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| Clips & Notes on the City of Simi Valley’s TETRA TECH REPORT |
[These clips are what stood out as particularly noteworthy in this August 14, 2007 88-page Tetra Tech report with
the parts that stand out underlined. Our notes are in italics.]
PAGE:
2.
Tetra Tech’s evaluation indicated that the surface water sample collected on July 2, 2007, was not corrosive, and that
most of the comparisons of the May 18, 2007, sample results to regulatory criteria were accurate. However, Tetra Tech
also indicated that applying the regulatory criteria for drinking water to the surface water of Runkle Canyon may not be
appropriate.
Potential human consumption of surface water is reasonably possible under the Municipal and Domestic Supply, Water
Contact Recreation, and Non-contact Water Recreation beneficial use scenarios. In these types of situations, water
quality criteria, such as the MCLs, PRGs, PHGs, and NLs, may be used as screening values to determine whether further
evaluation of surface water may need to be considered. In addition, it may be necessary to determine if the surface water
or groundwater are brackish and contain high concentrations of total dissolved solids (TDS) to the point of being
considered non-potable, since the potential beneficial use designation may be changed by the LARWQCB.
3.
Split samples of surface water and soil were analyzed by Pat Chem under contract to the City and by AETL under
contract to Tetra Tech.
4.
The concentrations of metals detected in the July 2, 2007, upstream sample analyzed by AETL are generally slightly
lower than those detected in the sample analyzed by Pat Chem. Notably, the detected concentration of arsenic in the
sample analyzed by AETL (0.057 mg/L) is about half of that detected in the sample analyzed by Pat Chem (0.12 mg/L).
[The most important number ignored here is Tetra Tech’s result of 0.18 mg/l which is 25% higher than the Radiation
Rangers’ results from the same sampling locations.]
Only arsenic and chromium exceed their MCLs, while these and other metals exceed the risk-based screening levels,
such as the tap water PRGs.
[“Only”?]
5.
Soil:
In the split samples collected on July 2, 2007, only one metal (arsenic at 8.00 mg/kg in the sample analyzed at AETL)
exceeded the EPA Region 9 residential PRGs.
Only one metal (arsenic) detected in one soil sample collected May 18, 2007 sample and analyzed by Pat Chem, had a
concentration exceeding both the residential PRG and the UC Soil Background Concentration.
Also, since different metal concentrations were reported for surface water samples taken within minutes of each other at
the same location, a larger sample set may be necessary to determine relationships, if any, between the analytical
results and sample locations.
6.
When the concentrations of metals detected in the surface soil samples collected on May 18 and July 2 2007 are
compared to the UC Soil Background Concentrations, all of the metals—with the exception of cadmium—are within the
range of detected natural concentrations.
The arsenic concentration in the surface soil sample collected by Pat Chem on May 18, 2007, in which arsenic was
detected at 34 mg/kg is approximately 4 times the concentration of the sample with a quantified concentration collected
on July 2. The reason for this difference is not known, although the reported concentration also exceeds the UC Soil
Background Concentrations. One possibility may be a difference in sample collection. It is not known how the May 18
sample was collected. However, if the sample was collected from the crusts around the streambed, a sample from soils
with a high percentage of the crust could potentially contain higher metals concentrations than samples derived from
soils with a low percentage or no crust.
[“It is not known how the May 18 sample was collected”? Not only did the City use the same Pat-Chem Labs technician to
sample, there are photos of the sampling on EnviroReporter.com that show where the May 18 sampling took place.]
Further evaluation of metal concentrations in the crusts observed along the streambed may be necessary to determine
whether the arsenic concentrations in the sample collected May 18, 2007 are associated with this material. This
information could be used to determine the potential for future residential exposures to metals of potential concern, such
as arsenic, and also to guide the procedures for implementing best management practices for dust control during Site
development.
7.
To quantitatively evaluate the threat to public health and safety posed by the arsenic and other metals in surface water
and surface soil at the Site, additional evaluations should be performed to determine:
• Surface water and groundwater quality in the vicinity of the Site, particularly with regard to conditions where
groundwater may discharge to surface water;
• Factors related to differences in upstream and downstream surface water quality, such as surrounding formations (i.e.,
natural or quarry deposits) or disposed materials (e.g., pipelines);
[No mention of Rocketdyne as a potential source of arsenic and heavy metals.]
• Whether the soil sample in which arsenic was detected at 34 mg/kg is representative of soils across the Site or of the
potentially limited areas of crusts deposited along the stream; and
• Background levels of metals, particularly arsenic, in soils for the area.
