,'*
C D M 
F E D E R A L 
P R O G R A M S
a s u b s i d i a r y o f C a m p D r e s s e r & M c K e e Inc.
July 8, 1994
Mr. Keith Kollar
U.S. Environmental Protection Agency
26 Federal Plaza
New York, NY 10278
C O R P O R A T I O N
PROJECT:
DOC. NO.:
SUBJECT:
Dear Mr. Kollar:
EPA ARCS Contract 68-W9-0024
Work Assignment 073-2P1D
Tutu Well Field Site
7720-073-EP-BZQZ
Revised Pathway Exposure Report
Draft Endangerment Assessment
DCN: 7720-073-LR-BZQY
CDM Federal Programs Corporation (COM Federal) is pleased to submit the document titled "Revised
Pathway Exposure Report Draft Endangerment Assessment" as partial fulfillment of the reporting
requirements for work assignment 073, Tutu Well Field Site, St. Thomas, U.S. Virgin Islands.
If you have any questions concerning this submittal, please call me or Sally Odland at (212) 393-9634.
Sincerely,
CDM FEDERAL PROGRAMS CORPORATION
Robert D. Goltz, P.E.
ARCS Program Manager
cc: 
C. Kwan, EPA
M. Maddaloni, EPA
S. Odland, CDM Federal, NYC
P. Boyle, CDM Federal, NJ
J. Naugle, CDM Federal, NJ
Document Control (2 copies)
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07 
0833
111 Fulton Street, Suite 710 New York, NY 10038 212 393-9634
Printed on Recycled Paper
*64944*
64944
REVISED PATHWAY EXPOSURE REPORT
DRAFT ENDANGERMENT ASSESSMENT
TUTU WELLS SITE
ST. THOMAS, VIRGIN ISLANDS
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Waste Programs Enforcement
Washington, D.C. 20460
EPA Work Assignment No.
EPA Region
Site No.
Contract No.
CDM Federal Programs Corporation
Document No.
Prepared By
Work Assignment Project Manager
Telephone Number
EPA Work Assignment Manager
Telephone Number
Date Prepared
073-2P1D
II
VID982272569
68-W9-0024
7720-073-LR-BZQY
CDM Federal Programs Corporation
Sally Odland
(212) 393-9634
Caroline Kwan
(212) 264-0151
July 8, 1994
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0834
TABLE OF CONTENTS
BASELINE HUMAN HEALTH RISK ASSESSMENT
Page
1.0 
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2.0 
MEDIA TO BE EVALUATED AND TREATMENT OF DATA . . . . . . . . . . . 4
2.1 
Media to be Evaluated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1.1 Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1.2 Groundwater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 
Treatment of Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.0 
EXPOSURE PATHWAY ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
i
3.1 
Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.2 
Groundwater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.0 
DOSE/RESPONSE PARAMETERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.1 
Noncarcinogenic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.1.1 Definition and Derivation of Reference Doses . . . . . . . . . . . . . 25
4.1.2 RfDs for Detected Chemical Contaminants . . . . . . . . . . . . . . . 26
4.2 
Carcinogenic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.2.1 Definition and Derivation of Slope Factors . . . . . . . . . . . . . . . 26
4.2.2 Slope Factors for Detected Chemical Contaminants . . . . . . . . . . 27
5.0 
RISK CHARACTERIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.0 
UNCERTAINTIES IN RISK ASSESSMENT . . . . . . . . . . . . . . . . . . . . . . . 29
7.0 
PRELIMINARY REMEDIATION GOALS (PRGs) . . . . . . . . . . . . . . . . . . . 30
8.0 
SUMMARY OF THE BASELINE RISK ASSESSMENT . . . . . . . . . . . . . . . 31
ECOLOGICAL RISK ASSESSMENT
TUT
TABLES
Table 1 
List of Wells and Analytical Parameters for the Second Quarterly Sampling
Event - February 1991
Table 2 
List of Wells and Analytical Parameters for the Third Sampling Event - June
1991
Table 3 
List of Wells and Analytical Parameters for the Fourth Sampling Event -
October 1991
Table 4 
List of Sample Locations and Analytical Parameters for the Fifth Sampling
Event - February 1992
Table 5 
List of Sample Locations and Analytical Parameters for the Sixth Sampling
Event - May 1992
Table 6 
List of Sample Locations and Analytical Parameters for the Seventh Sampling
Event - September 1992
Table 7 
List of Sample Locations and Analytical Parameters for the Eigth Sampling
Event - March/April 1993
Table 8 
Potential Exposure Pathways
Table 9 
Variables for Chronic and Subchronic Daily Intake Calculations
FIGURES
Figure 1 
Virgin Islands Site Map
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007
1.0 INTRODUCTION
Under the Technical Enforcement Support (TES) V contract, CDM Federal Programs
Corporation (CDM Federal) received a work assignment (WA) from the U.S. Environmental
Protection Agency (EPA) Region II (Contract No. 68-W9-0002, WA No. C02116) to provide
technical oversight for the EPA by conducting an endangerment assessment to characterize site
risk as part of a Remedial Investigation/Feasibility Study (RI/FS) at the Tutu Wells site in St.
Thomas, Virgin Islands. A work plan for this assignment was submitted to EPA on December
11, 1992.
Task 7 of the work plan requires the preparation and submittal to EPA of a Pathway Exposure
Report, specif "ing the approach which will be used to evaluate the potential human health and
environmental impacts associated with the site. The following major issues will be discussed
in this report:
Baseline Human Health Risk Assessment
• 
Media to be evaluated and treatment of data (quantitative and qualitative)
%
• 
Exposure routes (i.e., groundwater ingestion, dermal contact with soils)
• 
Exposure scenarios (i.e., worker, resident, present/future)
• 
Dose/response parameters
• 
Human health risk characterization
• 
Uncertainties in risk assessment
• 
Preliminary remediation goals (PRGs)
Ecological Risk Assessment
1.1 
Background
The Tutu Wells site is located on the eastern end of St. Thomas at the Anna's Retreat Section
(Figure 1). Most of the wells are used for public drinking water supply. On July 16, 1987, the
EPA received a request from the Department of Planning and Natural Resources (DPNR) in St.
Thomas, for the sampling and analyses of several wells in Tutu, after the DPNR had received
a report regarding an odor emanating from the raw well water on a private property located at
Anna's Retreat, St. Thomas, Virgin Islands.
TUT 
007 
O837
05*00'
10*25'
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te*u
05"06'
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/ /Qrool
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00
GERAGHTY
& MILLER, INC.
Environmental Services
SCALE: SHOWN
SITE LOCATION
TUTU SERVICE STAtlON INVESTIGATION
ST. THOMAS, U.S. VIRGIN ISLANDS
FIGURE
1
Source: Technical Memorandum II - Results of the Field Program - Tutu Service Station Investigation by Geraghty & Miller (May 1993).
On July 21, the EPA and its Technical Assistance Team (TAT) contractor, Roy F. Weston, Inc.,
mobilized to St. Thomas, to perform sampling on the drinking water wells suspected of being
contaminated. These wells were also reported to have a strong, unpleasant odor and were found
to be contaminated with hazardous substances and petroleum products coming from two gas
stations in the Tutu area.
The EPA and TAT, in coordination with DPNR, initiated sampling of wells in the affected area
in July 1987. The test results showed the presence of high concentrations of gasoline and
chlorinated organic compounds. Four wells, Eglin, Four Winds, Harthman, and VIHA, were
closed down by order of DPNR due to high volatile organic compound (VOC) concentrations.
Several of the wells in this area are major commercial well services used for public drinking
water supply; therefore, the incident was classified as major, and the DPNR Commissioner
requested the EPA to assume the role of lead agency.
A testing program of wells located outside of the known area of contamination was conducted
to evaluate possible alternate water supply sources for those areas.
Sampling of cisterns served by the contaminated wells was also performed. EPA directed the
Emergency Response Cleanup Services contractor (ERCS) to: clean and disinfect the five (5)
cisterns that had tested positive for tetrachloroethene (PCE), modify the existing home plumbing,
disconnect the contaminated wells, and dispose of the contaminated water. At EPA's direction,
ERCS also contracted a local water hauler to deliver uncontaminated drinking water to the
cisterns by tank truck. A well sampling program was established by the EPA to monitor the
wells at the Tutu Wells site.
EPA issued a Unilateral Administrative Order to Esso Standard Oil Company, Texaco
Caribbean, Inc., and O'Henry Cleaners on March 22, 1990, to conduct groundwater monitoring
of the drinking water wells in the Tutu aquifer, and to provide water to affected homes until the
respondents connected to the water main.
