REMEDIATION SYSTEM EVALUATION
MACGILLIS & GIBBS SUPERFUND SITE
NEW BRIGHTON, MINNESOTA
Report of the Remediation System Evaluation,
Site Visit Conducted at the MacGillis & Gibbs Site
13-14 June, 2000
Final Report Submitted to Region 5
February 26, 2001
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NOTICE
Work described herein was performed by GeoTrans, Inc. (GeoTrans) and the United States Army Corps
of Engineers (USAGE) for the U.S. Environmental Protection Agency (U.S. EPA). Work conducted by
GeoTrans, including preparation of this report, was performed under Dynamac Contract No. 68-C-99-
256, Subcontract No. 91517. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
This document (EPA 542-R-02-008c) 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The site was a wood preserving facility that is no longer active. Key contaminants at the site include
pentachlorophenol (PCP), chromium, and to a much lesser extent dioxin, arsenic, and polynuclear
aromatic hydrocarbons (PAHs). Both light non-aqueous phase liquids (LNAPL) and dense non-
aqueous phase liquids (DNAPL) represent continuing sources of dissolved PCP groundwater
contamination. The site is underlain by a sequence of glacial sands and tills. The uppermost unit is
the New Brighton Formation, which consists of sand and clayey silt. The remediation system
addresses the New Brighton aquifer.
USEPA has divided the site into three Operable Units:
OU1: Contaminated soil/debris in a former disposal area, plus some soils from OU3 that
have been mixed with OU1 soils, plus removal of below-ground tanks, vaults, and
pipes from OU3
OU2: LNAPL in the former PCP process area, plus above-ground process tanks
OU3: All other contaminated soils and groundwater
This RSE only pertains to the ongoing groundwater remediation of OU2 (a small LNAPL recovery
system) and OU3 (a groundwater pump-and-treat system located both on-site and off-site).
The RSE suggests several potential modifications to address effectiveness issues, including:
development and regular update of a target capture zone for PCP and chromium
regular evaluation of actual capture with respect to the target capture zone
formalizing and implementing a long-term monitoring plan for the New Brighton
aquifer and the underlying Hillside Aquifer
improving fencing and/or security and request that Williams Brothers secure a
pipeline that runs through the site
evaluating a proposed new building that will potentially overly LNAPL and/or
DNAPL, with respect to potential exposures and/or impacts to the OU2 extraction
well
The RSE also suggests several potential modifications to reduce long-term costs, including:
elimination of the OU2 treatment system by merging it with the OU3 system now
that the larger OU3 system is fully operational (potential net savings of
approximately $0.5M over the remaining 4 years of expected operation for the OU2
system, non-discounted)
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elimination the bioreactor from the OU3 treatment system if it is determined (via
pilot test) that organo-clay and/or GAC can more cost-effectively treat the water,
given that PCP influent concentrations are now significantly lower than original
design influent concentrations (potential net savings of more than $1.5M over 30
years, non-discounted)
elimination of select discharge monitoring points (potential net savings of nearly
$1M over 30 years, non-discounted)
The RSE also suggests consideration of an alternate strategy where higher discharge limits are
potentially negotiated with the POTW, eliminating the need for pretreatment altogether. The RSE
also suggests several other potential modifications intended for technical improvement.
Estimated capital and annual costs (and savings) associated with recommendations are summarized in
a table at the end of the report.
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PREFACE
This report was prepared within the context of a demonstration project conducted by the United
States Environmental Protection Agency's (USEPA) Technology Innovation Office (TIO). The
objective of the overall project is to demonstrate the application of optimization techniques to Pump-
and-Treat (P&T) systems at Superfund sites that are "Fund-lead" (i.e., financed by USEPA). The
demonstration project was conducted in USEPA Regions 4 and 5.
The demonstration project has been carried out as a cooperative effort by the following organizations:
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
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
The project team is grateful for the help provided by an EPA Project Liaison in each Region. Kay
Wischkaemper in Region 4 and Dion Novak in Region 5 were vital to the successful interaction
between the project team and the Regional Project Managers (RPM's) during the course of this
project, and both actively participated in one Remediation System Evaluation (RSE) site visit
conducted in their Region.
The data collection phase of this project included interviews with many RPM's in EPA Regions 4 and
5. The project could not have been successfully performed without the participation of these
individuals.
Finally, for the sites where RSE's were preformed, additional participation and substantial support
was provided by the RPM's (Ken Mallary and Ralph Howard in Region 4; Steve Padovani and
Darryl Owens in Region 5), and their efforts are very much appreciated, as are the efforts of the State
regulators and EPA contractors who also participated in the RSE site visits.
in
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TABLE OF CONTENTS
EXECUTIVE SUMMARY i
PREFACE iii
TABLE OF CONTENTS iv
1.0 INTRODUCTION 1
1.1 PURPOSE 1
1.2 TEAM COMPOSITION 1
1.3 DOCUMENTS REVIEWED 2
1.4 PERSONS CONTACTED 3
1.5 SITE LOCATION, HISTORY, AND CHARACTERISTICS 3
1.5.1 LOCATION 3
1.5.2 POTENTIAL SOURCES 4
1.5.3 HYDROGEOLOGIC SETTING 4
1.5.4 DESCRIPTION OF GROUND WATER PLUME 5
2.0 SYSTEM DESCRIPTION 6
2.1 SYSTEM OVERVIEW 6
2.2 EXTRACTION SYSTEM 6
2.3 TREATMENT SYSTEM 8
3.0 SYSTEM OBJECTIVES, PERFORMANCE AND CLOSURE CRITERIA 11
3.1 CURRENT SYSTEM OBJECTIVES AND CLOSURE CRITERIA 11
3.2 TREATMENT PLANT OPERATION GOALS 12
4.0 FINDINGS AND OBSERVATIONS FROM THE RSE SITE VISIT 13
4.1 FINDINGS 13
4.2 SUBSURFACE PERFORMANCE AND RESPONSE 13
4.2.1 WATERLEVELS 13
4.2.2 CAPTURE ZONES 13
4.2.3 CONTAMINANT LEVELS 13
4.3 TREATMENT SYSTEM DOWN-TIME 13
4.4 COMPONENTS OR PROCESSES THAT ACCOUNT FOR MAJORITY OF COSTS 13
4.4.1 UTILITIES (OU3 ONLY, DETAIL FOR OU2 NOT PROVIDED) 14
4.4.2 NON-UTILITY CONSUMABLES AND DISPOSAL (OU3) 14
4.4.3 LABOR(OU3) 14
4.4.4 SAMPLING AND ANALYSIS (OU3) 15
4.4.5 OTHER COSTS (OU3) 15
4.4.6 SUMMARY OF TOTAL COSTS 15
4.5 RECURRING PROBLEMS OR ISSUES 15
4.5.1 BAG FILTERS 15
4.5.2 PRODUCT RECOVERY, OU2 16
4.5.3 PIPING CLOGGING 16
4.5.4 RADIO CONTROLLERS AND WELL CYCLING 16
4.5.5 BlOFOULING AT WELLS 16
4.5.6 HEAT EXCHANGER 16
4.5.7 TREATMENT SYSTEM FLOW RATE 16
4.5.8 EW8 16
4.6 REGULATORY COMPLIANCE 17
iv
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4.7 TREATMENT PROCESS EXCURSIONS AND UPSETS, ACCIDENTAL CONTAMINANT/REAGENT
RELEASES 17
4.8 SAFETY RECORD 17
5.0 EFFECTIVENESS OF THE SYSTEM TO PROTECT HUMAN HEALTH AND THE ENVIRONMENT
18
5.1 GROUND WATER 18
5.2 SURFACE WATER 18
5.3 AIR 18
5.4 SOILS 18
5.5 OTHER 18
6.0 RECOMMENDATIONS 19
6.1 RECOMMENDED STUDIES TO IMPROVE EFFECTIVENESS 19
6.1.1 DEVELOP/UPDATE TARGET CONTAINMENT ZONE 19
6.1.2 CAPTURE ZONE ANALYSIS 19
6.1.3 LONG-TERM MONITORING 19
6.1.4 FENCING/SECURITY AND EXPOSED PIPELINE 19
6.1.5 DONATELLE EXPANSION 20
6.1.6 ATMOSPHERIC DISCHARGE FROM THE WATER TREATMENT PLANT 20
6.2 RECOMMENDED CHANGES TO REDUCE COSTS 20
6.2.1 SHUTDOWN OU2 SYSTEM 20
6.2.2 CONSIDER MODIFYING OU3 TREATMENT (ELIMINATE BIOREACTOR) 20
6.2.3 REDUCE SAMPLED DISCHARGE POINTS 21
6.3 MODIFICATIONS INTENDED FOR TECHNICAL IMPROVEMENT 21
7.0 SUMMARY 22
List of Tables
Table 7-1. Cost summary table
List of Figures
Figure 1 -1. Site layout and groundwater high near pond.
