REMEDIATION SYSTEM EVALUATION
BAYOU BONFOUCA SUPERFUND SITE
SLIDELL, LOUISIANA
Report of the Remediation System Evaluation,
Site Visit Conducted at the Bayou Bonfouca Superfund Site
February 20-21,2001
Final Report Submitted to Region 6
June 29, 2001
LU
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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-02-008f) 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 54 acre Bayou Bonfouca Superfund Site, located at the western edge of Slidell, Louisiana, is
impacted by creosote contamination from a wood-treating plant that operated between 1872 and!970.
Surface water bordering the site on the downgradient sides also was affected by creosote. Source
removal operations costing approximately $140 million began in November 1993 and were completed
in July 1995. These operations included excavation of the plant process area, dredging of the bayou
and Eastern Drainage Channel, and onsite incineration and storage of the recovered materials. A
pump-and-treat system, initially installed in July 1991 and modified between 1997 and 2000, remains at
the site to reduce or eliminate the potential for ingestion of carcinogens in groundwater and control the
migration of polyaromatic hydrocarbon (PAH) contamination in the Shallow Artesian Aquifer.
During the site visit for the Remediation System Evaluation (RSE), the site managers indicated that
their primary focus has been to remove the non-aqueous phase liquid (NAPL) to the extent
practicable, although it should be noted that one of the three extraction well arrays, while designed to
potentially remove freephase product, is operated primarily for control of dissolved constituents.
This pump-and-treat system, consisting of 44 wells that collectively extract approximately 16 gallons
of total fluid per minute, collects nearly 6000 gallons of creosote per year in addition to dissolved
phase PAHs. After ten years of operation under EPA oversight, this site will be turned over to the
State of Louisiana on July 11, 2001. As specified in the National Contigency Plan (NCP) and the
Superfund State Contract, the State is required to continue O&M activities at the site for a minimum
of 30 years during which time the EPA will continue to provide regulatory oversight.
The Remediation System Evaluation (RSE) team found a smoothly running treatment system and an
extremely well-operated and maintained site. The following recommendations are suggested to
improve system effectiveness:
• Containment of the free and dissolved phase contamination has not been rigorously evaluated
at the site and may in fact be impossible to evaluate and/or achieve because of the extent of
the contaminant plumes, the transient nature of pumping, and the limitation of extraction rates
that are implemented in order to control subsidence. Lack of containment would be
inconsistent with the ROD objective to "control the migration of PAH contamination in the
shallow artesian aquifer and other aquifers". An expanded groundwater monitoring program
with additional monitoring wells is strongly recommended to help evaluate containment,
delineate the plume, and determine cleanup progress over time. Suggestions are provided for
locations of additional wells; however, it should be noted that while the recommended
sampling can help evaluate capture, it is not sufficient to determine if the remedy, especially
that portion addressing the offsite plume, is consistent with the ROD objective of controlling
contaminant migration.
• Because of the potential for site contaminants to discharge from the subsurface to the bayou
over time, the RSE team recommends that the site managers review the State sampling
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program for surface water, benthics, and fish to determine 1) the effectiveness of this
sampling program in detecting site-related contamination and 2) the effectiveness of the
remedial action in limiting migration of site-related contaminants into the bayou. In addition,
the RSE team recommends that "no swimming" signs be displayed at appropriate locations
along the bayou to indicate the current swimming advisory posed on the State website
(http://www.deq.state.la.us/surveillance/mercury/fishadvi.htm).
These recommendations might require approximately $15,000 in capital costs and might increase
annual costs by approximately $6,500 per year.
The following recommendations are suggested to reduce life-cycle costs:
• The sampling of contaminants in four extraction wells can be eliminated without sacrificing
effectiveness as this current sampling program does not delineate the plume or reveal the
progress toward cleanup (potential savings of $10,800 per year).
• The plant operator should reinvestigate the recycling of recovered creosote which could save
disposal costs of $22,600 annually. Obstacles may include meeting product specifications
and/or reluctance to take material from a Superfund site; however, the option should
nevertheless be pursued to see if the obstacles can be overcome. Indemnification of the
facility that takes the material or incentives may help avoid these obstacles.
These savings could offset the extra costs associated with recommendations to improve system
effectiveness.
Finally, the RSE revealed that the ROD does not provide a clear exit strategy. Given that the ROD
stipulates cleanup with the pump-and-treat system to the lowest technically feasible limit,
consideration should be given to the fate of the system when the recovery rate of NAPL
contamination is significantly and consistently lower than the present rate. Even with minimal
recovery of freephase product, it is likely that NAPL remaining in the subsurface could serve as
continuing source of dissolved phase contamination, and the system may or may not need to continue
operating to contain this dissolved phase plume.
A summary of recommendations, including estimated costs and/or savings associated with those
recommendations is presented in Section 7.0 of the report.
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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
USEPA Technology Innovation
Office
(USEPA TIO)
USEPA Office of Emergency and
Remedial Response
(OERR)
GeoTrans, Inc.
(Contractor to USEPA TIO)
Army Corp of Engineers:
Hazardous, Toxic, and Radioactive
Waste Center of Expertise
(USAGE HTRW CX)
Key Contact
Kathy Yager
Paul Nadeau
Rob Greenwald
Dave Becker
Contact Information
2890 Woodbridge Ave. Bldg. 18
Edison, NJ 08837
(732) 321-6738
Fax: (732) 321-4484
yager.kathleen@epa.gov
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Mail Code 5201G
phone: 703-603-8794
fax: 703-603-9112
nadeau. paul@epa. gov
GeoTrans, Inc.
2 Paragon Way
Freehold, NJ 07728
(732) 409-0344
Fax: (732) 409-3020
rgreenwald@geotransinc. com
12565 W. Center Road
Omaha, NE 68144-3869
(402) 697-2655
Fax: (402) 691-2673
dave.j.becker@nwd02.usace.army.
mil
111
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The project team is grateful for the help provided by the following EPA Project Liaisons.
