DSHW-2010-042646 - 0901a068801cf930

?rBoxTor"°"^ HAND DELIVERED
Brigham City, UT 84302
www.atk.com OCT 1 3 2010
ion t K onin UTAH DIVISION OF
12 October 2010 gQLID ^ HAZARDOUS WASTE
Scott T Anderson
Executive Secretary,
c/o UDEQ Division of Solid and Hazardous Waste
PO Box 144880
SALT LAKE CITY UT 84114-4880
Subject: ATK Launch Systems Promontory Facility, Responses to DSHW Comments on HHRA for
Groundwater March 2009, Promontory EPA ID #UTD009081357
Dear Mr. Anderson
Attached, please find the ATK Launch Systems Promontory Facility responses to DSHW comments
on the HHRA for groundwater March 2009. ATK has been in discussion with your office regarding
the many aspects of these comments and this submittal includes the investigation of metals
concentrations resulting from corroding stainless steel well screens.
If you have questions regarding these comments, please contact Paul Hancock at [phone].
1 certify under penalty of law that this document and all attachments were prepared under my
direction or supervision in accordance with a system designed to assure that qualified personnel
properly gather and evaluate the information submitted. Based on my inquiry of the person or
persons who manage the system, or those persons directly responsible for gathering the information,
the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I
am aware that there are significant penalties for submitting false information, including the
possibility of fine and imprisonment for knowing violations.
Sincerely,
David P. Gosen, P.E., Director
Environmental Services
October 11,2010
ATK Responses to Division of Solid and Hazardous Waste Comments on HHRA
for Promontory Groundwater, March 2009,
and Responses to Supplemental Comments from March, 2010
Introduction
In March 2009, ATK submitted a Human Health Risk Assessment (HHRA) for their Promontory
facility. The Utah Division of Solid and Hazardous Waste (DSHW) issued comments on the
HHRA on December 1, 2009 on the ATK received comments on the HHRA. Further
supplemental comments were issued by the DSHW on the risk assessment in March 2010.
Although the comments from the DSHW were extensive, they fell into a limited number of
categories:
The evaluation of each individual contaminant plume separately
Chemical selection and the use of small data sets
Current and future potenfial residential exposures
Background groundwater quality and metals
Future model generated groundwater concentrations
Vapor intrusion
Editorial comments, and the use of guidance
A conference call between the DSHW and ATK, and their respective contractors, was held on to
March 11, 2010, to discuss these major topics. It is ATK's understanding that the following
summary agreements were reached on the call.
• ATK will evaluate each groundwater contaminadon plume separately, and estimate the
risks for each plume. When a smaller plume is evaluated, the data set may be limited. The
chemical selection process will consider data trends to determine if the plume is stable.
Where the data are limited, the maximum concentration will be used in the risk assessment
process.
• ATK will evaluate a current potential residenfial off-site exposure scenario, assuming
household groundwater use (ingestion, inhalation and dermal contact) even though there
are no current residential receptors exposed to contamination from Promontory
groundwater, and groundwater quality is poor. This exposure will not include plant uptake
or other secondary exposure uptake pathways because the high level of total dissolved
solids (TDS) precludes vegetable gardens or rearing animals. Future on- and off-site
residential use scenarios will also be included in the HHRA, with future potential
concentrafions being derived from the revised DSHW-approved groundwater model.
• The selection of chemicals of potential concern will use a screening process where the
maximum concentrafion or the maximum detection limit of the data will be used rather
than the reporting limit. Non-detected chemicals with detection limits greater than their
Regional Screening Level will be evaluated and their impact on the risk assessment will be
reported in the uncertainty section of the risk assessment.
• The most current of all other guidance documents will be used in the revised risk
assessment, including the Regional Screening Levels and ProUCL.
October 11, 2010
• No chemical will be eliminated from the HHRA processed based on its detection
frequency, but chemicals with low detecUon frequencies are often not site related; they are
artifacts of the analytical process. These chemicals will be evaluated and their impact on
the risk assessment will be reported in the uncertainty section of the risk assessment.
• Groundwater quality is poor at Promontory due to high TDS, and ATK believes that
elevated on- and off-site groundwater metals concentrations are due to background or
problems with well screens. ATK will evaluate the risks associated with metals in
groundwater. However, this analysis will be conducted and presented in the uncertainty
section of the risk assessment. As part of this analysis, the risks associated with on-site
and up-gradient or background metals concentrations will be calculated. Where
groundwater metals are elevated due to anthropogenic sources, such as metal-well screens,
the risks will be calculated in the uncertainty section of the report and supporting evidence
for anthropogenic contamination will be provided.
• Groundwater arsenic concentrations vary across the sites, and appear elevated where
bioremediation is in process. ATK believes this variability is due to the natural variability
in metals at Promontory, the DSHW suspects it may be due to the remediation process and
has their contractor, TechLaw, investigating potenfial mechanisms for this process. The
DSHW will discuss their findings with ATK.
• The groundwater model for Promontory has been re-calibrated and the revised
groundwater model has been approved by the DSHW, and it will be used to calculate
future groundwater contaminant concentrations for each plume, and for off-site. In some
plumes, contaminant concentrations are expected to peak after more than 30 years, the
time period used to represent future potential exposure. Therefore, the length of time for
concentrafions to peak will be noted in the risk assessment should it impact future
residenfial exposure scenarios. For future potenfial on-site exposure concentrations,
residential exposure at each plume will be assessed.
• Vapor intrusion was evaluated in the risk assessment and found to be an insignificant
exposure pathway. However, the risk assessment will re-evaluate vapor intrusion at each
plume locafion by following the US EPA's 2002 vapor intrusion guidance. However,
most buildings at Promontory are located over deep groundwater (greater than 100 feet),
where vapor intrusion is not expected to be significant and is excluded under the guidance.
Where groundwater is shallower than 100 feet, vapor intrusion will be evaluated using the
Johnson-Etfinger model to determine, in collaborafion with the DSHW, where additional
vapor intrusion work may be necessary.
• ATK agreed to revise the risk assessment to address all of the editorial comments. ATK
also agreed to address all of the guidance related comments, such as to use the most
current risk assessment guidance documents available.
Each of the DSHW comments, and their supplemental comments, are provided below, with
ATK's responses.
October 11, 2010
Division of Solid and Hazardous Waste Comments on HHRA
for Promontory Groundwater, March 2009
General Response to the Utah Division of Solid and Hazardous Waste December 2009
Comments on the Human Health Risk Assessment
The Utah Division of Solid and Hazardous Waste (DSHW) provided 77 comments on the
Promontory human health risk assessment (HHRA), 5 supplemental comments and 16 additional
comments: a total of 98 comments in all. Although there are 98 comments, many of the comments
are the same comment repeated or reiterated in a different form. Out of these 98 comments there
are actually six key issues that will be resolved with the DSHW prior to preparing the revised
report. These issues are as follows:
1. Each Groundwater Plume will be a separate Exposure Unit
The DSHW's comment number sixteen requires that each source area and associated
groundwater contaminafion plume be evaluated independently as Exposure Units (EUs).
A preliminary list of these EUs is provided in Table I. The EU approach for groundwater
requires agreement on the groundwater contamination source aieas, the groundwater wells
for each source within the EU and the depth to groundwater to determine if a vapor
intrusion analysis is necessary, the inifial sampling date and data set for each EU. (DSHW
Comments: 13, 16, 20, 47, 48, 62, 63; Supplemental Comments: 2, 5). The data set for
each plume will be smaller and data adequacy for each plume may be compromised,
potenfially resulfing in the use of all detected constituents. (DSHW Comments: 4, 8, 9, 11,
22, 26, 27, 29, 30, 31, 35, 36, 37, 40 and 72)
2. Detecfion Limits and the Chemical of Potenfial Concern Selection Process
The selecfion of chemicals of potenfial concern (COPC) will screen the maximum
concentrafion or the maximum detecfion limit of the data in each EU against the RSL.
Non-detected chemicals with detecfion limits greater than their Regional Screening Level
(RSL) will be evaluated and their impact on the risk assessment will be reported in the
uncertainty secfion of the risk assessment. (DSHW Comments: 4, 5, 8, 21, 23, 28 and 29)
The Chemical of Potenfial Concern (COPC) selection process will use the most current
version of the EPA's Regional Screening Levels (RSL), and Vapor Intrusion (VI)
Screening Levels. (Additional Comment: 1)
3. Background Metals and High Metals in Groundwater
Background groundwater quality for arsenic, molybdenum, chromium and lead are key
issues. Groundwater and surface water sampling methods (filtered versus unfiltered).
Method Detecfion Limits (MDLs) (greater than RSL), the construcfion of groundwater
wells with stainless steel screens and their degradation, and the specific background data
sets for each EU are all unresolved. Based on the March 11, 2010 meefing with the
DSHW a risk assessment will be prepared for metals in on- and off-site groundwater, and
off-site surface water. This analysis will be included in the uncertainty secfion of the
report. The risks from on-site metals and from metals that might be attributed to
background groundwater will be calculated. The incorrect attribufion of arsenic on-site
may lead to arsenic concentrafions being incorrectly attributed to on-site sources stemming
October 11,2010
from ATK's operations when tiiey are in fact background derived. Further, the risk
assessment will also evaluate the sources and risks from other metals, such as chromium
and molybdenum that may be from well screens, in the uncertainty secfion of the HHRA.
(DSHW Comments: 7, 16, 24, 25, 26 and 27; Supplemental Comments: 3, 6, 7 and 9)
4. Residenfial Exposure, Groundwater Modeling and Future Potenfial Groundwater
Contaminant Concentrations
The risk assessment will include a current off-site residential exposure scenario, assuming
household groundwater use (ingestion, inhalation and dermal contact) even though there
are no current residential receptors exposed to contamination from Promontory
groundwater, and groundwater quality is poor. The ingestion of vegetable and meat from
gardens and farms irrigated with contaminated water will not be included because at the
March 11, 2010 meeting with the DSHW it was agreed that groundwater is unusable for
these purposes.
Future on- and off-site residential use scenarios will also be included in the HHRA, with
future potential concentrations being derived from the revised DSHW-approved
groundwater model.
The model's ability to address contaminant fate and transport on a plume-by-plume basis
and in two additional springs has yet to be determined. The uncertainty in groundwater
concentrations and risks will be discussed in the uncertainty section of the revised HHRA.
(DSHW Comments 12, 38, 55, 57 and76)
At the meeting with the DSHW on March 11, 2010, the DSHW proposed using the current
maximum groundwater concentration to represent the future groundwater exposure point
concentrations. This approach does not incorporate the DSHW-approved model and ATK
believes this represents an overly conservative approach for the future Reasonable
Maximum Exposure (RME) concentration scenario. The model has shown that
groundwater contaminant concentrations do not peak until over 100 years from now, and
future potential exposure scenarios are typically 30 years. The HHRA will discuss the
RME exposure scenarios relative to the highest predicted groundwater concentration and
future unrestricted groundwater use.
Direct exposure to on-site groundwater occurs at Plant 3. Groundwater exposure point
concentrations will assume contact occurs both with and without remedial or institutional
controls at the wellhead. For off-site groundwater, the revised risk assessment will assume
groundwater is used for all domestic purposes with the following direct exposure
pathways: ingestion, dermal contact and inhalation. (DSHW Comments: 10, 17, 23, 39, 41,
44, 45,46,53,61,65,66 and 71)
5. Vapor Intrusion
A revised approach to vapor intrusion (VI) by the DSHW rejected use of the Johnson-
Ettinger model in favor of the EPA's 2002 VI guidance (Additional Comment: 3). Where
groundwater is deeper than 100 feet, typically most of Promontory, guidance allows for
the elimination of the VI pathway. This screening will be undertaken at Promontory. At
locations where there are buildings over groundwater that is shallower than 100 feet the VI
October 11,2010
guidance requires a screening of the data against residential VI screening levels. Where
these levels are exceeded additional data may be collected, following further discussions
with the DSHW and prior to the initiation of the revised risk assessment.
6. Other comments concerning clarifications, additions to the text or explanations of
approaches to the risk assessment are addressed in the comment responses below, but these
specific comments will be considered and addressed in a revised risk assessment. (DSHW
Comments: 5, 6, 9, 14, 15, 18, 19, 28, 32, 34, 43, 49, 50, 51, 52, 54, 56, 58, 59, 60, 64, 67,
68, 69, 70, 73, 74, 75, 77; Supplemental Comment: 10, 12, 13; Additional Comment: 4, 5,
6).
October 11,2010
Table 1
Preliminary On-site Exposure Units
Source Area or Exposure General Description Groundwater Wells '"^
Unit
E519 Laboratory Sump Northern Manufacturing Plant J-l,P-l,P-5,P-8, P-9;
M508-l,M508-2, M508-3,
M508-4M508-B-1,
E585 Laboratory Sump Northern Manufacturing Plant P-2, P-6, P-7
Abandoned Landfill Northern Manufacturing Plant LF-l,LF-2, LF-3
Building M636 Northern Manufacturing Plant M-363B1
M-136 Burning Grounds Central Burning Grounds A-wells(l-9),
B-wells (1-5)
C-wells(l-3,5,7)
D-wells (2-6)
E-10,
Perched Aquifer above the Perched Plume Area A-2, A-3, A-10
M136 Burning Grounds B-9, B-10, C-4
Drum Storage Area Central Manufacturing Area F-l,E-l E-4, E-5, E-6
Perched Aquifer Central Manufacturing Area J-2, J-3, M39-Bl,TCC-2
Plant 3 Sump Plant 3 TCC-3, X-4
Down-gradient Plume Near Springs G-4, G-5,J-5,J-6
Well G-6 Plant 3 G-6
Off-site Exposure Units
M-153 Drain field Off-site with possible migrafion F-5, B-8, E-2, B-6, B-7, G-
back on-site 2,G-l,EW-6, H-4, H-3, H-
2, BC-2, H-5, H-l,H-6
Shotgun Spring Down gradient of M-154 Drain
field and/or Central
Manufacturing Area
J-5,J-6
Pipe Spring Down gradient of M-154 Drain
field and/or Central
Manufacturing Area
J-5,J-6
Down-gradient Plume Near Springs BC-6, G-3, BC-4
Horse Springs Down gradient of Plant 3 To be idenfified
Fish Spring Down gradient of Plant 3 To be idenfified
Fork Springs Unknown To be idenfified
Conner Springs Unknown To be idenfified
(a) Not all of the wells for each EU are included in this list, the final list of wells will be
agreed with the DSHW prior to preparing summary statistics for each EU.
