REMEDIATION SYSTEM EVALUATION
CLEBURN STREET WELL SUPERFUND SITE
GRAND ISLAND, NEBRASKA
Report of the Remediation System Evaluation,
Site Visit Conducted at the Cleburn Street Well Site
April 24, 2001
Final Report Submitted to Region 7
July 30, 2001
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NOTICE
Work described herein was performed by GeoTrans, Inc. (GeoTrans) and the United States Army Corps
of Engineers (USAGE) for the U.S. Environmental Protection Agency (U.S. EPA). Work conducted by
GeoTrans, including preparation of this report, was performed under Dynamac Contract No. 68-C-99-
256, Subcontract No. 91517. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
This document (EPA 542-R-02-008k) may be downloaded from EPA's Technology Innovation Office
website at www.epa.gov/tio or www.cluin.org/rse.
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EXECUTIVE SUMMARY
The Cleburn Street Well Superfund Site, encompasses 144 blocks of downtown Grand Island, Nebraska
and addresses contamination resulting from three dry cleaners and a solvents facility. The site consists of
five operable units (OUs):
OU1 is a soil vapor extraction (SVE) system that addresses the subsurface soil contamination
from the former One Hour Martinizing located on the corner of 4th and Eddy Streets;
OU2 is a pump-and-treat system that addresses the groundwater contamination associated with
the same facility;
OU3 and OU4 are monitored natural attenuation programs that address the groundwater
contamination associated with Liberty Cleaners and Ideal Cleaners, respectively; and
OU5 addresses the soil and groundwater contamination associated with the former Nebraska
Solvents.
This RSE report pertains to OU2, as it is the only Fund-lead pump-and-treat system within the site, and
also to OU1 as it relates to OU2. Both OU1 and OU2 began operation in 1998 to address contamination
associated with the One Hour Martinizing facility, and OU1 has since been turned over to the State as it is
considered a containment remedy. Tetrachlorethylene (PCE) is the primary contaminant of concern for
OU2 although other volatile organic compounds VOCs must be addressed as stipulated by the ROD.
High concentrations of PCE indicate the presence of freephase PCE in the form of a dense non-aqueous
phase liquid (DNAPL) that serves as a continuing source of dissolved phase PCE.
The pump-and-treat system consists of three extraction wells that pump a total of approximately 80 gpm
and an air stripper that removes PCE from the extracted water. Treated water from the air stripper is
discharged to the local sanitary sewer. The operator checks on the system weekly and also during the
quarterly sampling events. Project management accounts for approximately 58% of the operations and
maintenance costs, which is high compared to operations and maintenance costs for similar systems.
The following recommendations are suggested to improve effectiveness:
The extraction wells are operating below designed pumping rates, possibly due to biofouling.
These wells should be rehabilitated to increase the extraction rates to their designed levels as
these higher rates may be required for plume capture.
The capture zone should be more thoroughly investigated and possibly improved. Vertical
variations in the hydraulic conductivity and the PCE contamination may discount the capture zone
analyses done to date. One shallow and one deep monitoring well should be installed immediately
downgradient of the extraction system to determine if it is capturing PCE from the source area.
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The current sampling protocol involves disposing of well-purge water into the storm sewer. As
this purged water has high PCE concentrations, this practice should be discontinued. The purged
water could be fed through the air stripper to remove the PCE.
The easy accessibility to groundwater suggests that unregistered private wells could be used for
water supply of local residences. Public records and previous surveys of wells in the area should
be reviewed for completeness to ensure no wells are operating in the vicinity of the site.
The high concentrations of PCE in groundwater and soil could result in harmful levels of PCE in
indoor air or standing water near the source area. Samples of air in nearby businesses and
standing water in the underground traffic-light vault should be analyzed for PCE.
Finally, the Pine Street well may still be used for water supply during periods of high demand. If
this is the case, that well should be sampled for PCE and site-related contaminants as it lies
approximately 1,500 feet downgradient of the source area.
Implementation of these recommendations would require approximately $21,000 in capital costs and an
approximate increase of $7,500 in annual operations and maintenance costs.
The following recommendations are suggested to reduce operating costs:
Because OU1 is managed by the State and OU2 is managed by the EPA, different contracts are
in place for operation of the two systems. However, the proximity of the two systems and the
use of a common contractor suggests that operation of the two systems could be accomplished
under a single contract. This could potentially reduce operator labor costs by $18,000 per year.
If a single contract is infeasible under current program guidelines, the separate contracts should
be coordinated such that operation and maintenance costs reflect a single site visit to address both
operable units.
The blower used for the OU1 SVE system is larger than necessary and is therefore operating
with the air intake valve opened. This blower could be replaced by a smaller, more efficient one
for $15,000. Savings of approximately $12,000 per year would result.
The life-cycle cost savings associated with these recommendations could offset those costs incurred from
implementing the recommendations to improve effectiveness.
In addition, to the above-mentioned recommendations and a number regarding technical improvement of
the SVE and pump-and-treat systems, this RSE report also suggests investigation and possibly
implementation of an air sparging system to address the freephase PCE in the form of dense non-aqueous
phase liquid (DNAPL). Such a system would likely significantly decrease the operating lifetime of the
two systems. Furthermore, an exit strategy based on precedents set by other operable units should be
developed to ensure the system does not operate longer than necessary.
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PREFACE
This report was prepared as part of a project conducted by the United States Environmental Protection
Agency (USEPA) Technology Innovation Office (TIO) and Office of Emergency and Remedial
Response (OERR). The objective of this project is to conduct Remediation System Evaluations
(RSEs) of pump-and-treat systems at Superfund sites that are "Fund-lead" (i.e., financed by USEPA).
RSEs are to be conducted for up to two systems in each EPA Region with the exception of Regions 4
and 5, which already had similar evaluations in a pilot project.
The following organizations are implementing this project.
Organization
Key Contact
Contact Information
USEPA Technology Innovation
Office
(USEPA TIO)
Kathy Yager
2890 Woodbridge Ave. Bldg. 18
Edison, NJ 08837
(732) 321-6738
Fax: (732) 321-4484
yager.kathleen@epa.gov
USEPA Office of Emergency and
Remedial Response
(OERR)
Paul Nadeau
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Mail Code 5201G
phone: 703-603-8794
fax: 703-603-9112
nadeau. paul@epa. gov
GeoTrans, Inc.
(Contractor to USEPA TIO)
Rob Greenwald
GeoTrans, Inc.
2 Paragon Way
Freehold, NJ 07728
(732) 409-0344
Fax: (732) 409-3020
rgreenwald@geotransinc. com
Army Corp of Engineers:
Hazardous, Toxic, and Radioactive
Waste Center of Expertise
(USAGE HTRW CX)
Dave Becker
12565 W. Center Road
Omaha, NE 68144-3869
(402) 697-2655
Fax: (402) 691-2673
dave.j. becker@nwd02. usace. army. mil
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The project team is grateful for the help provided by the following EPA Project Liaisons.
Region 1
Region 2
Region 3
Region 4
Region 5
Darryl Luce and Larry Brill
Diana Curt
Kathy Davies
Kay Wischkaemper
Dion Novak
Region 6
Region 7
Region 8
Region 9
Region 10
Vincent Malott
Mary Peterson
Armando Saenz
Herb Levine
Bernie Zavala
and Richard Muza
They were vital in selecting the Fund-lead pump-and-treat systems to be evaluated and facilitating
communication between the project team and the Remedial Project Managers (RPM's).
