Response to ADEQ c. dated July 7, 1989 Page 3
..a ..
Alternative A-4 includes pumping and treating groundwater with concentrations above 100 ppb TCE. How was this 100 ppb target achieved? Target clean-up areas should be defined by concentrations above background and ARAR's. Response: Estimates predict that reducing the TCE concentration to 100 ppb in Subunit A will protect Subunit C from TCE contamination. Therefore, the scope of this alternative was not that of Subunit A remediation but that of Subunit C protection. See Chapter 5, Section 5.2.14, pages 5-8 to 5-9 of the FS.
Why does the heading for Alternative A-4 include a pumping rate? Including a pumping rate for this alternative but not the others is inconsistent. Pumping rates for the alternatives should be determined based on the desired time for restoring the aquifer, the number of wells to be pumped, and the target areas.
Response: Alternatives A-0 through A-3 use no action or air stripping (should MCLs be exceeded) treatment for withdrawal at point of use. Alternatives A-4 pumps ground water at a rate of 400 gpm from Subunit A using extraction wells, while the withdrawal rate of Alternatives A-0 through A-3 are dependent upon production well capacities.
The heading for Alternative A-4 mentions re-injection but the text beneath the heading does not include re-injection. In addition, why does Alternative A-4 specify a particular treatment method rather than 'just treatment in general. Either more alternatives should be included here and each alternative should specify methods of treatment for soil and groundwater, or the alternatives outlined here should be generic. Alternative A-4 suggests the use of production wells. Should the term "production well" be replaced with the term "extraction" wells or is the text referring to municipal and domestic supply wells?
Response:
o o
Reinjection is listed in the text beneath the heading (See Executive Summary, Page 3, Paragraph 2, Bullet 2 of the RI). As the text points out, the remedial alternatives that are listed in the Executive Summary are those that survived the screening process detailed in Chapters 4 to 6 in the FS. Since this is a summary of the alternatives most likely to be used it would be inappropriate to list all possible treatment methods. To retain consistency, air stripping should also be mentioned.
o
Comment noted. The text will be revised from "Removal would take place via production wells and treatment would be accomplished with air stripping." to "Removal would take place via extraction wells and treatment would be accomplished with air stripping."
4. EXECUTIVE SUMMARY. PAGE 3
This document should evaluate the potential alternatives rather than argue for a preferred or "recommended" alternative.
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 1 of 31
comments dated July 7, 1989 Page 4
m* ·
If the author insists on stating arguments for recommended alternatives, then please note that the No Action Alternative is not considered an acceptable alternative. No Action would not satisfy state ARAR's nor would it be protective of human health and the environment.
Response: The purpose of the RI/FS is to present the methodology used in the development of the remedial investigation and feasibility study as outlined by the Superfund program. As stipulated by EPA, the FS presents remedial alternatives which must undergo an evaluation methodology that satisfies certain criteria. The Executive Summary merely summarizes the results of the screening and evaluation process and presents a recommendation for consideration by EPA for approval, adjustment or reinjection. This applies also to the No Action alternative. The No Action alternative is suitable as a recommended alternative for consideration since the response action incorporates monitoring activities and implementation of institutional controls for groundwater withdrawal from Subunit C and the MFU for drinking water supply and maintaining the existing non-applicable use of Subunit A groundwater. Institutional controls, such as mandated screening depths within Subunit C and the MFU, would ensure continued protection of human health and the environment and thus, may be waived from ARARs.
5. CHAPTER 1. PAGE 1-2. PARAGRAPH 2 (LAND USE)
^ · *
jg · I
--
· fl I
mm ·
·
This paragraph is awkward. Are you referring to the use of land that is adjacent to the site? (Suggested wording: The land adjacent to the PGA site is used for residential, commercial, and agricultural purposes.)
Response: We find the meaning of this paragraph to be straightforward. The text is stating that land uses adjacent to the UPI site are for various purposes including residential, commercial and agricultural.
6. CHAPTER 1. PAGE 1-2, SECTION 1 2 3 PARAGRAPH 1 ...
M ]£
·
·
Inorganic contamination should be addressed in (Currently, the text only discusses VOC contamination.)
this
section.
0 K
Response: The subject of inorganic contamination is addressed in Chapter 1, page 1-3, Section 1.2.3, Paragraph 3 of the RI.
7. CHAPTER 2. GENERAL COMMENT
mm £
The units of concentrations listed in the text are inconsistent with the units used in the tables. This practice makes comparison between the text and the data very difficult. In addition, the use of different formats and order of presentation between the various tables makes comparison difficult.
Response: Concentration units have consistently been presented in terms of ug/kg for organic, metal, pesticide, and Total Petroleum Hydrocarbon chemical species. The two exceptions to this general statement occur in Chapter 2, Page 2-21, Section 2.3.3, Paragraph 3 of the RI and in
I
·
·
I I
Case 2:03-cv-02226-ROS Document 81-12 Filed 06/27/2006 Page 2 of 31
I I I I I I 1 t I I I I I I I I I I I
i-.cot'wuse to ADEQ comments dated July 7, 1989
Page 5
Chapter 2, Table 2.11 of the RI. This was done not to make the reading more difficult but was done in order to facilitate comparison of test
results to federal standards.
8. CHAPTER 2. PAGE 2-2. SECTION 2.2.2. PARAGRAPH 1
The second bullet of paragraph one is awkward. (Suggested wording: Evaluate past disposal points which represent potential sources for groundwater contamination.)
Response:
9.
Comment noted. j
CHAPTER 2. PAGE 2-3. PARAGRAPH 2
Figure 2.2 includes a description of the waste disposal areas. Including Figure 2.2 as a point of reference for the waste facilities and sampling locations would be helpful.
Response: Comment noted.
10. CHAPTER 2. PAGE 2-5. SECTION 2 2 2 3 PARAGRAPH 3 ....
Providing a list of the compounds that were identified during the
interviews would be useful. Response: The compounds are: calcium chromate, iron powder, titanium, magnesium, mercury, lead oxide, barium chromate, lead chromate and tungsten. This list is found in Chapter 2, Page 2-19, Section 2.3.3,
Paragraph 2 of the RI.
11. CHAPTER 2. PAGE 2-5. SECTION 2 2 2 3 PARAGRAPH 4 ....
Please provide a description of the "hot-gas" pesticide application method. When was it used?
Response: The hot gas dissemination process is discussed in the "Revised July 31, 1987 Soil Sampling Plan for Unidynamics Facility". A
device was used to disperse materials carried in hot gases. The process was tested between the time periods:
1968-1969 (pesticides).
1964-1970 (dyes) and
12. CHAPTER 2. PAGE 2-6. PARAGRAPH 2
Please explain why samples obtained from the reactive waste storage area were only analyzed for total petroleum hydrocarbons. Were other analytical methods used? What "reactive" wastes were stored in this area?
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 3 of 31
Response to AU*^ i_<^i_.__..^s dated July 7, 1989 Page 6
--
g |
Response:
"
* · ||
,fl ·
o The "Revised July 31, 1987 Soil Sampling Plan tor Unidynamics Facility" lists three analytical suites for Waste Facility 9 in Table 66 .. These are total petroleum hydrocarbons (EPA 418.1), total metals and EP-TOX metals.
o Various chromate , nitrate, perchlorate and assumed to compose the "reactive wastes".
oxide- compounds are
13. CHAPTER 2. PAGES 2-11 TO 2-18, SECTION 2.3.2
Although concentrations of VOC's in the soils vary among the potential disposal areas, the presence in the soils is so widespread that all the designated waste disposal facilities are probably potential sources of groundwater contamination. VOC concentrations detected at depth in the soils may be more an effect of the disposal method (into dry wells) than the result of off-gassing from the contaminated groundwater.
