United States Office of Research and Office of Solid Waste and EPA/542/R-99/011A
Environmental Protection Development Emergency Response December 1999
Agency Washington, DC 20460 Washington, DC 20460
vvEPA Hydraulic Optimization
Demonstration for
Groundwater Pump-
and-Treat Systems
Volume I: Pre-Optimization
Screening (Method and
Demonstration)
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FINAL REPORT
HYDRAULIC OPTIMIZATION DEMONSTRATION FOR
GROUNDWATER PUMP-AND-TREAT SYSTEMS
VOLUME 1:
PRE-OPTIMIZATION SCREENING (METHOD AND DEMONSTRATION)
Prepared by:
Rob Greenwald
HSI GeoTrans
2 Paragon Way
Freehold, New Jersey 07728
Prepared For:
Mr. Ron Drake
Dynamac Corporation
3601 OakridgeRoad
Ada, Oklahoma 74820
On Behalf Of:
Mr. Dave Burden
U.S. Environmental Protection Agency
Subsurface Protection and Remediation Division
P.O.Box 1198
Ada, Oklahoma 74820
HSI GEOTRANS PROJECT HO 12-002 JUNE30,1999
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PREFACE
This work was performed for the U.S. Environmental Protection Agency (U.S. EPA) under Dynamac Contract No.
68-C4-0031. The technical work was performed by HSI GeoTrans under Subcontract No. S-OKOO-001. The final
report is presented in two volumes:
Volume 1: Pre-Optimization Screening (Method and Demonstration)
Volume 2: Application of Hydraulic Optimization
Volume 1 provides a spreadsheet screening approach for comparing costs of alternative pump-and-treat designs.
The purpose of the screening analysis is to quickly determine if significant cost savings might be achieved by
modifying an existing or planned pump-and-treat system, and to prioritize subsequent design efforts. The method is
demonstrated for three sites. Volume 1 is intended for a very broad audience.
Volume 2 describes the application of hydraulic optimization for improving pump-and-treat designs. Hydraulic
optimization combines groundwater flow simulation with linear and/or mixed-integer programming, to determine
the best well locations and well rates subject to site-specific constraints. The same three sites presented in Volume
1 are used to demonstrate the hydraulic optimization technology in Volume 2. Volume 2 is intended for a more
technical audience than Volume 1.
The author extends thanks to stakeholders associated with the following three sites, for providing information used
in this study:
Chemical Facility, Kentucky
Tooele Army Depot, Tooele, Utah
Offutt Air Force Base, Bellevue, Nebraska
At the request of the facility, the name of the Kentucky site is not specified in this report.
Information was provided for each site at a specific point in time, with the understanding that new information, if
subsequently gathered, would not be incorporated into this study. Updated information might include, for instance,
revisions to plume definition, remediation cost estimates, or groundwater models.
The author also extends thanks to Kathy Yager of the U.S. EPA Technology Innovation Office (TIO) and Dave
Burden of the U.S. EPA Subsurface Protection and Remediation Division (SPRD), for their support. Finally, the
author extends thanks to the participants of the three Stakeholder Workshops for providing constructive comments
during the course of the project.
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EXECUTIVE SUMMARY
The screening analysis presented in this report can be used to quickly determine if significant cost
savings may be achieved by altering key aspects of an existing or planned pump-and-treat system. The
spreadsheet-based screening analysis allows quick and inexpensive cost comparison of competing
alternatives at a site, in terms of Net Present Value (NPV). Site-specific values input to the spreadsheet
can be based on very detailed engineering calculations and modeling results, or may be based on
"ballpark estimates". The suggested approach includes a "checklist" of important site-specific factors to
evaluate, and requires the formulation of potential system modifications. System modifications may be
postulated with respect to the same goals as the present system, or with respect to modified goals.
The intended results are as follows:
• For alternatives that offer the potential of significant cost reduction, more detailed design
effort (e.g., flow or transport modeling, optimization modeling, technology evaluation,
etc.) is a high priority;
• For alternatives that offer little or no potential for cost reduction, more detailed design
effort (e.g., flow or transport modeling, optimization modeling, technology evaluation,
etc.) is a low priority.
The cost of a screening analysis at a site should be low relative to overall remediation costs (i.e., several
thousand dollars for most sites).
The screening approach was demonstrated for three sites with existing pump-and-treat systems. The
three sites can be summarized as follows:
Site
Kentucky
Tooele
Offutt
Existing
Pumping Rate
Moderate
High
Low
Cost
Pergpm
High
Low
Low
Potential Savings
from System
Modification
>$6M
>$3M
Little or None
Additional
Analysis
Merited?
Yes
Yes
No
Note: Potential savings represent millions of dollars, net present value (NPV), over 20 years
For Kentucky and Tooele, the screening analysis suggests that millions of dollars may be saved if
additional analysis is performed to reduce the total pumping rate (the potential savings incorporate the
additional Up-Front costs associated with additional analyses and system modification). Therefore,
additional analyses at these sites (modeling, optimization, engineering) are worthwhile. The additional
analyses would be performed to determine actual reductions in pumping rate that can be achieved, plus
detailed design efforts (if appropriate) for a modified system. For Offutt, the screening analysis suggests
that little or no savings is likely from a system modification, and additional analysis regarding system
modification at that site should be a low priority.
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This project was primarily focused on the reduction of pumping total pumping rate at pump-and-treat
sites (of course, other forms of optimization, such as the application of alternate treatment technologies,
may also provide significant benefits). Hydraulic optimization simulations were performed for each of
the three sites, to more rigorously determine the extent to which pumping rates (and associated costs)
might be reduced at each site. The results of the hydraulic optimization simulations are presented in
Volume 2 of this report.
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TABLE OF CONTENTS (Volume 1 of 2)
PREFACE i
EXECUTIVE SUMMARY ii
TABLE OF CONTENTS (Volume 1 of 2) iv
1.0 INTRODUCTION 1-1
1.1 PURPOSE OF PERFORMING A SCREENING ANALYSIS 1-1
1.2 CASE STUDY EXAMPLES 1-2
1.3 STRUCTURE OF THIS REPORT 1-3
2.0 OVERVIEW OF SPREADSHEET SCREENING APPROACH 2-1
2.1 COMPONENTS OF THE SPREADSHEET 2-1
2.2 SCREENING STEPS 2-2
3.0 IMPORTANT SITE-SPECIFIC FACTORS 3-1
3.1 POTENTIAL SAVINGS IN ANNUAL O&M 3-1
3.2 ANTICIPATED REMEDIATION TIMEFRAME 3-1
3.3 TARGET CONTAINMENT ZONE 3-2
3.4 CONTAINMENT VERSUS CLEANUP 3-3
3.5 STATUS OF GROUNDWATERMODELING 3-4
3.6 COSTS OF ADDITIONAL DESIGN AND SYSTEM MODIFICATION 3-5
3.7 HISTORICAL SYSTEM PERFORMANCE 3-5
3.8 POLITICAL/SOCIAL ISSUES 3-5
3.9 UNCERTAINTIES 3-5
4.0 CASE #1: KENTUCKY 4-
4.1 SITE BACKGROUND 4-
4.1.1 Site Location and Hydrogeology 4-
4.1.2 Plume Definition 4-
4.1.3 Existing Remediation System 4-
4.2 SCREENING ANALYSIS 4-2
4.2.1 Step 1: Organize Costs of Existing System (Baseline Scenario) 4-2
4.2.2 Step 2: Review Site-Specific Factors 4-2
4.2.3 Step 3: Formulate Alternative Scenarios 4-4
4.2.4 Step 4: Estimate Cost Components and Calculate Total Cost for Each Scenario 4-4
4.2.5 Step 5: Compare Total Cost of Each Alternate Scenario to Baseline Scenario 4-5
4.2.6 Step 6: Is Additional Analysis Merited? 4-5
5.0 CASE #2: TOOELE 5-
5.1 SITE BACKGROUND 5-
5.1.1 Site Location and Hydrogeology 5-
5.1.2 Plume Definition 5-
5.1.3 Existing Remediation System 5-
5.1.4 Groundwater Flow Model 5-2
5.2 SCREENING ANALYSIS 5-2
5.2.1 Step 1: Organize Costs of Existing System (Baseline Scenario) 5-2
5.2.2 Step 2: Review Site-Specific Factors 5-2
5.2.3 Step 3: Formulate Alternative Scenarios 5-4
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5.2.4 Step 4: Estimate Costs Components and Calculate Total Cost for Each Scenario
5.2.5 Step 5: Compare Total Cost of Each Alternate Scenario to Baseline Scenario . .
5.2.6 Step 6: Is Additional Analysis Merited?
6.0 CASE #3: OFFUTT
6.1 SITE BACKGROUND
6.1.1 Site Location and Hydrogeology
6.1.2 Plume Definition
6.1.3 Existing Remediation System
6.1.4 Groundwater Flow Model
6.2 SCREENING ANALYSIS
6.2.1 Step 1: Organize Costs of Existing System (Baseline Scenario)
6.2.2 Step 2: Review Site-Specific Factors
6.2.3 Step 3: Formulate Alternative Scenarios
6.2.4 Step 4: Estimate Costs Components and Calculate Total Cost for Each Scenario
6.2.5 Step 5: Compare Total Cost of Each Scenario to Baseline Scenario
6.2.6 Step 6: Is Additional Analysis Merited?
7.0 DISCUSSION AND CONCLUSIONS
8.0 REFERENCES AND DOCUMENTS PROVIDED BY SITES
5-4
5-5
5-5
6-1
6-1
6-1
6-1
6-1
6-2
6-2
6-2
6-3
6-3
6-4
6-5
6-5
7-1
8-1
List of Figures
Figure 4-1.
Figure 4-2.
Figure 4-3.
Figure 4-4.
Figure 5-1.
Figure 5-2.
Figure 5-3.
Figure 6-1.
Figure 6-2.
Figure 6-3.
List of Tables
Table 2-1.
Table 4-1.
Table 4-2.
Table 4-3.
Table 5-1.
Table 5-2.
Table 5-3.
Table 6-1.
Table 6-2.
Table 6-3.
Table 6-4.
Table 6-5.
Table 6-6.
Site location map, Kentucky.
Groundwater elevation contours, Kentucky.
EDC concentrations and current remediation wells, Kentucky.
Benzene concentrations and current remediation wells, Kentucky.
Site location map, Tooele.
Groundwater elevation contours, Tooele.
TCE concentrations and current remediation wells, Tooele.
Site location map, Offutt.
Groundwater elevation contours, Offutt.
Southern plume and current remediation wells, Offutt.
Format of the screening spreadsheet.
Current system, Kentucky.
Scenario 1, Kentucky: cut pumping by 33 percent, no new wells.
Scenario 2, Kentucky: cut pumping by 33 percent, five new wells.
Current system, Tooele.
Scenario 1, Tooele: cut pumping by 33 percent, no new wells.
Scenario 2, Tooele: cut pumping by 33 percent, five new wells.
Current system, Offutt: one new core well, 100 gpm at LF wells.
Scenario 1, Offutt: reduce toe well pumping by 33 percent, no additional toe wells.
Scenario 2, Offutt: reduce toe well pumping by 33 percent, two additional toe wells.
Scenario 3, Offutt: do not install new core well.
Scenario 4, Offutt: do not install new core well, two additional toe wells.
Scenario 5, Offutt: pumping at LF wells reduced fifty percent.
Appendix A: Sample calculations using different values for discount rate.
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1.0 INTRODUCTION
This report (Volume 1 of 2) presents a spreadsheet approach for comparing costs of alternative pump-
and-treat designs. The work presented herein was commissioned by the U.S. EPA Subsurface Protection
and Remediation Division (SPRD) and the U.S. EPA Technology Innovation Office (TIO).
1.1 PURPOSE OF PERFORMING A SCREENING ANALYSIS
The purpose of this screening analysis is to quickly determine if significant cost savings might be
achieved by altering key aspects of an existing or planned pump-and-treat system, and to prioritize
subsequent design efforts. Reasons for altering a pump-and-treat system design might include any or all
of the following:
potential to reduce the total cost;
potential to speed cleanup;
revised contaminant distribution; and
revised regulations and/or regulatory climate.
Design aspects to be considered for alteration might include:
total pumping rate;
locations of wells;
• number of wells;
projected cleanup time;
treatment technology employed;
remediation goal (cleanup versus containment); and
the target containment zone.
