[Federal Register Volume 73, Number 54 (Wednesday, March 19, 2008)]
[Rules and Regulations]
[Pages 14687-14713]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-5188]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R09-OAR-2006-0583, FRL-8542-6]


Approval and Promulgation of Implementation Plans; Designation of 
Areas for Air Quality Planning Purposes; State of California; PM-10; 
Affirmation of Determination of Attainment for the San Joaquin Valley 
Nonattainment Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: EPA is finalizing its proposal to affirm its October 30, 2006, 
determination that the San Joaquin Valley nonattainment area (SJV or 
the Valley) in California has attained the National Ambient Air Quality 
Standard (NAAQS) for particulate matter with an aerodynamic diameter 
less than or equal to a nominal 10 micrometers (PM-10). EPA proposed to 
affirm the determination of attainment in order to take comment on the 
exclusion from a

[[Page 14688]]

determination of attainment of PM-10 exceedances that were caused by 
exceptional events. EPA is concurring with the State's request to flag 
exceedances which occurred in the SJV as being caused by exceptional 
events, i.e., high winds. EPA is also concurring with the Santa Rosa 
Rancheria Tribe's request to flag, as due to an exceptional event, PM-
10 exceedances which occurred on tribal lands located within the 
boundaries of the SJV. EPA is further finding that these exceedances at 
the Santa Rosa Rancheria (SRR) should be excluded from use in 
determining attainment because the exceedances occurred while the 
monitor was operating in very close proximity to construction 
activities and, as such, the monitor was not properly sited during that 
time for purposes of comparison to the NAAQS. As a result, EPA is 
affirming its determination that the SJV has attained the PM-10 
standard based on EPA's evaluation of quality-assured data through 
2006.
    In addition, EPA did not receive comments on how the Agency 
addressed the issues raised in petitions for reconsideration and 
withdrawal of EPA's 2006 determination of attainment, filed by 
Earthjustice on behalf of the Sierra Club, Latino Issues Forum and 
others, and thus we are denying the petitions.

DATES: Effective Date: This rule is effective on April 18, 2008.

ADDRESSES: EPA has established docket number EPA-R09-OAR-2006-0583 for 
this action. The index to the docket is available electronically at 
www.regulations.gov and in hard copy at EPA Region IX, 75 Hawthorne 
Street, San Francisco, California. While all documents in the docket 
are listed in the index, some information may be publicly available 
only at the hard copy location (e.g., copyrighted material), and some 
may not be publicly available in either location (e.g., CBI). To 
inspect the hard copy materials, please schedule an appointment during 
normal business hours with the contact listed in the FOR FURTHER 
INFORMATION CONTACT section.

FOR FURTHER INFORMATION CONTACT: Doris Lo, EPA Region IX, (415) 972-
3959, [email protected] or Bob Pallarino, EPA Region IX, (415) 947-4128, 
[email protected].

SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us'' and 
``our'' refer to EPA.

Table of Contents

I. Summary of Proposed Action
II. Public Comments and EPA Responses
    A. Earthjustice Comments
    1. Overview Comments
    2. Comments Specific to September 22, 2006--Corcoran, 
Bakersfield and Oildale
    3. Comments Specific to October 25, 2006--Corcoran and 
Bakersfield
    B. Other Comments
    C. List of EPA Figures in the Docket
III. Final Action
IV. Statutory and Executive Order Reviews

I. Summary of Proposed Action

    On August 27, 2007, EPA proposed to affirm its determination that 
the SJV has attained the 24-hour NAAQS for PM-10. 72 FR 49046.\1\ EPA 
issued this proposed rule in order to take comment on the exclusion of 
several PM-10 exceedances that were caused by exceptional events, and, 
in the case of the SRR, improper siting of the monitor for purposes of 
comparison to the NAAQS. These exceedances are summarized in Table 1 in 
the proposed rule. Id. at 49047. For a more detailed discussion of the 
related background for the SJV and of the proposal, please refer to the 
proposed rule.
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    \1\ On October 17, 2006, EPA finalized its determination that 
the SJV attained the NAAQS for PM-10 and on October 30, 2006, EPA 
published this determination in the Federal Register. 71 FR 63642.
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II. Public Comments and EPA Responses

    EPA received three comment letters supporting the proposal to 
affirm the attainment determination. These comments were submitted by 
the California Cotton Ginners and Growers Association, the Tulare 
County Farm Bureau and the Western United Dairymen. In general, these 
commenters support the cases that are made for the exceptional event 
exceedances and discuss the many control measures and efforts that have 
been made to achieve attainment. The commenters also point to the SJV's 
continued efforts to achieve further air quality improvements under the 
PM-2.5 plan development. One commenter provides information to show 
that no cotton harvesting was occurring in September 2006. Finally, the 
commenters question the representativeness of the 2000 comment letters 
received by EPA in response to our July 19, 2006, attainment 
determination proposal (71 FR 40952) since the majority of the 
commenters appear to reside outside the SJV.
    EPA received three adverse comment letters. Two were from private 
citizens from the state of Tennessee and one was from Earthjustice, 
representing Sierra Club, Latino Issues Forum, Medical Advocates for 
Healthy Air, the Steven and Michele Kirsch Foundation, Tri-Valley 
CAREs, Concerned Residents of Lockwood Valley, Fresno Coalition Against 
the Misuse of Pesticides, California Communities Against Toxics, Fresno 
Metro Ministry, Coalition for Clean Air, Center for Biological 
Diversity, and the Association of Irritated Residents.\2\ The majority 
of the comments discussed below are raised by Earthjustice.
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    \2\ The proposal provided a 30 day comment period ending on 
September 26, 2007. EPA received a request for an additional 30 days 
to comment and granted that request extending the comment period 
until October 26, 2007. 72 FR 53743 (September 20, 2007).
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    EPA notes that although it received numerous specific comments on 
the September 22, 2006, October 25, 2006, and the SRR exceedances, no 
adverse comments are directed specifically at EPA's finding that 
exceedances monitored on December 8, 2006, at Corcoran and Bakersfield-
Golden State Highway (Bakersfield) were caused by an exceptional high 
wind event. Thus, EPA does not address any substantive issues regarding 
these exceedances in its responses to comments.
    In subsection A. below we respond to the extensive comments raised 
by Earthjustice. In subsection B. we respond to comments raised by 
other parties.

A. Earthjustice Comments

1. Overview Comments
    Comment 1: Earthjustice explains that its comments analyze EPA's 
proposed affirmation rule under the new Exceptional Events Rule (EER). 
72 FR 13560 (March 22, 2007). In this regard, Earthjustice states that, 
``assuming EPA has the discretion to apply the new rule,'' EPA's 
decision to do so is completely arbitrary given that the San Joaquin 
Valley Air Pollution Control District (District or SJVAPCD) prepared 
its analyses under EPA's prior policies and did not invoke the new 
regulatory requirements.
    Response 1: EPA addressed the issue of the applicability of the new 
EER to the events at issue in this rulemaking in its proposed 
affirmation rule. EPA explained that the statutory provision upon which 
the new rule is based, CAA section 319, as amended by section 6013 of 
the Safe Accountable Flexible Efficient-Transportation Equity Act: A 
Legacy for Users (SAFE-TEA-LU) of 2005, provides that the Agency's pre-
existing guidance documents continue to apply until the effective date 
of the rule. CAA section 319(b)(4). As mandated by section 319, EPA 
finalized and published the final EER in March 2007. This rule became 
effective on May 21, 2007, requiring EPA to follow the rule in making 
exceptional events determinations after that date.

[[Page 14689]]

Therefore, in making and publishing its determination after the 
effective date of the EER, EPA followed its procedures and criteria in 
evaluating the State's exceptional events demonstrations. 72 FR at 
49048.
    Although EPA followed the EER in this particular instance, and 
believes it should be followed in most cases, the Agency recognized 
that there might be certain instances where EPA had not yet made a 
decision on a state's already completed and submitted demonstration of 
an exceptional event and these demonstrations were thus caught 
midstream. In those instances, EPA concluded that a state could choose 
for a limited period to comply with either the provisions of the rule 
or those of the Agency's existing policies and, that if asked, EPA 
would act under the policy on a grandfathering rationale for a short 
time period. EPA continues to believe that this transitional policy was 
reasonable in the absence of an explicit statutory directive addressing 
that situation. Here, the State did not indicate that its submissions 
should be evaluated under the existing policies. Therefore, EPA applied 
the rule, which was already effective, when it made its determinations 
on the exceptional events in the SJV.
    Comment 2: Earthjustice, citing case law, states that EPA must 
provide a rational basis to support its conclusions regarding the 
exclusion of monitoring data showing NAAQS exceedances and that its 
decisions must have a ``substantial basis in facts.'' Earthjustice 
cites 40 CFR 50.14(c)(3)(iii) and CAA section 319(b)(3)(B), 
respectively, for the propositions that for EPA's determination here 
the District must provide actual evidence to support its claims and 
that the occurrence of an exceptional event must be ``demonstrated by 
reliable, accurate data.'' Earthjustice claims that even under a weight 
of evidence standard there must be evidence supporting the specific 
findings and that reliance on a plausible story is not enough.
    Response 2: EPA agrees with Earthjustice's characterization of the 
general demonstration, as stated in our summary of its comment above, 
that must be made in order to exclude data showing NAAQS exceedances. 
EPA believes that it has, both in the proposed affirmation rule and 
this final rule, provided a rational basis supported by reliable, 
accurate data for its conclusions that the September, October and 
December 2006 PM-10 exceedances in the SJV were caused by exceptional 
events. See 72 FR at 59050-49063 and our responses to comments below.
    Comment 3: Regarding its contention concerning the lack of reliable 
and accurate data, Earthjustice cites EPA's statements in the proposed 
affirmation rule at 72 FR at 49053 that activity levels on September 
22, 2006 were ``constant'' and that reasonable controls were in place 
to control particulate matter while providing only general or anecdotal 
evidence in the form of non-specific District inspector observations 
and ``discussions with representatives of agricultural and industrial 
operations.'' Citing CAA section 319(b)(3)(B), Earthjustice claims that 
this does not satisfy the statutory requirement that ``exceptionality'' 
be based on reliable, accurate data.
    Response 3: In the section of the proposed affirmation rule cited 
by Earthjustice we discussed our conclusion that the State's 
documentation demonstrates that the exceedances at Corcoran, 
Bakersfield and Oildale on September 22, 2006 would not have occurred 
but for the wind event on this day. EPA based this conclusion on the 
totality of the evidence presented by the State which included, but was 
not limited to, the information on activity levels and control measures 
singled out by Earthjustice. For the additional factors EPA considered 
in reaching its conclusion, see section V.A.2.d. in our proposed 
affirmation rule (72 FR at 49053) and our responses to comments below.
    Comment 4: Earthjustice claims that EPA offers no evidence to 
support the construction claims regarding the SRR. It asserts that EPA 
cannot say what if anything was occurring on the days in question, 
where it was occurring, or why it could not be reasonably controlled. 
Earthjustice also maintains that EPA cannot show that construction 
activity at the SRR is related to the measured exceedances and, as a 
result, EPA cannot show the required ``clear causal relationship.'' 
Further, EPA cannot say when these events occurred and why these 
allegedly ongoing activities only resulted in exceedances during the 
same period that monitors in other areas of the SJV started monitoring 
exceedances. Earthjustice argues that EPA cannot make the required 
``but for'' showing at the SRR because EPA cannot show that there was 
an event in the first place. Earthjustice further contends that EPA did 
not provide adequate evidence, including written accounts, that the 
construction activity took place on the days the exceedances occurred. 
Earthjustice claims that ``no one was able to produce any written 
account, in the form of contractor records, work orders, schedules, or 
anything else that would confirm that construction activity did, in 
fact, take place on the days in question.'' Finally, Earthjustice 
states that ``mere post hoc speculation and anecdotal accounts of what 
probably happened does not establish a basis for waiving these data.''
    Response 4: First, Earthjustice notes that EPA proposed to exclude 
the SRR violations on two grounds: (1) The monitor was not properly 
sited, and (2) the nearby construction activity was an exceptional 
event. Earthjustice concedes that ``[b]oth of these conclusions seem 
reasonable if the activity can be shown to have occurred on the days 
the monitor recorded violations.'' Earthjustice Comments (EC) at 23.\3\ 
Earthjustice contends, however, that EPA did not provide ``any such 
evidence.''
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    \3\ Earthjustice concedes, moreover, that under the EER the 
requirements for tribal governments appear to be ``much more 
flexible * * * '' and ``[i]t would not take much to make these 
demonstrations.'' EC at 22.
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    Contrary to Earthjustice's assertion, EPA in its proposed 
affirmation rule provided a demonstration that construction activity, 
involving the grading and paving of parking lots, took place in close 
proximity to the SRR monitor during the period the exceedances at the 
SRR monitor occurred, and that this activity caused the exceedances. 
EPA in its proposal set forth information derived from eyewitness 
accounts, meteorological data, contemporaneous tracking reports, and an 
account of an EPA expert's own visit to the site. 72 FR at 49060-49063. 
EPA did include written documentation of the events at issue. This 
written documentation included sample tracking reports that accompanied 
the filters from the monitors and described the conditions at the time 
of the monitoring, and an EPA expert's report of his site visit and 
interviews of witnesses to the events. There is no requirement in the 
EER that documentation of events include specific types of written 
documentation, such as those cited by Earthjustice.\4\ Nor