v
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1.0 INTRODUCTION
1.1 PURPOSE
The US Environmental Protection Agency's (USEPA) Technology Innovation Office (TIO) and the
US Army Corps of Engineers (USAGE) Hazardous, Toxic, and Radioactive Waste Center of
Expertise (HTRW CX) are cooperating in the demonstration of the USAGE Remediation System
Evaluation process at Superfund sites. The demonstration of the RSE's is 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, such as the MODMAN code.
The MacGillis & Gibbs site was chosen based on initial screening of pump and treat systems
managed by USEPA Region 5 and represented a site with relatively high operation cost and a long
projected operating life. One or two sites in Regions 4 and 5 will be evaluated with RSE's in the first
phase of this demonstration project. A report on the overall results from these demonstration sites
will also be prepared and will identify lessons learned, typical costs savings, and a process for
screening sites in the USEPA regions for potential optimization savings.
The RSE process is meant to identify cost savings through changes in operation and technology, to
evaluate performance and effectiveness (as required under the NCP, i.e., and "five-year" review),
assure clear and realistic remediation goals and exit strategy, and verify adequate maintenance of
Government owned equipment. 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.
1.2 TEAM COMPOSITION
The team conducting the RSE included:
Kathy Yager, HQ EPA TIO
Peter Rich, Engineer, HSI GeoTrans (EPA TIO's contractor)
Rob Greenwald, Hydrogeologist, HSI GeoTrans (EPA TIO's contractor)
Bill Crawford, Chemical Engineer, USAGE HTRW CX
Dave Becker, Geologist, USAGE HTRW CX
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1.3 DOCUMENTS REVIEWED
The following documents were reviewed as part of the RSE evaluation:
Author
EPA
Ecology & Environment
Ecology & Environment
EPA
Carbonair
BioTrol
Black & Veatch
Black & Veatch
Black & Veatch
Black & Veatch
Black & Veatch
Black & Veatch
Black & Veatch
Black & Veatch
Ecology & Environment
EPA
Black & Veatch
August Mack
Ecology & Environment
Ecology & Environment
Conestoga Rovers
Date
9/30/91
7/16/93
2/2/94
9/22/94
11/10/97
11/11/97
??
5/98
11/98
11/98 and
12/98
2/99
Varies, 1999
Varies, 1999
Varies, 1999
and 2000
Varies, 1999
and 2000
9/30/99
4/1/00
4/26/00
5/1 8/00
??
6/1 9/00
Title/Description
ROD, OU2
Feasibility Study, OU3
Pre-Design Study, OU2
ROD, OU3
O&M Manual, OU2
O&M Manual, BioTrol Aqeuous Treatment System, OU2
Figures A-1 through A-10 (plume maps based on data from
1995, 1996, and 1997)
OU3 Pre-Remedial Design Groundwater Modeling Report
Figures J, K, and L (draft plume maps based on September
1998 GeoProbe sampling)
Simulated potentiometric surface maps for actual extraction
scenarios (i.e., actual locations and design rates)
Subcontract Documents, Volume 1 of 2 (Bidding
Documents), OU3
Subcontract Documents, Volume 1 of 2 (Bidding
Documents), OU3
Subcontract Documents, Volume 2 of 2 (Bidding
Documents), OU3
Monthly/Quarterly Status Reports, OU3
Monthly Technical Status Reports, OU2
ROD Amendment, OU1 and OU3
Figures M, N, and O (Plume maps based on sampling
round 1a in February 1999, and sampling round 1B in
December 1999)
Industrial Waste Discharge Report
Dip Tank 2 Investigation and Product Removal
Troubleshooting, OU2
Evaluation of EW-1 OU-2
Quarterly Report, Bell Lumber
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1.4 PERSONS CONTACTED
The following individuals were present during the site visit:
Darryl Owens, EPA RPM, Region V
Nile Fellows, Minnesota Pollution Control Agency (MPCA)
Fred Campbell, MPCA
Dan Card, MPCA
Larry Campbell, Project Manager, Black & Veatch, Chicago
Rob Blake, Black & Veatch, Kansas City
Ben Horenziak, P.E., Ecology & Environment
Matt Alleva, Carbonair Environmental Systems
1.5 SITE LOCATION, HISTORY, AND CHARACTERISTICS
This RSE pertains to OU2 and OU3 at MacGillis & Gibbs ("MacGillis", also referred to as "the
site"). MacGillis is listed on the NPL along with Bell Lumber & Pole (Bell), an adjacent property.
Bell is being remediated separately by a PRP, while MacGillis is being remediated by USEPA. Only
the MacGillis site is addressed in this RSE.
MacGillis was a wood preserving facility that is no longer active. USEPA has divided the site into
three Operable Units:
OU1: Contaminated soil/debris in a former disposal area, plus some soils from OU3 that
have been mixed with OU1 soils, plus removal of below-ground tanks, vaults, and
pipes from OU3
OU2: LNAPL in the former PCP process area, plus above-ground process tanks
OU3: All other contaminated soils and groundwater
Figure 1-1 illustrates the location of OU1 and the recovery well for OU2. The remaining area is
OU3. This RSE only pertains to the ongoing groundwater remediation of OU2 (a small LNAPL
recovery system) and OU3 (a groundwater pump-and-treat system located both on-site and off-site).
