ElMSltlm 
ENSR
anil Engineering
/****" 
35 Najzoi: Park
Acton. MA 01720
January 10, 1994 
<5o«) 633-<>5oo
FAX (.508) 635-yi80
ENSR Ret. No: 7218-001-210
ENSRDoc. No: 22-JMB-113
Mr. Clifford Crooke
Environmental Specialist
Government of the US Virgin Islands
Department of Planning and Natural Resources
Division of Environmental Protection
Suite 231, Nisky Center
St. Thomas, U.S.V.I 00802
RE: 
Addendum to Site Assessment/Remediation
Work Plan- Dated November 30, 1993
Western Auto - Four Winds Plaza
St Thomas, USVI
Dear Mr. Crooke:
On November 30, 1993, ENSR Consulting and Engineering submitted a Site
Assessment/Remediation Work Plan on behalf of Western Auto for a facilty they operate at
the Four Winds shopping plaza, Tutu, USVI. The purpose of this letter is to present an
addendum to our November 30 work plan.
The work plan was designed by ENSR, based on the requirement made by the Department
of Natural Resources (DPNR), to determine the vertical and horizontal extent of oil
contamination at the site. 
In order to comply with DPNR's requirement additional
investigation work is necessary. The additional work tasks purposed in this addendum
would allow us to verify and supplement the results of our recently completed soil screening
survey (described below). Soil screening survey data is typically used in a site investigation
to delineate the horizontal extent of contamination. The results are a measure of the soil
gas concentrations and are not actual concentrations of contaminants in the soil; therefore,
these data provide a relative indication of likely zones of contamination. Several soil
samples will be collected based on the results of the screening survey and analyzed in a
laboratory by EPA methods for volatile organic compounds (VOC) and semivolatile organic
compounds (SVOC). If free product is observed, then a petroleum fingerprint analysis would
also be performed to identify its type.
In this case the soil screening results indicate potential source areas, but the surveyed area
must be expanded in order to complete the investigation. For example, at sorber location
TUT 
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13O1
*64751*
64751
January 6, 1994
Mr. Clifford Crooke
Department of Natural Resources
Page 2
GS-16 (refer to Figure 1) the presence of heavy oil constituents were reported at 226143 ion
counts of a C18H20 compound, but additional data points in a northern direction are
required to define the extent of the vapor plume. These data points will be added in the
proposed next phase of the survey along with the collection of soil samples to measure soil
contaminant concentration levels. To assist with the location of additional points the four
inch PVC pipe labeled Pipe "C" on Figure 1 will be traced under the building in a northern
direction from the Western Auto loading dock area. The results of the first phase of the soil
screening survey along with an explanation of the next phase of investigation are described
below.
1.0 RESULTS OF PHASE 1 - TASKS 1 & 2
The work scope undertaken by ENSR on behalf of Western Auto was described in a letter
to you dated November 12, 1993, and verbally discussed prior to completion of the field
work during November 15-17,1993.
Task 1 Pipe Tracing: Involved tracing PVC pipelines which had been identified during the
UST closure work. The results of the tracings are shown in approximate location on Figure
1. The pipe labeled as "A" is 4 inch-diameter PVC and was part of the former oil/water
separator located in service bay 1. This pipe was found to run approximately 12.5 feet east,
then 10.5 feet south and then east towards a manhole in front of Western Auto. It was
confirmed, based on a tracing dye test, that this pipe is connected to the sewer line in front
of the Western Auto store.
The pipe labeled "C" is the 4 inch-diameter PVC pipe severed during the removal of the
waste oil tank (UST1). After locating the end of the pipe the cap was unscrewed. After
opening pipe "C", grey water and black liquid entered the pit hole under gravity. The pipe
was then traced: it was found to run 85-90 feet north with no bends. This was as far as the
100 foot plumbers snake would penetrate. Subsequent to ENSR's effort, representatives
of Four Winds Plaza have undertaken additional excavation and pipeline tracing activities;
which have not successfully identified the source of the product.
The pipe labeled "B" was traced and found to be connected to a 6 inch-diameter roof water
collection/cistern system.
Task 2 Soil Screening: ENSR personnel deployed a total of 20 passive sorbent collection
modules, in 1-inch drilled holes to depths of approximately 24-34 inches. The survey was
conducted in the vicinity of the Western Auto store, Figure 1 is a map indicating the location
TUT 
006
January 6, 1994
Mr. Clifford Crooke
Department of Natural Resources
Page 3
of each installed sorber. One sorber GS-19 could not be located and therefore was not
analyzed.
The screening modules (sorbers) consist of approximately 100 mg of a hydrophobic carbon
specifically designed for collecting organic vapors. 
The sorbent containers and
insertion/retrieval cords were constructed of Gore-Tex expanded polytetrafluoroethylene
(EPTFE). The dominant mechanism of analyte transport into the sorbers is vapor transfer
through the microporous walls of the EPTFE insertion cord and sorbent container. A
copy of the Standard Operating Procedures for the Gore-Sorber screening modules is
attached.