[[Page 14690]]

is there any requirement for specific types of documentation for EPA to 
demonstrate its alternative ground for excluding the data under 
principles established in 40 CFR part 58, appendix E, that during the 
period of the nearby construction the monitor was not properly sited 
for purposes of collecting data for comparison to the NAAQS. 72 FR at 
49060-49061.
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    \4\ Note that we are not specifying what will be required as a 
minimum level of documentation in all cases because facts and 
circumstances will vary significantly based on, among other things, 
geography, meteorology and the relative complexity of source 
contributions to measured concentrations in any particular location. 
72 FR at 13573. A particular instance may require more or less 
documentation, depending on the particular facts or circumstances. 
The simplest demonstrations could consist of newspaper accounts or 
satellite images to demonstrate that an event occurred together with 
daily and seasonal average ambient concentrations to demonstrate an 
unusually high ambient concentration level, which is clearly 
indicative of an exceptional impact. Such is the case with events 
such as volcanic eruptions and nearby forest fires. Id. More 
documentation would be needed to support situations that are not as 
straightforward.
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    EPA's findings were supported by information from interviews with 
three individuals with firsthand knowledge of the activities that took 
place near the monitor, as well as by contemporaneous documentation 
from filter sample tracking reports. These individuals were the SRR 
environmental technician responsible for overseeing the operation of 
the monitor, the SRR construction superintendent, and a private 
environmental consultant working for the Santa Rosa Rancheria EPA 
(SRREPA). The construction superintendent and the consultant concurred 
with the SRR environmental technician's recollection that grading and 
paving of the parking lots took place in September and October 2006, 
and the environmental technician concluded that these activities caused 
the exceedances on September 14 and 20, 2006 and later in October, when 
the initial paving had to be removed and the parking lot repaved.
    EPA's July 18, 2007, Memorandum, ``On-Site Visit to Santa Rosa 
Rancheria,'' from Bob Pallarino, EPA, to Sean Hogan, EPA (Site Visit 
Memorandum), contains the following account:

    The construction activity entailed grading and leveling the 
ground, application of sub-base material, and paving with asphalt. 
The par[k]ing lot was first paved in September and it is this 
project which [the SRR environmental technician] believed caused the 
exceedances on September 14 and 20. * * * the first paving * * * had 
to be removed and the parking lot repaved.\5\ It is this second part 
of the paving project which [the environmental technician] believed 
caused the October exceedance. * * * [T]he SRR environmental 
consultant stated that he had witnessed these construction 
activities during September and October, 2006. * * * The 
construction supervisor concurred with [the environmental 
technician's] recollection of the construction activity * * *.
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    \5\ The Site Memorandum stated that the first paving project 
``did not pass inspection and the paving had to be removed and the 
parking lot repaved.'' The Facility Manager in his letter of 
December 2007 referred to the first paving of the parking lot as 
``temporary.''

Site Visit Memorandum at 2-3.
    The information about the timing of the construction activity, from 
witnesses with both firsthand and expert knowledge, is confirmed by 
documentation from the California Air Resources Board (CARB) sample 
tracking reports that the SRREPA environmental technician filled out at 
the time the samples were obtained, and forwarded to CARB along with 
the monitored samples. The SRREPA technician observed the ``sampling 
conditions'' at the time the monitor was operating and noted on the 
sample tracking forms, which are completed with each sampling run, that 
there was ``construction nearby.'' This was signified by the letter 
``J''. Earthjustice ignores this corroborating documentation, cited by 
EPA in its proposal, and included in the rulemaking docket. 72 FR at 
49062. It is significant that these sample tracking forms were prepared 
before the filters from the monitors were sent to and analyzed by the 
lab. Thus at the time the technician noted that nearby construction was 
occurring during the monitoring, he could not have known whether or not 
an exceedance was recorded that day.
    EPA's proposal also showed that the meteorological data lend 
support to the environmental technician's account of the events of the 
days in question. The winds on the three days that exceeded the NAAQS 
were predominantly from the northwest, north and northeast. This would 
indicate that any dust-producing activity north and northeast of the 
monitor would result in high concentrations of geologic dust being 
blown towards the monitor. Site Visit Memorandum at 2.
    Further corroboration of the impact of the construction on the 
monitor came from EPA's assessment of the proximity of the monitoring 
site to the nearby parking lots. EPA's onsite inspection ascertained 
that one of the parking lots was within 25 feet of the monitor, and the 
other was within 100 feet. 72 FR at 49062.
    Reinforcing EPA's conclusion that construction activities near the 
monitor caused the exceedances was the fact, pointed to in the proposed 
rule, that after completion of the paving projects, average PM-10 
concentrations dropped by more than 50 percent. Id.
    Since the proposal, EPA has obtained further documentation that the 
exceedances occurred during the period of construction activity in 
close proximity to the monitor. The Facility Director of the Tribe's 
hotel and casino has provided EPA with a letter stating that asphalt 
work on the parking lots close to the monitoring station was completed 
between August 15 and November 4, 2006. Enclosed with the letter was a 
billing statement from the Tribe's general contractor for the period up 
to August 15, 2006. The statement shows that work on the parking lots 
close to the monitor remained to be completed after August 15. The 
letter from the Facility Director states that at the time of the 
monitored exceedances, there were earthmoving activities nearby and 
paving activities near the site of the monitor ``in a large area for 
parking for Tribal Administrators and for our customers.''
    Thus, in addition to the documentation available at the time of the 
proposal, EPA has provided a letter from the Tribe and a billing 
statement from the general contractor that support the conclusion that 
paving work was occurring at the time of the exceedances.
    Earthjustice argues that because exceedances did not occur on other 
days when construction activities were occurring, this indicates that 
construction did not cause the exceedances in September and October 
2006. But this argument is misleading. Generally, varying degrees, 
types and locations of the construction activity, and changing 
meteorological conditions lead to varying impacts on the monitor. The 
fact that construction activities did not cause exceedances on some 
days does not mean that they were not responsible for the exceedances 
that occurred on other days. In addition, although Earthjustice claims 
that two days of violations at the SRR ``correlate well with violations 
seen in other parts of the Valley,'' no other violations were monitored 
in the Valley on September 14 and 20 and October 26, 2006.
    Earthjustice also claims that EPA ``still needs to make the other 
required showings'' for exceptional events, ``including that these 
sources were reasonably controlled.'' EC at 22. EPA made these showings 
in its proposal, and Earthjustice did not raise any specific grounds to 
challenge them. See 72 FR at 49061-49062. In its proposal EPA, after 
discussing whether the construction activity's impact on the monitor 
was reasonably controllable, concluded that ``under the particular set 
of circumstances presented here, for the purposes of evaluating the 
`reasonably controllable' criterion of the EER, we deem this criterion 
to have been satisfied.'' EPA found that even if control measures had 
been employed, we cannot be certain they would have prevented 
exceedances at the monitor, and that EPA's monitor siting rules provide 
that the monitor should not be operated at such a time and place for 
the purposes for determining attainment. 72 FR at 49062. We note that 
the criteria under the EER do not apply for the

[[Page 14691]]

purposes of our alternative ground, that the monitor was not properly 
sited. See 72 FR at 49060-49061. Thus EPA is finalizing its 
determination that there are two independent bases for determining that 
the exceedances recorded at the SRR in September and October, 2006 
should be excluded from consideration in determining whether the SJV 
has attained the PM-10 standard: (1) The monitor was not properly 
sited, under the principles established in part 58, appendix E, and (2) 
the construction activity constitutes an exceptional event under EPA's 
EER.
    Comment 5: Earthjustice states that EPA cannot point to any 
statutory or regulatory authority that allows it to treat wind-
entrained particulate matter pollution from land that has been 
disturbed by human activities, i.e., agriculture or construction as 
``natural.'' Earthjustice observes that, while EPA cites preamble 
language in the EER regarding high winds, this language was never 
codified even though the final rule does contain provisions relating to 
the treatment of other anthropogenic sources such as fireworks and 
prescribed fire. Earthjustice suggests that even though a natural event 
is defined in 40 CFR 50.1(k) as ``an event in which human activity 
plays little or no direct causal role,'' EPA attempts to define an 
event in which wind-entrained dust from agricultural and industrial 
operations as natural. Earthjustice cites legislative history of the 
1990 Clean Air Act Amendments (CAAA) to support its contention that 
this result defies logic and flies in the face of Congressional intent 
as evidenced by Congress's refusal to excuse dust storms from Mono and 
Owens lakebeds because they were human-caused. Earthjustice claims that 
if the measures in place are not enough to prevent exceedances due to 
wind-entrained dust, then Congress intended that additional controls be 
required.
    Response 5: Section 319, as amended, defines an exceptional event 
as an event that affects air quality, is not reasonably preventable or 
controllable, is a natural event or is an event caused by human 
activity that is unlikely to recur at a particular location. Under this 
definition, for an event to qualify as an exceptional event, both 
natural events and events caused by human activity must be events that 
are not reasonably preventable or controllable. Therefore, 
Earthjustice's conclusion that designating an event ``natural'' would 
``allow air agencies to avoid controls'' is erroneous. An agency 
flagging data as due to an exceptional event, including a high wind 
event, will be required to show that the event was not reasonably 
preventable or controllable. In the preamble to the final rule, EPA 
explained how it would evaluate whether an agency had been able to 
successfully demonstrate that an event met this criteria by taking into 
account the controls in place, the wind speed, and other factors. 72 FR 
at 13565-13566, 13576-13577. As explained elsewhere in our responses to 
comments below, in this particular instance the District's Regulation 
VIII (general fugitive dust rules) and Rule 4550 which limits fugitive 
dust emissions specifically from agricultural operations through 
Conservation Management Practices (CMPs) were in place. In addition, 
the District has adopted and is implementing EPA-approved best 
available control measures (BACM) for all significant sources of PM-10 
in the SJV.
    Earthjustice incorrectly states that if an event is classified as a 
natural event, a state would be able to ``avoid controls.'' In the 
proposed EER, EPA explained that it was proposing to treat high wind 
events that result in exceedances or violations as a natural event 
provided a clear causal relationship between the wind event and the 
measured exceedance was established and contributing anthropogenic 
activities were ``reasonably well-controlled.'' \6\ In the final rule, 
after considering the comments on high wind events including on the 
terminology and the definition, EPA adopted an approach that considers 
high winds a natural event if contributing anthropogenic activities are 
controlled through ``reasonable and appropriate measures.'' 72 FR at 
13566. To qualify as a natural event (a subset of exceptional events 
under the rule) a state must demonstrate, among others, that dust from 
contributing anthropogenic sources was ``reasonably well-controlled at 
the time the event occurred.'' 72 FR at 13576. The EER, therefore, has 
already defined what constitutes a high wind event through appropriate 
notice and comment rulemaking. Thus, the question of whether a high 
wind that causes exceedances or violations due to entrainment of dust 
from anthropogenic sources can be defined as a natural event is not an 
issue that is open for comment in this rulemaking. In this case, the 
Agency has only asked for comments on whether the particular high wind 
event met the criteria and procedures established under the rule, e.g., 
establishing a causal connection, reasonable controls on anthropogenic 
sources, wind speed and direction, etc., and not on whether these 
criteria are appropriate.
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    \6\ EPA made this statement in the context of PM-2.5 because at 
the time, the Agency was considering adopting the PM10-2.5 standard 
and noted that states would be expected to have appropriate controls 
for contributing anthropogenic emissions under the definition of the 
proposed PM10-2.5 indicator. The Agency, eventually, did not 
finalize the PM10-2.5 indicator and instead retained the 24-hour PM-
10 standard.
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    Earthjustice cites to the legislative history of the 1990 CAAA, for 
the discussion on Owens and Mono lakebeds where Congress indicated that 
diversion of water from these lakes created an anthropogenic source of 
dust. From this Earthjustice contrives an overly-broad conclusion that 
any ``dust from lands disturbed by human activity'' must be treated as 
an anthropogenic rather than a natural event. Under this proposition 
gale-force winds, for example of 100 mph, in an urban area could not be 
treated as a natural event because human activity would be a 
contributing factor.
    As a matter of record, the legislative history also demonstrates 
that EPA concurred with Congress that the diversion of water created an 
anthropogenic source of dust in the Owens and Mono lakebeds. Pub. L. 
101-549, CAA Amendments of 1990 House Report No. 101-290(l), May 17, 
1990. EPA, however, does not interpret the statutory language in a 
manner that considers any anthropogenic contribution to a natural event 
as transforming it into an anthropogenic event. In the Mono and Owens 
lakebed situation, EPA believed that the anthropogenic contribution was 
such that dust blown from those areas should be treated as 
anthropogenic rather than natural events. In other high winds 
instances, however, where there were anthropogenic contributions with 
adequate controls in place, EPA treated the high wind events as natural 
events.
    In its Natural Events Policy, EPA stated that it would treat a high 
wind event as a natural event even if the dust originated from 
anthropogenic sources, provided best available control measures were in 
place. Memorandum from Mary D. Nichols, Assistant Administrator for Air 
and Radiation to Regional Air Directors, ``Areas Affected by PM-10 
Natural Events,'' May 30, 1996 (NEP) at 7. Congress was cognizant of 
EPA's existing policies on natural and anthropogenic events and how EPA 
interpreted and implemented these policies. In amending section 319, 
Congress specifically required EPA to continue to apply its NEP during 
the exceptional events rulemaking process, an unlikely action if it 
disagreed with EPA's interpretation of natural events. Section 319 
(b)(4)(B). Under the NEP,