Regionl Darryl Luce and Larry Brill
Region 2 Diana Curt
Region 3 Kathy Davies
Region 4 Kay Wischkaemper
Region 5 Dion Novak
Region 6 Vincent Malott
Region 7 Mary Peterson
Region 8 Armando Saenz and Richard Muza
Region 9 Herb Levine
Region 10 Bernie Zavala
They were vital in selecting the Fund-lead P&T 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 111
TABLE OF CONTENTS v
1.0 INTRODUCTION 1
1.1 PURPOSE 1
1.2 TEAM COMPOSITION 2
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 3
1.5.3 HYDROGEOLOGIC SETTING 4
1.5.4 DESCRIPTION OF GROUND WATER PLUME 4
2.0 SYSTEM DESCRIPTION 5
2.1 SYSTEM OVERVIEW 5
2.2 EXTRACTION SYSTEM 5
2.3 TREATMENT SYSTEM 5
2.4 MONITORING SYSTEM 6
3.0 SYSTEM OBJECTIVES, PERFORMANCE AND CLOSURE CRITERIA 7
3.1 CURRENT SYSTEM OBJECTIVES AND CLOSURE CRITERIA 7
3.2 TREATMENT PLANT OPERATION GOALS 7
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 9
4.2.2 CAPTURE ZONES 9
4.2.3 CONTAMINANT LEVELS 10
4.3 COMPONENT PERFORMANCE 10
4.3.1 WELLS AND PUMPS 11
4.3.1.1 ARRAY 2 11
4.3.1.2 ARRAY IA 11
4.3.1.3 ARRAY 3 12
4.3.1.4 SUBSIDENCE 12
4.3.2 AIR COMPRESSORS 12
4.3.3 OIL/WATER SEPARATOR 12
4.3.4 FILTER FEED TANK 13
4.3.5 SAND FILTERS 13
4.3.6 OLEOPHILIC FILTER 13
4.3.7 GRANULAR ACTIVATED CARBON UNITS 13
4.3.8 POST AERATION TANK 13
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4.3.9 BACKWASH TANK 14
4.3.10 RECOVERED AND SKIMMED OIL TANK 14
4.3.11 STORMWATER SUMP 14
4.3.12 TOTAL ORGANIC CARBON (TOC) SAMPLER 14
4.3.13 AIR DRYER SYSTEM 15
4.3.14 AIR BLOWER 15
4.3.15 SEQUESTERING/CHELATING AGENT 15
4.4 COMPONENTS OR PROCESSES THAT ACCOUNT FOR MAJORITY OF COSTS 15
4.4.1 UTILITIES 15
4.4.2 NON-UTILITY CONSUMABLES AND DISPOSAL COSTS 15
4.4.3 LABOR 15
4.4.4 CHEMICAL ANALYSIS 16
4.4.5 OTHER COSTS 16
4.5 RECURRING PROBLEMS OR ISSUES 16
4.6 REGULATORY COMPLIANCE 16
4.7 TREATMENT PROCESS EXCURSIONS AND UPSETS, ACCIDENTAL CONTAMINANT/REAGENT
RELEASES 16
4.8 SAFETY RECORD 16
5.0 EFFECTIVENESS OF THE SYSTEM TO PROTECT HUMAN HEALTH AND THE ENVIRONMENT 17
5.1 GROUND WATER 17
5.2 SURFACE WATER 17
5.3 AIR 18
5.4 SOILS 18
5.5 WETLANDS AND SEDIMENTS 18
6.0 RECOMMENDATIONS 19
6.1 RECOMMENDED STUDIES TO ENSURE EFFECTIVENESS 19
6.1.1 DELINEATE PLUME AND EVALUATE CAPTURE ZONE OF EXTRACTION WELL ARRAYS .. 19
6.1.2 SAMPLING OF SURFACE-WATER, SEDIMENT, BENTHICS, AND FISH 20
6.2 RECOMMENDED CHANGES TO REDUCE COSTS 21
6.2.1 ELIMINATE SAMPLING PROGRAM OF CURRENT EXTRACTION WELLS 21
6.2.2 REINVESTIGATE RECYCLING OF COLLECTED CREOSOTE 21
6.3 MODIFICATIONS INTENDED FOR TECHNICAL IMPROVEMENT 21
6.3.1 PERIODIC CHECKS AND REPORTING OF NAPL RECOVERY IN INDIVIDUAL WELLS 21
6.3.2 MONTHLY EVALUATION OF DATA 22
6.3.3 CLARIFY ROLE OF TOC MEASUREMENTS FOR CARBON CHANGE OUT 22
6.3.4 INVESTIGATE INCREASED EXTRACTION RATES 22
6.4 MODIFICATIONS INTENDED TO GAIN SITE CLOSE-OUT 22
6.4.1 ESTABLISH EXIT STRATEGY AND CLOSURE CRITERIA 22
7.0 SUMMARY 24
List of Tables
Table 3-1. Action levels
Table 7-1. Cost summary table
List of Figures
Figure 1-1. Site layout showing areas of contamination and well locations.
Figure 1-2. Profile of bayou and stratigraphy
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" review), identify
cost savings through changes in operation and technology, assure clear and realistic remediation goals
and an exit strategy, and verify adequate maintenance of Government owned equipment.
The Bayou Bonfouca Superfund Site was chosen based on initial screening of the pump-and-treat
systems managed by USEPA Region 6 and discussions with the Project Liaison for that Region. This
site has relatively high operation costs and a long projected operating life relative to other Fund-lead
P&T systems in the Region. 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 Bayou Bonfouca and other Fund-lead
P&T systems throughout the nation will also be prepared and will identify lessons learned and typical
costs savings.
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1.2
TEAM COMPOSITION
The team conducting the RSE consisted of the following individuals:
Frank Bales, Chemical Engineer, USAGE, Kansas City District
Rob Greenwald, Hydrogeologist, GeoTrans, Inc.
Peter Rich, Civil and Environmental Engineer, GeoTrans, Inc.
Doug Sutton, Water Resources Engineer, GeoTrans, Inc.
1.3
DOCUMENTS REVIEWED
Author
US EPA
US EPA
USAGE, Kansas City
District
M.C. Anthon Waterwell
Contractor
M.C. Anthon Waterwell
Contractor
US EPA
US EPA
CH2MHill
US EPA
USAGE, Tulsa and
New Orleans Districts
IT Corporation
Date
3/31/1987
2/5/1990
9/1990
1990
1990
7/20/1995
9/1996
9/29/1997
9/30/1997
12/1999
12/2000
Title/Description
Record of Decision, Bayou Bonfouca Superfund Site,
Slidell, LA, March 31, 1987
Explanation of Significant Differences
Section 01810 Groundwater Operation and
Maintenance
Well installation logs. Well no 2-1 through 2-23
Well installation logs. Well no SM-1 through SM-9
Amendment to the Record of Decision, Bayou
Bonfouca Superfund Site, Slidell, LA, July 1995
Groundwater Remedial Action, Five- Year Review,
Bayou Bonfouca Superfund Site, Slidell, LA
Response Action Contract, US EPA Regioin 6,
Performance Evaluation Report for Shallow Artesian
Aquifer Remediation
Preliminary Close Out Report, Bayou Bonfouca
Superfund Site, Slidell, LA
95% Design Submittal, Groundwater Extraction Wells
and Groundwater Treatment System Modifications
(Phase 2), Bayou Bonfouca Superfund Site, Slidell,
Louisiana
Bayou Bonfouca Groundwater Remediation Monthly
Operational Report, November 1, 2000 through
November 30, 2000
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IT Corporation
IT Corporation
??
12/2000
1/2001
??
Groundwater Extraction Wells and Groundwater
Treatment System Modifications (Phase 2), Bayou
Bonfouca Superfund Site, Slidell, LA, Draft Final
Report
Bayou Bonfouca Groundwater Remediation Monthly
Operational Report, December 1, 2000 through
December 31, 2000
Daily Maintenance Checklist
1.4
PERSONS CONTACTED
The following individuals were presetn for the site visit:
Lee Guillory, Construction Manager, USAGE, New Orleans District
Jim Montegut, Project Engineer, USAGE New Orleans District
Alan Gradet, Project Manager, The IT Group
Rick Tibbs, Plant Operator, The IT Group
Rich Johnson, Louisiana Department of Environmental Quality
Katrina Coltrain, RPM, EPA Region 6
Vincent Malott, EPA Region 6, served as the project liaison for the Region.
1.5
1.5.1
SITE LOCATION, HISTORY, AND CHARACTERISTICS
LOCATION
The site is located off West Hall Avenue in Slidell, Louisiana, which is approximately 50 miles
northeast of New Orleans. The site occupies about 54 acres and is bounded by Bayou Bonfouca to
the south, drainage channels to the east and west, and West Hall Avenue to the north. Lake
Ponchartrain is approximately 7.5 miles downstream of the site. Zones of free and dissolved phase
creosote have been observed and are being extracted from the Shallow Artesian Aquifer below the
site and below private property on the opposite shore of the bayou. The site layout is shown on Figure
1-1 which illustrates estimated zones of contamination.