Response: The remedial investigation recognized the potential of various waste disposal areas contributing to the groundwater contamination. However, certain indicators, such as; depth of contamination versus depth of disposal facility; soil properties and mechanics and; available historical accounts, substantiate the assertion that most of these facilities, although potential contributors, are not significant contributors and that the widespread presence of VOC contamination is the result of off-gassing from the contaminated groundwater. For location specific discussions, see responses to comments 17, 18, 19, 20 and 21.
14. CHAPTER 2. PAGE 2-12
m · £ ^ I
B
1
Are the construction details of the dry wells known (I am especially interested in the depth and perforated intervals)? Are the "vaults" the same as the concrete sedimentaiton tanks? Please describe the design details of both (if they are different).
Response: The design details, such as depth and perforated intervals, are not currently known for the drywells, sedimentation tanks or vaults. The vaults are not the same as the sedimentation tanks but refer to the below grade collection facilities which contain stainless-steel 55-gallon drums, located adjacent to Buildings 1 and 6.
15. CHAPTER 2, PAGE 2-12, SECTIOH 2 3 2 1 ...
TM at
^ · ·
What were the sampling intervals for Haste Facility 4 and which samples were analyzed? (See the comment below in regard to Table 2 4 .)
£
Response: The analyzed samples were taken from depths of 10, 20, 30, , 40, 50, 60 and 70 feet below land surface. This information is presented in Chapter 2, Table 2.3 of the RI.
· *
I 1
Case 2:03-cv-02226-ROS Document 81-12 Filed 06/27/2006 Page 4 of 31
Response ti....:-. ..^ ;.
-
I I I I I I 1 1 I I I I I I I I I I I
Page 7
16. CHAPTER 2. TABLE 2.3 AND 2.4
Using the same format for the two tables listed above (especially in regard to sampling intervals and analysis of samples) and presenting the same types of data in the two tables would make comparing the tables and tracking the samples easier for the reader.
Response: Comment noted.
17. CHAPTER 2. PAGE 2-13, SECTION 2.3.2.1.
PARAGRAPH 2, LAST SENTENCE Would a clear maximum in heterogeneous soil profile?
TCE
concentration
be
expected
in
a
PARAGRAPH 3, LAST SENTENCE Can the conclusion be made that the "low" concentration of TCE found in the subsurface is directly related to the amount of TCE disposed in a dry well? Other factors are at work and could affect the TCE concentrations (i.e. time and the potential for both lateral and
vertical migration away from the dry well.)
Speculation that TCE is "off-gassing" from the water table is unsubstantiated. First, if TCE is partitioning to soil-gas and migrating upward, then TCE concentrations in soil samples should reflect the process. Second, if in partitioning is occurring, then one would expect to find the highest concentrations of TCE at the water table and gradually decreasing all the way up towards the surface (dissipating upwards). Soil boring results seem to suggest varied concentrations at different depths (no definite depth/concentration correlation) and possibly indicate preferred zones of migration (as night be expected from disposal in a dry well and downward migration of fluid). Third, if off-gassing is occurring one night expect to find similar patterns of contaminant concentration in all the borings. Finally, even if TCE is partitioning and migrating fron the water table, it still constitutes a zone of soil contamination that requires evaluation and consideration. Also, dry wells usually discharge through a perforated pipe located below a ten to fifteen foot deep settling chamber (and the upper portion of the casing is not always perforated). Consequently, contamination resulting form dry wells would tend to occur below the upper fifteen or twenty feet of soil.
LAST PARAGRAPH
Switching units from micrograns per liter to micrograns per cubic centimeter causes unnecessary confusion.
Response: Chapter 2, Page 2-13, Section 2.3.2.1, Paragraph 2, Last Sentence
The sentence hypothesizes the existence of three phases in the soil media: soil vapor, sorbed TCE coating soil particles and aqueous phase with dissolved TCE. Even within a heterogeneous soil profile the amount
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 5 of 31
Response to ADEQ comments dated July 7, 1989 Page 8
of contaminant per volume of soil ascribed to the solvent phase or aqueous phase could vary.
For example, consider the case of an aqueous phase contaminated with TCE moving downward through the soil. This phase moves through the soil due to capillary action and/or gravity. This phase does not simply drain through the soil because the liquid can be held by the soil pores through surface tension. When a column of water is not heavy enough to overcome the surface tension of the soil pore it cannot move downward any further. This would be a "front" at some percentage of soil saturation called the irreducible saturation. The soil near the retained liquid would have some of the liquid sorbed onto the soil surfaces. The amount of contaminant sorbed onto the soil would be significantly less than the contamination at the "front." The contamination at the front would represent a. clear maximum concentration if a profile were composed. Paragraph 3, Last Sentence o o Comment Actually references pp. 2-13 to 2-14 The concentration must be related to the amount of TCE disposed in a dry well because of the principle of conservation of mass. There are mechanisms that cause the migration of contaminants in the subsurface. Many of these are in turn driven by amount (surface tension, dissolving in soil water) and concentration (diffusion). The extent to which these mechanisms play a role in migration is dependent on amount and concentration. Greater amounts and higher concentrations indicate greater migration potential. Therefore, it appears that low measured concentrations are related to lesser disposed amounts.
Regarding the attribution of TCE observations to off-gassing: - Generally TCE concentrations do reflect the process of volatilization from the ground-water surface. The highest TCE concentrations were observed at depth for borings in near Waste Facilities 3, 5, 8, 7, 10, and Buildings 11 and 19, and the Drum Storage Area. In these borings TCE was observed at higher concentrations nearer the water table or were only detected near the water table. - The text presents that variations in TCE concentrations in Boring 04A could be attributable to variations in soil properties such as porosity, density, and permeability (Page 2-13, para 2). The near uniform nature of contamination in Boring 04A could be attributable to the soil vapor achieving equilibrium with the
K JP
M| ·
· · ·!
>· W ·
M £
^
o
· ·
jft jf
w *
fi
flt
contaminated ground water throughout the soil column. This process would take an undetermined amount of time. This process would be comparable to placing a bottle of cologne in one corner of a closed room. Even with no air currents, the concentration of cologne would eventually be the same throughout the room.
· _ ·
I I
Case 2:03-cv-02226-ROS Document 81-12 Filed 06/27/2006 Page 6 of 31
I I I
Response to ADEQ comments dated July 7, 1989 Page 9
-
The PGA soils sub-committee has not yet determined appropriate soil clean-up standards. Evaluation and consideration of soil contamination emanating from the ground water is not currently justified by State action levels. The concentrations are below state action levels.
o
The typical dry well design at Unidynamics' facility located the discharge approximately 30 feet below ground surface.
I I I 1 I I I I I I I I I I I I
o
Comment noted regarding change of units in last paragraph of section.
18. CHAPTER 2. PAGES 2-15. SECTION 2.3.2.2
PARAGRAPH 1
Table 2.1 indicates that Waste Facilities 3, 5, and 8 were associated with dry wells. Higher concentrations at depths of 60 feet probably result from the injection through the dry wells rather than off-gassing.