[[Page 14692]]

EPA treated high wind events as natural events and reasonably well-
controlled if contributing anthropogenic sources had BACM in place. NEP 
at 7. During the exceptional events rulemaking, EPA sought comment on a 
number of options for mitigation requirements, including whether to 
continue to require BACM for such events. After considering all 
comments on the proposed options, EPA explained in the preamble to the 
final rule that it would continue to require that anthropogenic sources 
contributing to high wind events be well-controlled through reasonable 
and appropriate measures. 72 FR at 13566. EPA, therefore, believes its 
interpretation of a high wind event as set forth in the preamble to the 
EER conforms to congressional intent and the requirements of section 
319.
    Also, in response to Earthjustice's assertion that EPA cites no 
statutory or regulatory authority that permits us to treat high wind as 
a natural event, as discussed above, Congress was aware of EPA's 
interpretation of natural events as evidenced by the statutory 
reference to the NEP (Section 319(b)(4)(B)) and it is self-evident that 
volcanic, seismic, high wind, and other similar events are natural 
events under section 50.1(k) of the EER. Therefore, EPA did not find it 
necessary to specifically list these events as exceptional events in 
the final rule. When asking for comments in the proposed rule, we noted 
that some of these exceptional events (including volcanic, seismic and 
high wind events) have ``unusual characteristics'' and needed a fuller 
discussion in the preamble regarding how states may meet the 
requirements established in the EER. 71 FR at 12605. EPA believed that 
this explanation in the preamble was sufficient to assist states in 
developing their demonstration requirements and did not make it 
necessary to specifically list these events as exceptional events in 
the final rule.
    Comment 6: Earthjustice claims that even if EPA had codified the 
preamble language allowing dust from lands disturbed by human activity 
to be excused, EPA offers no evidence to show whether the sources that 
allegedly were responsible for the dust were reasonably well controlled 
at the time the event occurred. Earthjustice states that EPA must show 
that the sources were actually controlled, not just that they were 
subject to controls. Earthjustice believes that reasonable controls 
would have prevented dust from being entrained by the stated wind 
speeds and that if the winds at issue picked up the large amounts of 
particulate concentrations claimed, then by definition, these sources 
were not reasonably controlled. With respect to September 22, 2006, 
Earthjustice asserts that the fact that the District claims that the 
dust came from anthropogenic sources being scoured by winds under 25 
mph for a short period of time means that reasonable measures could not 
have been in place. Therefore, Earthjustice claims that either the dust 
was not caused by wind or the sources did not have reasonable controls 
that would have prevented the event. With respect to October 25, 2006, 
Earthjustice asserts that none of the 90 inspections conducted by the 
District was in or around the Lemoore/Corcoran area where the dust 
allegedly originated.
    Response 6: With respect to reasonable controls, in the preamble to 
the EER we explained that ``ambient particulate matter concentrations 
due to dust being raised by unusually high winds will be treated as due 
to uncontrollable natural events where * * * the dust originated from 
anthropogenic sources within the State, that are determined to have 
been reasonably well-controlled at the time that the event occurred, or 
from anthropogenic sources outside the State.* * * In cases where 
anthropogenic sources are determined to have contributed to exceedances 
or violations due to high wind events at air quality monitoring sites, 
per our decision in this rulemaking concerning the action that States 
must take to mitigate the impact of exceptional events on public health 
* * * States must take reasonable and appropriate measures to mitigate 
the impact associated with the event on public health.'' 72 FR at 
13576-13577.
    As we observed in our proposed affirmation rule, Regulation VIII 
and District Rule 4550 were in place at the time of the events in 
question. Furthermore, we noted that EPA has approved the District's 
BACM demonstration for all significant sources of PM-10 in the SJV as 
meeting CAA section 189(b)(1)(B). See 72 at 49053 and 49057. Moreover, 
the District conducted numerous inspections of PM-10 sources in the SJV 
on September 22 and October 25, 2006. Thus controls beyond those deemed 
``reasonable'' were being implemented and enforced in the SJV on those 
dates.
    Contrary to Earthjustice's apparent belief, there is nothing in 
either the preamble to the EER or the rule itself that requires EPA to 
show that all sources were ``actually controlled'' at the time of the 
events. Moreover, there are thousands of fugitive dust sources in the 
SJV,\7\ an area of nearly 25,000 square miles which constitutes 
approximately 16 percent of the geographic area of California. 2003 
PM10 Plan for the SJV at 2-1. As a result it would be a practical 
impossibility for the District, a publicly-funded agency, to determine 
whether every source was in compliance with its regulations on any 
given day, the standard Earthjustice evidently espouses. The fact that 
the District conducted 90 inspections on October 25, 2006 and none was 
in Lemoore or Corcoran simply illustrates the magnitude of the task 
Earthjustice suggests should be mandatory for the exclusion of data 
from an exceptional event.
---------------------------------------------------------------------------

    \7\ For example, the District has approved over 6,000 
applications under Rule 4550. ``Conservation Management Practices 
Program Report for 2005,'' January 19, 2006, SJVAPCD at 5.
---------------------------------------------------------------------------

    Finally, Earthjustice presents no support for its contention that 
controls on anthropogenic sources beyond those already in place would 
have prevented dust from being entrained by the stated wind speeds. 
Earthjustice simply asserts (see comment 7) without evidence that there 
are numerous measures available that could have prevented or reduced 
entrainment of particulate matter. As we have shown, reasonable 
controls were in place on the days in question and the exceedances 
occurred notwithstanding those controls. See also our response to 
comment 7 below.
    Comment 7: Earthjustice further asserts that there are numerous 
measures available that could have reduced or prevented the entrainment 
of particulate matter by winds above the entrainment threshold of 18 
mph, many of which are included but not required by the District's 
agricultural CMP rule and Regulation VIII. Earthjustice provides a 
number of examples that it claims are effective in reducing or 
eliminating erosion and transport of soil particles during high wind 
events. Earthjustice concludes that even assuming 100 percent 
compliance with the agricultural CMP rule and Regulation VIII, ``not 
one of these measures is required to be in place by these so-called 
BACM level controls.'' Thus Earthjustice alleges that sources could be 
100 percent in compliance with District rules and still not be doing 
anything to prevent wind-generated entrainment of particulates.
    Response 7: As we stated in the preamble to the EER, where wind 
speed results in particulate matter exceedances, a clear causal 
relationship must be demonstrated between the exceedances measured at 
the air quality monitoring site and the high wind event

[[Page 14693]]

in question in order for data affected by these events to be excluded 
under the weight of evidence approach. 72 FR at 13566, footnote 11. We 
further stated that ``EPA will consider in the weight of evidence 
analysis winds that produce emissions contributed to by anthropogenic 
activities that have been controlled to the extent possible through use 
of all reasonably available reasonable and appropriate measures.'' Id.
    EPA approved Regulation VIII as BACM on February 17, 2006 (71 FR 
8461) and Rule 4550 as BACM on February 14, 2006 (71 FR 7683). The 
control measures in these rules are designed to reduce fugitive dust 
emissions. A number of the measures that sources can choose in 
compliance with the rules are also specifically designed to reduce or 
prevent entrainment of particulate matter during wind events. See, for 
example, in the ``List of Conservation Management Practices,'' May 20, 
2004, for Rule 4550 in the ``Cropland--Other'' category the following 
measures: alternate till, bulk materials control, cover crops, 
permanent crops, surface roughening, wind barrier.
    EPA determines what controls constitute ``all reasonably available 
reasonable and appropriate measures'' on a case by case basis. With 
regard to the SJV, EPA has agreed with the District's finding that ``* 
* * unlike other arid western PM-10 serious nonattainment areas, the 
SJV does not have a regular and repeated windblown dust problem.'' 71 
FR at 7686. In addition, in responding to a comment on its proposed 
approval of the 2003 PM-10 serious area plan for the SJV, EPA observed 
that ``[o]nly five PM-10 exceedance days spanning a 13-year period were 
identified as associated with strong winds.'' 69 FR 30006, 30033 (May 
26, 2004). Under these circumstances, EPA believes that it was not 
necessary for the District's rules to mandate the selection of 
windblown dust measures and that the BACM controls being implemented in 
the SJV constitute ``all reasonably available reasonable and 
appropriate measures.''
    Comment 8: Earthjustice argues that the events at issue cannot be 
claimed as exceptional because the District did not make its 
demonstration according to the procedures outlined in the EER. 
Specifically, Earthjustice states that while EPA relies on 
demonstrations prepared by the District in April and May 2007, the only 
opportunity for public comment provided by the District was on the 
February 2007 version of the analysis. Moreover, Earthjustice states, 
only 15 calendar days were provided for comment on the February version 
and the preamble to EPA's EER provides for a 30-day comment period. 
Earthjustice states that to the extent that EPA believes preamble 
statements to be enforceable, the event cannot be deemed exceptional 
because the District did not meet the procedural requirements in the 
EER. Earthjustice also asserts that since the District's rationale for 
flagging the September 22, 2006 exceedances changed so markedly as to 
make comments on the first draft irrelevant, the documentation should 
have been put out for a second round of public comment. Earthjustice 
further states that insofar as the EER applies to EPA's affirmation 
action, the District also failed to meet its procedural requirements 
that documentation justifying exclusion must be submitted no later than 
12 months before a regulatory decision is made. Here, Earthjustice 
asserts, EPA based its regulatory decision to find the SJV in 
attainment on the exclusion of data before any demonstration supporting 
the exclusion was drafted by the State.
    Response 8: The public did have an adequate opportunity for review 
and comment on the State's documentation of the exceptional events. 
Earthjustice complains that the State did not provide a 30-day comment 
period on the documentation of exceptional events, and further contends 
that there was no opportunity to review and comment after the District 
revised this documentation. EPA's EER provides that a state that has 
flagged data as being due to an exceptional event and that is 
requesting exclusion of the data shall ``after notice and opportunity 
for public comment, submit a demonstration'' to EPA, along with any 
public comments it received. 40 CFR 50.14(c)(3)(i).
    With respect to Earthjustice's first contention regarding the 30-
day comment period, the EER contains no such requirement. The language 
cited by Earthjustice that purports to characterize 30 days as a 
requirement is found in the preamble only, 72 FR 13574, and does not 
reflect the language of the rule. Thus, while indicative of a period 
that EPA would deem reasonable, the preamble language regarding a 30-
day comment period does not serve to make such a period mandatory. Nor 
does it mean that a shorter comment period should be deemed 
unreasonable. Earthjustice concedes that in February 2007 the District 
provided a two week comment period for its initial documentation of the 
September, October and December 2006 exceedances. The District received 
no comments or requests for extension of the comment period.\8\ On 
March 21, 2007, Earthjustice filed with EPA a petition to withdraw 
EPA's October 2006 attainment determination, which cited to and 
discussed the District's initial documentation. This petition, however, 
was directed to EPA and not to the District or the State. Earthjustice, 
having failed to request an extension of the comment period and to 
address comments to the District and the State, cannot now be heard to 
complain about the length of the initial comment period.
---------------------------------------------------------------------------

    \8\ Contrary to Earthjustice's contention (EC at 3, footnote 3), 
EPA in its proposal did nothing to ``hide'' the date that the 
documentation became available. EPA simply stated that the 
documentation became available in February.
---------------------------------------------------------------------------