IV
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TABLE OF CONTENTS
EXECUTIVE SUMMARY i
PREFACE iii
TABLE OF CONTENTS v
1.0 INTRODUCTION 1
1.1 PURPOSE 1
1.2 TEAM COMPOSITION 1
1.3 DOCUMENTS REVIEWED 2
1.4 PERSONS CONTACTED 3
1.5 SITE LOCATION, HISTORY, AND CHARACTERISTICS 3
1.5.1 LOCATION 3
1.5.2 POTENTIAL SOURCES 4
1.5.3 HYDROGEOLOGIC SETTING 4
1.5.4 DESCRIPTION OF GROUND WATER PLUME 5
2.0 SYSTEM DESCRIPTION 6
2.1 SYSTEM OVERVIEW 6
2.2 EXTRACTION SYSTEM 6
2.2.1 OU1 EXTRACTION SYSTEM 6
2.2.2 OU2 EXTRACTION SYSTEM 6
2.3 TREATMENT SYSTEM 6
2.3.1 OU1 TREATMENT SYSTEM 6
2.3.2 OU2 TREATMENT SYSTEM 6
2.4 MONITORING SYSTEM 7
3.0 SYSTEM OBJECTIVES, PERFORMANCE AND CLOSURE CRITERIA 8
3.1 CURRENT SYSTEM OBJECTIVES AND CLOSURE CRITERIA 8
3.2 TREATMENT PLANT OPERATION GOALS 8
3.3 ACTION LEVELS 8
4.0 FINDINGS AND OBSERVATIONS FROM THE RSE SITE VISIT 9
4.1 FINDINGS 9
4.2 SUBSURFACE PERFORMANCE AND RESPONSE 9
4.2.1 WATER LEVELS AND CAPTURE ZONES 9
4.2.2 CONTAMINANT LEVELS 9
4.3 COMPONENT PERFORMANCE 10
4.3.1 EXTRACTION-WELL PUMPS AND PIPING 10
4.3.2 AIR STRIPPER 10
4.3.3 ACID WASH SYSTEM 10
4.3.4 SVEBLOWER 11
4.3.5 LIQUID AND VAPOR PHASE CARBON UNITS 11
4.4 COMPONENTS OR PROCESSES THAT ACCOUNT FOR MAJORITY OF COSTS 11
4.4.1 LABOR 11
4.4.2 CHEMICAL ANALYSIS (ON AND OFF SITE) 11
4.4.3 NON-UTILITY CONSUMABLES AND DISPOSAL COSTS 11
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4.4.4 UTILITY COSTS 11
4.5 RECURRING PROBLEMS OR ISSUES 12
4.6 REGULATORY COMPLIANCE 12
4.7 TREATMENT PROCESS EXCURSIONS AND UPSETS, ACCIDENTAL CONTAMINANT/REAGENT RELEASES . 12
4.8 SAFETY RECORD 12
5.0 EFFECTIVENESS OF THE SYSTEM TO PROTECT HUMAN HEALTH AND THE ENVIRONMENT 13
5.1 GROUND WATER 13
5.2 SURFACE WATER 13
5.3 AIR 13
5.4 SOILS 14
5.5 WETLANDS 14
6.0 RECOMMENDATIONS 15
6.1 RECOMMENDATIONS TO ENSURE EFFECTIVENESS 15
6.1.1 IMPROVE WELL-MAINTENANCE PROGRAM 15
6.1.2 DETERMINE CAPTURE-ZONE EFFECTIVENESS 15
6.1.3 MODIFY WELL-SAMPLING PROTOCOL 16
6.1.4 REVIEW PREVIOUS SURVEYS OF PRIVATE WELLS IN AREA 16
6.1.5 CONDUCT SAMPLING OF INDOOR AIR AND STANDING WATER 17
6.1.6 SAMPLE PINE STREET WELL FOR PCE 17
6.2 RECOMMENDATIONS TO REDUCE COSTS 17
6.2.1 COMBINE OPERATION OF OU1 AND OU2 AND REDUCE FREQUENCY OF PID MEASUREMENTS . 17
6.2.2 REPLACE SVE BLOWER WITH A SMALLER, MORE EFFICIENT UNIT 17
6.2.3 CONSIDER REDUCTIONS IN PROJECT MANAGEMENT COSTS 18
6.3 TECHNICAL IMPROVEMENT 18
6.3.1 MEASURE SVE WELL PARAMETERS 18
6.3.2 TREAT SVE CONDENSATE WITH AIR STRIPPER RATHER THAN CARBON 18
6.3.3 REFORMAT QUARTERLY PERFORMANCE REPORTS 18
6.3.4 DRAIN WATER FROM EXTRACTION-WELL VAULTS 19
6.3.5 SAMPLE MONITORING WELLS FOR ADDITIONAL PARAMETERS 19
6.4. RECOMMENDATIONS TO GAIN SITE CLOSEOUT 19
6.4.1 INVESTIGATE USE OF AIR SPARGING 19
6.4.2 DEVELOP AN EXIT STRATEGY 20
6.5 UNUSED GOVERNMENT-OWNED EQUIPMENT 20
7.0 SUMMARY 21
List of Tables
Table 2-1. Monitoring locations
Table 7-1. Cost summary table of individual recommendations
Table 7-2. Cost estimates for systems with and without implemented recommendations
List of Figures
Figure 1-1. Site layout showing the contaminant sources, groundwater extraction wells, SVE wells, and the 1999
PCE plume
VI
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1.0 INTRODUCTION
1.1 PURPOSE
In the OSWER Directive No. 9200.0-33, Transmittal of Final FYOO - FY01 Superfund Reforms
Strategy, dated July 7,2000, the Office of Solid Waste and Emergency Response outlined a
commitment to optimize Fund-lead pump-and-treat systems. To fulfill this commitment, the US
Environmental Protection Agency (USEPA) Technology Innovation Office (TIO) and Office of
Emergency and Remedial Response (OERR), through a nationwide project, is assisting the ten EPA
Regions in evaluating their Fund-lead operating pump-and-treat systems. This nationwide project is a
continuation of a demonstration project in which the Fund-lead pump-and-treat systems in Regions 4 and 5
were screened and two sites from each of the two Regions were evaluated. It is also part of a larger
effort by TIO to provide USEPA Regions with various means for optimization, including screening tools
for identifying sites likely to benefit from optimization and computer modeling optimization tools for pump
and treat systems.
This nationwide project identifies all Fund-lead pump-and-treat systems in EPA Regions 1 through 3 and 6
through 10, collects and reports baseline cost and performance data, and evaluates up to two sites per
Region. The site evaluations are conducted by EPA-TIO contractors, GeoTrans, Inc. and the United
States Army Corps of Engineers (USAGE), using a process called a Remediation System Evaluation
(RSE), which was developed by USAGE. The RSE process is meant to evaluate performance and
effectiveness (as required under the NCP, i.e., and "five-year" reviews), identify cost savings through
changes in operation and technology, assure clear and realistic remediation goals and exit strategy, and
verify adequate maintenance of Government-owned equipment.
The Cleburn Street Well Site was chosen because it is the only Fund-lead P&T system operating in
Region 7 at the time of this project. This report provides a brief background on the site and current
operations, a summary of the observations made during a site visit, and recommendations for changes and
additional studies. The cost impacts of the recommendations are also discussed.
A report on the overall results from the RSEs conducted at the Cleburn Street Well Site and other Fund-
lead pump-and-treat systems throughout the nation will also be prepared and will identify lessons learned
and typical costs savings.
1.2 TEAM COMPOSITION
The team conducting the RSE consisted of the following individuals:
Ed Mead, Chemical Engineer, USAGE HTRW CX
Dave Becker, Hydrogeologist, USAGE, HTRW CX
Peter Rich, Civil and Environmental Engineer, GeoTrans, Inc.