October 11, 2010
General Comments
1. In addition to addressing the specific comments, the risk assessment should be revised so
that the reader is able to duplicate the analysis. As written, the risk assessment has
organizafional issues and is difficult to follow.
Response: The risk assessment will be revised to include each separate groundwater plume as
a separate exposure unit. The report will be revised to systemafically identify each
exposure unit, the associated data and its quality, the potential exposure receptors and risks
for each unit. The risk assessment will be revised to respond to this comment and make
the risk assessment easy to follow.
2. Please add figures that show the locations of buildings, property lines, monitoring wells
and springs. Figures that include groundwater contaminant isopletiis would be very
helpful.
Response: Consistent with the above comment (general comment #1), the revised risk
assessment will provide a figure showing the location and concentration isopleths for each
exposure unit, depth to groundwater and the building located over the chemicals in
groundwater and the location of groundwater springs and their associated ponds.
3. Please provide electronic copies of the ProUCL spreadsheets and Johnson and Ettinger
spreadsheets.
Response: ATK will provide all data, risk assessment calculations and spreadsheets
electronically to allow for duplication of the risk assessment.
Specific Comments
4. Section 2.0, Data Evaluation and Selection of COCs. The data set used in the HHRA
appears to be incomplete. Of particular note is the absence of data for wells A-4, B-2, the
D-series wells, E-7, EW-6, F-2D, F-3, G-2 the H-series wells and TCC2. Average
concentrations of constituents, maximum detections and frequency of detection values
used for screening constituents or calculating exposure concentrations all have the
potential for being impacted by not including data for these wells.
In addition, the data used from the 2004 to 2008 period doesn't consider the well locations
or number of samples per well. This is an issue because most of the data from this period
is from wells that are located near the edge of the contaminant plume. These wells are not
nearly as contaminated as the wells located closer to the sources of contamination. An
average calculated with these data and used to represent contaminant concentrations for
the site will be biased low. The Division would like to discuss with ATK how the data set
used in the HHRA should be compiled. In regard to the D-series wells, the Division
disagrees with the decision to exclude them from the risk assessment. The pilot test that is
being conducted in the area does not justify this decision. The Fall 2008 data showed that
several of the "D wells" (D-4, D-5 and D-6) had large increases in perchlorate
October 1 1, 2010
concentrations over the last time they were sampled years ago. The groundwater model
has been revised to include the Fall 2008 data for these wells.
Response: Groundwater wells for the risk assessment were selected based on the wells
agreed with the DSHW for the groundwater model. Other wells at Promontory have been
abandoned, have been sampled inconsistentiy or are in remediation (e.g., the D-series
wells). At these remediation wells, the model would be required to estimate decreasing
groundwater constituent concentrations while at other wells, not in remediation, the
decrease in constituent concentration would be at a different rate. Therefore, the
estimation of future projected concentrations at the D-wells would be inconsistent.
Using an EU approach, each unit will be evaluated independenfiy, including the area in
remediation. The data from all of the groundwater wells within an EU will be used to
select COPC and calculate exposure point concentrations (EPC). Typically five years of
groundwater data will be used. However, each EU will be treated individually to
determine if the plume is stable, and if older data are available, to determine if these
historical data represent current conditions. The wells containing constituents at the
burning grounds (A-wells and D-wells) will be evaluated to determine constituent data
trends, and the COPC ninety five percent upper confidence limit of the mean (95% UCL)
concentration will be used to represent the EPC for exposure. Future potential exposure
will be evaluated using the 95% UCL groundwater constituent concentration from the
DSHW-approved groundwater model.
5. Section 2.1 Data Usability Evaluation. Detection Limits. Page 6. Please include
conclusions regarding the analytes with detection limits higher than MCLs. Specifically,
does the data meet the objectives of the risk assessment?
Response: The report will be updated to evaluate the analytical program by identifying the
groundwater analytes with method detection limits (MDL) that exceed their RSL. There
are two types of samples where the MDL is higher than the RSL:
• Chemicals where the program's MDL does not meet the RSL, e.g., arsenic and lead,
and
• Chemicals where sample dilution has raised the MDL in a particular sample or group
of samples (e.g., where 1,1-dichloroethene was not detected but trichloroethene was
present at high levels raising the detection limit).
The report will identify the analytes that do not meet the needs of the risk assessment. For
example, the MDL does not meet the RSL for 1,1,2,2-tetrachloroethane, 1,2,3-
trichloropropane, 1,2-dibromo-3-chloropropane, 1,2-dibromoethane, dibromomethane and
hexachlorobutadiene because the analytical laboratory is not capable of achieving the
groundwater screening level. Tables with the following information will be provided in
the next risk assessment report:
• Analytes with their DL lower than their RSL
• Analytes with their EQL lower than their RSL
October 11,2010
However, as stated below (comment-responses number 6), the MDL is considered
sufficiently accurate for the purposes of risk assessment and ATK considers the screening
of the RSL against the MDL to be acceptable for screening groundwater data to determine
the Chemicals of Potenfial Concern (COPCs).
6. Secfion 2.1 Data Usability Evaluation. Detection Limits. Please provide support for the
statement that J-qualified data tends to overestimate the quantity of an analyte present.
Response: Based on discussions with Scott Eraser of ATK's analytical laboratory, J-
qualified data provide an estimate for values between the MDL and the EQL, often called
the reporting limit (RL). The MDL is established by ATK based on a statistically derived
method detection limit process, with a 99'*^ percent confidence interval and measures
constituents with a high degree of certainty. This is not the instrument detection limit.
Therefore, concentrations above the MDL are considered quite accurate even though they
are below the lower point on the "standard curve". The J-qualifier is considered to
potentially overestimate the constituent concentration because of the presence of other
constituents that might be present with the target constituent and that increase the target
constituent's concentration. To the extent these constituents are present, tiiey tend to lead
to a slight overestimate of the concentration of an analyte.
7. Section 2.1 Data Usability Evaluation. Background Samples. The Division understands
that the groundwater at ATK is high in TDS; however, it has not been established that
"inorganic ion and metals are not Chemicals of Concern (COCs) at Promontory." The
Division conducted an assessment of COCs in groundwater at ATK before reissuing the
Post Closure Permit in 2007. The list of COCs in the Permit includes arsenic, barium,
beryllium, chromium, cobalt, molybdenum, perchlorate and nitrate. Since it has not been
established that these COCs are within background, they should be included in the risk
assessment.
During the groundwater monitoring program, wells A-10, C-6 and C-8 have been the
designated background wells. Groundwater TDS values vary significantiy at ATK
depending on the location and aquifer. It is appropriate to use the H wells cited in the text
for background for groundwater off-site or located beneath the valley floor, but they
should not be used for background for other areas (particularly perched zones) at the
facility.
Response: As discussed with the DSHW on March 11, 2010, and as indicated in
Attachment A, arsenic levels are elevated throughout the area near Promontory and the
sources of arsenic are believed to be related to elevated levels of arsenic in soil and the
potential presence of solids in groundwater samples as shown in Attachment A, Figure 1.
The approach to metals and nitrate in the revised risk assessment will be to calculate the
risks for on-site and up-gradient, or background metals and nitrate in the uncertainty
section of the report allowing for a demonstration of the range of arsenic risks potentially
attributable to ATK's operations.
Chromium and molybdenum were found at elevated levels in on-site groundwater
monitoring wells. ATK believes these elevated concentrations are due to the stainless steel
October 11, 2010
well casings and screens used in the construction of the wells. Attachment A also provides
data supporting this assertion by showing groundwater concentrations of chromium and
molybdenum found in wells of PVC and stainless steel construction. The concentrations
of chromium and molybdenum in PVC wells are significantiy lower. At the request of the
Division, four wells with historically high unfiltered total chromium concentrations were
sampled and analyzed for filtered and unfiltered total chromium and hexavalent chromium.
These results are in Attachment A.4. The data shows that the high total chromium values
when filtered are reduced to non-detect with the excepfion of well E-5 that showed low
values of both total and hexavalent. In the other wells, hexavalent chromium values were
non-detect. The E-5 values appear to be a data outiier as there is no explanation for this
detection, however we will continue to evaluate this anomaly. The approach to chromium
and molybdenum in the risk assessment will be consistent with that for other metals. Again
in the uncertainty section of the report, chromium and molybdenum concentrations and
risks for on-site groundwater wells with different completion characteristics will be
compared with the risks for up-gradient wells with similar construction to demonstrate the
range of risks potentially attributable to ATK's operations and monitoring procedures.
The following inorganic constituents will also be evaluated in the uncertainty section of
the risk assessment: barium, cadmium, cobalt, lead, selenium, silver, tin and zinc.
Background wells will be selected for each exposure area in conjunction with the DSHW.
8. Section 2.1.1 On-Site Groundwater. Please add the groundwater data that wasn't placed in
the data set used for the HHRA in the data set for the revised HHRA. Chlorobenzene,
chloroform and cis-l,2-dichloroethene are all COCs included in the Post-Closure Permit
and should be included in the HHRA.
Response: Groundwater at Promontory has been monitored for many years and it contains
data from a number of groundwater wells that have been abandoned or that are no longer
sampled, and historical data may not represent current groundwater conditions. Further,
an exposure unit approach will be used, as required by the DSHW. For the specific
exposure units identified in Table 1, the groundwater monitoring wells, well sampling
dates and analytes will potentially vary for each EU.
Chlorobenzene, chloroform, and cis-l,2-dichloroetiiene were included in the COC
screening process. Chloroform was identified as a COC for on-site, while the other two
chemicals did not have maximum concentrations that exceeded their risk-based screening
level. These chemicals will be re-screened for each EU to determine if they exceed the
most current RSL.
9. Section 2.1.1 On-Site Groundwater. Page 11. The statement that RDX and HMX have
"limited solubility and low mobility" is incorrect. These compounds have low K^^ values
and are highly mobile. Please revise the text. Detections of RDX and HMX have been
quite limited historically; however, more data exists for these compounds dated pre-2004.
The data for these compounds that should be included in the risk assessment should be
discussed.
Response: The extent of RDX and HMX data to be used in the risk assessment will be
discussed and agreed with DSHW prior to revision of the risk assessment. There are other
October 11,2010
factors that need to be considered besides KQC values when evaluating HMX and RDX
mobility in soil that are likely better indicators such as water solubility and adsorption to
clay or other soil particles. The use of Koc implies that the compound sorbs only to the
organic carbon of the soil and does not account for any interactions with non-carbon
components. In our experience in soil clean-ups we have found at several locations a
distinct high concentration layer of HMX after 30-t- years of disposal and water infiltration.
The following are some references that show the wide Koc variability for these compounds:
• Organic carbon partition coefficient (K^c) values of HMX range from 3.5 to 670
(Burrows et ai, 1989; Monteil-Rivera et a/., 2003). If released to water, HMX
is expected to adsorb to solids and sediments based upon a K^c of 670
(Spanggord etal., 1982).
• Where Koc is the organic carbon partition coefficient, 2.00 for RDX and 0.54 for
HMX (Rosenblatt, et al. 1991). Based on these equations, approximately 2% of
the RDX and 0.5% of the HMX in a soil-water environment would be absorbed
to the soil for every 1% of organic carbon content. This suggests that sorption
will have a minimal retardation effect on the transport of RDX and HMX and
that absorption should not be a major factor in the remediation of contaminated
soil and groundwater.
• Based on the calculated soil adsorption factor (log Koc of 0.54), HMX is
expected to have high mobility in soil. However, the extent of migration to
groundwater is limited by the relatively low solubility of HMX in water (6.63
mg/L) (EPA 1988). Therefore, the migration of HMX through soil is expected to
be slow, resulting in low concentrations in groundwater (EPA 1988).
10. Section 2.1.2 On-Site Process Water. The risk assessment should be conducted assuming
a baseline condition, i.e., an absence of remediation, administrative, or engineering
controls. The data used to evaluate risk should be from before the wellhead treatment at
Plant 3.
Response: The risk assessment submitted to the DSHW included the risks under baseline
conditions. However, the revised risk assessment will include exposure pathways in
absence of remediation, administrative, institutional or engineering controls. This will
include the direct use of on-site groundwater at Plant 3 for the following exposure
pathways: worker groundwater ingestion, dermal contact and the inhalation of
contaminants, animal groundwater ingestion and farmer ingestion of beef A beef
exposure scenario was also assumed at the ponds where the surface water constituent
concentrations were used with plant concentrations, and no loss of perchlorate was
assumed.
11. Section 2.1.3 Off-site Groundwater. Please include the data that was left out of the
database in the revised risk assessment.
Response: The revised risk assessment will contain the omitted data for off-site
groundwater. The extent of the historical data included in the risk assessment will be
discussed and agreed with DSHW prior to revising the risk assessment.
11
October 11, 2010
12. Section 2.1.4 Off-site Surface Water. Please add Fork Springs and Connor Springs to the
list of springs where the potential exists for groundwater to become surface water off-site.
Response: Fork Springs and Conner Springs will be added to the list of springs where
Promontory groundwater may become surface water. However, there is no evidence that
these springs are contaminated by activities at Promontory. Further, these springs are
beyond the boundary of the DSHW-approved groundwater model.
13. Section 2.1.4 Off-site Surface Water. The data was averaged across the four springs.
Please provide information to support the assumption that averaging is appropriate while
considering the following questions. Why is a receptor likely to visit each spring equally?