    Subsequently, the District posted on the ``Public Notices'' section 
of its Web site revised versions of the documentation for exceedances 
on these three days at issue, and thus the revised documentation was 
also available for public review and comment. These revised versions 
modified and clarified the technical analysis of the high wind events. 
For the September 22 event, the District posted on its Web site a 
revised set of documentation, dated April 20, and CARB subsequently 
submitted it to EPA. The District submitted an Addendum to CARB on May 
23, 2007, which it again posted on its Web site, and CARB later 
submitted it to EPA. 72 FR at 49050. For the October 25 event, the 
District posted on its Web site a revised set of documentation, dated 
April 23, and CARB again subsequently submitted it to EPA. 72 FR at 
49054. For the December 8, 2006 event, which Earthjustice does not 
contest is an exceptional event, the District revised its documentation 
and submitted it to CARB on May 23, 2007, and posted it on its Web 
site. At CARB's request the District made further revisions which it 
submitted to CARB on June 6, 2007, and posted on its Web site. 72 FR at 
49057. The State later submitted it to EPA. Id.
    Thus each set of revised documentation was available to the public 
in the ``Public Notices'' section of the District's Web site for months 
prior to EPA's August 15, 2007 issuance of its proposed rule, and EPA 
has found no indication that comments were submitted or inquiries 
received about the revised documentation. EPA therefore believes that 
there was adequate opportunity for the public to comment on the revised 
demonstrations made by the District and CARB. The fact remains that no 
comments were submitted to the District or CARB on the original 
versions of the documentation, nor does it appear that there were any 
requests for an extension of the comment period that closed on March 5,

[[Page 14694]]

2007. Similarly, EPA knows of no comments or requests regarding the 
comment period that were submitted on the subsequent versions of the 
documentation that were posted on the District's Web site.
    Earthjustice further contends that EPA has failed to meet the 
requirement that a demonstration be submitted to EPA no later than 12 
months ``prior to the date'' a regulatory decision ``must'' be made by 
EPA. EER, section 50.14(c)(3)(i). We note initially that this section 
of the EER is designed for EPA's benefit, to furnish adequate time to 
review documentation, and it is thus for EPA to determine whether we 
require the full time allotted by the rule.
    Furthermore, in the preamble we ``recognize that special 
circumstances could dictate more expedited data delivery, flagging, and 
minimal demonstrations * * *.'' 72 FR at 13571. In this case, where EPA 
is acting to affirm a prior attainment determination that recognized 
the need for additional evaluation of preliminary data, EPA finds there 
is value in proceeding expeditiously to obtain and review the State's 
documentation of those data and surrounding exceptional events. 
Moreover, this action to affirm EPA's attainment determination is not a 
regulatory decision that ``must'' be made by a certain date, and 
therefore the 12-month requirement is not applicable. Finally we note 
that the bulk of the revised documentation for the September and 
October 2006 exceedances at issue here was submitted to EPA in April 
and May 2007, well in advance of EPA's final regulatory decision in 
this rulemaking. Thus EPA finds that, for all the reasons set forth 
above, the timing of submission of the documentation here was adequate 
for purposes of section 50.14(c)(3)(i) of the EER.
    Earthjustice also complains that in issuing the October 2006 
determination of attainment, EPA made the determination to finally 
concur in the flagging of exceptional events prior to receiving the 
State's documentation. The procedural validity of the October 2006 
determination, and whether it provided adequate notice and comment, is 
not at issue in today's rulemaking. Thus Earthjustice's contentions 
with regard to notice and comment issues arising from the October 2006 
rulemaking are misplaced here.
    Moreover, Earthjustice's contentions are belied by the facts. EPA's 
October 2006 determination of attainment made clear that the data 
showing exceedances on September 22, 2006 were preliminary. EPA stated 
that once quality-assured data were available, EPA would review those 
data and CARB's request with respect to them, evaluate whether the data 
qualified for exclusion as caused by exceptional events, and determine 
whether the determination should be withdrawn.\9\ See discussion in 
EPA's proposed affirmation rule, 72 FR at 49064. See also 71 FR 63642.
---------------------------------------------------------------------------

    \9\ As EPA noted in its proposed affirmation rule, EPA's 
October, 2006 final determination did not ignore the exceedances 
that occurred in October 2006 since these occurred eight days after 
EPA promulgated its final determination of attainment. 72 FR at 
49064.
---------------------------------------------------------------------------

    In today's rulemaking EPA has fulfilled its promise by providing 
ample opportunity for comment on the State's documentation and EPA's 
evaluation of exceedances under the EER prior to issuing a final 
concurrence. As EPA noted in its proposed affirmation rule, our purpose 
here is not to take comment on the issues raised by the 2006 attainment 
determination, except to the extent that they affect EPA's ability to 
determine that the SJV continued to attain the PM-10 standard through 
2006. 72 FR at 49047. The October 2006 rulemaking, which is not at 
issue in this current action, did not purport to be a final concurrence 
on the State's exceptional events documentation for the September 22, 
exceedances. Today's rulemaking addresses quality-assured data for 
September, October and December 2006, for which the State has provided 
exceptional events documentation.
    Comment 9: Earthjustice states that EPA argues that at the time of 
the attainment finding the Agency merely deferred its determination of 
the impact of the preliminary data until they could be quality assured 
and the State had an opportunity to show that the exceedance was caused 
by an exceptional event. Earthjustice claims that the data at issue had 
in fact been processed by the CARB laboratory and thus already quality 
assured by the State when EPA was notified of the September 22, 2006 
exceedances. In this respect, Earthjustice believes that EPA 
mischaracterized CARB's October 17, 2006 letter to EPA to mean that the 
data from the filter analyses were preliminary. Thus, Earthjustice 
concludes that EPA's decision not to consider the September 22 
exceedances in its October 17, 2006 attainment finding is a violation 
of law and an abuse of discretion. Earthjustice also states that this 
violation of the Administrative Procedure Act (APA) cannot be cured 
with this rulemaking's post-hoc rationalization. Earthjustice 
interprets 40 CFR 51.14(c)(2)(ii) to mean that an exceedance must be 
considered an exceedance unless and until EPA gives final concurrence 
following a thorough, convincing, publicly reviewed demonstration that 
the data can be ignored.
    Response 9: As noted in the response to comment 8 above, the 
adequacy and validity of the October 2006 rulemaking is not at issue in 
this proceeding. Whether the APA was violated in that rulemaking is not 
at issue here. In this current rulemaking, EPA thoroughly reviewed and 
proposed to concur with the documentation submitted by the State, and 
provided full opportunity for public review and comment before 
finalizing its concurrence with the flags, and before excluding the 
data from a final determination of attainment. The purpose of this 
rulemaking is to assess the quality-assured data and documentation of 
exceptional events claims in the context of notice and comment 
rulemaking. Thus, even if, for the sake of argument, we accept 
Earthjustice's contentions that there were procedural deficiencies in 
the October 2006 rulemaking, EPA would have cured any such deficiencies 
with the procedures it has followed in this rulemaking.
    In any event, Earthjustice is incorrect in its assertions that, at 
the time of the October 2006 rulemaking, data for September 22, 2006 
were not preliminary and had been quality assured. The data for the 
September 22 exceedances were plainly preliminary. An EPA staff 
employee e-mailed a CARB branch chief an informal request to ``find out 
if there was any preliminary data available from the ARB lab.'' E-mail 
from Bob Pallarino, EPA, to Karen Magliano, Chief, Air Quality Data 
Branch, Planning and Technical Support Division, CARB, October 12, 
2006. On October 13, 2006 she forwarded to EPA an informal e-mail 
originating from a CARB staffer. The e-mail included data from filter 
analyses of several monitors, which set forth numerical values 
representing monitored data. That e-mail stated clearly: ``Of course, 
all the data is preliminary.'' E-mail from Scott Randall, Inorganic 
Laboratory Section, Northern Laboratory Branch, CARB, to Cliff Popejoy, 
Inorganic Laboratory Section, Northern Laboratory Branch, CARB, October 
13, 2006 (forwarded to Bob Pallarino by Karen Magliano). Thus, CARB 
represented and EPA reasonably believed that the data showing monitored 
exceedances were ``preliminary'' and not quality assured. Indeed, EPA 
believed that the normal data validation and verification processes had 
not been undertaken, and that, in fact, the data had not been

[[Page 14695]]

submitted to EPA's Air Quality System (AQS) database \10\ or certified 
by CARB. The message that the CARB staffer sent was in response to an 
informal request from EPA staff, and in that context EPA did not 
consider it an official CARB submission of data. The informal and 
preliminary nature of the information is further indicated by the fact 
that the numerical values for PM-10 reported in the e-mail were not 
accompanied by scientific units, which would be essential documentation 
in any official submission of quality-assured data, and could only be 
inferred by EPA based on usual practice.
---------------------------------------------------------------------------

    \10\ Data from air monitors operated by state and local agencies 
in compliance with EPA monitoring requirements must be submitted to 
AQS. Heads of monitoring agencies annually certify that these data 
are accurate to the best of their knowledge. See 71 FR at 40953.
---------------------------------------------------------------------------

    EPA did not therefore, as Earthjustice contends, 
``mischaracterize'' the data from the filter analyses, when it 
described the data as ``preliminary.'' EC at 11, footnote 9. CARB 
itself characterized the data as preliminary when it forwarded them to 
EPA.
    In any event, as noted above, what is at issue in this rulemaking 
is EPA's concurrence on the exceptional events documentation for 
quality-assured data subsequent to EPA's October 2006 determination, 
and not the procedural validity of that prior determination. It is 
clear in this rulemaking that EPA is determining to finally concur on 
the State's flagging of the data only after EPA has conducted notice 
and comment rulemaking on documentation that the State has submitted to 
support those flags.
    Comment 10: For the wind events, Earthjustice maintains that the 
data offered by the District and relied upon by EPA does not 
demonstrate a ``clear causal relationship'' because exceedances were 
being measured before the events occurred.
    Response 10: EPA disagrees with Earthjustice's conclusion for the 
reasons discussed below. Initially it is important to understand that 
the 24-hour PM-10 NAAQS, 150 [mu]g/m\3\, is a 24-hour average 
concentration. This means that individual hourly concentrations at any 
given monitoring location may exceed 150 [mu]g/m\3\, but until all 24 
hours of a day are sampled a complete daily reading cannot be 
calculated. Therefore it is incorrect to characterize the data, as 
Earthjustice does, as showing that NAAQS exceedances were measured 
before the wind events.
    To support its contention, Earthjustice states that fugitive dust 
sources in the Lemoore area on September 22 and October 25, 2006 could 
not have caused the Corcoran NAAQS exceedances since the first hourly 
PM-10 concentrations exceeding 150 [mu]g/m\3\ at Corcoran occurred 
either an hour before or at the same time as the Lemoore meteorological 
station recorded wind speeds exceeding the District's threshold wind 
speed. From these facts, Earthjustice concludes that since the monitor 
was already recording an hourly concentration above the NAAQS before 
the dust-laden winds from Lemoore \11\ arrived on September 22 and 
October 25, the monitor could not have been impacted by them.
---------------------------------------------------------------------------

    \11\ Throughout this final rule when we refer to Lemoore, 
Corcoran and Bakersfield, we mean the Lemoore area, the Corcoran 
area, and the Bakersfield area. When analyzing data, the State, 
District and EPA use information collected from specific points 
where the monitors are located, whether meteorological monitors or 
PM-10 monitors. Since it is not possible, due to finite resources, 
to monitor pollutant or meteorological parameters in every location, 
monitoring locations are chosen to be representative of larger 
areas. The size of the area represented by a monitor is dependent on 
a number of factors, including, but not limited to, the parameter 
being measured (e.g., wind speed, PM-10 concentration), the overall 
terrain (e.g., urban, rural, valley, etc.) and any localized 
characteristics that may influence the parameter being measured 
(e.g., obstructions such as buildings or trees).
---------------------------------------------------------------------------

    In evaluating this conclusion it is instructive to look at any 
number of days where the level of an hourly PM-10 concentration at 
Corcoran exceeded the level of the 24-hour NAAQS, yet the 24-hour 
average concentration for the day did not exceed the NAAQS. October 26 
and 27, 2006, March 26 and 27, 2007, April 17, 2007, May 2 and 21, 
2007, and June 5, 2007, all experienced one or more hours exceeding the 
level of the NAAQS yet the NAAQS for the day was not exceeded. See 
Table 1 below. The most extreme example is April 17, 2007, on which 
four continuous hourly concentrations greater than 150 [mu]g/m\3\ were 
recorded from 4:00 p.m. Pacific Standard Time (PST) through 7 p.m. PST 
(181, 466, 460, 236 [mu]g/m\3\, respectively), yet the overall 24-hour 
average concentration for that day was only 91 [mu]g/m\3\.