[While the ‘mean’ concentration of arsenic on SSFL has been calculated on StopRunkledyne’s “Runkledyne Arsenic”
page, we have determined that, even with Rocketdyne’s extensive arsenic contamination, the Tetra Tech arsenic result in
soil of 8 mg/kg is 8.00/5.246 which means Runkle’s average arsenic is 153% of SSFL’s average arsenic concentration.]
RECOMMENDATIONS
Tetra Tech recommends further study to evaluate:
• Surface water and groundwater quality in the vicinity of the Site, particularly with regard to conditions where
groundwater may discharge to surface water;
• Factors related to differences in upstream and downstream surface water quality, such as surrounding formations (i.e.,
natural or quarry deposits) or disposed materials (e.g., pipelines);
[Rocketdyne isn't, again, mentioned as a possible factor.]
• Factors, such as evaporation, potentially contributing to “crusts” observed along the streambed and the effects on
metal concentrations observed in soil samples; and
• Background levels of metals, particularly arsenic, in soils for the area.
The study results could then be used to perform a human health screening evaluation for metals concentrations in
surface water and soil. Based on the results of this human health screening evaluation, the potential risks to humans
from exposure to the metals in surface water and soil at the Site could be determined.
[It isn’t clear what this means.]
8.
The samples were collected by Pat Chem under contract to the City. Split samples were obtained; one sample set was
analyzed by Pat Chem under contract to the City and the other sample set was analyzed by American Environmental
Testing Laboratory (AETL) under contract to Tetra Tech. The samples were analyzed to evaluate metal concentrations
in surface water and surface soil at the Site. Tetra Tech was retained by the City to observe the July 2, 2007, sample
collection, analyze a set of split samples, and evaluate the analytical data.
9.
A portion (two pages) of the Pat Chem analytical report for the sample collected on May 18, 2007 was also posted on the
EnviroReporter website. The full report was subsequently posted on the EnviroReporter website, but the additional
information is not relevant to this analysis. The partial laboratory report contained the results of analyzing a surface
water sample (sample I.D #3 0705319-01) and a top soil/mud sample (sample I.D #3 0705319-02) for metals. The
sample locations were not documented in the Los Angeles City and Valley Beat article or on the EnviroReporter website.
[“additional information is not relevant” – That is correct yet the City Council and media repeatedly claimed otherwise in
an attempt to cast doubt on the Radiation Rangers’ numbers. Ironically, the city’s retesting of the same spots yielded
higher results of toxic heavy metals probably due to the increased sensitivity of their lab’s instruments thereby further
validating the Rangers’ results.]
[ “locations were not documented” – This fails to note that not only did Radiation Ranger Rev. Southwick guide the group
to the same sample spots at the request of the city, to be tested by the same lab technician; the whole May 18 sampling
has been posted on the EnviroReporter.com website for months.]
10.
Sodium has an EPA Drinking Water Advisory drinking water taste and odor threshold level of 30 milligrams per liter
(mg/L) to 60 mg/L (Marshack 2003).
The concentration of nickel detected in the surface water sample collected on May 18, 2007, was 0.03 mg/L. The June
21 article states that “Nickel was over 12 times the EPA’s public health goal in water”. U.S. EPA does not have an MCL
for nickel and does not provide public health goals. However, a nickel concentration of 0.03 mg/L is 2.5 times the
Cal/EPA PHG of 0.012 mg/L.
The concentration of vanadium detected in the surface water sample collected on May 18, 2007, was 0.09 mg/L. This is
1.8 times the California State Notification Level of 0.05 mg/L, as stated in the article.
[There has been no indication that the City of Simi Valley has notified the local water company or the Regional Water
Quality Control Board of this as required by state law.]
10.- 11.
The concentration of arsenic detected in the surface soil sample collected on May 18, 2007, was 34 milligrams per
kilogram (mg/kg). This is 548 times the California modified U.S. EPA Region 9 PRG for residential soil of 0.062 mg/kg (U.
S. EPA Region 9 2004) and 213 percent of the DTSC field action level (FAL) (16 mg/kg), as stated in the article. The
DTSC FALs were developed specifically for the Santa Susana Field Laboratory (SSFL) Resource Conservation and
Recovery Act Field Investigation. Because the FALs were developed specifically for this SSFL investigation, additional
evaluations need to be conducted on the derivation of the FALs and whether those conditions are consistent with the
Runkle Canyon Site.
[See 12. following]
12.
If natural background concentrations are higher than the risk-based PRG concentrations, then background
concentrations should also be considered in determining whether further evaluation and/or remediation is necessary at a
particular site.” Since metals occur naturally in soils and water, background concentrations should be considered when
evaluating metal concentrations in these environmental media.
Notification levels are advisory to public water suppliers. If exceeded, CDPH recommends that the supplier correct the
problem or to find an alternative raw water source.