Typically there are many remediation scenarios to consider (e.g., containment only, containment plus
aggressive mass removal, containment of a smaller region, etc.), and many potential design options for
each of those scenarios (e.g., well locations, well rates, treatment technology, etc.).
The screening analysis allows quick and inexpensive cost comparison of competing alternatives. Total
costs (NPV) are estimated for each alternative, and compared to the total cost of a baseline system
(typically the existing system). The intended results of the screening analysis are as follows:
for alternatives that offer the potential of significant cost reduction, more detailed design
effort (e.g., flow or transport modeling, optimization modeling, technology evaluation,
etc.) is a high priority;
for alternatives that offer little or no potential for cost reduction, more detailed design
effort (e.g., flow or transport modeling, optimization modeling, technology evaluation,
etc.) is a low priority.
The results of the screening analysis provide a basis for prioritizing subsequent design activities. For
example:
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• if the screening analysis indicates that system costs are driven by total pumping rate, then
additional design effort may be focused on minimizing total pumping rate (e.g., hydraulic
optimization to minimize pumping required for containment);
• if the screening analysis indicates that system costs are driven by cleanup time (and
reduction in cleanup time is considered to be technically feasible), then additional design
effort may be focused on reducing cleanup time (e.g., evaluating options with aggressive
core zone pumping, and/or use of transport optimization);
• if the screening analysis indicates that system costs are driven by groundwater treatment
and/or discharge costs, and alternate technologies are potentially feasible, then additional
design effort may be focused on technology optimization (e.g., technology review, pilot
testing, etc.).
The results of the screening analysis can also be used to prioritize specific scenarios to consider during a
subsequent optimization analysis. For instance, the screening can compare estimated costs for scenarios
with and without the addition of new wells. If the screening analysis suggests that significant cost
reduction may be possible when no new wells are considered, but little cost reduction is likely when
costs of new wells are included, then the subsequent mathematical optimization analysis might only be
performed on the basis of existing well locations. On the other hand, if the screening analysis suggests
that significant cost reduction might be possible even when the costs of new equipment are considered,
then the mathematical optimization analysis might consider new well locations in addition to the existing
well locations.
Advantages of this screening approach are:
• it is easy to understand and apply;
• it is based on estimates of cost factors (which can be as simple as "ballpark estimates"),
and therefore can be applied very quickly and at little cost;
• it provides a simple and consistent framework for organizing cost data for pump-and-
treat systems; and
• it instigates the consideration of alternatives to existing pump-and-treat designs.
The spreadsheet tool is free, and is intended to be available via download from an EPA web site. The
cost of a screening analysis at a site should be low relative to overall remediation costs (i.e., several
thousand dollars for most sites).
1.2 CASE STUDY EXAMPLES
Three sites with existing pump-and-treat systems were evaluated in this study:
• Chemical Facility, Kentucky (hereafter called "Kentucky");
• Tooele Army Depot, Tooele, Utah (hereafter called "Tooele"); and
• Offutt Air Force Base, Bellevue, Nebraska (hereafter called "Offutt").
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A brief comparison of the three sites is provided below:
Pumping rate, current system (gpm)
Annual Operations & Maintenance
(O&M)
Type of treatment
Discharge of treated water
Most significant annual cost
Year system started
Cost of a new well
Flow model exists?
Transport model exists?
Kentucky
600
$1,800,000(1)
Steam Stripping
River
Steam
1992
$20,000
Yes
No
Tooele
7500
$1,800,000
Air Stripping
Reinjection
Electricity
1993
$300,000
Yes
Being Developed
Offutt
200
$122,000
POTW(2)
N/A
Discharge Fee
1996®
$40,000
Yes
Yes
(1) Does not include analytical costs.
(2) POTW stands for Publicly Owned Treatment Works.
(3) An interim system has operated since 1996, and a long-term system has been designed.
Three sites were included in this study to demonstrate differences in the application of the screening
approach that result from site-specific factors.
1.3
STRUCTURE OF THIS REPORT
The report is structured as follows:
Section 2: Overview of Spreadsheet Screening Approach
Section 3: Important Site-Specific Factors
Section 4: Case #1: Kentucky
Section 5: Case #2: Tooele
Section 6: Case #3: Offutt
Section 7: Discussion and Conclusions
Section 8: References
1-3
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2.0 OVERVIEW OF SPREADSHEET SCREENING APPROACH
2.1 COMPONENTS OF THE SPREADSHEET
Table 2-1 provides a spreadsheet-based framework for evaluating major costs components of apump-
and -treat system. Major costs items included in Table 2-1 are:
• annual O&M costs;
• the time horizon for each annual O&M item;
• costs of performing analyses associated with system improvement;
• costs of potential system modifications; and
• the discount rate (to calculate the NPV of future costs)
The table is further divided into two categories of costs:
• Up-Front costs
• Annual Costs
"Up-Front Costs" are input in present-day dollars. "Annual Costs" are also input in present-day dollars,
and a time horizon is specified in the column "# Years". The total amount of present-day dollars
resulting from annual values is calculated in the column "Total of Annual Costs", based on the time
horizon and the discount rate (the PV function available in Microsoft Excel was utilized, with the option
to calculate payments at the beginning of each year). In simple terms, the discount rate accounts for the
fact that money (if not spent today) can be invested at a rate greater than inflation, such that future
dollars have less value than present-day dollars (see Appendix A). The last column,"Total Costs",
combines the "Up-Front Costs" with the "Total of Annual Costs". This column represents the NPV of all
costs (i.e., expressed in present-day dollars).
The current value of a future costs is determined with the following relationship:
V, =
where:
v = annual cost per year, in present-day dollars
Vj = value of annual cost incurred during the/th year, in present-day dollars
D = discount rate (a percentage)
j = number of years (yrs) from present time
The actual discount rate (D) is a function of inflation, investment rates, and other opportunity costs
associated with present and future value of money. A full explanation of the discount rate is beyond the
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scope of this document. The reader is referred to Damodaran (1994) or Ross et. al. (1995) for a detailed
explanation. Complications can include formulating discount rate with or without inflation, change in
discount rate over time, change in annual costs over time, and others. For the simplified analyses
discussed herein, a discount rate between 3 and 8 percent will generally apply.
This screening spreadsheet is quite general with respect to range of application. Values input into the
spreadsheet can be based on very detailed engineering calculations and modeling results, or may be based
on "ballpark estimates". The spreadsheet can also be customized for specific sites. For instance,
additional rows can be added if a more detailed cost breakdown is desired.
It is important to remember that the cost calculations in Table 2-1 are highly dependant on the cost
estimates, time horizon, and discount rate. Those values are subject to uncertainty. Cost calculations can
be performed with different combinations of parameter values, to provide an evaluation of the sensitivity
of the results to those uncertainties.
2.2 SCREENING STEPS
To determine the potential benefits of system modifications, the following steps are suggested:
(1) compile and/or estimate cost components for a Baseline Scenario, and calculate Total
Cost for that scenario (the Baseline Scenario might be the current system, or might be the
current system design for a system not yet installed);
(2) review site-specific factors (evaluate which cost components are most significant, and
which cost components could be potentially reduced by a system modification);
(3) formulate alternate scenarios that have the potential to reduce costs;
(4) for each alternate scenario, estimate cost factors and calculate Total Cost;
(5) compare the Total Cost of each scenario to that of the Baseline Scenario;
(6) determine which scenarios (if any) merit further analysis (e.g., detailed design of well
locations and well rates, detailed evaluation of alternate treatment technologies, etc.).
A recommended approach for performing steps 1 through 3 is to arrange a phone call or meeting with a
team of individuals familiar with the site (e.g., site manager, site operator, regulator, site consultant,
groundwater modeler), to quickly compile cost data and identify potential scenarios for system
modification. For systems originally designed on the basis of trial-and-error groundwater flow modeling,
an estimated reduction in pumping rate of 10 to 40 percent may be anticipated if mathematical
optimization techniques are to be applied (Dr. Richard Peralta, personal communication, June 1999).
The next section of this report (Section 3) discusses site-specific factors that should be considered in
developing alternate scenarios and estimating cost factors for those scenarios. The spreadsheet screening
approach is then demonstrated for three existing sites (Sections 4, 5, and 6).
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3.0 IMPORTANT SITE-SPECIFIC FACTORS
Site-specific factors that impact management decisions for pump-and-treat designs include:
• potential savings in annual O&M;
• the projected remediation timeframe;
• the target containment zone;
• the remediation goal (containment versus cleanup);
• the status of groundwater modeling;
• the costs of additional design and system modification;
• the historical system performance;
• political/social issues; and
• uncertainties.
These factors can be thought of as a "checklist" when conducting a screening analysis. Each of these
site-specific factors is discussed below.
3.1 POTENTIAL SAVINGS IN ANNUAL O&M
Major components of annual O&M expenses for pump-and-treat systems typically include:
• electric (for operating well pumps, blowers, transfer pumps, etc.);
• material (carbon, chemicals for pretreatment, etc.);
• well/pump maintenance;
• water discharge fees, such as to a Publicly Owned Treatment Works (POTW);
• labor (monitoring, cleaning, reporting, system operation, etc.); and
• analytical.
Estimating reductions in annual O&M that might result from a system modification (e.g., reduced
pumping rate and/or reduced number of wells) can be quite complicated and site specific. At some sites
electricity associated with pumping water is the most significant cost. At some sites, the materials (e.g.,
granular activated carbon or chemical additions) are the most significant cost. At other sites, discharge
costs such as to POTW are most significant. At some sites the analytical costs may be the greatest
component of annual O&M, but the analytical costs may not be sensitive to modifications in system
design.
To utilize the screening spreadsheets, revised O&M costs must be estimated for alternate scenarios.
These estimates are site-specific. For instance, at some sites a specific reduction in total pumping rate
will yield annual savings of $10K or less, while at other sites the same reduction in total pumping will
yield annual savings of $1M or more. The cost estimates used in the spreadsheet analysis may be based
on historical site data, or may be "ballpark estimates".
3.2 ANTICIPATED REMEDIATION TIMEFRAME
System modification will generally result in greater benefits for projects with long remediation periods,
due to the cumulative nature of O&M cost savings with time. The cumulative savings due to a reduction
in annual O&M are far greater if the remediation timeframe is 20 yrs rather than 3 yrs. If cleanup is
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currently anticipated to last only a few months or years, system modifications are unlikely to yield
significant net benefits (unless existing O&M costs are extremely high).
Unfortunately, remediation timeframe is a very difficult design parameter to estimate. This is because
the site-specific factors affecting cleanup time are difficult to accurately characterize (due to presence of
NAPLs or other continuing sources, heterogeneities in the subsurface, dispersivity, etc.). Cleanup time
has historically been underestimated at many sites, even when sophisticated modeling techniques are
employed.
In some cases it is appropriate to define the remediation timeframe as "a very long time". For instance,
this may be the case if NAPLs are known to provide a continuing source of dissolved groundwater
contamination, or if contaminants strongly sorb onto solids. In such cases, the screening analysis should
utilize a time horizon of approximately 20 or 30 yrs (the same value should be used for all scenarios).
This is because the NPV of costs associated with expenditures beyond 20 or 30 yrs become less
significant, due to the time value of money. Also, assumptions regarding applicable technologies and/or
regulatory requirements beyond 20 or 30 yrs are subject to very significant uncertainty.
In cases where cleanup is considered feasible within 20 or 30 yrs, the screening analysis should utilize
the best available estimates. These estimates may be based on transport modeling, or may be simple
"ballpark estimates". Observed concentration trends are sometimes utilized to predict cleanup times, but
often these trends are non-linear and become asymptotic at low (yet unacceptable) contaminant levels
(Cohen et al., 1997). Some reasons for these phenomena are: (1) continuing (and sometimes undefined)
source areas; (2) time-limited desorption of contaminants; and (3) slow diffusion of contaminants from
low permeability areas.
If one alternative is considered likely to reduce cleanup time (relative to competing alternatives), that
should be reflected in the screening analysis by reducing the "# Years" for that scenario. The sensitivity
of screening results to different estimates of remediation timeframe can be easily assessed by assigning
different values within the spreadsheet.