                 Table 1.--Non-Exceedance Days With One or More Hourly Pm-10 Concentrations Above 150 [mu]g/m\3\ as Measured at Corcoran
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Oct 26     Oct 27     Mar 26     Mar 27     Apr 17     May 2      May 21     Jun 5
                                                                     2006       2006       2007       2007       2007       2007       2007       2007
                              Hour*                                ([mu]g/    ([mu]g/    ([mu]g/    ([mu]g/    ([mu]g/    ([mu]g/    ([mu]g/    ([mu]g/
                                                                    m\3\)      m\3\)      m\3\)      m\3\)      m\3\)      m\3\)      m\3\)      m\3\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
0...............................................................        157         79          8          0         27         18         17         21
1...............................................................        143        135         11          0         26         14         16         15
2...............................................................        146        126          8          1         30         13         15         12
3...............................................................        147         89         11          3         31         11         13         13
4...............................................................        161         69          9          3         29         12         15         24
5...............................................................        175         91         10          3         63         26         16         24
6...............................................................        194        221         22          5         73         23         25         22
7...............................................................        232        184         19          7         34         25         28         19
8...............................................................        115        158         16          0         34         20         35         14
9...............................................................         66        149         12          8         33         13         42         18
10..............................................................         53        107          2          1         22         16         59         23
11..............................................................         92        117          6         18         21         16         66         35
12..............................................................        128         86          8        122         15         20         72         61
13..............................................................        128         70         17        162         26         22         74         87
14..............................................................        133         91          7        152         54         25         85         77
15..............................................................        115         69          7        190        138         28         84        254
16..............................................................        126         87         18         54        181        151         94        169
17..............................................................        152        116         19         86        466        239        195        145
18..............................................................        151        140        128         47        460         61        180        173
19..............................................................        145        116        407          8        236         27        127        235
20..............................................................        161        126         48         17        136         13        108         65

[[Page 14696]]

 
21..............................................................        147        118         16         15         34         14         66         34
22..............................................................        124        141          4          9         14         29         61         27
23..............................................................        130        105          0         10          7         16         66         49
                                                                 ---------------------------------------------------------------------------------------
Daily Average...................................................        137        116         34         38         91         36         65         67
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: EPA Air Quality System Database.
* Hours are in PST. All State and local ambient air pollutant monitoring equipment in California operates on PST all year and is never adjusted for
  Daylight Savings Time. For example, hour 12 in the table is 1 p.m. Pacific Daylight Time (PDT).

    Thus, as can be seen from Table 1 and the discussion above, 
Earthjustice is incorrect when it concludes that dust-laden winds from 
Lemoore could not have affected the Corcoran monitor on September 22 
and October 25, 2006 because concentrations above the level of the 
NAAQS were recorded at the monitor before the winds arrived. By failing 
to account for all 24 hours of the day, Earthjustice has misinterpreted 
how EPA determines compliance with the 24-hour PM-10 NAAQS.
    Earthjustice further states that fugitive dust sources in the 
Lemoore area on September 22 and October 25, 2006 could not have caused 
the Corcoran NAAQS exceedances since the first hourly PM-10 
concentrations exceeding the level of the NAAQS at Corcoran occurred 
either an hour before or at the same time as the Lemoore meteorological 
station recorded wind speeds exceeding the 18 mph threshold speed.\12\ 
Earthjustice notes that on September 22 the 6:00 a.m. hourly PM-10 
concentration at Corcoran exceeded the level of the NAAQS and wind 
speeds recorded in Lemoore did not exceed the threshold wind speed 
until 7 a.m. On October 25 the Corcoran hourly PM-10 concentration 
first exceeded the level of the NAAQS at 6 a.m., the same time the 
Lemoore meteorological station recorded winds in excess of the 
threshold speed.\13\ However, as set forth below, the data show that on 
September 22 the winds at Lemoore began exceeding the threshold speed 
at 6 a.m. PST, and likely began affecting the concentrations at the 
Corcoran monitor by the time concentrations were recorded at 7 a.m. 
PST.\14\ On October 25, the winds recorded at Lemoore exceeded the 
threshold speed at 5 a.m. PST and likely affected the concentrations 
recorded at the Corcoran monitor beginning at 6 a.m. PST. Thus on both 
days there was at most a period of one or two hours where the 
concentrations at the monitor that exceeded the standard might not have 
been attributable to the winds from Lemoore.
---------------------------------------------------------------------------

    \12\ The State cites a 2002 California Regional PM-10/PM-2.5 Air 
Quality Study (2002 CRPAQS Study) that established a dust-generating 
wind speed threshold of 17.8 mph to support its conclusion that 
these wind speeds were sufficient to erode soils and entrain dust 
into the atmosphere as well as to exacerbate the entrainment of dust 
from the anthropogenic activities. See our proposal at 72 FR at 
49052.
    \13\ As will be discussed further below, EPA uncovered an error 
in the reporting of the meteorological data from Lemoore. The data 
for Lemoore winds were reported in the State's documentation in PDT 
as opposed to the other meteorological and PM-10 concentration data 
which were reported in PST. This means that the wind speeds 
increased an hour earlier than had previously been reported in the 
State's documentation. Therefore when Earthjustice refers to wind 
data from Lemoore at 6 a.m. and 7 a.m., the actual times were 5 a.m. 
and 6 a.m. PST.
    \14\ Hourly concentrations recorded by PM-10 continuous monitors 
are reported in the beginning hour. That is, an hourly average 
concentration calculated from readings taken between the hours of 7 
a.m. and 8 a.m. would be reported as the average hourly 
concentration for 7 a.m.
---------------------------------------------------------------------------

    Nevertheless, based upon meteorological data, EPA believes that the 
high concentrations measured beginning at 7 a.m. PST on September 22 
and 6 a.m. on October 25 and continuing throughout the day were due to 
transport of dust by high winds in the Lemoore area, and thus resulted 
in the exceedance of the 24-hour NAAQS. In reaching this conclusion, 
EPA evaluated the available hourly concentration data from the Corcoran 
monitoring site \15\ from October 1, 2006 through June 30, 2007 to 
determine how often the Corcoran site recorded high hourly 
concentrations in the morning. While high morning concentrations were 
relatively rare in the data we evaluated, when they do occur they do 
not always result in a 24-hour average concentration that exceeds the 
NAAQS. Table 2 below compares days with high morning concentrations, 
October 26 and 27, 2006, that did not exceed the 24-hour NAAQS with 
September 22 and October 25, 2006, days with high morning 
concentrations that ultimately did exceed the 24-hour NAAQS.
---------------------------------------------------------------------------

    \15\ In October 2006, the SJVAPCD began the routine submittal of 
continuous PM-10 data to EPA's AQS database. These data are recorded 
with a special purpose Federal Equivalent Method (FEM) monitor and 
the District began submitting these data in response to new 
requirements contained in EPA's revised monitoring regulations (71 
FR 61236, October 17, 2006). Prior to this regulation revision, air 
monitoring agencies were not required to submit special purpose 
monitoring data to the AQS database. Therefore, the amount of 
certified pollutant data available for our analysis is limited to 
October 1, 2006 through September 30, 2007.

      Table 2.--Corcoran Hourly Concentrations on September 22, October 25, October 26 and October 27, 2006
----------------------------------------------------------------------------------------------------------------
                                                   September 22,    October 25,     October 26,     October 27,
              Hour (standard time)                 2006  (conc.    2006  (conc.    2006  (conc.    2006  (conc.
                                                    [mu]g/m\3\)     [mu]g/m\3\)     [mu]g/m\3\)     [mu]g/m\3\)
----------------------------------------------------------------------------------------------------------------
0...............................................              63              84             157              79
1...............................................              39              57             143             135
2...............................................              51              38             146             126
3...............................................              64              42             147              89
4...............................................              55              30             161              69
5...............................................              78              39             175              91

[[Page 14697]]

 
6...............................................             170             269             194             221
7...............................................             306             346             232             184
8...............................................             519             651             115             158
9...............................................             531             674              66             149
10..............................................             725             777              53             107
11..............................................             695             794              92             117
12..............................................             521             681             128              86
13..............................................             318             580             128              70
14..............................................             276             510             133              91
15..............................................             247             302             115              69
16..............................................             269             179             126              87
17..............................................             283             184             152             116
18..............................................             258             180             151             140
19..............................................             223             178             145             116
20..............................................             150             166             161             126
21..............................................             144             201             147             118
22..............................................             138             183             124             141
23..............................................             144             150             130             105
                                                 ---------------------------------------------------------------
    Daily average...............................             261             304             137            116
----------------------------------------------------------------------------------------------------------------
Source: EPA Air Quality System Database, ``Natural Event Documentation, Corcoran, Oildale and Bakersfield,
  California, September 22, 2006'' San Joaquin Valley Unified Air Pollution Control District, April 20, 2007 and
  ``Natural Event Documentation, Corcoran and Bakersfield, California, October 25, 2006,'' San Joaquin Valley
  Unified Air Pollution Control District, April 23, 2007.

    As can be seen from Table 2, early morning hourly concentrations on 
October 26 and 27, 2006 were comparable to morning hourly values on 
September 22 and October 25, 2006. All of these days recorded high 
early morning hourly values. However, the hourly concentrations on 
September 22 and October 25, 2006 continue to increase throughout the 
morning and into the afternoon and evening while the hourly 
concentrations for October 26 and 27 begin to decrease after hour 7 and 
then later increase slightly in the afternoon and evening. As discussed 
above, we believe the increasing concentrations for the morning and 
afternoon for September 22 and October 25 are associated with an 
increase in hourly wind speeds, as measured in Lemoore. Even if we 
assume that several of the hours of high early morning concentrations 
at Corcoran on September 22 and October 25 were caused by something 
other than windblown dust, we have shown that there would not have been 
an exceedance of the 24-hour NAAQS that day without the subsequent high 
hourly concentrations that were caused by windblown dust transported 
from the Lemoore area.
    Moreover, an evaluation of meteorology in the Lemoore area on 
October 26 and 27, 2007 shows that the wind conditions on September 22 
and October 25, 2006 were much different from October 26 and 27, days 
that had high morning concentrations but ultimately did not exceed the 
24-hour NAAQS. Table 3 below summarizes this information.

       Table 3.--Corcoran Hourly PM-10 Concentrations and Lemoore Hourly Wind Speeds for September 22, October 25, October 26 and October 27, 2006
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   September 22, 2006     October 25, 2006      October 26, 2006      October 27, 2006
                                                                 ---------------------------------------------------------------------------------------
                              Hour                                  Conc.     Lemoore     Conc.     Lemoore     Conc.     Lemoore     Conc.     Lemoore
                                                                   ([mu]g/   windspeed   ([mu]g/   windspeed   ([mu]g/   windspeed   ([mu]g/   windspeed
                                                                    m\3\)      (mph)      m\3\)      (mph)      m\3\)      (mph)      m\3\)      (mph)
--------------------------------------------------------------------------------------------------------------------------------------------------------
0...............................................................         63         12         84         10        157          3         79          7
1...............................................................         39          9         57         10        143          0        135          6
2...............................................................         51         10         38         10        146          7        126          7
3...............................................................         64          8         42         17        147          7         89          6
4...............................................................         55         10         30         16        161          8         69          6
5...............................................................         78          8         39         22        175          9         91          7
6...............................................................        170         21        269         22        194          3        221          6
7...............................................................        306         21        346         22        232          0        184          3
8...............................................................        519         28        651         26        115          0        158          0
9...............................................................        531         29        674         29         66          0        149          3
10..............................................................        725         23        777         31         53          5        107          6
11..............................................................        695         17        794         30         92          3        117          5
12..............................................................        521         17        681         28        128          0         86          3
13..............................................................        318         21        580         26        128          0         70          5
14..............................................................        276         14        510         22        133          0         91          6
15..............................................................        247          5        302         20        115          0         69          7
16..............................................................        269         10        179         14        126          5         87          7

[[Page 14698]]

 
17..............................................................        283          9        184          3        152          3        116          5
18..............................................................        258          6        180          6        151          5        140          6
19..............................................................        223          8        178          8        145          7        116  .........
20..............................................................        150          7        166          9        161          6        126          8
21..............................................................        144          9        201          8        147          8        118          0
22..............................................................        138          0        183          8        124          8        141          3
23..............................................................        144          7        150  .........        130          6        105          8
                                                                 ---------------------------------------------------------------------------------------
    Daily Average...............................................        261  .........        304  .........        137  .........        116  .........
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: EPA AQS Database, Mesowest historical meteorological data, Mesowest, http://www.met.utah.edu/mesowest/.