Esso and Texaco entered into a RCRA 7003/9003 Order of Consent with EPA to conduct a
Remedial Investigation/Feasibility Study at the Tutu Wells site in February 1992. The site was
proposed on the NPL in February 1992. Technical Memorandums I and II, submitted to EPA
in April 1992 and May 1993, respectively, present the initial results of the studies of the Esso
and Texaco gas stations and of VOC contamination in supply wells at the site. The PRP
Technical Committee requested a more complete RI of the site be conducted, and, in December
1993, a Phase U RI work plan was submitted to EPA by Geraghty & Miller, the PRP contractor.
Phase II RI field work is currently in progress.
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083«
2.0 MEDIA TO BE EVALUATED AND TREATMENT OF DATA
Seven quarterly groundwater sampling reports (Geraghty & Miller-February 1991 through
March/April 1993), Technical Memorandum II - Results of the Field Program Tutu Service
Station Investigation (Geraghty & Miller-June 1993), CDM Federal's Data Comparison and
Evaluation Report for Groundwater and Soil Split Samples at the Tutu Wells site (June 1993),
and CDM Federal's September 8 through 15, 1988 and June 5 through 10, 1989 sampling
reports serve as the primary sources of site characterization and analytical data for this
deliverable and the endangerment assessment. As Geraghty & Miller, the PRP contractor, is
currently conducting field sampling activities at the site, additional samples not available at
present will be included in the endangerment assessment per the EPA WAM.
The first quarterly sampling report (Geraghty & Miller-September 1990) results are not being
included in this report or the endangerment assessment as seven more recent quarterly reports
are available.
Monitoring of residential wells at the site has been conducted by Geraghty & Miller since
September 1990. Samples collected during the majority of the sampling events were analyzed
for Target Compound List (TCL) volatile organic compounds (VOCs) only. However, the fifth*
and eighth quarterly sampling events also included analyses for TCL semivolatile organic
compounds (SVOCs) and Target Analyte List (TAL) inorganics and cyanide. The second
quarterly sampling event included, in addition to VOCs, antimony, mercury, selenium, and
thallium analyses. 
As part of Technical Memorandum II, Geraghty & Miller drilled soil
borings, conducted downhole geophysical surveys, installed monitoring wells, took water level
measurements, conducted two aquifer pump tests, and collected soil and groundwater samples.
2.1 
Media to be Evaluated
The environmental media to be quantitatively evaluated in the endangerment assessment include
surface soil, subsurface soil, and groundwater. The following is a summary of specific data sets
for each media for use in the evaluation of potential human health risks and environmental
impacts.
2.1.1 Soil
As part of Technical Memorandum II, seventeen borings, including B-l through B-13, B-13A,
B-14, B-15 and B-16 and eighteen monitoring wells, including MW-1 through MW-10, MW-14,
MW-1D, MW-4D, MW-6D, MW-10D, MW-1 ID, MW-12D, and MW-13D were drilled. Soil
samples were collected from June to August 1992 (see Figures 1-3 and 1-4 of Technical
Memorandum II-June 1993).
Eight surface soil samples, SS-1 through SS-8, were collected from seven locations in August
1992 (See Figure 1-3 of Technical Memorandum II - June 1993). Surface soil samples SS-1,
TUT' 
OO7 
OS4O
SS-2 and SS-8 are considered background samples and were analyzed for TAL metals and
cyanide only. Surface soil samples SS-3 through SS-7 (SS-7 is a duplicate sample of SS-6) were
analyzed for TCL VOCs, 1,2-dibromomethane, n-propylbenzene, methyl tertiary butyl ether,
TCL SVOCs, TAL metals and cyanide, and total petroleum hydrocarbons (TPHs). Samples
were collected at intervals ranging from one to seven inches below land surface after removing
the top one inch layer of soil and vegetation.
Overall, thirty-nine samples, including four replicates, were collected from thirty-five soil boring
and monitoring well locations during the Technical Memorandum II investigation. These
samples were analyzed for TCL VOCs, 1,2-dibromomethane, n-propylbenzene, methyl tertiary
butyl ether, TCL SVOCs, TAL metals and cyanide, and TPHs.
Soil samples were collected at depth intervals ranging from zero to sixteen feet. 
Of these,
eighteen soil samples were collected at depths ranging from zero to two feet, while twenty-one
soil samples were collected at depths ranging from two to twelve feet (with the exception of
sample MW-1D which was collected from one to two and one half feet). Of the eighteen soil
samples collected from zero to two feet, only six are considered surface soil samples since
twelve were collected from beneath paved surfaces. Three of the six surface soil samples (B-14,
B-15, and B-16) are considered surface soil samples at present only, since they will likely be
paved over in the near future. Based on this expected activity, these samples will be considered*
subsurface soil samples in the future-use scenario. Surface soil samples collected from zero to
two feet below unpaved surfaces, and subsurface soil samples collected from under paved
surfaces and from two (and one and one half feet - sample MW-1D) to approximately twelve feet
will be used to produce data summary tables and calculate chemical concentration - toxicity
screens and exposure point concentrations. Subsurface soil data down to approximately twelve
feet will be used in the risk assessment, as this is the zone of soils which may be accessed
during any potential excavation activities.
As part of the RI, Geraghty & Miller is currently installing additional monitoring wells at the
site from which soil samples will be collected. These soil results will be incorporated into the
endangerment assessment per direction of the EPA WAM.
CDM Federal collected hand augered surface soil samples at the Tutu Wells site from September
8 through 15, 1988 and from June 5 through 10, 1989. During the September 1988 sampling
event, one surface soil sample (e-01) was collected at O'Henry dry cleaners, two surface soil
samples (eR-07s and eR-08s) were collected at the Ramsay motor company, two surface soil
samples (eC-09s and eC-lOs) were collected at Antilles auto parts, and two surface soil samples
(eTT-14 and eTT-15) were collected at Tillett Gardens. Samples were analyzed for various
combinations of analytes including TCL VOCs, SVOCs, pesticides/PCBs, TAL metals, and
TPHs, and were collected at intervals ranging from zero to twelve inches below land surface.
Two samples collected at the Texaco gas station (eT-02s and eT-02sd) were originally identified
as surface soil samples, however, based on a recent site visit, the Texaco gas station area was
observed to be completely paved. Therefore, these samples will be considered subsurface soil
samples in the endangerment assessment.
TUT 
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During the June 1989 sampling event, three surface soil samples (eO-02-01, eO-02-02, and eO-02-
03) were collected at O'Henry dry cleaners, three surface soil samples (eL-02-Ols, eL-02-02s,
and eL-02-03s) were collected behind the Curriculum Center Building, and one surface soil
sample (eR-02-02s) was collected at the Ramsay motor company. Samples were analyzed for
various analyte combinations including TCL VOCs, SVOCs, pesticides/PCBs, TAL metals, and
TPHs, and were collected at intervals ranging from zero to two feet below land surface.
Split samples were collected by CDM Federal in August 1992 for each of eight surface soil
samples (SS-1 through SS-8) taken by Geraghty & Miller. In July and August 1992, seven
subsurface soil samples were split with Geraghty & Miller including MW-8, MW-6D, MW-9,
B-6, B-l, MW-5 and B-12. These samples were analyzed for TCL VOCs, SVOCs, TAL metals
and cyanide. Subsurface soil samples were also analyzed for methyl tertiary butyl ether, 1,2-
dibromomethane, n-propylbenzene, and TPHs.
2.1.2 Ground water
Geraghty & Miller has been monitoring approximately twenty-five residential and commercial
water supply wells at and in the vicinity of the site since September 1990 and has produced eight
quarterly sampling reports including the most recent March/April 1993 sampling event results.
The seven most recent sampling reports (reports two through eight) will be utilized in the
production of the Tutu Wells site endangerment assessment. In addition to these reports,
Geraghty & Miller has produced the Technical Memorandum II Tutu Service Station
Investigation report which evaluated fourteen monitoring wells located at the site. O'Henry dry
cleaners has independently installed and sampled four monitoring wells for VOCs. These data,
according to the EPA WAM, will be validated by EPA so that they can be incorporated into the
endangerment assessment. Geraghty & Miller is currently installing and sampling additional
monitoring wells at the site. Per the EPA WAM, results from these wells will be incorporated
into the endangerment assessment.
As part of the second quarterly sampling event in February 1991, twenty-three wells were
sampled for TCL VOCs and at least two of the following metals: antimony, mercury, selenium,
and thallium. These wells and explanations for those wells not sampled are presented in Table
1.
As part of the third quarterly sampling event in June 1991, fourteen wells were sampled for TCL
VOCs only. These wells and explanations for those wells not sampled are presented in Table
2.