The DTSC Field Action Levels (FALs) were developed specifically for the Santa Susana Field Laboratory (SSFL)
Resource Conservation and Recovery Act (RCRA) Field Investigation based on soil sampling conducted by Ogden
Environmental and Energy Services Co., Inc. (Ogden) within and adjacent to the SSFL in May 1996 (MWH 2005).
Because the FALs were developed specifically for this SSFL investigation, additional evaluations need to be conducted
on the derivation of the FALs and whether those conditions are consistent with the Runkle Canyon Site.
[Runkle Canyon is not only “adjacent,” it borders SSFL]
16.
The sample locations were selected by Mr. Lovato of Pat Chem in coordination with the citizen group with the intention of
collecting samples at the same locations as during the May 18, 2007, sampling event.
[As noted on page 9, the report stated that it didn’t know where the May 18 sampling event took place yet here it does.]
20.
In general, the concentrations of metals detected in the July 2, 2007, downstream split samples are slightly higher than
those in the upstream split samples.
21.
Arsenic was detected at 8.00 mg/kg in the sample analyzed by AETL. In the sample analyzed by Pat Chem, arsenic was
not detected at a concentration above the laboratory reporting limit of 25 mg/kg (Table 2). The EPA Region 9 residential
PRG for arsenic in soil is 0.39 mg/kg and the Cal-Modified Residential PRG for arsenic in soil is 0.062 mg/kg.
[This is still 129 times the Cal-Modified residential PRG.]
When the detected results for the surface soil samples collected on July 2, 2007, are compared to the UC Soil
Background Concentration, concentrations of all of the metals—with the exception of cadmium—are within the range of
detected natural concentrations. The detected concentration of cadmium in the sample analyzed by AETL was 4.80
mg/kg, which exceeds the Background Concentration upper limit of 1.70 mg/kg. As noted above and shown in Table 2,
this cadmium concentration does not exceed the residential PRG.
21-22.
The May 18, 2007, soil sample analyzed by Pat Chem yielded arsenic at 34 mg/kg, approximately 4 times the
concentration of the sample with a quantified concentration collected on July 2. The reason for this difference is not
known. One possibility may be a difference in sample collection. It is not known how the May 18 sample was collected.
However, the surface soil samples collected on July 2, 2007, were intentionally collected from a mixture of soil in the
surface and shallow subsurface from approximately 0 to 0.5 foot bgs. The sampled soils were mixed together to
“homogenize” them before they were split into three samples. This collection process could possibly have resulted in a
different proportion of the “crust” and potentially associated substances included in the sample. A sample from soils with
a high percentage of the crust could potentially contain higher metals concentrations than samples derived from soils
with a low percentage or no crust. The surface sample soil collected on July 2, 2007, was from an area where a white
crust was present on the ground surface (Appendix B, photographs 21 through 25). It is likely that some of the crust was
included in the homogenized, spilt surface soil samples. The reasons for crust formation are not known, but may include
evaporation of the stream water or possibly precipitation of metals, such as iron, as oxygen-depleted groundwater
discharges to surface water.
[Tetra Tech may be trying to cast doubt on the May 18 sample with this disingenuous statement in order to explain away
the high arsenic reading. Furthermore, the “crust” is what humans and animals first come into contact with in these
stream bed locations.]
23.
When the concentrations of metals detected in the surface soil samples collected on May 18 and July 2 2007 are
compared to the UC Soil Background Concentrations, all of the metals—with the exception of cadmium—are within the
range of detected natural concentrations. This indicates that if the detected metals concentrations in these samples are
representative of Site soils, the metals were likely derived from natural geologic materials at the Site. The cadmium
concentration does not exceed the residential PRG.
23-24.
The arsenic concentration in the surface soil sample collected by Pat Chem on May 18, 2007, in which arsenic was
detected at 34 mg/kg is approximately 4 times the concentration of the sample with a quantified concentration collected
on July 2. The reason for this difference is not known, although the reported concentration also exceeds the UC Soil
Background Concentrations. One possibility may be a difference in sample collection. It is not known how the May 18
sample was collected. However, if the sample was collected from the crusts around the streambed, a sample from soils
with a high percentage of the crust could potentially contain higher metals concentrations than samples derived from
soils with a low percentage or no crust. The reasons for crust formation are not known, but may include evaporation of
the stream water or possibly precipitation of metals, such as iron, as oxygen-depleted groundwater discharges to surface
water.
[Again, Tetra Tech feigns ignorance when how the sample was collected May 18 was repeated July 2 by the very same
Pat Chem lab technician, Ron Lovato under the supervision of the city to repeat the sampling.]