Doug Sutton, Water Resources Engineer, GeoTrans, Inc.
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1.3
DOCUMENTS REVIEWED
Author
Sverdrup Corporation
Sverdrup Corporation
US EPA
U.S. Department of
Health and Human
Services, Agency for
Toxic Substances and
Disease Registry
Sverdrup Environmental,
Inc.
Sverdrup Environmental,
Inc.
Sverdrup Environmental,
Inc.
Remediation
Technologies
Sverdrup Environmental,
Inc.
Sverdrup Environmental,
Inc.
Sverdrup Environmental,
Inc.
Black and Veatch
Date
5/1993
12/1993
6/7/1996
3/26/1997
9/22/1997
9/22/1997
9/22/1997
6/10/1998
7/1999
7/1999
9/29/1999
10/20/2000
Title/Description
Remedial Investigation Report for the Remedial
Investigation/Feasibility Study at the Cleburn Street Well
Site, Grand Island, Nebraska, Vol. I
Remedial Investigation Study for the Remedial
Investigation/Feasibility Study at the Cleburn Street Well
Site, Grand Island, Nebraska, Phase III Addendum
Record of Decision, Cleburn Street Well Superfund Site,
Grand Island, Nebraska
Public Health Assessment, Cleburn Street Well Superfund
Site, Grand Island, Hall County, Nebraska
Final Remedial Design, Cleburn Street Site, Operable Unit
No. 1 & 2, Grand Island, Nebraska, Vol. I, Design Report
Final Remedial Design, Cleburn Street Site, Operable Unit
No. 1 & 2, Grand Island, Nebraska, Vol. 2, Design
Specifications
Final Remedial Design, Cleburn Street Site, Operable Unit
No. 1 & 2, Grand Island, Nebraska, Vol. 3, Design
Drawings
Site Characterization Summary Report, Remedial
Investigation, Former Nebraska Solvents Site - OU5,
Cleburn Street Well Superfund Site, Grand Island,
Nebraska
Operation and Maintenance Plan, Cleburn Street Site,
Operable Unit No. 1 & 2, Grand Island, Nebraska
Operation and Maintenance Manual, Air Stripper System,
Cleburn Street Site, Operable Units No. 1 & 2, Grand
Island, Nebraska
Second Semi-annual Performance Report, Cleburn Street
Site, Operable Units 1 and 2
Annual Performance Report, Cleburn Street Site,
Operable Unit 2
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Author
Black and Veatch
Christopher Exstrom
Christopher Exstrom
Black and Veatch
Date
12/12/2000
2001
2001
3/9/2001
Title/Description
October 2000 Quarterly Performance Report, Cleburn
Street Site, Operable Unit 2
2000 Annual Report on Volatile Organic Compound Level
Monitoring at the Groundwater Monitoring Wells,
Operating Units No. 3 and 4, Cleburn Street Superfund
Site, Grand Island, Nebraska
2000 Annual Report on Volatile Organic Compound Level
Monitoring at the Soil-Vapor Extraction System,
Operating Unit No. 1, Cleburn Street Superfund Site,
Grand Island, Nebraska
January 2001 Quarterly Performance Report, Cleburn
Street Site, Operable Unit 2
1.4
PERSONS CONTACTED
The following individuals were present for the site visit:
Rob Blake, Black and Veatch
Matt Irmer, Geotechnical Services, Inc.
Mike McKinley, TapanAm
Mary Peterson, EPA Region 7
David Sanders, Black and Veatch
1.5
1.5.1
SITE LOCATION, HISTORY, AND CHARACTERISTICS
LOCATION
The Cleburn Street Well Superfund Site, named after a contaminated former public water supply well in
downtown Grand Island, Nebraska, encompasses 144 blocks of that metropolitan area. The site is divided
into the following five operable units
OU1 is a soil vapor extraction (SVE) system addresses the subsurface soil contamination from
the former One Hour Martinizing located on the corner of 4th and Eddy Streets;
OU2 is a pump-and-treat system that addresses the groundwater contamination associated with
the same facility;
OU3 and OU4 are monitored natural attenuation programs that address the groundwater
contamination associated with Liberty Cleaners and Ideal Cleaners, respectively; and
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OU5 addresses the soil and ground-water contamination associated with the former Nebraska
Solvents.
This RSE report pertains to OU2, as it is the only Fund-lead P&T system within the site, and also to OU1
as it relates to OU2. Contamination of the Cleburn Street well was first detected in April 1986, final
listing of the site on the National Priorties List (NPL) occurred on October 14, 1992. The Remedial
Investigation (RI) began in 1992 with an accompanying pumping system that extracted water with high
concentrations of PCE and discharged it to the sanitary sewer at 50 gallons per minute. Construction
completion of the current OU1 SVE and OU2 pump-and-treat systems occurred in March 1998.
The site layout with the identified contaminant sources and contaminant plume is depicted in Figure 1-1.
1.5.2 POTENTIAL SOURCES
The groundwater contamination at OU2 is predominantly tetrachlorethylene (PCE) and small quantities of
degradation products that stem from disposal practices at the One Hour Martinizing dry cleaners. In
addition, there are small concentrations of 1,1,1 Trichlorethane, that potentially stem from OU5 directly to
the west. PCE concentrations in groundwater beneath the One Hour Martinizing facility measured during
the Remedial Investigation were as high as 170,000 ug/L which exceeds the solubility of PCE. This
suggests the presence of freephase PCE which exists in the subsurface as a dense non-aqueous phase
liquid (DNAPL). As of January 2001, PCE concentrations in MW-2A were 140,000 ug/L. This
concentration is still indicative of DNAPL which serves as a continuing source of dissolved phase PCE.
Although the groundwater extraction wells screen from approximately 45 to 60 feet below land surface,
the DNAPL appears to be limited to the area around MW-2A and a depth of approximately 20 to 30 feet.
Smaller concentrations of BTEX (benzene, toluene, ethylbenzene, and xylene) are also found at the site
and are stipulated as contaminants of concern by the ROD. These contaminants were found during the
remedial investigation at OU5, but likely exist at OU2 due to leaks or spills at a former service station
once located directly across 4th Street to the north of the former One Hour Martinizing facility.
1.5.3 HYDROGEOLOGIC SETTING
Silty sands, sands, and gravelly sands with occasional thin clay layers extend from the surface to 90 feet
below the surface and are underlain by a clay aquitard that ranges from 144 to 153 feet thick. This
formation above the aquitard serves as the source of the public water supply and is the portion affected
by site-related contaminants. The groundwater underlying the site is, on average, 18 to 22 feet below the
surface and according to the RI flows in a 75' to the east of north at approximately 0.06 feet per day and
almost directly east when the Cleburn Street Well was in operation. This follows from an average
hydraulic conductivity of approximately 6 feet per day as determined by slug tests during the RI, a
gradient of 0.003, and a porosity of 0.3. It should be noted that a pumping test conducted during the
design stage with EW-1 and a few monitoring wells yielded a hydraulic conductivity of 0.24 feet per
minute (345 feet per day) which translates to a linear groundwater velocity of 3.5 feet per day.
Interpretations in the RI of soil borings suggest that the upper portions of the aquifer (between land
surface and a depth of 40 feet) consist of finer, less conductive materials than the medium to coarse
material present at 40 to 60 feet.