1.5.1 LOCATION
The site is located in a mixed residential and commercial area in New Brighton, Minnesota. The site
is located in Ramsey County, and is approximately 30 minutes north of Minneapolis.
The site is generally flat, with scattered debris over much of the site. The site is not fenced, and has
open access. All original process buildings and tanks have been removed. There are two separate
buildings that house groundwater treatment plants (one for OU2 and one for OU3), located adjacent
to each other on the eastern side of the site. There is a pond within the geographic boundary of OU1,
on the western side of the site. An exposed Williams Brothers gasoline pipeline was observed
running within the pond. A rail yard is located adjacent to the site on the west. The sole extraction
well associated with ongoing OU2 activity is located in the northern part of the site, on a large
concrete pad. An office building (Donatelle) is located immediately adjacent of the site to the north.
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Some extraction wells associated with OU3 remediation are located on-site, and others are located
off-site to the east, northeast, and west (see Figure 1-1).
1.5.2 POTENTIAL SOURCES
Materials used for wood preserving included PCP, creosote, and chromated copper arsenate (CCA).
An initial environmental investigation occurred in 1979, after a spill of 4000-5000 gallons of CCA.
OU1 on the western part of the site was a disposal area for the facility (a topographic depression filled
with scrap post and poles, wood chips, solids, spent PCP solutions, etc.). Outside of OU1, there were
two significant process areas (see Figure 1-1): 1) the PCP process area; and 2) the chromated copper
arsenate (CCA) area. Other areas of the site were used for storage of treated and untreated lumber.
In the 1960's a change was made in PCP processing from a PCP/Proviline 4-A mixture to a PCP/P-9
oil mixture. This was significant because the new mixture was less dense than water, whereas the
previous mixture was more dense than water. The new mixture required significantly more process
wastewater, which was likely disposed of in the pond in OU1. Note that significant LNAPL is still
observed on-site in the PCP process area (i.e., EW-8, EW-9, and the OU2 extraction well), and this is
likely from the new mixture. The presence of DNAPLs from the old mixture, in the vicinity of the
OU1 pond (MW3B, MW8B, MW5B) and far from the OU1 pond (MW19B, WP-5) is also
considered likely based on groundwater concentrations in basal wells plus DNAPL observations in
borings. Both LNAPL and DNAPL represent continuing sources of dissolved PCP groundwater
contamination.
Metal-contaminated soils associated with the CCA process area was remediated in July 1997,
primarily through excavation activities.
1.5.3 HYDROGEOLOGIC SETTING
The site is underlain by a sequence of glacial sands and tills. The uppermost unit is the New Brighton
Formation, which consists of sand and clayey silt. The New Brighton ranges in thickness from 14 to
71 feet. Depth to water varies from 5 to 20 feet. The New Brighton is underlain by the Twin Cities
till, an aquitard that is approximately 25 to 60 feet thick. The underlying aquifer is the Hillside Sand
Formation.
The New Brighton receives recharge from precipitation. The New Brighton aquifer is limited in areal
extent beyond the site (it extends 0.5 miles west, 0.75 miles east, 2 miles north, and 2 miles south of
the site). A series of lakes, streams, and wetlands exist primarily where the aquifer pinches out, and
these are interpreted as points of groundwater discharge. Due primarily to these factors, groundwater
within the New Brighton flows radially from a potentiometric high located in the vicinity of OU1
pond (see Figure 1-1). Since OU1 was a historical source of groundwater impacts, those impacts are
observed in all directions off-site due to the radial flow pattern. With respect to the PCP and CCA
process areas, predominant groundwater flow is to the northeast towards Parrel's Lake. The
hydraulic conductivity is approximately 10"2 to 10"3 cm/sec, and groundwater flow velocity is on the
order of 0.2 ft/day to 1.0 ft/day (100 to 350 ft/yr).
The Hillside Aquifer is confined, with flow to the north. Hydraulic conductivity is estimated at 10"3
cm/sec.
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1.5.4 DESCRIPTION OF GROUND WATER PLUME
The remediation system that is the focus of this RSE is limited to the New Brighton aquifer.
Contaminants in the New Brighton include PCP, chromium, arsenic, dioxin, and carcinogenic PAH's.
As previously mentioned, DNAPL and LNAPL associated with PCP are found in OU1 as well as
specific locations throughout the PCP process area. The operating OU2 system addresses an area of
LNAPL located near the northern site boundary. It was essentially an interim system intended to
prevent further off-site migration of this LNAPL and associated groundwater contamination. LNAPL
thickness of up to 6.5 ft are observed at the extraction well and piezometers located nearby.
However, no LNAPL is observed in the two downgradient piezometers (PZ-7 and PZ-8). LNAPL is
also observed on-site at EW-8 and in the monitor wells near MW-9.
As discussed above, the past occurrence of a ground water divide under the site and the locations of
various processes at this large site has resulted in several dissolved contaminant plumes extending
from the site. PCP is most widespread and PCP plumes, defined by a 1 ug/L contour, extend
approximately 2000 feet east-northeast and 2100 feet west-northwest of the source areas. A separate
Bell PCP plume extends southwest from the Bell property. Another recently discovered PCP plume
extends westward from an area between Bell and MacGillis and Gibbs property. Concentrations of
PCP exceed 1,000 ug/L in these plumes. The plume extending west-northwest from the MacGillis
and Gibbs site has an anomalous hot spot (over 10,000 ug/L) near extraction well EW-13.
Concentrations between this hot spot and the MacGillis and Gibbs property are significantly lower.
The cause of these high concentrations is not known. A chromium plume extends 1,200 feet east-
northeastward from the CCA treatment area and two arsenic plumes extend northward from CCA
area and southward from the southern border of the MacGillis and Gibbs property. The southern
arsenic plume is not well defined and only based on two sampling points.
PCP strongly sorbs onto soils, and thus migrates very slowly with respect to groundwater velocity.
Other PAHs and dioxins are extremely immobile in a dissolved form given their affinity for sorption
to soils. The mobility of these contaminants is much higher in the presence of mobile NAPL. The
mobility of arsenic and chromium is strongly dependent on the oxidation/reduction conditions in the
aquifer and the nature of the contaminant salt. Arsenic is more mobile under reducing conditions and
chromium is much less mobile under reducing conditions.
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2.0 SYSTEM DESCRIPTION
2.1 SYSTEM OVERVIEW
The remediation system consists of two operating systems:
OU2 - 1 extraction well on-site in an area with LNAPL, expected to operate for 4 more years
OU3 - 13 extraction wells (12 active) in areas of dissolved contamination located both on-
site and off-site
The treatment system for each operable unit is very similar, and consists of an oil/water separator, a
bioreactor, a filter system, and GAC. The OU2 system was an interim system, and the full-scale
system (OU3) required a new treatment plant with significantly larger capacity.