3.3 TARGET CONTAINMENT ZONE
A design component of most pump-and-treat systems is to prevent the movement of contaminants beyond
a prescribed boundary, even if the primary remediation objective is cleanup. The volume of water to be
contained (the "target containment zone") may be defined by a property boundary, or by water quality
criteria such as the 5 part per billion (ppb) trichloroethene (TCE) contour. To evaluate if a specific
design is feasible, the target containment zone must be defined. Note that the target containment zone
may vary with depth if contaminant distribution varies with depth.
For some existing pump-and-treat systems, the target containment zone has not been formally defined.
For other systems, modifications to the target containment zone may be appropriate. If the plume has
expanded, or cleanup levels have become more strict, the target containment zone may need to be
increased in size. Alternatively, if the plume has contracted, or cleanup levels have been relaxed, the
target containment zone can be reduced in size.
In some cases, several alternatives for the target containment zone can be considered during the screening
analysis. For instance, one target containment zone may represent a current regulatory limit (e.g., 5-ppb
TCE contour) while an alternative target containment zone may represent a potential risk-based limit
(e.g., 20-ppb TCE contour). Potential cost reductions associated with the smaller target containment
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zone can be quantified with the screening spreadsheets. If the results indicate that potential savings
associated with a smaller target containment zone are significant, then those alternatives may merit
further consideration (within the context of potential regulatory requirements intended to protect human
health and the environment).
3.4 CONTAINMENT VERSUS CLEANUP
Existing pump-and-treat systems fall into one of three categories:
• containment: The main goal is to prevent further spreading of contaminants;
• cleanup: The main goal is reduction of contaminant concentrations below specific
cleanup levels (frequently in conjunction with containment or removal of contaminant
source areas); or
• hybrid: The main goal is containment, but cleanup may be possible and accelerated
mass removal is considered a benefit.
A "containment" goal is appropriate when there is a continuing source of groundwater contamination that
will prevent aquifer cleanup within any reasonable time frame, or when the contaminants cannot
effectively be removed from the aquifer. An example would be the presence of Dense Non-Aqueous
Phase Liquids (DNAPLs) below the water table, which are difficult to remove and provide a long-term
source of dissolved contamination. Containment may also be appropriate if the cost of cleanup is
prohibitively high relative to the cost of containment. Containment systems often consist of pumping
that is predominantly located at the downgradient portion (i.e., the "toe") of the target containment zone.
Sometimes reinjection wells are included downgradient of the pumping wells (to add hydraulic control),
or far upgradient of the pumping wells so that hydraulic control from the pumping wells is not
compromised.
A "cleanup" goal is appropriate when the source of groundwater contamination has been removed or
contained, and when contaminants can effectively be removed from the aquifer. Cleanup systems
generally consist of extraction wells located throughout the contaminated region, especially in highly
contaminated areas to maximize contaminant mass removal. Sometimes injection wells are added
upgradient of highly contaminated areas, to increase gradients towards the extraction wells and flush
contaminants through the aquifer.
A "hybrid" goal is appropriate when containment is of primary importance, but additional mass removal
is desired. In addition to pumping near the toe of the plume (for containment), one or more extraction
wells are placed in more highly contaminated areas, to remove additional mass. The concept is that
cleanup may be possible at the site, and therefore accelerated mass removal may provide a net benefit.
Unfortunately, cleanup of aquifers to regulatory levels is often difficult to achieve for a variety of
reasons, with "tailing" and "rebound" phenomena frequently observed (Cohen et al, 1997; NRC, 1994).
At many sites where cleanup is the goal, the estimated time frame required for cleanup is subject to
significant uncertainty. Historically, estimates of cleanup time have been overly optimistic.
The goal for a site (containment versus cleanup) significantly impacts the formulation of remedial
alternatives. If the goal is containment, minimizing total pumping required for containment will typically
minimize the remediation cost. If the goal is cleanup, there is a complex cost tradeoff associated with
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aggressive pumping (annual O&M costs are higher, but there is a potential for reduced remediation
timeframe).
For sites where a cleanup goal or hybrid goal has been employed, the screening spreadsheets can be used
to estimate potential savings from a switch to "containment-only". In this way, the potential benefits of
accelerated cleanup (from mid-plume and/or source area wells) can be evaluated against the additional
cost they require to operate.
3.5 STATUS OF GROUNDWATER MODELING
A primary component of many pump-and-treat designs is an "adequate" groundwater simulation model.
If a system modification will require additional groundwater modeling and/or optimization modeling to
implement (e.g., for detailed design), then estimated costs for those modeling efforts should be included
as "Up-Front" costs in the screening process. The costs of groundwater modeling and mathematical
optimization are site-specific, and are not easily generalized. They could range from $10K or less to
SlOOKormore.
Models represent simplifications of the aquifer system. They are based on imperfect input data, and are
subject to significant uncertainty. An "adequate" model, as defined here, is a site-specific simulator that
is accepted as a valid tool for evaluating aquifer responses as they relate to pump-and-treat alternatives.
The acceptance of the model is ideally based on a comparison of simulated versus observed conditions
under both pumping and non-pumping conditions (or multiple pumping conditions). Observed
conditions might include water levels, horizontal and/or vertical gradients (magnitude and direction),
gains or losses to streams, and contaminant distributions.
Two general classes of groundwater models are: (1) groundwater flow models; and (2) groundwater
transport models. For hydraulic optimization, a groundwater flow model is utilized for predictions of
water levels, drawdowns, gradients, and velocities, and also can be used as a basis for particle tracking
to illustrate groundwater flowpaths and capture zones. For transport optimization (which incorporates
contaminant concentrations and/or cleanup times) a solute transport model is required. Transport models
are generally more complicated than flow models, and require more input (initial plume distribution,
dispersion coefficients, sorption parameters, etc.). In addition, the predicted concentrations from a
groundwater transport model are subject to greater uncertainty than predictions of water levels from a
groundwater flow model.
If a site has not been previously modeled, the cost and time required to construct an "adequate"
groundwater model for conducting mathematical optimization must be considered. If modeling has
previously been performed, an evaluation should be made regarding the adequacy of the model for
making predictions. Issues that must be considered include: (1) is the type of model appropriate for the
desired analysis (i.e., a flow model is not appropriate if prediction of concentrations is required)? (2) is
the model accepted as a tool for comparing alternatives? (3) have aquifer stresses changed substantially
since the model was constructed (such as new pumping wells)? (4) is the model grid spacing sufficiently
small to analyze well capture zones? (5) are model boundaries sufficiently far from pumping wells? (6) is
model layering appropriate for the desired analysis? and (7) have model results been evaluated with
respect to observations during actual pumping conditions? If it is anticipated that revisions to the
existing model are required, the costs and time required for the revisions should be included.
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3.6 COSTS OF ADDITIONAL DESIGN AND SYSTEM MODIFICATION
When contemplating modifications to a pump-and-treat system, the costs of additional design and/or
system modifications should be considered. In addition to groundwater and/or optimization modeling
(discussed above), these may include: (1) engineering design; (2) regulatory negotiation; (3) field
implementation (i.e., installing new wells, piping, controls, pilot testing, and/or additional site
characterization); and (4) increased monitoring to assess the effects of system changes. For the screening
analysis, these costs should be estimated and included as "Up-Front Costs".
3.7 HISTORICAL SYSTEM PERFORMANCE
Historical performance of a pump-and-treat system can provide information that is pertinent for a
screening analysis. For instance: (1) O&M costs can be estimated with greater certainty on the basis of
historical data; (2) historical pumping rates and water levels can be used to evaluate if an existing
groundwater model reasonably predicts aquifer responses; (3) historical data may indicate problems that
tend to increase overall system costs (such as well clogging); and (4) observed reductions in contaminant
mass due to historical system performance may suggest the potential for large-scale strategy changes
(such as a reduction in the size of the target containment zone).
3.8 POLITICAL/SOCIAL ISSUES
It is important to consider a variety of political and/or social issues when formulating alternative
remediation scenarios. Some of these include:
• risks associated with system failure;
• likelihood of regulatory acceptance for a system modification;
• public perception and/or public relations;
• availability of funds for "Up-Front Costs"; and
• resistance to change (at many levels).
In some cases, alternatives that might reduce costs are nevertheless infeasible for one or more of these
reasons, and should probably be eliminated before the screening analysis is performed. Similarly, some
alternatives may be qualitatively preferable to others for one or more of these reasons, and those
"intangible" aspects should be considered when evaluating the results of the screening analysis (rather
than only comparing costs of competing alternatives).
3.9 UNCERTAINTIES
As previously discussed, the screening approach is based on many estimates (cost factors, remediation
timeframe, discount rate, etc.). Cost calculations with different combinations of these parameters should
be performed to evaluate the impacts of those uncertainties on screening results.
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4.0 CASE #1: KENTUCKY
4.1 SITE BACKGROUND
4.1.1 Site Location and Hydrogeology
The facility is located in, Kentucky, along the southern bank of a river (see Figure 4-1). There are in
excess of 200 monitoring points and/or piezometers at the site. The aquifer of concern is the uppermost
aquifer, called the Alluvial Aquifer. It is comprised of unconsolidated sand, gravel, and clay. The
Alluvial Aquifer has a saturated thickness of nearly 100 feet in the southern portion of the site, and a
saturated thickness of approximately 30 to 50 feet on the floodplain adjacent to the river. The decrease
in saturated thickness is due to a general rise in bedrock elevation (the base of the aquifer) and a decrease
in surface elevation near the floodplain. The hydraulic conductivity of the Alluvial Aquifer ranges from
approximately 4 to 75 ft/d.
Groundwater generally flows towards the river, where it is discharged (see Figure 4-2). However, a
groundwater divide has historically been observed between the site and other nearby wellfields (locations
of wellfields are illustrated on Figure 4-1). The groundwater divide is presumably caused by pumping at
the nearby wellfields.
4.1.2 Plume Definition
Groundwater monitoring indicates site-wide groundwater contamination. Two of the most common
contaminants, 1,2-dichloroethane (EDC) and benzene, are used as indicator parameters because they
are found at high concentrations relative to other parameters, and are associated with identifiable site
operations. Shallow plumes of EDC and benzene are presented in Figures 4-3 and 4-4, respectively.
Concentrations are very high, and the presence of residual NAPL contamination in the soil column is
likely (SVE systems have recently been installed to help remediate suspected source areas in the soil
column).
4.1.3 Existing Remediation System
A pump-and-treat system has been operating since 1992. Pumping well locations are illustrated on
Figures 4-3 and 4-4. There are three groups of wells:
BW wells: River Barrier Wells
SW wells: Source Wells
OW wells: Off-site Wells
The primary goal is containment at the BW wells, to prevent discharge of contaminated groundwater to
the river. The purpose of the SW wells is to accelerate mass removal. The purpose of the OW wells is
to prevent off-site migration of contaminants towards other wellfields. A summary of pumping rates is
as follows:
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BW wells:
Original Design
Current System
SW wells
OW wells
Total System:
Original Design
Current System
Number of Wells
18
23
8
8
34
39
Design Rate (gpm)
549
N/A
171
132
852
N/A
Typical Rate (gpm)
N/A
420-580
80-160
25-100
N/A
500-800
Five BW wells were added after the initial system was implemented, to enhance capture where
monitored water levels indicated the potential for gaps. The operating extraction rates are modified as
the river level rises and falls (when the river level falls, aquifer water levels also fall, and
transmissivity at some wells is significantly reduced). The eight OW wells controlling off-site plume
migration have largely remediated that problem, and will likely be phased out in the near future.
Contaminants are removed by steam stripping. The steam is purchased from operations at the site.
Treated water is discharged to the river. Site managers have indicated their desire for accelerated mass
removal, if it is not too costly. They do not favor significant reductions in pumping (and associated
annual costs) if that will result in longer cleanup times.
4.1.4 Groundwater Flow Model
An existing 2-dimensional, steady-state MODFLOW (McDonald and Harbaugh, 1988) model is a
simple representation of the system. There are 48 rows and 82 columns. Grid spacing near the river is
100 ft. The model has historically been used as a design tool, to simulate drawdowns and capture
zones (via particle tracking) resulting from specified pumping rates.
4.2 SCREENING ANALYSIS
4.2.1 Step 1: Organize Costs of Existing System (Baseline Scenario)
The current system has an annual O&M cost of approximately $1.8M/yr, excluding analytical costs.
Costs are summarized in Table 4-1, in the format of the screening spreadsheet. For this analysis, a
remediation timeframe horizon of 20 yrs is specified , to represent "a very long time". The total cost
(NPV) of the current system, for a 20-year time horizon, is estimated to be $23.55M (Table 4-1).