Are the contaminants and concentrations similar for each spring? As discussed in the text,
perchlorate concentrations vary from spring to spring, ranging from non-detect to 430
\ig/L. Based on the information provided, averaging the data across the four springs is
inappropriate.
Response: The primary receptor at the springs is an environmental worker who samples the
springs equally. Based on the DSHW's comments, the risk assessment will be revised to
address each pond as a separate EU and estimate the risk at each spring individually.
14. Section 2.2.1 On-site Groundwater. To be consistent with UAC R315-101-5.2, the
problem statement should read, "Is there a present or potential future risk to workers and
off-site receptors from groundwater at Promontory?" Please revise.
Response: The risk assessment will be revised to incorporate the language in UAC R315-
101-5.2.
15. Section 2.2.1 On-site Groundwater. Please provide additional information to support that
arsenic is not a contaminant. Also, please review the following sentence for accuracy.
"Arsenic is considered a background constituent and, although the data for October and
November 2008 are inaccurate, they were not used in the risk assessment."
Response: Please see the response to comment number 7, and Attachment A. The risk
assessment will evaluate the data for arsenic in each EU and address the risk from arsenic
in the uncertainty section of the risk assessment.
16. Section 2.2.1 On-site Groundwater. Please provide data to support the averaging of the
groundwater across the site. Data should not be averaged across areas with different
statistical populations such as contaminated areas with uncontaminated areas.
Response: The risk assessment will be revised to address each groundwater source and
constituent plume with different statistical constituent populations, and a separate risk
assessment for each EU will be provided in the revised RA. Table 1 shows the
preliminary EU source areas. These are also identified in Plate 1.
The units will be agreed with the DSHW prior to beginning the revised risk assessment.
As a consequence of this approach, a separate conceptual site model will be developed for
October 11, 2010
each groundwater contaminant EU. Current groundwater concenU-ations will be taken
from the database for each unit. Future potential groundwater concentrations will be
derived for each EU using the DSHW-approved groundwater model.
Vapor-intrusion occurs at a specific location, each EU will be evaluated to determine if a
building is located over a groundwater plume with its own distinct statistical distribution
and information such as the depth to groundwater, and volatile constituent concentrations
beneath identified buildings will be used to evaluate the potenfial for vapor intrusion at
each EU.
17. Section 2.2.1 On-site Groundwater. The boundaries are defined as current conditions.
Why wouldn't future conditions be considered? Are the contaminated areas of
groundwater predicted to remain the same size?
Response: The current boundary for each EU is based on the on-site groundwater data.
Future potential groundwater constituent concentrations at each EU will be derived from
the DSHW-approved model, and the extent of chemical migration will also be taken from
the model. Future off-site conditions will consider both the down-gradient extent of
constituents, the point of the maximum on- and off-site concentration, and the time taken
to reach maximum groundwater concentrations.
18. Section 2.2.1 On-site Groundwater. The decision rule should be related to the problem
defined in the previous steps, i.e., is there a present or potential future risk to workers and
off-site receptors from groundwater at Promontory? For this problem, the criteria listed in
UAC R315-101-6 are the decision rule. Please revise.
Response: The risk assessment will be revised to incorporate the language. UAC R315-101-
6 discusses developing a site management plan after the risk assessment has been
submitted and approved. It discusses taking corrective action for risks in excess of 10"'*,
and that no further action may be necessary for risks less than 10"^. The risk assessment
assumptions will be updated to ensure that the revised risk assessment is adequate to
comply with this section of the code.
19. Section 2.2.1 On-site Groundwater. "No limits on decision errors are specified for the
data...." Please explain the intent of this sentence. As currenfiy written, esfimating the
decision errors for the problem would be difficult. Quantitative estimates of decision
errors are easier if the problem statement is more concise. For instance, a specific piece of
the original problem statement could be, "Are concentrations of trichloroethene in Plant 3
groundwater less than 5 //g/L?" Specifying acceptable rates of decision errors can be used
to specify a minimum number of samples required to meet the acceptable rates. Please
revise the data quality objectives or consider deleting the discussion. The data quality
objectives process is designed to optimize data collection efforts such as sampling. ATK
is not proposing to collect any additional data, so the purpose is unclear. If the intent is to
specify what criteria will be used to determine if the existing database is adequate for the
risk assessment, then specific criteria should be proposed with regards to a decision rule.
Response: The comment is noted and the section will be deleted to avoid confusion.
13
October 11,2010
20. Section 2.2.2 Northern Manufacturing Plant. How large was the area over which
contaminant concentrations were averaged? How does this compare to the size of
commercial building? Is the average representative for a building?
Response: The revised risk assessment will contain text that is clearer. Vapor intrusion
modeling in the risk assessment used the maximum groundwater concentration for each
COPC beneath buildings in the northern and central manufacturing areas. Concentrations
were not averaged.
In the revised risk assessment, the EPA's 2002 Vapor Intrusion Guidance screening
process will be used. Constituents in groundwater at depths greater than 100 feet will be
excluded from the risk assessment. Current groundwater concentrations in each EU will
be used to represent current conditions, and for each EU location with a building over
volatile constituents the Johnson-Ettinger model will be used to screen locations for further
investigation in conjunction with the DSHW. For future potential conditions, the DSHW-
approved model will provide the groundwater concentrations over time, and the same
approach will be taken as for current conditions.
21. Section 2.2.2 Northern Manufacturing Plant. A separate contaminant plume that includes
VOCs is located in the area of monitoring wells P-2, P-6 and P-7. This plume is in a
perched aquifer, at a depth of approximately 75 feet. In the Fall of 2008, TCE was
detected at 2,880 //g/L in well P-6. The risk assessment needs to include an evaluation of
the risk associated with this contaminant plume. Is vapor intrusion into the buildings in
this area (M-585 and others nearby along "G Avenue") a concern?
Response: An EU approach will be used in the revised risk assessment, and the E585
Laboratory sump (Wells P-2, P-6 and P-7) will be included in a separate analysis.
22. Section 2.2.3 Central Manufacturing Plant. This section is uncleai" and should be revised
for clarity. Where is well F-4 relative to the great distance between E-8 and E-9? Was
1,1-dichloroethene (1,1-DCE) evaluated for vapor intrusion? 1,1-Dichloroethene is a
volatile organic compound that should be considered for vapor intrusion. Where is well F-
9? Please consider including a figure that shows building locafions, property lines, well
locafions, and contaminafion isopleths.
In regard to the perceived lack of data, was the use of data dated prior to 2004 considered?
More data exists for wells F-4, E-8 and E-9 that was collected before 2004. The distance
between wells E-8 and E-9 and the four orders of magnitude range in concentrafions
doesn't support the use of an average concentration in the indoor air calculation. The
maximum concentration detected in the area (well E-9) should be used to estimate
exposure concentration. Was future risk looked at for these localized areas? For TCE, the
highest contaminated zone in the plume is just upgradient of the central manufacturing
plant. The contaminant plume in the regional aquifer also extends below the area around
buildings Al and A4. The TCE concentration in the plume in this ai-ea is above 1000 //g
/L. Why wasn't the potential for vapor intrusion evaluated for this area?
14
October 11,2010
Response: 1,1-Dichloroethene was evaluated in the vapor intrusion process and was not
determined to be a COPC for the Central Manufacturing Area because the maximum
concentration of 1040 //g /L does not exceed the GWSL of 1,800 //g /L, however, this was
for ingestion only. The chemical will be re-evaluated in the revised risk assessment and
the potential risks from 1,1-dichloroethene vapor intrusion will be evaluated at that time.
Groundwater in the Northern and Centi-al Manufacturing area is deeper than 100 feet, so it
is expected that 1,1-dichloroethene will be screened from the risk assessment in these
areas. Plate 2 shows the Promontory wells shallower than 100 feet. The wells with 1,1-
dichloroethene above the non-cancer vapor intrusion screening level of 190 //g /L, from
EPA 2002, are shown where there is a perched aquifer only (at wells J-2, J-6 and J-7). The
highest 1 ,l-DCE concentration in any of these wells is 2.8 //g /L.
23. Section 2.2.4 Plant 3 Water. Exposure point concenfi-ations are estimated assuming an
absence of remediation or engineering controls for the risk assessment such as the carbon
filter ATK uses at the wellhead. The exposure point concentrafion should be recalculated
using pre-treatment concentrafions.
Response: Risk will be calculated assuming no remediafion, engineering or administrafive
controls are in place. Also see comment response 61.
24. Section 2.2.5 Off-site Groundwater. Please reference where in the report background is
evaluated and the where the methodology is described in detail. The rafionale presented is
inadequate to support that arsenic is not a contaminant when concentrations up to 896 //g
/L were detected and "only four of the off-site results exceed the background range."
Response: Please see the response to comments 7, 15 and 25. The risks associated with
background metals and inorganic chemicals will be calculated and included in the
uncertainty section of the risk assessment. Further, the risks associated with on-site metals
and inorganic chemicals will also be calculated and included in the uncertainty section of
the risk assessment.
25. Section 2.2.6 Off-site Surface Water. Please define "regulatory goals" in the table. Please
explain why the groundwater wells are representative of background for arsenic and lead
in each spring. Are the detection limits adequate to evaluate background? Are these
results from filtered or unfiltered samples?
Response: The term "regulatory goal" was intended to mean the Maximum Contaminant
Limits. Because there are no residential receptors the MCL was proposed as a remediafion
goal.
Based on the DSHW required sampling procedures, groundwater and surface water
samples were unfiltered. Using unfiltered samples in an area of high metals may increase
the variability in the data.
Background groundwater wells near the springs will be identified, where possible, to
determine background metal and inorganic chemical concentrafions for each separate
spring.
15
October 11,2010
The DLs for metals will be evaluated relative their RSL. The DLs for some constituents
are adequate to meet their RSL and some are not. This will also be evaluated in the
uncertainty section of the risk assessment.
26. Section 2.2.7 Off-site Sediment. Please explain why one sediment sample from each
spring is adequate for characterizing sediment. What was the detection limit for arsenic?
Soil and sediment samples from this area of Utah typically contain detectable arsenic. Is
lead a contaminant?
Response: There is only limited data available for soil and sediment at the springs and
additional samples are needed. ATK and the DSHW will collaborate to determine the
dataset prior to preparation of the revised risk assessment. The MDL and EQL for arsenic
in sediment were 2 and 10 micrograms per gram (jUg/g), respectively. Lead was not an
analyte for sediment in the November 2008 sampling event. Therefore, no data exist for
lead in soil or sediment at the springs.
27. Section 2.3 COC Selection Process. The "informal process" used to conduct background
comparisons is not consistent with the USEPA Region 8 COC guidance (cited as U.S.
EPA, 1994), is inadequately described, and appears unlikely to meet the technical rigor
appropriate for eliminating substances present above risk-based screening levels as
background. In the absence of appropriate background comparisons, the potential health
risks from all inorganic constituents should be calculated.
Response: The risk assessment will be revised to incorporate a background analysis for
each groundwater exposure unit, as discussed in comment response number 7, 15, 24, 25
and 26. The following inorganic constituents will be evaluated in the uncertainty section of
the risk assessment: arsenic, barium, beryllium, cadmium, cobalt, chromium, lead,
molybdenum, selenium, silver, tin and zinc, and nitrate. Arsenic, chromium, and lead
were the only inorganic constituents identified as having a maximum concentration above
the risk-based screening level. Nitrate will also be evaluated.
28. Section 2.3 COC Selection Process. Evidence of historic use is a useful criterion but
should be noted to not be consistent with U.S. EPA (1994).
Response: ATK disagrees with this comment. Within the USEPA Region 8 Superfund
Technical Guidance Evaluating and Identifying Contaminants of Concern for Human
Health, (EPA, 1994) Step 6 states "Is there historical evidence of the compound at the
site?" In cases where a constituent has been detected one time it is important to know if the
chemical was ever used at a facility because it may be an artifact.
29. Section 2.3.4 Detection Limits and Detection Frequency. Was the detection frequency for
constituents calculated for each well independenfiy, or site-wide? In addition, please
explain why the detection limits for arsenic and lead in groundwater were adequate.
Response: The detection frequency calculation was undertaken for each constituent within
the groundwater database site wide for on-site and site wide for off-site, respectively.
16
October 11,2010
Detection frequency was not calculated for each groundwater EU independentiy. In the
revised risk assessment the COPC evaluation will be undertaken on an EU basis. As noted
above, the detection limits for arsenic and lead will be compared to their RSLs.
30. Section 2.3.5 Other Factors in COC Selection Process. Please review this section and edit
as necessary for clarity. For instance, was the process limited to COCs that were not
detected? What are the COCs anticipated to be selected?
Response: The text will be revised for clarity.
31. Section 2.4 COC Selection Process Results. What constituents were eliminated from
further consideration because they were not detected but the detection limits were above
the appropriate groundwater screening levels?
Response: The constituents 1,1,2,2-tetrachloroethane, 1,2,3-trichloropropane, 1,2-dibromo-
3-chloropropane, 1,2-dibromoethane and dibromomethane were not detected in on-site
groundwater and the detection limits were above the associated risk-based screening level.
These chemicals were not carried forward in the risk assessment.
In the revised risk assessment, for non-detected chemicals, a chemical's DL will be
compared to its RSL and discussed in the uncertainty section of the risk assessment.
32. Please define the difference between a regulatory COC and a COC.
Response: The term "regulatory COC" was intended to indicate a chemical that exceeded
the MCL, as opposed to a COC that exceeded the risk-based screening level. Chemicals
exceeding their MCL but not their GWSL were not taken through the risk assessment
process.
In the revised risk assessment a regulatory goal, such as the MCL, will not be used, only
the RSL.
33. Groundwater screening values should include all relevant routes of exposure (e.g., dermal
and inhalafion) and should include considerafion of cumulative exposures to multiple
chemicals to be consistent with UAC R315-101.
