4E+03
OE+02 +
6E+03
9E+02 +
4E+03
2E+01 +
9E+01 +
4E+03
6E+00 +
1E+02 +
OE+03
3E+03 +
1E+02 +
8E+01 +
2E+03
6E+04
4E+04
1E+01
4E+03 +
9E+03
2E+02
OE+02
2E+02 +
2E+03
Eff
ng/L
57
1000 -
450
200
1000
1000
200 -
225
1000 -
60
167
200 -
200
1000
200
183
200
200
100
233
200
200
50
133
650
200
1000
300
133
150
1000
133
267
200
217
567
1000
1000
167
1000
500
500
67
233
1000
nercury 1
Sludge
ng/L
3286
29250
360000
486667
205000
140500
172500
505000
46333
12000 -
8167
17167
33000
21500
142000
35167
24167
4833
79167
65333
60667
9000
49667
53167
7167
15333
6167
18000
500
6000
5333
2167
5000
1833
5000
5000 -
60000
158200
100333
33333
194667
51833
27500
27500
284750
ng/kg
151
918
6033
9398
5848
5340
2247
2671
7377
21622
5850
1904
1161
4135
1121
1159
6601
426
4798
3727
1618
26471
8011
6076
2852
1708
1080
8969
163
266
1298
585
3709
739
8696
4202
2119
2709
21375
6219
6003
1202
917
917
6622
Part Coef
2
9
3
1
6
1
5
1
8
1
6
1
6
4
6
7
4
2
1
3
9
1
1
1
4
9
9
5
9
1
1
4
1
3
1
1
2
2
1
8
2
2
1
5
8
L/kg
.7E+03
.OE+02
.2E+04
.OE+05
.5E+03
.OE+05
.OE+04
.OE+05
.OE+03
.OE+05
.7E+04
.1E+04
.2E+03
.1E+03
.6E+03
.OE+03
.7E+04
.1E+03
.OE+05
.OE+04
.BE+03
.OE+05
.OE+05
.OE+05
.9E+03
.OE+03
.2E+02
.3E+04
.1E+02
.8E+03
.1E+03
.3E+03
.9E+04
.4E+03
.OE+05
.1E+04
.1E+03
.9E+03
.OE+05
.8E+03
. 9E+04
.4E+03
.7E+04
.9E+03
.4E+03
+
+
+
-
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
B-16
-------
References
Burns and Roe Industrial Services Corp. 1982. Fate of Priority
Pollutants in Publicly Owned Treatment Works. EPA 440/1-82/303.
Office of Water Regulation and Standards, U.S. Environmental
Protection Agency, Washington, DC.
Delos, C.G., W.L. Richardson, J.V. DePinto, R.B. Ambrose, P.W.
Rodgers, K. Rygwelski, J.P. St. John, W.J. Shaughnessy, T.A.
Faha, W.N. Christie. 1984. Technical Guidance Manual for
Performing Waste Load Allocations, Book II Streams and Rivers,
Chapter 3 Toxic Substances. EPA-440/4-84-022. Office of Water
Regulations and Standards, U.S. Environmental Protection Agency,
Washington, DC.
DiToro, D.M. 1985. A Particle Interaction Model of Reversible
Organic Chemical Sorption. Chemosphere 14:1503-1538.
DiToro, D.M., J.S. Jeris, and D. Ciarcia. 1985. Diffusion and
Partitioning of Hexachlorobiphenyl in Sediments. Environ. Sci.
Technol. 19:1169-1176.
DiToro, D.M., J.D. Mahony, P.R. Kirchgraber, A.L. O'Bryne, L.R.
Pasguale, and D.C. Piccirilli. 1986. Effects of
Nonreversibility, Particle Concentration, and Ionic Strength on
Heavy Metal Sorption. Environ. Sci. Technol. 20:55-61.
Gerritse, R.G., R. Vriesema, J.W. Dalenberg, and H.P. DeRoos.
1982. Effect of Sewage Sludge on Trace Element Mobility in
Soils. J. Environ. Qual. 11:359-364.
Gschwend, P.M., and S. Wu. 1985. On the Constancy of Sediment-
Water Partition Coefficients of Hydrophobic Organic Pollutants.
Environ. Sci. Technol. 19:90-96.
Honeyman, B.D., and P.H. Santschi. 1988. Metals in Aquatic
Systems. Environ. Sci. Technol. 22:862.
HydroQual, Inc. 1981. Analysis of Fate of Chemicals in
Receiving Waters, Phase I. Prepared for the Chemical
Manufacturers Association, Washington, DC.
HydroQual, Inc. 1986. Technical Guidance Manual for Performing
Waste Load Allocations; Book IV Lakes, Reservoirs and
Impoundments; Chapter 3 Toxic Substances Impact. EPA-440/4-87-
002. Office of Water Regulations and Standards, U.S.
Environmental Protection Agency, Washington, DC.
Mackay, D., and B. Powers. 1987. Sorption of Hydrophobic
Chemicals from Water: a Hypothesis for the Mechanism of the
Particle Concentration Effect. Chemosphere 16:745-757.
Metcalf and Eddy, Inc. 1972. Wastewater Engineering. McGraw-
Hill, New York.
B-17
-------
SCS Engineers [undated]. Selection and Monitoring of Sewage
Sludge Burial Case Study Sites. As referenced by U.S. EPA 1978.
Process Design Manual Municipal Sludge Landfills. EPA-625/1-78-
010, SW-705.
U.S. Environmental Protection Agency. 1985. Environmental
Profiles and Hazard Indices for Constituents of Municipal Sludge.
Office of Water Regulations and Standards, Washington, DC.
U.S. Environmental Protection Agency. 1986. Development of Risk
Assessment Methodology for Municipal Sludge Landfilling.
Environmental Criteria and Assessment Office, Cincinnati, OH.
B-18
-------
APPENDIX B
Sensitivity Analyses on Selected Model Parameters
-------
Results of Sensitivity
Analyses for Sewage Sludge
Landfill ing
December 1987
Prepared by
G. W. Dawson
C. A. Newbill
ICF Technology, Inc.
Richland, Washington
for
Wastewater Solids Criteria Branch
U.S. Environmental Protection Agency
-------
Results of Sensitivity
Analyses for Sewage Sludge
Landfill ing
EPA is required, under Section 405(d) of the Clean Water Act, to
develop regulations for the use and disposal of sewage sludge. One of
the disposal options is landfill ing. The regulation regarding
landfill ing uses the SLUDGEMAN model to predict the maximum allowable
concentrations of pollutants in sewage sludge that will not
detrimentally affect an MEI (Most Exposed Individual) who drinks ground
water from the site 100% of the time over a 70 year lifespan.
This document summarizes the results of sensitivity analyses
conducted on the model showing how maximum allowable sludge
concentrations vary with sludge and site-specific factors. Initially a
base case scenario was run against which all subsequent runs were
compared. The input parameters for the baseline case are shown in
Tables 1 through 4. For each sensitivity run, selected parameters were
varied and these are shown in Table 5. Table 6 shows the health
effects levels against which final concentrations were compared in
order to calculate allowable dry weight sludge concentrations for each
chemical.
The seven parameters varied were: 1) distance to the point of
compliance, 2) depth to ground water, 3) net recharge, 4) aquifer
thickness, 5) groundwater velocity, 6) groundwater chemistry, and 7)
sludge moisture content. One would expect that increasing the distance
to a downgradient point of interest would result in lower chemical
concentrations there, thus allowing higher chemical concentrations in
the sludge. The changes result in more time and space for dispersion
of the chemicals in the aquifer over the greater distance. Conversely,
decreasing the distance to a point downgradient from the landfill
decreases chemical dispersion and increases chemical concentrations.
Thus lower initial concentrations are allowed in the landfill if final
concentrations at the downgradient point are to be kept under health
effects levels.
For a similar reason, one would expect increasing the depth to
groundwater and thickness of the aquifer would allow more dispersion,
thus reducing the final chemical concentrations and allowing higher
concentrations in the sludge. Conversely, decreasing the depth to
groundwater or aquifer thickness have the opposite effect; that of
decreasing dispersion and thus producing higher outflow concentrations
and allowing lower initial concentrations in the sludge.
Increasing the depth to groundwater or distance to the compliance
point can also decrease outflow concentrations by allowing greater time
for chemicals to degrade. For most of the chemicals simulated,
degradation is not a significant factor, but it is for some of the
organics, namely Chlordane, DDT, DMN, Lindane, and TCE. On the other
hand, decreasing the distance to a downgradient point or decreasing the
depth to groundwater reduces the chemical travel time and thus allows
less degradation to take place. This results in higher outflow
concentrations and lower allowable sludge concentrations if outflow
concentrations are to be kept under health effects levels.
-------
Sludgeman uses net recharge to determine the rate at which
leachate leaves the landfill and travels through the unsaturated zone.
Therefore, increasing recharge has the effect of increasing leach rates
from the landfill and decreasing unsaturated zone travel times. This
should increase chemical concentrations at a downgradient point of
interest, other factors being constant. Conversely, lower recharge
causes slower leach rates and higher travel time in the unsaturated
zone. This creates slower leach rates into the saturated zone, thus
allowing greater dilution from the generally higher flow rates in that
zone. Also, the longer travel time in the unsaturated zone allows
greater degradation there for chemicals which are degradable.
Increasing groundwater velocity creates a greater volume of water
into which each year's recharge is mixed. Hence, higher velocities
lead to more dilution and greater allowable sludge concentrations while
slower velocities have the opposite effect. For degradable chemicals,
there is a countervailing effect because the slower velocities allow
more travel time for degradation. Groundwater geochemistry affects
inorganic constituent solubilities and thereby controls groundwater
concentrations for some contaminants. In general, reducing conditions
and lower acidities reduce solubilities. Finally, sludge moisture
content changes the overall solids content of a given volume of sludge
and, therefore, its inventory of contaminants. As sludge moisture
increases, allowable sludge concentrations increase and conversely,
allowable levels go down with moisture content.
The results of the Sludgeman sensitivity runs were in agreement
with these concepts. There were cases, however, in which changing a
hydrologic parameter did not seem to produce the expected result. This
occurred, for example, when the depth to groundwater was increased from
the base line case of 0 meters to 10 meters. For some chemicals--
benzene for example -- no decrease in outflow concentration was found.
This was due to the extremely long release time from the landfill for
this chemical. The release time from the landfill was so much greater
than the travel time across the unsaturated zone, that the unsaturated
zone didn't have enough time or distance to reduce the peak
concentration below that leaching directly from the landfill. The time
of peak outflow concentration at the downgradient point of interest was
significantly increased, but the peak concentration was the same. The
principles of hydrology were still in effect, but the unsaturated zone
was just not large enough to disperse the very long pulse below its
peak concentration.
Another example is the concentration of BEHP. BEHP has a very
high Kd in the unsaturated zone, so one would expect the presence of an
unsaturated zone to greatly influence the outflow concentration
downgradient from the landfill. This is because the pulse from the
landfill spends so much time in the unsaturated zone, that there is
ample opportunity to disperse the peak below the leachate concentration
from the landfill. When we simulate a 1 meter thick unsaturated zone,
we indeed find this to be the case. Outflow concentrations are reduced
by a factor of over 100. But when we increase the unsaturated zone
thickness to 5 meters and then 10 meters, we find very little change in
the BEHP concentration at 150 meters downgradient. The reason is that
although we are continuing to significantly decrease the groundwater
-------
concentration at 150 meters, the groundwater concentration is no longer
the dominant influence in the total final concentration. The vapor
concentration is now the controlling factor. Therefore, decreasing the
groundwater concentration has little effect on the total exposure at
the point of interest.
In addition to demonstrating the direction and magnitude of
effects arising from changes in input parameter values, the data
provided here can be used to select allowable sludge concentrations for
contaminants for settings that differ from the base cases. In order to
do this, the applicant should refer to Table 5 and find the set of
conditions which matches the characteristics of the site of interest.
The right hand column then indicates which table of values will provide
the controlling sludge conditions for that site. For example, if the
site of interest is situated so that the exposure point is 150 meters
from the site boundary, has an annual recharge level of 0.5 m/yr, an
aquifer thickness of 76.8 meters, a groundwater velocity of 100 m/yr,
soil organic content of 0.0001, and a depth to groundwater of 10
meters; the site is equivalent to case S7-150T1, Table 30. The
allowable sludge concentrations for that case are shown in the table.
When conditions are not precisely the same as a case run here, the
closest more conservative case should be selected. In general, the
conservative case is identified by rounding down on distance to
exposure point, depth to groundwater, soil organic content, aquifer
thickness, and groundwater velocity. Recharge should be rounded up.
If there are doubts as to the case that is most appropriate, review all
similar cases and use the most restrictive allowable sludge criteria.
The sensitivity analyses were compared for the 10"** level health
effects. The 10"^ and 10"° health effects levels were also compared
against, but it was found that the allowable dry weight concentrations
for those levels differed from the 10"^ level by simple multiples of
10. For example, the 10~5 health effects level allowed 1/10 the level
of sludge concentration as the 10"^ level, and the 10"° level allowed
1/100 the level of sludge concentration. Therefore, once the allowable
dry weight concentrations for the 10"^ health effects level were
calculated, those for the 10"^ and 10"° levels could be immediately
calculated by dividing by 10 and 100, respectively.
The reason is that for the organics, leachate concentration is
linearly related to dry weight concentration in the sludge. Therefore,
when the dry weight concentration is changed, the leachate
concentration is changed proportionally. This means the release time
remains constant, and as well as the peak travel time, causing the
effects of dispersion and degradation remain the same. The resulting
concentration at a monitoring point is then directly proportional to
the change in leachate and dry weight concentrations.
The input parameters and varied parameters were supplied by EPA.
Many came from the EPA Hazard Profiles for 1985.
The designations for the sensitivity runs are descriptive of the
parameters varied. The designations are shown in Table 5 along with
the parameters varied. The designations are also listed at the top of
each sensitivity run result table as a quick indication of what
parameters were varied for that run and what values were used. Most
designations begin with an "S" indicating a sensitivity run, the base
-------
case simulations for each distance beginning with a "B". The number 4
immediately following the "B" for the base case runs indicates the case
was run for the 10"^ health effects level. The number immediately
following the "S" for the sensitivity runs indicates basic parameters
changed for that sensitivity run. These codes can briefly be described
as:
B4 - Base Case at 10-4 health effects level
S7 10 meters to groundwater, FOC = 10-4
S8 10 " " " , FOC = 10-2
S9 - 5 meters to groundwater, FOC = 10-4
S10 - 5 " " , FOC = 10-2
Sll 5 meters to groundwater, FOC = 10-4
S12 - 1 " , FOC = 10-2
S13 0.25 m/y recharge instead of 0.5
S14 - 0.00635 m/y recharge
S15 - 1000 m/y groundwater velocity instead of 100
S16 - 10 m/y
S17 - 1 m/y " "
S18 - 560 m aquifer thickness instead of 15 m
S19 - 78.6 m " "
S20 - 5.0 m " " " " " "
S21 - eh = 150 instead of 500
S22 eh = -200 " " " , ph = 7.0 instead of 6.0
S23 sludge moisture capacity = 0.95 instead of 0.80
S24 - sludge " " " 0.60
The S7 through S12 cases have additional sensitivity runs
associated with them. Combinations of net recharge and aquifer
thickness were also varied, in addition to the basic variances in depth
to groundwater and FOC. These changes were indicated with the
additional designations of Rl, R2, Tl, and T2 indicating
Rl - net recharge = 0.25 m/y instead of 0.5 m/y
R2 - net recharge = 0.00635 m/y
Tl - aquifer thickness = 78.6 m instead of 15 m
T2 - aquifer thickness = 5.0 m.
Thus S7-150R1T2 indicates the depth to groundwater was 10 meters,
distance to a monitoring well 150 meters, net recharge 0.25 m/y, and
aquifer thickness 5 meters.
In Table 5, all sensitivity parameter values are listed for the
first simulation. For subsequent sensitivity analyses, only values
changed for each run are listed, values remaining unchanged are left
blank. Thus it is easy to see which parameters are changing by the
values being listed. All parameter values are listed for the first
simulation on a continued page.
-------
Table 1.
Baseline Input Concentrations,
Parameter
Leachate
Concentration
(mg/1 ) As
Cd
Cu
Pb
Hg
Ni
Benzene
B(A)P
BEHP
Chlordane
DDT/DDE/DDD
DMN
Lindane
PCB
Trichloroethylene
Toxaphene
Value (mq/1)
1 (a)
0.2 (b)
37 (b)
10 (b)
0.69 (f)
3.4 (c)
0.12 (d)
0.000006 (d)
25 (a)
0.00014 (d)
0.01 (e)
0.014 (d)
0.00039 (d)
0.0000018 (d)
0.022u(d)
0.15 (d)
Parameter
Dry Sludge
Concentration
(mg/kg) As
Cd
Cu
Pb
Hg
Ni
Benzene
B(A)P
BEHP
Chlordane
DDT/DDE/DDD
DMN
Lindane
PCB
Trichloroethylene
Toxaphene
Value (mq/Kq)
20.75 (a)
88.13 (b)
5600. (b)
1070. (a)
5.85 (a)
920. (a)
6.6 (a)
1.935 (a)
459. (a)
12. (d)
0.930 (d)
0.272 (e)
0.220 (d)
2.90 (d)
17.85 (d)
10.8 (d)
(a) Estimate based on estimated
liquid concentration to require
at least one year to deplete mass
in sludge.
(b) Indicates value was the max-
imum reported for leachate from
a sludge monofill. (EPA, 1978)
(c) Maximum effluent reported for
municipal wastewaters. (Barth et.
al., 1965)
(d) Indicates value was derived
from the sludge concentration and
the Koc at 5% solids and 50%
organic solids.
(e) Indicates
imum effluent
(EPA, 1978)
value was the max-
value reported
(f) Value recommended by Betsy
Southerland, June, 1987.
(a) Indicates value for 95th
percentile sludges surveyed.
(EPA, 1985a)
(b) Indicates
maximum value
surveys.
value was
between a
an average
number of
(c) Value selected to support
reported leachate level.
(d) Indicates value was the maximum
value reported.
(e) Indicates value was the mean
value reported.
-------
Table 2.
Baseline Values for the Unsaturated Zone.
Sludge Moisture Content 0.80
Sludge Storage Capacity 0.90
Sludge Density 1025
Net Recharge 0.5
Landfill Width 100
Landfill Length 100
Depth to Ground Water 0
Inorqanic Kd's (1/kq)
As 5.86
Cd 14.9
Cu 41.9
Pb 234.
Hg 322.
Ni 12.2
kg/kg
kg/ kg
kg/nv3 (EPA Hazard Profiles)
m/yr
m (Proposed Land Ban Rule and
m Supporting Documents (1986))
m
Organic K0c's
Benzene
B(A)P
BEHP
Chlordane
DDT/DDE/DDD
DMN
Lindane
PCB
TCE
Toxaphene
(Kd = Koc * Foc)
74.
5,500,000.
2,000,000,000.
170,000.
5,000,000.
0.04
1,080.
320,000.
198.
960.
Decay Rates (/yr)
As 0
Cd 0
Cu 0
Pb 0
Hg 0
Ni 0
Benzene 0
B(A)P 0
BEHP 0
Chlordane 0
DDT/DDE/DDD 0
DMN 0
Lindane 1.0
PCB 0
TCE 0
Toxaphene 0
-------
Table 3.
Baseline Values for the Saturated Zone
Material Type
Effective Porosity
Ground Water Gradient
Hydraulic Conductivity
Ground Water Velocity
Effective Bulk Density
Eh
Ph
Aquifer Thickness
Aquifer Width
(perpendicular to flow)
Sand
0.1
0.005 m/m
2000 m/yr
100 m/yr
2390 kg/m3
+500 mv
6.0
15 m
1000 m
Kd's (I/kg)
As
Cd
Cu
Pb
Hg
Ni
5
14
41
234
322
12
.86
.9
.9
.
'.2
Benzene
B(A)P
BEHP
Chlordane
DDT/DDE/DDD
DMN
Lindane
PCB
TCE
Toxaphene
0
0
0
0
0
0
0
0
0
0
Decay Rates (/yr)
As
Cd
Cu
Pb
Hg
Ni
Benzene
B(A)P
BEHP
Chlordane
DDT/DDE/DDD
DMN
Lindane
PCB
TCE
Toxaphene
0
0
0
0
0
0
0
0
0
8.43
0.904
607.1
1.0
0
0.904
0
-------
Table 4.
Background Concentrations for Baseline Case (mg/1)
As 0.0004 Benzene 0.
Cd 0.001 B(A)P 0.
Cu 0.01 BEHP 0.
Pb 0.001 Chlordane 0.
Hg 0.0003 DDT/DDE/DDD 0.
Ni 0.0027 DMN 0.
Lindane 0.
PCB 0.
TCE 0.
Toxaphene 0.
-------
Table 5.
Parameters Varied for Sensitivity Runs.
Distance
to Comp- Depth
liance to GW
Point (m) (m) FOC
0. 0.
10. 0.
0.
5. 0.
0.
1. 0.
0.
10. 0.
0.
5. 0.
0.
1. 0.
0.
10. 0.
0.
5. 0.
0.
1. 0.
0.
150. 0. 0.
10.
0.
0001
01
0001
01
0001
01
0001
01
0001
01
0001
01
0001
01
0001
01
0001
01
0001
01
Aquifer
Recharge Thickness
(m/yr) (m)
0
0
0.
0
0
0
0
0
0
0
0
0
0
0
0
.5
.25
00635
.5
.25
.00635
.5
.25
.00635
.5
.25
.00635
.5
.25
.00635
15.
78.6
5.
78.6
5.
78.6
5.
15.
78.6
5.
78.6
5.
78.6
5.
Designation Table
B4-0
S7-0
S8-0
S9-0
S10-0
Sll-0
S12-0
S7-OR1
S8-OR1
S9-OR1
S10-OR1
S11-OR1
S12-OR1
S7-OR2
S8-OR2
S9-OR2
S10-OR2
S11-OR2
S12-OR2
B4-150
S7-150
S7-150R1
S7-150R2
S7-150T1
S7-150T2
S7-150R1T1
S7-150R1T2
S7-150R2T1
S7-150R2T2
S8-150
S8-150R1
S8-150R2
S8-150T1
S8-150T2
S8-150R1T1
S8-150R1T2
S8-150R2T1
S8-150R2T2
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
-------
Table 5, continued.
Parameters Varied for Sensitivity Runs.
Distance
to Comp- Depth Aquifer
"Nance to GW Recharge Thickness
Point (m) (m) FOC (m/yr) (m)
150. 5. 0.0001 0.5
0.25
0.00635
0.5
0.25
0.00635
0.01 0.5
0.25
0.00635
0.5
* 0.25
0.00635
1. 0.0001 0.5
0.25
0.00635
0.5
0.25
0.00635
0.01 0.5
0.25
0.00635
0.5
0.25
0.00635
15.
78.6
5.
78.6
5.
78.6
5.
15.0
78.6
5.
78.6
5.
78.6
5.
15.0
78.6
5.
78.6
5.
78.6
5.
15.0
78.6
5.
78.6
5.
78.6
5.
Designation Table
S9-150
S9-150R1
S9-150R2
S9-150T1
S9-150T2
S9-150R1T1
S9-150R1T2
S9-150R2T1
S9-150R2T2
S10-150
S10-150R1
S10-150R2
S10-150T1
S10-150T2
S10-150R1T1
S10-150R1T2
S10-150R2T1
S10-150R2T2
Sll-150
S11-150R1
S11-150R2
S11-150T1
S11-150T2
S11-150R1T1
S11-150R1T2
S11-150R2T1
S11-150R2T2
S12-150
S12-150R1
S12-150R2
S12-150T1
S12-150T2
S12-150R1T1
S12-150R1T2
S12-150R2T1
S12-150R2T2
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
10
-------
Table 5, continued.A:
Parameters Varied for Sensitivity Runs.
Distance
to Comp-
liance
Point (m)
50.
150.
500.
1000.
50.
150.
500.
1000.
Depth
to GW
(m)
0.
10.
5.
1.
0.
10.
5.
1.
0.
10.
5.
1.
0.
10.
5.
1.
0.
FOC
0.0001
0.01
0.0001
0.01
0.0001
0.01
0.0001
0.01
0.0001
0.01
0.0001
0.01
0.0001
0.01
0.0001
0.01
0.0001
0.01
0.0001
0.01
0.0001
0.01
0.0001
0.01
0.0001
Aquifer
Recharge Thickness
(m/yr) (m)
0.5 15.0
0.25
0.00635
0.25
0.00635
0.25
0.00635
0.25
0.00635
Designation
B4-50
S7-50
S8-50
S9-50
S10-50
Sll-50
S12-50
B4-150
S7-150
S8-150
S9-150
S10-150
Sll-150
S12-150
B4-500
S7-500
S8-500
S9-500
S10-500
Sll-500
S12-500
B4-1000
S7-1000
S8-1000
S9-1000
S10-1QOO
Sll-1000
S12-1000
S13-50
S14-50
S13-150
S14-150
S13-500
S14-500
S13-1000
S14-1000
Table
81
82
83
84
85
86
87
26
27
36
45
54
63
72
88
89
90
91
92
93
94
95
96
97
98
99
100
101
1 102
103
104
105
106
107
108
109
11
-------
Table 5, continued.
Parameters Varied for Sensitivity Runs.
For these sensitivity runs, the depth to the groundwater was 0
meters, FOC was 0.0001, and recharge was 0.5 m/yr. The parameters
altered were groundwater velocity, aquifer thickness, groundwater
eh/ph, and sludge moisture content.
Distance
to Well
(m)
50.
150.
500.
1000.
50.
150.
500.
1000.
50.
150.
500.
1000.
50.
150.
500.
1000.
Aquifer
Thickness
(m)
15.
560.
78.6
5.0
560.
78.6
5.0
560.
78.6
5.0
560.
78.6
5.0
15.0
Velocity
(m/yr)
1000.
10.
1.
1000.
10.
1.
1000.
10.
1.
1000.
10.
1.
100.
eh/ph
mv/su
+500/6.0
+150/6.0
-200/7.0
+150/6.0
-200/7.0
+150/6.0
-200/7.0
+150/6.0
-200/7.0
Moisture
Content Designation
0.80 S15-50
S16-50
S17-50
S15-150
S16-150
S17-150
S15-500
S16-500
S17-500
S15-1000
S16-1000
S17-1000
S18-50
S19-50
S20-50
S18-150
S19-150
S20-150
S18-500
S19-500
S20-500
S18-1000
S19-1000
S20-1000
S21-50
S22-50
S21-150
S22-150
S21-500
S22-500
S21-1000
S22-1000
0.95 S23-50
0.60 S24-50
0.95 S23-150
0.60 S24-150
0.95 S23-500
0.60 S24-500
0.95 S23-1000
0.60 S24-1000
Table
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
12
-------
Table 6.
Health Effects Levels (mg/1).
Chemical 10'6 1CT5 10'4
0.05
0.010
1.3
0.05
0.002
1.75
0.005
0.000003
0.00248
0.000021
0.000102
0.000001
0.004
0.00000454
0.005
0.005
0.05
0.010
1.3
0.05
0.002
1.75
0.005
0.00003
0.0248
0.00021
0.00102
0.00001
0.004
0.0000454
0.005
0.005
0.05
0.010
1.3
0.05
0.002
1.75
0.005
0.0003
0.248
0.0021
0.0102
0.0001
0.004
0.000454
0.005
0.005
As
Cd
Cu
Pb
Hg
Ni
Benzene
B(A)P
BEHP
Chlordane
DDT/DDE/DDD
DMN
Lindane
PCB
TCE
Toxaphene
Note: The health effects levels vary for only 6 of the organics:
Benzo(a)pyrene, Bis(2-ethylhexyl)pthalate, Chlordane, DDT/DDE/DDD,
Dimethylnitrosamine, and PCB's. All other chemicals have a single
health effects level.
13
-------
Table 7.
Base Case, Depth to Groundwater 0 Meters,
Distance to Wells 0 Meters.
84 0 -- Base Case.