24.
These results indicate that the exposures to a majority of the metals detected in the soil samples are similar to what
individuals may experience at other locations in California, and do not represent a potential threat to the public. Only one
metal in one soil sample (arsenic detected at 34 mg/kg in the May 18, 2007, Pat Chem sample) had a concentration
exceeding both the residential PRG and the UC Soil Background Concentration. The reason for this sample having a
higher arsenic concentration than samples collected on July 2, 2007, is not known. Given the small number of samples
evaluated in this report, the range of metals concentrations across the Site could not be determined. Further evaluation
of metal concentrations in the crusts observed along the streambed may be necessary to determine whether the arsenic
concentrations in the sample collected May 18, 2007 are associated with this material. This information could be used to
determine the potential for future residential exposures to metals of potential concern, such as arsenic, and also to guide
the procedures for implementing best management practices for dust control during Site development.
[It is unlikely that “other locations in California” are in 11-acre drainage off a former nuclear testing area that has been
mandated to be cleaned up to US EPA Superfund levels.]
Several metals in the downstream surface water sample were detected at concentrations exceeding water quality criteria.
Since drinking water is not currently obtained from the Runkle Canyon stream, nor is it anticipated that the planned
housing development will obtain drinking water from the Runkle Canyon stream, these water quality criteria exceedances
do not necessarily indicate a potential health concern for future occupants of the proposed development at the Site.
Further, since the water quality criteria are based on assumed daily exposure over a lifetime and current and future
recreational uses of this small creek are likely to be infrequent or of lesser duration, exposures and health threats are
likely to be relatively low. Nevertheless, the results suggest that further evaluation of the potential reasons for criteria
exceedances should be conducted in order to assess all potential uses of surface water in this area. For example, a
larger sample set may be necessary to determine relationships, if any, between the analytical results and sample
locations, since different metal concentrations were reported for surface water samples taken within minutes of each
other at the same location.
[Even with all the qualifiers, the report does recommend a “larger sample set.”]
To quantitatively evaluate the threat to public health and safety posed by the arsenic and other metals in surface water
and surface soil at the Site, additional evaluations should be performed to determine:
• Surface water and groundwater quality in the vicinity of the Site, particularly with regard to conditions where
groundwater may discharge to surface water;
• Factors related to differences in upstream and downstream surface water quality, such as surrounding formations (i.e.,
natural or quarry deposits) or disposed materials (e.g.,
pipelines);
• Whether the soil sample in which arsenic was detected at 34 mg/kg is representative of
soils across the Site or of the potentially limited areas of crusts deposited along the
stream; and
• Background levels of metals, particularly arsenic, in soils for the area.
26.
8.0 RECOMMENDATIONS
Tetra Tech recommends further study to evaluate:
• Surface water and groundwater quality in the vicinity of the Site, particularly with regard to conditions where
groundwater may discharge to surface water;
• Factors related to differences in upstream and downstream surface water quality, such as surrounding formations (i.e.,
natural or quarry deposits) or disposed materials (e.g., pipelines);
• Factors, such as evaporation, potentially contributing to “crusts” observed along the streambed and the effects on
metal concentrations observed in soil samples; and
• Background levels of metals, particularly arsenic, in soils for the area.
The study results could then be used to perform a human health screening evaluation for metals concentrations in
surface water and soil. Based on the results of this human health screening evaluation, the potential risks to humans
from exposure to the metals in surface water and soil at the Site could be determined.
27.
9.0 DISCLAIMER
Even a comprehensive sampling and testing program, carefully implemented with the appropriate equipment and
experienced personnel under the direction of a trained and registered professional who functions in accordance with a
professional standard of care, may fail to detect certain conditions because they are hidden, and therefore cannot be
considered in the development of a subsurface exploration program. The passage of time must also be considered, and
the client should recognize that due to natural occurrences or direct or indirect human intervention at the Site or at areas
distant from it, actual conditions may change quickly. It should be recognized that nothing can be done to eliminate risks
altogether, but certain techniques can be applied by Tetra Tech to help reduce the risks to that level deemed tolerable
by the client.
[“areas distant from it” suggests SSFL which may be an understatement.]
Since the facts forming the basis for the report are subject to professional interpretation, differing conclusions could be
reached. Tetra Tech does not assume responsibility for the discovery and elimination of hazards that could possibly
cause accidents, injuries, or damage. Compliance with submitted recommendations or suggestions does not assure
elimination of hazards or the fulfillment of client's obligation under local, state, or federal laws or any modifications or
changes to such laws.