4.2.2 Step 2: Review Site-Specific Factors
Potential Reductions in Annual O&M. The steam cost ($ 1.2M/yr) is the most significant annual cost.
According to the site managers, the steam cost is essentially proportional to the pumping rate, such that
reductions in pumping rate would likely yield significant savings. Electrical cost ($200K/yr) and
materials cost associated with pH adjustment ($100K/yr) could also be reduced by a reduction in
pumping rate. Maintenance cost (50K/yr) and O&M labor cost ($250K/yr) would not be significantly
reduced by a reduction in pumping rate. Because steam is the most significant cost, a review of potential
alternate treatment technologies might also be worthwhile.
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Remediation Timeframe. Due to the likelihood of residual NAPL in the soil column, and the high levels
of contaminants in groundwater, it is likely that any alternatives to the current system considered will
have a remediation timeframe of more than 20 yrs. Therefore, using a consistent timeframe that
represents "a very long time" (e.g., 20 yrs) is appropriate.
Target Containment Zone. The priority of this system is to prevent discharge of contaminated water to
the River. A secondary target containment zone has historically been associated with off-site migration
of contaminants towards other wellfields, but a formal containment zone for that area has not been
reported, and the OW wells associated with that containment zone are planned to be phased out based on
observed concentration reductions.
Containment Versus Cleanup. The current system is a hybrid system, where containment is the primary
goal, but additional wells have been installed for accelerated mass removal (the SW wells). Site
managers have indicated their desire for accelerated mass removal, if it is not too costly. Therefore, it
may be appropriate to compare the current system to a "containment only" system, so that the
additional costs for accelerated mass removal can be quantified. In addition, the current SW wells may
not be ideally located with respect to maximum contaminant concentrations (based on updated plume
maps), and consideration of additional SW wells may be appropriate if accelerated mass removal
continues to be a goal.
Status of Groundwater Modeling. The current groundwater model is a simplified representation of the
hydrogeologic system. It is a useful tool for approximating drawdowns and capture zones. However, the
following are noted: (1) model grid spacing of 100 ft in the vicinity of the river permits only 1 or 2 cells
between some wells and the river, and a finer grid spacing would be better; (2) transient impacts
associated with changes in river level are not currently simulated by this steady-state model; (3) historical
pumping and water level data may provide an opportunity to verify predictions of the groundwater
model; and (4) the two-dimensionality of the model limits any ability to evaluate three-dimension aspects
of groundwater flow at the site.
Costs of Additional Analysis and System Modification. Because a reduction in pumping rate might
significantly reduce annual O&M costs, additional groundwater modeling and/or optimization modeling
may be considered to determine improved pumping rates. If the system is to be modified, costs
associated with engineering design and the regulatory process can also be anticipated. If new wells are to
be considered, the approximate cost (including associated piping) of new wells must be considered.
Ballpark estimates for these costs are:
additional flow modeling: $ 25,000
hydraulic optimization: $ 15,000
additional engineering design: $ 40,000
regulatory process: $ 25,000
additional wells: $ 20,000 per well
Historical System Performance. Based on concentration trends, the OW wells will likely be phased out
in the near future. Also, historical data suggest that when water level falls, production at some wells is
reduced (due to reduced aquifer transmissivity), and this is not accounted for by the groundwater flow
model.
Political/Social Issues. None identified.
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Uncertainties. Components of annual O&M costs are based on historical performance, so there is little
uncertainty in those values. There is also little uncertainty that the remediation timeframe for most (if
not all) scenarios will be 20 yrs or more. There are uncertainties (as always) in the discount rate and any
predictions made by the groundwater flow model.
4.2.3 Step 3: Formulate Alternative Scenarios
Two alternate scenarios were considered for this demonstration. In each scenario, it is assumed that a
reduction in pumping rate of 33 percent can be achieved in a modified system (from approximately 600
gpm to 400 gpm). A 33 percent reduction in flow rate could be accomplished in one or more of the
following ways:
• a reduction in rates at the BW wells required to maintain containment (via optimization);
• a reduction in pumping at the OW wells; and/or
• a reduction in pumping at the SW wells;
In Scenario 1, no new wells are assumed. In Scenario 2, the addition of up to 5 new wells are assumed
(i.e., possibly to improve the efficiency of containment, or possibly to improve the efficiency of mass
removal in highly contaminated areas).
For the purposes of this screening analysis, a potential reduction in pumping rate of 33 percent is a
reasonable goal. Of course, additional screening calculations could be performed with alternate values
for percent reduction, to assess the sensitivity of screening conclusions to the assumed reduction in total
pumping rate.
4.2.4 Step 4: Estimate Cost Components and Calculate Total Cost for Each Scenario
A spreadsheet analysis for each scenario is presented in Tables 4-2 and 4-3, respectively. The following
Up-Front costs are estimated for each alternate scenario:
$ 25K: improve the groundwater flow model
$ 15K: perform hydraulic optimization modeling
$ 40K: engineering design associated with a system modification
$ 25K: regulatory process associated with a system modification
For Scenario 2, an additional Up-Front cost is associated with the addition of new wells:
$ 1OOK: up to 5 new wells at $20K/well
The following reductions in annual O&M costs are estimated to result from a 33 percent reduction in
pumping rate, if it can be achieved:
steam: 33 percent reduction
electric: 20 percent reduction
materials: 33 percent reduction
maintenance: 0 percent reduction
O&M labor: 0 percent reduction
These estimates of cost reductions are based on the fact that steam cost is directly proportional to the
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volume of water treated, that electricity cost is a function of pumping rates at the wells, and materials
cost (associated with a pH adjustment) is directly proportional to the volume of water treated.
A 20-year time horizon is used for all scenarios.
4.2.5 Step 5: Compare Total Cost of Each Alternate Scenario to Baseline Scenario
Preliminary cost estimates for each alternate scenario are compared to the baseline scenario:
Baseline Scenario
Scenario #1
Scenario #2
Up-Front Costs
($)
$0
$105,000
$205,000
Sum of Annual
Costs
($NPV)
$23,553,578
$17,364,221
$17,364,221
Total Cost
($NPV)
$23,553,578
$17,469,221
$17,569,221
4.2.6 Step 6: Is Additional Analysis Merited?
The screening analysis suggests that significant savings might be achieved by modifying the pump-and-
treat system at the Kentucky facility, and therefore additional analysis is merited. The majority of
potential cost savings would be derived from a reduction in steam costs that would be associated with a
potentially reduced pumping rate. The assumed pumping rate reduction of 33 percent may or may not be
achievable. However, the screening analysis suggest that performing additional analyses (e.g. modeling,
mathematical optimization, engineering design) in an attempt to reduce the pumping rate has the potential
to yield savings of millions of dollars (NPV) over a 20 year period, and therefore is worthwhile.
Similarly, if pumping rates can be reduced by switching to a "containment-only" system, net savings of
millions of dollars might results, and consideration of that alternative is also suggested.
The screening results for Scenario 2 indicate that the Up-Front cost associated with five additional wells
is small, relative to potential savings afforded by a significant reduction in pumping rates. This suggests
that additional well locations should be considered if it is thought that those wells may lead to an overall
reduction in total pumping. Similarly, it indicates that if pumping rates required for containment (e.g., at
the BW wells) can be substantially reduced, the long-term savings will more than offset the cost of
installing additional wells in the most highly contaminated areas, for the purpose of increased mass
removal.
The cost factors used in the spreadsheet screening method are all estimates. However, an uncertainty
analysis can be performed to assess the sensitivity of screening results to different cost estimates. For this
site, modifying the discount rate or time horizon will not change the overall conclusions. Increasing the
Up-Front cost estimates (modeling, engineering, etc.) by a factor of two or five will not change the
overall conclusions. Similarly, a different assumption for achievable reduction in pumping that might
result from additional analysis and/or a switch to a containment only system (e.g., 20 percent rather than
33 percent) will also not change the overall conclusions. Therefore, these uncertainties do not change the
conclusion that additional analysis regarding system modification is merited at this site.
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5.0 CASE #2: TOOELE
5.1 SITE BACKGROUND
5.1.1 Site Location and Hydrogeology
The facility is located in Tooele Valley in Utah, several miles south of the Great Salt Lake, (see Figure 5-
1). The aquifer of concern generally consists of alluvial deposits. However, there is an uplifted bedrock
block at the site where groundwater is forced to flow from the alluvial deposits into fractured and
weathered rock (bedrock), and then back into alluvial deposits.
The unconsolidated alluvial deposits are coarse grained, consisting of poorly sorted clayey and silty sand,
gravel, and cobbles eroded from surrounding mountain ranges. There are several fine-grained layers
assumed to be areally extensive but discontinuous, and these fine-grained layers cause vertical head
differences between adjacent water-bearing zones. Bedrock that underlies these alluvial deposits is as
deep as 400 to 700 feet. However, in the vicinity of the uplifted bedrock block, depth to bedrock is
shallower, and in some locations the bedrock is exposed at the surface.
Depth to groundwater ranges from 150 to 300 ft. The hydraulic conductivity of the alluvium varies from
approximately 0.13 to 700 ft/day, with a representative value of approximately 200 ft/day. In the
bedrock, hydraulic conductivity ranges from approximately 0.25 ft/day in quartzite with clay-filled
fractures to approximately 270 ft/day in orthoquartzite with open, interconnected fractures.
Groundwater generally flows to the north or northwest, towards the Great Salt Lake (see Figure 5-2).
Recharge is mostly derived from upgradient areas (south of the facility), with little recharge from
precipitation. Gradients are very shallow where the water table is within in the alluvial deposits. There
are steep gradients where groundwater enters and exits the bedrock block, and modest gradients within
the bedrock block. There is more than 100 ft of head difference across the uplifted bedrock block. This
suggests that the uplifted bedrock area provides significant resistance to groundwater flow. North (i.e.,
downgradient) of the uplifted bedrock block, the vertical gradient is generally upward.
5.1.2 Plume Definition
The specific plume evaluated in this study originates from an industrial area in the southeastern corner of
the facility, where former operations (since 1942) included handling, use, and storage of TCE and other
organic chemicals. Groundwater monitoring indicates that the primary contaminant is TCE, although
other organic contaminants have been detected. TCE concentrations in the shallow (model layer 1) and
deep (model layer 2) portions of the aquifer are presented on Figure 5-2. Concentrations are significantly
lower in the deeper portions of the aquifer than in shallow portions of the aquifer. Also, the extents of
the shallow and deep plumes do not directly align, indicating a complex pattern of contaminant sources
and groundwater flow. Continuing sources of dissolved contamination are believed to exist.
5.1.3 Existing Remediation System
A pump-and-treat system has been operating since 1993. The system consists of 16 extraction wells and
13 injection wells (see Figure 5-3 for well locations). An air-stripping plant, located in the center of the
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plume, is capable of treating 8000 gpm of water. It consists of two blowers operated in parallel, each
capable of treating 4000 gpm. Sodium hexametaphosphate is added to the water prior to treatment, to
prevent fouling of the air stripping equipment and the injection wells. Treated water is discharged via
gravity to the injection wells.
Based on the well locations and previous plume delineations, the original design was for cleanup. At the
time the system was installed, the source area was assumed to be north of the industrial area (near a
former industrial waste lagoon). Subsequently, it was determined that the source area extended far to the
south (in the industrial area). As a result, the current system essentially functions as a containment
system (there are no extraction wells in the area of greatest contaminant concentration).
Historically, the target containment zone has been defined by the 5-ppb TCE contour. Given the current
well locations, anticipated cleanup time is "a very long time". However, a revised (i.e., smaller) target
containment zone is now being considered, based on risks to potential receptors. A revised target
containment zone might correspond to the 20-ppb or 50-ppb TCE contour.
5.1.4 Groundwater Flow Model
A three-dimensional, steady-state MODFLOW model was originally constructed in 1993 (subsequent to
the design of the original system), and has been recalibrated on several occasions (to both non-pumping
and pumping conditions). The current model has 3 layers, 165 rows, and 99 columns. Cell size is 200 ft
by 200 ft. Model layers were developed to account for different well screen intervals, as follows:
Layer 1: 0 to 150 ft below water table
Layer 2: 150to300ft below water table
Layer 3: 300 to 600 ft below water table
Boundaries include general head conditions up- and down-gradient, no flow at the sides and the bottom.
