Tutu Wellfield Superfund Site
Proposed Cleanup Plan for Groundwater 
Remediation at the Curriculum Center
Pre-Recorded Presentation
July 14, 2021
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Donette Samuel, Community 
Involvement Coordinator
Meeting Presenters
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Caroline Kwan, Remedial 
Project Manager
Conclusions of the Focused Source Remedial 
Investigation, Risk Assessment and Feasibility Study 
Revisions to the 2018 Proposed Plan with updated cost-
benefit analysis
Proposed Plan for the cleanup of the contaminant source 
areas of the Tutu Wellfield site
Public is encouraged to provide comments until August 
13th, 2021
Presentation Objectives
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Meeting Agenda
Superfund Overview
Site Background
Remedial Investigation
Risk Assessment 
Feasibility Study
Preferred Remedy
Questions/Comments?
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Toxic waste disposal disasters prompted law passage 
by Congress in 1980
Provides Federal funds for cleanup of hazardous waste 
sites 
Allows EPA to respond to emergencies involving 
hazardous substances
Empowers EPA to compel Potentially Responsible 
Parties to pay for or conduct site clean up
Superfund Law 
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Superfund Cleanup Process
WE ARE HERE
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Meeting Agenda
Superfund Overview
Site Background
Remedial Investigation
Risk Assessment 
Feasibility Study
Preferred Remedy
Questions/Comments?
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Location of Tutu Wellfield Superfund Site
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1969: Curriculum Center property owned by LAGA 
Industries Ltd. (LAGA), a textile manufacturing facility
1970 – 1978: Purchased by Duplan Corporation. Begun 
dry cleaning operations using Tetra-chloroethene (PCE)
Site History
1979 – 1981: Purchased by Panex, sold to Virgin 
Islands Department of Education (VIDE)
1982 – 2017: Multi-use building by VIDE
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1982 – 1989: Multiple investigations by EPA and 
Potentially Responsible Parties (PRPs)
1994 – 1995: Remedial Investigation (RI) identified co-
mingled plumes with chlorinated volatile organic 
compounds (CVOCs) and petroleum/gasoline components
Site History
1995: Site listed on the National Priorities List (NPL).
Studies concluded that the CVOC plume with dichloro-
ethene (DCE), tetrachloroethene (PCE), trichloroethene 
(TCE), and vinyl chloride (VC) originated at or near the 
Curriculum Center
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1996: Record of Decision (ROD) for sitewide remediation 
selected groundwater extraction and treatment to restore  
groundwater
2004-2013: Construction of the remedy completed and 
included two groundwater treatment systems to treat the 
CVOC plume. Groundwater treatment facilities operated by 
EPA; transferred to USVI in 2013
Site History
April 2015: EPA’s Operable Unit 2 (OU2) investigates 
potential additional contaminant source areas
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Status of Sitewide Remediation 

Current Remedy: Groundwater 
extraction, ex-situ treatment, 
discharge to Turpentine Run, 
and institutional controls

Groundwater treatment 
systems installed at the 
Curriculum Center property and 
near O’Henry Dry Cleaners 

SVE system installed at the 
Curriculum Center and 
operated from 2004 to 2006; 
vapor contamination was 
reduced significantly 

Insufficient reduction of 
groundwater contamination at 
the Curriculum Center area
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Meeting Agenda
Superfund Overview
Site Background
Source Area Remedial Investigation
Risk Assessment 
Remedial Alternatives
Preferred Remedy
Questions/Comments?
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Source Area - Curriculum Center Property
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Source Area Remedial Investigation
Activities conducted at the Curriculum Center property 
April 2016 to June 2017
Surface geophysical survey
Rock matrix diffusion sampling and analysis
Monitoring well installation
Borehole geophysical investigation
Packer testing and sampling
Groundwater sampling
Groundwater level monitoring
Dense non-aqueous phase liquid (DNAPL) monitoring 
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Source Area Groundwater Sampling Results

Characterized bedrock aquifer; defined two possible zones for 
contaminant migration 