As part of the fourth quarterly sampling event in October 1991, fourteen wells were sampled for
TCL VOCs only. These wells and explanations for those wells not sampled are presented in
Table 3.
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007 
0842
TABLE 1
List of Wells and Analytical Parameters for the Second Quanerly Sampling
Event February 1991. Tutu Wells Site, St. Thomas. USVI.
Well
Predetermined Anaivtes
Bryan
De'de
Dimitri
Dench
Devcon I
Devcon III
Eglin I
Eglin II
Eelin III
Four Winds Ia
Four Winds II
Gassett
Hartman II
Hartman III
Harvey
LaPlace
Leonard
Matthias
Ramsey
Rodriguez
Smith
Steeie
Tillett
VTHAI"
VTHAIII
VOCs, thallium, mercury
VOCs. antimony, thallium
VOCs, thallium, mercury
VOCs, antimony, thallium
VOCs, antimony, thallium
VOCs, antimony, thallium
VOCs, thallium, mercury
VOCs, antimony, thallium
VOCs, antimony, thallium
VOCs
VOCs. antimony, thallium
VOCs, thallium, mercury
VOCs, antimony, thallium
VOCs, antimony, thallium
VOCs, antimony, thallium
VOCs, thallium, mercury
VOCs, antimony, thallium
VOCs, thallium, mercury
VOCs, thallium, mercury
VOCs, antimony, thallium
VOCs, antimony, thallium, selenium
VOCs, antimony, thallium
VOCs, thallium, mercury
VOCs, thallium, mercury
VOCs, antimony, thallium
a Four Winds I not sampled due to inoperable pump,
b VTHA I not sampled due to inoperable pump.
Source: Geraghty & Miller Second Quarterly Sampling Report (February 1991).
TIT
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0843
TABLE 2
List of Wells and Analytical Parameters for the Third Sampling Event, June
1991, Tutu Wells Site. St. Thomas. U.S. Virgin Islands.
Well 
Proposed Analytes
Eeiin I 
VOCs
Ealin II 
VOCs
Eeiin III 
VOCs
Four Winds I 
VOCs
Gassett 
VOCs
Hartman II 
VOCs
Hanman III 
VOCs
Harvev 
VOCs
LaPlace 
VOCs
Matthias 
VOCs
Ramsay 
VOCs
Smith 
VOCs
Steeie 
VOCs
Tillett 
VOCs
VOCs Volatile organic compounds.
Analysis will be performed using modified USEPA Method 524.2.
Four Winds II and VTHA I were not sampled due to inoperable pumps.
Source: Geraghty & Miller Third Quarterly Sampling Report (June 1991).
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0844
TABLE 3
List of Wells and Analytical Parameters for the Founh Sampling Event. October
1991. Tutu Wells Site. St. Thomas. U.S. Virgin Islands.
•Veil 
Proposed Anaiytes
Ealin I 
TCL VOCs
E2iin II 
TCL VOCs
Eglin III 
TCL VOCs
Four Winds I 
TCL VOCs
Four Winds II 
TCL VOCs
Gassett 
TCL VOCs
Hartman II 
TCL VOCs
Hanman III 
TCL VOCs
Harvey 
TCL VOCs
LaPlace 
TCL VOCs
Matthias 
TCL VOCs
Ramsay 
TCL VOCs
Smith 
TCL VOCs
Steeie 
TCL VOCs
Tillett 
TCL VOCs
VOCs Volatile organic compounds.
Analysis was performed using modified USEPA Method 524.2.
Four Winds II and VIHA I were not sampled due to inoperable pumps.
Source: Geraghty & Miller Fourth Quarterly Sampling Report (October 1991).
TUT 
007 
0845
As part of the fifth quarterly sampling event in February 1992, eighteen wells were sampled for
TCL VOCs and SVOCs, TAL metals, and cyanide. A Water and Power Authority (WAPA)
sample was collected from the standpipe at the Virgin Island Housing Authority property. The
wells sampled and explanations for those wells not sampled are presented in Table 4.
As part of the sixth quarterly sampling event in May 1992, ten wells were sampled for TCL
VOCs only. These wells are presented in Table 5.
As part of the seventh quarterly sampling event in September 1992, thirteen wells were sampled
for TCL VOCs only. These wells are presented in Table 6.
As part of the eighth quarterly sampling event in March and April 1993, fifteen wells were
sampled for TCL VOCs and SVOCs, TAL metals, and cyanide. A field replicate was collected
from the Harvey well and analyzed for the same parameters. These wells and explanations for
those wells not sampled are presented in Table 7.
As part of the Technical Memorandum II Tutu Service Station Investigation, Geraghty & Miller
installed twelve shallow monitoring wells (MW-1, MW-2, MW-3, MW-4, MW-5, MW-6R,
MW-7, MW-8, MW-9, MW-9S, MW-10, and MW-14) and seven deep monitoring wells (MW-
1D, MW-4D, MW-6D, MW-10D, MW-1 ID, MW-12D, and MW-13D).
Groundwater samples were collected from all shallow and deep wells in September and October
1992 and were analyzed for TCL VOCs and SVOCs, metals, cyanide, 1,2-dibromomethane, n-
propylbenzene, methyl tertiary butyl ether, and TPHs.
CDM Federal collected split samples in September and October 1992 of five Geraghty & Miller
aqueous samples (four ground water samples and one field blank). The ground water samples
(MW-6R, MW-4, MW-5, and MW-14) were analyzed for TCL VOCs and SVOCs, TAL metals
(total and dissolved), cyanide, methyl tertiary butyl ether, 1,2-dibromomethane, n-
propylbenzene, and TPHs.
Groundwater results from each of the wells from each sampling round, including split samples,
as appropriate, will be used to produce a data summary table and to calculate a chemical
concentration-toxicity screen and exposure point concentrations. Upgradient supply wells T3
and T4 (VIHA III and VIHA IV (alternate)) will not be included in the calculation of risk/health
effects nor will the cross gradient wells A, C, L, and M (Bryan, Demitri, Leonard, and
Lockhart (alternate)) which are impacted by pumping only in the residential area in the
immediate vicinity and not by the site. Supply wells B, D, El, E2, E3 (Dede, Dench, Devcon
I, Devcon II (alternate) and Devcon III) are clean wells downgradient of the contaminant plume,
and therefore will not be utilized in quantitative calculations in the endangerment assessment.
Groundwater data may be segregated as shallow and deep, if appropriate, in the exposure
assessment for the evaluation of potential risks/hazards to groundwater.
10
TUT 
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0846
TABLE 4
List of Sample Locations and Analytical Parameters for the Fifth Sampling Event.
February 1992, Tutu Wells Site, St. Thomas, U.S. Virgin Islands.
Samuie ID
Proposed Anaiytes
Dede
Eglin I
Ezlin II
Egiin III
Four Winds I
Four Winds II
Gassett
Hartman II
Hartman III
Harvey
LaPlace
Leonard
Matthias
Ramsay
Rodriguez
Smith
Steeie
Tillett
VIHA I, VIHA H, or VIHA HI
(if possible)
Water and Power Authority (WAPA)
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNA, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs; TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL VOCs, TCL BNAs, TAL Metals, and Cyanide
TCL 
Target compound list.
TAL 
Target analyte list.
VOCs Volatile organic compounds.
VOC analysis was performed using modified USEPA Method 524.2.
BNAs Base neutral and acid extractable compounds.
VIHA I, VIHA II, and VIHA HI were not sampled due to inoperable pumps.
The WAPA sample was collected from the standpipe at the VIHA property located on Route 38 in Tutu.
Source: Geraghty & Miller Fifth Quarterly Sampling Report (February 1992).
11
TUT
007 
OB47
TABLE 5
List of Sample Locations and Analytical Parameters for the Sixth Sampling Event,
May 1992, Tutu Wells Site, St. Thomas, U.S. Virgin Islands.
Sample ID 
Proposed Analytes
Eglin I 
TCL VOCs
Eglin H 
TCL VOCs
Eglin m 
TCL VOCs
Gassett 
TCL VOCs
Harvey 
TCL VOCs
LaPlace 
TCL VOCs
Ramsay 
TCL VOCs
Smith 
TCL VOCs
Steele 
TCL VOCs
Tillett 
TCL VOCs
TCL 
Target compound list.
VOCs Volatile organic compounds.
VOC analysis was performed using modified USEPA Method 524.2, Revision 3.0 (USEPA
1989).
Source: Geraghty & Miller Sixth Quarterly Sampling Report (May 1992).
TUT 
OO7 
O84S
TABLE 6
List of Sample Locations and Analytical Parameters for the Seventh Sampling
Event. September 1992, Tutu Wells Site, St. Thomas, U.S. Virgin Islands.