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1.5.4 DESCRIPTION OF GROUND WATER PLUME
The PCE groundwater plume originates at the location of the former One Hour Martinizing shop on the
corners of 4th and Eddy Streets and extends eastward toward and beyond the Cleburn Street well. As of
January 2001, the PCE concentration at MW-2A, which screens 20 to 30 feet below land surface, was
140,000 ug/L; however, other monitoring points in the immediate vicinity had much lower PCE
concentrations. The PCE concentration in EW-2, 20 feet to the side and screened from 45 to 60 feet
below land surface, registered only as high as 1,100 ug/L. MW-2B, which is located adjacent to MW-2A
but is 90 feet deep, had undetectable levels of PCE. The concentration in the Cleburn Street well, located
approximately 250 feet to the east was 70 ug/L, and concentrations to the north, south, and east of the
Cleburn Street well measured 10 ug/L or less. The portion of the plume beyond the Cleburn Street well is
not well-defined.
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2.0 SYSTEM DESCRIPTION
2.1 SYSTEM OVERVIEW
Remediation associated with the One Hour Martinizing facility consists of OU1, which is a State-lead
SVE system, and OU2, which is a Fund-lead pump-and-treat system. The building housing the former
shop has been divided into two sections. The section to the north along 4th Street is privately owned and
leased out to private businesses. The southern section houses an air stripper for treating the extracted
groundwater and the SVE system.
2.2 EXTRACTION SYSTEM
2.2.1 OU1 EXTRACTION SYSTEM
The OU1 extraction system consists of four SVE wells approximately 30 feet apart in a oriented in a line
between the front of the treatment building and Eddy Street. Each well is approximately 17 feet deep
with a 10-foot screening interval.
2.2.2 OU2 EXTRACTION SYSTEM
The OU2 extraction system consists of three groundwater extraction wells approximately 40 feet apart
and interspersed between the SVE wells. The groundwater extraction wells are approximately 55 to 60
feet deep with screened intervals of 15 feet, which differs from the design plan of 50 feet deep with
screened intervals of 25 feet.
2.3 TREATMENT SYSTEM
2.3.1 OU1 TREATMENT SYSTEM
The vapors from the SVE wells flow under negative ambient pressure through a moisture knockout
container, through an air-to-air heat exchanger that raises the temperature of the vapors to 90 F, through
two of six carbon units in a two series-three parallel carbon vessels system, and then into a Roots 50-
horsepower positive displacement blower. The vapors leave the blower hot and under positive ambient
pressure, flow through the above air-to-air heat exchanger where the heat is transferred to the incoming
vapors and discharged to the ambient air outside of the treatment building. The water resulting from
condensation in the system is sent through two liquid phase carbon units and is then discharged to the
storm sewer. The system is checked every week and serviced every two months.
2.3.2 OU2 TREATMENT SYSTEM
The water from the ground water extraction wells are pumped with submersible well pumps to the
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surface and through flow measuring and recording meters to the inlet of the air stripper. The air stripper
is a QED Model 16.4. with a fan and 7.5 HP motor. The treated water is discharged to the storm sewer.
The off gas from the air stripper is discharged through a stack to the ambient air outside of the treatment
building. The system is checked every week and during the quarterly sampling events.
2.4
MONITORING SYSTEM
Monitoring occurs quarterly in the extraction wells, the Cleburn Street well, and a select number of
monitoring wells. In addition, annual sampling events include sampling for PCE, BTEX, TCE, and 1,1,1
TCA in all site-related wells (except MW-7 which has been buried and inaccessible since the RI). Table
2-1 provides the results from the August 2000 annual sampling event and those locations that are sampled
quarterly.
Table 2-1: PCE concentrations from the August 2000 annual sampling event
Sampling Location
air stripper influent*
air stripper effluent*
EW-1*
EW-2*
EW-3*
Cleburn Street Well*
MW-2A*
MW-2B*
MW-8A
MW-8B
MW-9A
MW-10A
MW-10B
MW-11A
MW-11B
MW-12A*
MW-13A*
PCE concentration (ug/L)
460 and 600
1
700
820
45
110
41,000
undetected
undetected
undetected
11
undetected
undetected
29
undetected
110 and 170
undetected
* locations also sampled quarterly
Note: For locations with duplicate samples, both concentrations are presented.
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3.0 SYSTEM OBJECTIVES, PERFORMANCE AND CLOSURE
CRITERIA
3.1 CURRENT SYSTEM OBJECTIVES AND CLOSURE CRITERIA
The SVE system (OU1) is considered a containment remedy and was therefore transferred to State-lead
after a year of operation. The pump-and-treat system (OU2) is both a containment and restoration
remedy. The containment aspect of the remedy began during the Remedial Investigation with a single
well extracting contaminated water and discharging it without treatment to the sanitary sewer. The
restoration aspect of the remedy began with operation of the current pump-and-treat system for
"extraction of groundwater containing contaminants about MCLs". According to the ROD the
contaminants are all volatile organic carbons (VOCs) that were detected at least once. Included in the
ROD, however, is a provision to waive the cleanup levels through a Technical Impracticability (TI)
waiver if DNAPL is detected at the One Hour Martinizing source area.
In addition, a precedent has been sent by the remedies associated with the Liberty and Ideal Cleaners
source areas (OU3 and OU4). For these sources, where PCE concentrations are as high as 95 ug/L,
monitored natural attenuation is the current remedy as long as human health and the environment are
effectively protected.
3.2 TREATMENT PLANT OPERATION GOALS
Air emissions from the SVE and pump-and-treat air stripper must comply with Nebraska air regulations,
and the water effluent from the air stripper must comply with the permitting requirements under the
National Pollutant Discharge Elimination System (NPDES) Program.
3.3 ACTION LEVELS
Action must be taken if air emission or water effluent levels for the contaminants of concern violate either
Nebraska air regulations or the criteria of the NPDES Program.
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4.0 FINDINGS AND OBSERVATIONS FROM THE RSE SITE VISIT
4.1 FINDINGS
In general, the RSE team found the system to be well operated and maintained. The observations and
recommendations given below are not intended to imply a deficiency in the work of either the designers or
operators, but are offered as constructive suggestions in the best interest of the EPA and the public.
These recommendations obviously have the benefit of the operational data unavailable to the original
designers.
4.2 SUBSURFACE PERFORMANCE AND RESPONSE
4.2.1 WATER LEVELS AND CAPTURE ZONES
The current extraction system was designed based on a capture zone analysis using a modeling package
called Quickflow, parameters from the RI, and the hydraulic conductivity estimated from the pumping test
(0.24 feet/min). During operation the capture zone was reanalyzed with simple analytical techniques
based on actual flows rather than designed flows. The results suggested that capture is likely but that a
more conclusive analysis should be conducted. The capture zone of the groundwater extraction system
was being evaluated by site contractors with aquifer testing at the time of the RSE visit. The results of
this testing will presumably determine the capture zone of the three wells. The resulting capture zone will
likely include the source of contamination at the location of the former One Hour Martinizing shop but will
not include downgradient portions of the plume that have PCE concentrations as high as 100 ug/L.
The vertical variations in hydraulic conductivity may affect the capture zone. The documents reviewed by
the RSE team did not contain boring logs for the extraction wells; however, the RI does contain a cross-
section of the interpreted site geology from the boring logs (Figure 3-6 in the RI). This figure suggests
that in the vicinity of MW-2B (and therefore the extraction wells) fine to medium sand and even silty and
clayey fine sands are the predominant materials to a depth of 40 feet below land surface. From 40 feet to
60 feet, there appears to be a change to fine to coarse and medium to coarse sand. Based on discussion
during the RSE visit, extraction wells are approximately 60 feet deep with screened intervals of 15 feet.
If this is the case, the wells screen the coarser subsurface media therefore potentially extracting cleaner
water from deeper portions of the aquifer and not capturing the plume in the shallower portions.