DNAPL is present and will act as an ongoing source 

Dissolved phase CVOC contamination is present 

Contaminants present in the rock matrix will continue to leach 
out into groundwater 

The degree of natural degradation varies throughout the 
Curriculum Center area

The capture zone of the existing extraction system does not 
extend far enough in a downgradient direction
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Monitoring Well Exceedances Summary
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Conceptual Site Model
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Hurricane Irma and Maria Impacts

The two sitewide groundwater (GW) treatment systems were damaged 
during hurricanes Irma and Maria and remained shut down due to 
electrical problems

Repairs were completed in 2020 and the system were placed in 
operation in June 2021

Contamination continue to migrate downgradient

To assess the impact of the treatment systems shutdown, supplemental  
GW sampling was performed in June and October 2019 and the findings 
are:

Analytical results confirmed the extent of chlorinated compounds in GW.

Concentrations in samples from Curriculum Center wells were generally lower than 
those established in the 2017 Remedial Investigation (RI).

Concentrations detected in residential wells were generally below MCLs. One sample 
exceeded an MCL for TCE and that well is used for irrigation purposes only. 

Comparison of the 2017 & 2019 GW Sampling Data, is presented on the next figure:
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Meeting Agenda
Superfund Process Overview
Site Background
Remedial Investigation
Risk Assessment
Remedial Alternatives
Preferred Remedy
Questions/Comments
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Source Area Risk Assessment Process
Step 1 • Hazard Identification
Step 2 • Exposure Assessment
Step 3 • Toxicity Assessment
Step 4 • Risk Characterization
Drinking Water Use Pathway
Source: Thinkstock Photos
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Source Area Risk Assessment Summary
Contaminated groundwater presents an unacceptable 
exposure risk
VC, TCE, PCE and cis-1,2-DCE pose a lifetime cancer 
risk exceeding 1x10-4
Vapor intrusion from PCE and TCE are also of potential 
concern to workers 
Future use of the building is currently unknown
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Meeting Agenda
Superfund Process Overview
Site Background
Remedial Investigation 
Feasibility Study
Preferred Remedy
Questions/Comments?
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Remedial Alternatives – Cleanup Options