1.5.2
POTENTIAL SOURCES
The Bayou Bonfouca Superfund Site addresses contamination resulting from a creosote works facility
that operated from 1872 to 1970 when a fire destroyed the plant. Numerous spills of creosote onto
the plant property and into the bayou occurred through the years of operation, and a large spill
occurred with the fire in 1970. The site remedy included dredging and onsite incineration of the
contaminated sediments of the bayou, and extraction and treatment of the contaminated groundwater.
Creosote is present in the groundwater in the former process area due to previous handling processes
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that likely included drip pads, wastewater lagoons, storage and application areas. Creosote was also
discharged to the Eastern and Western Drainage Channels and NAPL now exists in the groundwater
to the west of the Bayou. Based on site investigation, both onsite and offsite areas have enough
NAPL present to warrant pumping. Three additional areas of dissolved and free phase creosote (see
Figure 1-3 of the 1997 Performance Evaluation Report) were located in the surficial water bearing
zone during site activities. Creosote is not being removed from these areas due to lesser volumes.
1.5.3 HYDROGEOLOGIC SETTING
Groundwater occurs in perched water tables in surficial sediments (2 to 9 feet in thickness), due to
infiltration from rainfall, and permanently in four other distinct zones: the upper cohesive unit (10 to 20
feet in thickness), Shallow Artesian Aquifer (9 to 16 feet in thickness), lower cohesive unit (8 to 28
feet in thickness), and Deep Artesian Aquifer (more than 10 feet in thickness). Materials range from
clay in the cohesive units to silt and medium-grained sand in the aquifers. The cohesive units function
as aquitards due to their reduced permeabilities and groundwater flow occurs through the Shallow and
Deep Artesian Aquifers toward the bayou. Without pumping, the water table is generally within 10
feet of the surface and varies up to a foot with tidal fluctuations in the bayou. A cross section
showing the stratigraphy is presented in Figure 1-2. The majority of the free and dissolved phase
creosote occurs in the Shallow Artesian Aquifer, which has reported hydraulic conductivities ranging
from approximately 1 to 20 feet per day. Groundwater velocities in the Shallow Artesian Aquifer are
estimated at 7 to 35 feet per year toward the bayou and drainage channels.
1.5.4 DESCRIPTION OF GROUND WATER PLUME
Free and dissolved phase creosote occurs in the Shallow Artesian Aquifer directly below the process
area, adjacent to the eastern drainage channel, and across the bayou underneath private property.
The estimated zones of contamination are shown in Figure 1-1. Sampling for PAHs to the east of the
property has not likely occurred since the initial Remedial Investigation. Also, because the monitoring
and extraction wells in the offsite plume to the west of the bayou are located for creosote removal,
they are not in the position and are not intended to delineate the boundaries of the plume.
During the Remedial Investigation, no contamination was found in the Deep Artesian Aquifer. The
current extent office and dissolved product beneath the bayou is unknown. The dredging and
excavation of the bayou that occurred between 1993 and 1995 stopped at a predetermined depth of
about 6 inches into the upper cohesive unit or at the depth where the interpolated PAH concentration
(from prior investigations) was less than 1,300 ppm. Crushed limestone backfill was then placed in
the bayou to return it to its original depth. Sampling of the bayou sediments and water are conducted
by the State of Louisiana and is not part of the site activities.
During the Remedial Investigation free and dissolved phase creosote were detected in the surficial
water bearing zone at two points along the Western Drainage Channel and at one point downstream
along the bayou. These were not addressed in the ROD and are not affected by the treatment
system.
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2.0 SYSTEM DESCRIPTION
2.1 SYSTEM OVERVIEW
The first objective of the pump-and-treat system is to recover free phase creosote from beneath the
site in the Shallow Artesian Aquifer by extracting oil bearing groundwater from recovery wells and
pumping this contaminated water through the treatment system. A second objective is to recover
dissolved and free phase creosote oil from the offsite area across the bayou. As groundwater is
extracted, offsite surface subsidence is avoided by maintaining the groundwater elevation at or above
4 feet below mean sea level (-4 feet MSL). Recovered creosote is disposed at a TSD facility. The
treated groundwater is discharged to the bayou.
The system is comprised of the following components:
• extraction well Arrays la, 2, and 3 (a total of 44 extraction wells)
• treatment building
• collection system piping and underground conduits
• groundwater and free phase treatment system (chelating agent, oil/water separator, solids
removal filters, organic removal filter, associated tankage)
• air compressor for plant and recovery pumps
• control system for recovery system and treatment system
2.2 EXTRACTION SYSTEM
The original on-site groundwater remediation system at the Bayou Bonfouca Superfund Site included
two networks of extraction wells, Array 1 and Array 2, installed in July of 1991. The location of the
Array 1 network was within the landfill location required for the source removal action. Array 1 wells
were removed during the soils remedial action. Array 2, which consists of 22 wells, remains in place
and is operating. After the 1997 investigation, it was recommended that another array of extraction
wells be installed to take the place of Array 1. Array la, which consists of 12 wells, was installed in
2000 downgradient of the creosote plume underneath the onsite landfill. Array 3, which consists of 10
wells, was also installed to capture recoverable free phase oil and dissolved phase contaminants in
the off-site area across the bayou. All three of the current extraction-well arrays pump from the
Shallow Artesian Aquifer. Figure 1-1 shows the locations of the three current extraction-well arrays.
2.3 TREATMENT SYSTEM
The pump-and-treat system treats the extracted groundwater, sand filter backwash water, and
stormwater that collects inside the treatment system containment area. Treated water is then discharged
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to the bayou. The treatment system removes free-phase and dissolved-phase creosote to below
established discharge limits.
The system is designed to operate at up to 50 gpm. The average pumping rate from the extraction
system is around 15 gpm. The treatment plant operates in a batch mode, treating groundwater and
free phase oil at 25 gpm.
Major components of the treatment system include an oil/water separator, filter-feed tank, sand filtration
vessels, oleophilic-media filter, granular activated carbon vessels, backwash tank, recovered oil tank, post
aeration tank, stormwater sump, air compressors, air dryer system, and air blower.
The treatment system operates in the following manner:
• the extracted groundwater and free phase oil enter the oil/water separator at 16 gpm;
• the recovered oil is stored in a recovery tank and is then disposed off site;
• the water from the oil/water separator discharges to the filter feed tank; and
• in a semi-batch mode, the water in the filter feed tank is pumped at about 25 gpm through the
sand filters, oleophilic-media filter, carbon vessels, post aeration tank, and then to the
Western Drainage Channel.
2.4 MONITORING SYSTEM
The monitoring program consists of measuring water levels in 10 monitoring wells and sampling of site
contaminants in four of the 44 extraction wells. The water levels are measured daily to ensure
drawdown does not fall below -4 feet MSL. Of the 10 monitoring wells used for this purpose five are
located onsite in various locations and five are located offsite near Array 3. Sampling for site
contaminants in the four extraction wells is to determine the concentrations of contaminants in the
extracted groundwater.
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3.0 SYSTEM OBJECTIVES, PERFORMANCE AND CLOSURE
CRITERIA
3. 1 CURRENT SYSTEM OBJECTIVES AND CLOSURE CRITERIA
The goal of the remediation action, as documented in the ROD, is to
• reduce or eliminate the potential for ingestion of carcinogens in groundwater, surface soils,
and in the food chain;
• control the migration of PAH contamination in the Shallow Artesian Aquifer and other
aquifers; and
• reduce or eliminate the direct contact threat posed by bayou sediments and onsite surficial
creosote wastes.