Response: Chapter 2, Figure 2.2 of the RI approximates the depth of the dry wells for Waste Facilities 3, 5 and 8 as 30 feet. The VOC concentrations as a function of boring depth is listed in Chapter 2, Table 2.8 of the RI. If the theory that the organic concentrations are a result of injection through the dry wells is accurate, then it would be expected that some organics would be detected in the 30-50 feet boring depth range. Since Table 2.8 clearly points out that detection of organic compounds occurs only at depths greater than 50 feet, the assumption that higher concentrations are a result of injection through the dry wells is probably inaccurate.
PARAGRAPH 2, LAST SENTENCE
The waste facilities discussed consist of sedimentation tanks connected to dry wells. The occurrence of TCE at depth is probably the result of this disposal. If no surface spills occurred, then why would shallow contamination be expected?
Response: If TCE detection in the soil borings was a result of contaminant disposal through dry wells rather than off-gassing from contaminated ground water then TCE should have been discovered in shallower depths for the same reasons as those listed above. Since this does not seem to be the case, this assumption should be dismissed.
19. CHAPTER 2. PAGE 2-16. SECTION 2.3.2.3.
Low levels "indicate11 that this facility is not a source of groundwater contamination? The low levels may "suggest" that the facility is not a source but they do not indicate so. The text does not substantiate the conclusion.
Response: Soil borings from Waste Facility 7 were submitted for VOC analysis for depths of 10, 20, 30, 40, 50, and 60 feet below land surface (see Chapter 2, Table 2.4 of the RI). The results are presented in Chapter 2, Table 2.8 of the RI and indicated that only 1,1,1-TCA is present and only at a depth of 10.0-11.5 feet below land surface. No
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 7 of 31
Response to ADEQ comments dated July 7, 1989 Page 10
s
~
other organic compound is found at any other analyzed depth. If this facility were to be a ground water contaminant source, than a 1,1,1-TCA concentration gradient would be present throughout the soil boring. Since this is not the case, the conclusion is correct that the data in the text indicates that Waste Facility 7 is not a source of ground water contamination.
20. CHAPTER 2. PAGE 2-16 AND 2-17. SECTION 2 3 2 4 ...
If TCE or TCA were detected in every interval from 10 to 50 feet, than this facility represents a potential source of groundwater contamination.
Response: The text reads: "This facility is probably not a significant source of VOCs in ground water". This statement does not eliminate this facility from being considered as a potential source of ground water contamination. It asserts that this facility is not a significant source of ground water contamination.
21. CHAPTER 2, PAGE 2-17, SECTION 2 3 2 6 PARAGRAPH 2 .... SENTENCE 2
Define "low" as used in this sentence. Use of an actual concentration range would add clarity to the text. Presumably, concentrations were above detection levels, but were they below 500 ppb?
Response: Laboratory results for soil borings 19A-C are listed in Chapter 2, Table 2.8 of the RI. TCE concentrations range from 147-1480 ppb at soil depths of 20-40 feet below land surface. The highest detected concentration of TCE is relatively low when compared to the concentrations detected in Waste Facilities 1 and 4.
fl| m
m ·
^ ·
Higher concentrations of TCE at depth may also be a manifestation of disposal through a dry well.
Response: As stated in the text, Building 19 is located near Waste Facility 1. Waste Facility 1 is comprised of 4 dry wells (see Chapter 2, Figure 2.2 of the R ) The disposal of solvents into these dry wells I. has resulted in ground water contamination at TCE levels exceeding 100,000 ug/kg which in turn has led to the discovery of TCE in Boring 19A-C due to off-gassing of contaminants from the groundwater. Therefore, to state that higher concentrations of TCE at depth may also be a manifestation of disposal through a dry well is unnecessary and redundant since this has already been shown to be true.
22. CHAPTER 2. PAGE 2-18. SECTION 2 3 2 7 ...
tt
j* · B
ft. V
·»
Attempting to guess the concentration of the source seems pointless since the volumes of material disposed are not even known. In addition, the suggestion that rainwater filtering through empty drums constituted th« original source is unsubstantiated and represents otir* «neciilatton. the and pure speculation.
. ·
·§
I 1
Case 2:03-cv-02226-ROS Document 81-12 Filed 06/27/2006 Page 8 of 31
I 1 1 I i I I I I I I i I I I I I 1 I
Response to ADEQ comments dated July 7, 1989 Page 11
Response: Concentration scientifically determined laboratory. Second, it is disposed material in order
values were not "guessed" at, they were using EPA Method 8010/8020 at an approved not necessary to know the original volume of to determine concentration within the soil.
23. CHAPTER 2. PAGE 2-18. SECTION 2.3.2.8 If contamination is present, then its a potential source. range of concentration detected? Response: o The text does not dismiss the solvent collection area as a potential contamination area. It states that these areas are not significant ground water contamination sources. Chapter 2, Table 2.8 of the RI lists concentration ranges for the following chemicals (note: no distinction is made between boring or boring depth): Compound
TCE 1,1,1-TCA Ethyl Benzene Xylene
What was the
o
Concentration Range (PPB)
89-4260 12-10800 563 743-4600
24. CHAPTER 2. PAGE 2-19 to 2-21. SECTION 2.3.3
The presence of high concentrations of metals in selected soil samples may not be anomalous or be disregarded. Instead, they may be indicative of a problem in a fairly limited area.
Response: The text does not disregard results from soil samples as being anomalous. The discussion concerning barium and aluminum concentration results (Chapter 2, Page 2-20, Section 2.3.3, Paragraphs 2 and 3) states clearly that the samples from a tank (for barium) and
from within a pond (for aluminum) were not representative of soil concentrations. Only these were considered anomalous and disregarded. It was never implied that a problem could not exist within a limited area.
25. CHAPTER 2. PAGE 2-20. PARAGRAPH 3
It's a little too convenient to say, "...the consistent occurrence of
arsenic in soils at OPI facility above background determined for the
airport at the southern part of the study area probably indicates that background concentrations at Unidynamics facility may be generally higher than for the airport." Unidynamics is locate less than one mile from the airport. It seems unlikely that two sites located less than one mile apart possess different ambient soil values for arsenic. This sentence is misleading.
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 9 of 31
&esp.. -*j ADEQ comments dated July 7, 1989 Page 12
m
£ W M
· ^
Response: There are several circumstance which support the text's contention that arsenic background concentrations may differ for soils at the UPI and PGA sites.
1) A review of manufacturing processes and interview results indicated that arsenic was never used at this site. For this reason, arsenic should not have been detected unless it was a component of the ambient soil.
2) Soil sampling was performed at Waste Facilities 2, 3, 5, 6, 8, 9, 10, and 11. The results are listed in Chapter 2, Table 2.9 of the RI. The mean concentration of arsenic was calculated to be 21.6 ppm with a standard deviation of 7.6 ppm. There did not seem to be any relationship between soil depth and arsenic concentration. This analysis showed that the arsenic concentration within and throughout the soil remained fairly constant giving credence to the theory that ambient soil conditions (at least for arsenic) for UPI and PGA may indeed be different.
3) The assumption that arsenic concentration soil levels at UPI are the result of arsenic disposal is not supportable. If this assumption were to be true then it would be expected that an unusually high level of arsenic would be found at one or two locations (as was the practice of TCE disposal). Instead, the evidence points to a low, constant level of arsenic throughout the site. This would lead away from the idea of the higher UPI background results being a consequence of UPI disposal and toward the idea that there is a naturally occurring level of arsenic that is higher at the UPI site.