Alternative 1 – No Action

Alternative 2 – Expand Existing Pump and Treatment System

Alternative 3 – In Situ Thermal Treatment and Pump and Treat

Alternative 4 – In Situ Steam Injection and Pump and Treat
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Alternative 1 – No Action
•
No Action to remediate the contaminated groundwater
•
No Institutional Controls
Pros – Basis for comparison with other process options
Cons – Contaminants in groundwater will continue to spread. Human health and 
environmental risks remain
Costs-
•
Capital Cost: $0
•
Operations and maintenance (O&M) Costs:  $0
•
Present-Worth Cost:  $0
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August 2018
Alternative 2 – Expand Existing Pump and
Treat System
• Alternative 2A – Reinjection
• Alternative 2B – Air Sparging/Soil Vapor Extraction (AS/SVE)
• Alternative 2C – In Situ Chemical Oxidation (ISCO)
• Alternative 2D – Surfactant Flushing
Alternative 2 – Expand Existing Pump and Treat System
•
Expand existing system, add two new 
extraction wells downgradient 
•
Upgrade current system capacity
•
Replace existing equipment
•
Alternate pumping from source area wells
•
Dual-phase extraction (DPE) / enhanced fluid 
recovery (EFR) from source area wells
Pros - containment of plume; removal of DNAPL
Cons - remedial timeframes are long
Timeframe-
•
Estimated to be in excess of 30 years;
•
Pump and treat (P&T) and long term 
monitoring (LTM) costs estimated for 30 years.
Costs-
•
Capital Cost: $4,802,538
•
Operations and maintenance (O&M) Costs:  
$8,481,677
•
Present-Worth Cost:  $13,340,565
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Alternative 2A – Reinjection
Enhancement of Alternative 2 with reinjection 
of treated water downgradient through two 
new injection wells
Pros- better hydraulic control and maintaining 
water balance
Cons - additional hydrogeological analysis 
needed; reinjection wells will need 
maintenance; long remedial timeframes
Timeframe -
•
Estimated to be in excess of 30 years; 
•
P&T and LTM costs estimated for 30 
years.
Costs-
•
Capital Cost: $437,053
•
O&M Costs: $51,364 plus Alt 2
•
Present-Worth Cost: $488,417
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Alternative 2B – AS/SVE
Enhancement of Alternative 2 with air sparging and 
soil vapor extraction (AS/SVE) in source areas; add 
25 SVE and 30 AS wells
Pros- mobilize residual DNAPL within the zone 
influenced by air sparging; may increase the mass 
removal rate reducing the timeframe of the P&T 
system 
Cons- air flow may not be uniform, depends on how 
well the injected air permeates from injection point, 
connectivity of fractures and groundwater mounding
Timeframe-
•
The AS/SVE system at source area for 5 years; 
•
Based on calculations, downgradient area will 
reach drinking water standards in 25 years; 
•
LTM costs estimated for 30 years
Costs -
•
Capital Cost: $1,739,745
•
O&M Costs: $205,461 plus Alt 2
•
Present-Worth Cost: $1,945,206
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Alternative 2C – ISCO
Enhancement of Alternative 2 with in situ 
chemical oxidation (ISCO) cylinders in select 
source area wells; 64 cylinders in 12 
monitoring wells; replaced yearly
Pros- passive treatment for source area 
concentrations; less expensive
Cons - will affect the bioactivity in the aquifer 
Timeframe -
•
ISCO at source area for 5 years;
•
Based on calculations, downgradient 
from treated source area will reach 
drinking water standards in 25 years; 
•
LTM estimated for 30 years
Costs-
•
Capital Cost: $99,364
•
O&M Costs: $117,110 plus Alt 2
•
Present-Worth Cost: $216,474
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Alternative 2D – Surfactant Flushing
Enhancement of Alternative 2 with surfactant 
flushing in source areas; two deep injection 
wells, five shallow injection wells
Pros - removal of source area concentrations 
and DNAPL 
Cons- effective only if there is contact; ability of 
the formation to accept a sufficient volume of 
surfactant solution is unknown
Timeframe -
•
Surfactant flushing at source area for 1 
year; 
•
Based on calculations, downgradient from 
treated source area will reach drinking 
water standards in 25 years; 
•
LTM estimated for 26 years.
Costs -
•
Capital Cost: $1,265,756
•
O&M Costs: Same as Alt 2
•
Present-Worth Cost: $1,265,756
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Alternative 3 – In Situ Thermal Treatment and 
Pump and Treat System
•
In situ thermal treatment to target DNAPL in 
source areas and pump and treat for 
hydraulic control; 260 to 270 heater wells, 
co-located with 260 to 270 vacuum 
extraction points
•
Add two downgradient extraction wells and 
upgrade the current treatment system 
capacity and equipment
Pros - ability to penetrate fractured rock matrix 
and to treat DNAPL and CVOCs
Cons - high capital costs 
Timeframe -
•
Thermal at source area for 2 years; 
•
Based on calculations, downgradient from 
treated source area will reach perimeter 
P&T wells in 10 years; 
•
LTM estimated for 12 years.
Costs-
•
Capital Cost: $89,628,605
•
O&M Costs: $4,569,283
•
Present-Worth Cost: $94,309,778
Alternative 4 – In Situ Steam Injection and 
Pump and Treat 
•
In situ steam injection in source areas to 
release DNAPL with pump and treat for 
hydraulic control, 60 steam injection wells and 
30 multi-phase extraction wells
•
Add two downgradient extraction wells and 
upgrade the current treatment system capacity 
and equipment
Pros - mobilize DNAPL which will be captured by 
the extraction wells
Cons - effectiveness of steam injection relies on its 
ability to contact, heat, and physically displace 
contaminants; high capital costs
Timeframe-
•
Steam treatment at source area for 2 years; 
•
Based on calculations, downgradient from 
treated source area will reach drinking water 
standards in 25 years; 
•
LTM estimated for 27 years
Costs-
•
Capital Cost: $25,568,569
•
O&M Costs: $8,539,451
•
Present-Worth Cost: $34,171,200
Remedial Alternatives – Common Elements for 
Alternatives 2, 3 and 4