CHEMICAL
SAT CONC VAPOR C BCKGRND
SUM
HEL
CS
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
3.83E-12
6.82E-04
2.47E-06
1.10E-05
2.70E-06
O.OOE+00
4.50E-05
O.OOE+00
O.OOE+00
4.00E-04
l.OOE-03
l.OOE-02
l.OOE-03
3.00E-04
2.70E-03
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
5.04E-02
l.OOE-02
1.13E+00
5.24E-02
1.95E-03
1.75E+00
5.00E-03
3.00E-04
2.45E-01
2.09E-03
1.02E-02
l.OOE-04
4.00E-03
4.54E-04
5.00E-03
5.00E-03
5.00E-02
l.OOE-02
1.30E+00
5.00E-02
2.00E-03
1.75E+00
5.00E-03
3.00E-04
2.45E-01
2.10E-03
1.02E-02
l.OOE-04
4.00E-03
4.54E-04
5.00E-03
5.00E-03
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
14
-------
Table 8.
The Effects of Increasing Depth of Unsaturated
Zone from 0 to 10 feet.
S7-0, D to GW=10M, DIST=OM, FOC=10-4, R=0.5M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
5.64E+00
1.14E+00
1.51E+03
1.71E+02
4.73E+00
1.99E+02
2.75E-01
9.67E+01
1.62E+03
1.80E+02
4.08E+01
1.89E-03
6.16E+01
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
2720.0 %
3066.7 %
17876.2 %
49322.0 %
67471.4 %
2759.2 %
0.0 %
-0.1 %
35980.2 %
0.0 %
4212.9 %
0.0 %
2625.7 %
4.6 %
0.0 %
0.0 %
As: Travel time in the unsaturated zone allows dispersion,
reducing concentration at saturated zone, allowing higher sludge
concentrations.
Cd: Same as for As.
Cu: Higher Kd than for As or Cd (41.9 vs 5.86 and 14.9) retains Cu
in unsaturated zone for longer period of time, allowing greater disper-
sion, lower concentrations, and higher allowable sludge concentrations.
Pb: Same as for Cu. Travel time of 1870 years compared to pulse
time of 21 years allows significant dispersion of contaminant plume,
allowing much higher sludge concentrations than base case, and also
higher concentrations relative to base case than As or Cd.
Hg: Same as Cu and Pb. High Kd of 322 produces unsaturated zone
travel time of 2570 years on a pulse of 8.4 years. Significant unsat-
urated zone dispersion of a narrow plume results.
Ni: Same as for As and Cd. Kd of Ni is 12.2 compared with 5.86
and 14.9 for As and Cd. Travel time of 144 years on a pulse of 72
years yields significant dispersion, but not as much as for Cu, Pb, and
Hg.
Benzene: Pulse time is 68 years but travel time is only 14 years,
so dispersion in the unsaturated zone has insufficient time to reduce
peak.
B(A)P: Same as Benzene, release time is 397,000 years while the
unsaturated zone travel time is only 31,500 years.
15
-------
BEHP: Very long travel time, 1,800,000 years, short release time,
22.6 years, yields high dispersion and high allowable sludge
concentrations. Vapor pathway controls for BEHP, but not until sludge
concentration reaches about 100 mg/kg.
Chlordane: Release time 100,000 years, travel time 2,700 years.
Contaminant keeps leaching and eventually overcomes effects of
dispersion in unsaturated zone. Peak takes longer to reach the
saturated zone, but is the same as for the base case with no
unsaturated zone.
DDT: Vapor contributing but not controlling (0.00047 mg/1 vapor vs
0.0097 mg/1 aquifer). Travel time for peak through the unsaturated
zone is 4,600 years, release time 114 years. Time spent in unsaturated
zone is sufficient to reduce peak concentration allowing higher sludge
concentrations.
DMN: Release time is 24 years, peak travel time is 14.6 years.
The peak traverses the unsaturated zone before the source is depleted
so the peak is not reduced.
Lindane: Travel time of 7.4 years allows significant degradation
in the unsaturated zone.
PCB: The release time of 2,000,000 years is significantly greater
than the travel time of 50,000 years, so the 4.6% increase indicated
over the base case is probably not significant. Allowable sludge dry
weight concentrations are probably equivalent in both cases.
TCE: Release time is 1000 years, travel time only 25 years, so the
peak traverses the unsaturated zone before the source is depleted, so
the peak is not reduced.
Toxaphene: Same as for TCE, release time is 89 years, travel time
only 19 years, dispersion affects peak travel time to saturated zone
but not peak concentration.
16
-------
Table 9.
The Effects of Increased Depth to Groundwater
and a Higher Organic Content in the Soil.
S8-0, D to GW=10M, DIST=OM, FOC=10-2, R=0.5M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
5.65E+00
1.14E+00
1.54E+03
4.73E+00
2.00E+02
2.75E-01
1.58E+02
1.63E+03
1.80E+02
7.31E+02
1.89E-03
l.OOE+05
6.59E+02
4.06E+00
5.10E-01
% DIFFERENCE
2725.0 %
3066.7 %
18233.3 %
67471.4 %
2773.6 %
0.0 %
63.2 %
36202.9 %
0.0 %
77172.7 %
0.0 %
4424679.0 %
4.6 %
0.0 %
41.7 %
As, Cd, Cu, Hg, and Ni are the same as for the S7-0, Table 8, case
above. Slight differences are due to stopping the convergence at
slightly different places. The difference between this case, S8-0, and
S7-0 (Table 8) above is that the organic FOC has been increased to 0.01
instead of 0.0001. This should increase the peak retardation,
increasing the peak travel time, and tending to allow higher sludge dry
weight concentrations.
Benzene: Travel time has been increased to 48 years, but is still
less than the release time of 68 years. Therefore, the peak
concentration, and therefore the allowable dry weight concentration, is
the same as the base case.
B(A)P: Release time is still the same as for the S7-0 case above,
397,000 years, but the travel time has now been increased to 725,000
years allowing dispersion to reduce the peak and allowing somewhat
higher sludge concentrations.
BEHP: BEHP is vapor controlled at the dry weight concentration of
1600 mg/kg, so although the unsaturated zone travel time has been
increased by the increase in retardation, the total peak concentration
has not been significantly changed from the previous case. Allowable
dry weight concentrations of BEHP are still about 360 times those of
the base case.
Chlordane: Travel time has been increased to 78,000 years, but is
still less than the release time of 105,000 years, so allowable dry
weight concentrations of Chlordane are unchanged from the base case.
17
-------
DDT: The increase in travel time to 400,000 years allows
dispersion to significantly reduce the peak concentration from the base
case, allowing higher sludge concentrations. The vapor pathway is
becoming dominant, providing .0085 mg/1 of the .0102 mg/1 health
effects level, the groundwater pathway providing the remaining .0017
mg/1.
DMN: The very low Koc of 0.04 for DMN provides very little
velocity retardation in the unsaturated zone, so raising the FOC from
.0001 to .01 only raises the Kd from .000004 to .0004. This has
essentially no effect on the travel time of 14.6 years, so the release
time of 23.9 years still controls and the peak concentration is not
reduced.
Lindane: The increase in FOC increases the travel time of Lindane
from 7.4 years for case S7-0 to 25.6 years for this case allowing
essentially total degradation assuming a decay constant of 1. This
allows essentially a limitless inventory of Lindane in the landfill.
PCB: Although the travel time has been increased from 50,000 years
to 160,000 years, the release time of nearly 2,000,000 years still
dominates, so peak outflow concentrations are unchanged and allowable
dry weight concentrations are unchanged.
TCE: Travel time is increased from 25 years to 110 years, but is
still below the release time of 1000 years, so allowable dry weight
concentrations are unchanged.
Toxaphene: The travel time has been increased to 135 years
compared with the release time of 89 years, so dispersion is beginning
to reduce the peak concentration entering the saturated zone, allowing
for 42% higher dry weight concentrations in the sludge.
18
-------
Table 10.
The Effects of Increasing Depth to
Groundwater from 0 to 5 meters.
S9-0, D=5M, DIST=OM, FOC=10-4, R=0.5M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
2.89E+00
5.70E-01
6.00E+02
8.51E+01
2.36E+00
9.98E+01
2.75E-01
9.67E+01
1.62E+03
1.80E+02
2.09E+01
1.89E-03
1.44E+01
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
1345.0 %
1483.3 %
7042.9 %
24495.4 %
33614.3 %
1333.9 %
0.0 %
-0.1 %
35980.2 %
0.0 %
2109.3 %
0.0 %
537.2 %
4.6 %
0.0 %
0.0 %
For this case, the depth to groundwater has been reduced from 10
meters for the previous S7-0 (Table 8) case to 5 meters. One would
expect generally lower allowable sludge dry weight concentrations than
for that case, but still, for most chemicals, higher concentrations
than for the base case. This is exactly what is found. Except for
BEHP and Lindane, all chemicals having higher allowable dry weight
concentrations than the base case have allowable sludge concentrations
for this case about 1/2 those for the S7-0 (Table 8) case, but still
substantially higher than the base case. The allowable sludge
concentration for BEHP is the same for both S7-0 and S9-0 cases because
BEHP is vapor controlled at this sludge concentration, the vapor
concentration being the dominant constituent of the total
concentration. The allowable sludge concentration of Lindane is only
about 1/4 that of the S7-0 case because the reduced travel time
increases the outflow concentration exponentially.
19
-------
Table 11.
The Effects of Increasing Depth to Groundwater from 0 to 5 meters
and Increasing Soil Organic Content from 0.0001 to 0.01.
S10-0, GW 5M, FOC 0.01, DIST OM, R 0.5 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9..00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
2.74E+00
5.72E-01
6.61E+02
8.53E+01
2.36E+00
9.98E+01
2.75E-01
1.08E+02
1.62E+03
1.80E+02
6.24E+02
1.89E-03
l.OOE+05
6.59E+02
4.06E+00
3.81E-01
% DIFFERENCE
1270.0 %
1488.9 %
7769.0 %
24553.2 %
33614.3 %
1333.9 %
0.0 %
11.6 %
35980.2 %
0.0 %
65862.0 %
0.0 %
4424679.0 %
4.6 %
0.0 %
5.8 %
This case is the same as the S9-0 case (Table 10) except the FOC
has been increased from 0.0001 to 0.01 increasing retardation in the
unsaturated zone. This allows greater dispersion of the chemical plume
reducing the outflow concentration and allowing higher sludge
concentrations. One would expect, then, generally higher allowable
sludge concentrations for this case than for the S9-0 case (Table 10).
This only applies to the organics, however, so one should see no change
in the allowable metal concentrations.
This is what is found in the results. For the organics with un-
changed allowable sludge concentrations, the increase in travel times
have been insufficient to exceed release times, so peak outflow
concentrations are still at leachate levels. The allowable dry weight
concentration of BEHP is unchanged from the S9-0 case (Table 10)
because it is still vapor controlled. For B(A)P and Toxaphene,
allowable sludge concentrations are increased over the S9-0 and base
cases because the travel times have been increased to exceed the
release times. For DDT the travel time has been substantially
increased over the release time compared to the S9-0 case resulting in
significantly higher allowable sludge concentrations than for that case
or the base case. The increase in travel time for Lindane has
increased its allowable sludge concentration almost without bounds due
to its relatively high decay rate of 1.
20
-------
Table 12.
The Effects of Increasing Depth to Groundwater from 0 to 1 meter.
Sll-0, GW 1M, DIST OM, FOC 0.0001, R 0.5 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
5.64E-01
1.14E-01
1.52E+02
1.74E+01
4.73E-01
2.00E+01
2.75E-01
9.67E+01
1.57E+03
1.80E+02
4.28E+00
1.89E-03
3.44E+00
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
182.0 %
216.7 %
1709.5 %
4928.9 %
6657.1 %
187.4 %
0.0 %
-0.1 %
34866.6 %
0.0 %
352.4 %
0.0 %
52.2 %
4.6 %
0.0 %
0.0 %
This is the same case as S9-0 (Table 10) except the depth to
groundwater has been reduced by a factor of 5 from 5 meters to 1 meter.
We see lower allowable dry weight concentrations because there is less
dispersion in the unsaturated zone due to shorter travel times there.
All chemicals in the S9-0 case (Table 10) having unchanged allowable
sludge concentrations from the base case still have unchanged
concentrations in this case. All chemicals allowing higher sludge
concentrations than the base case in case S9-0 still allow higher
concentrations in this case, but at levels reduced by factors of from 4
to 7. The only exceptions are BEHP, which is unchanged from the S9-0
case because it is still vapor controlled due in part to its very high
Koc of 2X10^, and Lindane, which is reduced by a factor of 10 from the
S9-0 case due to the exponential effects of decay. Since Lindane's
travel time is reduced from 5.6 to 1.8 years, the effects of
degradation are exponentially reduced.
21
-------
Table 13.
The Effects of Increasing Depth to Groundwater from 0 to 1 meter
and Increasing Organic Soil Content from 0.0001 to 0.01.
S12-0, GW 1M, FOC 0.01, DIST OM, R 0.5 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
5.65E-01
1.14E-01
1.54E+02
1.71E+01
4.73E-01
2.00E+01
2.75E-01
9.68E+01
1.63E+03
1.80E+02
2.88E+02
1.89E-03
3.40E+03
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
182.5 %
216.7 %
1733.3 %
4842.2 %
6657.1 %
187.4 %
0.0 %
0.0 %
36202.9 %
0.0 %
30344.0 %
0.0 %
150342.5 %
4.6 %
0.0 %
0.0 %
This case and Sll-0 (Table 12) are the same except the FOC has
been increased from .0001 to .01 for the organics. This increases the
peak travel time for retarded chemicals allowing greater dispersion and
allowing generally greater sludge concentrations. The metals are
unchanged because their Kd's are unaffected. Of the organics in the
Sll-0 case (Table 12), only three have allowable sludge concentrations
significantly exceeding those of the base case. The rest are unchanged
from the base case in both the Sll-0 and S12-0 cases (Tables 12 and 13,
respectively) because the travel times are still less than the release
times allowing the peak concentration to overpower the effects of
dispersion in the unsaturated zone. Of the three organics showing
increased allowable dry weight concentrations over the base case, two
of them, DDT and Lindane, show significantly increased allowable sludge
concentrations in the S12-0 case compared with the Sll-0 case because
the travel times allow greater dispersion in the case of DDT, and
greater dispersion and degradation in the case of Lindane. BEHP shows
the same increased allowable sludge concentrations in both the Sll-0
and S12-0 cases because it is vapor controlled due to the very high
unsaturated zone travel time of 2X10' years caused by the very high Koc
of 2X109.
22
-------
Table 14.
The Effects of Increasing the Depth to Groundwater from 0 to 10
Meters, and Decreasing Recharge from 0.5 m/y to 0.25 m/y.
S7-OR1, D to GW=10M, DIST=OM, FOC=10-4, R=0.25M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
3.43E+00
1.07E+00
1.39E+03
1.60E+02
4.44E+00
1.87E+02
2.75E-01
9.69E+01
1.62E+03
1.80E+02
3.85E+01
1.89E-03
4.90E+02
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
1615.0 %
2872.2 %
16477.6 %
46142.0 %
63328.4 %
2586.2 %
0.0 %
-0.1 %
35980.2 %
0.0 %
3969.9 %
0.0 %
21581.4 %
4.6 %
0.0 %
0.0 %
The chemicals which have no change from the base case have travel
times shorter than their release times. Dispersion in the unsaturated
zone therefore has insufficient time to reduce the leachate
concentration. The 4.6% increase in PCB concentrations over the base
case is judged insignificant. The other chemicals, with significantly
greater allowable sludge concentrations than the base case, all have
travel times exceeding their release times, allowing dispersion to
reduce leachate concentrations in the unsaturated zone. The higher the
ratio of travel time to release time, the higher the allowable sludge
concentration in the landfill. Therefore, the chemicals with higher
Kd's tend to have the higher allowable sludge concentrations compared
with their base case values. BEHP has a very high Kd of 200,000 for
this case, but is vapor controlled at high sludge concentrations, so
its allowable concentration is about equal to those of lead and mercury
with Kd's of 234 and 322. Lindane has a relatively small Kd of 0.108,
but the travel time of 9.2 years in the unsaturated zone allows about a
9000 fold decrease in concentration due to degradation, so the
allowable sludge concentrations are increased markedly.
For most of the chemicals, there is a slight decrease in allowable
sludge dry weight concentrations as compared to the S7-0 case (Table 8)
with 0.5 m/y recharge. The reason for the change is that when the
recharge is halved from 0.5 m/y to 0.25 m/y, the release time is
doubled given the same inventory, but the travel time is not quite
23
-------
doubled. The relation SLUDGEMAN uses for calculating travel time for
water in the unsaturated zone is
travel time = d*t*(R/K)**(l/(2b+3)/R
where d = depth to groundwater (m)
t = unsaturated zone porosity
R = recharge rate (m/y)
K = saturated hydraulic conductivity
for the unsaturated zone material
b = "b" value, or slope of the log-log plot of matrix potential
versus moisture content.
So, for this case,
travel time = 10*0.39*(0.25/10000)**(l/2*4+3)/0.25 = 5.95 years
compared with 3.17 years for the 0.5 m/y recharge case. Thus, halving
the recharge does not quite double the travel time.
If the release time were doubled and the travel time doubled, the
plume dynamics would remain constant relative to the effects of
dispersion as simulated in SLUDGEMAN, and the outflow concentration at
the saturated zone would remain constant. However, since the travel
time is not quite doubled, dispersion has a little less time to reduce
the peak concentration in the plume, and the outflow concentration is
raised. This requires a slightly lower sludge concentration in order to
reduce the release time and keep the ratio of travel time to release
time constant.
Two chemicals whose allowable sludge concentrations are not
reduced relative to the S7-0 case (Table 8) with 0.5 m/y recharge, are
BEHP and Lindane. BEHP is vapor controlled at a dry weight
concentration of 1600 mg/kg, so the unsaturated zone dynamics have
little effect. The increase in travel time due to halving the recharge
allows much greater degradation of Lindane, allowing an 8-fold increase
in sludge dry weight concentration.
24
-------
Table 15.
The Combined Effects of Increased Depth to Groundwater,
Increased Soil Organic Content, and Reduced Recharge.
S8-OR1, D to GW=10M, DIST=OM, FOC=10-2, R=0.25M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
3.43E+00
1.07E+00
1.39E+03
1.60E+02
4.44E+00
1.87E+02
2.75E-01
1.51E+02
1.63E+03
1.80E+02
7.22E+02
1.89E-03
l.OOE+05
6.59E+02
4.06E+00
4.91E-01
% DIFFERENCE
1615.0 %
2872.2 %
16477.6 %
46142.0 %
63328.4 %
2586.2 %
0.0 %
56.0 %
36202.9 %
0.0 %
76221.7 %
0.0 %
4424679.0 %
4.6 %
0.0 %
36.4 %
This case is nearly identical to the S8-0 case (Table 9) with 0.5
m/y recharge. The comments describing the results for the S7-OR1 case
(Table 14) above apply here. The 0.25 m/y recharge doubles the release
time given the same inventory and leachate concentration, but the
travel time does not quite double, so most of the chemicals with higher
allowable concentrations than the base case have slightly lower
allowable concentrations at 0.25 m/y than at 0.5 m/y recharge. The
exceptions are BEHP which is vapor controlled at these sludge
concentrations, and Lindane, which degrades significantly more with the
increased travel time.
25
-------
Table 16.
The Effects of Increasing Depth to Groundwater from 0 to 5 Meters
and Reducing Recharge from 0.5 m/y to 0.25 m/y.
S9-OR1, D=5M, DIST=OM, FOC=10-4, R=0.25M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
1.70E+00
5.37E-01
7.05E+02
8.02E+01
2.22E+00
9.33E+01
2.75E-01
9.67E+01
1.62E+03
1.80E+02
1.96E+01
1.89E-03
5.23E+01
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
750.0 %
1391.7 %
8292.9 %
23079.4 %
31614.3 %
1240.5 %
0.0 %
-0.1 %
35980.2 %
0.0 %
1971.9 %
0.0 %
2214.2 %
4.6 %
0.0 %
0.0 %
This is the same situation as for the S7-OR1 and S8-OR1 cases
above (Tables 14 and 15, respectively). Those chemicals not changed
from the base case have travel times less than their release times, so
that the outflow concentration into the saturated zone comes to
equilibrium at the leachate concentration. Chemicals with allowable
sludge concentrations above the base case are generally little changed
from the S9-0 case (Table 10) with 0.5 m/y recharge because the
decrease in recharge increases the release time but also increases the
travel time by nearly the same amount. So, the plume dynamics with
regard to dispersion remain nearly constant. Travel times for the peak
concentrations are nearly doubled, but the peaks are at the same
concentrations as for the 0.5 m/y recharge case. Lindane's allowable
sludge concentration is about 4 times higher than that for the 0.5 m/y
recharge case due to greater degradation during the longer travel time.
26
-------
Table 17.
The Combined Effects of Increasing Depth to Groundwater from 0 to 5
Meters, Increasing Soil Organic Content from 0.0001 to 0.01,
and Reducing Recharge from 0.5 m/y to 0.25 m/y.
S10-OR1, D=5M, DIST=OM, FOC=10-2, R=0.25M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
1.70E+00
5.37E-01
7.05E+02
8.02E+01
2.22E+00
9.33E+01
2.75E-01
1.06E+02
1.63E+03
1.80E+02
6.12E+02
1.89E-03
l.OOE+05
6.59E+02
4.06E+00
3.75E-01
% DIFFERENCE
750.0 %
1391.7 %
8292.9 %
23079.4 %
31614.3 %
1240.5 %
0.0 %
9.5 %
36202.2 %
0.0 %
64593.4 %
0.0 %
4424579.0 %
4.6 %
0.0 %
4.2 %
The S10 case is the same as the S9 case except that the Foe's for
the organics have been increased from 0.0001 to 0.01. So, the results
for the metals remain unchanged. Allowable dry weight concentrations
of B(A)P and Toxaphene have slipped above the 0 level due to their
travel times edging just above their release times. Otherwise, the
chemicals with unchanged allowable dry weight concentrations compared
to the base case are still unchanged. BEHP is still essentially
unchanged from the S9-OR1 case (Table 16) because its vapor
concentration is still its dominant influence at this sludge
concentration. DDT shows a marked increase in its allowable sludge
concentration due to the 100-fold increase in its travel time allowing
dispersion to significantly reduce its peak concentration. Increasing
Lindane's Kd from .108 to 10.8 has increased its travel time to the
point where degradation is so great that even with a sludge
concentration of 100,000 mg/kg, we only see an outflow concentration of
lO'll mg/1. So, Lindane's allowable sludge concentration has been
greatly increased by the increased retardation in the unsaturated zone.
27
-------
Table 18.
The Effects of Increasing Depth to Groundwater from 0 to 1 Meter
while Reducing Recharge from 0.5 m/y to 0.25 m/y.
S11-OR1, GW 1M, DIST OM, FOC 0.0001, R 0.25 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
5.29E-01
1.07E-01
1.48E+02
1.60E+01
4.44E-01
1.87E+01
2.75E-01
9.67E+01
1.57E+03
1.80E+02
4.03E+00
1.89E-03
4.86E+00
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
164.5 %
197.2 %
1661.9 %
4524.3 %
6242.9 %
168.7 %
0.0 %
-0.1 %
34866.6 %
0.0 %
326.0 %
0.0 %
115.0 %
4.6 %
0.0 %
0.0 %
This is really the same case as the S7-OR1 case above (Table 14),
but with all allowable dry weight concentrations scaled down by a
factor of 10 due to the depth to groundwater being one-tenth that in
the earlier case (1 m vs 10 m). Cadmium's allowable dry weight
concentration, for example, is 197% greater than for the base case, or
2.97 times greater (.107 mg/kg vs .0036 mg/kg). In the S7-OR1 case
(Table 14), cadmium's allowable was 2872% higher or 29.72 times
greater. Some chemicals vary from this 10 to 1 rule somewhat, but not
by amounts that are numerically significant. For example, copper has
an allowable for this case of 148 mg/kg compared to 1390 for the S7-OR1
case. This is a ratio of .1065.
The biggest difference is seen in the results for arsenic. In
this case, the allowable is .529 and for the S7-OR1 case it is 3.43
mg/kg, a ratio of 0.154. But arsenic is an especially difficult
chemical for which to estimate allowable dry weight concentrations.
This is due to difficulties encountered when interpolating the MINTEQ
data to simulate the effects of sorption in the saturated zone due to
the eh/ph there. One difficulty is trying to obtain a concentration in
the saturated zone equal to the health effects level of 0.05 mg/1 for
arsenic by finding a value between 0.06 mg/1 and 1.27 mg/1 that yields
0.05 mg/1 when interpolated between 0.00024 mg/1 and 1.06 mg/1
respectively. A value of 0.12 is about right, but when SLUDGEMAN
attacks the problem with, say, 0.06 and obtains a result of 0.00024, it
tries increasing the dry weight concentration by about 100, to get
28
-------
closer to the 0.05 it wants. This produces a concentration entering
the saturated zone of about 6, which after sorption results in about
5.3. Then SLUDGEMAN reduces this by about 100 to try to achieve 0.05
and gets back to the 0.06 with which it started. Thus SLUDGEMAN can
oscillate between two values.
At this point, the user can edit a dry weight concentration into
the SLUDGIN.OUT file that lies between the extremes SLUDGEMAN has been
attempting. We have found this to help on occasion, but not always.
Often SLUDGEMAN goes back to bouncing between the limits it previously
chose. Presumably in such cases, slight variations in input produce
widely varying results, due to the interpolation, and one chooses the
lower sludge concentration to be conservative. In the cases in which
SLUDGEMAN has oscillated like this, however, we have not seen the
oscillations over a greater range than 3 to 1. So, in our experience,
the oscillations have been much less than the 100 to 1 range depicted
in the example above.
As mentioned, most of the S11-OR1 results (Table 18) are just
about 10% of those for the S7-OR1 case (Table 14). Two notable
exceptions are BEHP and Lindane. As in the previous examples, the
reasons are that BEHP is still vapor controlled at these sludge
concentrations although the groundwater concentration is becoming more
important with the shallower groundwater, and Lindane degrades much
less due to the shorter travel time in the shorter 1 meter unsaturated
zone.
29
-------
Table 19.
The Combined Effects of Increasing Depth to Groundwater from 0 to 1
Meter, Increasing Soil Organic Content from 0.0001 to 0.01, and
Reducing Recharge from 0.5 m/y to 0.25 m/y.
S12-OR1, GW 1M, DIST OM, FOC 0.01, R 0.25 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
5.29E-01
1.07E-01
1.48E+02
1.60E+01
4.44E-01
1.87E+01
2.75E-01
9.67E+01
1.63E+03
1.80E+02
2.76E+02
1.89E-03
l.OOE+05
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
164.5 %
197.2 %
1661.9 %
4524.3 %
6242.9 %
168.7 %
0.0 %
-0.1 %
36202.9 %
0.0 %
29075.5 %
0.0 %
4424579.0 %
4.6 %
0.0 %
0.0 %
The explanation of these results is the same as for the S10-OR1
and S8-OR1 cases (Tables 17 and 15, respectively). The metal
concentrations are unchanged because the increase in Foe has not
affected them. Organics unchanged from the base case are still
unchanged because their travel times are still less than their release
times. BEHP is unchanged from the S11-OR1 case (Table 18) because it
is vapor controlled and retardation in the unsaturated zone has little
effect. The allowable sludge concentration of DDT is increased because
the increase in Kd has increased the travel time substantially (from
900 years to 75,000 years) allowing dispersion to reduce the peak
concentration and allowing greater sludge input concentrations. The
allowable sludge concentration of Lindane is increased because the
increase in retardation has increased its travel time from 3.05 years
for the S11-OR1 case to 10.2 years for this case resulting in
substantially greater degradation and more dispersion.
30
-------
Table 20.
The Effects of Increasing Depth to Groundwater from 0 to 10 Meters
while Significantly Reducing Recharge from 0.5 to 0.00635 m/y.