[Tetra Tech says it is not liable for any failure of the city to adhere to the “Notification Limit” and inform the local water
company of the vanadium, and Tetra Tech says it isn’t responsible for any harm the contaminants may cause because of
this report.]
the parts that stand out underlined. Our notes are in italics.]
PAGE:
2.
Tetra Tech’s evaluation indicated that the surface water sample collected on July 2, 2007, was not corrosive, and that
most of the comparisons of the May 18, 2007, sample results to regulatory criteria were accurate. However, Tetra Tech
also indicated that applying the regulatory criteria for drinking water to the surface water of Runkle Canyon may not be
appropriate.
Potential human consumption of surface water is reasonably possible under the Municipal and Domestic Supply, Water
Contact Recreation, and Non-contact Water Recreation beneficial use scenarios. In these types of situations, water
quality criteria, such as the MCLs, PRGs, PHGs, and NLs, may be used as screening values to determine whether further
evaluation of surface water may need to be considered. In addition, it may be necessary to determine if the surface water
or groundwater are brackish and contain high concentrations of total dissolved solids (TDS) to the point of being
considered non-potable, since the potential beneficial use designation may be changed by the LARWQCB.
3.
Split samples of surface water and soil were analyzed by Pat Chem under contract to the City and by AETL under
contract to Tetra Tech.
4.
The concentrations of metals detected in the July 2, 2007, upstream sample analyzed by AETL are generally slightly
lower than those detected in the sample analyzed by Pat Chem. Notably, the detected concentration of arsenic in the
sample analyzed by AETL (0.057 mg/L) is about half of that detected in the sample analyzed by Pat Chem (0.12 mg/L).
[The most important number ignored here is Tetra Tech’s result of 0.18 mg/l which is 25% higher than the Radiation
Rangers’ results from the same sampling locations.]
Only arsenic and chromium exceed their MCLs, while these and other metals exceed the risk-based screening levels,
such as the tap water PRGs.
[“Only”?]
5.
Soil:
In the split samples collected on July 2, 2007, only one metal (arsenic at 8.00 mg/kg in the sample analyzed at AETL)
exceeded the EPA Region 9 residential PRGs.
Only one metal (arsenic) detected in one soil sample collected May 18, 2007 sample and analyzed by Pat Chem, had a
concentration exceeding both the residential PRG and the UC Soil Background Concentration.
Also, since different metal concentrations were reported for surface water samples taken within minutes of each other at
the same location, a larger sample set may be necessary to determine relationships, if any, between the analytical
results and sample locations.
6.
When the concentrations of metals detected in the surface soil samples collected on May 18 and July 2 2007 are
compared to the UC Soil Background Concentrations, all of the metals—with the exception of cadmium—are within the
range of detected natural concentrations.
The arsenic concentration in the surface soil sample collected by Pat Chem on May 18, 2007, in which arsenic was
detected at 34 mg/kg is approximately 4 times the concentration of the sample with a quantified concentration collected
on July 2. The reason for this difference is not known, although the reported concentration also exceeds the UC Soil
Background Concentrations. One possibility may be a difference in sample collection. It is not known how the May 18
sample was collected. However, if the sample was collected from the crusts around the streambed, a sample from soils
with a high percentage of the crust could potentially contain higher metals concentrations than samples derived from
soils with a low percentage or no crust.
[“It is not known how the May 18 sample was collected”? Not only did the City use the same Pat-Chem Labs technician to
sample, there are photos of the sampling on EnviroReporter.com that show where the May 18 sampling took place.]
Further evaluation of metal concentrations in the crusts observed along the streambed may be necessary to determine
whether the arsenic concentrations in the sample collected May 18, 2007 are associated with this material. This
information could be used to determine the potential for future residential exposures to metals of potential concern, such
as arsenic, and also to guide the procedures for implementing best management practices for dust control during Site
development.
7.
To quantitatively evaluate the threat to public health and safety posed by the arsenic and other metals in surface water
and surface soil at the Site, additional evaluations should be performed to determine:
• Surface water and groundwater quality in the vicinity of the Site, particularly with regard to conditions where
groundwater may discharge to surface water;
• Factors related to differences in upstream and downstream surface water quality, such as surrounding formations (i.e.,
natural or quarry deposits) or disposed materials (e.g., pipelines);
[No mention of Rocketdyne as a potential source of arsenic and heavy metals.]
• Whether the soil sample in which arsenic was detected at 34 mg/kg is representative of soils across the Site or of the
potentially limited areas of crusts deposited along the stream; and
• Background levels of metals, particularly arsenic, in soils for the area.
[While the ‘mean’ concentration of arsenic on SSFL has been calculated on StopRunkledyne’s “Runkledyne Arsenic”
page, we have determined that, even with Rocketdyne’s extensive arsenic contamination, the Tetra Tech arsenic result in
soil of 8 mg/kg is 8.00/5.246 which means Runkle’s average arsenic is 153% of SSFL’s average arsenic concentration.]