Pre-Design Investigation 
(PDI) 

Institutional Controls

Upgrade the current 
system 

Long-term monitoring 
until clean up levels are 
achieved

Site Management Plan

Five Year Reviews
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EPA’s Nine Criteria 
for Selecting Cleanup Plans
EPA uses nine criteria to evaluate remedial 
alternatives presented in the Feasibility 
Study and choose which to implement. The 
nine criteria are organized into 3 groups:
1.
Threshold Criteria
2.
Balancing Criteria
3.
Modifying Criteria
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Threshold Criteria 
1.
Overall Protection of Human Health and 
the Environment: Will the plan protect people and 
the plant and animal life on and near the site? EPA cannot 
and will not choose a plan that does not meet this basic 
criterion.
2.
Compliance with Applicable or Relevant 
and Appropriate Requirements: Does the 
alternative meet all federal and state environmental 
statutes, regulations and requirements? The chosen 
cleanup plan must meet this criterion.
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Balancing Criteria 
3.
Long-Term Effectiveness and Permanence: Will the effects of the 
cleanup last or could it be ineffective and cause future risks?
4.
Reduction in Toxicity, Mobility or Volume through Treatment: Does 
the alternative reduce the harmful effects, spread of, and amount 
of the contaminated material?
5.
Short Term Effectiveness: How soon will site risks be reduced? 
Could the cleanup cause short-term hazards to workers, residents 
or the environment?
6.
Implementability: Is the alternative technically feasible? Are the 
right goods and services (i.e. treatment machinery, space at an 
approved disposal facility) available to complete the plan?
7.
Cost: What is the total cost of an alternative over time? EPA must 
choose a plan that gives necessary protection at reasonable cost.
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Modifying Criteria 
8.
State/Territory Acceptance: Do state/territory 
environmental agencies agree with EPA’s proposal?
9.
Community Acceptance: Acceptance of preferred 
alternative by the impacted community will be 
assessed following the public comment period.  
Provide your comments.
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Meeting Agenda
Superfund Overview
Site Background
Remedial Investigation 
Remedial Alternatives
Preferred Remedy
Questions/Comments
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Preferred Remedy - Alternative 2 , Expand Existing 
Groundwater Extraction and Ex-Situ Treatment (Pump and 
Treat) with Alternative 2A, Reinjection
Expand existing pump and treat system to include downgradient extraction wells;
Upgrade pump and treat system to higher flow rate;
Upgrade all treatment equipment to accommodate additional flow and improve efficiency; 
Reinject treated water;
Alternate pumping from existing monitoring wells with high contaminant concentrations;
Dual phase extraction from source area wells; and,
Long-term groundwater monitoring.
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Contingency Remedy - Alternative 2 , Expand Existing 
Groundwater Extraction and Ex-Situ Treatment 
(Pump and Treat) with Alternative 2B, AS/SVE
Expand existing pump and treat system to include downgradient extraction wells;
Upgrade pump and treat system to higher flow rate;
Upgrade all treatment equipment to accommodate additional flow and improve efficiency; 
Air Sparging/SVE at source areas; and,
Long-term groundwater monitoring.
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Questions and Comments?
To request a copy of the Proposed Plan or 
subscribe to the Tutu Wellfield Superfund site’s 
email list for the latest updates, contact:
Donette Samuel
Community Involvement Coordinator
E-mail: samuel.donette@epa.gov
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Questions and Comments?
Please address written comments no later than  
August 13, 2021, to:
Caroline Kwan
Remedial Project Manager
U.S. Environmental Protection Agency 
290 Broadway, 18th Floor
New York, NY  10007-1866
E-mail: kwan.caroline@epa.gov
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Thank You!
Thank you for watching the Tutu Wellfield 
Superfund site Pre-Recorded Presentation. 
For more information about the site, visit: 
https://www.epa.gov/superfund/tutu-wellfield
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