S7-OR2, D to GW=10M, DIST=OM,, FOC=10-4, R=0.00635M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
3.06E+00
7.69E-01
1.06E+03
1.15E+02
3.18E+00
1.34E+02
2.75E-01
9.68E+01
1.62E+03
1.80E+02
2.78E+01
1.89E-03
l.OOE+05
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
1430.0 %
2036.1 %
12519.0 %
33137.0 %
45328.4 %
1825.2 %
0.0 %
0.0 %
35980.9 %
0.0 %
2838.7 %
0.0 %
4424679.0 %
4.6 %
0.0 %
0.0 %
TKese results are nearly identical with as those for the S7-OR1
case (Table 14), so the comments for that case apply here. The
unchanged values have release times exceeding travel times so
dispersion is ineffective in reducing peak concentrations. Dispersion
only increases travel time for the peak. For those values changed from
the base case, their travel times exceed their release times, allowing
dispersion to reduce their outflow concentrations and allowing higher
sludge concentrations in the landfill. BEHP is vapor controlled at
this concentration, so groundwater changes have little effect on
allowable concentrations. The lower recharge of 0.00635 m/y for this
case compared with 0.25 m/y for the S7-OR1 case causes a greater travel
time through the unsaturated zone for all the chemicals. This
significantly increases the allowable dry weight concentrations for
Lindane due to its decay rate of 1. The other chemicals, with
allowable sludge concentrations greater than those of the base case,
have somewhat lower allowable dry weight concentrations in this case
than in the S7-OR1 and S7-0 cases (Tables 14 and 8, respectively)
because the travel times are not increased proportionally to the
decrease in recharge rate. Therefore, the greater effects of disper-
sion do not cancel the effects of longer release time, necessitating a
reduction in release time and therefore lower sludge concentration.
This is more fully explained in the comments concerning the S7-OR1 case
above (Table 14).
31
-------
Table 21.
The Combined Effects of Increasing Depth to Groundwater from 0 to 10
Meters, Increasing Soil Organic Content from 0.0001 to 0.01, and
Reducing Recharge significantly from 0.5 m/y to 0.00635 m/y.
S8-OR2, D to GW=10M, DIST=OM, FOC=10-2, R=0.00635M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
3.07E+00
7.69E-01
1.06E+03
1.15E+02
3.18E+00
1.34E+02
2.75E-01
1.23E+02
1.63E+03
1.80E+02
6.74E+02
1.89E-03
l.OOE+05
6.59E+02
4.06E+00
4.13E-01
% DIFFERENCE
1435.0 %
2036.1 %
12519.0 %
33137.0 %
45328.4 %
1825.3 %
0.0 %
27.1 %
36202.9 %
0.0 %
71147.4 %
0.0 %
4424679.0 %
4.6 %
0.0 %
14.7 %
The results for this case are nearly identical to those of the
S8-OR1 and S8-0 cases discussed above (Tables 15 and 9, respectively).
Retardation in the unsaturated zone allows dispersion to reduce the
peak concentrations for most of the chemicals. This is true for those
with allowable sludge concentrations exceeding their base case values.
For the unchanged chemicals, their unsaturated zone travel times do not
exceed their release times, so dispersion has insufficient room and
time to reduce their peak concentrations. The peak concentrations for
such chemicals enter the saturated zone at a later time than in the S8-
OR1, S8-0, and base cases, but the peak concentrations are the same.
BEHP is vapor controlled at this concentration, so its allowable sludge
dry weight concentration remains unchanged from the S8-0 and S8-OR1
cases (Tables 9 and 15, respectively). The allowable dry weight
concentration for Lindane is set at a ceiling value of 105 mg/kg due to
the tremendous degradation occurring over its increased travel time for
this case.
32
-------
Table 22.
The Effects of Increasing Depth to Groundwater from 0 to 5 Meters
while Significantly Reducing Recharge from 0.5 to 0.00635 m/y.
S9-OR2, D=5M, DIST=OM, FOC=10-4, R=0.00635M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
1.49E+00
3.84E-01
4.99E+02
5.74E+01
1.59E+00
6.68E+01
2.75E-01
9.67E+01
1.61E+03
1.80E+02
1.41E+01
1.89E-03
l.OOE+05
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
645.0 %
966.7 %
5840.5 %
16489.4 %
22614.3 %
859.8 %
0.0 %
-0.1 %
35757.5 %
0.0 %
1390.4 %
0.0 %
4424679.0 %
4.6 %
0.0 %
0.0 %
The results for this case are nearly identical to those of the
S9-OR1 and S9-0 cases discussed above (Tables 16 and 10, respectively).
Retardation in the unsaturated zone allows dispersion to reduce the
peak concentrations for most of the chemicals. This is true for those
with allowable sludge concentrations exceeding their base case values.
For the unchanged chemicals, their unsaturated zone travel times do not
exceed their release times, so dispersion has insufficient room and
time to reduce their peak concentrations. The peak concentrations for
such chemicals enter the saturated zone at a later time than in the S9-
OR1, S9-0, and base cases, but the peak concentrations are the same.
BEHP is vapor controlled at this concentration, so its allowable sludge
dry weight concentration remains unchanged from the S9-0 and S9-OR1
cases (Tables 10 and 16, respectively).
The allowable dry weight concentration for Lindane is set at a
ceiling value of 105 mg/kg due to the tremendous degradation occurring
over its increased travel time for this case. Lindane's degradation is
much higher for this case than for the S9-OR1 and S9-0 cases because
the decreased recharge has significantly increased the travel time
through the unsaturated zone allowing much greater degradation.
33
-------
Table 23.
The Combined Effects of Increasing Depth to Groundwater from 0 to 5
Meters, Increasing Soil Organic Content from 0.0001 to 0.01, and
Reducing Recharge significantly from 0.5 m/y to 0.00635 m/y.
S10-OR2, D=5M, DIST=OM, FOC=10-2, R=0.00635M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
J.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
1.37E+00
3.84E-01
4.99E+02
5.74E+01
1.59E+00
6.68E+01
2.75E-01
9.92E+01
1.63E+03
1.80E+02
5.46E+02
1.89E-03
l.OOE+05
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
585.0 %
966.7 %
5840.5 %
16489.4 %
22614.3 %
859.8 %
0.0 %
2.5 %
36202.2 %
0.0 %
57616.4 %
0.0 %
4424679.0 %
4.6 %
0.0 %
0.0 %
These results are nearly identical with as those for the S10-OR1
case (Table 17), so the comments for that case apply here. The
unchanged values have release times exceeding travel times so
dispersion is ineffective in reducing peak concentrations. Dispersion
only increases travel time for the peak. For those values changed from
the base case, their travel times exceed their release times, allowing
dispersion to reduce their outflow concentrations and allowing higher
sludge concentrations in the landfill. BEHP is vapor controlled at
this concentration, so groundwater changes have little effect on
allowable concentrations. The lower recharge of 0.00635 m/y for this
case compared with 0.25 m/y for the S10-OR1 case causes a greater
travel time through the unsaturated zone for all the chemicals. This
significantly increases the allowable dry weight concentrations for
Lindane due to its decay rate of 1. The other chemicals, with
allowable sludge concentrations greater than those of the base case,
have somewhat lower allowable dry weight concentrations in this case
than in the S10-OR1 and S10-0 cases (Tables 17 and 11, respectively)
because the travel times are not increased proportionally to the
decrease in recharge rate. Therefore, the greater effects of disper-
sion do not cancel the longer release time, necessitating a shorter
release time and therefore lower sludge concentration. This is more
fully explained in the comments for the S7-OR1 case above (Table 14).
34
-------
Table 24.
The Effects of Increasing Depth to Groundwater from 0 to 1 Meter
while Significantly Reducing Recharge from 0.5 to 0.00635 m/y.
S11-OR2, D=1M, DIST=OM, FOC=10-4, R=0.00635M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
3.16E-01
7.68E-02
1.05E+02
1.15E+01
3.18E-01
1.34E+01
2.75E-01
9.67E+01
1.54E+03
1.80E+02
2.97E+00
1.89E-03
l.OOE+05
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
58.0 %
113.3 %
1150.0 %
3223.7 %
4442.9 %
92.5 %
0.0 %
-0.1 %
34198.2 %
0.0 %
214.0 %
0.0 %
4424679.0 %
4.6 %
0.0 %
0.0 %
These results are nearly identical with those for the S11-OR1 case
(Table 18), so the comments for that case apply here. The unchanged
values have release times exceeding travel times so dispersion is
ineffective in reducing peak concentrations. Dispersion only increases
travel time for the peak. For those values changed from the base case,
their travel times exceed their release times, allowing dispersion to
reduce their outflow concentrations and allowing higher sludge
concentrations in the landfill. BEHP is vapor controlled at this
so groundwater changes have little effect on allowable
The lower recharge of 0.00635 m/y for this case
0.25 m/y for the S11-OR1 case causes a greater travel
the unsaturated zone for all the chemicals. This
increases the allowable dry weight concentrations for
its decay rate of 1. The other chemicals, with
concentrations greater than those of the base case,
concentration,
concentrations,
compared with
time through
significantly
Lindane due to
allowable sludge
have somewhat lower
than in the S11-OR1
because the travel
decrease in recharge
sion do not cancel
allowable dry weight concentrations in this case
and Sll-0 cases (Tables 18 and 12, respectively)
times are not increased proportionally to the
rate. Therefore, the greater effects of disper-
the longer release time, necessitating a shorter
release time and therefore lower sludge concentration.
fully explained in the comments for the S7-OR1 case above
This is more
(Table 14).
35
-------
Table 25.
The Combined Effects of Increasing Depth to Groundwater from 0 to 1
Meter, Increasing Soil Organic Content from 0.0001 to 0.01, and
Reducing Recharge significantly from 0.5 m/y to 0.00635 m/y.
S12-OR2, D=1M, DIST=OM, FOC=10-2, R=0.00635M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
9.00E-03
1.12E+00
5.14E-02
1.65E-03
1.75E+00
5.00E-03
3.00E-04
2.44E-01
2.09E-03
1.02E-02
9.73E-05
4.00E-03
4.09E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.00E-01
3.60E-02
8.40E+00
3.46E-01
7.00E-03
6.96E+00
2.75E-01
9.68E+01
4.49E+00
1.80E+02
9.46E-01
1.89E-03
2.26E+00
6.30E+02
4.06E+00
3.60E-01
3.32E-01
7.68E-02
1.05E+02
1.15E+01
3.18E-01
1.34E+01
2.75E-01
9.92E+01
1.63E+03
1.80E+02
2.17E+02
1.89E-03
l.OOE+05
6.59E+02
4.06E+00
3.60E-01
% DIFFERENCE
66.0 %
113.3 %
1150.0 %
3223.7 %
4442.9 %
92.5 %
0.0 %
2.5 %
36202.2 %
0.0 %
22838.7 %
0.0 %
4424679.0 %
4.6 %
0.0 %
0.0 %
These results are nearly identical with as those for the S12-OR1
case (Table 19), so the comments for that case apply here. The
unchanged values have release times exceeding travel times so
dispersion is ineffective in reducing peak concentrations. Dispersion
only increases travel time for the peak. For those values changed from
the base case, their travel times exceed their release times, allowing
dispersion to reduce their outflow concentrations and allowing higher
sludge concentrations in the landfill. BEHP is vapor controlled at
this concentration, so groundwater changes have little effect on
allowable concentrations. The lower recharge of 0.00635 m/y for this
case compared with 0.25 m/y for the S12-OR1 case causes a greater
travel time through the unsat- urated zone for all the chemicals. This
significantly increases the allowable dry weight concentrations for
Lindane due to its decay rate of 1. The other chemicals, with
allowable sludge concentrations greater than those of the base case,
have somewhat lower allowable dry weight concentrations in this case
than in the S12-OR1 and S12-0 cases (Tables 19 and 13, respectively)
because the travel times -are not increased proportionally to the
decrease in recharge rate. Therefore, the greater effects of disper-
sion do not cancel the longer release time, necessitating a shorter
release time and therefore lower sludge concentration. This is more
fully explained in the comments for the S7-OR1 case above (Table 14).
36
-------
Table 26.
Base Case for Well 150 Meters from the Boundary.
B4 150 -- Base Case
Concentrations in mg/1.
CHEMICAL AQUIFER VAPOR BCKGRND SUM
HEL
CS
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
4
8
1
1
5
1
5
3
2
1
1
0
4
3
5
5
.92E-02
.93E-03
.OOE+00
.59E-02
.37E-03
.OOE+00
.OOE-03
.OOE-04
.43E-01
.07E-07
.OOE-02
.OOE+00
.OOE-03
.53E-04
.OOE-03
.OOE-03
0
0
0
0
0
0
0
9
2
1
1
1
0
1
0
0
.OOE+00
.OOE+00
.OOE+00
.OOE+00
.OOE+00
.OOE+00
.OOE+00
.90E-12
.12E-03
.38E-04
.99E-04
.OOE-04
.OOE+00
.01E-04
.OOE+00
.OOE+00
4
1
1
1
3
2
0
0
0
0
0
0
0
0
0
0
.OOE-04
.OOE-03
.OOE-02
.OOE-03
.OOE-04
.70E-03
.OOE+00
.OOE+00
.OOE+00
.OOE+00
.OOE+00
.OOE+00
.OOE+00
.OOE+00
.OOE+00
.OOE+00
4
9
1
1
8
1
5
3
2
1
1
1
4
4
5
5
.96E-02
.93E-03
.01E+00
.69E-02
.37E-04
.03E+00
.OOE-03
.OOE-04
.45E-01
.38E-04
.02E-02
.OOE-04
.OOE-03
.54E-04
.OOE-03
.OOE-03
5.
1.
1.
5.
2.
1.
5.
3.
2.
2.
1.
1.
4.
4.
5.
5.
OOE-02
OOE-02
30E+00
OOE-02
OOE-03
75E+00
OOE-03
OOE-04
45E-01
10E-03
02E-02
OOE-04
OOE-03
54E-04
OOE-03
OOE-03
2.40E+01
9.44E+00
l.OOE+04
5.08E+02
2.36E+01
1.00E+.04
8.50E-01
2.50E+02
1.39E+01
l.OOE+04
1.72E+01
7.01E-W
4.92E+01
1.47E+03
5.14E+01
1.11E+00
37
-------
Table 27.
The Effects of Increasing Depth to Groundwater from 0 to 10 Meters.
S7_150, D to GW=10M, DIST=150 M, FOC=10-4, R=0.5M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.5816E+01
1.6935E+01
l.OOOOE+04
1.4406E+03
6.5761E+01
l.OOOOE+04
8.4983E-01
2.5007E+02
1.6298E+03
l.OOOOE+04
3.3527E+02
7.0109E-02
1.3429E+03
1.4717E+03
5.1357E+01
1.1132E+00
% DIFFERENCE
49.7 %
79.4 %
0.0 %
183.7 %
179.2 %
0.0 %
0.0 %
0.0 %
11583.2 %
0.0 %
1850.0 %
0.0 %
2630.0 %
-0.1 %
0.0 %
0.2 %
The chemicals
times so long that
saturated zones is insufficient
that obtained in the base case,
so short in comparison with the
no impact on the final concentration. The two
Chlordane and DMN, which are vapor controlled
unchanged from the base case either have release
the combined dispersion in both the unsaturated and
to reduce the peak concentration below
or the unsaturated zone travel time is
total travel time as to have virtually
exceptions to this are
in both cases so that
depth to groundwater has no effect on final concentration. DMN is an
interesting case because degradation in the saturated zone is so high
that all of the final concentration is attributable to the vapor path-
way.
Chemicals with allowable dry weight concentrations above the base
case generally have total travel times long enough that dispersion can
reduce the peak concentration and allow higher initial concentrations.
The one exception here is Lindane, which benefits not only from
additional dispersion in the unsaturated zone, but also from additional
degradation.
38
-------
Table 28.
The Effects of Increasing Depth to Groundwater from 0 to 10 Meters
and Reducing Recharge from 0.5 to 0.25 m/y at a 150 Meter Well.
S7-150R1, GW 10M, D 150M, R 0.25 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.5205E+01
1.7484E+01
l.OOOOE+04
1.4426E+03
6.5003E+01
l.OOOOE+04
1.6997E+00
5.0033E+02
1.6309E+03
l.OOOOE+04
4.7181E+02
7.0109E-02
l.OOOOE+04
2.4051E+03
1.0271E+02
1.8619E+00
% DIFFERENCE
47.2 %
85.2 %
0.0 %
184.1 %
176.0 %
0.0 %
100.0 %
100.0 %
11591.0 %
0.0 %
2644.2 %
0.0 %
20228.9 %
63.3 %
100.0 %
67.6 %
The reduced recharge levels decrease unsaturated zone travel times
while increasing pulse times. More importantly, they reduce the annual
flux to the saturated zone so there is less contaminant to be diluted
by the aquifer. The effects are minimal for the metals since
geochemistry effects outweigh dilution. Conversely, the organic
contaminants are greatly affected. As a consequence, much higher
sludge concentrations can be accepted. Chlordane and DMN remain
exceptions because their risk levels are driven by vapor considerations
rather than ground water transport. The greater travel time has a big
effect on Lindane since degradation allows for extremely high sludge
concentrations to be mitigated. The copper and nickel are unchanged
because the base case is already at the maximum allowable level of
10,000 mg/kg.
39
-------
Table 29.
The Effects of Increasing Depth to Groundwater from 0 to 10 Meters
and Reducing Recharge from 0.5 to 0.00635 m/y at a 150 Meter Well.
S7-150R2, GW 10M, D 150M, R 0.00635 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
6.3432E+02
l.OOOOE+04
3.5669E+01
l.OOOOE+04
1.6316E+03
l.OOOOE+04
8.4046E+02
7.0125E-02
l.OOOOE+04
6.2055E+03
2.5680E- *?
4.6715E+--1
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
1869.2 %
2593.3 %
0.0 %
4097.1 %
3897.4 %
11596.1 %
0.0 %
4788.4 %
0.0 %
20228.9 %
321.3 %
4900.7 %
4104.0 %
The combined effect of increased travel time from the greater
depth of the unsaturated zone and the low recharge creates greatly
reduced aquifer concentrations because of the enhanced dispersion,
greater time for degradation, and smaller flux of chemical that needs
to be diluted by the groundwater. As a consequence, much higher sludge
concentrations can be tolerated with four exceptions: copper, nickel,
Chlordane, and DMN. Copper and nickel have the maximum concentrations
already allowed in the base case. In the case of Chlordane and DMN,
vapor considerations dictate the risk and, hence, the sludge
concentrations. Therefore, changes in the groundwater pathway have no
impact on criteria levels. The large effects noted for those
contaminants whose concentrations do change reflects the predominance
of saturated zone impacts on overall system risks.
40
-------
Table 30.
The Effects of Increasing Depth to Groundwater from 0 to 10 Meters
and Aquifer Thickness from 15 to 78.6 Meters.
S7-150T1, D to GW=10M, FOC= 0-4, D=150M, AQ=78.6M, R=0.5M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.5816E+01
1.7494E+01
l.OOOOE+04
1.4557E+03
6.6544E+01
l.OOOOE+04
1.7631E+00
4.8870E+02
1.6298E+03
l.OOOOE+04
4.6579E+02
7.0109E-02
2.4416E+03
2.3724E+03
9.3717E+01
2.3095E+00
% DIFFERENCE
49.7 %
85.3 %
0.0 %
186.7 %
182.5 %
0.0 %
107.5 %
95.4 %
11583.2 %
0.0 %
2609.2 %
0.0 %
4863.5 %
61.1 %
82.5 %
107.8 %
The results for increased depth to groundwater and increased
aquifer thickness are almost identical to those for the greater depth
but same aquifer thickness. This suggests that the base case aquifer
thickness is sufficiently large that it does not inhibit vertical
dispersion. The exceptions are B(A)P, Benzene, PCB, TCE, and
Toxaphene. These are the organics that are not driven by vapor
considerations (BEHP, Chlordane, and DMN) or degradation (Lindane).
The inorganics are controlled by geochemistry and do not display
vertical dispersion restrictions under the deeper unsaturated zone
conditions. Copper and Nickel are already at the maximum allowable
concentrations of 10,000 mg/kg.
41
-------
Table 31.
The Effects of Increased Depth to Groundwater from 0 to 10 Meters
and Reduced Aquifer Thickness from 15 to 5 Meters.
S7-150T2, GW 10M, FOC 10-4, D 150M, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
1.7096E+01
8.2636E+00
3.3560E+03
7.0874E+02
3.4037E+01
1.0049E+03
2.8347E-01
8.3400E+01
1.6187E+03
l.OOOOE+04
1.4963E+02
7.0114E-02
4.4835E+02
5.7529E+02
1.7044E+01
3.7113E-01
% DIFFERENCE
-28.5 %
-12.5 %
-66.4 %
39.6 %
44.5 %
-90.0 %
-66.6 %
-66.7 %
11503.6 %
0.0 %
770.3 %
0.0 %
811.4 %
-60.9 %
-66.8 %
-66.6 %
The reduced aquifer thickness decreases the space available for
vertical dispersion and thereby keeps the plume more concentrated than
in the base case. Therefore, most allowable concentrations are smaller
than in the base case even though the larger unsaturated zone would
normally accommodate higher sludge concentrations as in case S7-150
(Table 27). For all the contaminants with negative percent
differences, the saturated zone dispersion effects dominate those in
the unsaturated zone. For mercury and lead, the unsaturated zone
changes override the vertical dispersion effects because geochemistry
controls the groundwater concentrations rather than dispersion. For
Lindane, the added travel time in the unsaturated zone allows for
significant degradation and overrides the loss of dispersion.
Chlordane and DMN concentrations are unaffected by the aquifer changes
because the risks are driven by the vapor pathway. Similarly, the long
unsaturated zone travel time for BEHP makes the vapor pathway dominant
and, therefore, changes in the aquifer properties have no effect on
allowable sludge levels.
42
-------
Table 32.
The Effects of Increased Depth to Groundwater and
Aquifer Thickness, Reduced Recharge.
S7-150R1T1, GW 10M, D 150M, R 0.25M/Y, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
4.2125E+01
1.7679E+01
l.OOOOE+04
1.5347E+03
7.0072E+01
l.OOOOE+04
3.5262E+00
9.7764E+02
1.6298E+03
l.OOOOE+04
5.9757E+02
7.0109E-02
l.OOOOE+04
3.4944E+03
1.8743E+02
3.6333E+00
% DIFFERENCE
76.1 %
87.2 %
0.0 %
202.2 %
197.5 %
0.0 %
314.9 %
290.8 %
11583.2 %
0.0 %
3375.7 %
0.0 %
20228.9 %
137.2 %
265.0 %
227.0 %
This case is almost identical to S7-150 RI (Table 28) where all
changes were the same without the thickened aquifer. The minor effects
that occur are noted with the more retarded contaminants whose slow
velocities allow time for vertical dispersivity to be significant.
This illustrates that for most contaminants, the 15m aquifer thickness
does not constrain dispersivity at 150 meters.
43
-------
Table 33.
The Effects of Increased Depth to Groundwater, Reduced Recharge,
and Thin Aquifer for a 150 Meter Well.
S7-150R1T2, GW 10M, D 150M, R 0.25M/Y, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
1.4461E+01
7.0248E+00
l.OOOOE+04
5.8828E+02
3.0778E+01
2.5236E+03
5.6694E-01
1.6676E+02
1.6187E+03
l.OOOOE+04
2.4487E+02
7.0114E-02
l.OOOOE+04
1.0591E+03
3.4225E+01
6.2051E-01
% DIFFERENCE
-39.5 %
-25.6 %
0.0 %
15.8 %
30.7 %
-74.8 %
-33.3 %
-33.3 %
11503.6 %
0.0 %
1324.2 %
0.0 %
20228.9 %
-28.1 %
-33.4 %
-44.2 %
This case is similar to S7-150 RI (Table 32) with a thin aquifer
and S7-150T2 (Table 31) with reduced recharge. The results most
closely resemble that latter suggesting that the thinning of the
aquifer has more impact than the reduced recharge. Observations are
similar to those made in case S7-150T2 (Table 31) in that Lindane shows
a major change over the base case because the extra depth to
groundwater allows for significant degradation. For lead and mercury,
unsaturated zone considerations still override saturated zone
dispersion. Copper is unaffected because it is already at the maximum
allowed concentration of 10,000 mg/kg.
44
-------
Table 34.
The Effects of Increased Depth to Groundwater, Thick Aquifer,
and Minimal Recharge for a 150 Meter Well.
S7-150R2T1, GW 10M, FOC = 10-4, D 150M, R 0.00635M/Y, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
5.4233E+03
l.OOOOE+04
6.9666E+01
l.OOOOE+04
1.6316E+03
l.OOOOE+04
8.5838E+02
7.0125E-02
l.OOOOE+04
6.4131E+03
4.6861E+03
9.1240E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
1869.2 %
22926.9 %
0.0 %
8097.4 %
3897.4 %
11596.1 %
0.0 %
4892.6 %
0.0 %
20228.9 %
335.4 %
9025.3 %
8110.9 %
The minimal recharge has a significant impact on this case. The
greatly reduced recharge holds contaminant flux to a very small rate
which allows for significant dilution in the aquifer. Once again, the
contaminants not affected by this change are those already at the
maximum allowable level of 10,000 mg/kg (copper and nickel) and those
for which the vapor pathway drives the risk (chlordane and DMN). The
BEHP and Lindane results are similar to the case where only the
unsaturated zone is enlarged (S7-150, Table 27) since the greater
travel time created by this situation allows for vapor loss to become
significant for BEHP and degradation to become significant for Lindane.
45
-------
Table 35.
The Effects of Increased Depth to Groundwater, Thin Aquifer,
and Minimal Recharge for a 150 Meter Well.
S7-150R2T2, GW 10M, FOC = 10-4, D 150M, R 0.00635M/Y, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
3.5272E+03
1.7325E+02
l.OOOOE+04
1.1861E+01
4.1690E+03
1.6187E+03
l.OOOOE+04
7.6921E+02
7.0114E-02
l.OOOOE+04
5.4842E+03
8.5562E+02
1.5513E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
594.6 %
635.6 %
0.0 %
1295.7 %
1566.5 %
11503.6 %
0.0 %
4374.0 %
0.0 %
20228.9 %
272.3 %
1566.2 %
1296.1 %
This case closely resembles the previous case, S7-150R2T1 (Table
34), with a very thin aquifer is place of the thick (78.6 meter) one.
Most contaminants show little change suggesting that vertical
dispersivity is not of much significance for these cases. The minimal
recharge appears to be the factor of greatest consequence in
determining contaminant loading. Once again, copper and nickel are
already at the maximum allowable concentration of 10,000 mg/kg in the
base case and vapor considerations remain dominant for DMN and
chlordane. As a consequence, the aquifer property changes have no
effect on base case results for these four contaminants, BEHP is still
vapor controlled with the deep unsaturated zone and, therefore, shows
the same change as for S7-150 (Table 27) where only the depth to
groundwater was changed.
46
-------
Table 36.
The Effects of Increased Depth to Groundwater and Soil Organic
Content for a 150 Meter Well.
S8-150, GW 10M, FOC 0.01, D 150M, HEL 10-4
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.5227E+01
1.7091E+01
l.OOOOE+04
1.4402E+03
6.5761E+01
l.OOOOE+04
8.5249E-01
4.1008E+02
1.6323E+03
l.OOOOE+04
8.6674E+02
7.0106E-02
l.OOOOE+04
1.4714E+03
5.1359E+01
1.5747E+00
% DIFFERENCE
47.3 %
81.0 %
0.0 %
183.6 %
179.2 %
0.0 %
0.3 %
63.9 %
11601.1 %
0.0 %
4941.2 %
0.0 %
20228.9 %
-0.1 %
0.0 %
41.7 %
This case is similar to S7-150 (Table 27) with higher soil organic
content. The effects compared to the base case are almost identical in
both cases except for Lindane, DDT, and Toxaphene. One would expect
the major impacts to be focused on chemicals with strong interactions
with soil organic matter (i.e., high Koc) and this is the case. The
relative difference for BEHP, Chlordane, and DMN are minimized by the
dominance of vapor considerations. PCBs do not reflect the change
because pulse time is too long for dispersion effect to be significant.
TCE is not well retarded and shows no real response to the increased
organic matter.
47
-------
Table 37.
The Effects of Increased Depth to Groundwater and Soil Organic Content,
Reduced Recharge for a 150 meter Well.
S8-150R1, GW 10M, FOC 0.01, DIST 150M, R 0.25 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.5205E+01
1.7401E+01
l.OOOOE+04
1.4426E+03
6.5003E+01
l.OOOOE+04
1.6997E+00
7.8177E+02
1.6309E+03
l.OOOOE+04
8.7337E+02
7.0109E-02
l.OOOOE+04
2.4051E+03
1.0271E+02
2.5366E+00
% DIFFERENCE
47.2 %
84.3 %
0.0 %
184.1 %
176.0 %
0.0 %
100.0 %
212.5 %
11591.0 %
0.0 %
4979.8 %
0.0 %
20228.9 %
63.3 %
100.0 %
128.3 %
This case is analogous to S7-150RI (Table 28) with a higher soil
organic fraction. The close comparison of results illustrates the
minor affect of soil organic matter compared to that of the deeper
unsaturated zone and reduced recharge. B(A)P, DDT, and Toxaphene show
effects due to the longer unsaturated zone travel times which permit
greater dispersion effects. This impact is not noted for other
contaminants because of large pulse (release) times compared to travel
times.