Sample ID 
Proposed Analytes
E§lin I 
TCL VOCs
E§lin II 
TCL VOCs
Eglin III 
TCL VOCs
Four Winds I 
TCL VOCs
Four Winds II 
TCL VOCs
Gassett 
TCL VOCs
Harthman II 
TCL VOCs
Harvey 
TCL VOCs
LaPlace 
TCL VOCs
Ramsay 
TCL VOCs
Smith 
TCL VOCs
Steeie 
TCL VOCs
Tille« 
TCL VOCs
TCL 
Target compound list.
VOCs Volatile organic compounds.
VOC analysis was performed using modified USEPA Method 524.2, Revision 3.0 (USEPA
1989).
Source: Geraghty & Miller Seventh Quarterly Sampling Report (September 1992).
13
TUT 
007 
0849
TABLE 7
List of Sample Locations and Analytical Parameters for the Eighth Sampling Event. March/ Apnl 1993,
Tutu Wells Site, St. Thomas, U.S. Virgin Islands.
Sample ID
Analytes
Dede
Dench
Devcon II
Eglin I
Eglin III
Four Winds I
Gassett
Harvey
Harvey FR
LaPlace
Leonard
Ramsay
Rodriguez
Smith
Steeie
Tillett
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
VOCs,
VOCs,
VOCs,
VOCs,
VOCs,
VOCs,
VOCs,
VOCs,
VOCs,
VOCs,
VOCs,
VOCs.
VOCs,
VOCs,
TCL VOCs,
TCL VOCs,
TCL BNAs,
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
TCL
BNAs,
BNAs,
BNAs,
BNAs,
BNAs,
BNAs,
BNAs,
BNAs,
BNAs,
BNAs,
BNAs,
BNAs,
BNAs,
BNAs,
BNAs,
TAL
TAL
TAL
TAL
Metals,
Metals,
Metals,
Metals,
TAL Metals,
TAL
TAL
TAL
TAL
TAL
TAL
TAL
TAL
TAL
TAL
TAL
Metals,
Metals,
Metals,
Metals,
Metals,
Metals,
Metals,
Metals,
Metals,
Metals,
Metals,
and
and
and
and
and
and
and
and
and
and
and
and
and
and
and
and
Cyanide
Cyanide
Cyanide
Cyanide
Cyanide
Cyanide
Cyanide
Cyanide
Cyanide
Cyanide
Cyanide
Cyanide
Cyanide
Cyanide
Cyanide
Cyanide
TCL 
Target compound list.
TAL 
Target analyte list.
VOCs 
Volatile organic compounds.
BNAs 
Base neutral and acid extractable compounds.
VOC analysis was performed using Modified USEPA Method 524.2.
The VIHA I, VIHA II, Eglin II, Four Winds II, and Devcon III wells were not sampled due to inoperable pumps.
The Matthias well was not sampled because the property owner did not allow access.
The Harthman II and Harthman III wells were not sampled because of construction activities in the new Tutu
Shopping Plaza site.
Source: Geraghty & Miller Eighth Quarterly Sampling Report (March/April 1993).
14
TUT 
OO7 
O850
2.2 
Treatment of Data
A summary of detected chemicals in each of the site media will be presented in tabular form in
the risk assessment. The table will include, for each detected chemical, the frequency of
detection, the range of detected concentrations, the location of the maximum detected
concentration, and the range of non-detect concentrations The frequency of detection will be
reported as the number of detects divided by the number of analyzed samples. CDM Federal
split sample results will be compared to the PRP results. If the results are similar, they will be
averaged and this averaged value will be used in the risk assessment calculations. If the results
are not similar, the higher value will be used for conservatism in the risk assessment
calculations. Each groundwater sample collected from multilevel wells and from multiple
sampling rounds will be considered as an individual sample. Blanks, including field, trip, and
laboratory, and rejected data (i.e., qualified with "R") will not be included in the frequency tally
or range of concentrations. All other data qualifiers will be evaluated for inclusion in the risk
assessment.
The maximum concentration of chemicals detected in each of the media and their oral toxicity
values (i.e., reference dose and slope factor) will be used in the chemical concentration - toxicity
screens. These screens, along with other criteria, will be utilized in the selection of chemicals
of potential concern.
15
TUT 
OO7 0851
3.0 EXPOSURE PATHWAY ANALYSIS
The objective of this section is to present a preliminary analysis of potential exposure pathways
to be evaluated in the human health risk assessment. An exposure pathway describes the
transport of a chemical from the source of release to the exposed individual. An exposure
pathway links the sources, locations, and types of environmental patterns to determine significant
pathways of human exposure. As defined in EPA's Risk Assessment Guidance for Superfund
(RAGS), an exposure pathway consists of four elements:
• 
Source and mechanism of chemical release
• 
Release or transport mechanism
• 
Point of potential human contact (exposure point)
• 
Exposure route at the contact point
The potential present and future exposure pathways considered for evaluation in the Tillett
Gardens, Curriculum Center Building, Fire Department/Texaco gas station/Antilles auto
parts/Ramsay motor company, Esso gas station/Splash and Dash car wash, and O'Henry dry
cleaners/Liquor Barn areas of concern at the Tutu Wells site are presented in Table 8. Table
9 presents the exposure variables to be used in the daily intake calculations. An exposure point
concentration will be developed for each chemical of potential concern in each medium for use
in the calculation of daily intakes. 
This concentration does not reflect the maximum
concentration that could be contacted at any one time, but is considered a reasonable estimate
of the concentration likely to be contacted over time as long-term contact with the maximum
concentration is not a reasonable assumption.
Due to the uncertainty associated with any estimate of exposure concentration, the 95 percent
upper confidence limit (UCL) on the arithmetic mean is used for this variable. If there is a large
variability in measured concentrations, the 95 percent UCL may exceed the maximum measured
or modeled values in which case the maximum detected or modeled value is used. The formula
used to calculate the 95 percent UCL will depend on whether the site data are normally or
lognormally distributed.
3.1 
Soil
Surficial soil may be contaminated by direct spillage or from surface runoff. Subsurface soil
may be contaminated as a result of leaching and downward migration of mobile contaminants.
Soil contamination will be evaluated for resident, site worker, and construction worker exposures
under present and/or future-use conditions as presented in Table 8. The ingestion, dermal
contact, and inhalation routes of exposure have been considered. Justifications for the inclusion
16
TUT 
O07 
OS52
6/23/94
EXP-PWAY.XLS
TABL 
J
TUTU WELLS SITE
POTENTIAL EXPOSURE PATHWAYS
Matrix
Receptor
Population^)
Exposure 
Retained for
Route(s)______Quantitative Analysis
Justification
PRESENT - USE SCENARIOS:
Surface Soil
Site Residents
(Adults and Children)
(TOett Gardens Area)
Site Workers
1 - (Employees of the Curriculum
Center Building)
2- (Employees of the Fire Dept,
Texaco gas station, Antilles
auto parts, and Ramsay motor
company)
3- (Employees of the Esso gas
station and the Splash and
Dash car wash)
4- (Employees of O'Henry dry
cleaners and Liquor Bam)
Construction Workers
(Site-wide)
digestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs"
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs"
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs"
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs"
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs
Yes
Yes
No
Yes
Yes
Yes
No
Yes
Yes
Yes
No
Yes
No
No
No
No
Yes
Yes
No
Yes
No
No
No
No
Site residents are expected to come into direct contact with
surface soil in the vicinity of their home and Tillett Gardens and
Art Center. The inhalation of participates from surface soil is
assumed to be negligible, as the areas where samples were
collected either consist of hard packed soil or are covered by
vegetation.
Site workers may come into direct contact with surface soil
during the course of a normal work day (i.e., outdoor work, lunch
hour). The inhalation of participates from surface soil is assumed
to be negligible, as the areas where samples were collected
consist of either hard packed soil or are covered to a large extent
by vegetation.
Site workers may come into direct contact with surface soil
during the course of a normal work day (i.e., outdoor work, lunch
hour). The inhalation of particulates from surface soil is assumed
to be negligible, as the areas where samples were collected
consist of either hard packed soil or are covered to a large extent
by vegetation.
Since the Esso gas station and Splash and Dash car wash
properties are completely paved, no surface soil is available for
contact. Therefore, no surface soil exposure can occur.
Site workers may come into direct contact with surface soil
during the course of a normal work day (i.e., outdoor work, lunch
hour). The inhalation of particulates from surface soil is assumed
to be negligible, as the area where samples were collected
is covered to a large extent by dense vegetation.
No construction work is currently in progress in any areas of
concern at the site.