The sorbers were installed and left in-place for a period of about two weeks. The sorbers
were then removed from the ground, sealed in glass vials and shipped on ice to W.L Gore
Analytical Laboratory in Elkton, Maryland. The carbon sorber modules were thermally
desorbed at the laboratory and a samples collected which were then analyzed by capillary
gas chromatography with a mass selective detector (MSD).
The results indicate that a potential source of heavy molecular weight constituents are
present to the north of the Western Auto store, directly beneath the shopping center
buildings. Upon completion of the expanded survey along with the results of the soil sample
collection and analysis (described below) a definitive analysis of these data along with
completed maps of results will be provided to DPNR in a letter report.
2.0 PHASE 2 - WORK PLAN
Task 1 Underground Pipeline Tracing
Pipeline "C", 4 inch-diameter PVC (refer to Figure 1), will be traced further under the building
to the north. It was this pipe that was severed by the excavator during the waste oil tank
removal and found to contain a mixture of water and medium to heavy weight oil. The pipe
will be traced with an electronic device attached to the end of a 100 foot sewer/drain
cleaning snake. The device emits a signal that is detected by a hand-held receiver at the
surface. The line will be traced as far as feasible with this technique and based upon this
information task 2 will be conducted.
Task 2 Soil Screening
A second grid of passive sorbent collection devices (sorber) will be installed in the vicinity
of the Four Winds shopping mall. This grid will be established on approximately a 75-200
TUT 
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January 6, 1994
Mr. Clifford Crooke
Department of Natural Resources
Page 4
foot spacing (total of between 25-30 sorbers) to provide adequate coverage. The results will
be incorporated into the survey results reported in this letter and will assist in understanding
the distribution and source of the oil. The sorbers will be installed with hand held tools, left
in place for one to two weeks and then removed and analyzed in a laboratory. These
sensors will detect the presence of volatile and semivolatile compounds, the results will be
expressed as relative concentrations and presented on a site map.
Task 3 Soil Sampling and Analysis
Soil samples will be collected at several locations to quantify concentrations of VOC and
SVOC in the soil. The soil samples will be collected from a sampler, driven by a portable
auger drill, or manually driven. Samples will be screened with a photoionization detector
(PID) and collected at a depth of approximately 2-3 below the ground surface. This
information will be used to calibrate the soil gas concentrations collected during the soil
screening survey. Three locations, identified in Figure 1, will be sampled. These three
samples will be collected at the same time at the additional sorbers are installed.
Once the results of the second survey are completed and evaluated an additional 3-4
locations, identified by the screening survey, will be sampled. The second set of soil
samples will be collected using a portable drilling apparatus or a manually driven sampler.
These samples will be collected from two depths so that the vertical extent of contamination
can be determined; one sample will be collected at a depth of 2-3 feet below the ground
surface, and the second sample will be collected from the bottom of the boring at auger
refusal. Drilling will be continued until auger refusal is encountered. A portable tripod
mounted auger drill rig will be used, inside the shopping mall buildings, to drive and collect
this set of soil samples. 
Again, these data will allow for the soil screening data to be
correlated to actual soil concentrations and to identify the nature and extent of the oil
contamination. The samples will be analyzed in a laboratory by EPA Methods for VOC and
SVOC.
A complete report documenting the results of work plan tasks will be submitted to DPNR
within 6 weeks of our receipt of analytical testing results.
ENSR would like initiate the scope of work identified by the work plan and this addendum
immediately. Please review this proposed scope of work and provide us with any comments
or your permission to initiate this work. We hope start work on the week of January 24,
1994 with your permission.
TUT 
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13O4
January 6, 1994
Mr. Clifford Crooke
Department of Natural Resources
Page 5
If you have any questions regarding these activities please call John Bierschenk at (508)635-
9500 or Bill Sarriera (809)753-9509.
Sincerely,
Jonn Bierschenk
Cpplications Engineer
^^Iw^X7
•w/~
Illiam Sarriera
General Manager
cc: 
John Coon - Amerling & Burns
Bill Chapman - Coon & Stanford
Don Galya - ENSR
Carolyn Kwan - USEPA Superiund Division
TUT 
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13O5
ENSR Consulting and Engineering
Appendix A
Gore Sorber™
Screening
Module
Installation
SOP
TUT 
006 
1306
EPA REGION II
SCANNING TRACKING SHEET
DOC ID #64751
DOC TITLE/SUBJECT:
TUTU WELLS SUPERFUND SITE
FIGURE 1
FIELD SAMPLING LOCATIONS - WESTERN
AUTO SITE ST. THOMAS, U.S. VIRGIN
ISLANDS (Page: TUT 006 1307)
THIS DOCUMENT IS OVERSIZED AND CAN BE
LOCATED IN THE ADMINISTRATIVE RECORD FILE
AT THE
SUPERFUND RECORDS CENTER
290 BROADWAY, 18™ FLOOR
NEW YORK, NY 10007