26. CHAPTER 2. PAGE 2-21, PARAGRAPH 2
' · m tt |p
« ^
ft '·
1
£
'
Were samples obtained just from within the tank or were they obtained from around and below the tank? It is not clear in the text. With such high values, was the possibility of tank leakage addressed in the sampling?
Response: As stated in the text, Stage II samples exhibiting the highest concentration of the various metals were selected for EP toxicity analysis of priority pollutant metals. These samples are listed in Chapter 2, Table 2.11 of the RI. The location feature that is sampled is identified from the sample designation using Chapter 2, Table 2.2 of the RI. Sample Designation Sample B Sample C
8A
· TM
tm
^ · *
·
Feature Sampled Building 11 - Borings Building at Front of £
·
Waste Facility 8 - Boring at Dry Well
10A 7A 7B
Waste Facility 10 - Boring at tank Waste Facility 7- 2 Borings in Leach Field
m
I I
Case 2:03-cv-02226-ROS Document 81-12 Filed 06/27/2006 Page 10 of 31
I I I 1 I I I I i I t I I I I I I I I
Response to ADEQ comments dated July 7, 1989
Page 13
The Phase III Sampling Plan is summarized in Chapter 2, Table 2.4 of the RI. This table reveals that samples were analyzed for boring depths that were below the level surface. (Stage I Samples, as described in Chapter 2, Page 2-4, Section 2.2.2.2. of the RI, are those from inside the tank).
From all of this information, the question should be addressing Sample IDA only. Again, referring to Chapter 2, Table 2.11 of the RI the EP Toxicity Test Results for this sample for each metal of interest are listed below (unit are ug/1):
Arsenic < 0.5 Lead < 0.1
Barium Cadmium
< 1 < 0.1
Mercury < 0.01 Selenium < 0.5
Silver < 0.1
Chromium < 0.1
Interpretation of this data reveals that the highest detected metal, barium, has a concentration that is less than one percent of the Federal EP Toxicity standard of 100 mg/1. Groundwater quality date coupled with the EP Toxicity data indicates that the soil at this particular location has a low metal concentration and does not serve as a source of metals to ground water. Therefore, the possibility of tank leakage need not be
addressed in this sampling.
27. CHAPTER 2. PAGE 2-21. PARAGRAPH 3
What about the concentration of metals in relation to ADHS health-based soil clean-up levels? Although not promulgate, the clean-up levels still constitute a "to be considered" (TBC). Response: In our previous comments we demonstrated why assumptions behind the ADHS numbers are not similar to circumstances at the site; hence, as TBCs, the are not useful.
o The ADHS - suggested health-based clean up levels for metal contaminants are listed in Chapter 2, Page 2-37, Table 2, Vol. I (Public Comments Draft) of the RI/FS. Seven metals within the UPI site have been found to have soil concentrations that exceed average background levels analyzed in soil samples at the PGA site: arsenic, barium, aluminum, mercury, lead, chromium and zinc (see Chapter 2, Page 2 1 - 9 of the R ) I . There do not appear to be any ARARs that are directly related to metal contaminants in soils at the UPI site. And, as was pointed out, ADHS health based soil clean up levels may be (but are not now) adopted at some time in the future in the State of Arizona.
o
28. CHAPTER 2. PAGE 2-21. SECTION 2 3 4 ..
Background concentrations of dieldrin and chlordane would need to be determined before these concentrations are attributed to agricultural use only.
Response: Comment noted.
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 11 of 31
Response to ADEQ commetvLc. dated July 7, 1989 Page 14 29. CHAPTER E. PAGE 2.22. SECTION 2.4
.
:
=
1st billet- This is only true for 4,4'-DDE.
Response: Comment noted.
4th billet- Table 2.1 lists a number of locations where disposal of solvents occurred into dry wells. Therefore, unless these solvents did not include TCE, distinct evidence does exist that TCE disposal to soils occurred at these other locations.
Response: Since no records were kept of the solvent waste disposal system at UPI, it is impossible to speak with absolute "confidence as to which location a particular solvent was discarded. Therefore, inferences must be made based upon soil boring analysis. The Waste Facilities which could have conceivably received waste TCE are numbers 1, 2, 3, 4, 5, 6, 7, 8, 10 and 12, Buildings 11 and 19, Drum Storage Areas A and B, and Solvent Collection Areas A, B, C and D. No TCE was detected in Waste Facilities 2, 7 or 8, nor in Building 11 (Chapter 2, Table 2.8 of the RI) so these can be eliminated. Waste Facilities 3, 5, and 6 contain TCE concentrations only at depths below 60 feet and in quantities that are most likely the result of off-gassing from contaminated ground water and not migration from a dry well (Chapter 2, Pages 2-15 to 2-16, Section 2.3.2.2 of the RI). The TCE concentrations found at the remaining sites, Waste Facilities 4, 10 and 12, and the Drum Storage and Solvent Collection Areas, may or may not be a result of disposal to the soil. However, the concentrations are low (compared to Waste Facility 1) so that no definitive judgment can be made. Therefore, unless distinct evidence ( . . written records, verbal ie confirmation, etc.) can be found, then the statement in the RI stands. · ·
fl|
w fl *
|
· TM «| (
_-
·
last billet- The presence of 1,1,1-TCA in groundwater beneath the facility indicates that its presence in the soil was significant enough to impact groundwater.
Response: The text reads: "concentrations of TCA in soil are not a significant source to groundwater". TCA concentrations in the soil (or in Subunit A groundwater) are insignificant when compared to TCE concentrations. Since the methods used in treating TCE are also successful in treating TCA, the relatively small concentrations of TCA will not need to be considered in the design of the treatment process. This is the justification for the comment in the RI.
30. CHAPTER 3. PAGE 3-1. SECTION 3.1.1, PARAGRAPH 1
· ·
I
« B
·
Please provide well completion data for monitoring wells 1-4. Response: The available well completion data for monitoring wells 1-4 is found in Chapter 3, Page 3-19, Table 3-10, Vol. I (Public Comments Draft) of the RI/FS.
jfj ^ B
m
I I I
Case 2:03-cv-02226-ROS Document 81-12 Filed 06/27/2006 Page 12 of 31
I I I I I I I I I I I I I I I 1 I I I
Response to ADEQ c dated July 7, 1989 Page 15 31. CHAPTER 3. PAGE 3-3. (LAST BILLET)
The Phase II report stated that a Cement Bond Log was run on MW-14, but the log is not included here. Was the log run but just excluded? Or is the statement incorrect?
Response: The log was run but was excluded.
32. CHAPTER 3. PAGE 3-3. LAST PARAGRAPH
If well 33dcd is an integral part of the monitoring network, then why isn't water quality data for this well included in Appendix D? Although it is stated that 22 wells were sampled during the remedial investigations, no data is included for any wells other than the UP I monitor wells.
Response: Well 33dcd was sampled and monitored by EPA. Likewise, the other wells (not included by UPI) are included under EPA's reports.
33. CHAPTER 3. PAGE 3-8. LAST PARAGRAPH
This site is underlain by several thousand feet of alluvial sediments.
Response:
Comment noted.