4.2.2 CONTAMINANT LEVELS
PCE concentrations in MW-2A strongly suggest, if not assure, the presence of DNAPL that acts as a
continual source of dissolved phase PCE. The DNAPL appears to be limited to the upper portions of the
aquifer based the discrepancy in groundwater concentrations between MW-2A (41,000 ug/L in August
2000) and MW-2B (undetected in August 2000). MW-2A and MW-2B are located adjacent to one
another, but MW-2A has a depth of approximately 30 feet and MW-2B has a depth of approximately 90
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feet. Because the extraction wells screen from 45 to 60 feet below the surface, they are likely extracting
a significant amount of cleaner water from deeper portions of the formation rather than highly
contaminated water from the shallower portion of the formation. This is supported by the lower
concentrations in the extracted water. Table 2-1 shows that sampling of the extraction wells in August
2000 yielded concentrations ranging from 45 ug/L to 820 ug/L, a range which is substantially lower than
the 41,000 ug/L from MW-2A during the same sampling event.
The horizontal extent of the DNAPL has not clearly been defined upgradient of MW-2A due to the
presence of the building housing the treatment systems and the private wood-staining operation. The
operations of the One Hour Martinizing facility could have resulted in PCE contamination of the soils
directly beneath the building.
Concentrations of 1,1,1 TCA, BTEX, and other VOCs were detected in MW-2A and MW-12A as
recently as January 2001. While the pump-and-treat system addresses this contamination as stipulated in
the ROD, these constituents are not consistent with the operation of a dry cleaning facility. These
contaminants were detected in both soil and groundwater beneath the west parcel of the Nebraska
Solvents location during the Nebraska Solvents RI. While the 1,1,1 TCA at OU2 may have migrated
from the Nebraska Solvents site, the majority of BTEX present in the groundwater beneath OU2 likely
stems from leaks or spills at a former gasoline service station once located directly across 4th Street to the
north of the One Hour Martinizing facility.
4.3 COMPONENT PERFORMANCE
4.3.1 EXTRACTION-WELL PUMPS AND PIPING
The extraction wells are consistently running below design level of 40 gpm each. EW-1 is extracting
approximately 27 gpm, EW-2 is extracting approximately 20 gpm, and EW-3 is extracting approximately
36 gpm. During the RSE visit, these wells were throttled to reduce flow and EW-2 was cycling. This
suggests the possibility of well fouling. In addition, the well vaults need to be drained. Water in the vault
for EW-1 has almost risen to the well cap.
4.3.2 Am STRIPPER
The air stripper is well-maintained and has effectively removed PCE to concentrations below discharge
standards. The stripper has a high-high sump level and low air pressure alarm and shutdown to prevent
blower damage and discharge of untreated water. The air pressure in the stripper is monitored to
determine tray fouling, and the trays have required cleaning on a yearly basis.; however, the air flow rate
into the unit is not being measured. The air flow rate is not measured and therefore the air-to-water ratio
is unknown. The system appears to be running at a air-to-water ratio that is higher than required but not
at substantial cost.
4.3.3 Aero WASH SYSTEM
The acid wash system is not needed and has not been used. Acid and caustic, however, are stored
onsite.
10
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4.3.4 SVE BLOWER
The SVE blower is a Roots Model 418 J belt-drive rotary lobe positive displacement blower powered by a
50-horsepower designed to operate at 1,300 cubic feet per minute and a pressure drop equivalent to 9
inches of mercury. The blower is operating with the air intake valve open allowing the blower to take in a
large quantity of ambient air. The vacuum established on the well-side of the air intake is 5.25 inches of
mercury. No meter is installed to determine the current flow rate.
4.3.5 LIQUID AND VAPOR PHASE CARBON UNITS
Each of the six vapor phase carbon units contains 1,200 pounds of activated carbon, and each of the two
liquid phase carbon units contains 200 pounds of activated carbon. Carbon replacement is handled and
paid for by the State. Replacement of the lead vapor phase carbon units occurs approximately every 10
months based on weekly PID measurements. Replacement of the liquid phase carbon had not occurred
between the time of system operation and the RSE visit. Condensate from the SVE system could be
treated through the air stripper rather than the liquid phase carbon. This alteration should be made when
the liquid GAC is spent.
4.4 COMPONENTS OR PROCESSES THAT ACCOUNT FOR MAJORITY OF
COSTS
Total operating cost for OU2 is approximately $110,000 per year with approximately 58% of that going to
project management.
4.4.1 LABOR
Operator labor, which totals $1,750 per month, involves a weekly check of the OU2 system and the labor
associated with the quarterly and annual sampling events. In addition, project management from Black
and Veatch totals on average $5,400 per month, which appears high compared to project management
costs of approximately $3,500 per month for similar systems.
4.4.2 CHEMICAL ANALYSIS (ON AND OFF SITE)
Chemical analysis for OU2 is accomplished through the EPA Regional lab at no direct cost to the system.
4.4.3 NON-UTILITY CONSUMABLES AND DISPOSAL COSTS
There are no costs assumed by EPA for non-utility consumables or disposal costs. The acid and caustic
for the acid wash system are not used, and the carbon for the SVE system (OU1) is paid for by the State.
4.4.4 UTILITY COSTS
The EPA pays for the electricity used by both OU1 and OU2. The average monthly electric bill is $1,400,
and the average monthly gas bill is $600. The phones for OU1 and OU2 combined cost $125 per month.
11
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4.5 RECURRING PROBLEMS OR ISSUES
The system operates continuously with little or no problems.
4.6 REGULATORY COMPLIANCE
The water discharge criteria is regularly met. The air emissions are not regularly measured but are likely
well below those specified in air regulations.
4.7 TREATMENT PROCESS EXCURSIONS AND UPSETS, ACCIDENTAL
CONTAMINANT/REAGENT RELEASES
There are no recorded excursions of discharge or air emission standards. However, water obtained
during quarterly sampling is discharged into the storm sewer. Some of this water, especially that from
MW-2A, has high concentrations of PCE.
Prior to the treatment system construction, impacted groundwater was discharged to the sanitary sewer
without treatment. Discharges to the sanitary sewer could have resulted in spreading PCE contamination
if the sewer has leaks, which is typical of these systems.
4.8 SAFETY RECORD
The plant has an excellent safety record.
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5.0 EFFECTIVENESS OF THE SYSTEM TO PROTECT HUMAN
HEALTH AND THE ENVIRONMENT
5.1 GROUND WATER
The ROD stipulates institutional controls to prohibit the use of contaminated water for drinking and the
installation of private drinking wells in the vicinity of the site. In addition, the ROD mentions that due to
the shallow nature groundwater elevation, a number of unregistered private wells could exist within the
site. A city ordinance currently prohibits the installation of new wells in vicinity of the site. Also, in the
early stages of the remedy, EPA coordinated with the city to identify private wells in the area, and none
were found.
The Pine Street well, located approximately 1,500 feet downgradient, had not been contaminated at the
time of the RSE and provides public water during periods of heavy demand according to a public health
assessment by the U.S. Department of Health and Human Services, Agency for Toxic Substances and
Disease Registry (ATSDR) in March 26, 1997. The same ATSDR assessment reports that a private well
is located upgradient of the One Hour Martinizing source area and appears to be unaffected by site-
related contamination. The assessment also states that
Sampling data for other private wells in the site area were not available to ATSDR during the
development of this health assessment. ATSDR considers this a significant data gap because area
private wells, especially those located near the One Hour Martinizing location or the Cleburn Street
well, may be affected by site-related groundwater contaminants.