Response: There are no screening levels available that include ingestion, inhalation and
dermal exposure. Also, no available screening levels include ingestion, dermal contact
and vapor intrusion.
It was agreed in the meeting with the DSHW on March 11, 2010, that RSLs that do not
include dermal exposure are acceptable. See also comment response number 41.
34. The tables provided in Appendix 2 are incomplete. Please revise the tables to show the
reason and comparison values for substances eliminated as COCs.
17
October 11,2010
Response: The appropriate appendix of the revised risk assessment will include all
processes and calculations. The text and uncertainty section will be expanded to include a
discussion of constituents that were eliminated as COPCs.
35. Section 2.4.1 On-site Groundwater. The discussion in this section regarding the frequency
of detection of COCs doesn't consider the locations of constituents that were detected. If a
well where a constituent was detected is only included in the data set once or twice, than a
potential COC could be dropped regardless of the number of times or at what
concentration the constituent was detected in that well. All constituents (except
background) that exceed the groundwater screening level should be included as a COC for
further evaluation regardless of the detection frequency.
Please explain why RDX was dropped as a COC? Why isn't the limited RDX data a
significant data gap?In regard to arsenic and chromium, concentrations have been detected
that appear to be above background and exceed PRG levels. It hasn't been established that
these metals are within background concentrations. Please revise the COC selection
portion of the risk assessment to address these metals.
Response: Using an EU approach the amount of data for each plume will be considered
independentiy. Eliminating a chemical based on detection frequency allows for the
exclusion of laboratory artifacts and infrequenfiy detected chemicals. Conducfing the risk
assessment for every chemical detected one time or more, in each plume, through multiple
exposure pathways will lead to a large, overly cumbersome and overly conservative risk
assessment. When a constituent that is a common laboratory artifact is only detected two
or three times in over 270 samples it is likely unrelated to ATK's operations and should be
eliminated from the site-related risk analysis.
RDX was detected infrequentiy. However, using an EU approach RDX may be retained
through the COPC selection process.
36. Section 2.4.1 Active Remediation Area. The contaminant cis-l,2-DCE was detected prior
to the pilot test and in other areas at the facility. It is understood that with the degradation
of TCE, the concentration of cis-1,2-DCE will increase. How does ATK propose to
address this constituent?
Response: Cis-1,2-dichloroethene will continue to be a groundwater analyte. Therefore,
continued monitoring will determine whether cis-1,2-dichloroethene increases or decreases
in each EU.
37. Section 2.4.1 Northern Manufacturing Plant. Apparentiy, the COC selection process for
the northern manufacturing plant did not include data from monitoring wells P-2, P-6 and
P-7. The list of COCs selected for this area is potentially incomplete due to the exclusion
of these wells (see comment #21). Please revise the COC selection process to include
these wells.
October 11,2010
Response: Consistent with previous comment responses, the data sets for the northern
manufacturing area will be evaluated on an EU basis. The revised COPC selection process
will include the plume with wells P-2, P-6 and P-7.
38. Section 2.4.2 Plant 3 Water. Fork and Connor Springs, located south and southeast of the
contaminant plume at Plant 3, have been sampled a number of times in the past. No
contaminants have ever been detected in either spring. What does the groundwater model
predict for contaminant transport for this plume? Are Fork and Connor Springs expected
to remain unimpacted?
Response: Fork and Conner Springs are beyond the boundary of the DSHW-approved
model. They will be included in the risk assessment but are unimpacted by groundwater
constituents at ATK.
39. Section 2.4.3 Off-site Groundwater. Please demonstrate tiiat the volatile organic
compounds detected at a frequency of less than five percent are not part of a plume. If
these chemicals are dropped, how will these chemicals be addressed if detected in future
monitoring?
Response: Within the offsite groundwater data set, 1,2-dichloroethane, 4-methyl 2-
pentanone, benzene, and carbon tetrachloride were detected at a frequency of less than five
percent. 1,2-Dichloroethane had a maximum detected concentration of 2.2 //g/L, which is
greater than the risk-based screening level of 0.7 //g/L. 4-Methyl 2-pentanone and
benzene both had maximum detected concentrations that were less than both their risk-
based screening levels. Carbon tetrachloride had a maximum detected concentrafion of 1.5
//g/L, which is greater than the risk-based screening level of 0.5 //g/L.
Based on the March 11, 2010 meeting with the DSHW, the DSHW would like all detected
constituents included in the risk assessment process, even if they may be laboratory related
or of low detection frequency. The risk assessment will be revised to comply with this
request to the extent that the detected chemicals are site related. The inclusion of
chemicals unrelated to ATK's operations would lead to a risk assessment that is
misleading and detracts from the true constituents of concern.
40. Section 2.4.5 Off-site Sediment. Please include a discussion of the adequacy of sediment
data. A single sample from each spring does not seem adequate for characterizing
potential contamination. Please explain why volatile organic compounds were not target
analytes in the sediment but were in groundwater.
Response: There was only a limited data set available for soil and sediment from the
springs. Further, a complete analyte list was not available at the time the risk assessment
was prepared. Data adequacy for soil and sediments at each of the springs will be
discussed with the DSHW prior to the revision of the risk assessment.
41. Table 2-3 Groundwater Screening Levels for Promontory. The groundwater screening
levels do not meet the requirements of UAC R315-101. Specifically, ingestion, dermal,
19
October 11, 2010
inhalation and exposure to multiple contaminants needs to be considered. In addition, the
screening value for 1,1-dichloroethene should be verified.
Response: The RSLs address ingesfion and inhalation, however, the dermal pathway is not
addressed. The contribufion from dermal exposure is typically very small compared to the
other pathways. See also comment response number 33. It was agreed in the meeting with
the DSHW on Maich 11, 2010 that RSLs that do not include dermal exposure are
acceptable.
Screening levels can be calculated to address a combinafion of ingesfion, inhalation and
dermal, however, that would be very time intensive. The PRG of 1,800 //g/L (ingestion
only) for 1,1-dichloroethene (1,1-DCE) was confirmed and was obtained from the RSL
Tap water Supporfing Table. If DSHW meant 1,1-dichloroethane (1 ,l-DCA) instead, the
screening level of 3,700 //g/L was inadvertently transcribed, and should read 7,300 //g/L
(ingestion only). The handling of 1,1-DCA as a non-carcinogen is also discussed in
comment response 60.
42. Section 3.1.1 Groundwater. If groundwater is "essentially undrinkable," why is it used for
drinking water at Plant 3? The baseline risk assessment should be conducted assuming an
absence of institutional controls such as restriction on drinking water. ATK should
evaluate all offsite water as a potential drinking water source.
Response: The risk assessment will be revised to include off-site groundwater direct
exposure pathways and will assume that groundwater is not U'eated prior to consumption
regardless of its quality. Attachment A shows that the quality of groundwater is poor at
Promontory and its use for agricultural purposes is not recommended due to salt build up
that kills plants. It was agreed, based on this information that only direct exposure to
groundwater would be included in the risk assessment process for residential exposure.
Plant 3 groundwater is currentiy used for production water and fire fighfing and is not a
drinking water source due to the poor quality, and it is treated to remove TCE prior to use.
However, the risk assessment will assume groundwater use prior to treatment and after
treatment in different exposure scenarios.
43. Secfion 3.1.4 Sediment and Other Media. "The potenfial for other media to be impacted
by COCs will be identified in the risk assessment process." Where is this discussion?
"Where no data are available, exposure point concentrafions will be modeled or evaluated
qualitafively." Secfion 2.4.5 concludes that in the absence of VOC data, no comments can
be made without addifional data. There appears to be an absence of data, no modeling was
conducted, and no qualitative evaluation was presented. Please revise or clarify the text.
Response: There is a limited amount of sediment data available and the data was
insufficient for modeling. The need for additional data will be discussed with the DSHW
prior to starting the revised risk assessment.
20
October 11, 2010
44. Section 3.2.2 Off-Site Receptors. The purpose of the risk assessment is to provide
information to develop a site management plan. What are acceptable uses for the
contaminated groundwater? Does a restriction on groundwater need to be instituted? Can
the groundwater be used for all domestic uses or limited domestic use? ATK needs to
include an evaluation of ingestion and domestic use of groundwater.
Response: Off-site groundwater exceeds MCLs for a number of constituents at a number of
locations as indicated by the isocontour maps previously presented to the DSHW, and is
therefore unacceptable for domestic use. The revised risk assessment will assume
groundwater is used for all domestic purposes with the following direct exposure
pathways: ingestion, dermal contact and inhalation. The ingestion of vegetable and meat
from gardens and farms irrigated with contaminated water will not be included. The
results of the revised risk assessment will include a discussion of acceptable uses for
groundwater, and the risk estimates can be used to provide input to a site management
plan.
45. Section 3.2.2 Off-Site Receptors. ATK should include an evaluation of the homegrown
beef exposure pathway that does not assume an offsite fattening period as a potential
future exposure scenario.
Response: The text will be revised to clarify this point. As discussed in Section 3.4.4,
perchlorate uptake modeling assumed no loss of perchlorate from beef prior to
consumption due to fattening at a feedlof It also does not take into account the
demonstrated degradation of perchlorate in cattie.
46. Section 3.2.2 A Hypothetical Off-site Resident/Farmer. The text states that "the risk
assessment assumes a farmer would not use the groundwater for personal or agricultural
use because of the poor quality of this water." It is incorrect to make this assumption.
Groundwater to the west of the facility, near the drain field at M-153, has been used for
agricultural purposes in the past. In addifion, surface water flowing out of Shotgun Spring
has been used in the past for raising birds south of the facility. Perchlorate was detected in
this surface water at a concentration of 37.7 //g/L in April, 2005. Groundwater supplies
water for a trailer located in this area as well. The risk assessment needs to be revised to
account for these exposure pathways.
Response: An exposure unit approach will be taken, assuming the absence of administrative
and management controls. Each spring will be considered separately and consistent with
the prior risk assessment, agriculture use will be assumed at each of the springs.
47. Section 3.3 On-site Exposure Point Concentration. Multiple exposure point concentrations
may be needed to completely assess potential current exposures and potential future
exposures [UAC R315-101-5.2(b)(2)]. For instance, if higher volatile organic compound
concentrations exist in an area without current buildings, a potential future building should
be evaluated. A single average value for off-site and on-site groundwater is not likely
representative. For example, if well EW-6 is utilized for agricultural purposes, an average
off-site concentration would be far below what water from the well would contain.
21
October 11,2010
Response: See the response to comments 43 and 46. Table 1 shows the exposure units that
will be considered individually. Where buildings exist over groundwater shallower than
100 feet that contain VOC above the EPA's Vapor Intrusion Guidance Screening Levels
they will be considered for vapor intrusion. Site-specific parameters and building
dimensions will be used for each locafion individually. There are no residenfial buildings
off-site, and it will be assumed that a residenfial building is constructed over the highest
VOC concentrafion for the puipose of determining potenfial future impacts.
48. Section 3.3.2 Off-site vapor intrusion. The possibility exists that a residence could be
constructed over the contaminant plume neai" well EW-6. An average off-site
concentration (95 % UCL) could yield a lower exposure concentration than what has been
observed at well EW-6. In addition, the depth of groundwater at well EW-6 is
approximately 55 feet. What groundwater concentration and depth were used to estimate
the hypothetical, off-site indoor air concentration?
Response: As discussed with the DSHW, the depth to groundwater used off-site was deeper
than 55 feet. The revised risk assessment will use a location where the groundwater is
shallowest to represent the exposure point location.
49. Section 3.4.1 On-Site Commercial/Industrial Worker. It is stated in this section that "it will be
assumed that the adult commercial/industrial workers are not exposed to groundwater via
ingestion or dermal contact because workers do not contact groundwater on-site." Don't
workers at Plant 3 have dermal contact with contaminated groundwater at showers and
sinks at buildings M-201 and M-205? Please revise the text accordingly.
Response: The risk assessment used the acceptable perchlorate and TCE exposure point
concentrations developed assuming exposures that included dermal contact. The revised
risk assessment will calculate risks in a forward direction assuming exposure via ingestion,
dermal contact and inhalation while working and showering at Plant 3. Groundwater
concentrations will be used assuming no remediation is in place. Workers at Plant 3 have
dermal contact with contaminated groundwater at showers and sinks. The current and
future potential risks for that exposure will be evaluated in the revised risk assessment. As
discussed on page 41 of the risk assessment, goals have been calculated for exposure to
Plant 3 water. Those goals include exposure due to showering and inhalation.
50. Section 3.4.1 Inhalation Exposure. Why is it conservative to assume that 100 percent of
the chemical is retained by the lung? Where is this parameter in the equations? No
adjustment appears to be appropriate because the inhalation unit risk and reference
concentrations intrinsically account for lung absorption.
Response: The text will be revised to include a discussion of chemical lung retention. No
lung retention adjustment was used in the risk assessment.
51. Section 3.4.2 On-Site and Off-Site Construction Workers. Please explain why six feet
deep is judged too deep for a construction worker to contact groundwater. How deep are
existing foundations and utilities at ATK?
22
October 11,2010
Response: At ATK, construction activities deeper than six feet are unlikely. Buildings are
typically slab-on-grade construction and trenching deeper than six feet is rare and requires
special engineering controls.
Based on discussions with the DSHW, construction depths in the area of the points of
discharge of the springs near the ponds will be evaluated to determine if construction
would bring a worker in contact with groundwater at these locations.
52. Section 3.4.3 Off-site Environmental Worker. Please explain the parameter AT,
attenuation time in the equation.
Response: Within both the dermal absorbed dose equation on page 43 and Uie incidental
ingestion exposure equation on page 47, the parameter AT was incorrectly defined as
"attenuation" time. Instead it should read "averaging" time.
53. Section 3.4.4 Nearby Hypothetical Resident/Farmer Scenario. How can it be assumed that
an off-site hypothetical resident or farmer will not use contaminated groundwater for other
purposes such as watering a garden? The risk assessment needs to include potential
exposure pathways that are not under the control of ATK and determine if any restrictions
on groundwater use are warranted.