34. CHAPTER 3. PAGE 3-10. LAST PARAGRAPH
Subunit B does not hydraulically separate Subunits A and C.
Response: Subunit B is comprised mainly of finer-grained material. Because of this finer-grained material, Subunit B has a lower permeability and hydraulic conductivity than that of either Subunit A or Subunit C. Vertical and horizontal velocity gradients from Subunit A to Subunit C are impeded because of Subunit B. This condition defines a hydraulic gradient.
35. CHAPTER 3. PAGE 3-15. LAST PARAGRAPH
TDS concentrations in on-site Subunit A monitor wells are significantly higher than in off-site wells. Water quality types are different on-site and off-site. Therefore, it is likely that the facility activities have had significant impacts on inorganic water quality in addition to the historic agricultural activity in this area.
Response: The observed variations in TDS concentrations and water quality types may have origins other than facility activities. The wells are widely spaced and the observed variation may be a result of natural variability. Off-site wells are generally deeper than on-site wells and the variability may be related to this difference in depth. MW-1, an upgradient well on site contains the same general TDS and water quality type as monitor wells on the facility. This indicates that "facility activities" are not responsible for the variability observed.
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 13 of 31
co &DEQ comments dated July 7, 1989 Page 16
_ » M m
g
In addition, interviews and a review of operations dicf not reveal any processes that would have a "significant impact on IDS or water quality types.
36. CHAPTER 3. PAGE 3-18. PARAGRAPH 3
No data is presented to support changing TCE concentrations with time. A series of figures with actual TCE concentrations over time would be more useful than the mean concentration values presented in Figure 3.13, Response: Comment noted.
= ·
37. CHAPTER 3. PAGE 3-18, PARAGRAPH 3 (Subunit A)
I
Is there a possible explanation for the rise in the TCE concentration for monitoring well MW-12?
Response: Yes, MW-12 is in the plume, downgradient of the source, screened only in Subunit A. 38. CHAPTER 3. PAGE 3-19
PARAGRAPH 1
£ ||
--
fl
I 1
What is the source of TCE concentrations in well SC4A if not necessarily attributable to TCE in Subunit A? Does this mean that Subunit C is contaminated at this location?
PARAGRAPH 2
By not providing waste quality analysis over tine, it As difficult to substantiate the statement that TCE concentrations in MW-6 do not indicate a rising trend in concentrations. A TCE concentration of 6 micrograms per liter at MW-6 exceeds MCL's for TCE. Response:
o Subunit C is not likely to be contaminated at this location, this is a typo and Subunit A in the last sentence should be Subunit C.
i
ft ·
·
I
· £
o
o
The text states that the agricultural production well screened in both subunits A and C.
SF4A is
Within the well SF4A, water from subunits A and C would be mixed. Subunit A water would be diluted with subunit C water.
Paragraph 2 o Measured values fluctuating between 2.0 and 6.0 mg/1 are interpreted to represent the inherent variability in sampling, handling and analyses accuracy since no apparent trend is discernable. · TM
1 I I
Case 2:03-cv-02226-ROS Document 81-12 Filed 06/27/2006 Page 14 of 31
Response to ADEQ comments
I 1 I I I I I I I I I 1 I I I I I
dated July 7, 1989 Page 17 42. CHAPTER 3. PAGE 3-19, LAST PARAGRAPH
The rationale here seems to be that since the well only serves a warehouse, its not important. First, it supplies a warehouse which employs approximately 280 employees. Second, the water pumped from COG #10 provides the business with water that is utilized in food processing. Third, the exclusivity of the aquifer is inconsequential to
the regulatory need for protection. (Also, the density of TCE aquifer.)
Response:
All aquifers in the state (unless
otherwise reclassified) are protected by statute for drinking water use.
could affect its movement into the B/C
o o
The heading Paragraph 1.
of
the
comment
should
be
Chapter
3,
Page
3-20,
No judgment of the well and importance is implied or intended. The well is not used in food processing. Food warehousing nearby does
not require the use of water for storage.
o The Arizona law (referred to) is not considered an ARAR, see our legal comments dated August 1, 1989.
43. CHAPTER 3. PAGE 3-20. SECTION 3 2 4 ..
Although drinking water is available from the aquifers deeper than those already affected by VOCs, it is not reasonable to require the drilling of deeper wells to acquire this water. Additionally, no data is available to determine if the MFD and/or LCD beneath the UPI site have been affected by VOC contamination.
The implication in this section is that drinking water supply wells are not located in an area that could be impacted by the VOC contamination
from Unidynamics. However, there are City of Goodyear wells located within 500 feet of UPI's property boundary. These wells consistently detect TCE contamination.
Response: While it is true that no VOC contamination data is available for the MFU and/or the LCU underlying the Unidynamics site, this does not preclude investigation of (its) possible use. This is especially true when the fact that TCE is not detected in the MFU at
other locations.
There is one well (COG #2) located within 500 feet of the Unidynamics site. Groundwater data from this well is found in Chapter 3, Table 3-4 of the RI/FS (Public Comments Draft). According to this table, the average TCE concentration for this well and City of Goodyear wells 1, 3, and 6 is less than 1.5 ppb, well below the 5 ppb MCL. The location of COG #2 is not within the known boundary conditions of the Unidynamics' groundwater gradient. It can reasonably be concluded that Unidynamics
has not contaminated this particular well.
Therefore, to assert that
i
Case 2:03-cv-02226-ROS Document 81-12 Filed 06/27/2006 Page 15 of 31
Response LU »_~ .,, dated July 7, 1989 Page 18
_..__
-
VOC contamination from Unidynamics has an impact on drinking water just because a well is located within 500 feet of the facility boundary is not borne out by the detection results.
44. CHAPTER 3, PAGE 3-21. FIRST PARAGRAPH
The presence of VOC contamination in Subunit C indicates that Subunit B does not act as a hydraulic barrier between Subunits A and C.
Response: Comment noted. In the text, "hydraulic barrier" was replaced with "to inhibit movement of groundwater". This revision appears in the 5/4/89 version; the most recent document.
45. CHAPTER 3, PAGE 3-22. SECTION 3.3.2, FIRST SENTENCE
This sentence implies that the Subunit A aquifer is not considered a drinking water source. Either change the sentence or qualify the paragraph by stating that state law designates all aquifers for drinking water use.
Response: See response to Comment 2.
=
P m B
^
TM
46. CHAPTER 3. PAGE 3-22. FIRST PARAGRAPH
The higher TDS concentrations in Subunit A on-site as compared to off-site indicate influences in addition to the historic percolation of irrigation return flow.
Response: Comment noted. See response to Comment 35.
B deep
·
47. CHAPTER 3. PAGE 3-22. SECTION 3 3 2 .. SDBUNIT C *
First, meaning of the work "poor" is unclear as used in this sentence. · Either define the word or restate the sentence. Second, whether the aquifer is suitable for drinking water is irrelevant to the need for remediation. m* Response: Comment noted. The .text goes on to state that TDS exceed the recommended secondary drinking water standards and that nitrates approach the drinking water limit. Therefore, it is appropriate to state that the quality of Subunit C, although suitable for drinking water supply, is still poor.