The initial source control action of dredging and excavation primarily addressed the first and last
objectives while the current pump-and-treat system is designed to address the first and second
objectives. The objectives targeted by the pump-and-treat system could be achieved through
containment and/or cleanup of the creosote. The site managers recognize the preference of
Superfund for permanent solutions and primarily focus on removing as much free product as possible
(although one of the extraction well arrays designed to recovery NAPL primarily operates to control
dissolved contamination). It is likely, however, that some NAPL will remain in the subsurface as a
continuing source of dissolved phase contamination.
The ROD also mentions that 3.1 ng/L is the drinking water standard for PAHs (unclear if this is for
total or individual PAHs) but mentions the groundwater treatment system is, in essence, a pilot study
and only will reach a cleanup level that is technically feasible. The target level, however, will be
based on the 1O4 or 1O6 level (presumably cancer risk). The ROD also notes that Bayou Bonfouca
falls under the Resource Conservation and Recovery Act (RCRA) and therefore monitoring must
continue for 30 years after system shutdown to ensure adequate closure of the site.
3.2 TREATMENT PLANT OPERATION GOALS
The current contract for operations calls for the plant to operate 24 hours per day, seven days a week
while treating water from all designated active extraction wells. A plant operator and a maintenance
person attend the facility 44 hours per week including visits on weekends and holidays.
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3.3
ACTION LEVELS
The ROD states that remedial actions must attain legally applicable or relevant and appropriate
Federal and state standards. The effluent or discharge levels reflected by these standards are
provided in Table 3-1 for a sample of the contaminants of concern noted at Bayou Bonfouca.
Table 3-1. Required discharge levels for the groundwater treatment system.
Contaminant
TOC
Oil and Grease
TSS
Acenapthene
Anthracene
Benzo(a)anthracene
Chrysene
Fluoranthene
Fluorene
Napthalene
Phenanthrene
Pyrene
2,4 Dimethylphenol
Arsenic
Effluent Levels
35mg/L
15mg/L
45mg/L
47ppb
47ppb
47ppb
47ppb
54ppb
47ppb
47ppb
47ppb
48ppb
47ppb
0.05 mg/L
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4.0 FINDINGS AND OBSERVATIONS FROM THE RSE SITE VISIT
4.1 FINDINGS
The RSE team found a smoothly running treatment system and an extremely well-operated and
maintained site. The Performance Evaluation Report for Shallow Artesian Aquifer Remediation
conducted in 1997 provided a thorough review of the site and resulted in tremendous improvements in
the system effectiveness. 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
The extraction system operates smoothly with infrequent shutdowns. Installation of the new
controllerless pumps have eliminated the problems previously encountered with the controllers of the
original pumps. Occasional freezing during the winter, and extremely low recharge levels cause
pumping to be reduced temporarily or shut down. While the extraction rates for each of the arrays
can be determined automatically with flow meters, the pumping rates and oil recovery of individual
extraction wells cannot be determined automatically. Rather each well may be monitored manually
by discharging the pump into a bucket and observing volume of water and oil.
The operator compiles monthly operational reports from monitoring data. These reports include
detailed charts on the pumping status for each of the extraction wells, monthly and cumulative
volumes of extracted water and oil, groundwater elevations, and laboratory results from water quality
sampling.
4.2.1 WATER LEVELS
The contractors have rigorously monitored and controlled drawdown levels near the extraction well
arrays to minimize the effect of subsidence on the onsite landfill or private pads adjacent to the site.
A minimum groundwater elevation of -4 feet MSL is allowed, and this limit is based on experience of
long-term pumping at the site. Pumping at maximum capacity would exceed this level; therefore, only
a portion of the wells in each array are pumped at a given time. For example, often odd pumps are
run on one day and even pumps are run on the next day. In addition to this cycling, individual pump
rates are controlled by adjusting air exhaust rates. Pumping may be shut down or significantly
reduced during low periods of rainfall.
4.2.2 CAPTURE ZONES
While monitoring water levels for subsidence is routinely conducted, monitoring to ensure containment
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of the contaminants of concern is not. During the Performance Evaluation in 1997, simulated
potentiometric surfaces were created for a range of conditions using limited available data and
modeling. There are no monitoring well clusters placed between known areas of contamination and
the bayou; thus, containment of the freephase creosote and dissolved PAHs is not confirmed.
Consequently, the operator has no knowledge as to the groundwater levels that must be achieved in
order to maintain containment and capture of the plumes.
4.2.3 CONTAMINANT LEVELS
Extraction wells 2-18 through 2-23 are good producers of oil for Array 2. The remaining wells in this
array are meant to prevent contaminant migration to the Eastern Drainage Channel. Since the
addition of the two new extraction well Arrays (la and 3) in 2000, oil production has doubled. This is
attributed to Array 3, in which all wells are good producers of oil. Array la produces almost no oil as
expected and is meant to prevent flow of dissolved contamination to the bayou.
Groundwater is only sampled for contaminants from four of the extraction wells and the inlet to the oil
water separator. This allows the operator to tabulate recovered contaminants but does not provide
information about the extent of the contamination, including whether or not contaminants exist beyond
the capture zones of the extraction-well arrays and are migrating toward the drainage channels or the
bayou. Furthermore, since the original Remedial Investigation, the bayou water and sediments have
not been sampled as part of site activities for PAHs or oil and grease. The State of Louisiana
conducts sampling in the bayou, but these data have not been easily accessible to site managers and
therefore were not reviewed by the RSE team. Thus, it could not be determined if the bayou is
contaminated (with freephase or dissolved product), and if it is, whether the contamination results
from current migration from contaminated portions of the subsurface or from residual product left in
the bayou after dredging.
4.3 COMPONENT PERFORMANCE
A Performance Evaluation Report for Shallow Artesian Aquifer Remediation was developed and
finalized in September 1997. This report thoroughly evaluated the system and its performance. It
made several recommendations to enhance operation of the system as well as methods to improve
site restoration. These Phase 2 changes were completed in September 2000. The treatment system
is simply and effectively designed. The main operator-labor functions are well pump cycling and
manual sand filter backwashes (the filters are designed to allow automatic backwashes) and site
upkeep. While similar systems are operated with 20 or less hours of attention, the subsidence issue
and excellent site maintenance needed and achieved at this location require more time.
The system has effectively met effluent goals reducing total BNA (Base Neutral/Acid extractable
organics, which includes the PAHs of concern) levels from 6602 ug/L (prior to the sand filter) to 23.6
ug/L in the December 2000 sample. The arsenic effluent limit of 50 ug/L has also been met with the
system reducing influent concentrations of 114 ug/L to non-detect levels in December 2000. Iron
concentrations at the site are above commonly used standards. There is no current discharge
standard set for iron at this site, but a chelating agent is used to sequester it and prevent coloration of
the plant discharge.
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4.3.1 WELLS AND PUMPS
The location of extract!on-well Arrays la, 2, and 3 are shown in Figure 1-1. The recovery wells are
not monitored individually to determine the quantity of oil recovered. They are, however, periodically
checked, and the plant operator has found that Arrays 2 and 3 are recovering free product and Array
la is not recovering free product.
4.3.1.1 ARRAY!
The Array 2 extraction well network was installed in 1991 and has operated continuously since that
time. Array 2 extraction pumps were replaced (1999) in order to maintain the operation and reliability
of the network over the life of the remediation effort.
The selected pump was a CEE AutoPump Model AP-4/BL Short, which is a submersible air-
displacement, controllerless, bottom-loading pump that
• requires a regulated source of compressed air,
• self-adjusts the discharge flow rate automatically to match the well yield,
• uses air only when discharging fluid,
• pumps particles up to 1/8 inch in diameter,
• can operate on contaminated air, and
• can pass 90-weight gear oil without fouling the air valve.