The model has historically been used as a design tool, to simulate drawdowns and capture zones (via
particle tracking) that result from specified pumping and injection rates.
5.2 SCREENING ANALYSIS
5.2.1 Step 1: Organize Costs of Existing System (Baseline Scenario)
The current system has an annual O&M cost of approximately $1.8M/yr. Costs are summarized in Table
5-1, in the format of the screening spreadsheet. For this analysis, a remediation timeframe horizon of 20
yrs is specified , to represent "a very long time". The total cost (NPV) of the current system, for a 20-
year time horizon, is estimated to be S23.68M (Table 5-1).
5.2.2 Step 2: Review Site-Specific Factors
Potential Reductions in Annual O&M. The most significant cost is the electric cost, which is
approximately $1.0M/yr. According to the site managers, the electric cost is driven by the cost of
extracting water and delivering it to the treatment plant. A reduction in pumping rate would therefore
reduce electrical costs. Also, if pumping rate is reduced below 4000 gpm, an additional savings in
electricity could result by shutting down one of the two blowers. Sodium hexametaphosphate cost
($200K/yr) is directly proportional to pumping rate. Maintenance cost (30K/yr) and O&M labor cost
($500K/yr) may or may not be significantly reduced by a reduction in pumping rate. Analytical costs
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($80K/yr) would not likely be impacted by a reduction in pumping rate.
Remediation Timeframe. It is likely that any system limited to the existing well network will have a
remediation timeframe of more than 20 yrs. This is because there is a continuing source of dissolved
groundwater contamination, and the current wells do not provide source control. Therefore, using a
timeframe that represents "a very long time" (e.g., 20 yrs) for scenarios limited to the existing wells is
appropriate. However, for scenarios with the addition of new wells near the source area, use of a 20-year
time horizon may be conservative. This is because containment of the source area could eventually allow
most or all of the existing wells to be shut off (i.e., O&M costs associated with some wells might be
incurred for significantly less than 20 yrs).
Target Containment Zone. Historically, the target containment zone has been defined by the 5 ppb TCE
contour. However, a smaller target containment zone (based on risk to potential receptors) is being
considered. A revised target containment zone might correspond to the 20 ppb or 50 ppb TCE contour,
rather than the 5 ppb TCE contour. The target containment zone varies with depth. The target
containment zone in the deeper portion of the aquifer is significantly smaller than in the shallow aquifer.
Containment versus Cleanup. Based on the well design, the original goal was cleanup, assuming a source
area north of the industrial area. Subsequently, it was determined that the source area extends south to
the industrial area, and therefore the current system functions essentially as a containment system (there
are no extraction wells in the area of greatest contaminant concentration). Presumably, cleanup is still a
long-term goal at this site, since concentrations are relatively low.
Status of Groundwater Modeling. The current groundwater model is a useful tool for approximating
drawdowns and capture zones. However, the following are noted: (1) near the source area, simulated
flow directions are not consistent with the shape of the observed plume; and (2) the bedrock block is a
very complex feature, and accurate simulation of that feature is very difficult.
Costs of Additional Analysis and System Modification. Because a reduction in pumping rate would
significantly reduce annual O&M costs, additional groundwater modeling and/or optimization
modeling may be considered to optimize pumping rates. Because cleanup is possible at this site if the
source area is contained, solute transport modeling and/or transport optimization may also be
considered. If the system is to be modified, costs associated with engineering design and the regulatory
process can also be anticipated. If new wells are to be considered, the approximate cost should be
included. Ballpark estimates for these costs are:
additional flow modeling: $ 10,000
transport mode ling: $ 30,000
optimization (hydraulic or transport): $ 25,000
additional engineering design: $ 40,000
regulatory process: $ 45,000
additional wells: $300,000 per well.
Historical System Performance. The toe of the plume has contracted since the system was installed,
and well E-12 has been shut off as a result. This is likely the result of mass removal provided by wells
upgradient of E-12, which extract a very significant amount of water.
Political/Social Issues. There a no receptors immediately downgradient of the plume, so risks
associated with failure of a containment system are lower than at many other sites.
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Uncertainties. Components of annual O&M costs are based on historical performance, so there is little
uncertainty in those values. There are uncertainties (as always) in the discount rate and any
predictions made by the ground-water flow model.
5.2.3 Step 3: Formulate Alternative Scenarios
Two alternate scenarios were considered for this demonstration. In each scenario, it is assumed that a
reduction in pumping rate of 33 percent can be achieved in a modified system (from approximately 7500
gpm to 5000 gpm). This could be accomplished by:
• optimizing rates to achieve more efficient containment of the 5-ppb plume; and/or
• reducing the size of the target containment zone (if independently demonstrated to
maintain protection of human health and the environment).
In Scenario 1, no new wells are assumed. In Scenario 2, the addition of up to 5 new wells are assumed
(i.e., possibly to improve the efficiency of containment, or possibly to improve the efficiency of mass
removal in highly contaminated areas).
For the purposes of this screening analysis, a potential reduction in pumping rate of 33 percent is a
reasonable goal. Of course, additional screening calculations could be performed with alternate values
for percent reduction, to assess the sensitivity of screening conclusions to the assumed reduction in total
pumping rate.
5.2.4 Step 4: Estimate Costs Components and Calculate Total Cost for Each Scenario
A spreadsheet analysis for each scenario is presented in Tables 5-2 and 5-3, respectively. The following
Up-Front costs are estimated for each alternate scenario:
$ 10K: improve the groundwater flow model
$ 30K: perform transport modeling
$ 25K: perform optimization modeling (hydraulic or transport)
$ 40K: engineering design associated with a system modification
$ 40K: regulatory process associated with a system modification
For Scenario 2, an additional Up-Front cost is associated with the addition of new wells:
$1.5M: up to 5 new wells at $300K/well
The following reductions in annual O&M costs are estimated to result from a 33 percent reduction in
pumping rate, if it can be achieved:
electric: 20 percent reduction
materials: 33 percent reduction
maintenance: 0 percent reduction
O&M labor: 0 percent reduction
analytical 0 percent reduction
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These estimates of cost reduction are based on the fact that electricity cost is a function of pumping
rates at the wells, and materials cost (associated with addition of sodium hexametaphosphate to prevent
clogging) is directly proportional to the volume of water treated.
A 20 year time horizon is used for each scenario. As previously discussed, this may be conservative if
additional well are added in the source area, because the addition of source control may allow some
existing wells to be turned off in less than 20 yrs.
5.2.5 Step 5: Compare Total Cost of Each Alternate Scenario to Baseline Scenario
Preliminary cost estimates for each alternate scenario are compared to the baseline scenario:
Baseline Scenario
Scenario #1
Scenario #2
Up-Front Costs
($)
$0
$145,000
$1,645,000
Sum of Annual
Costs
($NPV)
$23,684,431
$20,195,007
$20,195,007
Total Cost
($NPV)
$23,684,431
$20,340,007
$21,840,007
5.2.6 Step 6: Is Additional Analysis Merited?
The screening analysis for Scenario 1 suggests that significant savings might be achieved by modifying
the pump-and-treat system at Tooele, and therefore additional analysis is merited. The majority of
potential cost savings would be derived from a reduction in electrical costs that would be associated with
a reduced pumping rate. The assumed pumping rate reduction of 33 percent may or may not be
achievable. However, the screening analysis suggest that performing additional analyses (e.g. modeling,
mathematical optimization, engineering design) to reduce the pumping rate has the potential to yield
savings of millions of dollars (NPV) over a 20 year period, and therefore is worthwhile.
The screening results for Scenario 2 indicates that additional well locations, even at a cost of
$300K/well, should be considered if it is thought that those wells may lead to an overall reduction in total
pumping. This is because nearly $2M of potential savings are indicated, even when the costs of up to
five new wells are included.
The cost factors used in the spreadsheet screening method are all estimates. However, an uncertainty
analysis can be performed to assess the sensitivity of screening results to different cost estimates. For
this site, modifying the discount rate will not change the overall conclusions. Similarly, reducing the
timeframe for all scenarios (e.g., from 20 to 10 yrs) will not change the overall conclusions, although the
potential savings indicated for Scenario 2 will be reduced (because the high cost of adding new wells will
be offset by fewer years of savings in annual O&M). Increasing the Up-Front cost estimates (modeling,
engineering, etc.) by a factor of two or five will not change the overall conclusions. A different
assumption for achievable reduction in pumping (i.e., less than 33 percent) might change the overall
conclusions. However, given the extremely high rate of pumping at this site, and the potential for
reducing the size of the target containment zone, it may be possible to reduce pumping rates by more
than 33 percent. Therefore, these uncertainties do not change the conclusion that additional analysis
regarding system modification is merited at this site.
5-5
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6.0 CASE #3: OFFUTT
6.1 SITE BACKGROUND
6.1.1 Site Location and Hydrogeology
The facility is located in Sarpy County, Nebraska, next to the City of Bellevue (see Figure 6-1). The
specific plume evaluated in this study is in the Southern Plume within the Hardfill 2 (HF2) Composite
Site at Offutt. The principal aquifer at the site consists of unconsolidated sediments resting on bedrock.
The aquifer system is heterogeneous and complex. Groundwater flows easterly and southeasterly (see
Figure 6-2). Depth to groundwater is generally 5 to 20 ft. The hydraulic conductivity of the alluvium
varies significantly with location and depth, due the complex stratigraphy.
6.1.2 Plume Definition
Groundwater monitoring indicates that the primary contaminants are chlorinated aliphatic hydrocarbons
(CAH's) including TCE, 1,2-dichloroethene (1,2-DCE), and vinyl chloride. Releases (initially as TCE)
formed localized vadose zone and dissolved groundwater plumes. Subsequent groundwater transport
from these multiple sources has resulted in groundwater contamination in shallow and deeper portions of
the Alluvial Aquifer.
The extent of the Southern Plume is illustrated on Figure 6-3. The core zones are defined as follows:
• shallow zone: upper 20 ft of saturated zone
• shallow-intermediate zone: from 930 ft MSL to 20 ft below water table
intermediate zone: 910 ft MSL to 930 ft MSL
• deep zone: below 910 ft MSL
The Southern Plume is approximately 2400 ft long, and extends just beyond the southern site boundary.
6.1.3 Existing Remediation System
An interim remediation system is in place, and consists of three wells (see Figure 6-3), pumping a total of
150 gpm:
• one "Toe Well" that is located within the southern plume, at 50 gpm; and
• two wells downgradient of the plume (the "LF wells"), at 100 gpm combined.
The extracted water is discharged to a POTW.
The two LF wells are associated with a landfill located downgradient from the Southern Plume boundary.
The LF wells are considered part of the interim system, because they provide a degree of ultimate
containment for the plume. However, allowing the plume to spread towards the LF wells is considered to
be a negative long-term result.
To prevent further spreading of the Southern Plume, a long term pump-and-treat system has been
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designed, with the addition of a "Core Well" within the southern plume (see Figure 6-3). The design of
the long-term system calls for 200 gpm total, as follows:
• one Toe well that is located within the southern plume, at 50 gpm;
• one Core well that is located within the southern plume, at 50 gpm; and
• two wells downgradient of the plume (the "LF wells"), at 100 gpm combined.
The intent is for the Toe well and Core well to prevent the Southern Plume from spreading beyond it's
present extent (rather than allowing the plume to flow towards the LF wells), and also to more effectively
contain the source areas (because the core well is located immediately downgradient from the source
areas). Under this scenario, the LF wells are not actually providing containment or cleanup for the
Southern Plume (in fact, pumping at the LF wells negatively impacts containment of the Southern
Plume). The original purpose of the LF wells is not related to remediation of the Southern Plume, and it
is hoped that pumping at the LF wells may be reduced (or even terminated) in the future.
6.1.4 Groundwater Flow Model
A three-dimensional, steady-state MODFLOW model was originally constructed in 1996. In addition, a
solute transport model was created with the MT3D code (Zheng, 1990). The groundwater models were
used to simulate various groundwater extraction scenarios. The current model has 6 layers, 77 rows, and
140 columns. Cell size varies from 25 by 25 ft to 200 x 200 ft. Layer 4 represents an alluvial sand layer,
and that layer has historically been evaluated with particle tracking to determine if containment is
achieved under a specific pumping scenario.