Response: Based on discussions with the DSHW on March 11, 2010 and the supporting
material in Attachment A of these responses, it will be assumed that off-site groundwater
is used for domestic use, but not for gardens or other agricultural purposes due to the high
TDS that exceeds the limits for crop watering. The exposure pathways will include
groundwater ingestion, dermal contact, vapor inhalation (showering and vapor intrusion).
It will be assumed that off-site groundwater is used by an off-site resident for domestic
exposures including ingestion, dermal contact and inhalation. The ingestion of vegetables
cultivated with potentially contaminated groundwater and the ingestion of animals raised
on potentially contaminated groundwater will not be considered.
54. Section 3.5 Future Projected Risks. Where are figures 3-2 and 3-3?
Response: Figures 3-2 and 3-3 were inadvertentiy omitted. They will be included in the
updated risk assessment.
55. Section 3.5.1 Northern Manufacturing Area. "In some cases the correlation between the
data and the model is poor, and therefore the model is a poor predictor of the current
concentration. Therefore, the future risks are likely to be overestimated. The current high
concentration of 6200 |ig/L was detected in 2008, the highest level the model predicts is
2960 [xg/L..." Please explain why the model under predicting current concentrations is
evidence that the model over predicts future concenfi-ations.
Response: The model has been recalibrated and the revised model approved by the DSHW.
The approved model will be used to better correlate with existing concentrations.
23
October 11,2010
56. Section 3.5.1, 3.5.2, and 3.5.3. Please justify the use of the arithmetic average for the
exposure point concentration. USEPA and the DSHW (UAC R315-1-1) recommend that a
conservative estimate of the mean (e.g., 95 percent upper confidence limit of the mean) be
used for the exposure point concentration.
Response: The arithmetic mean was used in the Northern Manufacturing Areas for future
exposure to represent average exposure. The groundwater model generated the data and
the arithmetic mean at 30 years for TCE was because the 95% UCL tends towards the
mean. Based on the comments provided here, the DSHW is requesting the use of the
maximum concentration in future Johnson-Ettinger modeling to calculate indoor air
concentrations. For the Central Manufacturing Area, where the data have a wide
variability between groundwater wells and are seen as inadequate, the approach to
evaluating groundwater in this area was discussed with the DSHW and it was agreed that
an exposure unit approach will be taken.
57. Section 3.5.4 Off-Site Surface Water. It is stated in this section that the current perchlorate
level in Pipe Spring is 234 //g/L. The modeled concentration for perchlorate in this spring
at year zero (the present) is 1,664 //g/L. Therefore, "future risk estimates will be seven-
fold too conservative." The model has been updated and recalibrated. The modeled
concentration for Pipe Spring has been changed. Please use the updated model to revise
the risk assessment as appropriate.
In addition, it was Shotgun Spring, not Pipe Spring that was used to evaluate the risk
associated with the recreational hunter exposure scenario. Please revise the text.
Response: The recalibrated model will be used to calculate the risks for Promontory.
Because the model affects all future potential exposures, the recalibrated model will be
used to estimate future risks for on-site exposure, including vapor intrusion, and off-site
exposure including residential exposure pathways at the Springs.
58. Section 4.0 Toxicity Assessment. In the table, please explain "Evaluated as a: Formerly
Potential carcinogen." Were cancer risks estimated for exposures to trichloroethene and
tetrachloroethene?
Response: The CSFs used in the risk assessment were obtained from US EPA's Regional
Screening Levels and the chemicals were evaluated a carcinogens. The table on page 53
will be revised and the "formerly potential carcinogen" will be changed to reflect the fact
that trichloroethene and tetrachloroethene were evaluated as potential carcinogens in the
risk assessment. As explained in the text in Section 4.1, the US EPA has withdrawn the
cancer slope factors (CSFs) from the Integrated Risk Information System (IRIS), and these
chemicals are undergoing review by the agency.
59. Section 4.0 Toxicity Assessment. "Of the six COCs found at Promontory perchlorate is
not considered, or at one time was considered potentially carcinogenic." Please revise this
sentence for clarity.
24
October 11, 2010
Response: The sentence will be revised to read "Of the six COCs found at Promontory,
perchlorate is the only one that will be evaluated as a non-carcinogen."
60. Section 4.1 Potentially Carcinogenic COCs. Please verify that the USEPA IRIS database
provides a cancer slope factor for 1,1-dichloroethane (1,1-DCA) as indicated in the text.
The USEPA-recommended PPRTV database has a cancer slope factor for 1,1-DCA and
the cancer risks should be quantified. Please provide a citation to support the statement
that the USEPA evaluates Class C carcinogens as non-carcinogens.
Response: The IRIS file for 1,1-DCA has no dose-response value listed. The October 2009
PPRTV tables indicate that the PPRTV has not developed a cancer dose-response values
for this chemical. Please provide the cancer slope factor for 1,1-DCA. The EPA's revised
cancer risk assessment guidance separates chemicals into classes and typically Class C
carcinogens, such as 1,1-DCE are evaluated as non-carcinogens.
61. Secfion 5.1.3 Plant 3 Beef Exposure Scenario. As stated in comment number ten, the risk
assessment should be conducted assuming a baseline condifion, i.e., an absence of
remediation, administrative, or engineering controls. The data used to evaluate risk should
be collected from before die wellhead treatment at Plant 3.
Response: See the response to comments 10 and 23.
62. Section 5.2.2 Hypothetical Off-Site Residential Exposure Scenario. Please see comment
numbers 48 and 53.
Response: See the response to comments 48 and 53.
63. Section 5.2.3 Hypotiietical Off-Site Trench Exposure Scenario. The same reasoning
regarding the use of an average groundwater concentration presented in comment number
48 applies to the evaluation of this scenario. How was the off-site TCE average
concentration calculated? Were future concentrations considered?
Response: Based on comments provided here for off-site exposure scenarios, it will be
assumed that exposure occurs at a point where groundwater VOC or perchlorate
concentrations are at a maximum. Although risk assessment guidance allows for the use
of the 95% UCL, the comment suggests this would be unacceptable for future potential
exposure.
64. Figure 2-2 COC Selection Process. The flow diagram has an unexplained route from
"Exceeds Background" to "Will Not Be Considered A COC." Please clarify.
Response: Figure 2-2 is a direct reproduction of EPA Region 8's COC selection process. A
revised COC selection process was discussed with the DSHW and the COPC selection
process will not include the detection frequency screen, even though it is used by EPA
Region VIII.
25
October 11,2010
65. Figure 2-2 COC Selection Process. UAC R315-101 is risk-based. A technology-based
MCL is not an appropriate screen for the risk assessment. Please revise.
Response: See the response to comment 64. Figure 2-2 will be revised to remove the
technology-based screen, following discussions with the DSHW.
66. Figure 3-1 Conceptual Site Model. The model appears to consider only current exposures.
Please revise to include potential future exposures to meet the requirements of UAC R315-
101-5.2(b)(2).
Response: Separate conceptual site models will be provided that show future potential
exposure pathways. As noted in the above comments and responses these will include
exposure to groundwater off-site assuming no institutional controls and potable water use
at the point of 95% UCL contaminant concentration off-site for wells that make up the
contaminant concentrations within that plume.
67. Table 2-4 Constituents of Concern Screening for On-Site Groundwater at Promontory.
Please define Regulatory COC.
Response: The text will be modified. No regulatory screening levels will be used.
68. Table 3-9 Please identify the sources, and rationale if appropriate, of all parameters.
Response: See the response to comment 77.The table will be revised to provide the source
and rationale for each of the parameters in the table.
69. Appendix 2-1-5 On-Site Groundwater Summary Statistics. The table title is "Summary
Statistics for Raw Data Sets with NDs using Detected Data Only." The titie appears to be
contradictory. Please clarify if the results of this table include non-detects. Please define
all table acronyms and abbreviafions.
Response: The summary stafistics for the table in question includes only detected data. The
acronyms and abbreviations used in the table were generated in ProUCL and will be
defined in the revised risk assessment.
70. Please provide an explanafion of how the results of the outiier tests were interpreted.
Please note that by definition, contamination is often identified as outiiers.
Response: No outiying data were removed from the dataset. Outiiers were calculated for
information only.
71. Appendix 3 Future Projected Groundwater COC Concentrations. The exposure point
concenfi-ation was based on the arithmetic average at year 30. Why wouldn't a 95 percent
upper confidence limit be calculated? Why is the concentration at year 30 representative
of the concentrations between now and year 30?
26
October 11,2010
Response: Based on the revised approach, for each of the identified plumes in Table 1, the
future projected 30-year 95%UCL groundwater COPC concentration will be esfimated by
calculating the 95% UCL concentration for each year for the identified groundwater wells,
and the 95% UCL for each year will then be used to calculate a 95%UCL concentration to
represent 30 years of exposure to groundwater for that COC plume. This concentration
will be used to model vapor intrusion and other worker exposures on-site and the domestic
residential exposure pathways for off-site exposure.
72. Appendix 2-2. The Central Manufacturing Area has only three observations for some
COCs. Why is the data adequate?
Response: Three observations is a limited data set for risk assessment and not an adequate
data set. The issue of data adequacy for each EU will be evaluated in the revised risk
assessment.
73. Appendix 3, p. 5, Building Conditions. The text indicates that floor thickness was 0.5 feet
but Table 3-2-1 lists 1.0 feet. Please reconcile.
Response: The text will be resolved. Typical slab thickness in the manufacturing areas at
Promontory is 0.5 feet and future modeling will use this value.
74. Appendix 3, Building Conditions. Please justify the use of the high end of the range for
indoor air exchange rate.
Response: The Johnson-Ettinger model and indoor air exchange rates are generally based
on residences, which are generally well insulated and designed to retain heat. The high
end of the air exchange rate was used because industrial buildings are generally less well-
insulated and more permeable to air infiltrafion. The buildings at Promontory are
industrial slab-on-grade construction and have more openings than residential buildings
and therefore would have a higher air exchange rate. No air exchange rate studies were
conducted at Promontory.
75. Appendix 3, Building Conditions. How sensitive is the model to the assumption of 20-foot
ceilings?
Response: The Johnson Ettinger model is sensitive to both the size of the room into which
vapors are moving and the number of air exchanges within the room. The larger the
dimension of a room the greater its ability to disperse contaminant vapors. The building
dimensions were based on actual conditions at the facility. A sensitivity analysis of the
ceiling height, and other Johnson-Ettinger model parameters will be provided in
subsequent analyses. However, the Johnson-Ettinger model "User's Guide for Evaluating
Subsurface Vapor Intrusion into Buildings, (EPA Office of Emergency Response and
Remedial Response, February 2004) provides a summary of the sensitivities in the model.
76. Appendix 3-3 Modeling Scenarios. In the last paragraph, it is stated that only one
groundwater depth was used which was consistent with the depth to groundwater in the
northern manufacturing area (120 feet). Groundwater depth is not shallowest in this area
27
October 11,2010
as stated. The groundwater depth at well G-2 is approximately 60 feet (one-half the depth
used). Furthermore, the projected TCE concentration at well G-2 is 2,197 //g/L at year 30.
Based on these factors, risk calculations in regard to exposure to vapor should be reviewed
and revised as needed.
Response: Trench vapor modeling will be conducted for each exposure unit as agreed with
the DSHW. However, the areas with the highest potential for vapor intrusion into a trench
are the areas where groundwater is shallow and that coincide with the shallowest depth to
groundwater. These areas are near where groundwater forms a spring. They will be
included in the revised risk assessment.
77. Appendix 4. Please provide an explanation and references for the beef parameters. For
instance, what is the source of the cattie water consumption?
Response: Mr. Paul Hancock previously submitted tiie beef consumption model used in the
risk assessment to the DSHW in 2003 in correspondence to Mr. Dennis Downs. This
correspondence and its associated references are provided in Appendix 4 of the risk
assessment. As described in Section 5.1.3, the assumption is that cattie are only watered
with water from Pipe springs (the highest perchlorate value of the springs).
As agreed at the meeting with the DSHW on March 11, 2010, the use of incineration
models, which are designed to model hydrophobic compounds like dioxin, are
inappropriate for perchlorate uptake.
28
October 11, 2010
CITATIONS
Burrows etal., 1989;
Monteil-Rivera et ai, 2003
Spanggord etal., 1982)
Rosenblatt, etal. 1991
EPA 1988
29
October 11, 2010
StfUlFAX BlVfAM-ftXig. IK-.
PLATE 1
A^K PRCMONfC'''
SHr MAP. SOUNOAJ^Y. AND
30
October 11,2010
Plate 2: Groundwater Wells Less than 100 Feet
I
r-
DRUM STORAGE AREA
AREA (TCE) —.
C-7
M153
DRAINFIELD
(CL04 AND TCE)
H-4
H-3
H.2
BC-3
E519 LABORATORY SUMP
(PERCHLORATE AND TCE)
p-7 S' P-6
P-2
.M()?.()i51
E585 LABORATORY SUMP
(PERCHLORATE, DCE, AND TCE)
BUILDING 115 WASHOUTi
(PERCHLORATE)
I
i
M136 BURNING GROUNDS '
(PERCHLORATE. TCE AND TCA) .
I
PERCHED AQUIFER
(PERCHLORATE, TCE AND TCA)
..E-4
\
E-S \
•.E-6
I{-6 \,
\
PROMONTORY BC-4
BC* '0-3
G-4 *-5
.J-6
SHOTGUN SPRING^ ^PlPf5PRING
G-6
EW-3
BC-5
H-9
ATK FACILITY BOUNDARY
I L.._.
PLANT 3
(TCE)
l_.