Replacement of the pumps in Array 2 began in September 1999. Redevelopment of each well to
remove fine sand that had accumulated in the wells was completed as part of the process of pump
replacement. New air regulators, check valves, and exhaust needle valves were also installed with
the new pumps. Five of the wells were overdrilled and reinstalled. The remaining structures, piping,
vaults, and valving associated with each of the Array 2 wells were not replaced.
4.3.1.2 ARRAY IA
Array la extraction well network is located adjacent to the existing landfill and consists of 12
extraction wells aligned along the southern and western perimeters of the landfill. The Array la wells
were drilled and completed in March 2000. These wells were completed in the Shallow Artesian
Aquifer. The CEE Model AP-4/BL pumps were installed in Array la.
The new extraction wells associated with Array la were completed below grade in aluminum vaults
with locking covers. The construction of wells below existing grade may lead to occasional inundation
from sheet flow runoff. The design of the extraction well vaults included a sump and check valve
that allows water accumulation in the well vault to flow into the well. Since the extraction wells
continually remove fluid, the water is evacuated to the GWTS. The vaults were completed
approximately one inch above grade to minimize the infiltration of surface water.
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4.3.1.3 ARRAYS
The Array 3 extraction network is located on private property in the Chamale Cove Subdivision on the
western shore of Bayou Bonfouca and consists often extraction wells manifolded together in a north-
south alignment. The Array 3 wells were drilled and completed in March 2000. These new
extraction wells were completed in the Shallow Artesian Aquifer and include the CEE Model
AP4/BL pumps. Five additional monitoring wells were installed in the Array 3 area. The purpose of
the new monitoring wells was to provide continuous measurement of groundwater levels in support of
the subsidence monitoring program. Each monitoring well contains a level transducer to measure
water level. The signal is transmitted to the data logger and computer located at the groundwater
treatment plant.
The Array 3 well vaults are similar to the Array la vaults.
4.3.1.4 SUBSIDENCE
Each monitoring well contains a level indicator that is electronically transmitted to the control system.
The control point is set to maintain groundwater elevation at or above -4 feet MSL. The set point of
-4 feet MSL is somewhat arbitrary.
4.3.2 Am COMPRESSORS
Two rotary screw air compressors are used to supply air to extraction well pumps, the pneumatic control
valves, and filter air scour. These compressors are water cooled using treated groundwater for the
primary heat transfer fluid. Water exiting the carbon vessels is passed through the compressors for
cooling. In the event that process water can not adequately cool the compressors, city water is
introduced as makeup to-maintain a constant flow rate of 14.5 gpm to the compressors.
Excessive quantities of city water were used prior to increasing the quantity of water being recovered
in the three Arrays. The new pumps have increased the quantity of recovered water; thereby
reducing the need for make up city water.
4.3.3 OIL/WATER SEPARATOR
Extracted groundwater and free phase creosote is pumped to the oil/water separator from the extraction
wells. The influent passes through a surge column to reduce the velocity surges characteristic of
pneumatic well pumps so that the flow can be accurately metered. Creosote settles in the oil /water
separator hopper, where it is manually pumped on a monthly basis to the recovered oil tank. The
oil/water separator is equipped with a floating oil skimmer, but the skimmed oil tank has been removed
due to a lack of oil to be skimmed. The collected oil is disposed of at a TSD facility. The system
currently operates at about 15 gpm.
Oil is still recovered in significant quantities; therefore, this unit is still vital to plant operations. This
unit has been evaluated recently and is functional.
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4.3.4 FILTER FEED TANK
Oil/water separator effluent flows by gravity into the sand filter feed tank. This tank serves as a holding
basin to supply the filter feed pumps. The tank is equipped with a level controller to monitor fluid inlet
and outlet flow rates. The system currently is run in semi-batch mode at a flow rate set by the operator.
The current flowrate through the system is about 25 gpm.
4.3.5 SAND FILTERS
From the filter feed tank influent is pumped through one of two sand filter vessels. Only one filter is on
line at a time, except during a switch over. These filters remove residual oil and suspended solids that
are not removed in the oil/water separator. The sand filter units can be air scoured and backwashed.
These operations are fully automated, with the backwash sequence being initiated by a high differential
pressure across the filter beds (indicating a fouled filter), by a timer sequence (initially set at once per
day), or by manual initiation. Current practice is to manually initiate a backwash three times per week
(Monday, Wednesday and Friday).
4.3.6 OLEOPHILIC FILTER
The oleophilic filter media removes residual oil that may pass through the sand filter. The primary
purpose of this unit operation is to protect the carbon filters. This filter can be manually backwashed,
but no set backwash schedule or criteria have been followed. The filter has not been backwashed
and the nonexistent differential of TOC in the influent and effluent of this filter suggest it has been
fouled.
The media is scheduled for replacement by USAGE and IT Group prior to turnover of the plant to the
State of Louisiana. Sampling of the media for effectiveness, potentially with total organic carbon
(TOC) measurements, should continue.
4.3.7 GRANULAR ACTIVATED CARBON UNITS
Four granular activated carbon (GAC) vessels (each containing 3,000 pounds) are provided to remove
dissolved-phase creosote compounds from the water leaving the oleophilic filter. The GAC vessels can
be operated in series or in parallel. Currently, the water travels through three of the vessels in series.
Each GAC vessel can be manually backwashed. Backwashing of the GAC vessels removes accumulated
solids and biological growth that may decrease the flow rate through the vessels. Effluent from the GAC
vessels is routed to a once through cooling system for the air compressors. When the effluent water flow
rate is too low to provide adequate cooling to the air compressor, city water is introduced automatically
to the cooling water stream. The carbon was replaced in December 1999. Prior to this, the operator
estimated that GAC replacement has only been necessary every 3 years. The next scheduled
replacement is scheduled to take place before the system is turned over to the State of Louisiana in July
2001.
4.3.8 POST AERATION TANK
After passing through the air compressor cooling coils, the GAC effluent is discharged to the post
aeration tank. A blower supplies low-pressure air through a coarse air diffuser to aerate the effluent
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before discharge. Effluent overflows to the bayou through a gravity discharge line. The post-aeration
tank also provides a source of water for backwashing filter vessels. Prior to backwashing, aeration
for the post-aeration tank can be discontinued in order to minimize air entrainment and backwash
pump cavitation.
4.3.9 BACKWASH TANK
The backwash tank is used to contain the water resulting from backwashing any of the filter vessels.
Backwash water stored in this tank is metered into the treatment process upstream of the oil/water
separator with the backwash solids pumps. Metering of backwash water can be done manually or
through an automatic procedure. As mentioned earlier, it is currently done manually on Mondays,
Wednesdays, and Fridays.
4.3.10 RECOVERED AND SKIMMED OIL TANK
The recovered oil tank is used to store "heavy" oil recovered in the oil/water separator. It is equipped
with outlets in the tank side wall to allow for removal of water floating on the oil and disposal of a
recovered product with a high oil-to-water ratio. On a periodic basis (two to three times per year),
the tank is emptied into a tank truck for offsite disposal.
4.3.11 STORMWATER SUMP
The stormwater sump is used primarily for the collection and containment of rainwater until conditions
allow for the treatment of this water through the treatment system. In addition, this sump also receives
treatment area spills and tank cleanouts and overflows. The stormwater sump pump can be operated
either in manual or automatic mode. Automatic mode operates the sump pump by level within the
stormwater sump. Manual operation disables the level control. Operation of the sump pump is typically
in the automatic mode.