RECOMMENDATIONS
Tetra Tech recommends further study to evaluate:
• Surface water and groundwater quality in the vicinity of the Site, particularly with regard to conditions where
groundwater may discharge to surface water;
• Factors related to differences in upstream and downstream surface water quality, such as surrounding formations (i.e.,
natural or quarry deposits) or disposed materials (e.g., pipelines);
[Rocketdyne isn't, again, mentioned as a possible factor.]
• Factors, such as evaporation, potentially contributing to “crusts” observed along the streambed and the effects on
metal concentrations observed in soil samples; and
• Background levels of metals, particularly arsenic, in soils for the area.
The study results could then be used to perform a human health screening evaluation for metals concentrations in
surface water and soil. Based on the results of this human health screening evaluation, the potential risks to humans
from exposure to the metals in surface water and soil at the Site could be determined.
[It isn’t clear what this means.]
8.
The samples were collected by Pat Chem under contract to the City. Split samples were obtained; one sample set was
analyzed by Pat Chem under contract to the City and the other sample set was analyzed by American Environmental
Testing Laboratory (AETL) under contract to Tetra Tech. The samples were analyzed to evaluate metal concentrations
in surface water and surface soil at the Site. Tetra Tech was retained by the City to observe the July 2, 2007, sample
collection, analyze a set of split samples, and evaluate the analytical data.
9.
A portion (two pages) of the Pat Chem analytical report for the sample collected on May 18, 2007 was also posted on the
EnviroReporter website. The full report was subsequently posted on the EnviroReporter website, but the additional
information is not relevant to this analysis. The partial laboratory report contained the results of analyzing a surface
water sample (sample I.D #3 0705319-01) and a top soil/mud sample (sample I.D #3 0705319-02) for metals. The
sample locations were not documented in the Los Angeles City and Valley Beat article or on the EnviroReporter website.
[“additional information is not relevant” – That is correct yet the City Council and media repeatedly claimed otherwise in
an attempt to cast doubt on the Radiation Rangers’ numbers. Ironically, the city’s retesting of the same spots yielded
higher results of toxic heavy metals probably due to the increased sensitivity of their lab’s instruments thereby further
validating the Rangers’ results.]
[ “locations were not documented” – This fails to note that not only did Radiation Ranger Rev. Southwick guide the group
to the same sample spots at the request of the city, to be tested by the same lab technician; the whole May 18 sampling
has been posted on the EnviroReporter.com website for months.]
10.
Sodium has an EPA Drinking Water Advisory drinking water taste and odor threshold level of 30 milligrams per liter
(mg/L) to 60 mg/L (Marshack 2003).
The concentration of nickel detected in the surface water sample collected on May 18, 2007, was 0.03 mg/L. The June
21 article states that “Nickel was over 12 times the EPA’s public health goal in water”. U.S. EPA does not have an MCL
for nickel and does not provide public health goals. However, a nickel concentration of 0.03 mg/L is 2.5 times the
Cal/EPA PHG of 0.012 mg/L.
The concentration of vanadium detected in the surface water sample collected on May 18, 2007, was 0.09 mg/L. This is
1.8 times the California State Notification Level of 0.05 mg/L, as stated in the article.
[There has been no indication that the City of Simi Valley has notified the local water company or the Regional Water
Quality Control Board of this as required by state law.]
10.- 11.
The concentration of arsenic detected in the surface soil sample collected on May 18, 2007, was 34 milligrams per
kilogram (mg/kg). This is 548 times the California modified U.S. EPA Region 9 PRG for residential soil of 0.062 mg/kg (U.
S. EPA Region 9 2004) and 213 percent of the DTSC field action level (FAL) (16 mg/kg), as stated in the article. The
DTSC FALs were developed specifically for the Santa Susana Field Laboratory (SSFL) Resource Conservation and
Recovery Act Field Investigation. Because the FALs were developed specifically for this SSFL investigation, additional
evaluations need to be conducted on the derivation of the FALs and whether those conditions are consistent with the
Runkle Canyon Site.
[See 12. following]
12.
If natural background concentrations are higher than the risk-based PRG concentrations, then background
concentrations should also be considered in determining whether further evaluation and/or remediation is necessary at a
particular site.” Since metals occur naturally in soils and water, background concentrations should be considered when
evaluating metal concentrations in these environmental media.
Notification levels are advisory to public water suppliers. If exceeded, CDPH recommends that the supplier correct the
problem or to find an alternative raw water source.