CO
en
6/23/94
EXP-PWAY.XLS>
TAB 
)
TUTU WELLS SITE
POTENTIAL EXPOSURE PATHWAYS
Matrix
Receptor
Population(s)
PRESENT - USE SCENARIOS CONTD:
Subsurface Soil
Groundwater
_j
t —
•H
O
O
Nl
o
"TJ
tfl
Site Residents
(Adults and Children)
fjyiett Gardens Area)
Site Workers
1 - (Employees of the Curriculum
Center Building)
2- (Employees of the Fire Dept.,
Texaco gas station, Antilles
auto parts, and Ramsay motor
company)
3- (Employees of the Esso gas
station and the Splash and
Dash car wash)
4- (Employees of O'Henry dry
cleaners and Liquor Bam)
Construction Workers
(Site-wide)
Site Residents
(Adults and Children)
Site Workers
(AH)
Construction Workers
(Site-wide)
Exposure 
Retained for
Route(s) 
Quantitative Analysis 
Justification
Ingestion
Dermal Contact*
Inhalation of Partculates
Inhalation of VOCs
Ingestion
Dermal Contact*
Inhalation of Partculates
Inhalation of VOCs
Ingestion
Dermal Contact*
Inhalation of Partculates
Inhalation of VOCs
Ingestion
Dermal Contact*
Inhalation of Partculates
Inhalation of VOCs
Ingestion
Dermal Contact*
Inhalation of Partculates
Inhalation of VOCs
Ingestion
Dermal Contact*
Inhalation of Partculates
Ingestion
Dermal Contact (Shower)
Inhalation of VOCs (Shower)
Ingestion
Dermal Contact (Shower)
Inhalation of VOCs (Shower)
Ingestion
Dermal Contact (Shower)
Inhalation of VOCs (Shower)
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
No
No
No ,
No
No
No construction work (i.e., excavation activity) is currently in
progress in this area of the site.
No construction work (i.e., excavation activity) is currently in
progress in this area of the site.
No construction work (i.e., excavation activity) is currently in
progress in this area of the site.
No construction work (i.e., excavation activity) is currently in
progress in this area of the site.
No construction work (i.e., excavation activity) is currently in
progress in this area of the site.
No construction work (i.e., excavation activity) is currently in
progress in any areas of concern at the site.
Currently, an order against drinking and bathing in groundwater
at the site has been issued. However, since evidence of
pumping exists at the Ramsay well, residents may be using the
groundwater for these purposes in addition to secondary
purposes such as clothes washing, lawn watering, etc.
Currently, an order against drinking and bathing in groundwater
at the site has been issued. However, since evidence of
pumping exists at the Ramsay well, site workers may be using
the groundwater for drinking. Site workers are not expected to
shower on-site.
No construction work (i.e., excavation activity) is currently in
progress in any areas of concern at the site.
6/23/94
EXP-PWAY.XLb
TAB 
)
TUTU WELLS SITE
POTENTIAL EXPOSURE PATHWAYS
Matrix
FUTURE - USE SCENARIOS:
Surface Soil
Receptor
Population(s)
Exposure
Route(s)
Retained for
Quantitative Analysis
Justification
Residents
(Adults and Children)
(Tiltett Gardens Area)
Site Workers
1 - (Employees of the Curriculum
Center Building)
2- (Employees of the Fire Dept.,
Texaco gas station, Antilles
auto parts, and Ramsay motor
company)
3- (Employees of the Esso gas
station and the Splash and
Dash car wash)
Ingestion
Dermal Contact*
Inhalation of Partculates
Inhalation of VOCs"
Ingestion
Dermal Contact*
Inhalation of Partculates
Inhalation of VOCs"
Ingestion
Dermal Contact*
Inhalation of Partculates
Inhalation of VOCs"
Ingestion
Dermal Contact*
Inhalation of Partculates
Inhalation of VOCs
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Site residents are expected to come into direct contact with
surface soil in the vicinity of their home and Tillett Gardens and
Art Center. The inhalation of partculates exposure route may be
of concern due to the potential for future construction work
(i.e., excavation activity) in this area.
Site workers may come into direct contact with surface soil
during the course of a normal work day (i.e., outdoor work, lunch
hour). The inhalation of particulates exposure route may be of
concern due to the potential for future construction work
(i.e., excavation activity) in this area.
Site workers may come into direct contact with surface soil
during the course of a normal work day (i.e., outdoor work, lunch
hour). The inhalation of particulates exposure route may be of
concern due to the potential for future construction work
(i.e., excavation activity) in this area.
Since the Esso gas station and Splash and Dash car wash
properties are completely paved, no surface soil would be
available for contact. Therefore, no surface soil exposure can
occur.
H
4- (Employees of O'Henry dry
cleaners and Liquor Bam)
Construction Workers
(Exposure to be evaluated for
the most chemically contam-
inated area of concern at the
site - to be determined)
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs"
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs"
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Site workers may come into direct contact with surface soil
during the course of a normal work day (i.e., outdoor work, lunch
hour). The inhalation of particulates exposure route may be of
concern due to the potential for future construction work
(i.e., excavation activity) in this area.
The potential exists for future commercial development of the
areas of concern at the site. The area of concern selected for
evaluation will depend on the chemical concentrations detected,
toxicity, and the calculated residential risks.
O
00
r-ft
6/23/94
EXP-PWAY.XLS
TABk 
)
TUTU WELLS SITE
POTENTIAL EXPOSURE PATHWAYS
Matrix
Receptor
Population(s)
Exposure 
Retained for
Route(8)______Quantitative Analysis
Justification
FUTURE - USE SCENARIOS CONT'D:
Subsurface Soil
Residents
(Adults and Children)
(Tillett Gardens Area)
Site Workers
1- (Employees of the Curriculum
Center Building)
2- (Employees of the Fire Dept.,
Texaco gas station, Antilles
auto parts, and Ramsay motor
company)
3- (Employees of the Esso gas
station and the Splash and
Dash car wash)
4- (Employees of O'Henry dry
cleaners and Liquor Bam)
Construction Workers
(Exposure to be evaluated for
the most chemically contam-
inated area of concern at the
site - to be determined)
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs"
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs"
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs**
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs**
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs"
Ingestion
Dermal Contact*
Inhalation of Particulates
Inhalation of VOCs**
No
Yes
Yes
Yes
No
Yes
Yes
Yes
No
Yes
Yes
Yes
No
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
During potential future construction work (i.e., excavation
activity), residents may come into direct contact with exposed
subsurface soil. However, they are assumed to ingest a
negligible amount of excavated subsurface soil.
During potential future construction work (i.e., excavation
activity), site workers may come into direct contact with exposed
subsurface soil. However, they are assumed to ingest a
negligible amount of excavated subsurface soil.
During potential future construction work (i.e., excavation
activity), site workers may come into direct contact with exposed
subsurface soil. However, they are assumed to ingest a
negligible amount of excavated subsurface soil.
During potential future construction work (i.e., excavation
activity), site workers may come into direct contact with exposed
subsurface soil. However, they are assumed to ingest a
negligible amount of excavated subsurface soil.
During potential future construction work (i.e., excavation
activity), site workers may come into direct contact with exposed
subsurface soil. However, they are assumed to ingest a
negligible amount of excavated subsurface soil.
The potential exists for future commercial development of the
areas of concern at the site. The inhalation routes of exposure
may be of concern based on the fact that construction workers
would routinely come into direct contact with soil during invasive
activities. The area of concern selected for evaluation will depend
on the chemical concentrations detected, toxicity, and the
calculated residential risks.
Groundwater
o
•-4
Site Residents
(Adults and Children)
Ingestion
Dermal Contact (Shower)
Inhalation of VOCs(Shower)
Yes
Yes
Yes
Currently, an order against drinking and bathing in groundwater
at the site has been issued. However, since evidence of pump-
ing exists at the Ramsay well, residents may continue to use
the groundwater in the future for these purposes in addition to
secondary purposes such as clothes washing, lawn watering,
u~
6/23/94
EXP-PWAY.XLS
TABl 
/
TUTU WELLS SITE
POTENTIAL EXPOSURE PATHWAYS
Matrix
Receptor
Population(s)
Exposure 
Retained for
Routes)______Quantitative Analysis
Justification
FUTURE - USE SCENARIOS CONT'D:
Groundwater
Site Workers
(AH)
Construction Workers
Ingestion 
Yes
Dermal Contact (Shower) 
No
Inhalation of VOCs (Shower) 
No
Ingestion 
Yes
Dermal Contact (Shower) 
No
Inhalation of VOCs (Shower) 
No
Currently, an order against drinking and bathing in groundwater
at the site has been issued. However, since evidence of pump-
ing exists at the Ramsay well, site workers may continue to use
the groundwater in the future for drinking. Site workers are not
expected to shower on-site.