4.3.12 TOTAL ORGANIC CARBON (TOC) SAMPLER
The performance of the groundwater treatment plant is currently monitored on a monthly basis by
collecting samples from various points within the treatment process and testing them with a Shimadzu
TOC-4000 . Samples are currently collected from the sand filter inlet, oleophilic filter inlet, GAC filter
inlet, GAC 80% throughput point, and GAC effluent. The purpose of the TOC monitoring system is
to expand the number of sample points, provide automatic on-site testing, and to monitor the
groundwater treatment plant performance. The plant operator changes carbon vessels when the
TOC at the 80% throughput point measures 76 mg/L (the discharge criteria is 35 mg/L) although no
clear guideline was ever instituted. Given that the influent to the carbon units is approximately 35
mg/L, the 76 mg/L action limit will likely never occur.
The automated TOC analysis system includes a sample collection system, a sample manifold box, an
automated combustion infrared TOC analyzer, and a spent sample collection and disposal system. The
resulting TOC data is recorded and logged in the new data acquisition computer that is also used for the
subsidence monitoring program. The analyzer calibrates itself with standards every 40th sample.
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4.3.13 Am DRYER SYSTEM
All air that exits the compressors is dried using a dual column, regenerative air dryer, designed to
prevent the accumulation of condensation in the air lines and pneumatic valves.
4.3.14 Am BLOWER
The air blower delivers air to the post-aeration tank to raise the dissolved oxygen content of the effluent
before discharge to the bayou. The amount of air going to the post-aeration tank can be valved to supply
more or less air, depending on specific aeration needs.
4.3.15 SEQUESTERING/CHELATING AGENT
In order to minimize iron fouling of the treatment system and reduce coloration of the discharge, a
chelating agent is added to the ground-water. A metering pump and associated tankage is located at
the end of Array 2. The chelating agent is metered into the influent line to the system. By injecting at
the end of Array 2, the agent has plenty of residence time to ensure proper mixing prior to entering
any unit operations.
4.4 COMPONENTS OR PROCESSES THAT ACCOUNT FOR MAJORITY OF
COSTS
The State of Louisiana is currently preparing a package for bid for the operation and maintenance of
this facility; therefore, costs will only be discussed in general terms. Monthly costs are approximately
$30,000 to $35,000 (i.e., annual costs of approximately $400,000).
4.4.1 UTILITIES
The current utilities to operate the plant should remain approximately the same for the foreseeable
future. By maintaining higher volumes of recovered groundwater, the need for city water should be
diminished. Average utility costs are approximately $3,000 per month ($36,000 per year).
4.4.2 NON-UTILITY CONSUMABLES AND DISPOSAL COSTS
Disposal of recovered oils costs approximately $22,600 annually, and carbon costs approximately
$11,500 annually.
4.4.3 LABOR
The plant is currently staffed by a plant operator and maintenance technician (44 hours per week
each). Both staff members work Monday through Friday and visually check the system on Saturday
and Sunday. Additional project management costs are also incurred.
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4.4.4 CHEMICAL ANALYSIS
Chemical analysis is currently only conducted on four recovery wells and not at any of the monitoring
wells. The analytical costs for these four samples is approximately $900 per month.
4.4.5 OTHER COSTS
Over $3 million has been spent on upgrading and operating the plant and expanding the extraction
system in accordance with the 1997 report recommendations. Upgrades themselves cost
approximately $1 million to $1.5 million and have increased plant operations costs and also made the
system much more protective.
4.5 RECURRING PROBLEMS OR ISSUES
The upgrade in plant equipment as discussed above has remedied most recurring problems.
4.6 REGULATORY COMPLIANCE
The treatment plant does not exceed the regulatory criteria for treatment and disposal.
4.7 TREATMENT PROCESS EXCURSIONS AND UPSETS, ACCIDENTAL
CONTAMINANT/REAGENT RELEASES
Based on information made available to the team, there have been no controlled releases of
contaminated water within the facility during operation of the plant. The only mention of a
contaminant release referred to an offsite spill by an unknown party in which an unknown constituent
traveled through one of the drainage channels or the creek to the bayou. Within a few weeks, the
observable effects of the spill had abated.
4.8 SAFETY RECORD
The plant appears to have had 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
PAH concentrations are only measured in four of the extraction wells; therefore, PAH concentrations
in the groundwater are relatively unknown. While the Remedial Investigation noted that there was no
contamination of the Deep Artesian Aquifer, PAH concentrations of this formation have not been
measured since that initial investigation.
Groundwater from the contaminated Shallow Artesian Aquifer is not used for public consumption
near the site. According to the ROD, with the exception of one offsite well at a depth of 100 feet, the
seven existing wells sampled during the Remedial Investigation were between 1,000 and 2,300 feet
deep. These wells were not contaminated with PAHs and are expected to be unaffected by the site
contamination. Thus, the only avenue of human exposure to site related PAHs is through surface
water of the drainage channels and the bayou, which receives water from both the surficial deposits
and the Shallow Artesian Aquifer. However, the current sampling program cannot indicate if
contaminated groundwater is discharging to the surface water.
5.2 SURFACE WATER
Surface water in the area consists of the bayou and the Western and Eastern Drainage Channels.
Sampling of the bayou water and sediments is conducted by the State of Louisiana. This sampling is
not part of the site activities and is not provided to the site managers for analysis. It is possible that
PAHs may currently discharge into the bayou via the groundwater of the Shallow Artesian Aquifer or
via the Western Drainage Channel where pockets of PAH contamination were found in the surficial
deposits during the Remedial Investigation.
Surface water presents the only current likely human exposure to the site-related PAHs. Two
avenues are of particular interest. The first is the use of the bayou for fishing or swimming. The
plant operator indicated that people fish there on a regular basis and likely eat what they catch.
People were observed on the bulkhead fishing in the bayou near the entrance of the Eastern Drainage
Channel the first day of RSE visit. In addition, a "no swimming" advisory is posted on the State
website (http://www.deq.state.la.us/surveillance/mercury/fishadvi.htm). but no signs regarding the
advisory are posted near the site. The second avenue of possible exposure is through a constructed
wetland on the Perkins property along the western boundary of the bayou. This constructed wetland
pumps water from the bayou when conditions are dry. No sheen or other visual evidence of
contamination was present in this constructed wetland during the RSE visit.
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5.3 AIR
Air is an unlikely exposure avenue of PAHs at the site.
5.4 SOILS
The surface contamination identified in the ROD have been removed under previous operable units.
5.5 WETLANDS AND SEDIMENTS
Contaminated sediments in the wetlands surrounding the bayou and the creek to the east of the site
were previously excavated. Drain slots are cut into the sheet-pile bulkhead walls every 200 to 300
feet to allow intertidal flow to the existing wetland.
Excavation of the bayou sediments extended to the depth where the interpolated concentration of
PAHs was 1,300 ppm. The degree of contamination below this line of interpolation is unknown;
however, uncontaminated crushed limestone was backfilled into the bayou to cover the remaining
contaminated sediments and to restore the bayou to its original depth. The effect of PAHs on the
wetlands in the Western Drainage Channel are unknown as pockets of contamination were found in
the surficial deposits along two portions of the channel. These pockets were found during the
Remedial Investigation, were not addressed by the source control, and have not been sampled since
that initial investigation.