The purpose of the bioreactor is primarily to reduce concentrations of PCP. Water is discharged from
the treatment plant to the sanitary sewer. For OU3, some of the off-site wells discharge directly to the
sanitary sewer without treatment. Furthermore, water from several additional OU3 wells is diverted
directly to the treatment plant effluent holding tank for discharge to the sewer, without treatment.
Water from one additional OU3 well is only treated with GAC (no biotreatment). Details of the
extraction and treatment systems are provided below.
2.2 EXTRACTION SYSTEM
The OU2 extraction well ("OU2 EW-1") has a Clean Environment pneumatic total fluids submersible
pump that maintains a drawdown at the pump level. The well is operated with a four foot drawdown,
which is interpreted to provide a capture zone that prevents product migration offsite to the northeast.
There is a bladder pump intended for automated collection of LNAPL, but the automation has never
worked well and instead LNAPL is manually collected from the extraction well and nearby
piezometers. This well went on-line in December 1997, with full operation in March 1998. To date,
approximately 134 gallons of LNAPL have been removed, and it is estimated that 128 of the 134
gallons have been removed via hand-bailing (ROD originally estimated oil removal of 10 gal/day, but
that has not occurred). The treatment plant for OU2 was designed for 10 gpm, and originally 4 gpm
was achieved. After the OU3 system was installed, however, production dropped at the OU2 well to
approximately 1 gpm.
OU3 has 13 existing wells (12 active), plus 1 planned well, as follows:
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OU3
Well
EW-1*
EW-3
EW-4
EW-5
EW-7
EW-8
EW-9
EW-10
EW-11
EW-1 2
EW-1 3
EW-1 4
EW-1 5
EW-1 6
Status
Active
Planned
Active
Active
Active
Not Active
Active
Active
Active
Active
Active
Active
Active
Active
Destination of Water
To plant effluent tank,
direct discharge to sewer
Will go to sewer once
access for well is gained
Direct discharge to sewer
To plant, treatment with
GAG only
To plant effluent tank,
direct discharge to sewer
LNAPL periodically
removed (peristaltic
pump)
Treatment in plant
Treatment in plant
Treatment in plant
Direct discharge to sewer
Treatment in plant
Direct discharge to sewer
Direct discharge to sewer
Direct discharge to sewer
Design
Rate(gpm)
7.0
35.0
10.0
7.0
6.0
10.0
5.0
15.0
10.0
7.0
12.0
5.0
10.0
5.0
Avg.
1999(gpm)
2.2
-
6.4
4.7
2.0
-
7.5
15.2
6.6
8.1
9.5
0.5
1.7
5.6
Avg
2000(gpm)
4.0
-
5.0
6.0
3.4
-
5.5
20.6
14.8
5.4
12.7
0.1
0.9
2.9
* EW-1 in OU3 is not the same well as "OU2 EW-1"
EW-2 and EW-6, located east/northeast of the site, were not installed (MNA planned in that area)
The OU3 system went online in March 1999. EW-3, located northeast of the site, has not yet been
completed due to access restrictions. EW-8, located on-site in the PCP process area, has significant
LNAPL (up to 20-25 ft has been observed), and this well is not actively treated to avoid harm to the
biomass in the bioreactor. Extraction wells EW3 and EW15 are configured to pump either to the
water treatment plant or to the sewer, based on contaminant concentrations.
The OU3 wells are typically 8-inch diameter stainless steel (SS) wells with three 2-inch diameter SS
rehab wells located five feet from the extraction well to treat fouling. The extraction wells are all
screened in the surficial New Brighton aquifer The OU3 extraction wells have electric submersible
pumps with high and low level controls. The onsite wells are operated to dewater the pond induced
groundwater mound area and prevent further impacted groundwater migration offsite. The offsite
wells are operated to provide a capture zone for groundwater with PCP over 50 to 100 |ig/L and
chromium over the MCL of 100 |ig/L. The wells are completed below grade with a pitless adaptor
and a flow control valve nearby. The well discharge lines are led back to the treatment system
individually with flow meters prior to the system influent tank. Power for the offsite wells is taken
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via metered lines from nearby utility poles and the well pumps are controlled by radio from the
treatment plant.
2.3 TREATMENT SYSTEM
The OU2 and OU3 treatment systems are quite similar. The OU2 system was an interim system, and
the full-scale system (OU3) required a new treatment plant with significantly larger capacity. Details
of each system are highlighted below, followed by a listing of significant differences between the
OU2 and OU3 treatment systems.
The OU2 treatment system, designed for 10 gpm, consists of the following:
HDPE (contained in PVC) transfer pipe from the lone extraction well;
A 50 gpm oil/water separator (Carbonair COW50);
A bioreactor system (approximately 7500 gallon capacity Biotrol 4K3) with appurtenant
preheater and nutrient and caustic addition;
A settling tank;
Four bag filters (FSI);
Two 1500-pound liquid phase granular activated carbon (GAC) units (Carbonair PC 13-100
gpm capacity); and
One 2000-pound vapor phase GAC unit (Carbonair GPC-20).
The OU2 system was designed for a flow rate of 10 gpm at PCP levels up to 100 mg/L when
operation was initiated. The actual flow rate is currently approximately 1 gpm, with influent PCP
level of 10 to 25 mg/L. The flow rate has decreased from a reported volume of 4 gpm since the OU3
system was started in March 1999. Chromium in the 100 mg/1 range can poison the microbes in the
bioreactor, but current chromium concentrations in the OU2 extraction well (approximately 50 ug/1)
are not negatively impacting the bioreactor.
The OU3 treatment system, designed for 50 gpm, consists of the following:
Radio controlled electric submersible pumps;
HDPE piping to the treatment system;
A 3300 gallon influent holding tank;
A 50 gpm oil/water separator (Carbonair COW50);
A bioreactor system (approximately 14,000 gallon capacity Biotrol 12K4) with appurtenant
boiler and nutrient addition;
A flash floe and clarifier system ((Model IPC Great Lakes Environmental);
A 2500 gallon filter feedtank;
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Ten 5-micron bag filters (Krystil Klear);
Two 5000-pound liquid phase GAC units (Carbonair PC28-200 gpm capacity);
A 3300 gallon effluent holding tank;
A 10-65 cubic foot Model 50 Waterlink - Lanco filter press; and
One 2000-pound vapor phase GAC units (Carbonair GPC-20R).
The OU3 system was designed for a flow rate of 50 gpm and an influent PCP concentration of 10
mg/L. The system operates near its design flow rate and slightly below its design influent
concentration.
Extraction wells are routed to the OU3 treatment system based on PCP concentration. Offsite wells
with levels less than 3 mg/L are discharged directly to the sewer at nearby manholes. In addition to
PCP levels, onsite wells have the potential for dioxin levels which require GAC treatment (although
onsite well EW-11 had been discharged directly to the sewer prior to January 5, 2000).