Currently, an order against drinking and bathing in groundwater
at the site has been issued. However, since evidence of pump-
ing exists at the Ramsay well, construction workers may continue
to use the groundwater in the future for drinking. Construction
workers are not expected to shower on-site.
• The dermal contact pathway can only be quantitatively evaluated for PCBs, dioxin, and cadmium as only these chemicals have established dermal
absorption factors (PCBs » 6%, dioxin - 3%, and cadmium - 1%). All other chemicals will be qualitatively discussed.
** The inhalation of VOCs pathway will be evaluated for retention in or elimination from the risk assessment based on the results of the chemical concentration-toxicity screens performed
for site soils in the various areas of concern and the chemicals of potential concern selected. The results of the screens and the chemicals of potential concern selected
for further evaluation will be discussed with the USEPA Risk Assessment Specialist before the pathway is retained for or eliminated from quantitative analysis.
O
CO
6/23*4
EXPVAH1.XLS
TUTU WELLS SITE
VARIABLES USED FOR CHRONIC AND SUBCHRONIC DAILY INTAKE CALCULATIONS
Matrices and
Receptor Populations
Surfac* Soil
Residents
(Tiltett Gardens Area)
Adults
Children (0-6 years)
Adults
Children (0-6 years)
Adults
Children (0-6 years)
Adults
Children (0-6 years)
Site Workers
Adults
Construction Workers
Adults
Subsurface Soil
Residents
(Tiltett Gardens Area)
Adults
Children (0-6 years)
Adults
Children (0-6 years)
Adults
Children (0-6 years)
Site Workers
Adults
Construction Workers
Adults
Exposure
Route
Ingesbon
Ingestion
Dermal Contact
Dermal Contact
Inhalation of Particulates
Inhalation of Particulates
Inhalation of VOCs
Inhalation of VOCs
Ingesbon
Dermal Contact
Inhalation of Particulates
Inhalation of VOCs
Ingesfon
Dermal Contact
Inhalation of Particulates
Inhalation of VOCs
Dermal Contact
Dermal Contact
Inhalation of Particulates
Inhalation of Particulates
Inhalation of VOCs
Inhalation of VOCs
Dermal Contact
Inhalation of Particulates
Inhalation of VOCs
Ingestion
Dermal Contact
Inhalation of Particulates
Inhalation of VOCs
CONCENTRATIONS
CW CA/SSC 
CS 
VF
(mo/I) (mg/m3) (mo/kg) (m3/kg)
Rl Data
RIData
RIData
RIData
0.070 
RIData
0.070 
Rl Data
RIData 
(4)
RIData 
(4)
RIData
RIData
0.070 
RIData
RIData 
(4)
Rl Data
RIData
0.070 
RIData
RIData 
(4)
RIData
RIData
0.070 
RIData
0.070 
RIData
RIData 
(4)
RIData 
(4)
RIData
0.070 
RIData
RIData 
(4)
Rl Data
RIData
0.070 
Rl Data
RIData 
(4)
CONTACT PARAMETERS
SA 
PC 
IR(1) 
RF 
AF 
ABS 
Fl
(cm2) (cm/hr) (variable) (unitless) (ma/cm2) (unitless) (unitless)
100mg/day 
- 
- 
- 
1
200moyday 
- 
- 
- 
1
5065 
- 
- 
1 
(5)
1270 
- 
1 
(5)
0.83m3/hr 
0.75
0.83m3/hr 
0.75
0.83m3/hr .
.
.
.
083m3/hr .
.
.
.
50mg/day 
1
1940 
- 
- 
1 
(5) 
-
0.83m3/hr 
0.75
0.83m3/hr 
.
.
.
.
480 mo/day 
1
6125 
- 
- 
1 
(5) 
-
0.83m3/hr 
0.75
0.83m3/hr .
.
.
.
5065 
- 
1 
(5)
1270 
- 
- 
1 
(5)
0.83m3/hr 
0.75
0.83m3/hr 0.75
0.83m3/hr 
- 
- 
- 
-
0.83m3/hr 
.
.
.
.
1940 
- 
- 
1 
(5)
0.83m3/hr 0.75 
- 
-
0.83m3/hr 
.
.
.
.
480mg/day 
- 
- 
- 
1
6125 
- 
- 
-. , ' ' 1 
(5)
0.83m3/hr 
0.75
0.83m3/hr 
- 
-
TIME VARIABLES
ET 
EF 
ED AT (2)
(hr/day) 
(day/yr) 
(yrs) (years)
350 
24 70(24)
350 
6 70(6)
350events/yr 24 70(24)
350events/yr 
6 70(6)
18 
350 
24 70(24)
18 
350 
6 70(6)
18 
350 
24 70(24)
18 
350 
6 70(6)
250 
25 70(25)
250events/yr 25 70(25)
8 
250 
25 70(25)
8 
250 
25 70(25)
225 
1 70(1)
225events/yr 
1 70(1)
8 
225 
1 70(1)
8 
225 
1 70(1)
91events/yr 
1 70(1)
91 events/yr 
1 70(1)
18 
91 
1 70(1)
18 
91 
1 70(1)
18 
91 
1 70(1)
18 
91 
1 70(1)
65 events/yr 
1 70(1)
8 
65 
1 70(1)
8 
65 
1 70(1)
65 
1 70(1)
65 events/yr 
1 70(1)
8 
65 
1 70(1)
8 
65 
1 70(1)
CF(3)
(variable)
lE-6kg/mg
1E-6kg/mg
1 E-6 kg/mg
lE-6kg/mg
lE-6kg/mg
lE-6kg/mg
.
-
1E-6kg/mg
lE-6kg/mg
lE-6kg/mg
-
1 E-6 kg/mg
lE-6kg/mg
IE-6 kg/mg
-
1 E-6 kg/mg
IE-6 kg/mg
1 E-6 kg/mg
1 E-6 kg/mg
-
-
1 E-6 kg/mg
IE-6 kg/mg
-
1 E-6 kg/mg
1 E-6 kg/mg
1 E-6 kg/mg
"
BW
fa)
70
15
70
15
70
15
70
15
70
70
70
70
70
70
70
70
70
15
70
15
70
15
70
70
70
70
70
70
70
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S/31/94
EXPVAR1.XLS
TABLI
\nt'd.)
TUTU WELLS SITE
VARIABLES USED FOR CHRONIC AND SUBCHRONIC DAILY INTAKE CALCULATIONS
Matrices and
Receptor Populations
Groundwater
Site Residents
Adults
Children (0-6 years)
Adults
Children (0-6 years)
Adults
Children (0-6 years)
Site Workers
Adults
Construction Workers
Adults
Exposure
Route
Ingestion
Ingeston
Dermal Contact (Shower)
Dermal Contact (Shower)
Inhalafon(Shower)
Inhalabon(Shower)
Ingestion
Ingestion
CONCENTRATIONS 
CONTACT PARAMETERS
CW CA/SSC 
CS
(mg/l) (mg/m3) (mg/kg)
Rl Data
Rl Data 
-
Rl Data
Rl Data 
-
(6)
(6)
Rl Data 
-
Rl Data
SA 
PC 
IR(1) RF 
AF 
ABS 
Fl
(cm2) (cm/hr) (variable) (unidess) (mg/cm2) (unitless) (unidess)
2 I/day 
.
.
.
.
2l/day 
.
.
.
.
18150 
(7) 
- 
- 
- 
-
5400 
(7) 
- 
-
0.6m3/hr 
.
.
.
.
0.6m3/hr 
.
.
.
.
1 1/day 
.
.
.
.
1 1/day 
.
.
.
.
TIME VARIABLES
ET 
EF 
ED AT (2)
(hr/day) 
(day/yr) 
(yrs) (years)
350 
30 70(30)
350 
6 70(6)
0.2 
350 
30 70(30)
0.2 
350 
6 70(6)
0.2 
350 
30 70(30)
0.2 
350 
6 70(6)
250 
25 70(25)
225 
1 70(1)
CF(3)
(variable)
-
1E-3l/cm3
lE-3l/cm3
-
-
-
BW
(kq)
70
15
70
15
70
15
70
70
NOTES:
(1) Ingestion or inhalation rate
(2) 70 years for carcinogens, 30 years for noncarcinogens for adult residents. 25 years for noncarcinogens for site workers, 6 years for noncarcinogens for children and 1 year for all subchronic exposures
(multiplied by 365 days).
(3) Conversion Factor
(4) The soil-to-air volatilization factor (VF) will be calculated individually for chemicals of potential concern as appropriate.
(5) Soil and sediment dermal contact absorption factors: 6% = PCBs, and 1% = cadmium.