48
-------
Table 38.
The Effect of Increased Depth to Groundwater and Soil Organic Content,
Minimal Recharge for a 150 Meter Well.
S8-150R2, GW 10M, FOC 0.01, DIST 150M, R 0.00635 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
6.3432E+02
l.OOOOE+04
3.5669E+01
l.OOOOE+04
1.6316E+03
l.OOOOE+04
8.8072E+02
7.0125E-02
l.OOOOE+04
6.2055E+03
2.5680E+03
5.3572E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
1869.2 %
2593.3 %
0.0 %
4097.1 %
3897.4 %
11596.1 %
0.0 %
5022.5 %
0.0 %
20228.9 %
321.3 %
4900.7 %
4721.1 %
This case is analogous to S7-150R2 (Table 29) with a higher soil
organic content. The results are almost identical, suggesting that
recharge effects and unsaturated zone depth are much more significant
here than is soil organic content. The greater unsaturated zone travel
times produced by retardation from zone organic matter effects only DDT
and Toxaphene by allowing for more attenuation in transit.
49
-------
Table 39.
The Effects of Increased Depth to Groundwater and Soil Organic Content,
Thick Aquifer for a 150 Meter Well.
S8-150T1, GW 10M, FOC 0.01, DIST 150M, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.5816E+01
1.7494E+01
l.OOOOE+04
1.4557E+03
6.6544E+01
l.OOOOE+04
1.7631E+00
8.0115E+02
1.6298E+03
l.OOOOE+04
8.7317E+02
7.0109E-02
l.OOOOE+04
2.3724E+03
9.3717E+01
3.2712E+00
% DIFFERENCE
49.7 %
85.3 %
0.0 %
186.7 %
182.5 %
0.0 %
107.5 %
220.3 %
11583.2 %
0.0 %
4978.6 %
0.0 %
20228.9 %
61.1 %
82.5 %
194.4 %
This case is the same as S7-150T1 (Table 30) with a higher soil
organic content. As expected, only the chemicals which interact
strongly with soil organic matter are affected. These are B(A)P, DDT,
Lindane, and Toxaphene. Lindane experiences more degradation because
of the added travel time created by the slower transport velocity due
to retardation. The B(A)P, DDT, and Toxaphene experience more
dispersion because of the slower travel time in the unsaturated zone.
Contaminants such as PCBs have too high a release time for the added
travel time to allow any significant dispersion effects.
50
-------
Table 40.
The Effects of Increased Depth to Groundwater and Soil Organic Matter,
Thin Aquifer for a 150 Meter Well.
S8-150T2, GW 10M, FOC 0.01, DIST 150M, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
1.7096E+01
8.2636E+00
3.4089E+03
7.0874E+02
3.4037E+01
1.0772E+03
2.8347E-01
1.3672E+02
1.6187E+03
l.OOOOE+04
8.3988E+02
7.0114E-02
l.OOOOE+04
5.7529E+02
1.7044E+01
5.2568E-01
% DIFFERENCE
-28.5 %
-12.5 %
-65.9 %
39.6 %
44.5 %
-89.2 %
-66.6 %
-45.3 %
11503.6 %
0.0 %
4785.0 %
0.0 %
20228.9 %
-60.9 %
-66.8 %
-52.7 %
This case resembles S7-150T2 (Table 31) with a higher soil organic
content. Once again, the reduced aquifer thickness stops vertical
dispersion to the point of preventing much of the dilution that occurs
in the base case. The only contaminants greatly affected by the
increased travel time due to retention on soil organic matter are DDT
and Lindane. Other chemicals with high Koc values show modest
increases because the other factors are dominant. The impact to
Lindane concentrations reflect the slower travel time which increases
the amount of Lindane lost to degradation. Effects on DDT reflect the
short pulse time compared to travel times so that enhanced dispersion
still has an impact on allowable levels.
51
-------
Table 41.
The Effect of Increased Depth to Groundwater and Soil Organic Content,
'Thick Aquifer and Reduced Recharge for a 150 Meter Well.
S8-150R1T1, GW 10M, FOC 0.01, DIST 150M, R 0.25M/Y, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
4.1787E+01
1.7640E+01
l.OOOOE+04
1.5347E+03
7.0072E+01
l.OOOOE+04
3.5262E+00
1.5276E+03
1.6298E+03
l.OOOOE+04
8.7682E+02
7.0109E-02
l.OOOOE+04
3.4944E+03
1.8743E+02
4.9536E+00
% DIFFERENCE
74.7 %
86.8 %
0.0 %
202.2 %
197.5 %
0.0 %
314.9 %
510.6 %
11583.2 %
0.0 %
4999.9 %
0.0 %
20228.9 %
137.2 %
265.0 %
345.8 %
This case parallels S7-150R1T1 (Table 32) with higher soil organic
content. Results are virtually identical to those for the previous
case with the exception of three contaminants with high Koc values:
B(A)P, DDT, and Toxaphene. For these three chemicals, the higher
organic fraction increases unsaturated zone travel times thus allowing
for more dispersion. For the other highly retarded chemicals, long
pulse times, degradation (Lindane), and vapor considerations override
the effects arising from slower velocities in the unsaturated zone.
52
-------
Table 42.
The Effects of Increased Depth to Groundwater and Soil Organic Content,
Thin Aquifer and Reduced Recharge for a 150 Meter Well.
S8-150R1T2, GW 10M, FOC 0.01, DIST 150M, R 0.25M/Y, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
1.4461E+01
7.0248E+00
l.OOOOE+04
5.8828E+02
3.0778E+01
2.2231E+03
5.6694E-01
2.5959E+02
1.6187E+03
l.OOOOE+04
8.5861E+02
7.0114E-02
l.OOOOE+04
1.0591E+03
3.4225E+01
8.4514E-01
% DIFFERENCE
-39.5 %
-25.6 %
0.0 %
15.8 %
30.7 %
-77.8 %
33.3 %
3.8 %
11503.6 %
0.0 %
4894.0 %
0.0 %
20228.9 %
-28.1 %
-33.4 %
-23.9 %
This case is parallel to Case S7-150R1T2 (Table 33) with higher
soil organic content. As expected, results are almost identical for
all but the contaminants with strong organic interactions (high Koc
values). Significant increases in allowable sludge concentrations are
observed for B(A)P, DDT, and Toxaphene. These three chemicals have
short enough pulse times to benefit from added dispersion resulting
from the greater retention on soil organic matter. Other retarded
organics do not show these effects because of vapor considerations
(BEHP, Chlordane, and DMN), maximum effects of degradation having
already been attained (Lindane), and excessive release (pulse) times
(PCB).
53
-------
Table 43.
The Effects of Increased Depth to Groundwater and Soil Organic Content,
Thick Aquifer and Minimal Recharge for a 150 Meter Well.
S8-150R2T1, GW 10M, FOC 0.01, DIST 150M, R 0.00635M/Y, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
5.2277E+03
l.OOOOE+04
6.9666E+01
l.OOOOE+04
1.6316E+03
l.OOOOE+04
8.8068E+02
7.0125E-02
l.OOOOE+04
6.4131E+03
4.6861E+03
1.0466E+02
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
1869.2 %
22096.4 %
0.0 %
8097.4 %
3897.4 %
11596.1 %
0.0 %
5022.3 %
0.0 %
20228.9 %
335.4 %
9025.3 %
9318.6 %
This case is the same as S7-150R2T1 (Table 34) with a higher soil
organic content. The results are virtually identical to those for the
prior case with the exception of DDT and Toxaphene. In these cases,
the added travel time resulting from retention on the greater mass of
soil organic matter leads to more dispersion because of the short
release (pulse) times compared to overall travel time. For all other
contaminants, the deeper unsaturated zone and minimal recharge are the
overriding factors.
54
-------
Table 44.
The Effects of Increased Depth to Groundwater and Soil Organic Content,
Thin Aquifer and Minimal Recharge for a 150 Meter Well.
S8-150R2T2, GW 10M, FOC 0.01, DIST 150M, R 0.00635M/Y, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
3.5272E+03
1.7325E+02
l.OOOOE+04
1.1861E+01
5.2772E+03
1.6187E+03
l.OOOOE+04
8.7971E+02
7.0114E-02
l.OOOOE+04
5.4842E+03
8.5562E+02
1.7790E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
594.6 %
635.6 %
0.0 %
1295.7 %
2009.5 %
11503.6 %
0.0 %
5016.7 %
0.0 %
20228.9 %
272.3 %
1566.2 %
1501.0 %
This case is the same as S7-150R2T2 (Table 35) with a higher soil
organic content. The higher organic matter level increases travel time
for chemicals with high Koc values due to retention. Only three such
contaminants are effected in this case: B(A)P, DDT, and Toxaphene.
The other chemicals, as in the previous cases, are dominated by other
factors such as degradation, long release (pulse) times, and vapor
considerations.
55
-------
Table 45.
The Effect of Intermediate Depth to Groundwater
for a 150 Meter Well.
S9_150, GW 5M, UNS FOC 10-4, D 150M, HEL 10-4
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.1503E+01
1.2409E+01
l.OOOOE+04
9.6360E+02
4.6550E+01
l.OOOOE+04
8.4983E-01
2.5007E+02
1.6274E+03
l.OOOOE+04
2.0650E+02
7.0109E-02
3.1398E+02
1.4711E+03
5.1357E+01
1.1132E+00
% DIFFERENCE
31.7 %
31.4 %
0.0 %
89.8 %
97.6 %
0.0 %
0.0 %
0.0 %
11566.0 %
0.0 %
1101.1 %
0.0 %
538.3 %
-0.1 %
0.0 %
0.2 %
This case resembles S7-150 (Table 27) with the unsaturated zone
increased only half as much (i.e., 5 meters in place of 10 meters). As
would be expected, the effect is noted on those contaminants for which
added time of travel in the unsaturated zone allows for more dispersion
or degradation. The effect is less than that noted with a 10 meter
depth, but not as much as a factor of 2. The effect on Lindane is
almost identical because 5 meters provides enough time for most of the
chemical to degrade. Chemicals with large release (pulse) times
compared to travel times do not display the increased allowable
concentrations because the added dispersion does not affect peak
height. Basically, the conclusions are the same as those for S7-150
(Table 27), the effects are less pronounced.
56
-------
Table 46.
The Effect of Intermediate Depth to Groundwater, Reduced
Recharge for a 150 Meter Well.
S9-150R1, GW 5M, DIST 150M, R 0.25 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.5335E+01
1.6381E+01
l.OOOOE+04
1.3778E+03
6.5385E+01
l.OOOOE+04
1.6997E+00
5.0014E+02
1.6274E+03
l.OOOOE+04
3.2181E+02
7.0109E-02
2.2535E+03
2.4059E+03
1.0271E+02
1.8615E+00
% DIFFERENCE
47.7 %
73.5 %
0.0 %
171.3 %
177.6 %
0.0 %
100.0 %
99.9 %
11566.0 %
0.0 %
1771.8 %
0.0 %
4481.1 %
63.3 %
100.0 %
67.5 %
The case is the same as S7-150R1 (Table 28) with the depth
increase at 5 meters instead of 10. The results are almost identical
with the exception of Lindane. Since Lindane is degradable, the
shorter travel time with 5 meters of unsaturated zone accommodates much
less degradation. Therefore, allowable sludge levels do not increase
nearly as much here as they did in S7-150R1 (Table 28).
57
-------
Table 47.
The Effect of Intermediate Depth to Groundwater with
Minimal Recharge at a 150 Meter Well.
S9-150R2, GW 5M, DIST 150M, R 0.00635 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
6.4942E+03
3.1785E+02
l.OOOOE+04
3.5669E+01
l.OOOOE+04
1.6316E+03
l.OOOOE+04
8.0313E+02
7.0125E-02
l.OOOOE+04
6.2055E+03
2.5680E+03
4.6715E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
1178.8 %
1249.6 %
0.0 %
4097.1 %
3897.4 %
11596.1 %
0.0 %
4571.3 %
0.0 %
20228.9 %
321.3 %
4900.7 %
4104.0 %
This case is the same as S7-150R2 (Table 29) with a smaller
increase in the depth of the unsaturated zone. Most of the results are
identical illustrating the predominance of the recharge over the
unsaturated travel time differences. Lead, mercury, and DDT show
smaller changes with the reduced unsaturated zone. All are attenuated
by retention on soil sufficiently that the unsaturated zone delays
create sufficient dispersion effects to be observed over and above the
effect of low recharge.
58
-------
Table 48.
The Effect of Intermediate Depth to Groundwater, Thick Aquifer.
S9-150T1, GW 5M, DIST 150M, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.1536E+01
1.2466E+01
l.OOOOE+04
9.9019E+02
4.6553E+01
l.OOOOE+04
1.7631E+00
4.8882E+02
1.6298E+03
l.OOOOE+04
3.1618E+02
7.0109E-02
2.3392E+03
2.3724E+03
9.3717E+01
2.3108E+00
% DIFFERENCE
31.8 %
32.0 %
0.0 %
95.0 %
97.7 %
0.0 %
107.5 %
95.4 %
11583.2 %
0.0 %
1739.0 %
0.0 %
4655.3 %
61.1 %
82.5 %
108.0 %
This case is analogous to S7-150T1 (Table 30) with only half the
depth to the unsaturated zone. Most results are identical except for
five retarded chemicals: arsenic, cadmium, lead, mercury, and DDT.
For these, the unsaturated zone depth is an overriding factor and
allowable increases are proportional to the unsaturated depth ratios,
i.e., the 5 meter values are roughly have the 10 meter values.
Comparison with the identical case with a thinner aquifer S9-150 (Table
45) reveals that the added aquifer thickness affects only organic
constituents with retarded velocities which provide enough travel time
for added depth to allow for concentration changes arising from
vertical dispersivity. BEHP, Chlordane, and DMN are not affected
because vapor considerations are overriding for these three
contaminants.
59
-------
Table 49.
The Effect of Intermediate Depth to Groundwater and
Thin Aquifer for a 150 Meter Well.
S9-150T2, GW 5M, FOC = 10-4, DIST 150M, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
1.5879E+01
7.1807E+00
2.8862E+03
6.0737E+02
2.9224E+01
1.0646E+03
2.8347E-01
8.3400E+01
1.6174E+03
l.OOOOE+04
8.1765E+01
7.0114E-02
1.0488E+02
5.7529E+02
1.7044E+01
3.7113E-01
% DIFFERENCE
-33.6 %
-23.9 %
-71.1 %
19.6 %
24.1 %
-89.4 %
-66.6 %
-66.7 %
11494.3 %
0.0 %
375.6 %
0.0 %
113.2 %
-60.9 %
-66.8 %
-66.6 %
This case is the same as S7-150T2 (Table 31) with only half the
depth of unsaturated zone. The results are nearly the same as for the
previous case except for DDT and Lindane where the smaller unsaturated
zone allows for less dispersion and degradation, respectively. For all
other contaminants, the thin aquifer reduces vertical dispersion and
impacts concentrations to the point of overriding the unsaturated zone
travel time effects. When compared to S9-150 (Table 45), the impact of
the thin aquifer is very clear with all allowable concentrations
dropping significantly save those for BEHP, Chlordane, and DMN. These
three contaminants have risks driven by vapor considerations and,
therefore, do not respond to changes in the aquifer dimensions.
60
-------
Table 50.
The Effect of Intermediate Depth to Groundwater, Thick Aquifer and
Reduced Recharge for a 150 Meter Well.
S9-150R1T1, GW 5M, DIST 150M, R 0.25M/Y, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.7921E+01
1.7916E+01
l.OOOOE+04
1.3902E+03
6.5950E+01
l.OOOOE+04
3.5262E+00
9.7764E+02
1.6298E+03
l.OOOOE+04
4.5164E+02
7.0109E-02
l.OOOOE+04
3.4944E+03
1.8743E+02
3.6333E+00
% DIFFERENCE
58.5 %
89.7 %
0.0 %
173.8 %
180.0 %
0.0 %
314.9 %
290.8 %
11583.2 %
0.0 %
2526.9 %
0.0 %
20228.9 %
137.2 %
265.0 %
227.0 %
This case is similar to S7-150R1TS (Table 32) with only half the
depth of unsaturated zone. The results are roughly comparable with
only DDT having a significantly lower concentration corresponding to
the shallower unsaturated zone. All other chemicals show little or no
effect from the commensurate decrease in unsaturated zone travel time.
When compared to Case S9-150 (Table 46), most of the organic
constituents (except for those driven by vapor considerations [BEHP,
Chlordane, and DMN]) have increased allowable sludge concentrations as
a result of the greater depth for vertical dispersion. This suggests
that at 150 meters distance, the 15 m aquifer restricts vertical
dispersion for organics. Effects are much less notable for metals
where concentrations are controlled by geochemistry.
61
-------
Table 51.
The Effect of Intermediate Depth to Groundwater, Reduced
Recharge and a Thin Aquifer for a 150 Meter Well.
S9-150R1T2, GW 5M, DIST 150M, R 0.25M/Y, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.-9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
1.8292E+01
8.3260E+00
5.3496E+03
7.3004E+02
3.4365E+01
6.4859E+03
5.6694E-01
1.6658E+02
1.6243E+03
l.OOOOE+04
1.4185E+02
7.0114E-02
l.OOOOE+04
1.0591E+03
3.4225E+01
6.2009E-01
% DIFFERENCE
-23.5 %
11.8 %
-46.5 %
43.8 %
45.9 %
-35.1 %
-33.3 %
-33.4 %
11543.7 %
0.0 %
725.0 %
0.0 %
20228.9 %
-28.1 %
-33.4 %
-44.2 %
This case is similar to S9-150R1 (Table 46) with only one-third
the aquifer thickness. Results demonstrate that the impact is on all
contaminants except BEHP, Chlordane, and DMN where risks are driven by
vapor considerations. With these exceptions, it would appear that all
chemicals are vertical dispersion limited in the thin aquifer and,
therefore, cannot be diluted in transit as they would in thicker
aquifers. The changes are of a lower magnitude than those observed in
S9-150T2 (Table 49) with greater recharge. This illustrates how the
reduced rate mitigates some of the effect of the thin aquifer.
62
-------
Table 52.
The Effect of Intermediate Depth to Groundwater and Minimal
Recharge in a Thick Aquifer for a 150 Meter Well.
S9-150R2T1, GW 5M, DIST 150M, R 0.00635M/Y, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
5.7180E+03
l.OOOOE+04
6.9666E+01
l.OOOOE+04
1.6316E+03
l.OOOOE+04
8.3665E+02
7.0125E-02
l.OOOOE+04
6.4131E+03
4.6861E+03
9.1326E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
1869.2 %
24178.2 %
0.0 %
8097.4 %
3897.4 %
11596.1 %
0.0 %
4766.2 %
0.0 %
20228.9 %
335.4 %
9025.3 %
8118.7 %
Results are almost identical to those for S7-150R2T1 (Table 34)
where conditions are the same except for the depth to groundwater. The
affects of the minimal recharge clearly overwhelm any effects from the
extra 5 meters of unsaturated depth. Comparison to S9-150R2 (Table 47)
shows increases in allowable sludge concentrations for only four
contaminants: Lead, Mercury, TCE, and Toxaphene. These are apparently
the only contaminants for which the thinner aquifer significantly
affects vertical dispersion where the greater dispersion is useful in
reducing peak concentrations. In all other cases pulse times are too
large or other considerations too dominant for the aquifer thickness to
be significant.
63
-------
Table 53.
The Effects of Intermediate Depth to Groundwater and Minimal
Recharge in a Thin Aquifer for a 150 Meter Well.
S9-150R2T2, GW 5M, DIST 150M, R 0.00635M/Y, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
1.7634E+03
8.7264E+01
l.OOOOE+04
1.1861E+01
4.1690E+03
1.6187E+03
l.OOOOE+04
6.8234E+02
7.0114E-02
l.OOOOE+04
5.4842E+03
8.5562E+02
1.5513E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
247.2 %
270.5 %
0.0 %
1295.7 %
1566.5 %
11503.6 %
0.0 %
3868.7 %
0.0 %
20228.9 %
272.3 %
1566.2 %
1296.1 %
Comparison to Case S7-150R2T2 with twice the unsaturated zone
depth shows that only Lead, Mercury, and DDT are affected. All other
contaminants are virtually identical because of the overriding effects
of minimal recharge. These three slow-moving chemicals change with
reduced unsaturated zone depths because their pulse times (releases)
are short compared to travel times. When compared to Case S9-150R2
(Table 47), this case suggests that most slow-moving contaminants are
hindered by the restricted aquifer thickness because they cannot
disperse as far as they otherwise might. These effects are not
observed when vapor considerations (BEHP, Chlordane, and DMN) or
degradation (Lindane) are overriding factors.
64
-------
Table 54.
The Effect of Intermediate Depth to Groundwater with
Increased Soil Organic Content
S10-150, GW 5M, FOC 0.01, D 150M, HEL 10-4, R 0.5 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.1372E+01
1.2448E+01
l.OOOOE+04
9.8871E+02
4.6550E+01
l.OOOOE+04
8.5249E-01
2.8002E+02
1.6322E+03
l.OOOOE+04
8.5320E+02
7.0125E-02
l.OOOOE+04
1.4723E+03
5.1359E+01
1.1823E+00
% DIFFERENCE
31.2 %
31.8 %
0.0 %
94.7 %
97.6 %
0.0 %
0.3 %
11.9 %
11600.4 %
0.0 %
4862.5 %
0.0 %
20228.9 %
0.0 %
0.0 %
6.4 %
This case is similar to S8-150 (Table 36) but with only half the
unsaturated zone depth. As expected, concentrations are about half
those for all chemicals where the unsaturated zone travel time is
significant for dispersion. Vapor driven chemicals (BEHP, Chlordane,
and DMN) are unaffected as is Lindane where degradation is sufficient
at either travel time to drive allowable concentrations to the limits.
The unsaturated depth change is also inconsequential for those
contaminants where release times are large compared to travel times so
the added dispersion is not noticeable. This case is also similar to
S9-150 (Table 45) with a much greater soil organic content. As
expected, the results are very similar between the two cases except for
B(A)P, DDT, Lindane, and Toxaphene which are all highly attenuated and,
therefore, greatly retarded by the presence of large fractions of soil
organic matter.
65
-------
Table 55.
The Effect of Intermediate Depth to Groundwater with Increased Soil
Organic Content and Reduced Recharge at a 150 Meter Well.
S10-150R1, GW 5M, FOC 0.01, DIST 150M, R 0.25 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN -
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
-KjOQQOE'04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.5015E+01
1.6381E+01
l.OOOOE+04
1.3778E+03
6.5385E+01
l.OOOOE+04
1.6997E+00
5.4960E+02
1.6274E+03
l.OOOOE+04
8.6594E+02
7.0109E-02
l.OOOOE+04
2.4059E+03
1.0271E+02
1.9391E+00
% DIFFERENCE
46.4 %
73.5 %
0.0 %
171.3 %
177.6 %
0.0 %
100.0 %
119.7 %
11566.0 %
0.0 %
4936.6 %
0.0 %
20228.9 %
63.3 %
100.0 %
74.5 %
These results compare closely with those for S8-150R1 (Table 37)
where the conditions were the same except for a deeper unsaturated
zone. Only B(A)P is significantly effected by the longer travel times
which allow for more dispersion. For the other contaminants, the high
organic content and reduced recharge provide the greatest effects on
allowable sludge concentrations. When compared to case S9-150R1 (Table
46), this case provides marked increases in allowable sludge levels for
organic constituents not driven by vapor considerations (BEHP,
Chlordane, and DMN) or degradation (Lindane). These increases reflect
the longer travel times creates by retention on soil organic matter.
66
-------
Table 56.
The Effect of Intermediate Depth to Groundwater and Increased Soil
Organic Content with Minimal Recharge at a 150 Meter Well.
S10-150R2, GW 5M, FOC 0.01, DIST 150M, R 0.00635 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
6.4834E+03
3.2128E+02
l.OOOOE+04
3.5669E+01
l.OOOOE+04
1.6321E+03
l.OOOOE+04
8.7687E+02
7.0125E-02
l.OOOOE+04
6.2055E+03
2.5680E+03
4.6745E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
1176.7 %
1264.1 %
0.0 %
4097.1 %
3897.4 %
11599.6 %
0.0 %
5000.2 %
0.0 %
20228.9 %
321.3 %
4900.7 %
4106.7 %
When compared to the same conditions with twice the unsaturated
zone depth in Case S7-150R2 (Table 29), these results are nearly
identical except for Lead and Mercury. These slower moving metals
achieve less dispersion during the shortened unsaturated travel time.
Ttre results are identical for Case S9-150R2 (Table 47) which has less
soil organic content. This illustrates that minimal recharge effects
dominate other considerations such as soil organic content.
67
-------
Table 57.
The Effect of Intermediate Depth to Aquifer and Increased Soil
Organic Content with a Thick Aquifer for a 150 Meter Well.
S10-150T1, GW 5M, FOC 0.01, DIST 150M, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.1536E+01
1.2466E+01
l.OOOOE+04
9.6583E+02
4.6553E+01
l.OOOOE+04
1.7631E+00
5.4748E+02
1.6298E+03
l.OOOOE+04
8.6550E+02
7.0109E-02
l.OOOOE+04
2.3724E+03
9.3717E+01
2.4448E+00
% DIFFERENCE
31.8 %
32.0 %
0.0 %
90.2 %
97.7 %
0.0 %
107.5 %
118.9 %
11583.2 %
0.0 %
4934.0 %
0.0 %
20228.9 %
61.1 %
82.5 %
120.0 %
This case is similar to Case S9-150T1 (Table 48) with greater soil
organic content. The results are comparable except for B(A)P and DDT
whose high Koc values cause greater retention in the unsaturated zone
allowing for more dispersion.
68
-------
Table 58.
The Effect of Intermediate Depth to Groundwater and Increased Soil
Organic Content with a Thin Aquifer for a 150 Meter Well.
S10-150T2, GW 5M, FOC 0.01, DIST 150M, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
1.5879E+01
7.1807E+00
2.8862E+03
6.1028E+02
2.9224E+01
1.0144E+03
2.8347E-01
9.3358E+01
1.6174E+03
l.OOOOE+04
8.0249E+02
7.0114E-02
l.OOOOE+04
5.7529E+02
1.7044E+01
3.9315E-01
% DIFFERENCE
-33.6 %
-23.9 %
-71.1 %
20.2 %
24.1 %
-89.9 %
-66.6 %
-62.7 %
11494.3 %
0.0 %
4567.5 %
0.0 %
20228.9 %
-60.9 %
-66.8 %
-64.6 %
This case is like S9-150T2 (Table 49) with greater soil organic
content. The results are virtually the same except for DDT and Lindane
where attenuation is significant. In the first case, the slower
resulting travel time allows for more dispersion. In the second case
it allows for more degradation of Lindane.
69
-------
Table 59.
The Effect of Intermediate Depth to Groundwater, Increased Soil
' Organic Content at Reduced Recharge in a Thick Aquifer
for a 150 Meter Well.
S10-150R1T1, GW 5M, FOC 0.01, DIST 150M, R 0.25M/Y, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
4.0664E+01
1.7916E+01
l.OOOOE+04
1.3902E+03
6.5950E+01
l.OOOOE+04
3.5262E+00
1.0743E+03
1.6298E+03
l.OOOOE+04
8.7269E+02
7.0109E-02
l.OOOOE+04
3.4944E+03
1.8743E+02
3.7847E+00
% DIFFERENCE
70.0 %
89.7 %
0.0 %
173.8 %
180.0 %
0.0 %
314.9 %
329.4 %
11583.2 %
0.0 %
4975.8 %
0.0 %
20228.9 %
137.2 %
265.0 %
240.6 %
This case is similar to Case S9-150R1T1 (Table 50) except it has
higher soil organic content. As one would expect, the resulting
impacts are small except for DDT which is highly attenuated and
experiences greater dispersion with the extended unsaturated zone
travel times.
70
-------
Table 60.
The Effect of Intermediate Depth to Groundwater and Increased Soil
Organic Matter with Reduced Recharge in a Thin Aquifer
for a 150 Meter Well.