EW-1
FISH SPRING
HORSE SPRING A JO
H-10
H-IO •
H-10 •
H-10 •
AT< FACI'J'V BOUNDARv
EXTENT OF CONTAMINATION l\ PERCHED AOUiEER
EXTENT CE CONTAMINATION IN UPPERMOST AQUlEER
NCLJOES VOCS AND PERCHLORATE
WELL < 100 TEEI 10 GROUNDWATER (VIlH ICE/OCt BELOW SCREENING LEVEL
WELL < 100 FEET to GROUNDWATER WHERE ICF EXCEEDS SCREENING LEVEL OF 6 UQ/L
WELL < 100 lEEI 10 CROoNDWAIER WHERE DCE EXCttCS SCREENING LEVEL 0> 190 ug/L
|Rfl| RartbPuc Enfjneerinf. Inc. |Rfl| RartbPuc Enfjneerinf. Inc.
EwthPax
MONITORING WELLS WITH A DEPTH TO WATER LESS THAN 100 FEET
EwthPax
MONITORING WELLS WITH A DEPTH TO WATER LESS THAN 100 FEET
EwthPax
MONITORING WELLS WITH A DEPTH TO WATER LESS THAN 100 FEET
EwthPax
MONITORING WELLS WITH A DEPTH TO WATER LESS THAN 100 FEET
EwthPax
MONITORING WELLS WITH A DEPTH TO WATER LESS THAN 100 FEET
EwthPax
MONITORING WELLS WITH A DEPTH TO WATER LESS THAN 100 FEET
EwthPax
MONITORING WELLS WITH A DEPTH TO WATER LESS THAN 100 FEET
EwthPax
MONITORING WELLS WITH A DEPTH TO WATER LESS THAN 100 FEET
ATK LAUNCH SYSTEMS INC. ATK LAUNCH SYSTEMS INC. ATK LAUNCH SYSTEMS INC.
1
31
October 11,2010
REVIEW OF THE COMMENTS PREPARED BY
THE UTAH DIVISION OF SOLID AND HAZARODUS WASTE ON THE
DRAFT HUMAN HEALTH RISK ASSESSMENT FOR GROUNDWATER AT
THE ATK LAUNCH SYSTEMS, PROMONTORY FACILITY, PROMONTORY, UTAH
ADDITIONAL COMMENTS
Additional Comment 1. Constituent of Concern (COC) Selection Process: Section 2.3, COC
Selection Process, discusses the screening criteria used to determine COCs. Please
address the following:
Comment On-site (including Plant 3 Water) and Off-site Groundwater
Based on a review of the data screening tables (Tables 2-4 and 2-5), compounds exceeding
maximum contaminant levels (MCLs) are designated as "regulatory COCs" and
compounds exceeding groundwater screening levels (GWSLs, based on "ingestion only"
Regional Preliminary Remediation Goals [PRCs]) are noted as "COCs." While, Section
2.3, COC Selection Process, notes that GWSLs will be taken from the EPA September
2008 Regional Screening Levels (RSLs) for tap water, this appears to be a slight
contradiction.
Regardless, please use the EPA RSLs for tap water to screen compounds for chemicals of
potential concern (COPCs). EPA RSLs for carcinogenic compounds should be used as
published, however, the EPA RSLs for non-carcinogenic compounds should be adjusted
downward by a factor of 0.1 to account for additive effects. Any compounds exceeding
their respective RSL should be selected as a COPC and carried forward in the quantitative
assessment and discussed in the risk characterization section. Also, please note that the
EPA RSLs were updated in December 2009 and may be accessed at:
http://www.epa.gov/reg3hwmd/risk/human/rb-
concentration table/Generic Tables/pdf/master si table run DECEMBER2009.pdf. The
COPCs associated with elevated levels of risk or hazard should be designated as COCs and
addressed within the context of corrective action documents such as Corrective Measures
Study (CMS) or Feasibility Study (FS)-type documents. MCLs may be considered
compliance or enforcement standards within the context of a CMS, but are not appropriate
for use as initial screening criteria where multiple complete exposures pathways occur for
a given receptor population. The MCLs do not have a consistent health basis (within their
own paradigm or in comparison to other USEPA-promulgated health-based screening
criteria for drinking water such as the Tap Water RSLs) and are mediated by treatment
technology and economic constraints. Use of the Safe Drinking Water Act (SOWA)
MCLs as screening criteria will not yield a defensible basis for a baseline risk assessment
- which often differs from an assessment targeting remedial standards.
Response: The EPA's 2009 RSL will be used for screening the data for each exposure area.
However, the use of the maximum concentration with the non-cancer RSL/10 is a
conservative approach that will potentially include COPC that will not significantiy
contribute to the Hazard Index.
Comment Off-site Surface Water
32
October 11,2010
Surface water may be screened by adjusting the EPA tap water RSL upward (less
conservative/protective) by a factor of 10 if offsite surface water is not used as a drinking
water source. To evaluate additive effects, the RSLs for noncarcinogens would not be
adjusted and would be used as published. Another approach is to screen surface water
concentrations against National Recommended Ambient Water Quality Criteria (AWQC)
based on Human Health Consumption of Organisms Only, if viable fish or shellfish
populations are present in off-site surface water.
Response: Please see the previous response. ATK does not believe that there are viable fish
or shellfish populations in the Ponds.
Comment Off-site Sediment
December 2009 EPA RSLs for residential soil should be used to screen off-site sediment.
Again, EPA RSLs for carcinogenic compounds should be used as published, however, the
EPA RSLs for non-carcinogenic compounds should be adjusted downward by a factor of
0.1 to account for additive effects. Any compounds exceeding their respective RSL should
be selected as a COC and evaluated quantitatively in the risk assessment. As a reminder, it
is important to use screening values predicated on residential exposure to evaluate baseline
conditions, which is necessary to become fully informed about site exposures and form the
basis for appropriate risk management decisions.
Response: ATK will screen sediment as soil. This is an extremely conservative approach as
the potential contact with sediments is significantiy lower than the exposure levels
assumed for soil, even the Industrial/Commercial RSL.
Comment Vapor Intrusion
It is also important to clarify that compounds to be evaluated in the vapor intrusion (VI)
assessment should not be selected based on a comparison of EPA RSLs to groundwater
concentrations. EPA RSLs do not take into account indirect exposures (e.g., VI). COCs to
be evaluated for the VI pathway should be selected differently and this issue is further
discussed in Comment 3 - Vapor Intrusion.
Response: Please see the previous response to the DSHW comments, and Additional
Comment #3 below.
Comment Terminology
Further, it is recommended that the draft HHRA be revised to discuss chemicals exceeding
applicable risk-based screening levels as chemicals of potential concern (COPCs) rather
than COCs, as COCs are often discussed as chemicals known to be risk-drivers and
addressed as targets of remediation efforts.
Response: The term COPC will be used in the risk assessment process.
Additional Comment 2. Calculation of the 95% Upper Confidence Limit (UCL) on the
mean: The draft HHRA notes that ProUCL Version 4.00.02 was used to calculate the 95%
upper confidence limits (UCLs) on the mean. However, please note that ProUCL Version
4.00.04 dated February 2009 supersedes ProUCL Version 4.00.02. If possible, revise the
33
October 11,2010
draft HHRA to use ProUCL Version 4.00.04 in determining exposure point concenti-ations
(EPCs) based on 95% UCLs. If this step will result in excessive reworking of existing
data compilations, please address the issues associated with the use of a dated software
version within the context of the uncertainty analysis.
Response: The 95% UCLs will be recalculated using ProUCL Version 4.00.05 (May 2010).
However, this change is unlikely to significantiy change the 95% UCL because the same
statistical approach is used in each version of the program.
Additional Comment 3. Vapor Intrusion: The draft HHRA relies heavily on the Johnson and
Ettinger (JEM) model to predict indoor air concentrations based on underlying
groundwater concentrations. These modeled indoor air concentrations are used by ATK to
demonsti^ate whether potential VI constitutes an indoor air concern. While the JEM may
be used to support the need for a vapor intrusion assessment, where groundwater screening
criteria are exceeded, the administrative authorities do not support the use of the JEM to
prove the negative - that is, the JEM is not defensible as a single line of evidence to
disprove VI potential where groundwater exceedances have been recorded.
Over the last ten years, empirical evidence collected and evaluated by U.S. EPA strongly
suggests that application of the JEM at individual buildings in a defensible determination
of site-specific subsurface-to-indoor air attenuation factors is impracticable and unreliable
for most sites. In recognition of this, U.S. EPA does not support the use of the JEM as a
single line of evidence in a deterministic assessment of the potential for VI and has
gravitated toward an ever increasing need for the collection of empirical data to assess VI
potential along with the implementation of institutional controls to mitigate exposure
where the vapor intrusion pathway may be complete.
Since 2002 and the release of U.S. EPA's VI Guidance, there have been substantive
improvements in the understanding of the science underpinning VI phenomena and the
investigative methods to assess it. U.S. EPA has been actively engaged in the collection of
additional observations from VI sites across the U.S. to improve our knowledge and
understanding of VI, and in particular, the attenuation of vapors between the subsurface
and indoor air.
The spatial and temporal variability in observed subsurface and indoor air concentrations
among and within buildings means that for every site and every structure at a site, a range
of empirical (i.e., measured) attenuation factors would likely be calculated from a series of
discrete indoor air and subsurface vapor concentrations measured at different points in
space or at different times. This variability may be due to: 1) vertical and horizontal
differences in subsurface conditions; 2) differences in building structural conditions, such
as foundation cracks and ventilation rates; and, 3) weather conditions, such as precipitation
influence and barometi"ic pressure. Considering this variability, a statistical approach to
characterizing the empirical attenuation factors was adopted in the 2002 VI Guidance.
Shortiy after the 2002 Draft VI Guidance was released, U.S. EPA initiated efforts to
improve the 2002 vapor intrusion database by adding sites and additional site-related
34
October 11, 2010
information to better represent VI in a broader cross-section of the U.S. The compiled
database is presented in "U.S. EPA's Vapor Intrusion Database: Preliminary Evaluation of
Attenuation Factors" (2008 Database) (U.S. EPA 2008).
Once a volatile constituent source has been identified in the subsurface (roughly within
100 feet laterally or vertically of an exposure point [i.e., current or proposed building]), the
VI pathway is assumed to be complete. To determine if the pathway is significant from a
human health perspective (and thus requiring additional scrutiny in the form of a Tier 3
assessment, additional data collection, or implementation of vapor intrusion mitigation
controls), detected concentrations in groundwater or soil gas should be compared to the
lE-06-based screening criteria presented in Table 2c of U.S. EPA, 2002. The procedures
outiined in the 2002 VI Guidance are designed (and should only be used) to help site
managers identify which structures in a given area are likely to be representative of the
"worst case" condition, leading to selection of these locations for direct measurement of
(typically) subslab soil gas data and indoor air data (exposure point assessment).
Default attenuation factors utilized in the 2002 VI Guidance and associated vapor intrusion
screening criteria are presented below:
> Groundwater-to-Indoor-Air Attenuation Factors: For the purposes of initial
risk screening of the vapor intrusion pathway based on groundwater data, a
groundwater-to-indoor air attenuation factor of 0.001 is recommended by U.S.
EPA.
> Soil-Gas-to-Indoor-Air Attenuation Factors: For the purposes of initial risk
screening of the vapor intrusion pathway based on soil gas data, a soil gas-to-
indoor air attenuation factor of 0.01 is recommended by U.S. EPA.
> Subslab-to-Indoor-Air Attenuation Factors: For the purposes of initial risk
screening of subslab soil gas data, a subslab soil gas-to-indoor air attenuation factor
of 0.1 is recommended by U.S. EPA.
I. Selection of Screening Criteria: Although the VI database and the parameters used
in development of the Table 2c screening criteria have a significant focus on
residential exposures, these criteria are appropriate for use in initial screening
regardless of land use (i.e., commercial/industrial).
II. Comparison of Site Data to Screening Criteria: Groundwater or soil gas data
from multiple exposure points within a defined area or exposure unit may be
compared to the screening values listed in U.S. EPA 2002 VI Guidance, Table 2c. As
an alternative, recorded measurements may also be compared to the gross
characterizations graphically outiined in Figures 3a and 3b of the VI Guidance. The
only appropriate adjustment that should be incorporated into these screening values
is where there has been a federally-published update to the toxicity criteria used to
develop these numbers (e.g., U.S. EPA's desire to base trichloroethylene exposures
on CalEPA-published toxicity criteria in preference to the NCEA 2001 values
originally used in the 2002 VI Guidance). Alternatively, and based on prior
agreement with UDSHW, the Table 2b (target risk = lE-05) may be considered for
use in screening on-site VI exposures.
3.S
October 11,2010
HI. Exceedance of the Screening Criteria: If exceedances of the screening criteria are
recorded, this indicates the need for additional scrutiny and multiple lines of
(converging) evidence.
IV. Identification of "Indicator Buildings": A "Tier 3 " (see VI guidance, 2002), site-
specific VI assessment utilizing the JEM may be conducted to identify the "indicator
buildings" for additional direct measurement/monitoring (i.e., those buildings likely
to be representative of "worst case" conditions).
o Site-specific application (the Tier 3 assessment) utilizing the JEM cannot be
utilized to screen-out locations from further assessment (where VOC
detections in environmental media exceed the Table 2 c screening criteria).
JEM-based predictive modeling results are subject to significant
uncertainties. Therefore, direct measurements are required if screening
criteria are exceeded.
V. Need for Additional Data - Indicator Buildings: If groundwater or soil gas
exceedances are indicated, collection of synoptic (i.e., paired measurements) subslab
soil gas and indoor air data are required at the "indicator buildings."
VI. Undeveloped Areas Lacking IC/LUCs to Preclude Development: If an
undeveloped area is within the zone of concern for lateral and vertical distance from
a vapor source, and if screening criteria are exceeded in the undeveloped area, site-
specific application of the JEM model alone cannot be used to screen out future
potential VI susceptibility. In this case, proper legally enforceable and transferable
institutional and land use controls (ICs/LUCs) are required to ensure building
construction considers proper vapor intrusion mitigation controls. Such IC/LUCs
must stipulate on-going subslab soil gas and indoor air testing prior to occupancy and
continued monitoring at appropriate intervals to ensure VI mitigation controls do not
become compromised.