The DTSC Field Action Levels (FALs) were developed specifically for the Santa Susana Field Laboratory (SSFL)
Resource Conservation and Recovery Act (RCRA) Field Investigation based on soil sampling conducted by Ogden
Environmental and Energy Services Co., Inc. (Ogden) within and adjacent to the SSFL in May 1996 (MWH 2005).
Because the FALs were developed specifically for this SSFL investigation, additional evaluations need to be conducted
on the derivation of the FALs and whether those conditions are consistent with the Runkle Canyon Site.
[Runkle Canyon is not only “adjacent,” it borders SSFL]
16.
The sample locations were selected by Mr. Lovato of Pat Chem in coordination with the citizen group with the intention of
collecting samples at the same locations as during the May 18, 2007, sampling event.
[As noted on page 9, the report stated that it didn’t know where the May 18 sampling event took place yet here it does.]
20.
In general, the concentrations of metals detected in the July 2, 2007, downstream split samples are slightly higher than
those in the upstream split samples.
21.
Arsenic was detected at 8.00 mg/kg in the sample analyzed by AETL. In the sample analyzed by Pat Chem, arsenic was
not detected at a concentration above the laboratory reporting limit of 25 mg/kg (Table 2). The EPA Region 9 residential
PRG for arsenic in soil is 0.39 mg/kg and the Cal-Modified Residential PRG for arsenic in soil is 0.062 mg/kg.
[This is still 129 times the Cal-Modified residential PRG.]
When the detected results for the surface soil samples collected on July 2, 2007, are compared to the UC Soil
Background Concentration, concentrations of all of the metals—with the exception of cadmium—are within the range of
detected natural concentrations. The detected concentration of cadmium in the sample analyzed by AETL was 4.80
mg/kg, which exceeds the Background Concentration upper limit of 1.70 mg/kg. As noted above and shown in Table 2,
this cadmium concentration does not exceed the residential PRG.
21-22.
The May 18, 2007, soil sample analyzed by Pat Chem yielded arsenic at 34 mg/kg, approximately 4 times the
concentration of the sample with a quantified concentration collected on July 2. The reason for this difference is not
known. One possibility may be a difference in sample collection. It is not known how the May 18 sample was collected.
However, the surface soil samples collected on July 2, 2007, were intentionally collected from a mixture of soil in the
surface and shallow subsurface from approximately 0 to 0.5 foot bgs. The sampled soils were mixed together to
“homogenize” them before they were split into three samples. This collection process could possibly have resulted in a
different proportion of the “crust” and potentially associated substances included in the sample. A sample from soils with
a high percentage of the crust could potentially contain higher metals concentrations than samples derived from soils
with a low percentage or no crust. The surface sample soil collected on July 2, 2007, was from an area where a white
crust was present on the ground surface (Appendix B, photographs 21 through 25). It is likely that some of the crust was
included in the homogenized, spilt surface soil samples. The reasons for crust formation are not known, but may include
evaporation of the stream water or possibly precipitation of metals, such as iron, as oxygen-depleted groundwater
discharges to surface water.
[Tetra Tech may be trying to cast doubt on the May 18 sample with this disingenuous statement in order to explain away
the high arsenic reading. Furthermore, the “crust” is what humans and animals first come into contact with in these
stream bed locations.]
23.
When the concentrations of metals detected in the surface soil samples collected on May 18 and July 2 2007 are
compared to the UC Soil Background Concentrations, all of the metals—with the exception of cadmium—are within the
range of detected natural concentrations. This indicates that if the detected metals concentrations in these samples are
representative of Site soils, the metals were likely derived from natural geologic materials at the Site. The cadmium
concentration does not exceed the residential PRG.
23-24.
The arsenic concentration in the surface soil sample collected by Pat Chem on May 18, 2007, in which arsenic was
detected at 34 mg/kg is approximately 4 times the concentration of the sample with a quantified concentration collected
on July 2. The reason for this difference is not known, although the reported concentration also exceeds the UC Soil
Background Concentrations. One possibility may be a difference in sample collection. It is not known how the May 18
sample was collected. However, if the sample was collected from the crusts around the streambed, a sample from soils
with a high percentage of the crust could potentially contain higher metals concentrations than samples derived from
soils with a low percentage or no crust. The reasons for crust formation are not known, but may include evaporation of
the stream water or possibly precipitation of metals, such as iron, as oxygen-depleted groundwater discharges to surface
water.
[Again, Tetra Tech feigns ignorance when how the sample was collected May 18 was repeated July 2 by the very same
Pat Chem lab technician, Ron Lovato under the supervision of the city to repeat the sampling.]
24.