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6.0 RECOMMENDATIONS
The Bayou Bonfouca Superfund Site is anticipated to be turned over to the State of Louisiana on July
11, 2001. At the time of the RSE visit, the Louisiana Department of Environmental Quality was
preparing the announcement for bids to operate the plant. As a result, cost and cost savings are
estimated by the RSE team for the purpose of this report.
The role of the EPA after site turnover was not clearly ascertained during the site visit. The EPA
role should be made clear to the site RPM, state regulator, and site contractor before turnover.
6.1 RECOMMENDED STUDIES TO ENSURE EFFECTIVENESS
6.1.1 DELINEATE PLUME AND EVALUATE CAPTURE ZONE OF EXTRAC TION WELL ARRAYS
The plume extent and the capture zones of the extraction-well arrays have not accurately been
determined. Due to the large extent of NAPL and dissolved phase contamination and the proximity to
residences to the west of the bayou, plume delineation may be difficult or impossible. In addition, due
to tidal fluctuations and the temporal variation in pumping, the capture zone may be difficult to
determine. However, controlling the migration of site-related contaminants in the Shallow Artesian
Aquifer and other aquifers is an objective of the ROD, and this control cannot be adequately
evaluated without delineation of the contaminant plumes and evaluation of capture provided by the
extraction system.
Analysis of the 10 water-level measurements collected for monitoring associated with subsidence
control and water-level measurements from other site-related sampling points including the bayou
itself would improve the understanding groundwater flow both on and offsite. These measurements
could also be used to update the groundwater flow model created as part of the 1997 Performance
Evaluation Report.
In addition, sampling of site-related contaminants at multiple sampling points should be used to help
delineate portions of the plume and evaluate plume capture. Although these sampling results will not
determine the capture zone, trends in contaminant concentrations may help determine if capture is
adequate. The 1997 Performance Evaluation Report (Sections 2.4.2 and 6.4.3.2) suggested semi-
annual sampling of site-related contaminants in wells F-2, G-2, OW-1B, 1-12, 1-18, C-2, N, and 2-1.
The RSE team concurs with this recommendation as many of these wells are well placed for
evaluating capture. However, the 2000 System Modifications Report, which documents the
implementation of changes recommended by the 1997 Performance Evaluation Report, shows that
many if not all of these have been abandoned due to degraded well vaults.
To evaluate capture associated with Arrays la and 2, the RSE team recommends installing five new
monitoring wells that screen the Shallow Artesian Aquifer. Water levels should be measured in these
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new wells, and samples should be collected from these new wells semi-annually and analyzed for
BNAs. The following locations are suggested (see Figure 1-1 for these recommended locations):
• near the location of abandoned well G-2;
• near the location of abandoned well OW-3B;
• near the location of abandoned well OW-1B;
• approximately 200 feet due east of extraction well 1A-8 (i.e., up to 50 feet east of the edge of
the estimated dissolved phase plume);
• and downgradient of abandoned well C-2.
Water levels from these wells should be compared to those from the bayou and the extraction wells.
For adequate capture provided by Array la and portions of Array 2, these water levels should
indicate flow toward the extraction wells and away from the bayou. In addition, for adequate capture
provided by Array la and portions of Array 2, samples from these wells should indicate consistently
decreasing or undetectable concentrations of site-related contaminants. As mentioned in the 1997
Performance Evaluation Report, if NAPL is found in a sample, the volume of NAPL should be
recorded and compared to previous findings and lab analysis is not required.
If the locations of these wells are within the site boundaries, installation costs should be approximately
$5,000 per well for a total capital cost of $25,000, and analytical costs associated with sampling five
wells twice per year should be less than $6,000 per year.
It should be noted that the recommendation adjustments to the monitoring program will not completely
delineate the plume or assure capture by Arrays la and 2. This program would, however, provide a
strong indicator if capture is not provided. Furthermore, this recommended monitoring program does
not address the offsite NAPL plume. As this offsite plume is not fully delineated and capture offered
by the Array-3 wells has not been analyzed, the remedy is potentially inconsistent with the ROD
objective requiring control of migration of PAH contamination Shallow Artesian Aquifer and other
aquifers.
6.1.2 SAMPLING OF SURFACE-WATER, SEDIMENT, BENTHICS, AND FISH
The bayou and drainage channels provide the most likely avenues of human exposure to PAHs and
other contaminants of concern. Sampling of the bayou water and sediments is conducted by the State
of Louisiana, but analysis of this sampling is not part of site activities. Given the use of these waters
for public fishing and possible consumption of these fish, a comprehensive analysis of the surface
water, sediments, fish, and benthics should be conducted. In addition, the results of this analysis
should be used to evaluate the effectiveness of the current pump-and-treat remedy.
EPA Region 6 stated that efforts are currently being planned in coordination with EPA Headquarters
to evaluate the effectiveness of the source removal actions conducted in the bayou prior to operation
of the pump-and-treat system. While this evaluation would provide a "snap shot" of the extent (if
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any) of site-related contamination in the bayou, it would not provide the trend in contamination (if any)
that would help indicate the effectiveness of the pump-and-treat system of protecting the bayou from
migration of subsurface contamination (i.e., over time increasing or steady but significant contaminant
concentrations may indicate subsurface migration of contaminants into the bayou).
As a result, it is recommended that the site managers review on an annual basis the sampling
conducted by the State of Louisiana. Furthermore, if the State sampling program does not provide
sufficient information to evaluate the effectiveness of the pump-and-treat system to protect the bayou
from migrating subsurface contamination, additional sampling and analysis may be required as part of
the site activities. This is especially important given the use of the bayou for fishing and the possible
consumption of those fish.
Finally, in visiting the State of Louisiana website, the RSE team identified a "no swimming" advisory
for Bayou Bonfouca; however, no signs indicating this advisory were posted along the bayou near the
site. The RSE team recommends such signs be posted.
6.2 RECOMMENDED CHANGES TO REDUCE COSTS
6.2.1 ELIMINATE SAMPLING PROGRAM OF CURRENT EXTRACTION WELLS
The quantitative monthly sampling of contaminants from the four extraction wells provides little or no
information regarding the extent of the plume or the progress of cleanup beyond the sample of the
composite system influent. Therefore, sampling of these wells can be eliminated to reduce costs
without further compromising effectiveness. Sampling from the additional monitoring wells mentioned
in Recommendation 6.1.3 will provide the necessary information regarding the extent of
contamination. Eliminating this monthly sampling of the four extraction wells would save
approximately $900 per month or $10,800 per year in analytical costs.
6.2.2 REINVESTIGATE RECYCLING OF COLLECTED CREOSOTE
The plant operator mentioned that he had investigated potential receptors of the collected creosote.
This should be reinvestigated. The collected creosote is likely still useable and can be recycled.
Obstacles may include meeting product specifications of potentially accepting facilitiesand/or
reluctance to take material from a Superfund site. However, the option should nevertheless be
pursued to see if the obstacles can be overcome. Indemnification of the facility that takes the
material or incentives may help avoid these obstacles. This would reduce the cost of disposal which
is estimated at $22,600 annually.
6.3 MODIFICATIONS INTENDED FOR TECHNICAL IMPROVEMENT
6.3.1 PERIODIC CHECKS AND REPORTING OF NAPL RECOVERY IN INDIVIDUAL WELLS
The plant operator already conducts qualitative periodic checks of the NAPL recovered from each of
the wells. Making these checks quantitative and less frequently would demonstrate the performance
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of each extraction well over time. At the time of the RSE all extraction wells were cycled on and off
at various times. Identifying the extraction wells that produced the most NAPL would help the site
managers determine which wells should run continually and which wells can be cycled on and off
without sacrificing NAPL recovery. NAPL recovery by pumping from select wells, however, should
not be increased if capture is compromised.