LAST PARAGRAPH
^ · *
1
Concentration «ay suggest that Subunit B impedes downward movement of contaminants, but they do not necessarily indicate so. (Otherwise Subunit C would not be contaminated)
·» I
I I i
Case 2:03-cv-02226-ROS Document 81-12 Filed 06/27/2006 Page 16 of 31
I I I I
dated July 7, 1989 Page 19
Response: Although Subunit B may be an impediment to contaminant migration, it is still possible for contaminants that were originally in Subunit A to be found in Subunit C. An impediment is a hindrance to migration, not a complete barrier. See response to Comment 2 also. Wells which are screened in both Subunits A and C provide a gravity conduit by which Subunit C can be contaminated from Subunit A.
48. CHAPTER 3. TABLE 3.1
This table is illegible.
Response: Comment noted.
49. CHAPTER 4. PAGE 4-1. PARAGRAPH 3
TCE is still present in soils not associated with Waste Facility 1. These other soils are probably continuing sources also.
I I
Response:
o o The text does not deny the presence of TCE in soils not associated with Waste Facility 1. The text does not deny that some of the other soils areas may be continuing sources also (in fact, this may or may not be the case). However, to claim that all other soils are probably continuing sources is too extreme. Technical analysis using the results of soil borings for Waste Facility 3, 5 and 6 (Chapter 2, Pages 2-16 to 2-17, Section 2.3.2.2 of the RI) asserts that soil contamination is the result of off-gassing from ground water contamination (see response to Comment 1 ) In addition, Building 11 (Chapter 2, Page 2-17, 8 . Section 2.3.2.5 of the RI) and Building 19 (Chapter 2, Pages 2-17 to 2-18, Section 2.3.2.6 of the RI) do not appear to be contributing to ground water contamination based on collected data.
I I 1 I I I I 1 I I I
50. CHAPTER 4, PAGE 4-1. LAST PARAGRAPH
Strike the first sentence and replace the word "impedes" with "hinders" or "slows" in the next to last sentence.
Response: Chapter 2, Table 2.1 of the FS is a summary of the organic compounds detected in Subunit C. From this table, the range of TCE concentrations found in Subunit C is 0.7-5.5 PPB. This substantiates the statement that TCE is generally confined to Subunit A, and that the term "impedes" is synonymous with the term "hinders" or "slows". Therefore, it is unnecessary to revise the text.
51. CHAPTER 4. PAGE 4-2. FIRST PARAGRAPH
The Environmental Quality Act protects all aquifers as drinking water sources.
Response: See Response to Comment 2.
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 17 of 31
1 t
TELEPHONE - (602) 832-4100
TELEX -- 667*96
---------------------------------------------- TWX -- 910-059-0883 FAX - 602/932-8949
CRANE
UNIDYNAMICS/PHOENIX
UNIDYNAMICS/PHOENIX
· POST OFFICE BOX 46100 ·
f-'l<~£-
.....1 {?r\ ,,£-'· ,,- 7J
1
i i i i i i· t i i i i I i i t i
PHOENIX, ARIZONA 85063-6100
2 August 1989
Mr. Jeff Rosenbloom, Chief Enforcement Programs Section United States Environmental Protection Agency Region IX 215 Fremont Street San Francisco, California 94105 RE: Response to CH2M Hill comments - Unidynamics RI/FS Report
Dear J e f f :
Enclosed per your request are Unidynamics' responses to CH2M Hill's comments on our RI/FS.
If you have any questions, please contact me at 602/932-8245.
Very truly yours,
£.0CX^£~-_
W . C . Donahue Director Human Resources
WCD/dl Enclosures
xc:
M. F. G. T.
Corash Stephenson Seifert Ungerland
1000 NORTH LITCHFIELD ROAD
·
GOODYEAR, ARIZONA 85338-1295
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 18 of 31
I t
Responses to CH2M Hill comments dated 7/6/89 p age 1
RESPONSE TO CH2M HILL COMMENTS
R E C i_ I Y L_ I
AUG
HUMAN
2 196?
i i i i i i i i i i i i i i i i
1.
Groundwater Alternative GW-A.l; The maximum predicted drawdown under this remedial action alternative is 88 feet. The thickness of Subunit A used in the simulation was 90 feet. In an unconfined aquifer, the maximum "safe" drawdown for an extraction well field is 50 percent of
the aquifer saturated thickness. This is to account for possible aquifer heterogeneity or subsequent water level fluctuations. Clearly, the withdrawal of 1,000 gpm from this aquifer would cause extensive dewatering. If the pumped water were reinjected after treatment, the drawdown would be reduced, but that process is not taken into account in
this alternative. An analysis of the capture zone estimate was not made since this alternative cannot be successfully implemented.
Response: We agree that substantial drawdown of the water table would occur under this pumping scenario and that it may exceed the practical limits of the Subunit A aquifer. This extremely aggressive pumping scenario was included in our analysis in order to provide a range of options for EPA to evaluate as requested. We are pleased that EPA's technical consultant recognizes the limitations of such an aggressive pumping scenario and agree with their conclusion that further consideration of this pumping scenario is not warranted.
2.
Groundwater Alternative GW-A.2: The maximum predicted drawdown under this alternative is 126 feet. As stated above, Subunit A has a saturated thickness of only about 90 feet. Therefore, this alternative will also cause extensive dewatering of Subunit A. No evaluation of the capture zone estimate was attempted for the reasons stated above. Response: See response to comment #1. The maximum predicted drawdown under
3.
Groundwater Alternative GW-A.3:
this alternative is about 1.5 feet. Using the well location recommended by Dames & Moore, this pumping scheme will capture only about 15 to 20
percent of the target area we estimate to be contaminated above ARAR levels. If a more suitable well location were chosen, approximately 850 feet to the north of the recommended location, 50 to 60 percent of the target area contaminated above ARAR levels could be captured. Response: The "target area" estimated to be contaminated above specified levels by EPA's contractor is subject to a wide variation in extent since TCE above 5.0 ppb has only been detected very infrequently in Subunit C in a well cluster at a single location. One well in the cluster is only partially completed in Subunit C. An almost infinite number of "target areas", as assigned by the EPA contractor in this comment, can be drawn around a single point. However, all such "target areas" may be meaningless since it has not been conclusively shown that Subunit C exceeds ARARs in the vicinity of the plant site where EPA requested that cleanup alternatives be evaluated. Dames & Moore selected a different "target area" than the EPA contractor upon which to base its evaluation. This analysis was performed solely at the request of EPA. Given the lack of conclusive data, and the
i
Case 2:03-cv-02226-ROS Document 81-12 Filed 06/27/2006 Page 19 of 31
Responses to CH2M Hill comments dated 7/6/89 Page 2
problems posed by increased drawdown in the area of high Subunit A contamination (as discussed in Unidynamics'. letter of July 17, 1989) the proposed cleanup is appropriate. 4. Groundwater Alternative GW-A.4; The maximum predicted drawdown under this alternative is about 2 feet. Using the well location recommended by Dames & Moore, this pumping scenario will capture only a few percent of the target area we define as being contaminated above background levels. Even with an optimal well location, this alternative will only capture 5 to 8 percent of the target area above background levels. Additional wells pumping at higher rates will be necessary to capture the areal extent of groundwater contaminated above background levels.