    From this tabulation we can see that while hourly concentrations 
measured at Corcoran exceeded the level of the NAAQS during the morning 
hours on all four days, it was only on September 22 and October 25, 
2006 that sustained high winds in the central SJV, represented by data 
from the Lemoore area, generated enough fugitive dust to cause an 
increase in the hourly concentrations in Corcoran recorded at and after 
7 a.m. PST on September 22 and at and after 6 a.m. PST on October 25. 
These increases in hourly concentrations throughout the morning hours 
were a result of the high winds that occurred in the Lemoore area. 
Therefore it is incorrect to conclude, as Earthjustice does, that the 
State cannot show a causal connection between the winds and the 24-hour 
PM-10 exceedances at Corcoran on September 22, 2006 simply because the 
monitor recorded an hourly concentration above the level of the NAAQS 
at the same time winds in the Lemoore area began to exceed the 
threshold wind speed. Further, contrary to Earthjustice's contention, 
the winds at Lemoore on October 25, 2006 exceeded the threshold for 
entrainment prior to the time that increased concentrations were 
recorded at Corcoran and likely affected those concentrations.
    Finally, the timing of the wind speeds shows an increase an hour 
earlier than was previously reported, and thus a corresponding earlier 
impact on the monitor. In evaluating the State's documentation we 
uncovered an error in how the meteorological data from the Lemoore 
meteorological station was reported. In both its April 20, 2007 
``Natural Event Documentation, Corcoran, Oildale and Bakersfield, 
September 22, 2006,'' and its April 23, 2007 ``Natural Event 
Documentation, Corcoran and Bakersfield, October 25, 2006,'' the 
District reported the Lemoore meteorological data in PDT as opposed to 
PST. This was confirmed when EPA independently obtained data for the 
Lemoore meteorological monitoring station. As noted previously in Table 
1, all State and local ambient air pollutant monitoring equipment in 
California operates on PST year round and is never adjusted for 
Daylight Savings Time. Therefore, the information presented in Table 3 
of the State's April 20, 2007 documentation and Table 1 of the State's 
April 23, 2007 documentation incorrectly lists the time when winds in 
Lemoore reached the threshold wind speeds.
    As can be seen in Table 3 above and Tables 4 and 5 below, which 
reflect the proper times for reported wind speeds, on September 22, 
2006 winds at Lemoore reached 21 mph, exceeding the threshold wind 
speed, at 6 a.m. PST, which would be 7 a.m. PDT. On October 25, 2006 
winds at Lemoore reached 22 mph at 5 a.m. PST, which would be 6 a.m. 
PDT. This adjustment strengthens the State's demonstration by showing 
that the winds in Lemoore affected the PM-10 concentrations at Corcoran 
and Bakersfield an hour earlier than originally reported in the 
documentation.
    Comment 11: Earthjustice asserts that the one run of the model that 
EPA relies on demonstrates that there is no connection between the 
events in and around Lemoore and the exceedances measured in 
Bakersfield and Oildale.
    Response 11: The model to which Earthjustice refers is the Hybrid 
Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT). 
However, contrary to Earthjustice's assertion, EPA did not rely on the 
State's HYSPLIT analysis to make its decision to concur with the 
State's demonstration of causal connection. Rather, in its proposal, 
EPA noted the limitations of the HYSPLIT model, describing it merely as 
offering some support to the State's demonstration that winds were of 
the appropriate intensity and direction to move a plume of dust from 
the central SJV to the Bakersfield area.\16\ See 72 FR at 49052. EPA is 
concurring with the State's causal connection demonstration based on 
actual meteorological data recorded on September 22 and October 25, 
2006 which show winds of the appropriate intensity and direction 
occurring at the appropriate times.
---------------------------------------------------------------------------

    \16\ The Oildale monitoring site does not record hourly PM-10 
concentrations but uses a manual PM-10 sampler that provides only 
24-hour average concentrations. The Bakersfield-Golden State Highway 
monitoring site utilizes both a manual sampler for average 24-hour 
PM-10 concentrations and a continuous PM-10 analyzer to provide 
hourly concentrations. Since the Bakersfield-Golden State Highway 
site and the Oildale site are relatively close to each other (3.5 
miles apart), we believe it is appropriate to use the Bakersfield-
Golden State Highway continuous analyzer to characterize the 
temporal distribution of hourly concentrations at both sites.
---------------------------------------------------------------------------

    The State's demonstration included actual meteorological data that 
showed that there were wind speeds between Corcoran and Bakersfield 
that exceeded the threshold wind velocities. For example, the State's 
demonstration for September 22 included meteorological data from a 
monitoring station in Alpaugh (15 miles SSE of Corcoran) which showed 
winds in excess of the 18 mph threshold at 9:00 am PST and in the 15-16 
mph range until 12 pm PST. Wind gusts at Bakersfield Meadow Field 
Airport also approached the threshold wind speed, with a gust speed of 
17 mph recorded at 12:30 p.m. PST. The hourly concentrations in the 
Bakersfield area began to exceed the level of the PM-10 NAAQS at noon 
and stayed above 200 [mu]g/m\3\ for the remainder of the day. We 
discussed the transport of dust from the Lemoore and Corcoran

[[Page 14699]]

areas in our proposal at 72 FR at 49052 for September 22 and at 49055-
49056 for October 25. As we indicated, the winds between Lemoore and 
Corcoran and Corcoran and Bakersfield were sufficient to keep entrained 
dust suspended so that it could be transported.
    As part of our review of the State's documentation we researched 
whether any other publicly available meteorological data supported the 
State's demonstration and found that wind data collected at Allensworth 
State Park (20 miles SE of Corcoran) also recorded wind speeds on 
September 22, 2006 in excess of the 18 mph. While most of the wind 
speeds recorded in Alpaugh and Allensworth State Park in the late 
morning and afternoon hours did not exceed the threshold wind speed, we 
believe these wind speeds were sufficient to transport suspended PM-10 
from the Corcoran area to the Bakersfield area. See our proposed rule 
at 72 FR at 49052. The wind direction from all of the sites on 
September 22 is consistent with the south, southeast transport of dust 
(i.e., winds from the north and northwest) from the Lemoore area to 
Corcoran and the Bakersfield area as demonstrated by Table 4 below.

 Table 4.--September 22, 2006 Daytime Hourly Windspeeds and Concentration Data for the Central and Southern SJV
----------------------------------------------------------------------------------------------------------------
                                                                                                    Bakersfield
      Hour        Lemoore  WS/WD/gusts  Corcoran conc.     Alpaugh WS*/WD     Allensworth State   conc.  ([mu]g/
                                          ([mu]g/m\3\)                           Park  WS/WD           m\3\)
----------------------------------------------------------------------------------------------------------------
6...............  21/NW...............             170  5.5/W..............  3/WSW..............              74
7...............  21/NW...............             306  3.3/WSW............  6/NNE..............             104
8...............  28/NNW/35...........             519  9.7/NNW............  20/NNW.............              78
9...............  29/NNW/37...........             531  19.1/NNW...........  35.................             114
10..............  23/NW/30............             725  15.2/NNW...........  15/NW..............             103
11..............  17/NNW/24...........             695  15.5/NNW...........  8/NW...............             139
12..............  17/NNW/25...........             521  16.1/NW............  ND.................             168
13..............  21/NNW..............             318  13.6/NW............  2/3................             196
14..............  14/NNE..............             276  12.1/NW............  7/NW...............             239
15..............  5/N.................             247  12.1/NW............  8/WNW..............             294
16..............  10/N................             269  10.2/NW............  7/NNW..............             285
17..............  9/NNW...............             283  9.7/NNW............  5/NNW..............             281
18..............  6/N.................             258  5.5/NNW............  1/WSW..............            270
----------------------------------------------------------------------------------------------------------------
ND--No Data.
Source: ``Natural Event Documentation, Corcoran, Oildale and Bakersfield, California, September 22, 2006,'' San
  Joaquin Valley Unified Air Pollution Control District, April 20, 2007; ``Addendum, Natural Event
  Documentation, Corcoran, Oildale and Bakersfield, California, September 22, 2006,'' San Joaquin Valley Unified
  Air Pollution Control District, May 23, 2007; Mesowest historical meteorological data, Mesowest, http://www.met.utah.edu/mesowest/.
* Wind Speed data at Alpaugh adjusted to 10 meter AGL based on conversion formula in the ``Addendum, Natural
  Event Documentation, Corcoran, Oildale and Bakersfield, California, September 22, 2006,'' San Joaquin Valley
  Unified Air Pollution Control District, May 23, 2007 at 13.

    For October 25, the State included all available meteorological 
data in its documentation.\17\ These data support the demonstration 
that winds between the Corcoran and Bakersfield areas were sufficient 
to transport dust on October 25. We believe that the wind speed and 
direction data collected at Alpaugh and Bakersfield Meadow airport, 
while not exceeding the threshold wind speed, show that the winds in 
this portion of the SJV on October 25 were sufficient to transport 
suspended PM-10 from the Corcoran area to the Bakersfield area. See our 
proposed rule at 72 FR at 49052. The wind direction from all of the 
sites during the daytime hours on October 25 is consistent with the 
south, southeast transport of dust (i.e., winds from the north and 
northwest) from the Lemoore area to Corcoran and the Bakersfield area 
as demonstrated by Table 5 below.
---------------------------------------------------------------------------

    \17\ See ``Natural Event Documentation, Corcoran and 
Bakersfield, California, October 25, 2006,'' April 23, 2007 at 44-
74.

   Table 5.--Hourly Daytime Windspeeds and Concentration Data for Central and Southern SJV on October 25, 2006
----------------------------------------------------------------------------------------------------------------
                                        Corcoran conc.                          Bkrsfld Meadow     Bkrsfld conc.
      Hour        Lemoore  WS/WD/gusts    ([mu]g/m\3\)     Alpaugh WS*/WD       Airport WS/WD      ([mu]g/m\3\)
----------------------------------------------------------------------------------------------------------------
6...............  22/NNW/30...........             269  3.5/SSW............  5/ESE..............              97
7...............  22/NNW/32...........             346  2.9/W..............  6/E................              89
8...............  26/NW/36............             651  5.6/NW.............  0..................              88
9...............  29/NNW/39...........             674  17.0/NNW...........  10/NW..............             123
10..............  31/NW/37............             777  16.5/NNW...........  9/WNW..............             148
11..............  30/NW/40............             794  16.8/NNW...........  12/W...............             177
12..............  28/NNW/38...........             681  15.6/NNW...........  12/WNW.............             195
13..............  26/NNW/35...........             580  14.8/NNW...........  6/ND...............             222
14..............  22/NNW/31...........             510  13.2/NNW...........  7/ND...............             415
15..............  20/NW /26...........             302  13.3/NNW...........  7/NW...............             406
16..............  14/NNW..............             179  12.7/NNW...........  3/WNW..............             393
17..............  3/N.................             184  6.5/NW.............  5/NW...............             416

[[Page 14700]]

 
18..............  6/N.................             180  4.4/WNW............  3/NW...............            403
----------------------------------------------------------------------------------------------------------------
ND--No data available.
Source: ``Natural Event Documentation, Corcoran and Bakersfield, California, October 25, 2006,'' San Joaquin
  Valley Unified Air Pollution Control District, April 23, 2007; Mesowest historical meteorological data,
  Mesowest, http://www.met.utah.edu/mesowest/.
* Wind Speed data at Alpaugh adjusted to 10 meter above ground level (AGL) based on the conversion formula in
  ``Natural Event Documentation, Corcoran, Oildale and Bakersfield, California, October 25, 2006,'' San Joaquin
  Valley Unified Air Pollution Control District, April 23, 2007 at 25.