These results indicate that the exposures to a majority of the metals detected in the soil samples are similar to what
individuals may experience at other locations in California, and do not represent a potential threat to the public. Only one
metal in one soil sample (arsenic detected at 34 mg/kg in the May 18, 2007, Pat Chem sample) had a concentration
exceeding both the residential PRG and the UC Soil Background Concentration. The reason for this sample having a
higher arsenic concentration than samples collected on July 2, 2007, is not known. Given the small number of samples
evaluated in this report, the range of metals concentrations across the Site could not be determined. Further evaluation
of metal concentrations in the crusts observed along the streambed may be necessary to determine whether the arsenic
concentrations in the sample collected May 18, 2007 are associated with this material. This information could be used to
determine the potential for future residential exposures to metals of potential concern, such as arsenic, and also to guide
the procedures for implementing best management practices for dust control during Site development.
[It is unlikely that “other locations in California” are in 11-acre drainage off a former nuclear testing area that has been
mandated to be cleaned up to US EPA Superfund levels.]
Several metals in the downstream surface water sample were detected at concentrations exceeding water quality criteria.
Since drinking water is not currently obtained from the Runkle Canyon stream, nor is it anticipated that the planned
housing development will obtain drinking water from the Runkle Canyon stream, these water quality criteria exceedances
do not necessarily indicate a potential health concern for future occupants of the proposed development at the Site.
Further, since the water quality criteria are based on assumed daily exposure over a lifetime and current and future
recreational uses of this small creek are likely to be infrequent or of lesser duration, exposures and health threats are
likely to be relatively low. Nevertheless, the results suggest that further evaluation of the potential reasons for criteria
exceedances should be conducted in order to assess all potential uses of surface water in this area. For example, a
larger sample set may be necessary to determine relationships, if any, between the analytical results and sample
locations, since different metal concentrations were reported for surface water samples taken within minutes of each
other at the same location.
[Even with all the qualifiers, the report does recommend a “larger sample set.”]
To quantitatively evaluate the threat to public health and safety posed by the arsenic and other metals in surface water
and surface soil at the Site, additional evaluations should be performed to determine:
• Surface water and groundwater quality in the vicinity of the Site, particularly with regard to conditions where
groundwater may discharge to surface water;
• Factors related to differences in upstream and downstream surface water quality, such as surrounding formations (i.e.,
natural or quarry deposits) or disposed materials (e.g.,
pipelines);
• Whether the soil sample in which arsenic was detected at 34 mg/kg is representative of
soils across the Site or of the potentially limited areas of crusts deposited along the
stream; and
• Background levels of metals, particularly arsenic, in soils for the area.
26.
8.0 RECOMMENDATIONS
Tetra Tech recommends further study to evaluate:
• Surface water and groundwater quality in the vicinity of the Site, particularly with regard to conditions where
groundwater may discharge to surface water;
• Factors related to differences in upstream and downstream surface water quality, such as surrounding formations (i.e.,
natural or quarry deposits) or disposed materials (e.g., pipelines);
• Factors, such as evaporation, potentially contributing to “crusts” observed along the streambed and the effects on
metal concentrations observed in soil samples; and
• Background levels of metals, particularly arsenic, in soils for the area.
The study results could then be used to perform a human health screening evaluation for metals concentrations in
surface water and soil. Based on the results of this human health screening evaluation, the potential risks to humans
from exposure to the metals in surface water and soil at the Site could be determined.
27.
9.0 DISCLAIMER
Even a comprehensive sampling and testing program, carefully implemented with the appropriate equipment and
experienced personnel under the direction of a trained and registered professional who functions in accordance with a
professional standard of care, may fail to detect certain conditions because they are hidden, and therefore cannot be
considered in the development of a subsurface exploration program. The passage of time must also be considered, and
the client should recognize that due to natural occurrences or direct or indirect human intervention at the Site or at areas
distant from it, actual conditions may change quickly. It should be recognized that nothing can be done to eliminate risks
altogether, but certain techniques can be applied by Tetra Tech to help reduce the risks to that level deemed tolerable
by the client.
[“areas distant from it” suggests SSFL which may be an understatement.]
Since the facts forming the basis for the report are subject to professional interpretation, differing conclusions could be
reached. Tetra Tech does not assume responsibility for the discovery and elimination of hazards that could possibly
cause accidents, injuries, or damage. Compliance with submitted recommendations or suggestions does not assure
elimination of hazards or the fulfillment of client's obligation under local, state, or federal laws or any modifications or
changes to such laws.
[Tetra Tech says it is not liable for any failure of the city to adhere to the “Notification Limit” and inform the local water
company of the vanadium, and Tetra Tech says it isn’t responsible for any harm the contaminants may cause because of
this report.]