In each system, the phase separator is designed to remove a portion of the suspended solids and the
light and dense non-aqueous phase liquids from the influent groundwater stream. The free product
phase (LNAPL) is collected in a 55 gal drum which is disposed of off-site at a RCRA permitted
facility. The suspended solids and DNAPL phase (if any) are removed together and disposed of off
site at a RCRA approved facility. The operator has the option of sending sludge (if not contaminated
with DNAPL) from the phase separator to the sludge tank. The water phase is pumped through a heat
exchanger where the temperature is raised to 70°F prior to entering the fixed film Bioreactor (note
that the heat exchanger for OU2 is not operated because it has been empirically determined to not be
necessary). A natural gas fired boiler installed outside the building supplies the hot water to preheat
the water fed to the bioreactor.
The bioreactor in each system is designed to remove dissolved phase organic compounds, in this case
mainly PCP, by microbial action. Nutrients and air are added in both systems, and the pH is
controlled (in OU2 only, via chemical addition) to promote the growth of these microorganisms. The
water flows through the bioreactor and collects in the discharge chamber. A blower collects vapors
from the influent tank, phase separator, bioreactor, and sludge tank for treatment in a vapor phase
activated carbon vessel prior to discharge to the atmosphere.
For OU3, water is pumped from the bioreactor discharge chamber to the flash/floe tank and clarifier
system to remove biological and suspended solids. Polymer is added to the flash/floe tank to promote
coagulation of these particles. For OU2, water goes directly to the clarifier (sodium hydroxide is
added to increase pH). In the OU3 system, the sludge collects in the bottom of the clarifier and is
pumped to the sludge tank. Sludge is then pumped to the plate and frame filter press. Water from the
filter press is recycled to the water treatment plant influent tank. The sludge, which is collected in 55
gal drums, is classified as F032 waste and is shipped off-site to RCRA treatment, storage and
disposal facilities. For the OU2 system, the sludge is accumulated in the bottom of the clarifier. For
each system, loading on floe tanks/clarifiers is very low, and thus very hard to run. Therefore, very
little sludge is generated. The OU3 filter press has only been used once in a year of operation and the
OU2 clarifier has not required sludge removal in two years of operation.
In each system, water is pumped through the bag filters and granular activated carbon vessels to the
effluent holding tank. The bag filters operate in parallel and remove residual biological sediment
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carried over from the clarifier system. The bag filters require frequent changing ( as much as 1-2
times per day in OU3, which adds up to 200 or more filter bags per month) because the clarifier does
not effectively removed sloughed biomass from the bioreactor.
The two liquid phase carbon units are operated in series and adsorb dioxins and other residual
dissolved organics prior to discharge to the effluent holding tank. The effluent tank water provides
flow and process control and blends extracted water from other wells as needed. The effluent water is
sampled, flow and pH are monitored and displayed prior to final discharge to the POTW sanitary
sewer system lift station.
Carbon usage in each system is extremely minimal, and has never been changed out in either system
(liquid or vapor phase). However, the lead liquid-phase carbon vessel in OU3 is being backwashed
twice a week to prevent pressure drop due to biofouling.
Plant air is supplied by an air compressor located in the building. The compressor is used to supply
air to the filter press and sludge pumps.
The building also contains a sump to collect clean up water and for spill control. There are two sump
pumps which can either discharge to the influent tank for recycle through the treatment plant or
discharge directly to the sewer.
Significant differences between the OU2 and OU3 treatment systems are as follows:
The OU2 system was designed for 10 gpm (actually treating 1 gpm), the OU3 system was
designed for 50 gpm (actually treating close to 50 gpm)
The feed water to the bioreactor in the OU2 system is not heated, while the water in the OU3
system is heated
The OU2 system influent is a slurry of LNAPL and water, while the OU3 system influent
does not generally handle any LNAPL
The OU2 requires caustic addition to adjust the pH, while the OU3 system operates in the
6.8-7.6 pH range without adjustment
The OU3 system has a sludge-handling dewatering system, while in the OU2 system sludge
is accumulated for eventual removal/disposal.
10
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3.0 SYSTEM OBJECTIVES, PERFORMANCE AND CLOSURE
CRITERIA
3.1 CURRENT SYSTEM OBJECTIVES AND CLOSURE CRITERIA
The OU2 ROD indicates that the goal of the OU2 system is to lower the aquifer in the vicinity of the
extraction well, to draw LNAPL towards the extraction well. Therefore, the goal of the OU2 system
is to contain LNAPL movement as well as to remove LNAPL. There is no stated closure criteria for
the OU2 system.
The OU3 ROD indicates the goal is to remediate groundwater to the following concentrations:
PCP: 1 ug/1
chromium: 100 ug/1
carcinogenic PAH's: 0.2 ug/1
arsenic: 5 ug/1
dioxin: 12 picograms/liter
In practice, the OU3 system is being managed to contain the 50 to 100 ug/1 PCP plume, and/or the
100 ug/1 chromium plume.
The ROD also states that groundwater contamination may be persistent, and that contingency
measures and objectives may have to be implemented. The contingency measures might include:
groundwater containment (gradient control)
waiving chemical-specific ARARs based on technical impracticability or inability to achieve
further contaminant reduction
institutional controls to restrict aquifer access
The ROD states that performance will be monitored, and that modifications may include any or all of
the following:
discontinued pumping at individual wells where cleanup goals have been attained
alternating pumping wells to eliminate stagnation points
pulse pumping to allow adsorbed contaminants to dissolve
install additional wells
remedial technologies to enhance removal of DNAPL
However, a formal groundwater monitoring plan has yet to be implemented.
11
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3.2 TREATMENT PLANT OPERATION GOALS
This is a continuously operating system. It is manned periodically during the week (less than 15
hrs/wk for OU2 and approximately 30 hrs/wk for OU3). The plant operates automatically over the
weekend. Groundwater is extracted from wells for treatment and/or direct discharge to the POTW
sanitary sewer system. Effluent water discharged to this sewer must meet Metropolitan Council
Environmental Services (MCES) discharge requirements included in the MCES Permit. These limits
include the following:
any individual organic: 3,000 ug/1
total organics: 10,000 ug/1
dioxin: < 0.002 ug/1
chromium: 8,000 ug/1
copper: 6,000 ug/1
arsenic: 4,000 ug/1
pH: 5 to 11
COD: 500 mg/1
TSS: 250 mg/1
CN 4000 ug/1
Pb 1000 ug/1
Hg 100 ug/1
Ni 6000 ug/1
Zn 8000 ug/1
PCP (an individual organic) is the only compound that commonly exceeds these standards in several
wells. Additionally, dioxin at levels exceeding the standard has occasionally been found at on-site
wells.