The solute transport model indicates the following:
• under the interim system, pumping will be required for more than 20 yrs to maintain
containment (due to the continuing source), and concentrations near the site boundary
will be reduced to MCL levels within 10 to 20 yrs;
• under the long-term design, pumping will be required at the Core well for more than 20
yrs to maintain containment (due to the continuing source), but cleanup of the area
downgradient of the core well will be achieved in less than 10 yrs.
In each case, some component of pumping is anticipated for "a very long time", due to continuing
sources.
6.2 SCREENING ANALYSIS
6.2.1 Step 1: Organize Costs of Existing System (Baseline Scenario)
For this analysis, the baseline system is the currently designed system. That system has an annual O&M
cost of approximately $122,000. Costs are summarized in Table 6-1, in the format of the screening
spreadsheet. For this analysis, a remediation timeframe of 20 yrs is used, to represent "a very long time".
However, based on the previous solute transport model results for the baseline system, it is assumed that
the Toe well may be shut off in 10 yrs, so a 10-year time horizon is specified for discharge fees
associated with the Toe Well. The total cost (NPV) of the current system, for a 20-year time horizon, is
estimated to be $1.58M (Table 6-1).
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6.2.2 Step 2: Review Site-Specific Factors
Potential Reductions in Annual O&M. The most significant cost for this system is associated with
discharge of pumped water to the POTW, which costs approximately $400 per gpm per year. Reducing
the pumping will reduce the discharge fees proportionately. With the exception of discharge costs, no
other cost component would be substantially reduced by reducing the pumping rate.
Remediation Timeframe. It is anticipated that pumping will be required for "a very long time" to maintain
containment of the source area. It is expected that pumping at the Core well will effectively contain the
source area, allowing the Toe well to be turned off within 10 yrs.
Target Containment Zone. The primary goal is to prevent additional spreading of the Southern Plume.
An additional goal of the long-term system is containment of the source areas, which will promote
cleanup of the plume downgradient of the Core Well.
Containment versus Cleanup. Full cleanup is not currently anticipated. This is primarily a containment
system. However, the addition of a Core well in the long-term design promotes cleanup of the plume
downgradient of the Core Well, by effectively containing the source areas.
Status of'Ground-water Modeling. The current groundwater flow model is a useful tool for
approximating drawdowns and capture zones. A transport model has already been developed and
applied.
Costs of Additional Analysis and System Modification. If optimization modeling is to be performed in
an attempt to reduce total pumping, costs associated with optimization must be considered. If a system
without the Core well is considered (i.e., containment of the Southern Plume by pumping only near the
toe of the plume), the "Up-Front" cost of the Core well can be removed (approximately $40K). If new
wells are to be considered, the approximate cost is estimated at $40K/well.
Historical System Performance. A full system (including the core well) has not yet been implemented.
Political/Social Issues. None identified.
Uncertainties. Components of annual O&M costs are straightforward, and there is little uncertainty in
those values. There are uncertainties (as always) in the discount rate and any predictions made by the
groundwater flow model. The cleanup time predictions made with the solute transport code are subject
to significant uncertainty.
6.2.3 Step 3: Formulate Alternative Scenarios
Five alternate scenarios were considered for this demonstration:
Scenario 1: Reduce Toe well pumping by 33% while maintaining containment at the plume
toe, and design rates of 50 gpm at the Core well and 100 gpm combined at the
LF wells;
Scenario 2: Same as Scenario 1, but consider addition of up to 2 new wells near the toe of
the plume;
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Scenario 3: No core well, increase pumping at the Toe well from 50 gpm to 75 gpm to
maintain containment at the Plume toe, and design rate of 100 gpm combined at
the LF wells;
Scenario 4: Same as Scenario 3, but consider up to 2 additional wells near the toe of the
plume;
Scenario 5: Same as baseline scenario, but cut pumping at the LF wells by half.
6.2.4 Step 4: Estimate Costs Components and Calculate Total Cost for Each Scenario
A spreadsheet analysis for each scenario is presented in Tables 6-2 through 6-6. Estimated Up-Front
costs, and estimated changes in annual O&M costs, are presented below for each scenario.
Scenario 1: reduce pumping at toe by 33 percent, no additional wells
Up Front Costs:
$ 15K: additional transport modeling
$ 15K: perform optimization modeling (hydraulic or transport)
$ 47K: fixed construction for all scenarios (transition from interim system)
$ 20K: regulatory process associated with a system modification
$ 40K: new core well
O&M Costs:
discharge fee: 33 percent reduction for toe well, over 10 yrs
Scenario 2: reduce pumping at toe by 33 percent. 2 new toe wells
Same as scenario 1, but add $80K in Up-Front costs (2 additional new wells at $40K/well)
Scenario 3: do not install core well (save 50 gpm). increase toe well from 50 to 75 gpm. no new toe wells
Up Front Costs:
$ 15K: additional transport modeling
$ 15K: perform optimization modeling (hydraulic or transport)
$ 47K: fixed construction for all scenarios (transition from interim system)
$ 20K: regulatory process associated with a system modification
O&M Costs:
discharge fee: 50 percent increase for toe well (50 -> 75 gpm), over 20 yrs
discharge fee: 33 percent reduction for other wells (150 -> 100 gpm), over 20 yrs
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Based on the transport modeling previously performed, the remediation timeframe associated with the
toe well is increased from 10 yrs to 20 yrs for this scenario, because there is no longer a core well to
provide effective containment of the source area.
Scenario 4: do not install core well (save 50 gpm). increase toe well from 50 to 75 gpm. 2 new toe wells
Same as scenario 3, but add $80K in Up-Front costs (2 additional new wells at $40K/well)
Scenario 5: cut pumping at LF wells from 100 to 50 gpm
Up Front Costs:
$ 15K: additional transport modeling
$ 47K: fixed construction for all scenarios (transition from interim system)
$ 20K: regulatory process associated with a system modification
$ 40K: new core well
O&M Costs:
discharge fee: 33 percent reduction for non-toe wells (150 -> 100 gpm), over 20 yrs
6.2.5 Step 5: Compare Total Cost of Each Scenario to Baseline Scenario
Preliminary cost estimates for each alternate scenario are compared to the baseline scenario:
Baseline Scenario
Scenario #1
Scenario #2
Scenario #3
Scenario #4
Scenario #5
Up-Front Costs
($)
$87,000
$137,000
$217,000
$97,000
$177,000
$122,000
Sum of Annual
Costs
($NPV)
$1,496,859
$1,442,804
$1,442,804
$1,465,556
$1,465,556
$1,235,153
Total Cost
($NPV)
$1,583,859
$1,579,804
$1,659,804
$1,562,556
$1,642,556
$1,357,153
6.2.6 Step 6: Is Additional Analysis Merited?
The screening analysis suggests that little savings are likely to be achieved by modifying the pump-and-
treat system at Offutt. The most promising modification (Scenario 5) is based on a reduction of pumping
at the downgradient LF wells, which are not specifically managed with respect to the Southern Plume.
Scenarios 1 through 4, which pertain to management of the wells within the Southern Plume, offer less
promise for cost reduction.
6-5
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The reason that this system offers little promise for cost reduction is that there is a low total pumping
rate, and a relatively low treatment cost. Therefore, little total savings can be generated by reducing the
pumping rate (even by as much as 33 percent). The Up-Front costs associated with modifying the system
will not be justified by the minimal annual savings that might result. Therefore, additional analysis at
this site (with respect to system modification) is a low priority.
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7.0 DISCUSSION AND CONCLUSIONS
The screening analysis presented in this report can be used to quickly determine if significant cost
savings may be achieved by altering key aspects of an existing or planned pump-and-treat system. The
spreadsheet-based screening analysis allows quick and inexpensive cost comparison of competing
alternatives at a site, in terms of Net Present Value (NPV). Site-specific values input into the
spreadsheet can be based on very detailed engineering calculations and modeling results, or may be based
on "ballpark estimates". The suggested approach includes a "checklist" of important site-specific factors
to evaluate, and requires the formulation of potential system modifications. System modifications may
be postulated with respect to the same goals as the present system, or with respect to modified goals.
The intended results are as follows:
• For alternatives that offer the potential of significant cost reduction, more detailed design
effort (e.g., flow or transport modeling, optimization modeling, technology evaluation,
etc.) is a high priority;
• For alternatives that offer little or no potential for cost reduction, more detailed design
effort (e.g., flow or transport modeling, optimization modeling, technology evaluation,
etc.) is a low priority.
The cost of a screening analysis at a site should be low relative to overall remediation costs (i.e., several
thousand dollars for most sites).
The spreadsheet screening approach was demonstrated for three sites with existing pump-and-treat
systems. The three sites can be summarized as follows:
Site
Kentucky
Tooele
Offutt
Existing
Pumping Rate
Moderate
High
Low
Cost
Pergpm
High
Low
Low
Potential Savings
from System
Modification
>$6M
>$3M
Little or None
Additional
Analysis
Merited?
Yes
Yes
No
Note: Potential savings represent millions of dollars, net present value (NPV), over 20 years
For Kentucky and Tooele, the screening analysis suggests that millions of dollars may be saved if
additional analysis is performed to reduce the total pumping rate (the potential savings incorporate the
additional Up-Front costs associated with additional analyses and system modification). Therefore,
additional analyses at these sites (modeling, optimization, engineering) are worthwhile. The additional
analyses would be performed to determine actual reductions in pumping rate that can be achieved, plus
detailed design efforts (if appropriate) for a modified system. For Offutt, the screening analysis suggests
that little or no savings is likely from a system modification, and additional analysis regarding system
modification at that site should be a low priority.
7-1
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This project was primarily focused on the reduction of pumping total pumping rate at pump-and-treat
sites (of course, other forms of optimization, such as the application of alternate treatment technologies,
may also provide significant benefits). Hydraulic optimization simulations were performed for each of
the three sites, to more rigorously determine the extent to which pumping rates (and associated costs)
might be reduced at each site. The results of the hydraulic optimization simulations are presented in
Volume 2 of this report.
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8.0 REFERENCES AND DOCUMENTS PROVIDED BY SITES
Cohen, R.M., J.W. Mercer, R.M. Greenwald, and M.S. Beljin, 1997. Design Guidelines for
Conventional Pump-and-Treat Systems, U.S.EPA Ground Water Issue Paper, EPA/540/S-97/504.
Damodaran, Aswath, 1994. Damodaran on Valuation, John Wiley & Sons.
Dames & Moore, 1997. Plantwide Corrective Action Program, Evaluation of Effectiveness, Second Half
1997, Kentucky Site (December 30, 1997).
Dames & Moore (date unknown). IsoconcentrationMaps, September 1996 (Draft).
Kleinfelder, Inc. 1998. Draft, Southeastern Boundary Groundwater Investigation, Report of Findings,
Tooele Army Depot (TEAD, Tooele, Utah, Volume I (Draft Report, February 13, 1998).
McDonald, M.G., and A.W. Harbaugh, 1988. A modular three-dimensional finite-difference
groundwater flow model, U.S. Geological Survey, Techniques of Water-Resources Investigations, Book
6, Chapter Al.
NRC, 1994. Alternatives for Groundwater Cleanup. National Research Council, National Academy
Press.
Ross, Stephen A., Randolf W. Westerfield, and Bradford D. Jordan, 1995. Fundamentals of Corporate
Finance, 3rd edition, Irwin Publishing.
Woodward-Clyde, 1997. Draft Feasibility Study, Hardfill 2 Composite Site (SS-40), Offutt Air Force
Base, Nebraska (Draft Report, August 28, 1997)
Woodward Clyde, 1998. Pre-Draft, Pump Cycling Report, Landfill 4, Offutt Air Force Base, Nebraska
(Pre-Draft Report, August 1998).
Zheng, Chunmiao, 1990. A modular Three-Dimensional Transport Model for Simulation of Advection,
Dispersion, and Chemical Reactions of Contaminants in Groundwater Systems. S.S. Papadopulos and
Associates, Inc.
81 H:\Dynamac\RobG_Reporf\Rev_2\vol1.WPD
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FIGURES
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H012009A.DWG
-N-
LEGEND
PROPERTY BOUNDARY
2400
ADAPTED FROM DAMES & MOORE (1997)
Figure 4—1. Site location map, Kentucky.
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H012010A.DWG
BW-1931
BW-1932
BW-1933
BW-1934
BW-1948
BW-1935
1949
BW-1928
BW-1929
BW-1930
BW-1936
BW-1937
BW-1938
BW-1939
BW-1940
SCALE IN FEET
NOTE: REMEDIATION WELLS ARE ILLUSTRATED ON THIS FIGURE. ALL WATER LEVEL DATA POINTS NOT SHOWN.