S10-150R1T2, GW 5M, FOC 0.01, DIST 150M, R 0.25M/Y, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
1.8500E+01
8.2215E+00
5.5573E+03
7.2977E+02
3.4423E+01
3.4534E+03
5.6694E-01
1.8324E+02
1.6187E+03
l.OOOOE+04
8.3735E+02
7.0114E-02
l.OOOOE+04
1.0591E+03
3.4225E+01
6.4613E-01
% DIFFERENCE
-22.7 %
-12.9 %
-44.4 %
43.7 %
46.2 %
-65.5 %
-33.3 %
-26.8 %
11503.6 %
0.0 %
4770.3 %
0.0 %
20228.9 %
-28.1 %
-33.4 %
-41.9 %
This case is comparable with S9-150R1T2 (Table 51) except that
there is greater soil organic content. As one would expect, the
results are also comparable except for those for DDT and B(A)P which
are highly attenuated and undergo greater dispersion as a result of the
longer travel times.
71
-------
Table 61.
The Effect of Intermediate Depth and Increased Soil Organic Content
with Minimal Recharge in a Thick Aquifer for a 150 Meter Well.
S10-150R2T1, GW 5M, FOC 0.01, DIST 150M, R 0.00635M/Y, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
5.9411E+03
l.OOOOE+04
6.9666E+01
l.OOOOE+04
1.6316E+03
l.OOOOE+04
8.8068E+02
7.0125E-02
l.OOOOE+04
6.4131E+03
4.6861E+03
9.2104E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
1869.2 %
25125.5 %
0.0 %
8097.4 %
3897.4 %
11596.1 %
0.0 %
5022.3 %
0.0 %
20228.9 %
335.4 %
9025.3 %
8188.7 %
This case is comparable to Case S9-150R2T1 (Table 52) only this
case has higher soil organic content. The results are almost identical
between the two cases revealing that the minimal recharge overrides
other factors.
72
-------
Table -62.
The Effect t>? Intermediate Depth to Eroundwater and Jncreased Soil
Organic Content with Minimal Recharge in a Thin Aquifer at
* 150 Meter
S10-15DRZT2, EW 5M, FOC 0.01, DIST 15DM, H D.DD535M/Y, AQ 5 J
tHEMTCAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
HEAL ALLOWABLE SLUDGE
STANDARD CONCENTRATION (Mfi/Kfi)
(MG/JJ BASELINE SEAISJTJVJTY % OlffERENCf
5.0000E-02
JLOOOQE-02
1.3000E+00
5.000OT-TJ2
1.7500E+00
3.DOOOE-04
2.4800E-01
2.1000E-03
1.TOUDE-D2
J.OOOOE-04
-4.0000E-03
4.540UE-04
5.0000E-D3
2.3920E-t-01
l.OOOOE-t-04
5.07B2E-t-02
1.1
1.QQQQE+Q4
l.DQQQE+M
1.7634E+03
S.7264E+Q1
l.OOOOE-i-04
S.4985E-01
l!3950E+01
4.2B32E+03
1.6187E+03
1.7193E-I-01
7.t)lllE-02
4.9191E+01
5.1333I+D1
B.7B43E402
7.0114E-02
1.0000E-i-T)4
5_4S42f^3
J-.5562E4-JD2
1.5513E-HH
41706.0 %
105810.9 %
JLfl %
247.2 %
270.5 %
0.0 %
1295.7 %
1512.2 %
11503.6 %
0.0 %
5009.2 %
0.0 %
2022B/9 %
272.3 %
1566,2 %
1796.1 %
This case is comparable to Case S9-150R2T2 (Table 53) but with a
higher soil organic content. The results are virtually identical
except for UDT -whfcfr "fc** -sHfrixrTtmxly -nrgTi a-rcentfatitm properties to
benefit from the higher organic content. Even here the effect is small
because of the dominant influence of minimal recharge.
73
-------
Table 63.
The Effect of Minimal Depth to Groundwater.
Sll 150, GW 1M, UNS FOC 10-4, D 150M, HEL 10-4
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
2.4017E+01
9.6310E+00
l.OOOOE+04
5.3134E+02
2.5758E+01
l.OOOOE+04
8.4983E-01
2.5007E+02
1.6080E+03
l.OOOOE+04
5.1259E+01
7.0109E-02
7.5017E+01
1.4711E+03
5.1357E+01
1.1132E+00
% DIFFERENCE
0.4 %
2.0 %
0.0 %
4.6 %
9.4 %
0.0 %
0.0 %
0.0 %
11426.9 %
0.0 %
198.1 %
0.0 %
52.5 %
-0.1 %
0.0 %
0.2 %
This case differs from the base case only in that it has an
unsaturated zone albeit s small one. Significant effects occur only
for BEHP, DDT, and Lindane. All are highly attenuated. The BEHP is so
slow to move that the risk reverts to the vapor pathway. The added
time of travel for Lindane allows for degradation. For DDT, the pulse
(release) time is small enough that the added travel time allows for
dispersion to reduce groundwater concentrations.
74
-------
Table 64.
The Effect of Minimal Depth to Groundwater and Reduced
Recharge at a 150 Meter Well.
S11-150R1, GW 1M, DIST 150M, R 0.25 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.6776E+01
1.6312E+01
l.OOOOE+04
6.2215E+02
3.0978E+01
l.OOOOE+04
1.7050E+00
5.0030E+02
1.6079E+03
l.OOOOE+04
9.1805E+01
7.0125E-02
2.0926E+02
2.4077E+03
1.0272E+02
1.8686E+00
% DIFFERENCE
53.7 %
72.8 %
0.0 %
22.5 %
31.5 %
0.0 %
100.6 %
100.0 %
11426.2 %
0.0 %
434.0 %
0.0 %
325.4 %
63.5 %
100.0 %
68.2 %
When compared to Case S9-150R1 (Table 46), this case with an even
shallower unsaturated zone, most chemicals have similar results because
of the relative unimportance of the unsaturated zone in overall
attenuation mechanisms. Those that are affected (Lead, Mercury, DDT,
and Lindane) are all slower moving contaminants with small release
(pulse) times compared to travel times. For these, the longer travel
times allow more dispersion and degradation which results in higher
allowable sludge concentrations.
75
-------
Table 65.
The Effect of Minimal Depth to Groundwater and Minimal
Recharge at a 150 Meter Well.
S11-150R2, GW 1M, DIST 150M, R 0.00635 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
1.5021E+03
7.4890E+01
l.OOOOE+04
3.5669E+01
l.OOOOE+04
1.6316E+03
l.OOOOE+04
6.0039E+02
7.0125E-02
l.OOOOE+04
6.2055E+03
2.5680E+03
4.6715E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
195.8 %
218.0 %
0.0 %
4097.1 %
3897.4 %
11596.1 %
0.0 %
3392.1 %
0.0 %
20228.9 %
321.3 %
4900.7 %
4104.0 %
This case is similar to Case S9-150R2 (Table 47) with a shallower
unsaturated zone. The results are nearly identical except for those
for Lead, Mercury, and DDT which are all slow moving enough and have
short enough release times to benefit from the extra dispersion that
comes with the longer unsaturated zone travel times. For all other
contaminants, the minimal recharge effects dominates all others.
76
-------
Table 66.
The Effect of Minimal Depth to Groundwater in a
Thick Aquifer at a 150 Meter Well.
S11-150T1, GW 1M, DIST 150M, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3'OOOE+OO
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
2.4128E+01
9.6949E+00
l.OOOOE+04
5.3150E+02
2.5881E+01
l.OOOOE+04
1.7631E+00
4.8882E+02
1.6198E+03
l.OOOOE+04
8.9369E+01
7.0109E-02
5.5788E+02
2.3724E+03
9.3717E+01
2.3108E+00
% DIFFERENCE
0.9 %
2.7 %
0.0 %
4.7 %
9.9 %
0.0 %
107.5 %
95.4 %
11511.5 %
0.0 %
419.8 %
0.0 %
1034.1 %
61.1 %
82.5 %
108.0 %
This case is like S9-1150T1 (Table 48) with a thinner unsaturated
zone. The results are closer to the base case for most metals because
the shortened travel time leads to less dispersion effects. The
attenuation largely arises from geochemistry. The organics on the
other hand have large retardation factors and so gain more
proportionately from the small unsaturated zone. Some also remain the
same because only a little retardation is required to allow vapor
considerations or degradation to become the overriding factor. Results
are similar to those in Case Sll-150 (Table 63) for metals but have
much higher allowable sludge concentrations for
velocities allow for more vertical dispersion in
This suggests that most organics are constrained
15 meter aquifer at a 150 meter distance.
organics whose slow
the thicker aquifer.
in dispersing by the
77
-------
Table 67.
The Effect of Minimal Depth to Groundwater in a
Thin Aquifer at a 150 Meter Well.
S11-150T2, GW 1M, DIST 150M, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
1.1112E+00
1.4585E+01
6.6166E+00
2.8312E+03
4.9851E+02
2.4117E+01
1.0807E+03
2.8347E-01
8.3400E+01
1.5611E+03
l.OOOOE+04
1.7782E+01
7.0114E-02
2.4971E+01
5.7529E+02
1.7044E+01
3.7113E-01
4.6715E+01
% DIFFERENCE
-39.0 %
-29.9 %
-71.7 %
-1.8 %
2.4 %
-89.2 %
-66.6 %
-66.7 %
11090.7 %
0.0 %
3.4 %
0.0 %
-49.2 %
-60.9 %
-66.8 %
-66.6 %
4104.0 %
When compared to Case Sll 150 (Table 63) this case with a thinner
aquifer clearly shows the effects of constrained vertical dispersion.
Only BEHP, Chlordane, and DMN remain unaffected because their allowable
concentrations are driven by vapor considerations which are unaffected
by aquifer characteristics.
78
-------
Table 68.
The Effect of Minimal Depth to Groundwater and Reduced Recharge
in a Thick Aquifer at a 150 Meter Well.
S11-150R1T1, GW 1M, DIST 150M, R 0.25M/Y, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.6940E+01
1.7491E+01
l.OOOOE+04
6.2480E+02
3.0829E+01
l.OOOOE+04
3.5262E+00
9.7664E+02
1.6256E+03
l.OOOOE+04
1.5446E+02
7.0109E-02
1.5748E+03
3.4944E+03
1.8743E+02
3.6391E+00
% DIFFERENCE
54.4 %
85.2 %
0.0 %
23.0 %
30.9 %
0.0 %
314.9 %
290.4 %
11553.0 %
0.0 %
798.4 %
0.0 %
3101.4 %
137.2 %
265.0 %
227.5 %
The results in this case are similar to those in Case S11-150R1
(Table 64) which has a thinner aquifer except for the organic
contaminants which are not driven by vapor considerations. For the
bulk of the organics, the thicker aquifer allows for more dispersion of
the contaminant leading to higher allowable sludge concentrations. It
appears that for these contaminants, the 15 meter aquifer thickness
constrains vertical dispersion over the 150 meter travel distance.
79
-------
Table 69.
The Effect of Minimal Depth to Groundwater and Reduced Recharge
in a Thin Aquifer at a 150 Meter Well.
S11-150R1T2, GW 1M, DIST 150M, R 0.25M/Y, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
1.6064E+01
7.1561E+00
4.1999E+03
5.3451E+02
2.6360E+01
5.1574E+03
5.6694E-01
1.6658E+02
1.5935E+03
l.OOOOE+04
3.2831E+01
7.0114E-02
1.5748E+03
1.0591E+03
3.4225E+01
6.2009E-01
% DIFFERENCE
-32.8 %
-24.2 %
-58.0 %
5.3 %
11.9 %
-48.4 %
-33.3 %
-33.4 %
11322.9 %
0.0 %
91.0 %
0.0 %
3101.4 %
-28.1 %
-33.4 %
-44.2 %
This case is similar to Case S11-150R1 (Table 64) with a thinner
aquifer. The results are all much lower allowable sludge
concentrations with the exception of BEHP, Chlordane, and DMN where the
risks are driven by vapor considerations. The lower allowable levels
are a direct reflection of limitations on vertical dispersion which
greatly reduces dilution between the source and the well.
80
-------
Table 70.
The Effect of Minimal Depth to Groundwater and Minimal Recharge
in a Thick Aquifer at a 150 Meter Well.
S11-150R2T1, GW 1M, DIST 150M, R 0.00635M/Y, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
5.1286E+03
l.OOOOE+04
6.9666E+01
l.OOOOE+04
1.6316E+03
l.OOOOE+04
7.0154E+02
7.0125E-02
l.OOOOE+04
6.4131E+03
4.6861E+03
9.1326E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
1869.2 %
21675.6 %
0.0 %
8097.4 %
3897.4 %
11596.1 %
0.0 %
3980.4 %
0.0 %
20228.9 %
335.4 %
9025.3 %
8118.7 %
This case is similar to Case S11-150R2 (Table 65) with a thicker
aquifer. The results are comparable except for some of the slower
moving chemicals such as Lead, Mercury, Benzene, TCE, and Toxaphene
where the added aquifer depth allows for more vertical dispersion and,
therefore, higher allowable sludge concentrations. For the most part,
the minimal recharge dominates the effects leaving little room for
further increases from the greater aquifer thickness.
81
-------
Table 71.
S11-150R2T2, GW 1M, DIST 150M, R 0.00635M/Y, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
4.3751E+02
2.1325E+01
l.OOOOE+04
1.1861E+01
4.1690E+03
1.6187E+03
l.OOOOE+04
3.6631E+02
7.0114E-02
l.OOOOE+04
5.4842E+03
8.5562E+02
1.5513E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
-13.8 %
-9.5 %
0.0 %
1295.7 %
1566.5 %
11503.6 %
0.0 %
2030.6 %
0.0 %
20228.9 %
272.3 %
1566.2 %
1296.1 %
This case is similar to Case S11-150R2 (Table 65) but has a
thinner aquifer. The effect of the reduced area for vertical mixing
and dispersion is most prominent with slow moving metals and organics.
Unchanged are the organics driven by vapor considerations, the metals
controlled by geochemistry and metals with brief release (pulse) times
which are strongly affected by the low recharge levels.
82
-------
Table 72.
The Effect of Minimal Depth to Groundwater with High Soil
Organic Content at a 150 Meter Well.
S12 150, GW 1M, FOC 0.01, D 150M, HEL 10-4
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
2.4212E+01
9.7000E+00
l.OOOOE+04
5.3200E+02
2.5858E+01
l.OOOOE+04
8.5249E-01
2.5015E+02
1.6320E+03
l.OOOOE+04
7.5758E+02
7.0125E-02
l.OOOOE+04
1.4723E+03
5.1359E+01
1.1174E+00
% DIFFERENCE
1.2 %
2.7 %
0.0 %
4.8 %
9.8 %
0.0 %
0.3 %
0.0 %
11598.9 %
0.0 %
4306.3 %
0.0 %
20228.9 %
0.0 %
0.0 %
0.6 %
This case is comparable to Sll-150 (Table 63) with higher soil
organic content. The results are very similar except for DDT and
Lindane. In the first case, the added attenuation affords greater
dispersion effects, while in the second the delays allow more time for
degradation.
83
-------
Table 73.
The Effect of Minimal Depth to Groundwater and High Soil Organic
Content with Reduced Recharge at a 150 Meter Well.
S12-150R1, GW 1M, FOC 0.01, DIST 150M, R 0.25 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.7630E+01
1.6891E+01
l.OOOOE+04
6.2448E+02
3.0901E+01
l.OOOOE+04
1.6997E+00
5.0115E+02
1.6274E+03
l.OOOOE+04
8.1063E+02
7.0109E-02
l.OOOOE+04
2.4059E+03
1.0271E+02
1.8609E+00
% DIFFERENCE
57.3 %
78.9 %
0.0 %
23.0 %
31.2 %
0.0 %
100.0 %
100.3 %
11566.0 %
0.0 %
4614.9 %
0.0 %
20228.9 %
63.3 %
100.0 %
67.5 %
This case is similar to Case S11-150R1 (Table 64) with higher soil
organic content. The results are virtually identical for all but DDT
and Lindane. For other well attenuated chemicals, the unsaturated zone
is too small for the organic content to have a major impact. For DDT,
the attenuation is large enough to enhance dispersion while for Lindane
it allows significantly more degradation.
84
-------
Table 74.
The Effect of Minimal Depth to Groundwater and Increased Soil
Organic Matter with Minimal Recharge at a 150 Meter Well.
S12-150R2, GW 1M, FOC 0.01, DIST 150M, R 0.00635 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
1.5024E+03
7.4166E+01
l.OOOOE+04
3.5669E+01
l.OOOOE+04
1.6321E+03
l.OOOOE+04
8.7687E+02
7.0125E-02
l.OOOOE+04
6.2055E+03
2.5680E+03
4.6745E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
195.9 %
214.9 %
0.0 %
4097.1 %
3897.4 %
11599.6 %
0.0 %
5000.2 %
0.0 %
20228.9 %
321.3 %
4900.7 %
4106.7 %
This case is the same as Case S11-150R2 (Table 65) with higher
soil organic content. Results are almost identical for all but DDT
which is retarded enough to benefit from greater dispersion. For most
other chemicals, the minimal recharge is the overriding determinant of
allowable sludge contaminant concentrations.
85
-------
Table 75.
The Effect of Minimal Depth to Groundwater and Increased Soil
Organic Matter in a Thick Aquifer at a 150 Meter Well.
S12-150T1, GW 1M, FOC 0.01, DIST 150M, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
2.5258E+01
9.8462E+00
l.OOOOE+04
5.3150E+02
2.5881E+01
l.OOOOE+04
1.7631E+00
4.8882E+02
1.6298E+03
l.OOOOE+04
8.0881E+02
7.0109E-02
l.OOOOE+04
2.3724E+03
9.3717E+01
2.3108E+00
% DIFFERENCE
5.6 %
4.3 %
0.0 %
4.7 %
9.9 %
0.0 %
107.5 %
95.4 %
11583.2 %
0.0 %
4604.3 %
0.0 %
20228.9 %
61.1 %
82.5 %
108.0 %
This case is similar to Case S12-150 (Table 72) with a thicker
aquifer for more vertical dispersion. The added depth for dilution
results in larger allowable sludge concentrations for most organics
arsenic and cadmium. The greatest increases are with the organics
other than those controlled by vapor considerations.
86
-------
Table 76.
The Effect of Minimal Depth to Groundwater and Increased
Soil Organic Matter in a Thin Aquifer at a 150 Meter Well.
S12-150T2, GW 1M, FOC 0.01, DIST 150M, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
1.4585E+01
6.6166E+00
2.8184E+03
4.9851E+02
2.4117E+01
1.0108E+03
2.8347E-01
8.3400E+01
1.6314E+03
l.OOOOE+04
5.9104E+02
7.0114E-02
l.OOOOE+04
5.7529E+02
1.7044E+01
3.7113E-01
% DIFFERENCE
-39.0 %
-29.9 %
-71.8 %
-1.8 %
2.4 %
-89.9 %
-66.6 %
-66.7 %
11594.6 %
0.0 %
3337.7 %
0.0 %
20228.9 %
-60.9 %
-66.8 %
-66.6 %
This case is similar to Case S12-150 (Table 72) with a thinner
aquifer. The latter condition restricts vertical dispersion and
results in much lower allowable sludge concentrations for all chemicals
except those that are driven by vapor considerations (BEHP, Chlordane,
and DMN) and Lindane where degradation overrides other factors.
87
-------
Table 77.
The Effect of Minimal Depth to Groundwater, Increased Soil
Organic Matter and Reduced Recharge in a Thick Aquifer
at a 150 Meter Well.
S12-150R1T1, GW 1M, FOC 0.01, DIST 150M, R 0.25M/Y, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
3.8315E+01
1.6888E+01
l.OOOOE+04
6.2480E+02
3.0829E+01
l.OOOOE+04
3.5262E+00
9.7664E+02
1.6298E+03
l.OOOOE+04
8.4103E+02
7.0109E-02
l.OOOOE+04
3.4944E+03
1.8743E+02
3.6391E+00
% DIFFERENCE
60.2 %
78.9 %
0.0 %
23.0 %
30.9 %
0.0 %
314.9 %
290.4 %
11583.2 %
0.0 %
4791.7 %
0.0 %
20228.9 %
137.2 %
265.0 %
227.5 %
This case is similar to Case S11-150R1T1 (Table 68) but has higher
soil organic content. The net effect is limited to DDT and Lindane
where retention in the unsaturated zone allows for more dispersion and
degradation, respectively. The effects for the greater retardation are
limited because of the extremely thin unsaturated zone.
88
-------
Table 78.
The Effect of Minimal Depth to Groundwater, Increased Soil Organic
Content and Reduced Recharge in a Thin Aquifer at a 150 Meter Well.
S12-150R1T2, GW 1M, FOC 0.01, DIST 150M, R 0.25M/Y, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
1.00aOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
1.6064E+01
7.1561E+00
4.2274E+03
5.3451E+02
2.6360E+01
4.5990E+03
5.6694E-01
1.6658E+02
1.6187E+03
l.OOOOE+04
6.9875E+02
7.0114E-02
l.OOOOE+04
1.0591E+03
3.4225E+01
6.2009E-01
% DIFFERENCE
-32.8 %
-24.2 %
-57.7 %
5.3 %
11.9 %
-54.0 %
-33.3 %
-33.4 %
11503.6 %
0.0 %
3964.2 %
0.0 %
20228.9 %
-28.1 %
-33.4 %
-44.2 %
This case is the same as Case S11-150R1T2 (Table 69) with a higher
soil organic content. The results are virtually identical except for
DDT and Lindane. These two chemicals are still sensitive to
unsaturated zone movement and, as such, have more dispersion and
degradation, respectively. The effects are limited because of the very
thin unsaturated zone over which they can occur.
89
-------
Table 79.
TKe Effect of Minimal Depth to Groundwater, Increased Soil Organic
Content and Minimal Recharge in a Thick Aquifer at a 150 Meter Well,
S12-150R2T1, GW 1M, FOC 0.01, DIST 150M, R 0.00635M/Y, AQ 78.6M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
5.8285E+03
l.OOOOE+04
6.9666E+01
l.OOOOE+04
1.6316E+03
l.OOOOE+04
8.7882E+02
7.0125E-02
l.OOOOE+04
6.4131E+03
4.6861E+03
9.1326E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
1869.2 %
24647.4 %
0.0 %
8097.4 %
3897.4 %
11596.1 %
0.0 %
5011.5 %
0.0 %
20228.9 %
335.4 %
9025.3 %
8118.7 %
This is the same case as Case S11-150R2T1 (Table 70) only there is
more soil organic content. Results are nearly identical between the
two because the minimal recharge dominates the affects by slowing time
of travel significantly.
90
-------
Table 80.
The Effect of Minimal Depth to Groundwater and Recharge, Increased
Soil Organic Matter in a Thin Aquifer at a 150 Meter Well.
S12-150R2T2, GW 1M, FOC 0.01, DIST 150M, R 0.00635M/Y, AQ 5.0M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3920E+01
9.4419E+00
l.OOOOE+04
5.0782E+02
2.3552E+01
l.OOOOE+04
8.4985E-01
2.5016E+02
1.3950E+01
l.OOOOE+04
1.7193E+01
7.0111E-02
4.9191E+01
1.4729E+03
5.1353E+01
1.1112E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
4.3751E+02
2.1325E+01
l.OOOOE+04
1.1861E+01
4.1690E+03
1.6187E+03
l.OOOOE+04
8.6838E+02
7.0114E-02
l.OOOOE+04
5.4842E+03
8.5562E+02
1.5513E+01
% DIFFERENCE
41706.0 %
105810.9 %
0.0 %
-13.8 %
-9.5 %
0.0 %
1295.7 %
1566.5 %
11503.6 %
0.0 %
4950.8 %
0.0 %
20228.9 %
272.3 %
1566.2 %
1296.1 %
This case is the same as Case S11-150R2T2 (Table 71) with higher
soil organic content. The results are identical with the exception of
DDT where the higher organic levels retard unsaturated movement
allowing for more dispersion. Hence, allowable sludge concentrations
are greater for DDT with the larger soil organic content.
91
-------
Table 81.
Base Case for 50 Meter Well.
B-50
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
t
4
9
1
4
4
1
5
2
2
3
1
4
4
2
4
5
AQUIFER
.960E-02
.OOOE-03
.260E+00
.900E-02
.570E-04
.390E+00
.OOOE-03
.990E-04
.420E-01
.020E-04
.OOOE-02
.740E-28
.480E-03
.490E-04
.980E-03
.OOOE-03
0
0
0
0
0
0
0
2
5
4
1
1
0
2
0
0
VAPOR
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.854E-11
.292E-03
.388E-04
.809E-04
.OOOE-04
.OOOE+00
.049E-04
.OOOE+00
.OOOE+00
1
4
1
1
1
3
2
0
0
0
0
0
0
0
0
0
0
BACKGRND
.OOOE-04
.OOOE-03
.OOOE-02
.OOOE-03
.OOOE-04
.700E-03
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
5
1
1
5
7
1
5
2
2
7
1
1
4
4
4
5
SUM
.OOOE-02
.OOOE-02
.270E+00
.OOOE-02
.570E-04
.393E+00
.OOOE-03
.990E-04
.473E-01
.408E-04
.018E-02
.OOOE-04
.480E-03
.539E-04
.980E-03
.OOOE-03
5
1
1
5
2
1
5
3
2
2
1
1
4
4
5
5
HEL
.OOOE-02
.OOOE-02
.300E+00
.OOOE-02
.OOOE-03
.750E+00
.OOOE-03
.OOOE-04
.480E-01
.100E-03
.020E-02
.OOOE-04
.OOOE-03
.540E-04
.OOOE-03
.OOOE-03
DRY WGHT
6.140E+00
2.747E+00
l.OOOE+04
2.394E+02
l.OOOE+04
l.OOOE+04
6.438E-01
2.259E+02
1.091E+01
l.OOOE+04
4.892E+00
2.196E-02
1.276E+01
9.387E+02
2.116E+01
8.416E-01
92
-------
Table 82.
Effects of Increasing Depth to Groundwater from 0 to 10 Meters
at a 50 Meter Well.
S7-50, GW 10M, FOC 0.0001, D 50M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
1.1660E+01
4.7769E+00
l.OOOOE+04
4.7031E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
5.1099E+02
l.OOOOE+04
1.2365E+02
2.1959E-02
3.9042E+02
9.3867E+02
2.1159E+01
8.4160E-01
% DIFFERENCE
89.9 %
73.9 %
0.0 %
96.5 %
0.0 %
0.0 %
0.0 %
0.0 %
4583.3 %
0.0 %
2427.5 %
0.0 %
2632.9 %
0.0 %
0.0 %
0.0 %
This case is similar to case S7-150 (Table 27) with the exposure
point closer to the source (50 meters as opposed to 150 meters). The
allowable sludge concentrations are generally less than those for the
150 meter case because there is less travel time over which dispersion
will occur. These effects are noted mostly for chemicals with short
release (pulse) times compared to travel times. They are not noted
where vapor considerations or unsaturated zone effects control risk.
In two cases, arsenic and DDT, the allowable concentrations are
greater compared to the base case because of the relative importance of
unsaturated transport versus saturated transport. Copper, mercury,
nickel, and chlordane were already at the maximum allowable sludge
concentrations of 10,000 mg/kg in the base case.
93
-------
Table 83.
Effects of Increased Depth to Groundwater (10 Meters)
and Increased Soil Organic Content at a 50 Meter Well.
S8-50, GW 10M, FOC 0.01, D 50M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
1.1603E+01
4.7770E+00
l.OOOOE+04
4.7053E+02
l.OOOOE+04
l.OOOOE+04
6.4448E-01
3.7044E+02
5.1125E+02
l.OOOOE+04
2.7256E+02
2.1958E-02
l.OOOOE+04
9.3897E+02
2.1160E+01
1.1873E+00
% DIFFERENCE
89.0 %
73.9 %
0.0 %
96.5 %
0.0 %
0.0 %
0.1 %
64.0 %
4585.6 %
0.0 %
5471.3 %
0.0 %
69898.6 %
0.0 %
0.0 %
41.1 %
This case is the same as S7-50 (Table 82) with a higher soil
organic content. The higher organic levels effect retention of highly
retarded contaminants and, therefore, this setting has higher allowable
sludge levels for B(A)P, DDT, and Toxaphene due to greater dispersion
and Lindane due to greater degradation. Other chemicals are not
effected because they have long release times which do not benefit from
the longitudinal dispersion provided by delayed transport in the
unsaturated zone. Copper, mercury, nickel, and chlordane were already
at the maximum allowable sludge level of 10,000 mg/kg.