Response: Please see our response to comment #3 above for a discussion on the problems of technical justification for establishing a "target area" as the EPA contractor has done in framing this comment. There is no conclusive evidence at this time that a representative sample of Subunit C ground water exceeds 5.0 ppb for TCE. Unidynamics has discussed in previous comments to the EPA (letter dated July 17, 1989) the potential problems with increasing pumping rates in Subunit C and the increased drawdown associated with the pumping. A careful analysis of the relative position of the hydraulic head in Subunits A and C under any potential cleanup scenario must be completed prior to establishing design criteria for the groundwater extraction system. Failure to consider the potential adverse water quality degradation that may result from the downward migration of contaminants from Subunit A into C as a result of proposed remediation in Subunit C could lead to a remedial action that causes more of a problem than it solves.
ft g
* B
· TM · ff
g| _
«i
5. The equipment sizing and costs for the groundwater alternatives were not reviewed since by UPI's admission the sizing basis is wrong.
Response: Comment not understood. Order of magnitude costs based on preliminary design have been provided.
»
^ B m -
' '
Several statements have been made which infer that Unidynamics have failed to "...address the entire range of contaminants at the site..., not just TCE." Please refer to Table 3.6 of the May 4, 1989 RI, where eleven VOCs other than TCE are listed as being detected in monitor wells. The range of concentrations found (in ppb) is also listed in this table.
ff ^
M · _. ·
^9
In CH2M Hill's comments dated March 23, 1989, comment No. 4 ..."The results for acetone and other organic compounds are not of as much interest because they are not major components of measured ground water contamination at UPI. The exception is MEK which was found at high concentrations at UMW-4". Thus, the level of concern seen in these most recent CH2M Hill comments seems unwarranted.
*»ASVA'nf/~*IJ OU U^ 1 1 f* A*»**Mn ** *· 0 £*f*Amt* f t « . ·«·»»"»· ^ #1 ^ «4j4 r »
I i
Case 2:03-cv-02226-ROS Document 81-12 Filed 06/27/2006 Page 20 of 31
Responses to CH2M Hill
I I I I I
comments dated 7/6/89 Page 3
Furthermore, of the eleven VOCs detected in groundwater in Subunit A, other than TCE, the only VOC detected in any appreciable concentration is Methyl Ethyl Ketone (MEK). MEK is also the only "contaminant" found that is not easily treated, especially by air stripping. Air stripping for removal of TCE will, to a sufficient extent, remove the other "contaminants" as well. Studies performed with "mixtures" of VOCs present in the "ppm" range in feedwater to air strippers showed no effect on the mass transfer of each caused by the mutual presence of the others.
However, due to the presence of MEK, and the potential for traces of other VOCs, remedies beyond air stripping were examined.
6.
I I I I I I I I f I I I I f
8.
The supplements do encompass some additional alternatives for remediation of the site, but they fail to address some of the other shortcomings of the main text. In some cases they contradict the main text. They also suffer from the fact that in many cases they still do not address the entire range of contaminants at the site.
Response: In CH2M Hill's comments dated March 23, 1989, comment No. 4 ..."The results for acetone and other organic compounds are not of as much interest because they are not major components of measured ground water contamination at UPI. The exception is MEK which was found at high concentrations at UMW-4." (See response to comment No. 5)
7.
UPI has assumed that an air stripper with a GAC polishing bed is required. The reasoning for this is not at all clear. The southern portion of the site does not require GAC polishing to meet ARARs or background levels. There are contaminants at the DPI site not found in the south area, but UPI has chosen to disregard any mention of these contaminants with the exception of MEK which they state will not be treated. The treatment train described will remove VOCs if designed properly (and will apparently reduce MEK levels to some degree), but an analysis should be undertaken addressing all the contaminants at the site, not just TCE. Response: In CH2M Hill's comments dated March 23, 1989, comment No. 4 ..."The results for acetone and other organic compounds are not of as much interest because they are not major components of measured ground water contamination at UPI. The exception is MEK which was found at high concentrations at UMW-4." (See response to comments No. 5 and 6) It was because an analysis was performed which did address all the contaminants at the site, not just TCE, which lead to the need for GAC polishing following the air stripper. It is not practical to assume identical parameters between the northern and southern portions of the site. The text describes the air stripper as a "three-stage system." the meaning of this is not clear. The text also fails to address the effect that high TDS levels may have on the operation of the air stripper and the polishing bed. The text includes no explanation of the fact that TCE levels used for design purposes are above the solubility limit nor of the effect this will have on the treatment train. If free product is present, then separation may be appropriate prior to the air stripper.
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 21 of 31
Responses to CH2M Hill comments dated 7/6/89 Page 4
-
--,
· ^
Lastly, the text states that the vapor phase carbon is regenerated offsite. If the investment in regeneration facilities is to be made,
then why not regenerate all the carbon onsite?
o "Three stage system" should be interpreted as an air stripper system comprised of three air strippers in series. The text will be amended to this wording to avoid confusion.
'M TM
tt m
o o
Please also refer to our response to the 3/23/89 CH2M Hill comments; comment number 23. A compound can be removed from the liquid feed to an air stripping unit only if it can move with the vapor phase under the operating condition with in the stripping unit. TDS are not capable of doing this and so the TDS concentration in the contaminated liquid phase will remain unchanged throughout the air stripping unit. For carbon adsorption to be most successful, the target molecule should be relatively small and insoluble in water. TDS are large relative to the carbon pore spaces in which carbon adsorption occurs and, by definition, they are soluble in water. Neither listed criteria for successful carbon adsorption is met and, as with air stripping, TDS concentrations are unaffected. We agree with CH2M Hill's concern as regards the potentially adverse effect that high TDS levels may have on the operation of the air stripper and polishing bed. The Langelier Stability Index ( S ) for LI Subunit A is positive indicating the potential for scaling is very
f
,f| jg j» ^ · TM M w ·
o
o
real.
Further
calculations
indicate
that
the use of a scale
^
· TM M m ·< m TM
inhibitor such as sodium hexametaphosphate, or Flocon 100, does not reduce the potential for scaling appreciably. o o A cost for water pretreatment was included in the O&M cost estimates. The solubility of TCE in water is 1,100,000 ppb or 1,100 ppm (The Hazardous Waste Consultant, November/December 1 8 ) 9 6 . The units used in the text to express TCE concentration levels are ppb. The design
concentrations are:
GW-A.l: 14,100 ppb TCE maximum GW-A.2: 34,000 ppb TCE maximum GW-A.3: 14 ppb TCE maximum GW-A.4: 5 ppb TCE maximum
·
It is apparent from the above that the design maximum concentrations are three percent or less of the solubility limit. It is likely that
^
the text reader/comment writer misread the concentration units in the
text.
·
I I I
Case 2:03-cv-02226-ROS Document 81-12 Filed 06/27/2006 Page 22 of 31
I t I I t I I I I I I I I t I I I I I
Responses to CH2M Hill
comments dated 7/6/89
Page 5
In conclusion, the TCE design concentrations are well below the solubility limits, thus explaining why free product separation of the groundwater treatment plant influent was not discussed. Free product separation would, in any case, be difficult to achieve at the pumping rates used in this scenario, or EPA's preferred remedy. o o The text states that the vapor phase carbon system will be equipped with a steam regeneration system to be operated on-site. The regeneration system operation is described in the following: Periodically the vapor phase carbon will be regenerated with steam. The steam will be introduced into the carbon bed and carry away adsorbed solvents from the carbon. Once outside the vapor phase carbon bed, cool water is passed over the steam piping. This condenses the steam and solvents into a liquid phase called condensate. A special condensate collection tank holds the condensate. If the concentration of solvents in the condensate collection tank is greater than the solubility limit, the solvents will coalesce in a liquid organic phase product. Special baffles in the condensate collection tank allow the liquid organic phase and the aqueous phases to be removed from the tank independently. The liquid organic phase will be removed periodically and transported off-site for incineration. Vapor phase carbon regeneration and waste streams in summary:
Vapor phase carbon - Regenerated on-site Condensed steam - Process through air stripper Condensed liquid organic phase - Incinerated off-site
o Liquid phase GAG system carbon cannot be regenerated by the regeneration system installed for the vapor phase carbon system. Liquid phase GAG carbon must be incinerated and properly processed to reactivate the carbon granules. There is only one U.S. facility permitted to incinerated and reactivate spent liquid phase GAC system carbon. The facility is off-site in Pittsburgh, Pennsylvania and liquid phase GAC carbon would be transported to the facility.