    In its documentation the State also included the results of a 
HYSPLIT model run by the District to identify source regions for the 
parcels of air that impacted the Corcoran and Bakersfield monitors on 
September 22 and October 25, 2006. The District explicitly stated that 
the models were not intended to quantify particulate concentrations but 
simply were used to support its view of the origin of the particulate 
matter that impacted the monitors at Corcoran and Bakersfield. As 
stated in the proposed rule, EPA agrees that this model run supports 
the conclusions drawn from the meteorological data presented. See 72 FR 
at 49052 and 49056.
    In its comment letter on the proposed affirmation rule, 
Earthjustice relies on its own computer simulations using the HYSPLIT 
model and appears to claim that, based on its own HYSPLIT analyses, the 
winds in the Lemoore area could not have carried sufficient quantities 
of particulate matter to Bakersfield to cause exceedances of the PM-10 
NAAQS. In order to evaluate Earthjustice's HYSPLIT analyses, EPA also 
performed computer simulations using the HYSPLIT model. However, we 
took a different approach because we believe that Earthjustice's 
HYSPLIT analyses do not represent a comprehensive depiction of the dust 
event.\18\
---------------------------------------------------------------------------

    \18\ EPA does agree in part with the Jan Null declaration (EC, 
Exhibit H) in which he states that the data used by the District in 
the HYSPLIT model, EDAS (ETA Data Assimilation System) meso-scale 
data, is too coarse to account fully for both the complex terrain in 
and around the SJV and for the close proximity of the stations being 
examined. However, Earthjustice and EPA also used the EDAS meso-
scale data which are of sufficient resolution to account for the 
general overall wind flow in the southern SJV and thus provide a 
coarse simulation of wind trajectories within the Valley.
---------------------------------------------------------------------------

    While Earthjustice used trajectories starting at zero meters in 
height and took a two-dimensional approach in assessing the wind event, 
we took a more appropriate three-dimensional approach. The EPA approach 
recognizes that the dust did not stay at zero meters in height above 
ground but instead mixed up higher into the atmosphere where stronger 
winds occurred that caused the transport to be faster than 
Earthjustice's HYSPLIT analyses indicated. For September 22 and October 
25, 2006, for the morning start times, EPA ran trajectories at three 
heights: 10 meters, 100 meters and 250 meters. These heights were used 
to approximate the transport from near the surface, near the middle and 
near the top of the mixed layer \19\ as shown by the HYSPLIT model.
---------------------------------------------------------------------------

    \19\ The mixed layer is the unstable layer of the atmosphere in 
direct contact with the surface of the Earth. The daytime mixed 
layer is characterized by vigorous turbulent mixing. This means that 
air or dust laden air at any height within the mixed layer can 
impact the surface due to the mixing caused by turbulence.
---------------------------------------------------------------------------

    On September 22, 2006, based on the meteorological data and our 
HYSPLIT runs, the high winds that began in the Lemoore area around 6 
a.m. PST eroded and then transported dust that started to affect the 
PM-10 concentrations measured in the Corcoran area by 7 a.m. PST. See 
Figure 1, ``Forward Trajectories at 10, 100, & 250 meters, Lemoore Area 
to Corcoran, September 22, 2006, 6 a.m. to 8 a.m. PST.''\20\ From 
Corcoran and eastward, some of the dust may have been transported more 
towards the Sierra foothills. See Figure 2, ``Forward Trajectories at 
250 meters, Lemoore to Corcoran and Bakersfield, September 22, 2006, 6 
a.m. to 1 p.m. PST.'' West of Corcoran, the dust was transported 
southward towards Bakersfield, beginning to affect that area between 
the hours of 12 p.m. and 1 p.m. PST. See Figure 2 and Figure 3, 
``Forward Trajectories at 10, 100, & 250 meters, Lemoore Area to 
Bakersfield, September 22, 2006, 6 a.m. to 1 p.m. PST.'' Based on 
hourly PM-10 values, the peak concentration of dust, 725 [mu]g/m\3\, 
occurred at about 10 a.m. PST in Corcoran and a PM-10 value of 294 
[mu]g/m\3\ occurred at about 3 p.m. PST in Bakersfield. See Table 4 
above. See also our response to comment 21 below.
---------------------------------------------------------------------------

    \20\ The EPA Figures referenced in this final rule are available 
in the docket for this rulemaking action and are listed in section 
II.C. below.
---------------------------------------------------------------------------

    On October 25, 2006, the scenario was similar to September 22, 
2006. EPA's HYSPLIT runs support a finding that the high winds that 
began in the Lemoore area around 5 a.m. PST eroded and then transported 
dust that started to affect the PM-10 concentrations measured in the 
Corcoran area by about 6 a.m. PST. See Figure 4, ``Forward Trajectories 
at 10, 100, & 250 meters, Lemoore Area to Corcoran, October 25, 2006, 5 
a.m. to 7 a.m. PST.'' From Corcoran and eastward, some of the dust may 
have been transported more towards the Sierra foothills. West of 
Corcoran, the dust was transported southward towards Bakersfield, 
starting to affect that area between 11 a.m. and 12 p.m. PST. See 
Figure 5, ``Forward Trajectories at 250 meters, Lemoore to Corcoran and 
Bakersfield, October 25, 2006, 5 a.m. to 11 a.m. PST'' and Figure 6,'' 
Forward Trajectories at 10, 100, & 250 meters, Lemoore Area to 
Bakersfield, October 25, 2006, 5 a.m. to 11 a.m. PST.'' The peak 
concentration of dust in Corcoran occurred around 11 a.m. PST with a 
PM-10 value of 794 [mu]g/m\3\. The peak concentration of dust in 
Bakersfield was more obscure with a peak at about 5 p.m. PST and a PM-
10 value of 416 [mu]g/m\3\. See Table 5 above.
    EPA believes that our HYSPLIT analyses depict more accurately than 
Earthjustice's runs the windblown dust events of September 22 and 
October 25 because, in addition to accounting for the various heights 
above ground level, we accounted for the wind flows within the Valley 
more comprehensively. We recognized that the winds over the eastern 
portion of the Valley tended to move towards the east, winds over the 
western portion of the valley tended to move more towards the south, 
and that there was a transition area in between where winds moved 
southeast directly from the Lemoore area to Bakersfield. See Figures 2 
and 5 above. Thus we believe that our HYSPLIT analyses were sufficient 
to provide a general overview of the direction and speed of dust

[[Page 14701]]

transport in the San Joaquin Valley and support the contention of dust 
transport from the Lemoore area to the Corcoran and Bakersfield areas. 
Our analyses are also in general agreement with the measured wind data 
provided by the State which do account for the complex terrain of the 
Valley.
    We note again that our concurrence with the State's causal 
connection demonstration is based on the meteorological data for 
September 22 and October 25, 2006 discussed above. We believe the 
HYSPLIT model supports this demonstration by showing that the winds 
were of the appropriate intensity and direction to move a plume of dust 
from the central SJV to the Bakersfield areas on those days.
    Comment 12: Earthjustice claims that the exceedances in the SJV 
cannot be deemed to be in excess of normal historical fluctuations 
because they occur regularly and at a similar level every fall and are 
therefore no different from the exceedances used to designate the SJV 
nonattainment in the first place. Thus Earthjustice believes there are 
no ``unusual activities'' as EPA states, because the exceedances at 
issue here were caused by the same dust-generating activities that 
cause exceedances every year.
    Response 12: As we discussed in our proposed rule at 72 FR 49052, 
for EPA to concur with a state's claim that an exceptional event caused 
an exceedance, the state must show that the event is associated with 
concentrations that are beyond the normal historical fluctuations. See 
40 CFR 50.14(c)(3)(iii)(C).
    When the SJV was designated nonattainment for PM-10 in 1991 by 
operation of law (56 FR 11101, March 15, 1991), the District had not 
implemented the BACM for PM-10 that are currently in place. Since 1991, 
the State of California and the SJVAPCD have adopted many rules and 
rule amendments that have led to significant reductions in PM-10 and 
oxides of nitrogen (NOX) emissions. These rules include, as 
discussed above, BACM for fugitive dust sources such as unpaved and 
paved roads, vacant lots, construction sites, etc. (Regulation VIII) 
and BACM for agricultural sources (Rule 4550--Conservation Management 
Practices). See Section 8, ``Natural Event Documentation, Corcoran, 
Oildale and Bakersfield, California, September 22, 2006,'' April 20, 
2006. These BACM rules for fugitive dust and agricultural sources were 
adopted and implemented in mid- to late 2004. See 71 FR 8461 and 71 FR 
7683. Given the vast changes in regulatory requirements for PM-10 
sources, the dust-generating activities in the early 1990's are not, as 
Earthjustice suggests, comparable to those after the full 
implementation of BACM in the SJV. Therefore we do not believe that the 
September 22 and October 25, 2006 \21\ exceedances are the result of 
the same type of dust-generating activities that caused the area to 
originally become nonattainment. Nor do we believe that Earthjustice 
has substantiated its claim that they are.
---------------------------------------------------------------------------

    \21\ With respect to the exceedances at the Santa Rosa 
Rancheria, in the proposed rule EPA showed that the concentrations 
measured during the construction activity were in excess of normal 
historical fluctuations and that after completion of the paving 
project average PM-10 concentrations dropped by more than 50 
percent. 72 FR at 49062.
---------------------------------------------------------------------------

    We originally evaluated whether the September 22 and October 25, 
2006 exceedances exceeded normal historical fluctuations in our 
proposed rule. See 72 FR at 49053 and 49056. In response to 
Earthjustice's comment on the proposed rule that this EER criterion had 
not been satisfactorily demonstrated by the State's documentation, EPA 
undertook a further analysis of the data collected at the sites that 
exceeded the 24-hour PM-10 NAAQS on September 22, 2006 (Corcoran, 
Bakersfield-Golden State Highway and Oildale) and October 25, 2006 
(Corcoran and Bakersfield-Golden State Highway). EPA included data from 
1993 to 2006 in our analysis.\22\ Our statistical analysis shows the 
annual percentile values of the data from each of the three sites. In 
the preamble to our EER, we state that a comparison of the exceedance 
data to the historical 95th percentile values is appropriate for 
determining the level of evidence or documentation a state needs to 
provide in order for EPA to concur with its flagging request. Extremely 
high concentrations relative to the 95th percentile values would 
require a lesser amount of documentation to demonstrate that an event 
affected air quality. See 72 FR at 13569.
---------------------------------------------------------------------------

    \22\ 1993 was chosen as the starting point for data analysis 
because that is the year that the SJV was classified as a serious 
PM-10 nonattainment area.
---------------------------------------------------------------------------

    For Corcoran, when we examine all data collected since 1993,\23\ it 
is clear that the 95th percentile values have consistently been below 
the level of the 24-hour PM-10 NAAQS and since 1999 the Corcoran site 
has not recorded a 95th percentile value greater than 117 [mu]g/m\3\. 
The 95th percentile value recorded at Corcoran in 2006 was less than 
100 [mu]g/m\3\. Therefore, our analysis of all the data collected at 
Corcoran over the past 14 years indicates that the September 22 and 
October 25, 2006 exceedances were clearly beyond the normal range of 
annual concentrations recorded at this site. See Figure 7, ``Annual 
Peak Day PM10 Concentrations at Corcoran.''
---------------------------------------------------------------------------

    \23\ From 1993 through 1998, the Corcoran site collected PM-10 
data on a once every sixth day schedule using a Federal Reference 
Method (FRM) monitor. Beginning in 1999 the Corcoran PM-10 site has 
been collecting data on a once every third day schedule using FRM 
monitors. In October 2006 the SJVAPCD began operating a continuous 
monitor designated as a Federal Equivalent Method (FEM) monitor at 
the site to provide everyday PM-10 data to the public. The State and 
SJVAPCD report all data from these monitors to the EPA's AQS 
database.
---------------------------------------------------------------------------

    As with the Corcoran data, we performed a statistical analysis of 
the data collected at the Bakersfield-Golden State Highway site using 
data from 1993 to 2006 and calculated the annual percentile values. 
From this analysis it is clear that the 95th percentile values at 
Bakersfield were consistently less than the level of the 24-hour PM-10 
NAAQS. In 2006 the 95th percentile value at Bakersfield-Golden State 
Highway was 101 [mu]g/m\3\. Therefore our analysis of the Bakersfield-
Golden State Highway data shows that the September 22 and October 25, 
2006 exceedances were beyond the normal range of data recorded at this 
site during the past 14 years. See Figure 8, ``Annual Peak Day PM10 
Concentrations at Bakersfield.''
    Finally, our analysis of the data collected at Oildale also shows 
that the exceedance recorded at that site on September 22, 2006 was 
outside the normal range of historical values. As with the other two 
sites discussed above, the 95th percentile values recorded at Oildale 
during the past 14 years were consistently below the level of the NAAQS 
and the 95th percentile value in 2006 was 111 [mu]g/m\3\. Again, our 
analysis of the Oildale data indicates that the September 22, 2006 
exceedance recorded at this site was outside the normal historical 
fluctuation of data for the past 14 years. See Figure 9, ``Annual Peak 
Day PM10 Concentrations at Oildale.''
    Therefore, our analysis of all the annual data from 1993 through 
2006 shows that the September 22 and October 25, 2006 exceedances are 
in excess of normal fluctuations.
    To address Earthjustice's specific concern that these exceedances 
occur routinely in the fall months, defined by Earthjustice as the 
months of September, October and November,\24\ we performed the same 
statistical test on the Corcoran data using only those values recorded 
during those months. From this test it is clear that the 95th 
percentile values for all years since 1998 do not exceed the level of 
the 24-hour PM-10 NAAQS. The highest 95th percentile value since 1998 
was a 146 [mu]g/m\3\ recorded in 2003. Again, this

[[Page 14702]]

analysis demonstrates that the September 22 and October 25, 2006 
exceedances recorded in Corcoran, even when we use seasonally adjusted 
data, were in excess of the normal historical fluctuations. See Figure 
10, ``Annual Peak Fall Day PM10 Concentrations at Corcoran.''
---------------------------------------------------------------------------

    \24\ EC at 15.
---------------------------------------------------------------------------