94
-------
Table 84.
Effects of Increasing Depth to Groundwater from 0 to 5 Meters
at a 50 Meter Well.
S9-50, GW 5M, FOC 0.0001, D 50M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
8.4328E+00
3.2177E+00
l.OOOOE+04
3.4583E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
5.1073E+02
l.OOOOE+04
7.9469E+01
2.1959E-02
9.1326E+01
9.3867E+02
2.1159E+01
8.4160E-01
37.4 %
17.1 %
0.0 %
44.5 %
0.0 %
0.0 %
0.0 %
0.0 %
4580.9 %
0.0 %
1524.4 %
0.0 %
539.3 %
0.0 %
0.0 %
0.0 %
This case is similar to S7-50 (Table 82) but has only half the
depth to groundwater. As expected, the reduced travel time in the
unsaturated zone reduces the dispersion and degradation effects leading
to lower allowable sludge levels for chemicals where the release time
is short compared to the travel time. These include arsenic, cadmium,
lead, DDT, and Lindane. BEHP, chlordane, and DMN are unaffected
because their risk levels are driven by vapor considerations.
95
-------
Table 85.
Effects of Increased Depth to Groundwater from 0 to 5 Meters
and Increased Soil Organic Content at a 50 Meter Well.
S10-50, GW 5M, FOC 0.01, D 50M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
8.4437E+00
3.2488E+00
l.OOOOE+04
3.4600E+02
l.OOOOE+04
l.OOOOE+04
6.4448E-01
2.5295E+02
5.1126E+02
l.OOOOE+04
2.6935E+02
2.1964E-02
l.OOOOE+04
9.3955E+02
2.1160E+01
8.9385E-01
% DIFFERENCE
37.5 %
18.3 %
0.0 %
44.5 %
0.0 %
0.0 %
0.1 %
12.0 %
4585.7 %
0.0 %
5405.7 %
0.0 %
69898.6 %
0.1 %
0.0 %
6.2 %
This case is the same as S9-50 (Table 84) with a higher soil
organic content. As a result, the allowable sludge levels are
comparable except for those for B(A)P, DDT, Lindane, and Toxaphene.
These four chemicals sorb strongly to organic matter and, therefore,
move more slowly whe a there is more soil organic matter. Since they
have small release times compared to travel times, the outcome is more
dispersion which reduces groundwater concentrations. Other highly
retarded organics are not affected because they are driven by vapor
considerations (BEHP, Chlordane, and DMN) or because they have long
release times (PCB).
96
-------
Table 86.
Effects of Increased Depth to Groundwater from 0 to 1 Meter
at a 50 Meter Well.
Sll-50, GW 1M, FOC 0.0001, D 50M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2J959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
6.1889E+00
2.7644E+00
l.OOOOE+04
2.3547E+02
l.OOOOE+04
l.OOOOE+04
6.4448E-01
2.2597E+02
5.0862E+02
l.OOOOE+04
2.0857E+01
2.1964E-02
2.1803E+01
9.3955E+02
2.1160E+01
8.4645E-01
% DIFFERENCE
0.8 %
0.6 %
0.0 %
-1.6 %
0.0 %
0.0 %
0.1 %
0.0 %
4561.5 %
0.0 %
326.3 %
0.0 %
52.6 %
0.1 %
0.0 %
0.6 %
This case is like S9-50 (Table 84) with an even smaller
unsaturated zone. Conversely, it is like the base case with a minimal
unsaturated zone. The 1 meter of unsaturated soil sufficiently slows
down a few organics to affect allowable sludge concentrations. Namely,
BEHP is held up to the point that vapor transport dominates risk
considerations. DDT is slowed such that dispersion affects reduce its
peak groundwater concentrations and Lindane is held long enough for
degradation to become significant. The other chemicals either move
more rapidly or have too long a release time to benefit.
97
-------
Table 87.
Effects of Increasing Depth to Groundwater from 0 to 1 Meter
and Increasing Soil Organic Content from 0.0001 to 0.01
at a 50 Meter Well.
S12-50, GW 1M, FOC 0.0001, D BOM
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
6.1889E+00
2.7645E+00
l.OOOOE+04
2.3547E+02
l.OOOOE+04
l.OOOOE+04
6.4448E-01
2.2597E+02
5.1126E+02
l.OOOOE+04
2.4563E+02
2.1964E-02
l.OOOOE+04
9.3955E+02
2.1160E+01
8.4645E-01
% DIFFERENCE
0.8 %
0.6 %
0.0 %
-1.6 %
0.0 %
0.0 %
0.1 %
0.0 %
4585.7 %
0.0 %
4920.8 %
0.0 %
69898.6 %
0.1 %
0.0 %
0.6 %
This case is the same as Sll-50 (Table 86) except for a much
higher soil organic content. The net results are the same only the
effects are more pronounced so that allowable sludge concentrations are
even higher.
98
-------
Table 88.
Base Case for Well at 500 Meters.
B-500
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
i
4
8
3
1
3
8
4
3
2
1
9
0
4
4
5
5
AQUIFER
.950E-02
.960E-03
.870E-01
.030E-01
.460E-04
.540E-01
.990E-03
.OOOE-04
.470E-01
.650E-20
.730E-03
.OOOE+00
.OOOE-03
.280E-04
.OOOE-03
.OOOE-03
0.
0.
0.
0.
0.
0.
0.
2.
4.
2.
4.
1.
0.
2.
0.
0.
VAPOR
OOOE+00
OOOE+00
OOOE+00
OOOE+00
OOOE+00
OOOE+00
OOOE+00
083E-12
719E-04
420E-05
702E-04
OOOE-04
OOOE+00
565E-05
OOOE+00
OOOE+00
4
1
1
1
3
2
0
0
0
0
0
0
0
0
0
0
BACKGRND
.OOOE-04
.OOOE-03
.OOOE-02
.OOOE-03
.OOOE-04
.700E-03
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
4
9
3
1
6
8
4
3
2
2
1
1
4
4
5
5
SUM
.990E-02
.960E-03
.970E-01
.040E-01
.460E-04
.567E-01
.990E-03
.OOOE-04
.475E-01
.420E-05
.020E-02
.OOOE-04
.OOOE-03
.536E-04
.OOOE-03
.OOOE-03
5
1
1
5
2
1
5
3
2
2
1
1
4
4
5
5
HEL
.OOOE-02
.OOOE-02
.300E+00
.OOOE-02
.OOOE-03
.750E+00
.OOOE-03
.OOOE-04
.480E-01
.100E-03
.020E-02
.OOOE-04
.OOOE-03
.540E-04
.OOOE-03
.OOOE-03
DRY WGHT
1.058E+02
4.669E+01
l.OOOE+04
2.481E+03
l.OOOE+04
l.OOOE+04
1.159E+00
2.989E+02
1.764E+01
l.OOOE+04
2.306E+02
3.982E-01
1.173E+03
2.130E+03
1.304E+03
1.518E+00
99
-------
Table 89.
Effects of Increasing Depth to Groundwater from 0 to 10 Meters
at a 500 Meter Well.
S7-500, GW 10M, FOC 0.0001, DIST 500M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
SENSITIVITY
CONC
(MG/L)
5.00E-02
l.OOE-02
3.87E-01
1.03E-01
3.46E-04
8.54E-01
4.99E-03
3.00E-04
2.47E-01
1.65E-20
9.73E-03
O.OOE+00
4.00E-03
4.28E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
1.06E+02
4.67E+01
l.OOE+04
2.48E+03
l.OOE+04
l.OOE+04
1.16E+00
2.99E+02
1.76E+01
l.OOE+04
2.31E+02
3.98E-01
1.17E+03
2.13E+03
1.30E+03
1.52E+00
1.07E+02
4.76E+01
l.OOE+04
3.65E+03
l.OOE+04
l.OOE+04
1.16E+00
2.99E+02
9.20E+03
l.OOE+04
3.67E+03
3.98E-01
l.OOE+04
2.13E+03
1.30E+03
1.52E+00
% DIFFERENCE
1.0 %
1.9 %
0.0 %
47.2 %
0.0 %
0.0 %
0.0 %
0.0 %
52059.9 %
0.0 %
1490.6 %
0.0 %
752.5 %
0.0 %
0.0 %
0.0 %
This case demonstrates that as the monitoring point gets further
from the source, changes in the unsaturated zone depth become less
significant for most chemicals. Only lead, BEHP, DDT, and Lindane
benefit significantly from the added unsaturated zone transport time.
These are some of the more retarded contaminants with sufficiently
short release periods that they benefit from added dispersion. Lindane
also benefits from any delay because of the added degradation. Copper,
mercury, nickel, and chlordane were already at the maximum allowable
sludge concentration of 10,000 mg/kg in the base case.
100
-------
Table 90.
Effects of Increasing Depth to Groundwater from 0 to 10 Meters
and Increasing Soil Organic Content from 0.0001 to 0.01
at a 500 Meter Well.
S8-500, GW=10M, FOC=0.01, DIST=500M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
SENSITIVITY
CONC
(MG/L)
5.00E-02
l.OOE-02
3.87E-01
1.03E-01
3.46E-04
8.54E-01
4.99E-03
3.00E-04
2.47E-01
1.65E-20
9.73E-03
O.OOE+00
4.00E-03
4.28E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
1.06E+02
4.67E+01
l.OOE+04
2.48E+03
l.OOE+04
l.OOE+04
1.16E+00
2.99E+02
1.76E+01
l.OOE+04
2.31E+02
3.98E-01
1.17E+03
2.13E+03
1.30E+03
1.52E+00
1.07E+02
4.75E+01
l.OOE+04
3.65E+03
l.OOE+04
l.OOE+04
1.16E+00
4.90E+02
9.27E+03
l.OOE+04
4.99E+03
3.98E-01
l.OOE+04
2.13E+03
1.30E+03
2.15E+00
% DIFFERENCE
1.0 %
1.8 %
0.0 %
47.1 %
0.0 %
0.0 %
0.5 %
64.0 %
52445.4 %
0.0 %
2061.8 %
0.0 %
752.5 %
0.0 %
0.0 %
41.7 %
This case is the same as S7-500 (Table 89) with a much higher
level of organic matter in the soil. As expected, the major impact
occurs with the organics where the higher retardation enhances
dispersion effects. Among the organics, only chlordane and DMN remain
unaffected. This results from chlordane's already having reached the
maximum level of 10,000 mg/kg and DMN's being driven by vapor
considerations.
101
-------
Table 91.
Effects of Increasing Depth to Groundwater from 0 to 5 Meters
at a 500 Meter Well.
S9-500, GW=5M, FOC=0.0001, DIST=500M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
SENSITIVITY
CONC
(MG/L)
5.00E-02
l.OOE-02
3.87E-01
1.03E-01
3.46E-04
8.54E-01
4.99E-03
3.00E-04
2.47E-01
1.65E-20
9.73E-03
O.OOE+00
4.00E-03
4.28E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
1.06E+02
4.67E+01
l.OOE+04
2.48E+03
l.OOE+04
l.OOE+04
1.16E+00
2.99E+02
1.76E+01
l.OOE+04
2.31E+02
3.-98E-01
1.17E+03
2.13E+03
1.30E+03
1.52E+00
1.07E+02
4.70E+01
l.OOE+04
3.11E+03
l.OOE+04
l.OOE+04
1.16E+00
2.99E+02
9.14E+03
l.OOE+04
2.89E+03
3.98E-01
7.51E+03
2.13E+03
1.30E+03
1.52E+00
% DIFFERENCE
1.0 %
0.7 %
0.0 %
25.5 %
0.0 %
0.0 %
0.0 %
0.0 %
51697.1 %
0.0 %
1155.0 %
0.0 %
540.4 %
0.0 %
0.0 %
0.0 %
This case is the same as S7-500 (Table 89) but with half the depth
to ground water. The effects are the same but less pronounced since
the shallower depth to groundwater leads to less time for degradation
(Lindane) and less dispersion in the unsaturated zone.
102
-------
Table 92.
Effects of Increasing Depth to Groundwater from 0 to 5 Meters
and Increasing Soil Organic Content from 0.0001 to 0.01
at a 500 Meter Well.
S10-500, GW=5M, FOC=0.01, DIST=500M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
l.OOE-03
3.87E-01
1.03E-01
3.46E-04
8.54E-01
4.99E-03
3.00E-04
2.47E-01
1.65E-20
9.73E-03
O.OOE+00
4.00E-03
4.28E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
1.06E+02
4.67E+01
l.OOE+04
2.48E+03
l.OOE+04
l.OOE+04
1.16E+00
2.99E+02
1.76E+01
l.OOE+04
2.31E+02
3.98E-01
1.17E+03
2.13E-t-03
1.30E+03
1.52E+00
1.07E+02
4.70E+01
l.OOE+04
3.11E+03
l.OOE+04
l.OOE+04
1.16E+00
3.35E+02
9.27E+03
l.OOE+04
4.97E+03
3.98E-01
l.OOE+04
2.13E+03
1.30E+03
1.61E+00
% DIFFERENCE
1.0 %
0.8 %
0.0 %
25.4 %
0.0 %
0.0 %
0.3 %
12.0 %
52439.7 %
0.0 %
2053.9 %
0.0 %
752.5 %
0.0 %
0.0 %
5.9 %
This case is the same as S8-500 (Table 90) but with half the depth
to ground water. As expected, the effect is seen on chemicals where
unsaturated zone considerations are significant. Both lead and B(A)P
allowable sludge levels reflect the shorter unsaturated zone travel
time.
103
-------
Table 93.
Effects of Increasing Depth to Groundwater from 0 to 1 Meter
at a 500 Meter Well.
Sll-500, GW-1M, FOC-0.0001, DIST=500M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
l.OOE-03
3.87E-01
1.03E-01
3.46E-04
8.54E-01
4.99E-03
3.00E-04
2.47E-01
1.65E-20
9.73E-03
O.OOE+00
4.00E-03
4.28E-04
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
1.06E+02
4.67E+01
l.OOE+04
2.48E+03
l.OOE+04
l.OOE+04
1.16E+00
2.99E+02
1.76E+01
l.OOE+04
2.31E+02
3.98E-01
1.17E+03
2.13E+03
1.30E+03
1.52E+00
1.07E+02
4.70E+01
l.OOE+04
1.96E+03
l.OOE
l.OOE+04
1.16E+00
2.99E+02
8.65E+03
l.OOE+04
1.08E+03
3.98E-01
1.79E+03
2.13E+03
1.30E+03
1.52E+00
% DIFFERENCE
1.0 %
0.7 %
0.0 %
-21.2 %
0.0 %
0.0 %
0.0 %
0.0 %
48907.9 %
0.0 %
370.1 %
0.0 %
52.5 %
0.0 %
0.0 %
0.0 %
This case is the same as S10-500 (Table 92) with an even shallower
depth to groundwater. As expected, the effects are in the chemicals
that gain from dispersion and retardation in the unsaturated zone
because of small release times compared to travel times or degradation.
BEHP gains the most because of its very strong interactions with soil.
104
-------
Table 94.
Effects of Increasing Depth to Groundwater from 0 to 1 Meter
and Increasing Soil Organic Content from 0.0001 to 0.01
at a 500 Meter Well.
S12-500, GW-1M, FOC-0.01, DIST=500M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.00E-02
l.OOE-02
3.87E-01
1.03E-01
3.46E-04
8.54E-01
4.99E-03
3.00E-04
2.47E-01
1.65E-20
9.73E-03
O.OOE+00
4.00E-03
4.28E-
5.00E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
1.06E+02
4.67E+01
l.OOE+04
2.48E+03
l.OOE+04
l.OOE+04
1.16E+00
2.99E+02
1.76E+01
l.OOE+04
2.31E+02
3.98E-01
1.17E+03
2.13E+03
1.30E+03
1.52E+00
1.07E+02
4.70E+01
l.OOE+04
1.96E+03
l.OOE+04
l.OOE+04
1.16E+00
2.99E+02
9.26E+03
l.OOE+04
4.83E+03
3.98E-01
l.OOE+04
2.13E+03
1.30E+03
1.52E+00
% DIFFERENCE
1.0 %
0.8 %
0.0 %
-21.1 %
0.0 %
0.0 %
0.3 %
0.0 %
52405.7 %
0.0 %
1993.2 %
0.0 %
752.5 %
0.0 %
0.0 %
-0.1 %
This case is the same as S10-500 (Table 92) but with a greatly
reduced depth to groundwater. As expected, the results are similar
between the two except for lead, which reflects some of the difficulty
associated with the back calculation for allowable sludge levels. All
other chemicals' risks are driven by the saturated zone transport and,
therefore, do not respond to the changes in the depth to groundwater.
105
-------
Table 95.
Base Case for Well at 1000 Meters.
B-1000
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
AQUIFER
4
8
2
4
2
5
4
3
2
0
8
0
2
4
2
5
.940E-02
.960E-03
.400E-01
.900E-02
.290E-04
.130.E-01
.990E-03
.010E-04
.480E-01
.OOOE+00
.020E-03
.OOOE+00
.560E-03
.410E-04
.890E-03
.OOOE-03
VAPOR
0
0
0
0
0
0
0
1
2
8
2
1
0
1
0
0
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.060E-12
.517E-04
.127E-06
.177E-03
.OOOE-04
.OOOE+00
.341E-05
.OOOE+00
.OOOE+00
BACKGRND
4
1
1
1
3
2
0
0
0
0
0
0
0
0
0
0
.OOOE-04
.OOOE-03
.OOOE-02
.OOOE-03
.OOOE-04
.700E-03
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
.OOOE+00
4
9
2
5
5
5
4
3
2
8
1
1
2
4
2
5
SUM
.980E-02
.960E-03
.500E-01
.OOOE-02
.290E-04
.157E-01
.990E-03
.010E-04
.483E-01
.127E-06
.020E-02
.OOOE-04
.560E-03
.544E-04
.890E-03
.OOOE-03
5
1
1
5
2
1
5
3
2
2
1
1
4
4
5
5
HEL
.OOOE-02
.OOOE-02
.300E+00
.OOOE-02
.OOOE-03
.750E+00
.OOOE-03
.OOOE-04
.480E-01
.100E-03
.020E-02
.OOOE-04
.OOOE-03
.540E-04
.OOOE-03
.OOOE-03
DRY WGHT
2.372E+02
1.042E+02
l.OOOE+04
6.354E+03
l.OOOE+04
l.OOOE+04
1.750E+00
4.514E+02
2.798E+01
l.OOOE+04
3.179E+03
1.186E+00
l.OOOE+04
3.313E+03
l.OOOE+04
2.293E+00
106
-------
Table 96.
Effects of Increasing Depth to Groundwater from 0 to 10 Meters
at a 1000 Meter Well.
S7-1000, GW=10M, FOC-0.0001, DIST=1000M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
BASE CASE
CONG'S
(MG/L)
4.94E-02
l.OOE-03
2.40E-01
4.90E-02
2.29E-04
5.13E-01
4.99E-03
3.01E-04
2.48E-01
O.OOE+00
8.02E-03
O.OOE+00
2.56E-03
4.41E-04
2.89E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.37E+02
1.04E+02
l.OOE+04
6.35E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
2.80E+01
l.OOE+04
3.18E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
2.38E+02
1.04E+02
l.OOE+04
7.68E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
l.OOE+04
l.OOE+04
l.OOE+04
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
% DIFFERENCE
0.1 %
0.1 %
0.0 %
20.9 %
0.0 %
0.0 %
0.0 %
0.0 %
35639.8 %
0.0 %
214.6 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
The greatly increased distance between source and exposure point
minimizes the importance of the unsaturated zone. Only three chemicals
benefit from the increased depth; lead, BEHP, and DDT. All three are
slow moving in the unsaturated zone. BEHP is sufficiently retarded for
the vapor pathway to become overriding. Lead and DDT have sufficiently
short release times that the longer travel time in the unsaturated zone
results in more dispersion in the aquifer.
107
-------
Table 97.
Effects of Increasing Depth to Groundwater from 0 to 10 Meters
and Increasing Soil Organic Content from 0.0001 to 0.01
at a 1000 Meter Well.
S8-1000, GW=10M, FOC=0.01, DIST=1000M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
4.94E-02
l.OOE-03
2.40E-01
4.90E-02
2.29E-04
5.13E-01
4.99E-03
3.01E-04
2.48E-01
O.OOE+00
8.02E-03
O.OOE+00
2.56E-03
4.41E-04
2.89E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.37E+02
1.04E+02
l.OOE+04
6.35E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
2.80E+01
l.OOE+04
3.18E+03
M9E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
2.38E+02
1.04E+02
l.OOE+04
7.68E+03
l.OOE+04
l.OOE+04
1.76E+00
7.39E+02
l.OOE+04
l.OOE+04
l.OOE+04
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
3.25E+00
% DIFFERENCE
0.1 %
0.1 %
0.0 %
20.8 %
0.0 %
0.0 %
0.3 %
63.7 %
35639.8 %
0.0 %
214.6 %
0.0 %
0.0 %
0.0 %
0.0 %
41.7 %
This case is the same as S7-1000 (Table 96) except for the higher
soil organic content. The greater organic levels slow down unsaturated
transport even further. The effect is to delay organic chemicals
sufficiently that B(A)P and toxaphene benefit from additional
dispersion as the lead and DDT had already. In essence, the higher
organic content has raised the relative importance of the unsaturated
zone vis a vis the saturated transport for B(A)P and toxaphene.
108
-------
Table 98.
Effects of Increasing Depth to Groundwater from 0 to 15 Meters
at a 1000 Meter Well.
S9-1000, GW=5M, FOC-0.0001, DIST=1000M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
4.94E-02
l.OOE-03
2.40E-01
4.90E-02
2.29E-04
5.13E-01
4.99E-03
3.01E-04
2.48E-01
O.OOE+00
8.02E-03
O.OOE+00
2.56E-03
4.41E-04
2.89E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.37E+02
1.04E+02
l.OOE+04
6.35E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
2.80E+01
l.OOE+04
3.18E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
2.38E+02
1.04E+02
l.OOE+04
7.13E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
l.OOE+04
l.OOE+04
l.OOE+04
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
% DIFFERENCE
0.2 %
0.2 %
0.0 %
12.2 %
0.0 %
0.0 %
0.0 %
0.0 %
35639.8 %
0.0 %
214.6 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
This case is the same as S7-1000 (Table 96) but with half the
depth to groundwater. The results are almost identical except that the
allowable levels for lead are decreased due to less unsaturated zone
travel time and, hence, less dispersion. The effects on BEHP and DDT
are unchanged because the maximum impact has already been reached and
is not affected by further delays in unsaturated transport.
109
-------
Table 99.
Effects of Increasing Depth to Groundwater from 0 to 5 Meters
and Increasing Soil Organic Content from 0.0001 to 0.01
at a 1000 Meter Well.
S10-1000, GW=5M, FOC-0.01, DIST=1000M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
4.94E-02
l.OOE-03
2.40E-01
4.90E-02
2.29E-04
5.13E-01
4.99E-03
3.01E-04
2.48E-01
O.OOE+00
8.02E-03
O.OOE+00
2.56E-03
4.41E-04
2.89E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.37E+02
1.04E+02
l.OOE+04
6.35E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
2.80E+01
l.OOE+04
3.18E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
2.38E+02
1.04E+02
l.OOE+04
7.12E+03
l.OOE+04
l.OOE+04
1.76E+00
5.05E+02
l.OOE+04
l.OOE+04
l.OOE+04
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.43E+00
% DIFFERENCE
0.2 %
0.1 %
0.0 %
12.1 %
0.0 %
0.0 %
0.3 %
11.8 %
35639.8 %
0.0 %
214.6 %
0.0 %
0.0 %
0.0 %
0.0 %
5.9 %
This case is the same as S9-1000 (Table 98) except for a much
higher soil organic content. Once again, the saturated zone transport
considerations are overriding here for all but a few chemicals. For
three of these, lead, BEHP, and DDT, the effect of the unsaturated zone
is realized with a 5 meter depth and remains virtually unchanged at
greater depths to groundwater. B(A)P and toxaphene have higher
allowable sludge concentrations because the larger organic fraction
delays transport enough to benefit from added dispersion.
110
-------
Table 100.
Effects of Increasing Depth to Groundwater from 0 to 1 Meter
at a 1000 Meter Well.
Sll-1000, GW=1M, FOC=0.0001, DIST=1000M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
4.94E-02
l.OOE-03
2.40E-01
4.90E-02
2.29E-04
5.13E-01
4.99E-03
3.01E-04
2.48E-01
O.OOE+00
8.02E-03
O.OOE+00
2.56E-03
4.41E-04
2.89E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.37E+02
1.04E+02
l.OOE+04
6.35E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
2.80E+01
l.OOE+04
3.18E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
2.36E+02
1.04E+02
l.OOE+04
6.36E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
l.OOE+04
l.OOE+04
8.22E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
% DIFFERENCE
-0.5 %
0.1 %
0.0 %
0.1 %
0.0 %
0.0 %
0.0 %
0.0 %
35639.8 %
0.0 %
158.6 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
This case is the same as S9-1000 (Table 98) but has an even
shallower unsaturated zone. Once again, the effect is limited to a few
organics where delayed transport is of significance. One of these is
BEHP which becomes a vapor hazard because of the slow unsaturated zone
transport velocity. The other is DDT which undergoes dispersion and
dilution because the release time is short compared to the travel time.
Ill
-------
Table 101.
Effects of Increasing Depth to Groundwater from 0 to 1 Meter
and Increasing Soil Organic Content from 0.0001 to 0.01
at a 1000 Meter Well.
S12-1000, GW=1M, FOO0.01, DIST=1000M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
4.94E-02
T.OOE-03
2.40E-01
4.90E-02
2.29E-04
5.13E-01
4.99E-03
3.01E-04
2.48E-01
O.OOE+00
8.02E-03
O.OOE+00
2.56E-03
4.41E-04
2.89E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.37E+02
1.04E+02
l.OOE+04
6.35E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
2.80E+01
l.OOE+04
3.18E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
2.37E+02
1.04E+02
l.OOE+04
6.36E+03
l.OOE+04
l.OOE+04
1.76E+00
4.51E+02
l.OOE+04
l.OOE+04
l.OOE+04
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
% DIFFERENCE
-0.3 %
0.0 %
0.0 %
0.1 %
0.0 %
0.0 %
0.3 %
-0.2 %
35639.8 %
0.0 %
214.6 %
0.0 %
0.0 %
0.0 %
0.0 %
-0.1 %
This case is the same as Sll-1000 (Table 100) only the soil
organic content is higher and, therefore, retains organic contaminants
longer. The results are virtually identical with the exception of DDT.
DDT has a higher allowable sludge concentration for this case because
the slower unsaturated zone transport results in greater dispersion.
For all other chemicals the unsaturated depth is too thin to impact
final concentrations in any substantial way.
112
-------
Table 102.
Effects of Reducing Recharge from 0.5 to 0.25 m/y
for a Well at 50 Meters.
S13-50, RECHARGE = 0.25 M/Y, DIST = 50 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
6.2821E+00
2.8324E+00
l.OOOOE+04
2.3366E+02
l.OOOOE+04
l.OOOOE+04
1.2877E+00
4.5211E+02
2.1383E+01
l.OOOOE+04
9.5722E+00
2.1960E-02
2.8535E+01
1.2920E+03
4.2442E+01
1.6835E+00
2.3 %
3.1 %
0.0 %
-2.4 %
0.0 %
0.0 %
100.0 %
100.1 %
96.0 %
0.0 %
95.7 %
0.0 %
99.7 %
37.6 %
100.6 %
100.0 %
This case reflects the impacts of reduced recharge on the movement
of chemicals. Mechanistically speaking, the smaller amount of recharge
extends the release time (takes longer to dissolve out the inventory of
chemical) and leads to greater levels of dilution since the flux is
reduced.
The effects of reduced flux are not seen with the inorganics
because their aquifer concentrations are determined by solubility
constraints. Hence, all of the chemical brought down with higher
recharge levels was not solubilized. In fact, the amount solubilized
is less than one half and hence, the 100% change. Chlordane is
unaffected because it was already at the 10,000 mg/kg maximum.
Degradation dominates dilution effects and so is unchanged by the lower
recharge.
113
-------
Table 103.
