n, EPA
United States
Environmental Protection
Agency
Off ice of
Solid Waste and
Emergency Response
Publication No.
9375.5-06/FS
April 1990
The Cost of
Remedial Action Model
Office of Emergency and Remedial Response
Hazardous Site Control Division (OS-220)
Quick Reference Fact Sheet
USER
A
<7
CORA
MODEL
INTRODUCTION
The Cost of Remedial Action (CORA) model is a computerized expert advisor used to select
remedial actions for Superfund hazardous waste sites and estimate their costs. It may also beused
for RCRA corrective actions. The model is used for both current site-specific estimates, and for
program budgeting and planning.
The expert system, with its technical information and regulatory interpretations, interacts with
the user to guide in the selection of a remedy and to recommend a range of remedial action
technologies at a specific site. The cost system is used to develop cost estimates for the remedial
action scenario. The system provides order-of-magnitude estimates for both capital and annual
O&M costs. Theusermustmanuallyextrapolatethesecoststodetermine total present and future
worth. The model is not currently designed to develop multiyear groundwater treatment
scenarios. Both the expert system and the cost system have been validated, and the model has
gained widespread use since its first release in 1987. ThenewestreleasewillbeavailableinMay
of 1990.
This short sheet describes the following aspects of the CORA model:
• Development
• Testing
Structure and function
• Applications.
Finally, the short sheet provides additional sources of information on the CORA model.
DEVELOPMENT OF THE CORA MODEL
The Superfund program requires accurate cost estimates to manage current activities and develop budgets. In order to improve
the accuracy and objectivity of cost estimates, EPA conducted a study in 1983 to quantitatively define pricing factors for
remedial actions. A modeling approach was selected to develop pricing factors because of limited historical construction cost
information. Information used to develop these earlycostmodels included data about conditions atasampleof Superfund sites,
categorizations of site types, and guidance criteria for selecting remedies. This information was aggregated to obtain budget
pricing factors.
In 1985, EPA attempted to dis-aggregate early modeling results to obtain site-specific estimates. The variability of these
estimates confirmed the need for different modeling tools to determine accurate site-specific costs. In addition, EPA needed
a method to estimate remedial action costs in the pre-feasibility stage of analysis. The CORA model was developed in response
to these needs, and is used to select remedial action;technejjGJues and estimate Superfund costs on a site-specific basis.
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TESTING OF THE CORA MODEL
In order to confirm the accuracy of the COR.A model, a validation exercise was performed by an independent consultant. The
methodology employed by the study included examining the technology being implemented at each site, loading this data into
the CORA model, and comparing CORA estimates with actual costs (either bid or construction). In May of 1987, the model
was used to examine cost estimates for 12 sites. The twelve sites were either in final design, had bids established, or were in
construction. Results of the analysis showed nine of the 12 were in the range of -30% to +50% of the CORA projections.
Modifications were made to the model and the results obtained in June of 1988 showed all 12 sites to be within range.
The consultant also conducted a subjective evaluation of the expert system of the model. This aspect of the validation exercise
sought to determine whether the CORA model recommendations conformed with good hazardous waste engineering practice,
and were reasonable solutions from an engineering perspective. Results showed the model to be successful in meeting both
criteria.
In a separate validation study conducted in 1990, the Department of Energy reviewed 25 RODs against the recommendations
generated by the CORA model on these 25 sites. Results of this comparison revealed that 97% of the CORA model
recommendations were in fact ROD alternatives.
STRUCTURE AND FUNCTION OF THE CORA MODEL
The CORA model includes two independent subsystems: an expert system and a cost system. The expert system uses site
information generaUy accessible at the remedial investigation stage to recommend a range of remedial response actions from
among 42 different technologies (see table). The cost system is used to develop estimates for the technologies selected, or may
be used to independently assess remedy recommendations from other sources. The following subsections describe the expert
system and the cost system more fully. -.
CORA SYSTEM COMPONENT DETAILS
Technology Cost Modules
Containment Treatment Disposal
Technologies: Technologies: Technologies:
Soil Cap Air Stripping Offsite RCRA Landfill
Asphalt Cap Vapor Phase Carbon Onsite RCRA Landfill
Multilayered RCRA Cap Activated Carbon Below Grade
Surface Controls Metals Precipitation Above Grade
Slurry Wall Activated Sludge Offsite Solid Waste Landfill
Soil Vapor Extraction Discharge to POTW
Removal Technologies: Soil Flushing Discharge to Surface Water
Home Carbon Units Water Reinjection
Drum Removal Offsite RCRA Treatment Water Infiltration
Soil Excavation Offsite RCRA Incineration
Sediment Dredging Onsite Incineration Miscellaneous
Pumping Contained Wastes Solidification Technologies:
GroundwaterExtraction InSitu Biodegredation
Active Landfill Gas Collection Ion Exchange Transportation
Pressure Filtration Municipal Water Supply
Flaring Groundwater Monitoring
Soil Slurry Bioreactor Access Restrictions
Insitu Stabilization Health and Safety
Site Preparation
Site Administration
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Expert System
Cost System
The expert system contains the data that enables
the CORA model to evaluate the information
provided by the user. The user defines the site
by responding to system-selected questions for
waste types within a contaminated area of the
site. The expert system analyzes the site based
on user responses by focusing on up to 13
different types of waste matrices ranging from
contaminated soils to bayous, to drums, to
buildings, and offers recommendations to
remedy the site. The CORA expert system’s
knowledge bases have approximately 670
decision rules to apply the 42 available
technologies. The decision rules incorporate
technology-specific engineering expertise,
statute interpretations, and policy issues. The
user can change responses to questions posed
by the system, but cannot alter the decision
rules. The system provides paper output of
questions and responses to questions for future
use. Thus, the system enables the user to
perfonn sensitivity analyses by exploring
alternative outcomes based on different site
information.