12
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4.0 FINDINGS AND OBSERVATIONS FROM THE RSE SITE VISIT
4.1 FINDINGS
In general, the RSE team found the system to be well operated and maintained. The observations and
recommendations given below are not intended to imply a deficiency in the work of either the
designers or operators, but are offered as constructive suggestions in the best interest of the EPA and
the public. These recommendations obviously have the benefit of the operational data unavailable to
the original designers.
4.2 SUBSURFACE PERFORMANCE AND RESPONSE
4.2.1 WATER LEVELS
Although water levels are routinely monitored (at least monthly), detailed water level maps have not
been produced under pumping conditions (except in informal and/or draft format). It should be noted
that the design of this system is well suited for detailed water level analysis, because pumping wells
generally have adjacent piezometers and rehab wells for water level measurements.
4.2.2 CAPTURE ZONES
In addition to the fact that water level maps have not been produced, there has been no real attempt
made to date to formally compare observed capture zones (based on equipotentials) with a target
containment zone. No superposition of water levels with a target containment zone was reported. It
should be noted, however, that this is a relatively recent system (OU3 has operated only about a year),
and most effort to date has focused on getting the system operational.
4.2.3 CONTAMINANT LEVELS
A clear summary was not presented detailing whether or not contaminant concentrations have
increased or declined in the aquifer. It should be noted, however, that this is a relatively recent
system (OU3 has operated only about a year).
4.3 TREATMENT SYSTEM DOWN-TIME
There have not been significant problems with system down-time, although individual wells are
sometimes down for various reasons.
4.4 COMPONENTS OR PROCESSES THAT ACCOUNT FOR MAJORITY OF
COSTS
A cost breakdown was provided for the first 11 months of OU3 system operation. This totaled about
$300,000 after subtracting one time plan preparation fees; however, general consulting fees
13
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(reportedly over $150,000) were not included in this total. Expected future O&M costs are about
$395,000 per year, if consulting/reporting fees can be held to $90,000 per year.
A rough estimate of annual costs of $140,000 per year, including consulting fees, was provided for
OU2. A breakdown of approximately $70,000 for the system operation and $70,000 for
consulting/reporting was reported.
OU2
OU3
Estimated Annual
Consulting
$70K/yr
$90K/yr
Estimated Annual
O&M
$70K/yr
$305K/yr
Total Estimated
Annual Cost
$140K/yr
$395K/yr
4.4.1
UTILITIES (OU3 ONLY, DETAIL FOR OU2 NOT PROVIDED)
Based on the first 11 months of operation, annual electric costs are expected to be $18,000.
Electricity powers the well pumps, transfer pumps, mixers, compressor, blowers, and building heat.
Annual natural gas costs are expected to be about $21,000. A natural gas boiler is used for the heat
exchanger to preheat groundwater prior to the bioreactor.
POTW discharge fees are expected to be about $73,000 per year based chiefly on volume rates.
Telephone charges are expected to be about $3,000 per year. Total utility cost are estimated at
$115,000 per year.
4.4.2 NON-UTILITY CONSUMABLES AND DISPOSAL (OU3)
The following items and approximate expected annual cost are included in this category:
Replace Liquid Phase GAC
Replace Vapor Phase GAC
Bag Filters
Sludge Disposal
Product Disposal
Sodium Hydroxide
Nutrients
Polymer
TOTAL
$16,000
$ 5,500
$14,400 (200 filt/mo x $6/filt x 12 mo = $14,400)
$10,000
$ 1,500
$ 2,000
$ 9,000
$ 500
$58,900
4.4.3 LABOR (OU3)
Two Carbonair technicians working a combined total of 30 hours per week are responsible for
treatment system operation and periodic water level measurement. This function costs about $42,000
per year. Additional labor required for sampling and analysis and maintenance is discussed below.
14
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Consulting costs during the first year of operation were reportedly over $150,000 due in part to start-
up issues. These costs are expected to be reduced to about $90,000 beginning with the second year of
operation.
Total labor costs will be about $130,000 per year.
4.4.4
SAMPLING AND ANALYSIS (OU3)
For OU3, monthly effluent sampling is conducted for PAHs, phenols, dioxin, arsenic, chromium,
copper, COD and TSS at six discharge locations at a cost of about $60,000 per year. Select
performance samples are taken and analyzed at points in the treatment plant process at an additional
cost of about $20,000 per year. Total sampling and analysis costs are therefore $80,000 per year.
4.4.5 OTHER COSTS (OU3)
Undefined maintenance issues are indicated to require an additional $30,000 per year.
4.4.6
SUMMARY OF TOTAL COSTS
An estimate of total costs for the OU2 and OU3 systems is as follows (these are approximations based
on somewhat limited data, and do not include system wide aquifer monitoring):
Item
Consulting OU2
Consulting OU3
Labor (O&M, Combined OU2 and OU3)
Utilities OU3
Consumables OU3
Process/Discharge Sampling OU3
Other OU2
Other OU3
Total (w/out aquifer monitoring)
Estimated Annual Cost
$70K/yr
$90K/yr
$40K/yr
$115K/yr
$60K/yr
$80K/yr
$50K/yr
$30K/yr
$535K/yr
4.5 RECURRING PROBLEMS OR ISSUES
4.5.1 BAG FILTERS
The original system design for OU3 included four bag filters; 10 are online currently. The five
micron bags in use must be changed out on a daily basis (sometimes twice daily) to maintain flow
through the treatment system. Filter usage is approximately 200 filters/month at a cost of $6.00 per
bag. The fouling of the bags is mainly due to sloughed biological growth from the fixed film
15
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bioreactor which is not captured in the clarifier. The clarifier has been largely ineffective in removing
this material.
4.5.2 PRODUCT RECOVERY, OU2
The automated product recovery pump for OU2 has never worked properly, and product is therefore
removed with hand-bailing.
4.5.3 PIPING CLOGGING
There have been problems with pipe clogging in the OU3 plant, and there was a change from small
pipe to 3" pipe to reduce clogging. Also, the procedure of sending filtrate to the influent tank was
stopped to hopefully reduce piping fouling.
4.5.4 RADIO CONTROLLERS AND WELL CYCLING
There have been some problems with the reliability of the radio controlled pumps and the cycling of
wells. EW-15 is low producer, for instance, and this may be due to a communication problem with
EW-15. Wells are currently cycled on and off based on a single level. The situation might be
improved if a high and low fluid level was used.
4.5.5 BlOFOULING AT WELLS
There has been biofouling problems with some wells. Monitoring specific capacity of the extraction
wells is performed, and when a decrease is noted, rehab is performed using NuWell from Johnson
Screen. There has also been biofouling problems with OU2 pump.
4.5.6 HEAT EXCHANGER
Heat exchanger cleanings (OU3) have required more operation and maintenance time than expected.
Scale and biological fouling in the heat exchanger has required cleaning at least twice monthly to
maintain flow to the bioreactor. Note the heat exchanger is not used for OU2.