The Effect of Minimal Recharge at a 50 Meter Well.
S14-50, RECHARGE = 0.00635 M/Y, DIST = 50 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
2.5446E+02
l.OOOOE+04
l.OOOOE+04
3.2193E+01
l.OOOOE+04
2.6096E+02
l.OOOOE+04
1.3070E+02
2.1960E-02
7.1338E+02
2.0300E+03
1.0611E+03
4.2088E+01
% DIFFERENCE
162777.1 %
363920.2 %
0.0 %
6.3 %
0.0 %
0.0 %
4900.8 %
4326.7 %
2291.7 %
0.0 %
2571.6 %
0.0 %
4893.6 %
116.3 %
4914.9 %
4901.0 %
This case reflects the effects of drastic reductions in recharge.
The greatly restricted flux of contaminant is subject to dispersion and
dilution in the aquifer. The only chemicals not effected are those
already at the maximum allowable sludge concentration of 10,000 mg/kg
(Copper, Mercury, and Nickel) and the chemicals with vapor driver risk
such as Chlordane and DMN. The solubility constraints are still
controlling for lead, but not for soluble Arsenic and Chlordane.
Hence, the big increases in allowable sludge levels for the latter two
inorganics. Most organics not at maximum allowable sludge levels
reflect a change of 4000% to 5000% reflecting the flux change due to
cutting recharge from 0.5 to 0.00635 m/yr.
114
-------
Table 104.
The Effect of Decreasing Recharge from 0.5 to 0.25 M/Y
at a 150 Meter Well
S13-150, RECHARGE = 0.25 M/Y, DIST = 150 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
2.3692E+01
9.4591E+00
l.OOOOE+04
5.0000E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3949E+01
l.OOOOE+04
1.7187E+01
7.0109E-02
4.9262E+01
1.4718E+03
5.1357E+01
1.1132E+00
3.6141E+01
1.6279E+01
l.OOOOE+04
4.9116E+02
l.OOOOE+04
l.OOOOE+04
1.6997E+00
5.0033E+02
2.7664E+01
l.OOOOE+04
2.3364E+01
7.0109E-02
9.7019E+01
2.4085E+03
1.0271E+02
1.8619E+00
52.5 %
72.1 %
0.0 %
1.8 %
0.0 %
0.0 %
100.0 %
100.1 %
98.3 %
0.0 %
35.9 %
0.0 %
96.9 %
63.6 %
100.0 %
67.3 %
The case illustrates the effect of reducing recharge when the
exposure point is distant from the source. It is analogous to case
S13-50 (Table 102) but with a longer travel path in the unsaturated
zone. The same chemicals are impacted in both cases, but the impacts
are greater for this case where the distance is larger. This is
because the longer distance makes the travel time greater relative to
the release time which leaves more room for dispersion to reduce peak
heights, hence, the longer travel distance accommodates larger
allowable sludge concentrations, just as the base case at 150 meters
has larger allowable sludge levels than the base case at 50 meters.
Copper, Mercury, Nickel, and Chlordane were already at the maximum
allowable sludge concentration of 10,000 mg/kg in the base case.
115
-------
Table 105.
The Effects of Decreasing Recharge from 0.5 to 0.00635 M/Y
at a 150 Meter Well
S14-150, RECHARGE = 0.00635 M/Y, DIST = 150 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3692E+01
9.4591E+00
l.OOOOE+04
5.0000E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3949E+01
l.OOOOE+04
1.7187E+01
7.0109E-02
4.9262E+01
1.4718E+03
5.1357E+01
1.1132E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
1.0560E+03
l.OOOOE+04
l.OOOOE+04
3.5533E+01
l.OOOOE+04
4.3248E+02
l.OOOOE+04
3.5679E+02
7.0112E-02
2.4599E+03
6.2034E+03
2.5630E+03
4.6558E+01
% DIFFERENCE
42108.3 %
105618.3 %
0.0 %
111.2 %
0.0 %
0.0 %
4081.2 %
3898.9 %
3000.4 %
0.0 %
1975.9 %
0.0 %
4893.5 %
321.5 %
4890.6 %
4082.4 %
This case illustrates the effects of a drastic reduction of
recharge. It resembles case S14-50 (Table 103) but has a longer travel
distance in the saturated zone. The same chemicals are affected, but
the net effect compared to the base case is of a lower magnitude. This
is because the extremely small amount of recharge predominates as the
determinant of exposure levels rather than the saturated travel
distance. The allowable concentrations between the two cases are
similar, but because the base case allowable levels are greater for the
150 meter travel distance, the percentage changes are smaller. When
compared to S13-150 (Table 104) the allowable levels are dramatically
higher reflecting the greatly increased dilution for the small amount
of recharge in the system. Copper, Mercury, Nickel, and Chlordane were
already at the maximum sludge concentrations of 10,000 mg/kg in the
case.
116
-------
Table 106.
The Effect of Reduced Recharge for a 500 Meter Well.
S13-500, 500 M BASE CASE BUT WITH R = 0.25 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
1.0584E+02
4.6687E+01
l.OOOOE+04
2.0969E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7638E+01
l.OOOOE+04
2.3061E+02
3.9816E-01
8.7968E+02
2.1299E+03
1.3035E+03
1.5178E+00
1.9913E+02
7.4517E+01
l.OOOOE+04
2.3956E+03
l.OOOOE+04
l.OOOOE+04
2.3174E+00
5.9778E+02
3.8197E+01
l.OOOOE+04
4.4047E+02
3.9816E-01
1.7594E+03
4.0350E+03
2.6070E+03
3.0356E+00
88.1 %
59.6 %
0.0 %
14.2 %
0.0 %
0.0 %
100.0 %
100.0 %
116.6 %
0.0 %
91.0 %
0.0 %
100.0 %
89.4 %
100.0 %
100.0 %
The case illustrates the effect of reducing recharge when the
exposure point is distant from the source. It is analogous to case
S13-50 (Table 102) but with a much longer travel path in the
unsaturated zone. The same chemicals are impacted in both cases, but
the impacts are greater for this case where the distance is larger.
This is because the longer distance makes the travel time greater
relative to the release time which leaves more room for dispersion to
reduce peak heights, hence, the longer travel distance accommodates
larger allowable sludge concentrations, just as the base case at 500
meters has larger allowable sludge levels than the base case at 50
meters. Copper, Mercury, Nickel, and Chlordane were already at the
maximum allowable sludge concentration of 10,000 mg/kg in the base
case.
117
-------
Table 107.
The Effect of Minimal Recharge at a 500 Meter Well.
S14-500, 500 M BASE CASE BUT WITH R = 0.00635 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
1.0584E+02
4.6687E+01
l.OOOOE+04
2.0969E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7638E+01
l.OOOOE+04
2.3061E+02
3.9816E-01
8.7968E+02
2.1299E+03
1.3035E+03
1.5178E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
6.8390E+03
l.OOOOE+04
l.OOOOE+04
4.2443E+01
l.OOOOE+04
6.5232E+02
l.OOOOE+04
3.7655E+03
3.9816E-01
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
5.5597E+01
% DIFFERENCE
9348.2 %
21319.2 %
0.0 %
226.1 %
0.0 %
0.0 %
3563.0 %
3245.7 %
3598.4 %
0.0 %
1532.8 %
0.0 %
1036.8 %
369.5 %
667.2 %
3563.0 %
This case illustrates the effects of a drastic reduction of
recharge. It resembles case S14-50 (Table 103) but has a longer travel
distance in the saturated zone. The same chemicals are affected, but
the net effect compared to the base case is of a lower magnitude. This
is because the extremely small amount of recharge predominates as the
determinant of exposure levels rather than the saturated travel
distance. The allowable concentrations between the two cases are
similar, but because the base case allowable levels are greater for the
500 meter travel distance, the percentage changes are smaller. When
compared to S13-500 (Table 106) the allowable levels are dramatically
higher reflecting the greatly increased dilution for the small amount
of recharge in the system. Copper, Mercury, Nickel, and Chlordane were
already at the maximum sludge concentrations of 10,000 mg/kg in the
case.
118
-------
Table 108.
The Effect of Reduced Recharge at a 1000 Meter Well.
S13-1000, 1000 M BASE CASE BUT WITH R = 0.25 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
2.3709E+02
1.0423E+02
l.OOOOE+04
6.3796E+03
l.OOOOE+04
l.OOOOE+04
1.7503E+00
4.5136E+02
2.7927E+01
l.OOOOE+04
3.1791E+03
1.1857E+00
l.OOOOE+04
3.3130E+03
l.OOOOE+04
2.2927E+00
4.5922E+02
2.1568E+02
l.OOOOE+04
7.3340E+03
l.OOOOE+04
l.OOOOE+04
3.5006E+00
9.0118E+02
4.8743E+01
l.OOOOE+04
5.2431E+03
1.1857E+00
l.OOOOE+04
6.4324E+03
l.OOOOE+04
4.5855E+00
93.7 %
106.9 %
0.0 %
15.0 %
0.0 %
0.0 %
100.0 %
99.7 %
74.5 %
0.0 %
64.9 %
0.0 %
0.0 %
94.2 %
0.0 %
100.0 %
This case is the same as case S13-500 (Table 106) with a larger
distance between the source and the exposure point. The same chemicals
are affected at about the same order of magnitude. However, the
overall effect is greater in this case because the longer saturated
zone travel path increases the travel time to release time ratio
providing more opportunity for dispersion to reduce peak heights.
119
-------
Table 109.
The Effect of Minimal Recharge at a 1000 Meter Well.
S14-1000, 1000 M BASE CASE BUT WITH R = 0.00635 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3709E+02
1.0423E+02
l.OOOOE+04
6.3796E+03
l.OOOOE+04
l.OOOOE+04
1.7503E+00
4.5136E+02
2.7927E+01
l.OOOOE+04
3.1791E+03
1.1857E+00
l.OOOOE+04
3.3130E+03
l.OOOOE+04
2.2927E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
6.4113E+01
l.OOOOE+04
1.0239E+03
l.OOOOE+04
l.OOOOE+04
1.1857E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
8.3983E+01
% DIFFERENCE
4117.8 %
9494.2 %
0.0 %
56.7 %
0.0 %
0.0 %
3563.0 %
2115.5 %
3566.3 %
0.0 %
214.6 %
0.0 %
0.0 %
201.8 %
0.0 %
3563.1 %
This case is the same as S14-500 (Table 107) with a greater
distance between the source and point of exposure. The allowable
sludge concentrations are comparable between the two because the
dispersion and dilution associated with the distance is large enough to
predominate risks and the maximum level in sludge of 10^ is reached.
Because the base case for 1000 meters is higher than for 500 meters,
the percentage increase over the base case is smaller (i.e., the
numerator is the same but the denominator is larger).
120
-------
Table 110.
The Effect of Higher Groundwater Velocity
at a 50 Meter Well.
S15-50, GW VEL 1000 M/Y, DIST 50 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
2.3461E+02
l.OOOOE+04
l.OOOOE+04
6.4376E+00
2.2666E+03
8.8013E+01
7.5610E+03
2.2275E+01
2.1960E-02
5.8132E+01
1.8540E+03
1.0372E+02
8.4160E+00
% DIFFERENCE
162777.1 %
363920.2 %
0.0 %
-2.0 %
0.0 %
0.0 %
900.0 %
903.4 %
706.6 %
-24.4 %
355.3 %
0.0 %
306.9 %
97.5 %
390.2 %
900.0 %
This case illustrates the effect of increasing aquifer velocity.
In essence, the higher velocity means more water passes under the site
in a year. Since the flux remains constant with the set recharge,the
higher velocity translates to greater dilution potential and hence,
higher allowable sludge concentrations. No effect is seen for
geochemically controlled contaminants which are already at maximum
sludge levels (Copper, Mercury, and Nickel) or for DMN whose sludge
level is determined by vapor considerations.
121
-------
Table 111.
The Effect of Lower Velocity at a 50 Meter Well.
S16-50, GW VEL 10 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
5.9943E+00
2.7471E+00
l.OOOOE+04
2.3414E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
1.7754E+02
2.1959E-02
1.8938E+03
9.3867E+02
2.1287E+03
8.4160E-01
% DIFFERENCE
-2.4 %
0.0 %
0.0 %
-2.2 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
3529.0 %
0.0 %
13156.3 %
0.0 %
9960.5 %
0.0 %
This case illustrates the effect of a lower groundwater velocity
and, hence, less water is available each year to receive and mix with
the recharge. The net effect is less dilution potential and,
therefore, lower allowable sludge levels. The major effect is noted
for those chemicals. For Lindane, DDT, and TCE, the velocity creates
longer travel times over which more degradation occurs. Therefore, the
allowable sludge levels are higher. Allowable sludge concentrations
also increase for DDT and TCE. Two other chemicals, Chlordane and DDT
also undergo degradation, but their other risks are determined by vapor
considerations at this distance.
122
-------
Table 112.
The Effect of Minimal Groundwater Velocity
at a 50 Meter Well.
S17-50, GW VEL 1 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
6.2593E+00
3.0775E+00
l.OOOOE+04
2.4620E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
2.7593E+02
2.1959E-02
l.OOOOE+04
9.3867E+02
l.OOOOE+04
8.4160E-01
% DIFFERENCE
1.9 %
12.0 %
0.0 %
2.8 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
5540.2 %
0.0 %
69898.6 %
0.0 %
47161.2 %
0.0 %
This case is analogous to S16-50 (Table 111) with an even smaller
groundwater velocity. As a consequence, the degradable organics have
longer to undergo degradation. See discussion in Table 111. The
slight change in Cadmium reflects the difficulty in matching sludge
values exactly with the back calculation method.
123
-------
Table 113.
The Effect of Higher Velocity Groundwater
at a 150 Meter Well.
S15-150, GW VEL 1000 M/Y, DIST = 150 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.QOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3692E+01
9.4591E+00
l.OOOOE+04
5.0000E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3949E+01
l.OOOOE+04
1.7187E+01
7.0109E-02
4.9262E+01
1.4718E+03
5.1357E+01
1.1132E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
8.7193E+02
l.OOOOE+04
l.OOOOE+04
7.1070E+00
2.4999E+03
1.0971E+02
l.OOOOE+04
2.8337E+01
7.0112E-02
8.7089E+01
4.9135E+03
1.2527E+02
9.3097E+00
% DIFFERENCE
42108.3 %
105618.3 %
0.0 %
74.4 %
0.0 %
0.0 %
736.3 %
899.7 %
686.5 %
0.0 %
64.9 %
0.0 %
76.8 %
233.8 %
143.9 %
736.3 %
This case illustrates the effect of higher groundwater velocities
and is analogous to S15-50. See Table 110.
124
-------
Table 114.
The Effect of Reduced Groundwater Velocity
at a 150 Meter Well.
S16-150, GW VEL 10 M/Y, DIST 150 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3692E+01
9.4591E+00
l.OOOOE+04
5.0000E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3949E+01
l.OOOOE+04
1.7187E+01
7.0109E-02
4.9262E+01
1.4718E+03
5.1357E+01
1.1132E+00
2.4492E+01
9.6872E+00
l.OOOOE+04
5.9358E+02
l.OOOOE+04
l.OOOOE+04
8.5012E-01
2.4999E+02
1.3935E+01
l.OOOOE+04
8.7101E+02
7.0112E-02
l.OOOOE+04
1.4715E+03
l.OOOOE+04
1.1136E+00
% DIFFERENCE
3.4 %
2.4 %
0.0 %
18.7 %
0.0 %
0.0 %
0.0 %
0.0 %
-0.1 %
0.0 %
4967.8 %
0.0 %
20199.6 %
0.0 %
19371.5 %
0.0 %
This case is analogous to S16-50 at a slower velocity. See Table
111. The slight increase for lead reflects the difficulty in matching
sludge concentrations exactly with the back calculation method.
125
-------
Table 115.
The Effect of Minimal Groundwater Flow
at a 150 Meter Well.
S17-150, GW VEL 1 M/Y, DIST 150 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3692E+01
9.4591E+00
l.OOOOE+04
5.0000E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3949E+01
l.OOOOE+04
1.7187E+01
7.0109E-02
4.9262E+01
1.4718E+03
5.1357E+01
1.1132E+00
2.3630E+01
9.5421E+00
l.OOOOE+04
6.8834E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3945E+01
l.OOOOE+04
8.8095E+02
7.0109E-02
l.OOOOE+04
1.4711E+03
l.OOOOE+04
1.1132E+00
% DIFFERENCE
-0.3 %
0.9 %
0.0 %
37.7 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
5025.7 %
0.0 %
20199.6 %
0.0 %
19371.5 %
0.0 %
This case is the same as S17-50. See discussion on Table 111.
Note the allowable sludge levels are even higher for degradable
chemicals because of the additional travel times during which
degradation will occur. The lead values appear to be a reflection of
inaccuracies in the back calculation method. Lead is controlled by
solubility limitations in this setting.
126
-------
Table 116.
The Effect of Higher Groundwater Velocity
at a 500 Meter Well.
S15-500, 500 M BASE CASE BUT VEL 1000 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
1.0584E+02
4.6687E+01
l.OOOOE+04
2.0969E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7638E+01
l.OOOOE+04
2.3061E+02
3.9816E-01
8.7968E+02
2.1299E+03
1.3035E+03
1.5178E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
4.1026E+03
l.OOOOE+04
l.OOOOE+04
8.5012E+00
2.9879E+03
1.8773E+02
l.OOOOE+04
4.7951E+01
3.9817E-01
1.7202E+02
l.OOOOE+04
2.0672E+02
1.1109E+01
% DIFFERENCE
9348.2 %
21319.2 %
0.0 %
95.7 %
0.0 %
0.0 %
633.7 %
899.7 %
964.3 %
0.0 %
-79.2 %
0.0 %
-80.4 %
369.5 %
-84.1 %
631.9 %
This case illustrates the effect of higher velocities and is
analogous to S15-50. See Table 110. The reduced sludge concentrations
for DDT, Lindane and TCE reflect the lower amount of degradation that
will occur because of the shorter travel times.
127
-------
Table 117.
The Effect of Lower Groundwater Velocity
at a 500 Meter Well.
S16-500, 500 M BASE CASE BUT VEL = 10 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
1.0584E+02
4.6687E+01
l.OOOOE+04
2.0969E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7638E+01
l.OOOOE+04
2.3061E+02
3.9816E-01
8.7968E+02
2.1299E+03
1.3035E+03
1.5178E+00
1.0676E+02
4.7022E+01
l.OOOOE+04
1.9345E+03
l.OOOOE+04
l.OOOOE+04
1.1591E+00
2.9879E+02
1.7669E+01
l.OOOOE+04
5.0029E+03
3.9817E-01
l.OOOOE+04
2.1310E+03
l.OOOOE+04
1.5176E+00
0.9 %
0.7 %
0.0 %
-7.7 %
0.0 %
0.0 %
0.0 %
0.0 %
0.2 %
0.0 %
2069.4 %
0.0 %
1036.8 %
0.1 %
667.2 %
0.0 %
This case is similar to S16-50. See Table 111.
128
-------
Table 118.
The Effect of Minimal Groundwater Velocity
at a 500 Meter Well.
S17-500, 500 M BASE CASE BUT VEL = 1 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
1.0584E+02
4.6687E+01
l.OOOOE+04
2.0969E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7638E+01
l.OOOOE+04
2.3061E+02
3.9816E-01
8.7968E+02
2.1299E+03
1.3035E+03
1.5178E+00
1.0676E+02
4.7022E+01
l.OOOOE+04
1.9332E+03
l.OOOOE+04
l.OOOOE+04
1.1591E+00
2.9879E+02
1.7669E+01
l.OOOOE+04
5.0029E+03
3.9817E-01
l.OOOOE+04
2.1310E+03
l.OOOOE+04
1.5176E+00
0.9 %
0.7 %
0.0 %
-7.8 %
0.0 %
0.0 %
0.0 %
0.0 %
0.2 %
0.0 %
2069.4 %
0.0 %
1036.8 %
0.1 %
667.2 %
0.0 %
This case is similar to S16-50. See Table 111.
129
-------
Table 119.
The Effect of Higher Groundwater Velocity
at a 1000 Meter Well.
S15-1000, 1000 M BASE CASE BUT VEL 1000 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3709E+02
1.0423E+02
l.OOOOE+04
6.3796E+03
l.OOOOE+04
l.OOOOE+04
1.7503E+00
4.5136E+02
2.7927E+01
l.OOOOE+04
3.1791E+03
1.1857E+00
l.OOOOE+04
3.3130E+03
l.OOOOE+04
2.2927E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
8.8982E+03
l.OOOOE+04
l.OOOOE+04
1.7492E+01
4.5121E+03
2.8727E+02
l.OOOOE+04
1.1528E+02
1.1857E+00
4.1598E+02
l.OOOOE+04
4.9692E+02
2.2952E+01
% DIFFERENCE
4117.8 %
9494.2 %
0.0 %
39.5 %
0.0 %
0.0 %
899.4 %
899.7 %
928.6 %
0.0 %
-96.4 %
0.0 %
-95.8 %
201.8 %
-95.0 %
901.1 %
This case is similar to S15-50. See Table 110 and Table 116
130
-------
Table 120.
The Effect of Lower Groundwater Velocity
at a 1000 Meter Well.
S16-1000, 1000 M BASE CASE BUT VEL = 10 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
2.3709E+02
1.0423E+02
l.OOOOE+04
6.3796E+03
l.OOOOE+04
l.OOOOE+04
1.7503E+00
4.5136E+02
2.7927E+01
l.OOOOE+04
3.1791E+03
1.1857E+00
l.OOOOE+04
3.3130E+03
l.OOOOE+04
2.2927E+00
2.3722E+02
1.0428E+02
l.OOOOE+04
6.3796E+03
l.OOOOE+04
l.OOOOE+04
1.7509E+00
4.5121E+02
2.7882E+01
l.OOOOE+04
l.OOOOE+04
1.1857E+00
l.OOOOE+04
3.3117E+03
l.OOOOE+04
2.2924E+00
0.1 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
-0.2 %
0.0 %
214.6 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
This case is similar to S16-50. See Table 111. It should be
noted, however, that the travel distance is so large that the extra
travel time for degradables has become insignificant because the sludge
concentrations for Lindane and TCE have reached the maximum level.
131
-------
Table 121.
The Effect of Minimal Groundwater Velocity
at a 1000 Meter Well.
S17-1000, 1000 M BASE CASE BUT VEL = 1 M/Y
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
2.3709E+02
1.0423E+02
l.OOOOE+04
6.3796E+03
l.OOOOE+04
l.OOOOE+04
1.7503E+00
4.5136E+02
2.7927E+01
l.OOOOE+04
3.1791E+03
1J857E+00
l.OOOOE+04
3.3130E+03
l.OOOOE+04
2.2927E+00
2.3722E+02
1.0428E+02
l.OOOOE+04
6.3796E+03
l.OOOOE+04
l.OOOOE+04
1.7509E+00
4.5121E+02
2.7882E+01
l.OOOOE+04
l.OOOOE+04
1.1857E+00
l.OOOOE+04
3.3146E+03
l.OOOOE+04
2.2924E+00
0.1 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
-0.2 %
0.0 %
214.6 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
This case is similar to S16-1000. See Table 120.
132
-------
Table 122.
The Effect of a Very Thick Aquifer
at a 50 Meter Well.
S18-50, AQUIFER THICKNESS = 560M, DIST = 50 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY %
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
5.8201E+00
2.6302E+00
l.OOOOE+04
2.3343E+02
l.OOOOE+04
l.OOOOE+04
6.7523E-01
2.3757E+02
1.1471E+01
l.OOOOE+04
5.0370E+00
2.1961E-02
1.4748E+01
9.6306E+02
2.1855E+01
8.8296E-01
DIFFERENCE
-5.2 %
-4.3 %
0.0 %
-2.5 %
0.0 %
0.0 %
4.9 %
5.2 %
5.1 %
0.0 %
3.0 %
0.0 %
3.2 %
2.6 %
3.3 %
4.9 %
This case illustrates the effect of a thicker aquifer on allowable
concentrations. THere are no effects on chemicals controlled by vapor
considerations or those that are already at the maximum allowable
sludge concentrations. For all others, the effects are small,
indicating that vertical dispersion is not a real limitation for the
base case. The negative values for metals are indicative of
inaccuracies in the back calculation method for setting allowable
sludge levels.
133
-------
Table 123.
The Effect of a Thick Aquifer
at a 50 Meter Well.
S19-50, AQUIFER THICKNESS = 78.6M, DIST = 50 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY %
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
6.1382E+00
2.7461E+00
l.OOOOE+04
2.3929E+02
l.OOOOE+04
l.OOOOE+04
6.7523E-01
2.3757E+02
1.1471E+01
l.OOOOE+04
4.9948E+00
2.1961E-02
1.4748E+01
9.6255E+02
2.1855E+01
8.8296E-01
DIFFERENCE
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
4.9 %
5.2 %
5.1 %
0.0 %
2.1 %
0.0 %
3.2 %
2.5 %
3.3 %
4.9 %
This case is the same as S18-50 with the thinner aquifer but still
thicker than the base case. The results are virtually identical to
S18-50. See Table 122.
134
-------
Table 124.
The Effect of a Thin Aquifer
at a 50 Meter Well.
S20-50, AQUIFER THICKNESS = 5M, DIST = 50 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
6.0825E+00
2.7370E+00
1.4983E+03
2.3912E+02
l.OOOOE+04
6.0132E+02
2.6957E-01
9.4915E+01
4.5045E+00
l.OOOOE+04
2.2131E+00
2.1961E-02
6.1771E+00
5.3348E+02
9.5351E+00
3.5321E-01
-0.9 %
-0.4 %
-85.0 %
-0.1 %
0.0 %
-94.0 %
-58.1 %
-58.0 %
-58.7 %
0.0 %
-54.8 %
0.0 %
-56.8 %
-43.2 %
-54.9 %
-58.0 %
This case illustrates the effect of reducing aquifer thickness.
Aside from chemicals already at maximum allowable sludge levels
(Mercury and Chlordane) and DMN which is controlled by vapor
considerations, the chemicals respond with a reduced allowable sludge
concentration because of the restriction on vertical dispersion caused
by thinning the aquifer.
135
-------
Table 125.
The Effect of a Very Thick Aquifer
at a 150 Meter Well.
S18-150, AQUIFER THICKNESS = 560M, DIST = 150 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.O.OOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
2.3692E+01
9.4591E+00
l.OOOOE+04
5.0000E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3949E+01
l.OOOOE+04
1.7187E+01
7.0109E-02
4.9262E+01
1.4718E+03
5.1357E+01
1.1132E+00
2.4177E+01
9.5853E+00
l.OOOOE+04
4.7115E+02
l.OOOOE+04
l.OOOOE+04
1.7591E+00
4.8860E+02
2.8669E+01
l.OOOOE+04
3.1010E+01
7.0112E-02
8.9228E+01
2.3724E+03
9.3540E+01
2.3049E+00
2.0 %
1.3 %
0.0 %
-5.8 %
0.0 %
0.0 %
107.0 %
95.4 %
105.5 %
0.0 %
80.4 %
0.0 %
81.1 %
61.2 %
82.1 %
107.1 %
This case is similar to S18-50 but for a greater saturated zone
travel distance. The impacts are much greater in this case because at
the longer distances, the vertical dispersion goes to much greater
depths. Hence, species not controlled by vapor considerations or
geochemistry, or those for which sludge concentrations are already
maximized, benefit from the greater volume of groundwater for dilution.
136
-------
Table 126.
The Effect of a Thick Aquifer
at a 150 Meter Well.
S19-150, AQUIFER THICKNESS = 78.6M, DIST = 150 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
2.3692E+01
9.4591E+00
l.OOOOE+04
5.0000E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3949E+01
l.OOOOE+04
1.7187E+01
7.0109E-02
4.9262E+01
1.4718E+03
5.1357E+01
1.1132E+00
2.4214E+01
9.6016E+00
l.OOOOE+04
5.6360E+02
l.OOOOE+04
l.OOOOE+04
1.7641E+00
4.8816E+02
2.8637E+01
l.OOOOE+04
3.1007E+01
7.0115E-02
8.9247E+01
2.3725E+03
9.3397E+01
2.3114E+00
2.2 %
1.5 %
0.0 %
12.7 %
0.0 %
0.0 %
107.6 %
95.2 %
105.3 %
0.0 %
80.4 %
0.0 %
81.2 %
61.2 %
81.9 %
107.6 %
This case is analogous to S18-50 with a thinner aquifer. The
impacts are nearly identical since 78.6 meters of thickness is enough
to allow the extra vertical dispersion. See Table 125.