6.3.2 MONTHLY EVALUATION OF DAT A
Monthly reports are prepared that compile the pumping logs, water and oil recovery, subsidence
monitoring, and monthly sampling. Including a short summary of the data that highlights significant
parameters would facilitate the reviewing of these reports by EPA and State managers. In addition,
writing these summaries may help the operator and/or contractor identify any anomalies or trends in
the system operation or performance.
6.3.3 CLARIFY ROLE OF TOC MEASUREMENTS FOR CARBON CHANGE Our
A Shimadzu TOC-4000 automatically provides TOC measurements at the inlets to the sand filters,
oleophilic filter, and primary carbon as well as 80% of the distance through the primary carbon and
the effluent. The differential between the last two measurements are used to determine when carbon
change out should occur. TOC at the first three measurement points are typically around 35 mg/L
and the fourth and fifth are typically near 0 mg/L. The plant operator mentioned he would change the
carbon vessels when the fourth measurement reads 76 mg/L. Given that the influent is well below
this action level, the carbon will never be switched. This action level should be revisited.
6.3.4 INVESTIGATE INCREASED EXTRACTION RATES
Extraction rates for the three extraction arrays are controlled to maintain groundwater elevation at or
above -4 feet MSL to minimize subsidence in the area. During the RSE visit, the site managers
indicated that this control level (-4 feet MSL) is somewhat arbitrary. Because this control level
reduces the extraction rates below the capacity of the system, it is recommended that the a more
relaxed control level be investigated. This can be achieved by conducting consolidation tests of the
subsurface soils to determine how much the effective stress can be increased before damaging
consolidation occurs. An approximate cost for conducting and interpreting such tests is $30,000. This
analysis will include an evaluation as to whether or not oil recovery rates would likely increase with
additional pumping. If higher extraction rates could be accomplished without creating subsidence
problems, the recovery of NAPL would increase thereby potentially reducing the duration of the
current system.
6.4 MODIFICATIONS INTENDED TO GAIN SITE CLOSE-OUT
6.4.1 ESTABLISH EXIT STRATEGY AND CLOSURE CRITERIA
There is no clear exit strategy. The main objectives of the pump-and-treat system are to control the
migration of PAH contamination in the Shallow Artesian Aquifer and other aquifers and reduce or
eliminate the potential for ingestion of carcinogens in groundwater, surface soils, and shellfish. The
ROD recognizes the Clean Water Act levels of 3.1 ng/L for PAHs in drinking water but states, "The
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technical feasibility of cleaning the groundwater to this level is unknown. The groundwater treatment
system currently envisioned will extract and treat to the extent technologically practicable". Thus,
there is no clear point at which the pump-and-treat system can be shutdown. Without such a pre-
determined point, operation may continue long beyond the point of diminishing returns. As such, a
clear exit strategy should be developed. This strategy should demonstrate protection of human and
ecological health based on data including that obtained from the recommended sampling program that
includes surface water, sediment, and additional monitoring wells (Recommendations 6.1.1 and 6.1.2).
After continual operation of the current pump-and-treat system, alternative remediation strategies
may provide improved protection of human and ecological health at a reduced cost. The performance
of the pump-and-treat system and the availability of such strategies should be evaluated on a regular
basis to determine the most appropriate time for shutdown of the current system.
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7.0 SUMMARY
In general, the RSE team found a smoothly running treatment system and an extremely well-operated
and maintained site. The Performance Evaluation Report for Shallow Artesian Aquifer Remedation
conducted in 1997 provided a thorough review of the site and resulted in tremendous improvements in
the system effectiveness. The observations and recommendations mentioned 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 have the obvious
benefit of the operational data unavailable to the original designers.
Several recommendations are made to assure system effectiveness, reduce future operations and
maintenance costs, improve technical operation, and gain site close out. The recommendations to
improve effectiveness include an improving the sampling program to help delineate the plume,
evaluate the capture zone of the current extraction well arrays, and determine if surface water and
sediments have harmful PAH concentrations. The recommendations for cost reduction include
potentially recycling the recovered creosote to eliminate disposal costs, and eliminating laboratory
analysis of samples taken monthly from the extraction wells. The recommendations for technical
improvement include determining which extraction wells are the most productive NAPL producers,
analyzing and summarizing data in the monthly reports, clarifying the role of total organic carbon
(TOC) measurements, and investigating potentially higher extraction rates. Finally, development of a
clear exit strategy that ensures protection of human and ecological that is based on the new sampling
program is advised.
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Table 7-1. Cost Summary Table
Recommendation
Delineate plume and
evaluate capture zone
Review results from current
State and future EPA
sampling of surface water
and sediments
Eliminate analysis of
samples from four
extraction wells
Recycle Creosote
Sample each extraction well
forNAPL (no lab analysis)
Monthly Evaluation of
Data
Clarify role of TOC samples
Investigate effect of higher
extraction rates on
subsidence
Develop exit strategy
Reason
Effectiveness
Effectiveness
Cost
reduction
Cost
reduction
Technical
improvement
Technical
improvement
Technical
improvement
Technical
improvement
Gain close out
Estimated Change in
Capital
Costs
$25,000
$0
$0
$0
$0
$0
$0
$30,000
$50,000
Annual
Costs
$6,000
$500
($10,800)
($22,600)
$0
$2,000
$0
$0
$0
Lifecycle
Costs*
$205,000
$15,000
($324,000)
($678,000)
$0
$60,000
$0
$30,000
$50,000
Lifecycle
Costs**
$122,000
$8,000
($174,000)
($365,000)
$0
$32,000
$0
$30,000
$50,000
Costs in parentheses imply cost reductions.
* assumes 30 years of operation with a discount rate of 0% (i.e.,
** assumes 30 years of operation with a discount rate of 5% and
no discounting)
no discounting in the first year
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FIGURES
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FIGURE 1-1. SITE LAYOUT SHOWING AREAS OF CONTAMINATION AND EXTRACTION WELL LOCATIONS.
WEST HALL AVENUE
LEGEND
RECOMMENDED MONITORING
WELL LOCATION
EXTRACTION WELL
INTERPRETED AREAL EXTENT OF
FREE PHASE AND DISSOLVED
PHASE CREOSOTE PLUME IN
THE SURFICIAL WATER BEARING
ZONE
INTERPRETED AREAL EXTENT OF
FREE CREOSOTE PLUME IN THE
SHALLOW ARTESIAN AQUIFER
INTERPRETED AREAL EXTENT OF
DISSOLVED PHASE CREOSOTE IN
THE SHALLOW ARTESIAN AQUIFER
300
SCALE IN FEET
600
NOTE: This figure is based on Figure 2-1 la from the 1997 Performance Evaluation Report for Shallow Artesian Aquifer
Restoration, CH2M Hill, Inc. and Sheet reference number AB-G4 from the 2000 Ground-water Extraction Wells and
Ground-water Treatment System Modifications (Phase 2), Bayou Bonfouca Superfund Site. IT Corporation. The estimated
extent and location of the free creosote plume from Figure 2-11 a have been adjusted to be consistent with findings that no
free creosote was found during installation of Array 1 a.
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FIGURE 1-2. PROFILE OF BAYOU AND STRATIGRAPHY.
(Taken from Performance Evaluation Report for Shallow Artesian Aquifer Restoration,
Prepared for Bayou Bonfouca Superfund Site, September 1997, CH2M Hill, Inc.)
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Solid Waste and
Emergency Response
(5102G)
542-R-02-008f
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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