5.2 SURFACE WATER
Surface water is not threatened by site-related contamination. The Cleburn Street well is occasionally
operated to prevent high water levels. All treated water from OU2 is sent to the storm sewer which in
turn discharges to the Wood River 2.5 miles to the south. Site-related contamination of the Wood River
from OU2 discharge is unlikely as VOCs would tend to volatilize before reaching it.
Standing water in a subsurface traffic-light vault near the One Hour Martinizing facility, had high
concentrations of PCE in 1988. These concentrations have likely decreased with the operation of the
SVE system.
5.3 AIR
The mass of PCE released from OU2 is approximately 0.3 pounds per day as determined by data from
the January 2001 quarterly report and the following calculation:
13
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330ugPCE 80 gallons 1440 minutes 10~9 kg 2.2 Ibs 3.785 liters 0.32 pounds PCE
x x x x x
liter minute day ug kg gallon day
Therefore, the air emissions from these two operable units do not cause a threat to human health or the
environment. The shallow groundwater PCE concentrations in the immediate vicinity of OU2 are
relatively high, however, and could result in PCE vapors in the unsaturated zone beyond the reach of the
SVE system. These vapors could affect the air quality in basements or enclosed spaces located above the
groundwater plume. The ATSDR assessment reports, "No sampling data for VOCs in ambient air
(indoor or outdoor) at the site were available during the development of this public health assessment. For
indoor air, this is considered to be a significant data gap since VOCs in soil gas may accumulate inside
buildings (e.g., residences, businesses) at areas with significant groundwater and soil contamination (e.g.,
near One Hour Martinizing location)."
5.4 SOILS
There are no accessible contaminated soils associated with OU1 or OU2 as pavement and asphalt cover
the area. OU1 currently addresses subsurface soil contamination.
5.5 WETLANDS
There are no wetlands in the vicinity of OU1 and OU2.
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6.0 RECOMMENDATIONS
6. 1 RECOMMENDATIONS TO ENSURE EFFECTIVENESS
6.1.1 IMPROVE WELL-MAINTENANCE PROGRAM
The extraction wells are operating between 80 and 90 gpm, which is significantly lower than the 120 gpm
specified in the design. This lower operating rate is likely due to throttling of the pumps in each well and
also to well fouling, especially for EW-2. The operators should use Hach BART tests to determine the
nature of the fouling problem and the correct rehabilitation technique. When the proper technique is
identified, well rehabilitation should commence for those extraction wells that require it, and a quarterly
well-maintenance program may be necessary to prevent further fouling. In addition, during quarterly
sampling events, the specific capacity of each well could be measured to determine if the performance is
decreasing over time. BART tests and well rehabilitation for each fouled well could be accomplished for
approximately $2,000 including operator labor. Also, the quarterly well-maintenance program to prevent
future fouling could increase annual costs by approximately $2,000 per well per year. More information
about well maintenance can be found in USAGE Engineering Pamphlet EP 1 1 10-1-27 at
6.1.2 DETERMINE CAPTURE-ZONE EFFECTIVENESS
The capture zone of the extraction system was analyzed during design with the Quickflow modeling
package and during operation with simplistic analytic methods outlined in hydrogeological literature. While
the analysis done during design showed that current pumping rates would not provide adequate capture
for extraction wells placed 50 feet apart, the extraction wells are actually closer to 40 feet apart, and
simple analytical methods suggest this spacing and pumping rate are sufficient. To more thoroughly
analyze capture, the operators conducted further aquifer testing at the time of the RSE visit, and the
results from this test will be used to reevaluate the capture zone.
This testing and the subsequent analysis will likely show that the extraction wells are sufficiently spaced
horizontally to capture pollutants, but it will not provide sufficient information regarding vertical variations
in contamination and hydraulic conductivity. As demonstrated by the high PCE concentrations in MW-
2A, the "hot spot" of contamination occurs near MW-2A at a depth of approximately 20 to 30 feet.
However, the extraction wells reportedly screen from 45 to 60 feet, well below the contamination.
Furthermore, the RI interpretations of the boring logs suggested this deeper portion of the aquifer may be
more conductive than the upper portion near the "hot spot". It is this vertical variation in hydraulic
conductivity and the possible presence of a relatively impermeable layer that has prevented the DNAPL
from settling deeper into the aquifer. Thus, it is likely that despite potentially positive results from the
recent capture zone analysis by the operators, adequate capture may not be provided.
PCE concentrations downgradient of the extraction system as sampled from the Cleburn Street well,
MW-8A, MW-8B, MW-9A, MW-10A, and MW-10B have decreased or remained low possibly indicating
capture of the PCE source. However, these wells are more than 250 feet downgradient of the extraction
15
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system. Therefore, to determine if the extraction system is continuing to effectively contain the source
area, a monitoring-well couplet could be installed approximately 50 to 100 feet downgradient of the
extraction well array. One monitoring well in this couplet would screen from 20 to 30 feet deep (the
approximate depth of the contamination "hot spot") and the other would screen from 40 to 60 feet deep
(the approximate depth of the screening intervals for the extraction wells). The concentration trend in
each of these two wells over time would show whether or not contamination is captured by the extraction
well array. As it may take considerable time to evaluate the concentration trend it is beneficial to
measure water levels from these and all other site-related wells and to compare the results to those
expected based on known aquifer parameters, the locations of the extraction wells, and the pumping rates.
Drilling the two monitoring wells would cost approximately $10,000 and adding them to the quarterly
sampling program would cost approximately $1,000 per year. In addition, simple numerical modeling of
groundwater flow could be used to evaluate the measured water levels from the current and
recommended wells; however, such modeling would likely cost about $15,000.
It should be noted that buildings, roads, and other aspects of an urban environment may complicate drilling
of these wells, making this recommendation infeasible. In this case, MW-8A and MW-8B, which are
located approximately 250 feet downgradient of the extraction system, could be used as less favorable,
but feasible, sentinel wells. If a breach in the capture zone occurred, concentrations trends in these two
wells may reflect it after an appreciable amount of time. If additional analysis of the capture zone is
preferred, the simple numerical modeling suggested above could be conducted to evaluate water levels
measured from the current wells. Although this would provide some indication of capture, it would not be
as reliable as an evaluation including the two new recommended monitoring wells.
6.1.3 MODIFY WELL-SAMPLING PROTOCOL
The current well-sampling protocol, observed by the RSE team during the site visit, includes disposing of
purged water to the storm sewer and sanitary sewer. As a result of this protocol, water with high
concentrations of PCE, potentially over 100,000 ug/L, is released into the storm and/or sanitary sewer.
Because these sewers often have leaks, and this contamination could reenter the aquifer at another
location, purged water should be fed through the air stripper. Current bailing techniques result in water
with high turbidity, and this turbidity is detrimental to the air stripper. This turbidity could be eliminated in
one of two ways. First, the sampling could be accomplished with low-flow pumping. Purge water from
low-flow pumps have less turbidity, and this water could be directly fed into the air stripper influent. In
addition, using a low-flow pump should facilitate the sampling and should provide more representative
samples. Alternatively, the purged water from bailing could be dumped into the acid wash tank allowing
particles to settle. Once sufficient settling has occurred, the contents of the acid wash tank (i.e., the
purged water with no acid), could be fed through the air stripper.
6.1.4 REVIEW PREVIOUS SURVEYS OF PRIVATE WELLS IN AREA
The ROD specified "extraction of groundwater containing contaminants above MCLs". The current
system, however, does not address PCE contamination more than twenty feet downgradient of the
extraction well array. Assuming the PCE upgradient of the extraction wells is contained, the PCE
downgradient will eventually disperse and fall below MCLs. However, until that time, water near and
downgradient of the site should not be used for drinking. A city ordinance currently prohibits the
installation of new wells. Public records should be reviewed to ensure that wells installed prior to the
ordinance are not still operational, and previous surveys of wells in the area should be reviewed for
16
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completeness. If these initial reviews reveal the potential for operating wells in the area, further
investigation may be necessary.