137
-------
Table 127.
The Effect of a Thin Aquifer
at a 150 Meter Well.
S20-150, AQUIFER THICKNESS = 5M, DIST = 150 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
2.3692E+01
9.4591E+00
l.OOOOE+04
5.0000E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3949E+01
l.OOOOE+04
1.7187E+01
7.0109E-02
4.9262E+01
1.4718E+03
5.1357E+01
1.1132E+00
1.4599E+01
6.5689E+00
2.8392E+03
5.2106E+02
l.OOOOE+04
1.0406E+03
2.8362E-01
8.3209E+01
4.6764E+00
l.OOOOE+04
5.8182E+00
7.0115E-02
1.6410E+01
5.7531E+02
1.7106E+01
3.7087E-01
-38.4 %
-30.6 %
-71.6 %
4.2 %
0.0 %
-89.6 %
-66.6 %
-66.7 %
-66.5 %
0.0 %
-66.1 %
0.0 %
-66.7 %
-60.9 %
-66.7 %
-66.7 %
This case is similar to S20-50. The longer distance provides more
longitudinal dispersion but makes the thin aquifer more restrictive
with respect to vertical dispersion. See Table 124.
138
-------
Table 128.
The Effect of a Very Thick Aquifer
At a 500 Meter Well.
S18-500, 500 M BASE CASE BUT WITH AQUIFER THICKNESS = 560 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
1.0584E+02
4.6687E+01
l.OOOOE+04
2.0969E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7638E+01
l.OOOOE+04
2.3061E+02
3.9816E-01
8.7968E+02
2.1299E+03
1.3035E+03
1.5178E+00
6.4628E+02
2.2284E+02
l.OOOOE+04
2.1034E+03
l.OOOOE+04
l.OOOOE+04
7.1950E+00
1.8368E+03
7.5537E+01
l.OOOOE+04
1.0726E+03
1.1857E+00
4.0420E+03
l.OOOOE+04
7.7178E+03
9.4274E+00
510.6 %
377.3 %
0.0 %
0.3 %
0.0 %
0.0 %
521.0 %
514.5 %
328.3 %
0.0 %
365.1 %
197.8 %
359.5 %
369.5 %
492.1 %
521.1 %
This case is the same as S18-50 but with a much longer travel
distance. As a consequence, the vertical dispersion potential is
greater and a thin aquifer has a greater confining influence. Hence,
the allowable sludge concentrations are much higher here.
139
-------
Table 129.
The Effect of a Thick Aquifer
at a 500 Meter Well.
S19-500, 500 M BASE CASE BUT WITH AQUIFER THICKNESS = 78.6 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
1.0584E+02
4.6687E+01
l.OOOOE+04
2.0969E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7638E+01
l.OOOOE+04
2.3061E+02
3.9816E-01
8.7968E+02
2.1299E+03
1.3035E+03
1.5178E+00
5.9758E+02
2.5547E+02
l.OOOOE+04
2.2659E+03
l.OOOOE+04
l.OOOOE+04
5.8030E+00
1.5176E+03
6.9544E+01
l.OOOOE+04
8.9198E+02
3.9819E-01
3.8635E+03
8.7953E+03
6.5958E+03
7.5881E+00
464.6 %
447.2 %
0.0 %
8.1 %
0.0 %
0.0 %
400.8 %
407.7 %
294.3 %
0.0 %
286.8 %
0.0 %
339.2 %
312.9 %
406.0 %
399.9 %
This case is the same as S19-50 at a longer travel distance.
Therefore, the benefits are similar but larger in magnitude since a
thin aquifer is more confining at greater distances. See Table 123.
140
-------
Table 130.
The Effect of a Thin Aquifer
at a 500 Meter Well.
S20-500, 500 M BASE CASE BUT WITH AQUIFER THICKNESS = 5 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
1.0584E+02
4.6687E+01
l.OOOOE+04
2.0969E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7638E+01
l.OOOOE+04
2.3061E+02
3.9816E-01
8.7968E+02
2.1299E+03
1.3035E+03
1.5178E+00
3.4302E+01
1.5721E+01
l.OOOOE+04
1.7366E+03
l.OOOOE+04
4.3817E+03
3.8687E-01
9.9624E+01
5.8877E+00
l.OOOOE+04
7.9240E+01
3.9819E-01
2.9324E+02
7.3865E+02
4.3508E+02
5.0655E-01
-67.6 %
-66.3 %
0.0 %
-17.2 %
0.0 %
-56.2 %
-66.6 %
-66.7 %
-66.6 %
0.0 %
-65.6 %
0.0 %
-66.7 %
-65.3 %
-66.6 %
-66.6 %
This case is the same as S20-150 but the travel distances are
greater. While a thin aquifer is more confining at greater distances,
the relative effects are quite similar between the two cases because
horizontal and longitudinal dispersion are playing a larger role at the
greater distance. See Table 124.
141
-------
Table 131.
The Effect of a Very Thick Aquifer
at a 1000 Meter Well.
S18-1000, 1000 M BASE CASE BUT WITH AQUIFER THICKNESS = 560 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3709E+02
1.0423E+02
l.OOOOE+04
6.3796E+03
l.OOOOE+04
l.OOOOE+04
1.7503E+00
4.5136E+02
2.7927E+01
l.OOOOE+04
3.1791E+03
1.1857E+00
l.OOOOE+04
3.3130E+03
l.OOOOE+04
2.2927E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
7.6686E+03
l.OOOOE+04
l.OOOOE+04
2.0954E+01
5.4921E+03
1.8069E+02
l.OOOOE+04
l.OOOOE+04
1.1857E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
2.7405E+01
% DIFFERENCE
4117.8 %
9494.2 %
0.0 %
20.2 %
0.0 %
0.0 %
1097.2 %
1116.8 %
547.0 %
0.0 %
214.6 %
0.0 %
0.0 %
201.8 %
0.0 %
1095.3 %
This case is similar to S18-500 but at a greater travel distance.
Therefore, the effects are the same but more pronounced since there is
greater distance over which vertical dispersion can dilute the plume.
See Table 122.
142
-------
Table 132.
The Effect of a Thick Aquifer
at a 1000 Meter Well.
S19-1000, AQUIFER THICKNESS 78.6 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
4.94E-02
l.OOE-02
2.40E-01
4.90E-02
2.29E-04
5.13E-01
4.99E-03
3.01E-04
2.48E-01
O.OOE+00
8.02E-03
O.OOE+00
2.56E-03
4.41E-04
2.89E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.37E+02
1.04E+02
l.OOE+04
6.35E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
2.80E+01
l.OOE+04
3.18E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
l.OOE+04
l.OOE+04
l.OOE+04
7.64E+03
l.OOE+04
l.OOE+04
9.18E+00
2.36E+03
1.33E+02
l.OOE+04
8.73E+03
1.19E+00
l.OOE+04
l.OOE+04
l.OOE+04
1.20E+01
% DIFFERENCE
4115.9 %
9496.9 %
0.0 %
20.2 %
0.0 %
0.0 %
424.7 %
423.5 %
375.7 %
0.0 %
174.7 %
0.0 %
0.0 %
201.8 %
0.0 %
423.8 %
This case is similar to S19-500 but at a longer travel distance.
The effects are the same but of greater magnitude since aquifer
thickness is more confining at greater flow distances. See Table 122.
143
-------
Table 133.
The Effect of a Thin Aquifer
at a 1000 Meter Well.
S20-1000, AQUIFER THICKNESS 5 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
4.94E-02
l.OOE-02
2.40E-01
4.90E-02
2.29E-04
5.13E-01
4.99E-03
3.01E-04
2.48E-01
O.OOE+00
8.02E-03
O.OOE+00
2.56E-03
4.41E-04
2.89E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
2.37E+02
1.04E+02
l.OOE+04
6.35E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
2.80E+01
l.OOE+04
3.18E+03
4.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
6.83E+01
3.11E+01
l.OOE+04
2.60E+03
l.OOE+04
l.OOE+04
5.84E-01
1.51E+02
9.30E+00
l.OOE+04
1.24E+03
1.19E+00
5.21E+03
1.13E+03
5.77E+03
7.65E-01
-71.2 %
-70.2 %
0.0 %
-59.0 %
0.0 %
0.0 %
-66.6 %
-66.6 %
-66.8 %
0.0 %
-61.1 %
0.0 %
-47.9 %
-66.0 %
-42.3 %
-66.6 %
This case is similar to S20-500 with a longer travel distance.
Since longer travel distances would normally lead to vertical
dispersion to greater depths, the thin aquifer dimensions are more
confining for this case. THerefore, the impact of the thinner aquifer
is more pronounced. See Table 124.
144
-------
Table 134.
The Effect of a Lower Oxidation State
at a 50 Meter Well.
S21-50, EH 150 MV, PH 6.0, DIST = 50 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY %
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
6.1599E+00
2.7423E+00
l.OOOOE+04
2.3936E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8846E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1277E+01
8.4160E-01
DIFFERENCE
0.3 %
-0.2 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
-0.2 %
0.0 %
0.0 %
0.0 %
0.6 %
0.0 %
This case illustrates the effect of a lower state of oxidation in
the groundwater. It would be expected to change results for metals
affected by groundwater geochemistry. In this case, the change had no
significant impact on solubility levels and so would not change
allowable sludge levels.
145
-------
Table 135.
The Effect of Reducing Conditions and
Elevated pH at a 50 Meter Well.
S22-50, EH -200 MV, PH 7.0, DIST = 50 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
5.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
l.OOOOE+04
2.7423E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8846E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1277E+01
8.4160E-01
% DIFFERENCE
162777.1 %
-0.2 %
0.0 %
4077.1 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
-0.2 %
0.0 %
0.0 %
0.0 %
0.6 %
0.0 %
This case illustrates the effect of encountering reducing
conditions and a higher pH in the groundwater. The solubility of two
chemicals was greatly effected. Both Arsenic and Lead be' .me
sufficiently insoluble to control concentrations below risk levels and
allow sludge limits to go to the maximum level of 10,000 mg/kg.
146
-------
Table 136.
The Effect of a Lower Oxidation State
at a 150 Meter Well.
S21 150, EH 150 MV, PH 6.0, DIST 150 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY %
2.3692E+01
9.4591E+00
l.OOOOE+04
5.0000E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3949E+01
l.OOOOE+04
1.7187E+01
7.0109E-02
4.9262E+01
1.4718E+03
5.1357E+01
1.1132E+00
2.8004E+01
9.7000E+00
l.OOOOE+04
5.1058E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3938E+01
l.OOOOE+04
1.7201E+01
7.0109E-02
4.9262E+01
1.4711E+03
5.1291E+01
1.1132E+00
DIFFERENCE
18.2 %
2.5 %
0.0 %
2.1 %
0.0 %
0.0 %
0.0 %
0.0 %
-0.1 %
0.0 %
0.1 %
0.0 %
0.0 %
0.0 %
-0.1 %
0.0 %
This case is similar to S21-50 at a greater travel distance. The
apparent effect on Arsenic is likely to be a result of the back
calculations rather than an impact since Arsenic solubility is not
effected in this Eh range. See Table 134.
147
-------
Table 137.
The Effect of Reducing Conditions and
Elevated pH at a 150 Meter Well.
S22-150, EH -200 MV, PH 7.0, DIST = 150 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.020.0E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY
2.3692E+01
9.4591E+00
l.OOOOE+04
5.0000E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3949E+01
l.OOOOE+04
1.7187E+01
7.0109E-02
4.9262E+01
1.4718E+03
5.1357E+01
1.1132E+00
l.OOOOE+04
9.6358E+00
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3945E+01
l.OOOOE+04
1.7201E+01
7.0109E-02
4.9262E+01
1.4711E+03
5.1291E+01
1.1132E+00
% DIFFERENCE
42108.3 %
1.9 %
0.0 %
1900.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.1 %
0.0 %
0.0 %
0.0 %
-0.1 %
0.0 %
This case is the same as S22-50 at a longer travel distance.
results are the same as well. See Table 135.
The
148
-------
Table 138.
The Effect of a Lower Oxidation State
at a 500 Meter Well.
S21-500, 500 M BASE CASE BUT EH = 150 MV, PH = 6.0
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY %
1.0584E+02
4.6687E+01
l.OOOOE+04
2.0969E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7638E+01
l.OOOOE+04
2.3061E+02
3.9816E-01
8.7968E+02
2.1299E+03
1.3035E+03
1.5178E+00
1.1048E+02
4.6636E+01
l.OOOOE+04
2.4780E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7658E+01
l.OOOOE+04
2.3053E+02
3.9816E-01
8.7968E+02
2.1289E+03
1.3018E+03
1.5178E+00
DIFFERENCE
4.4 %
-0.1 %
0.0 %
18.2 %
0.0 %
0.0 %
0.0 %
0.0 %
0.1 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
-0.1 %
0.0 %
This case is analogous to S21-500 at a longer travel distance.
The apparent effect on Lead is a result of poor resolution in the back
calculation to allowable sludge levels. See Table 134.
149
-------
Table 139.
The Effect of Reducing Conditions and
Elevated pH at a 500 Meter Well.
S22-500, 500 M BASE CASE BUT EH = -200 MV, PH = 7.0
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
1.0584E+02
4.6687E+01
l.OOOOE+04
2.0969E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7638E+01
l.OOOOE+04
2.3.061E+02
3.9816E-01
8.7968E+02
2.1299E+03
1.3035E+03
1.5178E+00
l.OOOOE+04
4.6952E+01
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7658E+01
l.OOOOE+04
2.3053E+02
3.9816E-01
8.7968E+02
2.1289E+03
1.3018E+03
1.5178E+00
9348.2 %
0.6 %
0.0 %
376.9 %
0.0 %
0.0 %
0.0 %
0.0 %
0.1 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
-0.1 %
0.0 %
This case is the same as S22-50 at a longer travel distance,
Table 135.
See
150
-------
Table 140.
The Effect of a Lower Oxidation State
at a 1000 Meter Well.
S21 1000, EH 150 MV, PH 6.0
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
4.94E-02
l.OOE-02
2.40E-01
4.90E-02
2.29E-04
5.13E-01
4.99E-03
3.01E-04
2.48E-01
O.OOE+00
8.02E-03
O.OOE+00
2.56E-03
4.41E-04
2.89E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY %
2.37E+02
1.04E+02
l.OOE+04
6.35E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
2.80E+01
l.OOE+04
3.18E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
2.46E+02
1.04E+02
l.OOE+04
6.35E+03
l.OOE+04
l.OOE+04
1.75E+00
4.53E+02
2.80E+01
l.OOE+04
3.18E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
DIFFERENCE
3.8 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.3 %
0.2 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
This case is the same as S21-50 at a longer travel distance.
Table 134.
See
151
-------
Table 141.
The Effect of Reducing Conditions and
Elevated pH at a 1000 Meter Well.
S22-1000, EH -200 MV, PH 7.0
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
4.94E-02
l.OOE-02
2.40E-01
4.90E-02
2.29E-04
5.13E-01
4.99E-03
3.01E-04
2.48E-01
O.OOE+00
8.02E-03
O.OOE+00
2.56E-03
4.41E-04
2.89E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
2.37E+02
1.04E+02
l.OOE+04
6.35E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
2.80E+01
l.OOE+04
3.18E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
l.OOE+04
1.04E+02
l.OOE+04
l.OOE+04
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
2.79E+01
l.OOE+04
3.18E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
4115.9 %
0.2 %
0.0 %
57.4 %
0.0 %
0.0 %
0.0 %
0.0 %
-0.3 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
0.0 %
This case is the same as S22-50 at longer travel distances. See
Table 135. The effects on Lead are reduced because the maximum
allowable sludge level reached the arbitrary cutoff of 10,000 mg/kg.
152
-------
Table 142.
The Effect of Increased Sludge Moisture
Content at a 50 Meter Well.
S23-50, SLUDGE MOISTURE CONTENT 0.95, DIST = 50 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E-I-02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
3.4420E+01
1.2971E+01
l.OOOOE+04
9.7563E+02
l.OOOOE+04
l.OOOOE+04
6.7480E-01
2.2590E+02
9.1168E+00
l.OOOOE+04
5.4152E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1277E+01
8.8218E-01
460.6 %
372.2 %
0.0 %
307.5 %
0.0 %
0.0 %
4.8 %
0.0 %
16.4 %
0.0 %
10.7 %
0.0 %
0.0 %
0.0 %
0.6 %
4.8 %
This case illustrates the effect of a higher initial moisture
content in the sludge. The greater moisture level means there are
correspondingly fewer solids in a given volume of sludge (e.g. the
landfill) and, therefore, a smaller total inventory of contaminant. As
a consequence, the pulse width (release time) is reduced relative to
the travel time, this allows for greater effects from dispersion in
chemicals where the release time is small compared to the travel time.
The effects are noted on four contaminants: Arsenic, Cadmium, Lead and
BEHP. The effects on BEHP are negative because the reduced sludge
concentrations reduces the vapor release rate and BEHP risk is vapor
controlled.
153
-------
Table 143.
The Effect of Decreased Moisture
Content at a 50 Meter Well.
S24-50, SLUDGE MOISTURE CONTENT 0.60, HEL = l.OE-04, DIST = 50 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3'OOOE+OO
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
6.1396E+00
2.7471E+00
l.OOOOE+04
2.3940E+02
l.OOOOE+04
l.OOOOE+04
6.4376E-01
2.2590E+02
1.0911E+01
l.OOOOE+04
4.8922E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1159E+01
8.4160E-01
3.0689E+00
1.3720E+00
l.OOOOE+04
1.1961E+02
l.OOOOE+04
l.OOOOE+04
6.4267E-01
2.2590E+02
1.0913E+01
l.OOOOE+04
4.8880E+00
2.1959E-02
1.4286E+01
9.3867E+02
2.1277E+01
8.4177E-01
-50.0 %
-50.1 %
0.0 %
-50.0 %
0.0 %
0.0 %
-0.2 %
0.0 %
0.0 %
0.0 %
-0.1 %
0.0 %
0.0 %
0.0 %
0.6 %
0.0 %
This case is the opposite of S23-50. The pulse widths (release
times) are increased in this case and, therefore, allowable sludge
levels are reduced for Arsenic, Cadmium, and Lead. See Table 142. The
effects on BEHP are negligible because the allowable levels are driven
by vapors and the controlling concentration was reached near the base
case moisture content.
154
-------
Table 144.
The Effect of Increased Sludge Moisture Content
at a 150 Meter Well.
S23-150, SLUDGE MOISTURE CONTENT 0.95, DIST 150 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
2.3692E+01
9.4591E+00
l.OOOOE+04
5.0000E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3949E+01
l.OOOOE+04
1.7187E+01
7.0109E-02
4.9262E+01
1.4718E+03
5.1357E+01
1.1132E+00
1.0673E+02
4.0770E+01
l.OOOOE+04
2.0758E+03
l.OOOOE+04
l.OOOOE+04
8.4987E-01
2.5007E+02
1.6912E+01
l.OOOOE+04
1.7193E+01
7.0109E-02
4.8020E+01
1.4711E+03
5.1291E+01
1.1139E+00
350.5 %
331.0 %
0.0 %
315.2 %
0.0 %
0.0 %
0.0 %
0.0 %
21.2 %
0.0 %
0.0 %
0.0 %
-2.5 %
0.0 %
-0.1 %
0.1 %
This case is the same as S23-50 at a greater travel distance. See
Table 142. The increase in BEHP allowable levels reflects a change
over from vapor driven to groundwater transport driven mechanisms.
155
-------
Table 145.
The Effect of Decreased Sludge Moisture
Content at a 150 Meter Well.
S24-150, SLUDGE MOISTURE CONTENT 0.60, DIST 150 M
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
2.3692E+01
9.4591E+00
l.OOOOE+04
5.0000E+02
l.OOOOE+04
l.OOOOE+04
8.4983E-01
2.5007E+02
1.3949E+01
l.OOOOE+04
1.7187E+01
7.0109E-02
4.9262E+01
1.4718E+03
5.1357E+01
1.1132E+00
1.2000E+01
4.8447E+00
l.OOOOE+04
2.5378E+02
l.OOOOE+04
l.OOOOE+04
8.5009E-01
2.5007E+02
1.3940E+01
l.OOOOE+04
1.1809E+01
7.0109E-02
4.8427E+01
1.4711E+03
5.1291E+01
9.3116E-01
-49.3 %
-48.8 %
0.0 %
-49.2 %
0.0 %
0.0 %
0.0 %
0.0 %
-0.1 %
0.0 %
-31.3 %
0.0 %
-1.7 %
0.0 %
-0.1 %
-16.4 %
This case is the same as S24-50 at a longer travel distance. See
Table 143. Note that at 150 meters, the travel time is long enough for
reduced pulse width to effect allowable DDT sludge concentrations.
156
-------
Table 146.
The Effect of Increased Sludge Moisture
Content at a 500 Meter Well.
S23-500, 500 M BASE CASE BUT WITH SLUDGE MOISTURE CONTENT = 0.95
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
1.0584E+02
4.6687E+01
l.OOOOE+04
2.0969E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7638E+01
l.OOOOE+04
2.3061E+02
3.9816E-01
8.7968E+02
2.1299E+03
1.3035E+03
1.5178E+00
4.3573E+02
1.9038E+02
l.OOOOE+04
7.8150E+03
l.OOOOE+04
l.OOOOE+04
1.0952E+00
2.9889E+02
5.0188E+01
l.OOOOE+04
2.3043E+02
3.9816E-01
8.8110E+02
2.1289E+03
1.0341E+03
1.4551E+00
311.7 %
307.8 %
0.0 %
272.7 %
0.0 %
0.0 %
-5.5 %
0.0 %
184.5 %
0.0 %
-0.1 %
0.0 %
0.2 %
0.0 %
-20.7 %
-4.1 %
This case is the same as S23-50 at a longer travel distance.
Table 142.
See
157
-------
Table 147.
The Effect of Decreased Sludge Moisture
Content at a 500 Meter Well.
S24-500, 500 M BASE CASE BUT WITH SLUDGE MOISTURE CONTENT = 0.60
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
5.0000E-02
l.OOOOE-02
1.3000E+00
5.0000E-02
2.0000E-03
1.7500E+00
5.0000E-03
3.0000E-04
2.4800E-01
2.1000E-03
1.0200E-02
l.OOOOE-04
4.0000E-03
4.5400E-04
5.0000E-03
5.0000E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
1.0584E+02
4.6687E+01
l.OOOOE+04
2.0969E+03
l.OOOOE+04
l.OOOOE+04
1.1587E+00
2.9889E+02
1.7638E+01
l.OOOOE+04
2.3061E+02
3.9816E-01
8.7968E+02
2.1299E+03
1.3035E+03
1.5178E+00
5.2839E+01
2.3320E+01
l.OOOOE+04
1.2394E+03
l.OOOOE+04
l.OOOOE+04
1.1590E+00
2.9889E+02
1.9167E+01
l.OOOOE+04
2.3028E+02
3.9816E-01
8.8049E+02
2.1289E+03
1.3018E+03
1.5185E+00
-50.1 %
-50.1 %
0.0 %
-40.9 %
0.0 %
0.0 %
0.0 %
0.0 %
8.7 %
0.0 %
-0.1 %
0.0 %
0.1 %
0.0 %
-0.1 %
0.0 %
This case is the same as S24-50 at a longer travel distance.
Table 143.
See
158
-------
Table 148.
The Effect of Increased Sludge Moisture
Content at a 1000 Meter Well.
S23-1000, SLUDGE MOISTURE CONTENT 0.95
CHEMICAL
ARSENIC
CADMIUM
COPPER
LEAD
MERCURY
NICKEL
BENZENE
B(A)P
BEHP
CHLORDANE
DDT
DMN
LINDANE
PCB
TCE
TOXAPHENE
HEALTH
STANDARD
(MG/L)
4.94E-02
l.OOE-02
2.40E-01
4.90E-02
2.29E-04
5.13E-01
4.99E-03
3.01E-04
2.48E-01
O.OOE+00
8.02E-03
O.OOE+00
2.56E-03
4.41E-04
2.89E-03
5.00E-03
ALLOWABLE SLUDGE
CONCENTRATION (MG/KG)
BASELINE SENSITIVITY % DIFFERENCE
2.37E+02
1.04E+02
l.OOE+04
6.35E+03
l.OOE+04
l.OOE+04
1.75E+00
4.51E+02
2.80E+01
l.OOE+04
3.18E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.29E+00
9.57E+02
4.15E+02
l.OOE+04
l.OOE+04
l.OOE+04
l.OOE+04
1.71E+00
4.53E+02
7.71E+01
l.OOE+04
3.18E+03
1.19E+00
l.OOE+04
3.31E+03
l.OOE+04
2.36E+00
303.2 %
298.5 %
0.0 %
57.4 %
0.0 %
0.0 %
-2.2 %
0.3 %
175.5 %
0.0 %
0.1 %
0.0 %
0.0 %
0.0 %
0.0 %
3.0 %
This case is the same as S23-50 at a longer travel distance.
Tables 142 and 144.
See
159
-------
APPENDIX C
Approved Methods for Site-Specific Parameters
-------
APPROVED METHODS FOR
SITE-SPECIFIC PARAMETERS
Site-specific determinations of the maximum allowable
pollutant concentrations in the sludge may be made under certain
conditions (See Chapter 5.) Before a site-specific determination
can be made, however, the basic information for each parameter
must be obtained. Where standard methods exist, they"must be
used in order to validate the site-specific inputs to the
SLUDGEMAN computer model. This appendix catalogs the acceptable
standard methods or other sources for these parameters.
EH
The pH of^the groundwater may be measured by using Standard
Method D 1293-78, Standard Test Methods for pH of Water. [ASTM,
1982] Either Method A or Method B is acceptable for this
regulation since the input will be expressed to the nearest pH
unit (6 or 7) .
Eh
Standard Method D 1498-76, Standard Practice for oxidation-
reduction potential of water is the acceptable method for Eh.
The value measured is then compared to the allowable inputs and
the closest value (-200 mv, +150 mv, or +500 mv) is chosen as the
input. [ASTM, 1982]
Soil Type
The soil type parameter is more properly defined as the soil
texture as classified by the Soil Conservation Service. The soil
texture may be determined by the Particle Fractionization and
Particle-size Analysis in Methods of Soil Analysis. [Black, 1982]
From this analysis the percent clay, sand, and silt may be
determined. This information is used to determine the soil
texture by locating the intersection of the percentages on the
Soil Conservation Service soil textural classification chart.
[SCS, 1951]
Depth to Groundwater
The depth to groundwater may be measured in any
representative well. Measurements may need to be taken monthly
for areas with greatly varying water tables. In this case, the
smallest depth to groundwater (the highest water table) is the
value which is input into the computer model.
C-l
-------
Net Recharge is a parameter not easily measured in the
field. For the purposes of this regulation, an estimate can be
made from precipatat ion (either from area records or
estrapolation) and evapotranspirat ion values. Evapotranspiration
balues may be estimated from measurements of pan evaporation.
The evapotranspirat ion value is subtracted from the precipatat ion
value to arrive at the estimated recharge value. If the rainfall
is seasonal, then monthly measurements should be made and
averaged over the year.
The Kd value for metals may be estimated using the method of
Gerritse et al. [1982]. Gerritse made estimates of Kds in sand
and sandy loam soils. The same methodology may be used for other
soil textures.
For organics the Kd may be estimated from the Koc . The Koc
is estimated using the method in Lymari et . al. [1982] The
fraction of organic carbon ( f oc ) is measured using the Walkley-
Black method. [Black, 1982] The Kd is then estimated from the
equation:
Kd " Koc x f
oc
C-2
-------
REFERENCES
ASTM (American Society tor Testing and Materials. 1982. Annual
Book of ASTM Standards. Part 31 - Water. Easton, FID.
Black, C.A., 1982. Methods of Soil Analysis. Am. Soc. of
Agronomy Monograph #9.
Gerritse, R.G., R. Vriesema, J.W. Dalenberg, and H.P. DeRoos.
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Lyman, W.J. 1982. Adsorption Coefficients for Soils and
Sediments. Chapter 4. In: Handbook of Chemical Property
Estimation Methods. McGraw-Hill Book Co., New York, NY.
Soil Conservation Service, 1951. Soil survey manual; USDA.
C-3
-------
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