VII. NAPL Considerations: The risk-based screening criteria presented by U.S. EPA in
the VI Guidance (Table 2c) are not to be used when free product is present. The
mere presence of non-aqueous phase liquids in proximity to occupied buildings
requires direct measurement of soil gas at the interface with a building (subslab soil
gas) and exposure point (indoor air monitoring). [Note: U.S. EPA has previously
employed methodologies to derive an estimate of the potential for off-gas sing from
subsurface sources represented by free product mixtures (i.e., Raoult's Law);
however, because of complex and unpredictable equ ilibrium partitioning phenomena
associated with the behavior of free product in the subsurface, U.S. EPA does not
currently support the use of free product concentrations in the derivation of sub-slab
soil gas or indoor air concentrations for the purposes of VI potential assessment.
Direct measurement of conditions at the interface with an overlying building (i.e.,
sub-slab soil gas) and the indoor air are indicated when free product is present
within a zone capable of impacting an exposure point (e.g., building indoor air).]
VIII. Bulk Soil Data Considerations: Bulk soil data may not be used as the basis for the
VI assessment.' U.S. EPA has not presented screening criteria for use in assessing
bulk soil data and has contraindicated the use of bulk soil data in a quantitative
assessment of VI potential. The analytical results from soil matrix samples are
' Note, however, if a NAPL source is suspected, a soil sample may be necessary to determine whether a NAPL source
is present. Also, bulk soil concentration data could be used in a qualitative sense for delineation of sources, where
appropriate.
36
October 11,2010
biased low due to vapor loss as indicated by U.S. EPA in SW-846 for Method
5035A". Likewise, soil gas results obtained from soil matrix samples are subject to
uncertainty due to the assumptions underpinning contaminant partitioning.
IX. Data Needs to Support Risk Management Decisions for Vapor Intrusion:
Defensible site- and risk-management decisions must be based on multiple lines of
evidence. No single medium data set (groundwater, soil- or subslab vapor) is
sufficientiy reliable for evaluating VI potential,
o For sites where environmental media concentrations indicate an exceedance of the
screening criteria provided in Table 2c of the 2002 VI Guidance, single lines of
evidence are no longer appropriate,
o Examples:
• Where groundwater concentrations exceed the Table 2c screening criteria,
collection of either sub-slab soil gas or indoor air is not sufficient for risk
management decisions. Both are required in this case.
• An acceptable combination of multiple lines of evidence includes the
implementation of a soil gas mitigation program and the collection of
indoor air samples.
o The most informative set of multiple lines of evidence includes an assessment of
indoor air coupled with subslab soil gas data.
Response: The approach required to evaluate vapor intrusion has not be raised by the DSHW
before. Based on these comments, ATK will evaluate vapor intrusion for buildings located
over groundwater shallower than 100 feet, and within 100 feet laterally of volatile organic
compounds in groundwater (See Plate 2 above). Screening levels from the EPA's 2002
Vapor Intrusion (VI) Guidance are residential and conservative for on-site
industrial/commercial workers who are potentially exposed for 8 hours not 24 hours. The
DSHW agreed the acceptable excess lifetime cancer risk level for vapor intrusion is one in
one hundred thousand (IxlO'^) with ATK, which would make Table 2b of the EPA's 2002
VI Guidance the appropriate table of screening criteria, as modified for industrial workers.
Further, Table 2b provides a groundwater-screening level for TCE that is based on an
Inhalation Unit Risk value derived from the EPA's 2001 NCEA draft toxicological profile
that has been rejected by EPA. The lUR value developed by Cal EPA is recommended for
the development of VI screening at Promontory. ATK has concerns about embarking on
an extensive vapor intrusion assessment program when the majority of the volatile
compounds in groundwater are deeper than 100 feet, and VI modeling indicates that VI is
of low concern. ATK agrees that a "line-of-evidence" approach is important. However,
before ATK undertakes a significant field program they propose to conduct screening that
identifies candidate buildings that may be impacted (a building over groundwater
shallower than 100 feet containing volatile chemicals and for which the Johnson-Ettinger
model would predict the highest indoor air concentrations).
Additional Comment 4. Exposure Factors: While many of the exposure factors were
appropriately obtained from applicable guidance documents, several exposure factors are
" This concern may be somewhat minimized through the proper collection of samples; however, an increase in the
accuracy of sample collection cannot overcome other uncertainties associated with the use of bulk soil data in a VI
potential assessment.
37
October 11,2010
not consistent with administrative authority guidance and require additional justification.
Please revise the draft HHRA to address the following:
• An exposure frequency (EF) of 50 days/year and an exposure duration (ED) of 25 years
were used to evaluate a construction worker during trench exposure. Please revise the
HHRA to provide the complete decision rationale for selecting an exposure frequency (EF)
of 50 days/year as EPA recommends a minimum EF of 90 days/year for one year for this
receptor.
• An EF of 2 days/year and an ED of 25 years were used to evaluate environmental workers.
However, it is unclear whether 2 day/year is representative of how often environmental
workers encounter the site. Please provide further rationale for using an EF of 2 days/year
to evaluate this receptor.
• Any dermal exposures that need to be quantified should utilize appropriate reasonable
maximum exposure (RME) skin surface areas and adherence factors established in Risk
Assessment Guidance for Superfund [RAGS], Volume I: Human Health Evaluation
Manual, Part E, Supplemental Guidance for Dermal Risk Assessment dated July 2004.
• Inhalation rates used to quantify inhalation risk and hazard should be proved.
• Ensure that all previous comments provided by Utah DSHW on the exposure factors are
thoroughly addressed (e.g., regarding hunter exposures).
• Please improve the overall organization of how the risk assessment information and
exposure factors are presented. Specifically, please address Additional Comment 5 - Draft
HHRA Presentation and Organization (below).
Response: Additional information will be provided to justify the exposure assumptions used
in the risk assessment.
Additional Comment 5. Draft HHRA Presentation and Organization: The organization of
the overall Draft HHRA and the presentation of risk assessment information could be
improved. Also, while equations are generally presented in the Draft HHRA, exposure
pathways and associated equations and specific input parameters should be provided
within appropriate reporting tables as consistent with RAGS, Volume I: Human Health
Evaluation Manual, Part D, Standardized Planning, Reporting, and Review of Superfund
Risk Assessments (RAGS Part D). Please refer to RAGS Part D and revise the Draft
HHRA to improve presentation and organization of the risk assessment approach, and
ensure that the specific equations and all input parameter values are also presented in the
formats provided/offered in RAGS Part D (i.e., please note that RAGS Part D provides
example risk assessment reporting tables and instructions for completing reporting tables,
which should be followed when preparing the revised HHRA). Please revise the Draft
HHRA accordingly and reference RAGS Part D appropriately.
Response: EPA's RAGS Part D format produces a document with a significant level of
redundancy and duplication in the documentation, the risk assessment will be revised to
incorporate the essence of RAGS Part D, but may combine EUs to reduce redundancy.
Additional Comment 6. General Note. Please ensure that ATK also addresses all 77 comments
previously submitted by Utah DSHW.
38
October 11, 2010
Response: Please see above.
39
October 11,2010
SUPPLEMENTAL INPUT PREPARED FOR
THE UTAH DIVISION OF SOLID AND HAZARODUS WASTE ON THE
DRAFT HUMAN HEALTH RISK ASSESSMENT FOR GROUNDWATER AT
THE ATK LAUNCH SYSTEMS, PROMONTORY FACILITY, PROMONTORY, UTAH
COMMENTS:
General Comment 3. Additionally, please note new Additional Comment 3.
Response. Please see above
Specific Comment 4. 2"'' Paragraph: Exposure units should be clearly presented. Data collected
from source wells within each exposure unit should be used to determine exposure point
concentrations (EPCs). The EPCs should be the maximum detected concentration (MDC)
for each chemical of potential concern (COPC) or the 95% upper confidence limit (UCL)
on the mean. Note, however, that Utah DSHW acknowledges that certain wells may not
be most indicative of the highest concentrations of certain leading edge COPCs, or
breakdown products (e.g., highly mobile products like vinyl chloride [VC]). Further,
"key" peripheral wells are helpful to understand the extent of the groundwater plumes, but
the human health risk assessment (HHRA) should use data representative of the center of
the plumes.
Response. A map, similar to that shown in Plate 1, will be provided to clearly indicate each
EU plume, and the selection of COPC process will be undertaken for each EU. The nature
and extent of COPC in groundwater will evaluate the plume over time and determine
potential breakdown products and concentrations representative of the average
groundwater concentration.
Specific Comment 7. f*' Paragraph: Inorganics must not be eliminated from the quantitative
assessment on the basis of background. All inorganics that exceed applicable risk-based
screening criteria should be carried forward in the risk assessment. The uncertainty
analysis may then include a refinement of the total risk by expressing total risk as
background risk and site-related risk. Please ensure that all risks and hazards are
quantified for all inorganics that exceed applicable risk-based screening criteria.
Response. As noted above, the risk assessment will include the required analysis in the
uncertainty section of the report.
Specific Comment 10. Please note that pre-treatment conditions should be evaluated in the
HHRA as this forms the demonstrated need for treatment. However, post-treatment
conditions may be included in the HHRA as being representative of current site conditions
(with pre-treatment conditions considered as future potential - in the event that ti-eatment
is discontinued). Please ensure that exposure scenarios representative of pre- and post-
treatment conditions are both included in die HHRA.
Response. Where current conditions include ti-eatment or remediation, both pre- and post-
remediation conditions will be evaluated in die HHRA.
40
October 11,2010
Specific Comment 13. The four springs should be evaluated separately (i.e., each spring should
be evaluated as an individual exposure unit). Also, please clarify if other recreational
users besides recreating hunters frequent or encounter these springs (i.e., are these springs
"attractive nuisances?").
Response. All of the ponds and springs (Pipe Springs, Shotgun Springs, Horse Springs, Fish
Springs, Conner Springs and Fork Springs) will be evaluated separately. Recreational
activities were identified by ATK workers, who are familiar with recreational use at the
springs; additional work will be undertaken to ensure that other receptors are considered.
Specific Comment 15. Arsenic should not be eliminated from the quantitative risk assessment if
arsenic exceeds its respective risk-based screening criterion (e.g., EPA Regional Screening
Level).
Response. Arsenic will be evaluated in the uncertainty section of the HHRA.
Specific Comment 24. In addition, please note that background should be established as the 95%
upper tolerance limit (UTL) (or possibly the mean plus two standard deviations, as
representative of 90 to 95'^ percentile).
Response. Comment noted.
Specific Comment 25. Please note that sample quantitation limits (SQLs) are more critical than
DLs. Please clarify whether SQLs are sufficient to meet screening needs with respect to
applicable risk-based screening criteria. Where Utah DSHW has previously commented
about DL concerns, please consider SQLs (e.g.. Specific Comment 29, 31, etc.) as the
preferred metric - especially in regard to the assessment of non-detect results.
Response. Please see previous responses. Although the SQL is more accurate than the DL,
ATK believes the DL is an adequate metric to select COPC and guidance allows its use
when calculating the 95% UCL that will be used in the risk assessment.
Specific Comment 27. Also, please refer to EPA's Guidance for Comparing Background and
Chemical Concentrations in Soil for CERCLA Sites dated September 2002.
Response. Comment noted, the HHRA will refer to the 2002 guidance.
Specific Comment 31. Please clarify reporting limit bases (the SQL/practical quantitation limit
(PQL) preferred).
Response. In general the DL was used in the HHRA.
Specific Comment 34. Please refer to Additional Comment 5.
Response. Comment noted.
41
October 11,2010
Specific Comment 45. Please clarify whether off-site cattie are watered with contaminated
groundwater, fed with crops irrigated with contaminated groundwater, and whether any
COPCs in groundwater are bioaccumulative.
Response. Cattie were watered for a limited period of time with perchlorate-contaminated
water from Plant 3. They were fed with grass that was not irrigated with contaminated
water, but it was assumed that beef cattie were fed with perchlorate-contaminated grass,
and the cattie were not fattened before slaughter. No other bioaccumulative constituents
are present in groundwater near Plant 3.
Specific Comment 52. "AT" appears to mean averaging time. Please resolve this discrepancy.
Response. AT means averaging time.
Specific Comment 69. Also, please indicate how many non-detect results were associated with
elevated SQLs relative to the most pertinent health-based screening criteria.
Response. Non-detect chemical levels at the DL and EQL will be evaluated against the RSL,
the results will be provided in the uncertainty section.
Specific Comment 71. Additionally, please consider using concentrations at the center of the
plume for evaluating future concentrations.
Response. Future constituent concentrations will be calculated from the DSHW-approved
groundwater model for each EU.
Specific Comment 77. Also, please note that beef parameters may be obtained from EPA's
Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities
Companion Database dated September 2005.
Response. The guidance cited is for hydrophobic constituents, such as dioxin. The primary
constituent at Promontory, perchlorate, is hydrophilic and the incineration guidance does
not apply.
42
October 11, 2010
ATTACHMENT A: METALS CONCENTRATION IN SURFACE WATER AND
GROUNDWATER AT PROMONTORY
A.l Arsenic Surface Water Concentrations
Ta
Blue Creek
(Prior to en
ble 1
Arsenic Data
tering facility)
Sampling Date Sample Result
(//g/L)
2/4/10 U(<10)
10/6/09 25.8
7/15/09 34
4/16/09 30.2
2/1 1/09 35.8
5/2/08 148
7/1/08 U(<500)
10/9/08 30.3
1/12/07 37
4/3/07 25
7/12/07 58
10/8/07 49
43
REVISED DRAFI
A.2 Arsenic Groundwater Concentrations
June 21, 2010
BC-3
.2.