6.1.5 CONDUCT SAMPLING OF INDOOR AIR AND STANDING WATER
The high PCE concentrations near the heart of the plume could result in PCE vapors entering nearby
buildings. Indoor air sampling should be conducted in the former building that housed One Hour
Martinizing shop and perhaps buildings directly across Eddy Street from the extraction system. In
addition, sampling for VOCs should be conducted in standing water found in the traffic box light just east
of the former One Hour Martinizing facility. Quarterly sampling for one year should cost approximately
$5,000 including labor. If contamination is found during this first year, this sampling could be added to the
quarterly sampling events in the future, potentially raising sampling costs (including labor) by
approximately $5,000 per year.
6.1.6 SAMPLE PINE STREET WELL FOR PCE
A public health assessment by the U.S. Department of Health and Human Services, Agency for Toxic
Substances and Disease Registry (ATSDR) in March 26, 1997 reported that the Pine Street well
continues to operate during periods of peak demand. It is possible that PCE at concentrations above
MCLs may, at some point, impact this well, and sampling for PCE at this location should occur quarterly
as it is downgradient of current PCE contamination. If PCE contamination of the well is found, well-
operation should be adjusted accordingly. Analytical costs for quarterly sampling of PCE and other
VOCs from this one location should cost under $500.
6.2 RECOMMENDATIONS TO REDUCE COSTS
6.2.1 COMBINE OPERATION OF OU1 AND OU2 AND REDUCE FREQUENCY OF PID
MEASUREMENTS
Geotechnical Services, Inc. (GSI) is contracted by Black and Veatch to maintain OU2 and by the
University of Nebraska at Kearney to maintain OU1. Labor costs could be reduced by having the
operators maintain both systems under the same contract and reducing the frequency of PID
measurements (done for carbon replacement) from weekly to monthly. With the reduction in PID
sampling, maintenance of both sites could be easily accomplished in a single visit. Thus, if GSI is currently
billing for two visits, this recommendation could yield savings of approximately $1,500 per month. If a
single contract is infeasible under current program guidelines, the separate contracts should be
coordinated such that operation and maintenance costs reflect a single site visit to address both operable
units.
6.2.2 REPLACE SVE BLOWER WITH A SMALLER, MORE EFFICIENT UNIT
The SVE blower is rated at 50 horsepower and has a capacity to move 1,300 cubic feet per minute with a
pressure drop of 9 inches of mercury. However, the blower is operating with the air intake valve open
and a vacuum at the well heads of 5.25 inches of mercury. The air flow rate should be measured, and
based on those results, a 25 horsepower blower could be installed so that the energy used to run the
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blower is used to move only air from the subsurface and not clean air from the air intake valve. A 25
horsepower blower cost approximately $15,000 but would use half of the electricity of the 50 horsepower
blower which would save approximately $1,000 per month in electricity costs.
6.2.3 CONSIDER REDUCTIONS IN PROJECT MANAGEMENT COSTS
The project management costs associated with this site are on average $5,400 per month, which translates
to approximately $65,000 per year or 58% of the system O&M costs. This appears high given the project
management responsibilities associated with this system and also appears high compared to project
management costs at similar systems. The project management cost therefore should be compared with
the associated responsibilities to see if the cost can be reduced. The RSE team did not attempt to
quantify potential savings.
6.3 TECHNICAL IMPROVEMENT
6.3.1 MEASURE SVE WELL PARAMETERS
The air flow rate and PCE concentrations from each of the SVE wells should be measured to inform the
site managers of the mass removed from each well. This information could be used to optimize the SVE
system if it is found that the majority of mass is coming from one or two of the four SVE wells. PCE
concentrations are measured with PID weekly; however, the contracted team from the University of
Nebraska at Kearney report that the PID measurements show broad uncertainties. Thus, the
concentrations should be measured and reported with more exact techniques such as gas
chromatography. While gas chromatography may already be used, the results were not available in the
2000 OU1 annual report reviewed by the RSE team.
In addition, the vacuum induced by the SVE system should be measured in neighboring wells that at least
partially screen the vadose zone. This information would indicate the SVE capture zone. This is
especially important if an air sparging system is implemented (See Section 4.1).
Installing pitot tubes at each of the SVE well heads would cost less than $500 and measuring the induced
vacuum in a few neighboring wells could be added to the quarterly sampling events for a nominal cost.
6.3.2 TREAT SVE CONDENSATE WITH AIR STRIPPER RATHER THAN CARBON
The condensate from the SVE system is currently treated with activated carbon. This water could be
collected and sent through the air stripper thereby eliminating the need for the liquid phase carbon units.
This should be done when the liquid phase carbon is spent. It will cost approximately $500 for the
associated changes, but eliminating replacement of the liquid phase carbon units will offset this cost.
6.3.3 REFORMAT QUARTERLY PERFORMANCE REPORTS
The quarterly performance reports provide sample information in tables and in concentration vs. time
plots. While the data is also summarized in the text, this text does not provide additional analysis beyond
these tables and figures. The text should be used to highlight changes or note trends so that site managers
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can identify them more easily. For example, the 1999 annual report has four instances in which influent
PCE concentrations to the vapor-phase carbon units of the SVE system were higher than the
concentrations from the SVE wells. The concentrations were reported in the text, but the anomaly was
not explained. The quarterly performance reports should also include updated plume maps rather than
reprinting the same plume map from 1999.
6.3.4 DRAIN WATER FROM EXTRACTION-WELL VAULTS
All three of the extraction well vaults had significant amounts of water in them. In EW-1, the water was
almost to the level of the well cap. The vaults should be drained and retrofitted so that rainwater does not
accumulate in them. Draining the vaults and retrofitting them would cost approximately $1,500.
6.3.5 SAMPLE MONITORING WELLS FOR ADDITIONAL PARAMETERS
PCE is known to undergo reductive dechlorination in reduced environments. Measurements of oxidation-
reduction potential (ORP), dissolved oxygen (DO), dissolved organic carbon (DOC), sulfate (SO4~),
nitrate (NO3~), and dissolved iron will help determine the potential for reductive dechlorination. These
measurements could easily be made with field test kits and reported during the quarterly sampling events
for additional analytical costs of $1,000 per year.
6.4. RECOMMENDATIONS TO GAIN SITE CLOSEOUT
6.4.1 INVESTIGATE USE OF Am SPARGING
The primary issue of concern at the site is the presence of DNAPL as indicated by the high dissolved
concentrations of PCE in MW-2A. The DNAPL could be limited to the area immediately surrounding
MW-2A, but as no soil probes were done under the One Hour Martinizing building, the extent of the
DNAPL under the building is not known. Whatever the extent, the current pump-and-treat and SVE
system will not eliminate this continuing source of dissolved phase PCE. As a result, a more aggressive
approach is required. A cost-effective approach is to install and operate an air sparging system with
sparging wells at approximately 20 to 30 feet deep. The sparged air would help volatilize the DNAPL and
transport it to the vadose zone where the SVE system can remove it. The extent and design of this
system would depend on the extent of DNAPL.