Figure 4—2. Groundwater elevation contours, Kentucky.
WATER LEVEL
ELEVATION (FT MSL)
PROPERTY BOUNDARY
BW (ORIGINAL DESIGN)
BW (SUBSEQUENT TO
ORIGINAL DESIGN)
SW
OW
ADAPTED FROM DAMES & MOORE (1997),
JULY 1997 CONDITIONS
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H01201 1A.DWG
BW-1931
BW-1932
BW-1933
BW-1934
BW-1948
BW-1935
BW-1928
BW-1929
BW-193Q
OW-1923
BW-1936
BW-1937
BW-1938
BW-1939
BW-1940
'I BW-1953
BW-1944
SW-192
SW-192
SCALE \\\ FEET
Figure 4-3. EDC concentrations and current remediation wells, Kentucky.
EDC CONCENTRATION
CONTOUR (ug/L)
PROPERTY BOUNDARY
BW (ORIGINAL DESIGN)
BW (SUBSEQUENT TO
ORIGINAL DESIGN)
SW
OW
CONG. CONTOURS PREPARED BY DAMES
& MOORE, SEPTEMBER 1996 CONDITIONS
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H012012A.DWG
BW-1938
BW-1939
BW-1940
BW-1950
BW-1947
BW-1952
SCALE IN FEET
BENZENE CONCENTRATION
CONTOUR (ug/L)
PROPERTY BOUNDARY
BW (ORIGINAL DESIGN)
BW (SUBSEQUENT TO
ORIGINAL DESIGN)
CONG. CONTOURS PREPARED BY DAMES
& MOORE, SEPTEMBER 1996 CONDITIONS
Figure 4-4. Benzene concentrations and current remediation wells, Kentucky.
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q
CM
o
o
CM
Enlarged Map Area
UTAH
GREAT SALT
LAKE
SALT LAKE CITY
~^—
80
138
M
GRANTSVILLEA N11
TOOELE ARMY
DEPOT (TEAD)
RUSH VALLEY
UTAH
LAKE
PROVO
SCALE IN MILES
ADAPTED FROM KLEINFELDER (1998)
Figure 5-1. Site location map, Tooele.
HSI
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ro
O
o
CM
INDUSTRIAL
WASTE
LAGOON
INDUSTRIAL
AREA
LEGEND
4480
DEEP TCE CONTOUR
SHALLOW TCE CONTOUR
(DASHED WHERE INFERRED)
BEDROCK BLOCK AS IMPLEMENTED
IN MODEL
GROUNDWATER ELEVATION CONTOUR
0 3000
SCALE IN FEET
6000
WATER LEVELS, MARCH 1997, TAKEN
FROM KLEINFELDER (1998)
Figure 5 — 2. Groundwater elevation contours,
Tooele.
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IN
1-10
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I-7
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D
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D
, I
INDUSTRIAL
WASTE
LAGOON
LEGEND
1-4 INJECTION WELL
E-4 EXTRACTION WELL
n EX. WELL IN LAYER 1
-$- EX. WELL IN LAYER 2
-*- EX. WELL IN LAYERS 1 & 2
+ EX. WELL IN LAYERS 1, 2 & 3
INDUSTRIAL
AREA
DEEP TCE CONTOUR (ug/L or ppb)
SHALLOW TCE CONTOUR (ug/L or ppb)
(DASHED WHERE INFERRED)
UNLINED DITCH
0
3000
6000
BEDROCK BLOCK AS
IMPLEMENTED IN MODEL
SCALE IN FEET
ADAPTED FROM KLEINFELDER (1998)
Figure 5 — 3. TCE concentrations and current
remediation wells, Tooele.
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0 10
20
SCALE IN MILES
ADAPTED FROM WOODWARD-CLYDE (1998)
Figure 6 — 1. Site location map, Offutt.
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LEGEND
WATER LEVEL
ELEVATION (FT MSL)
PROPERTY BOUNDARY
500
SCALE IN FEET
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-N-
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Figure 6-2. Groundwater elevation contours, Offutt.
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LEGEND
SHALLOW CORE ZONE:
TARGET VOCs > 1000 ug/L
SHALLOW-INTERMEDIATE CORE ZONE:
TARGET VOCs > 1000 ug/L
INTERMEDIATE CORE ZONE:
TARGET VOCs > 1000 ug/L
DEEP CORE ZONE:
TARGET VOCs > 1000 ug/L
SOUTHERN PLUME
PROPERTY BOUNDARY
SCALE IN EEET
ADAPTED FROM WOODWARD-CLYDE (1997)
\
Figure 6 — 3. Southern plume and current remediation
Offutt.
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TABLES
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Table 2-1. Format of the screening spreadsheet.
Screening Analysis
Site: Acme
Scenario: Sample
Discount Rate: 0.05
O&M Costs
-Electric
-Materials (pH adjustment)
-Maintenance
-Discharge Fees
-Annual O&M
-Analytical
-Steam
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Engineering Design
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Other 1
-Other 2
-Other 3
Total Costs
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$25,000
$0
$15,000
$0
$40,000
$25,000
$0
$0
$0
$0
$0
$105,000
Total of Annual
Annual Costs # Years Costs
$160,000 20 $2,093,651
$67,ooo 20 $876,716
$50,000 20 $654,266
$0 20 $0
$250,000 20 $3,271,330
$0 20 $0
$800,000 20 $10,468,257
$0 20 $0
$0 20 $0
$0 $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$1,327,000 $17,364,221
Total Costs
$2,093,651
$876,716
$654,266
$0
$3,271,330
$0
$10,468,257
$0
$0
$25,000
$0
$15,000
$0
$40,000
$25,000
$0
$0
$0
$0
$0
$17,469,221
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
None
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Screening Analysis
Table 4-1. Current system, Kentucky.
Site: Kentucky
Scenario: Current System
Discount Rate: 0.05
O&M Costs
-Electric
-Materials (pH adjustment)
-Maintenance
-Discharge Fees
-Annual O&M
-Analytical
-Steam
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Engineering Design
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Other 1
-Other 2
-Other 3
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
I oidi oi Mrinual
Annual Costs # Years Costs
$200,000 20 $2,617,064
$100,000 20 $1,308,532
$50,000 20 $654,266
$0 20 $0
$250,000 20 $3,271,330
$0 20 $0
$1,200,000 20 $15,702,385
$0 20 $0
$0 20 $0
$0 $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
Total Costs
$2,617,064
$1,308,532
$654,266
$0
$3,271,330
$0
$15,702,385
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
Total Costs || $0 1| $1,800,000 $23,553,578 1| $23,553,578
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
Analytical costs not included.
-------
Table 4-2. Scenario 1, Kentucky: cut pumping by 33 percent, no new wells.
Screening Analysis
Site: Kentucky
Scenario: 1) Cut rate by 33%, no new wells
Discount Rate: 0.05
O&M Costs
-Electric
-Materials (pH adjustment)
-Maintenance
-Discharge Fees
-Annual O&M
-Analytical
-Steam
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Engineering Design
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Other 1
-Other 2
-Other 3
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$25,000
$0
$15,000
$0
$40,000
$25,000
$0
$0
$0
$0
$0
Total of Annual
Annual Costs # Years Costs
$160,000 20 $2,093,651
$67,ooo 20 $876,716
$50,000 20 $654,266
$0 20 $0
$250,000 20 $3,271,330
$0 20 $0
$800,000 20 $10,468,257
$0 20 $0
$0 20 $0
$0 $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
Total Costs
$2,093,651
$876,716
$654,266
$0
$3,271,330
$0
$10,468,257
$0
$0
$25,000
$0
$15,000
$0
$40,000
$25,000
$0
$0
$0
$0
$0
Total Costs || $105,000 || $1,327,000 $17,364,221 || $17,469,221
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
Assume pumping rate cut by approximately 33%
Assume steam cut 33%, materials cut by 33%
Assume electric cut 20%
Assume no new wells
-------
Table 4-3. Scenario 2, Kentucky: cut pumping by 33 percent, five new wells.
Screening Analysis
Site: Kentucky
Scenario: 2) Cut rate by 33%, 5 new wells
Discount Rate: 0.05
O&M Costs
-Electric
-Materials (pH adjustment)
-Maintenance
-Discharge Fees
-Annual O&M
-Analytical
-Steam
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Engineering Design
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Other 1
-Other 2
-Other 3
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$25,000
$0
$15,000
$0
$40,000
$25,000
$100,000
$0
$0
$0
$0
Total of Annual
Annual Costs # Years Costs
$160,000 20 $2,093,651
$67,ooo 20 $876,716
$50,000 20 $654,266
$0 20 $0
$250,000 20 $3,271,330
$0 20 $0
$800,000 20 $10,468,257
$0 20 $0
$0 20 $0
$0 $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
Total Costs
$2,093,651
$876,716
$654,266
$0
$3,271,330
$0
$10,468,257
$0
$0
$25,000
$0
$15,000
$0
$40,000
$25,000
$100,000
$0
$0
$0
$0
Total Costs || $205,000 || $1,327,000 $17,364,221 || $17,569,221
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
Assume pumping rate cut by approximately 33%
Assume steam cut 33%, materials cut by 33%
Assume electric cut 20%
Assume 5 new wells @ $20K/well
-------
Screening Analysis
Table 5-1. Current system, Tooele.
Site: Tooele
Scenario: Current System
Discount Rate: 0.05
O&M Costs
-Electric
-Materials (Sodium Metaphosphate)
-Maintenance
-Discharge Fees
-Annual O&M
-Analytical
-Other 1
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Engineering Design
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Other 1
-Other 2
-Other 3
Total Costs
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
Total of Annual
Annual Costs # Years Costs
$1,000,000 20 $13,085,321
$200,000 20 $2,617,064
$30,000 20 $392,560
$0 20 $0
$500,000 20 $6,542,660
$80,000 20 $1 ,046,826
$0 20 $0
$0 20 $0
$0 20 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$1,810,000 $23,684,431
Total Costs
$13,085,321
$2,617,064
$392,560
$0
$6,542,660
$1 ,046,826
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$23,684,431
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
None
-------
Table 5-2. Scenario 1, Tooele: cut pumping by 33 percent, no new wells.
Screening Analysis
Site: Tooele
Scenario: 1) Cut rate by 33%, no new wells
Discount Rate: 0.05
O&M Costs
-Electric
-Materials (Sodium Metaphosphate)
-Maintenance
-Discharge Fees
-Annual O&M
-Analytical
-Other 1
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Engineering Design
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Other 1
-Other 2
-Other 3
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$10,000
$30,000
$25,000
$0
$40,000
$40,000
$0
$0
$0
$0
$0
Total of Annual
Annual Costs # Years Costs
$800,000 20 $10,468,257
$133,333 20 $1,744,705
$30,000 20 $392,560
$0 20 $0
$500,000 20 $6,542,660
$80,ooo 20 $1,046,826
$0 20 $0
$0 20 $0
$0 20 $0
$0 $0
$0 $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
Total Costs
$10,468,257
$1,744,705
$392,560
$0
$6,542,660
$1,046,826
$0
$0
$0
$10,000
$30,000
$25,000
$0
$40,000
$40,000
$0
$0
$0
$0
$0
Total Costs || $145,000|| $1,543,333 $20,195,007|| $20,340,007
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
Assume pumping rate cut from 7500 gpm to 5000 gpm (33%)
Assume electric cut 20%
Assume materials cut 33%
-------
Table 5-3. Scenario 2, Tooele: cut pumping by 33 percent, five new wells.
Screening Analysis
Site: Tooele
Scenario: 2) Cut rate by 33%, 5 new wells
Discount Rate: 0.05
O&M Costs
-Electric
-Materials (Sodium Metaphosphate)
-Maintenance
-Discharge Fees
-Annual O&M
-Analytical
-Other 1
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Engineering Design
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Other 1
-Other 2
-Other 3
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$10,000
$30,000
$25,000
$0
$40,000
$40,000
$1,500,000
$0
$0
$0
$0
Total of Annual
Annual Costs # Years Costs
$800,000 20 $10,468,257
$133,333 20 $1,744,705
$30,000 20 $392,560
$0 20 $0
$500,000 20 $6,542,660
$80,ooo 20 $1,046,826
$0 20 $0
$0 20 $0
$0 20 $0
$0 $0
$0 $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
$o $0
Total Costs
$10,468,257
$1,744,705
$392,560
$0
$6,542,660
$1,046,826
$0
$0
$0
$10,000
$30,000
$25,000
$0
$40,000
$40,000
$1,500,000
$0
$0
$0
$0
Total Costs || $1,645,000|| $1,543,333 $20,195,007 || $21,840,007
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
Assume pumping rate cut from 7500 gpm to 5000 gpm (33%)
Assume electric cut 20%
Assume materials cut 33%
Assume 5 new wells at $300K/well
-------
Table 6-1. Current system, Offutt: one new core well, 100 gpm at LF wells.