4.5.7 TREATMENT SYSTEM FLOW RATE
Pumping of extraction wells appears to be limited by the treatment system design/operating limit of
50 gpm. Greater capacity within the treatment system would allow more flexibility in extraction well
pumping rates and drawdowns. Greater capacity in the treatment system may be possible if the heat
exchanger and bag filter issues are resolved. However, as the oil water separator and bioreactor are
both rated for 50 gpm, the potential increase is minor based on current system configuration. If in the
future the rate limit of the O/W separator is a limiting factor (i.e., if the bioreactor is removed from
the treatment process), it may be possible to modify piping so fewer wells feed into the O/W
separator.
4.5.8 EW8
Initial pumping of EW8 indicated considerable free product (LNAPL and possibly DNAPL).
Pumping from the well was terminated immediately when this was discovered (to avoid damaging the
OU3 biomass) and this well is still inactive. The well could be pumped, possibly with a pneumatic
pump for several days, with product recovered and water treated (possibly in the OU2 system which
has excess capacity) until it can be returned to the OU3 system.
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4.6 REGULATORY COMPLIANCE
No regulatory compliance problems were noted.
4.7 TREATMENT PROCESS EXCURSIONS AND UPSETS, ACCIDENTAL
CONTAMINANT/REAGENT RELEASES
The heat exchanger and/or discharge pump has leaked historically in the OU2 plant. There appears to
be minor problems with leakage in the OU3 influent tank.
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
It is not clear whether or not the off-site plume is being effectively captured by the current extraction
system. Although the aquifer cleanup goal for PCP is 1 ug/1, the current target currently used for
containment is 50 to 100 ug/1. The protectiveness afforded by the 50 to 100 ug/1 target has not been
formally assessed.
5.2 SURFACE WATER
If the off-site plume is not being effectively captured, then there is a potential threat to streams,
wetlands, and lakes. For instance, the OU3 ROD indicated that PCP was detected in surface water
and sediments of Parrel's Lake (northeast of the site), although it is not clear whether or not the
MacGillis site is the cause.
5.3 AIR
A blower transports vapors from the water treatment vessels to a vapor phase carbon unit prior to
discharge to the atmosphere. A standard operating procedure should to be developed to sample the
discharge of the vapor phase carbon unit to confirm protectiveness.
5.4 SOILS
Not a focus of this RSE.
5.5 OTHER
The site is currently not fenced. There is debris on the site, plus an open (potentially contaminated)
pond and an exposed gasoline pipeline.
It was discussed during the site visit that there is a plan for Donatelle (office building immediately
north of the site) to expand, with another office building to be constructed on the site. This may lead
to an office building built directly over free product. It is not clear that this has been evaluated in
detail with respect to construction workers and building occupants. It is also not clear if this will
impact the OU2 extraction well, and therefore potentially compromise LNAPL containment at the
northeast site boundary.
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6.0 RECOMMENDATIONS
6.1 RECOMMENDED STUDIES TO IMPROVE EFFECTIVENESS
6.1.1 DEVELOP/UPDATE TARGET CONTAINMENT ZONE
Although the aquifer cleanup goal for PCP is 1 ug/1, the current target currently used for containment
is 50 to 100 ug/1. The protectiveness afforded by the 50 to 100 ug/1 target has not been formally
assessed. Now that the system is fully operational, it is an appropriate time to perform these analyses.
It is recommended that a target containment zone for key constituents (PCP, chromium) be developed
and updated annually (based on long-term monitoring data from aquifer monitor wells). Without this
step, the adequacy of the capture zone provided by the extraction system cannot be assessed. If the
target containment zone for PCP is to be substantially higher than the ROD cleanup level of 1 ug/1,
this should be justified based on technical/risk arguments, and then formalized in a ROD amendment.
The target containment zone should take into account potential DNAPL near EW-13 (dissolved hot-
spot) and consider the adequacy of plume characterization near the outer extent of the target
containment zone. Estimated cost is $30K capital (year 1), $5K/yr annual.
6.1.2 CAPTURE ZONE ANALYSIS
At least quarterly, a formalized capture zone analysis should be performed by superposing on one
map the measured equipotentials (with interpreted capture zones) and the target capture zone. A
procedure for review of the results should be established, so that potentially inadequate capture can be
addressed in a timely manner. Estimated cost is $10K/yr.
6.1.3 LONG-TERM MONITORING
Because the system is relatively recent, a long-term monitoring schedule is not yet in place for the
New Brighton aquifer, or for the underlying Hillside aquifer. A long-term monitoring plan should be
developed that indicates which well should be sampled, at what frequency, and for what parameters.
Sampling should be probably occur annually. This monitoring plan should include sampling of
select aquifer monitor wells and individual extraction wells. Extraction flow rates should also be
regularly monitored and reported as part of the long-term monitoring plan. Estimated cost is $40K
capital to develop the plan, and $100K/yr annual to implement the plan.
6.1.4 FENCING/SECURITY AND EXPOSED PIPELINE
There is debris on the site, plus an open (potentially contaminated) pond and an exposed gasoline
pipeline. Access to this site should be restricted until such time as the debris is completely removed,
the pond is filled, and the pipeline is no longer exposed. The pipeline is not currently marked with
appropriate warnings, and this at a minimum should be immediately corrected. Estimated capital cost
$25,000, estimated annual cost of $3K/yr.
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6.1.5 DONATELLE EXPANSION
It was discussed during the site visit that there is a plan for Donatelle (office building immediately
north of the site) to expand, with another office building to be constructed on the site. This may lead
to an office building built directly over free product, and the risk to construction workers and building
occupants should be specifically evaluated. An evaluation should also be performed regarding
potential impacts if the OU2 extraction well is destroyed. Estimated capital cost is $20K.
6.1.6 ATMOSPHERIC DISCHARGE FROM THE WATER TREATMENT PLANT
The atmospheric discharge from the water treatment plant consists of a collection of vapors from the
water treatment vessels and treatment in a vapor phase carbon unit. A standard operating procedure
should to be developed for sampling the discharge of the vapor phase carbon unit (perhaps quarterly
or semi-annually) to confirm protectiveness.
6.2 RECOMMENDED CHANGES TO REDUCE COSTS
6.2.1 SHUTDOWN OU2 SYSTEM
The OU 2 system was an interim system designed to capture LNAPL and the full scale system
(OU 3) required a new treatment plant with significantly larger capacity to treat the entire
contaminant plume. With the successful operation of the OU 3 system now demonstrated, the
opportunity now exists to discontinue operation of the OU 2 treatment plant and treat the OU 2 flow
at the OU 3 facility much more cost effectively. The influent from EW-1 (OU2) could be directed to
the influent tank of the OU3 system. OU2 system components could be used or kept for future use in
the OU3 system or salvaged. Estimated capital cost of $50K, estimated annual savings of $140K/yr
(note the OU2 system is only expected to operate an additional 4 years based on the ROD).