A small geoprobe should be used to determine the extent of DNAPL in the area near MW-2A and under
the building. For approximately $5,000 the geoprobe could be used for one or two days to sample
approximately 10 locations. In the process, the geoprobes would also provide pertinent information
regarding site stratigraphy, which is important as it helps identify the preferential flow paths of the
sparged air. Care must be taken to ensure that PCE laden air is not transported beyond the reach of the
current SVE system. Implementing this system would require drilling one or more air sparging wells,
installing an air compressor and the associated piping, and running tests. Operation requirements would
be similar to that of the air stripping or SVE system. A sparging system with proper testing, controls, and
one well should cost approximately $50,000 to install with each additional well costing approximately
$5,000. Operation of the air sparging system, including reporting and additional project management,
would increase the annual costs of the system, perhaps by $10,000, but it would also shorten the operating
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lifetime of the pump-and-treat system.
6.4.2 DEVELOP AN EXIT STRATEGY
An exit strategy should be developed for the site. This strategy would begin with aggressive removal of
the DNAPL. Once this continuing source of dissolved phase PCE has been removed, the site managers
should be begin to consider monitored natural attenuation (MNA). OU3 and OU4 with PCE
concentrations as high as 95 ug/L, currently have MNA as the remedy. With this precedent, it is
reasonable to assume that MNA could be used at OU2 once PCE concentrations are consistently below
95 ug/L.
In addition, the contaminants other than PCE and its degradation products should not affect the operation
and closure of OU2 as they are most likely not associated with the OU2 source. Rather, the RI from
OU5 (Nebraska Solvents) indicates that the west parcel of the Nebraska Solvents property is the most
likely source of these contaminants. Operation of the pump-and-treat system at OU2 may, however, be
required as part of the remedy for OU5.
6.5 UNUSED GOVERNMENT-OWNED EQUIPMENT
The acid wash system, and the associated chemicals on site, are not used for the current system. If the
acid wash tank is not used in the disposal of sampling water (see Section 6.1.3), it and the other parts of
the acid wash system could be used at another site. USAGE currently has a program designed to help
the transfer of unused government-owned equipment from Fund-lead sites to other Fund-lead sites where
that equipment can be used. The contact for this program is
Lindsey K. Lien, PE
U.S. Army Corps Engineers
12565 West Center Road
Omaha, NE 68144-3869
(402) 697-2580
Lindsey.K.Lien@nwd02.usace.army.mil
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7.0 SUMMARY
The observations and recommendations given below are not intended to imply a deficiency in the work of
either the designers or operators, but are offered as constructive suggestions in the best interest of the
EPA and the public. These recommendations obviously have the benefit of the operational data
unavailable to the original designers.
The RSE process is designed to help site operators and managers improve effectiveness, reduce operation
costs, improve technical operation, and gain site closeout. Recommendations to improve effectiveness
include rehabilitating fouled wells, analyzing and possibly improving the capture zone, modifying the
current well-sampling program, surveying for local private wells, and conducting indoor sampling.
Recommendations to reduce costs include combining the labor contract for OU1 and OU2 and replacing
the existing SVE blower with a smaller, more efficient one. Recommendations for technical improvement
include measuring additional operating parameters of the SVE system, treating condensate water from the
SVE system with the air stripper, reformatting the quarterly reports, and draining water from the
extraction-well vaults. Regarding site close out, the report recommends investigating and possibly
implementing the use of air sparging to address the DNAPL on site and developing an exit strategy based
on precedents set in other operating units.
Tables 7-1 summarizes the costs and cost savings associated with each recommendation. Both capital
and annual costs are presented. Also presented are the expected change in life-cycle costs are over a 30-
year period for each recommendation both with discounting (i.e., net present value) and without it.
Table 7-2 summarizes the estimated life-cycle costs of
the current system,
the current system with implementation of the recommendations excluding air sparging, and
the current system with implementation of all recommendations including air sparging.
For the purposes of demonstrating potential cost savings associated with the air sparging system, it is
assumed that the air sparging system decreases the lifetime of the system by half, which may be an
optimistic. Therefore, a 30-year period is used for the life-cycle of the systems without air sparging and a
15-year period is assumed for the life-cycle of the system with air sparging.
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Table 7-1. Cost summary table for individual recommendations
Recommendation
6. 1.1 Rehabilitate fouled
extraction wells
6.1.2 Determine capture -zone
effectiveness with sampling
6. 1 .3 Modify well-sampling
program
6.1.4 Survey local private wells
6. 1 .5 Conduct indoor air
sampling
6.1.6 Sample Pine Street well for
PCE
6.2. 1 Combine operator labor for
OU1 and OU2
6.2.2 Replace blower for OU1
6.2.3 Consider reducing project
management costs
6.3. 1 Measure SVE well
parameters
6.3.2 Treat SVE condensate
with air stripper
6.3.3 Reformat Quarterly
Performance Reports
6.3.4 Drain water from
extraction- well vaults
6.3.5 Sample wells for additional
parameters
6.4. 1 Investigate and implement
air sparging
6.4.2 Develop an exit strategy
Reason
Effectiveness
Effectiveness
Effectiveness
Effectiveness
Effectiveness
Effectiveness
Cost reduction
Cost reduction
Cost reduction
Technical
improvement
Technical
improvement
Technical
improvement
Technical
improvement
Technical
improvement
Gain site close
out
Gain site close
out
Estimated Change in
Capital
Costs
$6,000
$10,000
$0
$0
$5,000
$0
$0
$15,000
not
quantified
$500
$500
$0
$1,500
$0
$55,000
$0
Annual
Costs
$6,000
$1,000
$0
$0
$0
$500
($18,000)
($12,000)
not
quantified
$0
($100)
$0
$0
$1,000
$10,000
$0
Life-cycle
Costs*
$186,000
$40,000
$0
$0
$5,000
$15,000
($540,000)
($345,000)
not
quantified
$500
($2,500)
$0
$1,500
$30,000
see Table 7-2
Cf)
^)\J
Life-cycle
Costs **
$102,700
$26,100
$0
$0
$5,000
$8,100
($290,500)
($178,700)
not
quantified
$500
($1,100)
$0
$1,500
$16,100
see Table 7-2
$0
Costs in parentheses imply cost reductions.
* assumes 30 years of operation with a discount rate of 0% (i.e., no discount).
** assumes 30 years with a discount rate of 5% and no discounting in the first year.
22
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Table 7-2. Cost estimates for systems with and without implemented recommendations
Current P&T system
P&T system with
recommendations
(no air sparging)
P&T system with all
recommendations
including air sparging
Description
Current
Moderate
Aggressive
Capital
Costs
$0
$38,500
$93,500
Annual
O&M Costs
$110,000
$88,400
$98,400
Estimated Life-
cycle Costs*
$3,300,000
$2,690,500
$1,569,500
Estimated Life-
cycle Costs**
$1,775,500
$1,463,000
$1,165,900
Note: 30 years of operation is assumed for systems without air sparging, and 15 years of operation is assumed for
the system with air sparging
* assumes a discount rate of 0% (i.e., no discount).
** assumes a discount rate of 5% and no discounting in the first year.
23
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FIGURES
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FIGURE 1-1. SITE LAYOUT SHOWING THE CONTAMINANT SOURCES, GROUNDWATER EXTRACTION WELLS, SVE WELLS, AND THE 1999 PCE PLUME.
jcoiB ST^|ELLFORMER NEBRASKA STBEET WELL
SOLVENT COMPANY
FEET
(Figure compiled from Figure 1 of the Cleburn Street Well Remedial Investigation Reoprt, Phase III
Addendum, Sverdrup, 1993 and from Figures from the January 2001 Quarterly Performance
Report, Cleburn Sreet Well Site, OU2, Black and Veatch, March 9, 2001.)
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Solid Waste and
Emergency Response
(5102G)
542-R-02-008k
October 2002
vwwv.clu-in.org/rse
www.epa.gov/tio
U.S. EPA National Service Center
for Environmental Publications
P.O. Box 42419
Cincinnati, OH 45242-2419
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