(6) This value was modeled from Rl Data.
(7) This value is the default value for water when no chemical-specific values were available in USEPA (1992d).
Other Abbreviations:
CW = Contaminant concentration in water
CA ^ Contaminant concentration in air
CS = Contaminant concentration in soil
SA = Skin surface area available for dermal contact
RF = Respirabte fraction of particulates
AF = Soil-to-skin adherence factor
SSC = Suspended soil concentration
Fl = Fraction ingested from contaminant source
ET - Exposure Time
EF = Exposure Frequency
ED = Exposure Duration
BW = Body Weight
AT = Averaging Time
O
00
or exclusion of scenarios from quantitative evaluation have been presented.
Surface soil may currently be contacted by site residents in the Tillett Gardens area and by site
workers in the Curriculum Center Building area, Fire Department/Texaco gas station/Antilles
auto parts/Ramsay motor company, and the O'Henry dry cleaners area. Surface soil may be
contacted in the future by residents, site workers, and/or construction workers. The potential
exists for further residential and/or commercial/industrial development of the site in the future.
Based on this information, the possibility of exposure to potential future residents, site workers,
and/or construction workers have been considered for the ingestion, dermal contact, and
inhalation routes. Justifications for the inclusion or exclusion of scenarios from quantitative
evaluation have been presented.
Subsurface soil could be contacted in the future (Table 8) by residents, site workers, and/or
construction workers. Subsurface soil data collected at depths between two to twelve feet will
be used to determine exposure point concentrations since typical excavation activities would not
exceed this depth. 
The potential exists for further residential and commercial/industrial
development of the site. 
Based on this information, the possibility of exposure to potential
future residents, site workers, and/or construction workers has been considered for the ingestion,
dermal contact, and inhalation routes. Justifications for the inclusion or exclusion of scenarios
from quantitative evaluation have been presented.
Per EPA Region II CERCLA guidance, only cadmium, PCBs, and dioxin may be quantitatively
evaluated for the dermal contact pathway for the soil matrix.
The inhalation of VOCs pathway will be retained as part of or eliminated from the risk assessent
based on the results of the soil chemical concentration-toxicity screens and the selected chemicals
of potential concern. The USEPA Risk Assessment Specialist will be consulted before any
inhalation of VOCs pathway is eliminated from further consideration.
3.2 
Groundwater
Groundwater obtained from wells at the site is currently restricted to secondary uses such as
clothes washing and lawn watering. An order against drinking the groundwater at the site has
been issued and an alternate source of water has been provided to residents and businesses (i.e.,
water is brought in by truck). Although an institutional control on groundwater has been put
into place, it cannot guarantee that residents or businesses are not using and will not use the
groundwater since the wells are not abandoned. Evidence exists which shows that pumping has
occurred recently at the Ramsay well. Therefore, it is reasonable to assume that human
receptors are using the site groundwater at present and may continue to use it in the future for
secondary purposes (clothes washing and lawn watering) and potentially for primary purposes
(drinking and bathing). Based on this, the possibility of exposure to current residents and site
workers via the ingestion, dermal contact, and inhalation routes and future residents, site
workers and construction workers via the ingestion, dermal contact, and inhalation routes have
been considered for quantiative evaluation. Justifications for the inclusion or exclusion of
scenarios from quantiative evaluation have been presented.
Tl JT 
<"><">7 
OS6O
24
4.0 DOSE/RESPONSE PARAMETERS
In the toxicity assessment portion of the risk assessment, the relationship between the potential
level of exposure (dose) and the likelihood and/or severity of adverse effects (response) will be
evaluated. As part of this evaluation, available toxicity values or dose/response parameters for
the chemicals detected at the site will be compiled. These dose/response parameters will be used
in the chemical concentration-toxicity screens and integrated with chemical intake levels derived
in exposure assessment to characterize the level of potential risks and health effects.
Dose/response parameters have been developed by EPA for the evaluation of both
noncarcinogenic and carcinogenic effects of exposure to humans. The oral and inhalation
reference doses (RfDs) are the toxicity values used to evaluate noncarcinogenic effects resulting
from exposure. The oral and inhalation slope factors (SFs) are used to evaluate potential
carcinogenic effects. Oral RfDs and inhalation reference concentrations (RfCs), as well as SFs
derived for oral and inhalation exposures, are available through EPA's on-line Integrated Risk
Information System (IRIS) and Health Effects Assessment Summary Tables (HEAST) Annual
FY-1993 and Supplement Numbers 1. When a value is not available through these sources, the
Superfund Health Technical Support Center will be consulted.
4.1 
Noncarcinogenic Effects
4.1.1 Definition and Derivation of Reference Doses
Toxicity values are available depending on the exposure route (oral or inhalation), the critical
effect, and the length of exposure (subchronic or chronic) to be evaluated. Chronic and
subchronic oral and inhalation RfDs may be used to evaluate noncarcinogenic effects. A chronic
RfD is defined as an estimate of a daily exposure level for the human population, including
sensitive subpopulations, that is likely to be without an appreciable risk of harmful effects during
a lifetime. Chronic RfDs are specifically developed to be protective of long-term exposure to
a chemical, and are defined as exposure periods exceeding seven years (approximately ten
percent of a human lifetime of 70 years). Subchronic RfDs are used to characterize potential
noncarcinogenic effects associated with shorter-term exposure periods between two weeks and
seven years.
RfDs are derived by EPA based on the concept of a threshold. For many noncarcinogenic
effects, protective mechanisms may exist which must be overcome before an adverse effects is
manifested. A range of exposure levels may be tolerated by an organism before an adverse
effect occurs. In the development of the RfDs, human epidemiological and clinical studies, and
experimental animal studies are reviewed to identify the upper-bound of the tolerance range (i.e.,
maximum subthreshold level) which is protective of sensitive individuals in the population. The
no observed adverse effect level (NOAEL) or lowest observed adverse effect level (LOAEL) is
generally used to describe this level and is the basis for the derivation of the RfD. Uncertainty
25
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and modifying factors are then applied to the NOAEL, depending on the quality and the
applicability of the available animal or human toxicity study, as the final step in the derivation
of the RfD. The resultant oral RfD is expressed in terms of unit concentration of a compound
(mg) per unit body weight (kg) per unit time (day) or mg/kg/day.
Inhalation RfCs, expressed in mg/m3, are derived by interim methods adopted by EPA in 1988.
These methods differ slightly from those used for the derivation of RfDs because of (1)
dynamics of the respiratory system and its diversity across species, and (2) differences in
physicochemical properties of contaminants, such as size and shape of a particle. The RfC value
is reported as a concentration in air (mg/m3), although it may be converted to a corresponding
inhaled dose (mg/kg/day) by dividing by 70 kg body weight and multiplying by 20 nWday
inhalation rate.
4.1.2 RfDs for Detected Chemical Contaminants
Chronic and subchronic oral and inhalation RfDs and the uncertainty factors associated with
them will be presented in the risk assessment for all chemicals detected at the site having such
established values.
Only a limited number of inhalation RfDs are available. Those chemicals of potential concern1
having available RfD values will be evaluated via the inhalation route of exposure. Otherwise,
they can only be qualitatively addressed.
4.2 
Carcinogenic Effects
4.2.1 Definition and Derivation of Slope Factors
The carcinogenic slope factor and the accompanying weight-of-evidence classification are used
to evaluate potential human carcinogenic risks associated with exposures. The hypothesized
mechanism of carcinogenesis is based on the concept of nonthreshold effects (i.e., there is
essentially no level of exposure to a chemical that does not pose some probability of generating
a carcinogenic response).
In defining the potential carcinogenicity of a chemical contaminant to humans, EPA (CERCLA)
first evaluates the sufficiency of evidence of carcinogenicity from available data. The evidence
is characterized separately for human and animal studies as sufficient, limited, adequate, no data,
or evidence of no effect. The characterizations of these two sets of data are evaluated in
combination and the chemical is assigned a "weight-of-evidence" classification. EPA has five
groups of classification which are as follows:
A 
- 
Human Carcinogen.
Bl 
- 
Probable Human Carcinogen. Limited human data are available.
B2 
- 
Probable Human Carcinogen. Sufficient evidence of carcinogenicity in
animals and inadequate or no evidence in humans.
26
-r \\~\~
C 
- 
Possible Human Carcinogen.
D 
- 
Not Classifiable as to human carcinogenicity.
E 
- 
Evidence of noncarcinogenicity for humans.
For Group A, Bl, and B2 carcinogens, EPA typically derives a carcinogenic slope factor. Slope
factors for Class C carcinogens are derived on a case-by-case basis. The slope factor defines
quantitatively the relationship between dose and response as the plausible upper-bound estimate
of the probability of a response (i.e., development of cancer) per unit intake of a potential
carcinogen over a lifetime.