Screening Analysis
Site: Offutt
Scenario: Current System (Add 1 new core zone well, pump 200 gpm from 4 wells)
Discount Rate: 0.05
O&M Costs
-Electric
-Materials
-Maintenance (Labor)
-Discharge (Core & LF 150 gpm, 20 yrs)
-Annual O&M
-Analytical
-Discharge (Toe Well, 50 gpm, 10 yrs)
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Fixed Construction/All Scenarios
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Other 1
-Other 2
-Other 3
Total Costs
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$47,000
$0
$40,000
$0
$0
$0
$0
$87,000
Total of Annual
Annual Costs # Years Costs
$2,000 20 $26,171
$0 20 $0
$12,000 20 $157,024
$60,000 20 $785,119
$3,000 20 $39,256
$25,000 20 $327,133
$20,000 10 $162,156
$0 20 $0
$0 20 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$122,000 $1,496,859
Total Costs
$26,171
$0
$157,024
$785,119
$39,256
$327,133
$162,156
$0
$0
$0
$0
$0
$0
$47,000
$0
$40,000
$0
$0
$0
$0
$1,583,859
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
Toe well can be shut off in 10 yrs
-------
Table 6-2. Scenario 1, Offutt: reduce toe well pumping by 33 percent, no additional toe wells.
Screening Analysis
Site: Offutt
Scenario: 1) Reduce pumping at toe by 33%, no additional toe wells
Discount Rate: 0.05
O&M Costs
-Electric
-Materials
-Maintenance (labor)
-Discharge (Core & LF 150 gpm, 20 yrs)
-Annual O&M
-Analytical
-Discharge (Toe Well, 33 gpm, 10 yrs)
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Fixed Construction/All Scenarios
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Other 1
-Other 2
-Other 3
Total Costs
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$15,000
$15,000
$0
$47,000
$20,000
$40,000
$0
$0
$0
$0
$137,000
Total of Annual
Annual Costs # Years Costs
$2,000 20 $26,171
$0 20 $0
$12,000 20 $157,024
$60,000 20 $785,119
$3,000 20 $39,256
$25,000 20 $327,133
$13,333 10 $108,102
$0 20 $0
$0 20 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$115,333 $1,442,804
Total Costs
$26,171
$0
$157,024
$785,119
$39,256
$327,133
$108,102
$0
$0
$0
$15,000
$15,000
$0
$47,000
$20,000
$40,000
$0
$0
$0
$0
$1,579,804
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
Assume LF pumping (100 gpm) and core pumping (50 gpm) is fixed
Assume toe pumping (50 gpm) can be cut by 33%
-------
Table 6-3. Scenario 2, Offutt: reduce toe well pumping by 33 percent, two additional toe wells.
Screening Analysis
Site: Offutt
Scenario: 2) Reduce pumping at toe by 33%, 2 new toe wells
Discount Rate: 0.05
O&M Costs
-Electric
-Materials
-Maintenance (labor)
-Discharge (Core & LF 150 gpm, 20 yrs)
-Annual O&M
-Analytical
-Discharge (Toe Well, 33 gpm, 10 yrs)
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Fixed Construction/All Scenarios
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Two New Wells Near Toe
-Other 2
-Other 3
Total Costs
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$15,000
$15,000
$0
$47,000
$20,000
$40,000
$0
$80,000
$0
$0
$217,000
Total of Annual
Annual Costs # Years Costs
$2,000 20 $26,171
$0 20 $0
$12,000 20 $157,024
$60,000 20 $785,119
$3,000 20 $39,256
$25,000 20 $327,133
$13,333 10 $108,102
$0 20 $0
$0 20 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$115,333 $1,442,804
Total Costs
$26,171
$0
$157,024
$785,119
$39,256
$327,133
$108,102
$0
$0
$0
$15,000
$15,000
$0
$47,000
$20,000
$40,000
$0
$80,000
$0
$0
$1,659,804
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
Assume LF pumping (100 gpm) and core pumping (50 gpm) is fixed
Assume toe pumping (50 gpm) can be cut by 33%
-------
Table 6-4. Scenario 3, Offutt: do not install new core well.
Screening Analysis
Site: Offutt
Scenario: 3) Don't install core well, increase toe well pumping
Discount Rate: 0.05
O&M Costs
-Electric
-Materials
-Maintenance (labor)
-Discharge (LF 100 gpm, 20 yrs)
-Annual O&M
-Analytical
-Discharge (Toe Well, 75 gpm, 20 yrs)
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Fixed Construction/All Scenarios
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Other 1
-Other 2
-Other 3
Total Costs
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$15,000
$15,000
$0
$47,000
$20,000
$0
$0
$0
$0
$0
$97,000
Total of Annual
Annual Costs # Years Costs
$2,000 20 $26,171
$0 20 $0
$12,000 20 $157,024
$40,000 20 $523,413
$3,000 20 $39,256
$25,000 20 $327,133
$30,000 20 $392,560
$0 20 $0
$0 20 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$112,000 $1,465,556
Total Costs
$26,171
$0
$157,024
$523,413
$39,256
$327,133
$392,560
$0
$0
$0
$15,000
$15,000
$0
$47,000
$20,000
$0
$0
$0
$0
$0
$1,562,556
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
Assume LF pumping (100 gpm) and no core pumping
Assume toe pumping of 75 gpm for containment, required for 20 yrs
-------
Table 6-5. Scenario 4, Offutt: do not install new core well, two additional toe wells.
Screening Analysis
Site: Offutt
Scenario: 4) Don't install core well, increase toe well pumping, 2 new Toe wells
Discount Rate: 0.05
O&M Costs
-Electric
-Materials
-Maintenance (labor)
-Discharge (LF 100 gpm, 20 yrs)
-Annual O&M
-Analytical
-Discharge (Toe Well, 75 gpm, 20 yrs)
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Fixed Construction/All Scenarios
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Two New Wells Near Toe
-Other 2
-Other 3
Total Costs
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$15,000
$15,000
$0
$47,000
$20,000
$0
$0
$80,000
$0
$0
$177,000
Total of Annual
Annual Costs # Years Costs
$2,000 20 $26,171
$0 20 $0
$12,000 20 $157,024
$40,000 20 $523,413
$3,000 20 $39,256
$25,000 20 $327,133
$30,000 20 $392,560
$0 20 $0
$0 20 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$112,000 $1,465,556
Total Costs
$26,171
$0
$157,024
$523,413
$39,256
$327,133
$392,560
$0
$0
$0
$15,000
$15,000
$0
$47,000
$20,000
$0
$0
$80,000
$0
$0
$1,642,556
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
Assume LF pumping (100 gpm) and no core pumping
Assume toe pumping of 75 gpm for containment, required for 20 yrs
-------
Table 6-6. Scenario 5, Offutt: pumping at LF wells reduced fifty percent.
Screening Analysis
Site: Offutt
Scenario: 5) Cut pumping at LF wells in half
Discount Rate: 0.05
O&M Costs
-Electric
-Materials
-Maintenance (Labor)
-Discharge (Core & LF 100 gpm, 20 yrs)
-Annual O&M
-Analytical
-Discharge (Toe Well, 50 gpm, 10 yrs)
-Other 2
-Other 3
Costs of Analysis
-Flow Modeling
-Transport Modeling
-Optimization
-Other 1
System Modification Costs
-Fixed Construction/All Scenarios
-Regulatory Process
-New wells/pipes/equipment
-Increased Monitoring
-Other 1
-Other 2
-Other 3
Total Costs
Up-Front Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
$0
$15,000
$0
$0
$47,000
$20,000
$40,000
$0
$0
$0
$0
$122,000
Total of Annual
Annual Costs # Years Costs
$2,000 20 $26,171
$0 20 $0
$12,000 20 $157,024
$40,000 20 $523,413
$3,000 20 $39,256
$25,000 20 $327,133
$20,000 10 $162,156
$0 20 $0
$0 20 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$0 $0
$102,000 $1,235,153
Total Costs
$26,171
$0
$157,024
$523,413
$39,256
$327,133
$162,156
$0
$0
$0
$15,000
$0
$0
$47,000
$20,000
$40,000
$0
$0
$0
$0
$1,357,153
Note: All costs are in present-day dollars. The discount rate is applied to annual costs to calculate the Net Present Value (NPV).
The PV function in Microsoft Excel was utilized to calculate NPV, with payments applied at the beginning of each year.
Assumptions
Reduce LF wells from 100 to 50 gpm
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APPENDIX A:
SAMPLE CALCULATIONS USING DIFFERENT
VALUES FOR DISCOUNT RATE
The discount rate accounts for the fact that future money is generally worth less than present-day money.
The basis of the discount rate is that money, if not spent today, can typically be invested at a rate that
exceeds inflation.
If the discount rate is 0 percent, spending $1M today has the same cost as spending $100K/yr (indexed to
present-day dollars) for 10 yrs. However, if the discount rate is greater than 0 percent, spending $1M
today is more costly than spending $100K/yr (indexed to present-day dollars) for 10 yrs. The reason is
that the funds not spent each year are assumed to be invested at a rate exceeding inflation (by an amount
equal to the discount rate).
In the case studies presented in the main report, a discount rate of 5 percent was utilized. Discount rate is
a parameter that must be estimated for future years, and therefore is subject to uncertainty. In some cases
a discount rate of 0 percent may be appropriate (e.g., money not spent today is not open for investment at
rates exceeding inflation).
To illustrate the impact of the discount rate on cost calculations, the screening results for the Tooele Case
Study (Section 5 of the Report) are compared to results generated with different values for discount rate
(Table A-l). The comparison illustrates that the total dollar estimate for each scenario is higher when the
discount rate is lower, because future dollars are not discounted as much. For the same reason, net
savings indicated for Scenario 1 and Scenario 2 (relative to the baseline scenario) are greater when the
discount rate is lower (again, savings each year are not discounted as much when discount rate is lower).
(See Table A-l on Next Page)
A I H:\Dynamac\RobG_Report\Rev_2\vol1.WPD
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Table A-l. Tooele screening calculations for different values of discount rate.
Discount Rate = 0.0%
Baseline Scenario
Scenario #1
Scenario #2
Up-Front Costs
($)
$0
$145,000
$1,645,000
Annual Costs
($/yr)
$1,810,000
$1,543,333
$1,543,333
Sum of Annual
Costs, 20 yrs
($NPV)
$36,200,000
$30,866,660
$30,866,660
Total Cost
($NPV)
$36,200,000
$31,011,660
$32,511,660
Discount Rate = 2.5%
Baseline Scenario
Scenario #1
Scenario #2
Up-Front Costs
($)
$0
$145,000
$1,645,000
Annual Costs
($/yr)
$1,810,000
$1,543,333
$1,543,333
Sum of Annual
Costs, 20 yrs
($NPV)
$28,921,793
$24,660,750
$24,660,750
Total Cost
($NPV)
$28,921,793
$24,805,750
$26,305,750
Discount Rate = 5.0%
Baseline Scenario
Scenario #1
Scenario #2
Up-Front Costs
($)
$0
$145,000
$1,645,000
Annual Costs
($/yr)
$1,810,000
$1,543,333
$1,543,333
Sum of Annual
Costs, 20 yrs
($NPV)
$23,684,431
$20,195,007
$20,195,007
Total Cost
($NPV)
$23,684,431
$20,340,007
$21,840,007
Discount Rate = 7.5%
Baseline Scenario
Scenario #1
Scenario #2
Up-Front Costs
($)
$0
$145,000
$1,645,000
Annual Costs
($/yr)
$1,810,000
$1,543,333
$1,543,333
Sum of Annual
Costs, 20 yrs
($NPV)
$19,835,932
$16,913,507
$16,913,507
Total Cost
($NPV)
$19,835,932
$17,058,507
$18,558.507
A-2
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