The CORA cost system is used to develop
order-of-magnitude cost estimates (-30% to
+50%) for sites after the response action
scenarios are developed, using the expert system
or other sources. The CORA cost system
organizes cost estimates by site, operable unit,
scenario, and technology. The system and the
user interact to complete this information for a
site previously entered into the data base or for
a new site. The CORA cost system calculates
capital and first-year operation and maintenance
(O&M) cost estimates for each technology
selected. The user may save outputs to the data
base for subsequent analysis. In addition, the
CORA model generates a total summary report
for a Site or operable unit for both capital and
O&M costs. The summary report includes costs
incurred by construction and operation of
individual unit processes and operations, costs
for items such as site preparation and
administration, startup, permitting and legal
services, permit and insurance renewal, services
during construction, and bid and scope
contingencies.
Hardware Requirements
The CORA model requires the following computer hardware
specifications:
• IBM compatible PC
• MS-DOS environment
• 640K RAM
• 3MBofharddiskspace.•
The CORA model is a stand-aloneapplication, not designed
for LAN use.
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PRESENT AND FUTURE APPUCATIONS OF THE CORA MODEL
The CORA model is a powerful tool that saves time and increases the user’s awareness of the scoping process, policy issues,
technology costs, and design factors when selecting remediation schemes. Users have reported that, in particular, the expert
system mcreases awareness of regulatory requirements and restrictions. The model also familiarizes them with basic design
elements and individual technology costs. The CORA model has been used for several purposes since it was developed, tested,
and approved. The CORA model was used to make cost estimates for 97 Superfund sites likely to be FY 1989 remedial action
candidates. Theresults of the CORA expertsystem and costsystem runs were combined with other information to developEPA’s
FY 1989 budget. The model has subsequently been used to develop costs for components of FY 1991 and 1992 budgets. CORA
model data has helped EPA shape the selection of remedies under SARA.
The CORA model was applied to Navy installation restoration program sites to estimate Defense Environmental Restoration Act
funding for FY 1989, 1990, and 1991. In addition, the Department of Defense uses the CORA model to develop remedial ac-
tion strategies and estimate their total rernediation costs.
APPL!C TIONS OF THE CORA MODEL
User: Purpose: - Benefits:
EPA • Develop Superfund remedialion budgets • Saves time -- 1-3
Perform initial site-specific remediation scoping hours to scope and
cost a remedial action
Other Federal ‘Estimate outyear and total programmatic scenario vs 20-60
Agencies remediation budgets hours without the
Private Jndustiy ‘Anticipate cost effects for Regulatory Impact model
Analyses of new environmental regulations i ens 5 users
awareness of
States Estimate site-specific remediation budgeting and scoping scoping, policies,
regulations, design
All of the ‘Screen, scope, and budget for technology of RCRA factors, and
Above Corrective Actions and closures technology costs
As the model is upgraded, new versions will become available. The newest version is due to be released in May 1990 and will
include several new technologies, new cost algorithms, and new market prices for offsite technologies.
TO OBTAIN THE CORA MODEL OR MORE INFORMATION
Federal and State agencies may obtain a limited number of copies of the CORA model from EPA at no cost. The general public
may obtain the CORA model from EPA for $280, the cost of reproduction and support. The CORA model package consists of
8 diskettes, a comprehensive user’s manual, and one hour of telephone information and assistance. The user’s manual contains
required information about remedial technologies, cost assumptions, design ranges, technology uses, and schematics for the
technologies. The following publications provide additional detail on the CORA model:
o “A Model for Estimating the Cost of Superfund Remedial Actions,” Richard K. Biggs and R. Benson Fergus, P.E.,
HMCRI proceedings of the 8th National Superfund Conference, Washington, D.C., November 16-18, 1987
o “The Cost of Remedial Actions Model: Practical Applications,” Richard K. Biggs and Jacqueline A. Crenca, September,
1988
o “The Cost of Remedial Actions (CORA) Model: Overview and Applications,” Richard K. Biggs, Kevin Klink, Jacqueline
Crenca, submitted for proceedings of HAZMACON 89, Santa Clara, Califorma, April 1989.
Information may be obtained through the following:
• The CORA Hotline - (703) 478-3566, to obtain the model and technical assistance, demonstrations, training
seminars, and CORA costing services
• The Superfund Docket and Information Center (SDIC) - (202) 382-6940, to obtain publications (including those
listed above) and directives
o The RCRA/Superfund Hotline - (202) 382-3000 or (800) 424-9346, for program information.
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