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
NOTICE

Work described herein was performed by GeoTrans, Inc. (GeoTrans) and the United States Army Corps

of Engineers (USACE) 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. 
i

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 and1970. 

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
ii

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.
iii

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

(USACE 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
iv

The project team is grateful for the help provided by the following EPA Project Liaisons.

Region1 

Region 2

Region 3

Region 4

Region 5

Darryl Luce and Larry Brill

Diana Cutt

Kathy Davies

Kay Wischkaemper

Dion Novak

Region 6

Region 7

Region 8

Region 9

Region 10

Vincent Malott

Mary Peterson 

Armando Saenz and Richard Muza

Herb Levine

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).
v

TABLE OF CONTENTS

EXECUTIVE SUMMARY ........................................................................ i

PREFACE ........................................................................................ iii

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 1A ........................................................ 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
vi

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 NAPLRECOVERY 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
1

1.0 INTRODUCTION

1.1 PURPOSE

In the OSWER Directive No. 9200.0-33, Transmittal of Final FY00 - 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 (USACE), using a process called a Remediation System

Evaluation (RSE), which was developed by USACE. 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.
2

1.2 TEAM COMPOSITION

The team conducting the RSE consisted of the following individuals:

Frank Bales, Chemical Engineer, USACE, 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 Date Title/Description

US EPA 3/31/1987 Record of Decision, Bayou Bonfouca Superfund Site,

Slidell, LA, March 31, 1987

US EPA 2/5/1990 Explanation of Significant Differences

USACE, Kansas City

District

9/1990 Section 01810 Groundwater Operation and

Maintenance

M.C. Anthon Waterwell

Contractor

1990 Well installation logs. Well no 2-1 through 2-23

M.C. Anthon Waterwell

Contractor

1990 Well installation logs. Well no SM-1 through SM-9

US EPA 7/20/1995 Amendment to the Record of Decision, Bayou

Bonfouca Superfund Site, Slidell, LA, July 1995

US EPA 9/1996 Groundwater Remedial Action, Five-Year Review,

Bayou Bonfouca Superfund Site, Slidell, LA

CH2M Hill 9/29/1997 Response Action Contract, US EPA Regioin 6,

Performance Evaluation Report for Shallow Artesian

Aquifer Remediation

US EPA 9/30/1997 Preliminary Close Out Report, Bayou Bonfouca

Superfund Site, Slidell, LA

USACE, Tulsa and

New Orleans Districts

12/1999 95% Design Submittal, Groundwater Extraction Wells

and Groundwater Treatment System Modifications

(Phase 2), Bayou Bonfouca Superfund Site, Slidell,

Louisiana

IT Corporation 12/2000 Bayou Bonfouca Groundwater Remediation Monthly

Operational Report, November 1, 2000 through

November 30, 2000
3

IT Corporation 12/2000 Groundwater Extraction Wells and Groundwater

Treatment System Modifications (Phase 2), Bayou

Bonfouca Superfund Site, Slidell, LA, Draft Final

Report

IT Corporation 1/2001 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, USACE, New Orleans District

Jim Montegut, Project Engineer, USACE 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 SITE LOCATION, HISTORY, AND CHARACTERISTICS

1.5.1 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
4

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 of free 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. 
5

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 1a, 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 1a, 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
6

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.
7

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 10-4 or 10-6 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. 
8

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 Effluent Levels

TOC 35 mg/L

Oil and Grease 15 mg/L

TSS 45 mg/L

Acenapthene 47 ppb

Anthracene 47 ppb

Benzo(a)anthracene 47 ppb

Chrysene 47 ppb

Fluoranthene 54 ppb

Fluorene 47 ppb

Napthalene 47 ppb

Phenanthrene 47 ppb

Pyrene 48 ppb

2,4 Dimethylphenol 47 ppb

Arsenic 0.05 mg/L
9

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
10

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 (1a and 3) in 2000, oil production has doubled. This is

attributed to Array 3, in which all wells are good producers of oil. Array 1a 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.
11

4.3.1 WELLS AND PUMPS

The location of extraction-well Arrays 1a, 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

1a is not recovering free product.

4.3.1.1 ARRAY 2

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 airdisplacement, 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 1A

Array 1a 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 1a 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 1a.

The new extraction wells associated with Array 1a 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.
12

4.3.1.3 ARRAY 3

The Array 3 extraction network is located on private property in the Chamale Cove Subdivision on the

western shore of Bayou Bonfouca and consists of ten extraction wells manifolded together in a northsouth 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 1a 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 AIR 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 USACE 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
14

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.
15

4.3.13 AIR 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 AIR 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 groundwater. 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.
16

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.
18

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.
19

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 EXTRACTION 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 semiannual 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 1a and 2, the RSE team recommends installing five new

monitoring wells that screen the Shallow Artesian Aquifer. Water levels should be measured in these
20

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 1a 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 1a 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 1a 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
21

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
22

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 DATA

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 OUT

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
23

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 predetermined 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.
24

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.
25

Table 7-1. Cost Summary Table

Recommendation Reason

Estimated Change in

Capital

Costs 

 Annual

Costs

 Lifecycle

Costs*

Lifecycle

Costs**

Delineate plume and

evaluate capture zone

Effectiveness $25,000 $6,000 $205,000 $122,000

Review results from current

State and future EPA

sampling of surface water

and sediments

Effectiveness $0 $500 $15,000 $8,000

Eliminate analysis of

samples from four

extraction wells

Cost

reduction

$0 ($10,800) ($324,000) ($174,000)

Recycle Creosote Cost

reduction

$0 ($22,600) ($678,000) ($365,000)

Sample each extraction well

for NAPL (no lab analysis)

Technical

improvement

$0 $0 $0 $0

Monthly Evaluation of

Data

Technical

improvement

$0 $2,000 $60,000 $32,000

Clarify role of TOC samples Technical

improvement

$0 $0 $0 $0

Investigate effect of higher

extraction rates on

subsidence

Technical

improvement

$30,000 $0 $30,000 $30,000

Develop exit strategy Gain close out $50,000 $0 $50,000 $50,000

Costs in parentheses imply cost reductions.

* assumes 30 years of operation with a discount rate of 0% (i.e., no discounting)

** assumes 30 years of operation with a discount rate of 5% and no discounting in the first year
FIGURES
NOTE: This figure is based on Figure 2-11a from the 1997 Performance Evaluation Report for Shallow Artesian Aquifer

Restoration, CH2M Hill, Inc. and Sheet reference number AB-G4 from the 2000 Groundwater Extraction Wells andGroundwater Treatment System Modifications (Phase 2), Bayou Bonfouca Superfund Site, IT Corporation. The estimatedextent and location of the free creosote plume from Figure 2-11a have been adjusted to be consistent with findings that no

free creosote was found during installation of Array 1a.
25

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.)
U.S. EPA National Service Center 

for Environmental PublicationsP.O. Box 42419Cincinnati, OH 45242-2419

Solid Waste and Emergency Response(5102G)

542-Octowwwwww