The slope factor is derived by EPA by selecting the most appropriate data set, extrapolating to
lower doses, determining equivalent human doses for the appropriate route of exposure
(ingestion or inhalation), and application of uncertainty factors. The resultant slope factor is
expressed in terms of risk per unit concentration of the compound (mg) per unit body weight
(kg) per unit time (day) or (mg/kg/day)'1.
4.2.2 
Slope Factors for Detected Chemical Contaminants
Oral and inhalation slope factors and weight-of-evidence classifications for potentially
carcinogenic chemicals detected at the Tutu Wells site will be presented in the risk assessment
for all chemicals detected at the site having such established values.
For certain carcinogenic PAHs, interim toxicity equivalency factors (TEFs) will be used in
conjunction with the benzo(a)pyrene slope factor since benzo(a)pyrene is the only carcinogenic
PAH having established slope factors (oral and inhalation).
27
TUT 
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5.0 RISK CHARACTERIZATION
In this section of the risk assessment, toxicity and exposure assessments will be integrated into
quantitative and qualitative expressions of carcinogenic risk and noncarcinogenic hazards. The
estimate of risk and hazard will be expressed numerically in spreadsheets contained in an
appendix.
Carcinogenic risks are estimated as the incremental probability of an individual developing
cancer over a lifetime as a result of exposure to a potential carcinogen. Per RAGS guidance,
the slope factor converts estimated daily intakes averaged over a lifetime of exposure directly
to incremental risk of an individual developing cancer. This carcinogenic risk estimate is
generally an upper-bound value since the slope factor is often an upper 95th percentile
confidence limit of the probability of response based on experimental animal data used in the
multistage model.
The potential for noncarcinogenic effects will be evaluated by comparing an exposure level over
a specified time period with a reference dose/concentration derived for a similar exposure
period. This ratio of exposure to toxicity is referred to as a hazard quotient. This hazard
quotient assumes that there is a level of exposure below which it is unlikely even for sensitive
populations to experience adverse health effects. If the hazard quotient exceeds one, there may
be concern for potential noncancer effects, however, this value should not be interpreted as a
probability. Generally, the greater the hazard quotient above unity, the greater the level of
concern.
In general, EPA recommends a target value or a risk range (i.e., hazard index = 1 or risk =
10"* to 10*) as threshold values for potential human health impacts. The results presented in the
spreadsheet calculations will be compared to these target values and discussed. These values aid
in determining the objectives of the baseline risk assessment which include determining whether
additional response action is necessary at the site, by providing a basis for determining residual
chemical levels that are adequately protective of human health, by providing a basis for
comparing potential health impacts of various remedial alternatives, and to help support selection
of the no-action remedial alternative, where appropriate.
Carcinogenic risks and noncarcinogenic hazard indices will be combined across pathways as
appropriate. Applicable or relevant and appropriate requirements (ARARs) will be presented
for the appropriate chemicals and will be compared to groundwater concentrations detected at
and around the site, as appropriate.
28
TUT 
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0864
6.0 UNCERTAINTIES IN RISK ASSESSMENT
In any risk assessment, estimates of potential carcinogenic risk and noncarcinogenic health
effects have numerous associated uncertainties. The primary areas of uncertainty and limitations
will be qualitatively discussed. In addition, central tendency calculations will be performed as
a quantitative measure of uncertainty, where appropriate.
29
TUT 
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0865
7.0 PRELIMINARY REMEDIATION GOALS (PRGs)
Chemical-specific PRGs are concentration goals for individual chemicals for specific medium
and land use combinations at CERCLA sites. PRGs will be developed based on the risk
assessment (i.e., risk-based PRGs). Site-specific parameters will be used in place of default
values, where appropriate, to reflect site conditions. Such risk-based PRGs are only initial
guidelines and do not establish that cleanup to these goals is warranted.
30
TUT 
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0866
8.0 SUMMARY OF THE BASELINE RISK ASSESSMENT
A summary section will be presented to briefly discuss the results of the baseline human
health risk assessment.
31
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0867
ECOLOGICAL RISK ASSESSMENT
An ecological assessment will also be completed by CDM Federal for the Tutu Wells site. This
ecological assessment will be performed to characterize the impacts or potential impacts of
chemical contaminants on ecological receptors at the site and adjacent areas. The objective of
the ecological assessment is to identify the probability and types of adverse effects that may
result from the presence of chemical contaminants.
The ecological assessment will be prepared in accordance with the following EPA guidance
documents:
• 
Framework for Ecological Risk Assessment (EPA/630/R-92-001, February 1992);
• 
Eco Update (Publication 9345.0-051, Volume I, Numbers 2 and 4, 1991 and
1992);
• 
Ecological Assessment of Hazardous Waste Sites: 
Field and Laboratory
Reference (EPA/600/3-89/013, March 1989); and,
• 
Risk Assessment Guidance for Superfund. Volume II. Environmental Evaluation
Manual (EPA/540/1-89/001, March 1989).
As described in the above EPA guidance, the key components to the ecological assessment will
be included and are as follows:
• 
Problem Formulation (Hazard Identification)
• 
Exposure Assessment
• 
Toxicity Assessment (Ecological Effects Assessment)
• 
Risk Characterization
• 
Uncertainties and Limitations
1) 
Problem Formulation
The problem formulation section will define the objectives and scope of the ecological
assessment. 
Description of site history, environmental setting, nature and extent of
contamination, and habitat characterization will be included.
If necessary, a selection of chemical contaminants of concern will be performed to identify
dominant site ecological risks. The selection process will involve for each detected chemical:
32
0868
TUT
OO7
• 
Evaluation of detection frequency;
• 
Comparison to background concentrations;
• 
Comparison to applicable and relevant and appropriate requirements (ARARs)
and/or media quality guidelines;
• 
Evaluation of physical/chemical properties; and,
• 
Consideration of potential toxicity.
Site-related indicator species will be chosen as ecological representatives of the trophic levels
and habitats on and surrounding the site. Selection will be based on an integration of the types
and distribution of contaminants of concern, habitats, range and feeding habits of potential
ecological receptors, and relationships between the observed/expected species in the area of
concern. Other considerations include species that may have beneficial uses to humans and
species that are Trustee or regulatory concerns.
For this qualitative or semi-qualitative ecological assessment, assessment endpoints will be
benchmark toxicity values from the literature. Where appropriate, risks to receptors will be
evaluated using ambient media quality criteria and similar guidance.
2) 
Exposure Assessment
The exposure assessment will discuss the magnitude and type of actual or potential exposures
of ecological receptors to site contamination. 
Exposure pathways and scenarios will be
presented.
Tutu Wells site chemicals have been detected in the groundwater, surface soil, and subsurface
soil. These environmental media will be evaluated in terms of potential exposure pathways.
However, it is anticipated that groundwater does not present an exposure pathway since
ecological receptors are likely to contact chemicals associated with the groundwater only when
groundwater discharges to surface water. Likewise, ecological receptor contact with subsurface
soil below approximately two feet is not expected, thus, subsurface soil data at greater than two
feet will not be considered.
A simplified food web will be presented as part of the exposure assessment section. The food
web will include ecological receptor groups expected to come into contact with site contaminants
and their trophic relationships.
3) 
Toxicity Assessment
The toxicity assessment will link potential contaminant exposure point concentrations to adverse
effects in selected ecologicial receptors. The goal of the toxicity assessment is to allow for the
determination of toxic effects of the Tutu Wells site chemicals of potential concern on selected
receptors. Ecological toxicity data will be gathered primarily from the following literature and
data bases:
33
TUT 
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0869
• 
EPA's ambient water quality criteria documents,
• 
Aquatic Information Retrieval Database (AQUIRE), and,
• 
Hazardous Substances Data Bank (HSDB).
The open literature will be also consulted, as necessary, for further lexicological information.
Additionally, site-related ecological effects information will be discussed in the toxicity
assessment.
4) 
Risk Characterization
Risk characterization will evaluate the evidence linking site contaminants with adverse ecological
effects. 
Risk characterization will integrate the exposure assessment with the toxicity
assessments. Characterization of risks to site ecological receptors will be determined on the
basis of comparison of ecotoxicological values from the literature with site-surveyed contaminant
levels. Risks to ecological receptors indicated by site-specific ecotoxicological information will
also be discussed.
5) 
Uncertainties and Limitations
%
In the process of developing a risk assessment, it is necessary to make assumptions..
Assumptions carry with them associated uncertainties which must be identified so that risk
estimates can be put into perspective. 
Uncertainties and limitations associated with the
ecological assessment will be discussed.
34
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