6.2.2 CONSIDER MODIFYING OU3 TREATMENT (ELIMINATE BIOREACTOR)
The bioreactor component of the OU3 treatment system has been very effective to date. This system
yields sufficient removal of PCP (about 10 mg/L at 50 gpm = 6 Ib/day) and carcinogenic PAHs (less
than 0.5 mg/L at 50 gpm = 0.3 Ibs/day). However, this removal occurs at a high price including the
following:
Cost of nutrients, NaOH, polymer to run the bioreactor $11,500
and the clarifier
Cost of fuel to run the heat exchanger $21,000
Cost to dispose of sludge and run the sludge $ 9,000
tank and filter press (90% of sludge disposal)
Excess cost to replace and dispose bag filters $ 7,200
(50% of filters) due to sloughing from bioreactor
Power for above (50% of electric) $ 9,000
Maintenance for above (50% of maintenance) $21,000
Labor for above (50% of operator time) $21.000
TOTAL: $99,700
(***Does not include consulting cost and vapor phase GAC cost)
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Based on current influent concentrations for PCP (which are lower than original design values), an
opportunity may now exist to eliminate the bioreactor and expand the role of GAC (to be the main
treatment component). Currently the GAC is a polishing step for any potential dioxin and a backup
for bioreactor upset. In the revised system, the treatment train would consist of the oil/water
separator, bag filter and liquid GAC only, prior to discharge (organo-clay could potentially be added
prior to GAC if the oil/water separator was not completely effective for product removal). In addition
to being a much simpler system from the operation standpoint, greater flexibility to increase the
system flow rate would be possible as the existing liquid phase GAC units have a 200 gpm capacity.
The only cost that would increase with the elimination of the bioreactor would be the replacement of
GAC due to greater PCP loading. Using 100 mg PCP per Ib. GAC (Nyer, Groundwater Treatment
Technology, 1992), about 22,000 Ibs of GAC would be required per year, yielding a potential
$55,500 savings (Bioreactor costs: $99,700 + Current Liquid Phase GAC Costs: $16,000 - Projected
GAC Costs: $60,200) based on GAC replacement/regeneration cost of $2.75 per pound.
This savings would increase over time as influent concentrations decrease and offsite wells EW5 and
EW13 could be routed directly to the POTW. The GAC usage rate should be evaluated with a bench
or pilot scale test to confirm that these cost savings are likely. Estimated capital cost is $25K,
estimated potential savings is $55.5K/yr.
Another alternate strategy to consider (again possible due to current influent concentrations that are
lower than original design values) is to approach the POTW regarding the potential for them to accept
somewhat higher concentrations than currently, and avoid treatment altogether (including the GAC).
This would require sampling for dioxin at specific locations to confirm they are NDs.
6.2.3 REDUCE SAMPLED DISCHARGE POINTS
For the first quarter of 2000, six discharges were sampled monthly with analysis for PAHs, phenols,
dioxin, arsenic, chromium, copper, COD and TSS. Samples from EW14 and EW16 are collected and
analyzed separately for all these parameters on a monthly basis even though the discharge from both
wells is to the same manhole.
The discharges could be retrofitted so that EW14, EW12, EW15, and EW16 are combined. For the
cost of installing about 500 feet of piping, three separately sampled discharges would be eliminated
and $30,000 per year saved. Select parameters (PCP) could be analyzed at each well on a less
frequent basis for performance monitoring needs. Estimated capital cost of $30K, estimated savings
of $30K/yr. Potentially, all extraction wells could be routed to the OU3 building for one common
discharge point, with even greater savings.
6.3 MODIFICATIONS INTENDED FOR TECHNICAL IMPROVEMENT
Additional recommendations intended for technical improvement include:
Replace the pH sensor on the OU3 bioreactor to avoid requirement for operator to
climb ladder.
Revising the well rehabilitation program to consider specific treatments to fight
biological growth. Current treatment approach may not adequately address the
biological issues. Suggest the operator diagnosis the fouling problem using BART
tests and select the rehabilitation technique that is appropriate to the type of bacteria.
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7.0 SUMMARY
In general, the RSE team found the system to be well operated and maintained. There are several
protectiveness issues that should be addressed, most notably establishing a target containment zone
and regularly evaluating the actual capture zone with respect to the target. The anticipated costs of
implementing these and other recommendations related to protectiveness are summarized on the
following "Cost Summary Table" (Table 7-1).
Several recommendations are also made to potentially reduce future operations and maintenance
costs. These opportunities to reduce cost arise from the fact that the OU3 system is now fully
operational, and influent concentrations are lower than originally designed for. The recommendations
include eliminating the OU2 treatment system (potential net savings of approximately $0.5M over the
remaining 4 years of expected operation for the OU2 system, non-discounted), and potentially
eliminating the bioreactor from the OU3 treatment system, subject to a pilot-test and a cost/benefit
analysis (potential net savings of more than $1.5M over 30 years). The anticipated costs and potential
savings of implementing these and other recommendations to reduce costs are also summarized on
the "Cost Summary Table" (Table 7-1).
Table 7-1. Cost Summary Table
Recommendation
Develop/update target capture zone
Capture zone analysis
Long-term monitoring
Fencing/security & exposed pipeline
Donatelle expansion
Vapor Monitoring
Shut down OU2 system
Eliminate bioreactor, OU3
Reduce sampled discharge points
Replace pH sensor, OU3
Revise well rehab program
Reason
Effectiveness
Effectiveness
Effectiveness
Effectiveness
Effectiveness
Effectiveness
Cost reduction
Cost reduction
Cost reduction
Tech. improvement
Tech. improvement
Additional
Capital
Costs
($)
$30,000
$0
$40,000
$25,000
$20,000
$2,000
$50,000
$25,000
$30,000
$500
$10,000
Estimated
Change in
Annual
Costs
($/yr)
$5,000
$10,000
-
$3,000
$0
$2,000
($140,000)**
($55,500)
($30,000)
$0
$3,000
Estimated
Change In
Lifecycle
Costs
($)*
$180,000
$300,000
***
$115,000
$20,000
$62,000
($510,000)**
($1,640,000)
($870,000)
$500
$100,000
* Estimated change in life-cycle costs assumes 30 years, no discount rate, except where noted.
** Assumes 4 years additional operation for OU2 system, based on ROD.
** There is no "cost increase" for the long-term monitoring, since monitoring is anticipated, just not
yet implemented. Annual costs are estimated to be $100,000 for a life-cycle cost of
$3,040,000.
(1) Costs in parentheses imply a cost reduction.
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N
EW15
EW1 4-
EW1,
EW1:
BELL LUMBER & POLE
PROPERTY PARCEL 1
BELL LUMBER & POLEr
PROPERTY PARCEL 2
i '/
I /
3TES:
1. PREPARED FOR RSE BASED
450
900
PEET
WATER LEVELS EROM DECEMBER
20, 1992.
Figure 1.1 Site Location and Groundwater High Near the Pond,
MacGIIIis & Gibbs, New Brighton, Minnesota.
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Solid Waste and
Emergency Response
(5102G)
542-R-02-008C
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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