9. The soils analysis also leaves some unanswered questions. It fails to address the relative effectiveness of SVE on the full range of contaminants at the site. In contrast to the main text which prominently mentioned the placement of a cap as an enhancement for the SVE system, the need for the cap has been deleted here with no explanation.
Response:
o In the comments on the March, 1989 RI/FS as provided by CH2M Hill, specifically comment number 26 on the FS, the statement was made that "The pilot test also indicated that a cap may not be necessary".
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 23 of 31
Responses to CR2M Hill comments dated 7/6/89 Page 6 This comment by CH2M Hill was noted and used to prepare the June, 1989 supplement.
o The relative effectiveness of SVE for removal of a-contaminant is
dependent on the relative soil volatility. The concept of relative soil volatility is explained and the relative dry soil and wet soil volatilities for the range of volatile soil contaminants at the site
is presented below:
Soil volatility is dependent upon two phenomena:
the compound's
vapor pressure and the density of its vapor relative to air (its buoyancy). The soil volatility property does not incorporate the
compound's Henry's Law Constant. Assumptions as to treatability by
SVE are dependent on relative soil volatility and are completely removed from assumptions as to 'treatability by "air stripping. Prejudices developed about certain compounds because of their inability to be removed by air stripping must be avoided when analyzing the effectiveness of soil vapor extraction. A compound's relative soil volatility is proportional to its vapor pressure and inversely proportional to a root of its molecular weight (The Hazardous Waste Consultant, November/December, 1986). The relative soil volatilities for all VOCs detected during Stage I and Phase II soils testing except ethylbenzene are listed below. Relative Volatility Dry Soil____Wet Soil
I
_ ·
1,1,1-Trichloroethane Trichloroethylene Xylene(s) Acetone
Methyl Ethyl Ketone
3 . 3 9 2 . 1 5 0.99-2.05 0.27-0.31 7 . 2 5
(Hazardous Waste Consultant)
1 . 0 1 6.3 1 2 . 6 3
3 . 0 51 . 0 6
I
It is apparent that all compounds are treatable with SVE where the soil volatility property is used to remove the contaminant from the soil. Although the values for xylene appear low they are still in the moderate range of effectiveness. o The operation of an SVE system is expected to dry the soil within the radius of influence, particularly in a desert climate. The operation of the system will induce the affected area to exhibit the greater dry soil volatilities. Some theorists would entertain that the contaminant would be air stripped from a water phase on the surface of the soil particles. This would have the effect of limiting the rate of removal for some compounds. The drying action of the SVE system operation would remove this phase.
I 1
^ · P V
o The decision as to whether to place a cap over the Target Areas is considered a design detail to be addressed during final design if this alternative is implemented.
I I
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 24 of 31
Responses Co CH2M Hill
comments dated 7/6/89
Page 7
10. The location of the soil contamination seems optimistic in light of the sparse soil data collected to rely on one well at each source area as
sufficient for remedial purposes. While it is true that the radius of influence was extended to distances of 150 feet during the pilot test, the effectiveness of the well at those distances is much reduced due to dissipation of the air flow at that distance. With this combination of sparse soil data and unpredictable SVE performance, it would be prudent to install additional wells and overlap their radius of influence rather than assume that one well will be sufficient. The analysis also seems to have ignored the need for some method of evaluating the SVE radius of influence and the need for evaluation of soil concentrations following installation and operation of the system. Installation of soil gas
monitoring wells would be appropriate.
I I
Response:
o Regarding the comment on the optimism suggested by designing the soil alternatives on "sparse soil data", Mr. Rosenbloom required the
i I I t I I I I
analysis be conducted to the degree prescribed regardless of the lack of data for basis.
o In the PGA SVE Pilot Study, 99% of the air removed from the uncapped site extraction well was removed from within 200 feet of the extraction well (Appendix S, p. 131).
Each SVE extraction well has been located at the center of the highest maximum predicted mean TCE concentration in the vadose zone (Figure 1 6 . The SVE extraction well will be most effective in .) these locations, exerting the greatest vacuum nearer the well.
o
o
In the comments on the March, 1989 version of the RI/;FS, Unidynamics was criticized for using a 75-foot radius of influence; inferring that the 75-foot radius was too conservative. This comment made further reference to the SVE pilot test at the southern end of the PGA site and inferred that a 150-foot radius of influence was perhaps more appropriate. The comment was noted and used to prepare the June supplement. (See Comments on the March, 1989 RI/FS by CH2M Hill;
comment number 26. Page 5-10,
influence.
Section 5.2.2.1).
The air inlet wells will be used to evaluate the SVE radius of
A field determination will be made as to whether a
150-foot or greater radius of influence has been attained.
o A method to evaluate the effectiveness of the SVE system is dependent upon the soil cleanup standards. The PGA soils sub-committee is
i I i i
still evaluating soils cleanup standards. It is not possible to design a system to evaluate cleanup effectiveness until the cleanup
standards have been defined. This is a design detail that will be
addressed
in
the
final
design
task
if
this
alternative
is
implemented.
Case 2:03-cv-02226-ROS
Document 81-12
Filed 06/27/2006
Page 25 of 31
Responses to CH2M Hill comments dated 7/6/89 Page 8
SPECIFIC COMMENTS
I 1
tt ·'
** If TM V (·
fit
Page 2S-1--Bullets: The area in the vadose zone that contains 99 percent of VOC contamination should be a target area.
Response:
o
o
The basis for identifying target areas was specified in a letter from Hugh Barroll (EPA) to M. Corash dated May 10, 1989.
The area in the vadose zone that contains 99 percent of the VOC contamination was never mentioned as a criterion in the letter or in subsequent directions from EPA.
Page 2S-2--Top of Page: The conversion of ug/1 TCE soil gas to ug/kg TCE in soil is based on assumed porosity and bulk density values. To make absolute conversions with assumed values for soil properties is incorrect.
Response: o
o
Commentator must be referring to 'Page 2S-4--Last Paragraph', where the conversion is discussed.
The conversion was requested by Jeff Rosenbloom of the EPA.
'IT TM
uf/
Page 2S-B--Last Paragraph-Interpretation; Other VOCs arelpresent in the soils at UPI, including MEK, TCA, xylenes, ethyl benzene, toluene, and acetone. Of these compounds, MEK and acetone may be difficult to extract with SVE. The presence of compounds listed are generally associated with the occurrence of TCE, except for the borings in the vicinity of Waste Facilities 7 and 11, the drum storage a
United States Free Forms
Canada Free Forms
United Kingdom Free Forms
Australia Free Forms