• LM P-8
• M508.4 • pg
P-6
23 P-7. P-2
92
LF-U
538> .LF-2 .M636B1
i LF-3
1
.C-6 432 A-9
241
.C-7
3380
E-1
1330
.H-8
H.7
1-2 60S O
365
H-4
11.3
EW-6 X.-. tL\ . ^^-529 V E-S
5^6
11-2
• -c-zA-i A-3
D-4' • A-5 C-4
A-7' C-1.
2^5 'C-S
A-8 , B-10
C-5 ^'
% .E-10
t* J-2
862 •
.J-3
J-4.
9-5
li-4
5-9
•E-8
M114-B1
.^E-4
E-S
H-6
.E-5 \
\
PROMO\TORV BC-4
BCi 'C-3'
.G-4 *-5
J-5
EW-3
BC-5
^.735
SHOTGUN SPRING t ,^^^£.".'^2
200 H-9
EW-1
>
.0-8
.G-7
G.6
L.
•x-4
396
TCC3 I
*^CC3A
417
X-5.
485
"509
FISH SPRING' \.
HORSE SPRING B \ HORSE SPRING A TO
H-10
_ - . ATK TACIL TV BOUNDARY
CONTOUB SHOWNC ARSfMC COMCFN-PATlON
H-10 • '.I'j'j CI' ^^; «ELL
KarthFax EnfiDeerinE, Inc. KarthFax EnfiDeerinE, Inc. KarthFax EnfiDeerinE, Inc.
EarViftix
MONITORING WELLS WITH
DETECTED ARSENIC IN ug/L
EarViftix
MONITORING WELLS WITH
DETECTED ARSENIC IN ug/L
EarViftix
MONITORING WELLS WITH
DETECTED ARSENIC IN ug/L
EarViftix
MONITORING WELLS WITH
DETECTED ARSENIC IN ug/L
EarViftix
MONITORING WELLS WITH
DETECTED ARSENIC IN ug/L
EarViftix
MONITORING WELLS WITH
DETECTED ARSENIC IN ug/L
EarViftix
MONITORING WELLS WITH
DETECTED ARSENIC IN ug/L
EarViftix
MONITORING WELLS WITH
DETECTED ARSENIC IN ug/L
ATK LAUNCH SYSTEMS INC. ATK LAUNCH SYSTEMS INC. ATK LAUNCH SYSTEMS INC.
1
44
REVISED DRAFT June 21, 2010
A.3 Groundwater Quality and Total Dissolved Solid Concentrations
Groundwater in the area west of the ATK facility is of very poor quality due to the high TDS or
"salt" levels. The Adams brothers initially drilled well EW-6 in 1955 for an irrigation source.
However, as noted in the well report "none of the waters were useable for irrigation purposes the
salt content being too high."
Groundwater well EW-6 was sampled May of 2001 and reported a TDS level of 7826 mg/L. With
assistance from Utah State University and the Western Fertilizer Handbook, this TDS value was
used to calculate the electrical conductivity (ECw), salt load applied to the land, and reduction in
yield of crested wheat grass as shown below.
ECw=7826/640=l2.23 mmhos/cm
7826 ppm TDS*2.72=21,287 lbs of salt added to land/acre foot of water
Based on Table 2-10 pg. 49, you would experience a 55% reduction in yield of crested wheat
grass.
As illustrated by Table 8.4 "Salt Tolerance of Crops" found in Design of Land Treatment Systems
for Industrial Wastes, this ECw is above the range of the very very salt tolerant crops. Given that
the pH for soil in this area is above 8.0 and the high ECw. it is not reasonable that this groundwater
could be used to support crops.
Table 8.4 Salt Tolerance of Crops (optimum pH)
I. Very Very Salt Tolerant
(EC 8-12 mmhos/cm)
U. Moderately Salt Tolerant
(EC 4-8 mmhos/cm)
III. Near-Neuaa!
pH Requirements
(EC 2-4 mmhos/cm)
Alfalfa (6.2-7.8) African Violet (6-7) Spinach (7-7.5) Apricot (6-7)
Aly8sum(6-7J) Alfalfa (6J-8) Spinach (6-7.4) Arborvitae (6-7.5)
Asparagus (6-8) Almond (6-7) Sorghum (5 J-7.5) Tobacco (5 J-7.5>
Batbeny (6-7.5) ' Barley (6.5-7.8) Sycamore (6-7 J) Tamarack (5-6J)
Bermuda Grass (7-8) Begonia (5.5-7.0) Sunflow (6.5-8) Bell Pepper (6-7)
Burnish Bush (5 J-7 J) Broccoli (6-5) Tomato (6.5-8) Black oak (6-7)
— . Cabbage (7-8) - — -Calendula (5.5-7.0) Vetches (7-8.2) Yam(fr-7)
Carnation (6-7.5) Celery (5.8-7.0) Wheat(6J-8) Cherry (5.5-7) ;
Canota(5.5-7J) Crab Apple (6-7.5) Zinnia (5 J-7.5) Douglas Fir (6-7)
CauUHower (5.5-7.5) Cotton (6 J-8) Hot Pepper (5 J-7)
Chrysanthemum (6.5-8) Cowpeas (7-8.2) Lantana (6-7)
Date Palm (7.5-8.2) Corn (6_5-8) Poinsettia (6-7)
Garden Beets (6-8) Cucumber (6.5-8) Quince (6-7)
Geranium (6-^) Johnson Grass (6.5-7.5) Rice (5-6 J)
Ivy (6-8) Lespedeza (7-8.2) Reed Canary Grass (5 J-7)
Panic Grass (7-8) Lily (6-7) Rose (5-<.5)
Peas (6-7.5) LiUc (6.0-7-5) Rye (5-7)
Peach (6-7.5) Maple (6-7.5) Soybean (5 J-7 J)
Purple Sage (7-8) Millet-Sorghum (7-8.2) Sesbania (5-7)
Rhodes Grass (7-8.2) Muskmellon (6.0-7.0) Potato (5-6J)
Salt Grass (7.5-8.2) Rhubarb (5.507.0) Sweet Potato (5-7)
Spinach (6-7.5) SafHower (6.5-7.8)
Sugar Beets (6.5-8.0) Snap dragon (6-7.5)
Sugar Cane (6-8) SnowbaU(6.5-7J)
WUd Mustard (7-8) Sweet William (6-7.5)
As illustrated by the USU fact sheet "Analysis of Water Quality for Livestock" Table 1 shows that
Groundwater Well EW-6 would be considered a poor water source for livestock, and exceed the
limit for some species.
45
October 11, 2010
ANALysiis OF VVATER QUALITY
FOR LIVESTOCK
eralualcd.for'th^K^ USU .'VrialvtlckT^
•l:abora'lohes'|8bl'^-75b^2217) or'at some rammerciai'labo-;:
zpaii),can>bc\sprepd .UiTou^h^
[.•Thes.eiari;,;ric)t;,u^^
samples could submi'lled to an aniuial .disease diagrios-;>
prepared io lest.. for'pcsUcldes ahd-orgE-nlc,toxins:. (Sce^i
•fogtsliea-.-jviierc-fd-Have Your Wat?r'Tested'taAJtali;-) ' '
* '• '? ••• ^' •-• A. Salinity • •' •, ' • \.
Sallnli.y refers, lo sails idis.solved in, waler.. The. anjpns
^' (negatively cliargcd ions') cominonly present include: car-
• bonaie. blcarbonate.,sulfate,.nllrale, chloride, phosphate'
; and fluoride. The calions (positively charged lonslinclude
' Calcium,-magnesium.-sodluin and potassium: •
•£ -Sallniiy may be measured as' Tot^ Dissolved Solids (TDS)
or Total Soluble Salts (TSS) and is expressed as pans per
• million (ppm) (which is equivalent to mg/l or ug/ml).
. Sallnlt^' may also be measured by electrical conducllvily
. (EC) and Is Ulcn expressed as reciprocal micro ohms per
• .ccnUmeler (umhos/cm) or decisiemehs per meter (dsym).
T7iere Is a close correlation prEe arid;pph-i H-ith the raluesf fv'
•orppnrjjcirig-abbutj.l-ys.ofth
500 unih'os/"cm and® 3;boO pp^^^^^ Ee'= 5;6o6 umjios/.cm');;-!- iS'
TK^efiecliseSi^i t^l^fu^sa^JtA^Heili^^iSl^pK^
m
_i.^w./..«j « »>"^uci.va...%vniiuui.ii£tiiii,..ii inej^are,iiien:Ci\'en:
wat«36fetow*sannl<y::i.Tb^ , . „
,\iith/spccics;-.agc.-,water,reqm iritATarjWyS'J
•ajid plfvsfologica) condiiion'.V '' f' " •:"-""i •;t- ,'-.fif -.-jf-' ;
As the' TDS. ofJwater'increases. ^liViakeValsOj'incrcases;' .^L -'^^
' excepit.ai. very • High'-contcriI swiiere*t he^.inim kis "rcfuse*To;' f • -.
drnik.,'-Depressed \vaier intake is accompanied^-bvydc- -fd'^l
pressed feed liiiakei-'..f''' -' '. }• '"'.>/ - K
Theiorisofmagriesium(Mg).calcium(CaTsodium(Na)aua ,
chlorldc,(Cl)allcon(jribuie to the salinity nrw-tiicr. aii'd tiiey .. .
may cause toxic effects because of this salinity effect.or by - j. '
inlerference with other elements.' Mui: ihes'e four ar'e'n'oV'1^
usually considered toxic.otiierwL<!K. -i,-.; ,'. . .'V'." ". J
Salinity, by itseir tells iidlhlng about'.vyhlc1i c!eme'n(s are . .V •",
present, but UUs may be of critical lin'portance. So^ when ~ ,
the salinity is elevated, the wa ler should be analvzed foi^'tlie ' T '!
specific anions and cations. I. .
The folloxv-lng tables give guidelines on potential uses of- \'!v ."f
waters of various-s'allnit}'; ' " '' "' ."' • '..
\ . ^ , - . . Table 1: TDS and SnpriPs V^ffpn\r.^in
Total Dissolved Solids (ppm). .
Species' . , „ Excellent , . Good •. .Fair. Poor LUnit
... Humans . -»
.' Horses-Wpi-klJig '
;;?H .,;-Gthcrs..';• • -i
Caitle ' : . , .
"•" Sheep •''' •-' • • • •'••'
J: ehlckcns ^'Poultry.,
1'.' Sivihc .' - •
0-800 • 600-1600 feOO-ZSOO . 2500-4000
0-lpOO, . , 1000-2600, 2000-3000, 3000-5000'
oqooo , •;-1000-2000'. 2000-4000 • 4600-6000'
9:1000, , , .,,1000-2000,. 2000-4000 ' 4000-6000"
0-1000' 1000-3000 3000-6000 6000-lOOOQ
p.-1000., 4• . -MOOO-BOOO V- '-• 2O00-f3O00 SOOO-So'oo"" „.
- (Young plgi-and markel pigs appear to toleraje less. thahsCatilc)
5000'
6000- '
10000
10066'
,15000 loob'' -'
Si. :.j.-f f./.i-;W;,-.1,,; M;
46
October 11, 2010
A.3 Comparison of Metals Concentrations in Wells Completed with Stainless Steel and
PVC
Table A-3
Groundwater Chromium and Molybdenum Concentrations (/^/L) in Stainless Steel and PVC Wells at
Well Number Stainless Steel Wells Well Number Polyvinyl Chloride Wells
Chromium Molybdenum Chromium Molybdenum
A-10 20600 636 G-1 5 0.5
A-2 163 0.5 G-2 73 0,5
A-3 323 19.5 G-3 5 0.5
A-6 5 0.5 G-4 5 0.5
A-7 5 0.5 G-5 5 0.5
A-8 24 11 G-6 105 0.5
A-9 7880 455 G-7 5 0.5
B-1 9520 356 G-8 12 0.5
B-10 5 0.5 HI 5 0.5
B-3 10700 467 H-10 5 0.5
B-4 8910 422 H-2 5 0.5
B-5 3730 122 H-3 5 0.5
B-6 7290 556 H-4 5 0.5
B-7 2170 250 H-5 850 0.5
B-8 10500 856 H-6 5 0.5
B-9 293 0.5 H-7 5 0.5
C-1 948 61.1 H-8 24 0.5
C-5 6440 266 H-9 5 0.5
C-6 5 53.6 J-1 5 4.1
C-7 7130 174 J-2 11 0.5
C-8 10500 701 J-3 5 0.5
D-1 5 0.5 J-4 5 0.5
D-3 5 38.8 J-5 5 0.5
D-4 39 2.3 J-6 5 0.5
D-5 458 8.8 J-7 5 0.5
E-1 8050 166 J-8 5 0.5
E-10 49000 2740 M508-1 109 0.5
E-2 32300 2390 M508-2 120 9.03
E-3 3490 184 M508-3 513 4.4
E-4 6650 258 M508-4 252 3.2
E-5 30100 2560 M508-B1 156 0.5
E-6 8270 949 M636-B1 5 0.5
E-8 5 0.5 P-1 5 26.3
E-9 2810 99.8 P-2 5 1.6 J
F-1 13300 1020 P-6 5 0.5
F-3 16100 814 P-7 92 0.5
F-4 521 0.5 P-8 42 7.58
LF-1 5130 291 P-9 22 0,5
LF-2 11300 1080 X-4 32 7.98
LF-3 8350 605 X-5 14 0.5
LF-4 4550 388
Average
Concentration 7502 464 64 2
47
October 11, 2010
A.4 Wells with Historically High Total Unfiltered Chromium Values
' / , , ; I,\. l!iih\e AA: Concentrations in p/Lr • v •
• Sampled 7/15/10
Well;. Filttered total Cr Unfiltered total Cr Cr VI Unfiltered Iron
A-10 < 10 21,300 <2 77,000
E-5 16 7,210 10 26,000
B-8 < 10 9,580 <2 44,800
E-2 < 10 62,200 <2 239,000
48