    At the Bakersfield monitor, 95th percentile values for the fall 
months have been lower than the level of 24-hour PM-10 NAAQS since 
2000, with the highest 95th percentile value recorded in that year at 
145 [mu]g/m3. In 2006, the fall months' 95th percentile 
value was 100 [mu]g/m3. These values show that the 
exceedances measured on September 22 and October 25 were outside the 
historical fluctuation of data for the fall months. See Figure 11, 
``Annual Peak Fall Day PM10 Concentrations at Bakersfield.''
    Finally for Oildale, our analysis of the fall 95th percentile 
values shows that since 1996 the 95th percentile values have not 
exceeded the level of the NAAQS and 1996 had the highest 95th 
percentile value (138 [mu]g/m3), with the exception of the 
September 22, 2006 concentration of 162 [mu]g/m3. Even 
though the 95th percentile value in the fall of 2006 exceeded the level 
of the NAAQS, when we look at the historical fall data for Oildale this 
value does stand out as outside the normal range. See Figure 12, 
``Annual Peak Fall Day PM10 Concentrations at Oildale.''
    Therefore, our analysis of the data from 1993 through 2006 for the 
months of September through November shows that the September 22 and 
October 25, 2006 exceedances were in excess of normal fluctuations.
    Comment 13: Earthjustice argues that EPA cannot make the required 
``but for'' showing for the locations other than the SRR because either 
the model shows that the winds did not blow toward the monitors or the 
monitoring data show that the standard was being exceeded even before 
the alleged dust-laden winds arrived.
    Response 13: With respect to the September 22, 2006 exceedance, see 
our responses to comments 10, 11, 16 and 21. With respect to October 
25, 2006 see our responses to comments 10, 11 and 43. We also discussed 
the ``but for'' demonstration included in the State's documentation in 
detail in our proposed action. See 72 FR 49053, 49056-49057.
    Comment 14: Earthjustice also argues that to make its ``but for'' 
showing EPA asserts that no ``unusual activities'' occurred during the 
exceedance period and implies that something ``extra'' must have 
happened which would mean that an area would either have violations 
every day or never and that EPA would then have to conclude that unless 
an area violates every day, any violation must be the product of some 
exceptional, nonrecurring event. Earthjustice believes that EPA's 
reliance on this type of argument to make the ``but for'' claim is 
arbitrary and capricious.''
    Response 14: Earthjustice takes out of context EPA's consideration 
of the fact that there were no other unusual activities at the time of 
the September 22 and October 25, 2006 exceedances to draw some extreme 
conclusions, such as that the Agency would have to conclude ``that 
unless an area violates every day, any violation must be the product of 
some exceptional nonrecurring event.'' In this connection, Earthjustice 
misunderstands EPA's application of the weight of evidence approach to 
the ``but for'' demonstration. In the preamble to the EER, EPA 
explained that it would use a ``weight of evidence-based approach to 
demonstrate that there would not have been an exceedance or violation 
but for the event.'' 72 FR at 13570-13571. EPA explained that through 
analyses it was possible to demonstrate that an exceedance would not 
have occurred but for the event; however, this analysis does not 
require a precise estimate of the estimated air quality impact from the 
event. 72 FR at 13570.
    In applying this weight of evidence approach, EPA considered the 
totality of circumstances surrounding the events for the exceedance 
days. EPA included in its consideration, an evaluation of the coarse 
particles, information about geologic dust, values representing excess 
geologic contributions, comparison of ``adjusted'' PM-10 values with 
typical average concentrations during similar periods, information 
about control measures, readings on days before and after the 
exceedance days, and whether any unusual or out of the ordinary 
activities occurred on such days. See 72 FR at 49053. Monitor readings 
on the days before and after the event days indicated no violations. 
EPA therefore looked to see if on the specific event days there were 
activities that were different or unusual as compared to the days when 
there were no exceedances in order to rule those in or out as 
contributing to the exceedance. Contrary to Earthjustice's contention 
that any time there is a violation EPA would conclude that it is due to 
some exceptional nonrecurring event, the lack of unusual activities was 
just one of the factors that EPA considered in reaching its 
determination based on the weight of evidence analyses. Thus, EPA's 
consideration of whether or not there were unusual activities in this 
context is neither arbitrary nor capricious as Earthjustice claims.
2. Comments Specific to September 22, 2006--Corcoran, Bakersfield and 
Oildale
    Comment 15: Earthjustice claims that in order to show that an event 
has affected air quality, a demonstration must be made that the event 
``caused a specific air pollution concentration'' and that the data to 
be waived are directly due to the event. Earthjustice asserts that the 
District did not provide evidence that demonstrates how enough 
particulate matter pollution could have been generated in and 
transported from one remote area of the SJV to multiple monitors in 
distant locations within the time period of the event. In this regard, 
Earthjustice states that while the District cites a study that 
allegedly establishes a threshold at which wind begins to erode PM 
(sustained winds of 18 mph or gusts of 22.4 mph), there is no basis for 
the claim espoused by both the District and EPA that winds below this 
threshold velocity can then transport particulate matter pollution long 
distances. To support this assertion Earthjustice cites EPA's recent 
rulemaking (71 FR 61144, 61146, October 17, 2006) establishing new PM 
standards in which EPA concluded that ``thoracic coarse particles 
generally deposit rapidly on the ground or other surfaces and are not 
readily transported across urban or broader areas.''
    Response 15: Earthjustice states that in order to show that an 
event affected air quality the State must quantify the amount of PM-10 
initially generated at a source location. In our proposed rule we 
stated that this criterion (affecting air quality) is met by 
establishing that the event is associated with a measured exceedance in 
excess of normal historical fluctuations, including background, and 
there is a clear causal connection between the event and the 
exceedance. 72 FR at 49051. We also discussed how these criteria were 
met. Id. at 49051-49052.
    Earthjustice seems to be suggesting that in order to meet the 
criterion ``affects air quality'' the State should have used an air 
quality model such as AERMOD or CalPuff to show the behavior of 
fugitive dust. In other words, Earthjustice is asking for a modeling 
demonstration that would show, quantitatively, that a given amount 
(either in the form of an emission rate or initial ambient 
concentrations at the source regions) can produce a particular 
concentration at a receptor point (e.g., monitoring site location). 
This type of modeling, at the scale Earthjustice is suggesting, is not 
an

[[Page 14703]]

appropriate tool for use in this type of application because it cannot 
be performed with any degree of accuracy.
    The State included in its documentation the results of a study that 
determined the threshold wind speed needed to erode geologic material 
and entrain the resulting particles into the atmosphere.\25\ 
Earthjustice states that there is no basis for the claim that lower 
wind speeds could transport dust long distances.
---------------------------------------------------------------------------

    \25\ Subtask Memorandum, ``3.3 How Well Do Measurements 
Characterize Critical Meteorological Features,'' Dave Bush, T & B 
Systems, August 24, 2004.
---------------------------------------------------------------------------

    While the State did not provide information from a specific study 
to demonstrate wind speeds sufficient to transport PM-10 suspended in 
the atmosphere, EPA believes it is reasonable to conclude, as the State 
did, that if an 18 mph wind is sufficient to erode and entrain coarse 
particles into the atmosphere, a lower wind speed is sufficient to keep 
particles already entrained in the atmosphere suspended, and to 
subsequently transport them considerable distances. To erode geological 
material on the ground and cause it to be suspended in the air, winds 
must have enough kinetic energy to overcome the attractive forces 
between particles, in addition to gravitational forces. High winds also 
tend to cause large particles to collide with each other, making them 
break apart and become more likely to be lifted up. For particles that 
have already been lifted well above ground level, winds need only have 
enough occasional upward component (due to turbulence) to overcome 
gravitational settling. Also, winds aloft may have been stronger (and 
had more turbulence) than suggested by the ground based measurements.
    As presented in Table 3 of the State's documentation, the wind 
speeds between Lemoore and Corcoran, measured at Corcoran, reached a 
maximum speed of 11 mph between hours 6 and 12. See ``Natural Event 
Documentation, Corcoran, Oildale and Bakersfield, California, September 
22, 2006,'' San Joaquin Valley Unified Air Pollution Control District, 
April 20, 2007. Winds in the region between Corcoran and Bakersfield, 
measured at Alpaugh and Allensworth State Park, reached 16 mph and 15 
mph, respectively, between hours 10 and 16.\26\ EPA believes that wind 
speeds of this intensity were sufficient to transport PM-10 from the 
central SJV to the Bakersfield area.
---------------------------------------------------------------------------

    \26\ Wind speeds at Allensworth State park reached 20 mph and 35 
mph at hours 8 and 9. This indicates that while the area around 
Lemoore was identified as the source for the PM-10 on September 22, 
2006, additional PM-10 was likely generated by winds in the region 
between Corcoran and Bakersfield.
---------------------------------------------------------------------------

    Regarding Earthjustice's reference to the PM coarse NAAQS final 
rule, EPA was noting the difference in expected transport distances for 
PM-2.5 versus PM coarse. Note that we stated that coarse particles 
generally deposit rapidly on the ground or other surfaces and are not 
readily transported across urban or broader areas. 71 at 61146. When 
comparing PM-2.5 and PM coarse in urban settings it is true that PM-2.5 
is a more regional pollutant and can spread over great distances. PM 
coarse particles in urban areas, under meteorological conditions that 
do not involve high winds, generally are considered more of a localized 
pollutant problem. The statement cited by Earthjustice was not meant to 
imply that under windy conditions PM coarse particles would not be 
subject to transport. The exceedances that occurred in both Corcoran 
and the Bakersfield area on September 22 and October 25, 2006 were the 
result of windblown and transported dust from a predominantly rural 
area.
    Comment 16: Earthjustice provides a chart that it states 
demonstrates the range of sustained wind speeds in key areas of the 
central and southern SJV on September 22, 2006 with corresponding 
hourly PM-10 concentrations. With respect to this chart, Earthjustice, 
citing EPA Raw Data Reports, asserts the following:

    * * * there was a period of a few hours where the alleged wind 
speed threshold was exceeded at the Lemoore Naval Air Station 
monitoring site, which is located northwest of the city of Lemoore. 
The maximum sustained wind speeds ranged from 21 to 29 miles per 
hour between the hours of 7 a.m. and 11 a.m., and again exceeded the 
alleged threshold at 1 p.m. The maximum peak gusts (i.e., momentary 
bursts of wind) recorded at the Lemoore NAS ranged from 30-40 miles 
per hour between the hours of 9 a.m. and 11 a.m. However, just 10 
miles southeast of the Lemoore NAS at the Santa Rosa Rancheria, 
sustained winds never got any higher than 14.1 miles per hour * * *. 
In Corcoran, sustained winds reached only 9.6 miles per hour, and 
Bakersfield experienced nothing stronger than 7.8 mile-per-hour 
sustained winds * * *. None of the winds experienced outside of 
northwest Lemoore were capable of eroding soils and so none of these 
areas could have contributed any wind-entrained dust to the PM-10 
concentrations recorded on September 22, 2006.

    Response 16: As discussed in our response to comment 10, the 
Lemoore wind speeds included in the State's documentation were reported 
in PDT and not in PST. The Corcoran and Bakersfield PM-10 hourly 
concentration data were reported in PST which means that the winds in 
Lemoore began to exceed the threshold wind speed at 6 a.m. PST. The 
times for the wind speed data in the Earthjustice chart need to be 
adjusted accordingly.
    While we do not have monitoring data at every location, contrary to 
Earthjustice's comment, there are data that show the threshold wind 
speed was exceeded not only in the Lemoore area but at other locations 
in the central and southern SJV on September 22, 2006. The Lemoore 
station showed the most intense wind speeds in the area and the data 
are used to represent the conditions in the area centered around 
Lemoore. The nearest meteorological station to Lemoore is the Santa 
Rosa Rancheria monitoring station, located about 11 miles SE of 
Lemoore. However, the fact that the winds at the SRR did not exceed the 
threshold velocity does not prove that there were no wind speeds above 
the threshold between Lemoore and Corcoran. We obtained wind data from 
other meteorological stations in the central SJV such as Tranquility 
(30 miles NW of Lemoore), Selma (20 miles NE of Lemoore), Kettleman 
Hills (20 miles SSW of Lemoore), Hanford Municipal Airport (17 miles 
east of Lemoore), Hanford (18 miles east of Lemoore) and Allensworth 
State Park (43 miles SW of Lemoore). Wind speed data from these sites 
are presented in the Table 6 below.

                Table 6.--September 22, 2006 Morning Wind Speeds at Meteorological Monitoring Stations in the Central San Joaquin Valley
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                            Allensworth
 Time (a.m. PST)  Tranquility (hour/  Selma  (hour/gust)    Lemoore  (hour/     Kettleman Hills     Hanford Airport     Hanford  (hour/     State Park
                         gust)                                   gust)            (hour/gust)         (hour/gust)            gust)            (hour)
--------------------------------------------------------------------------------------------------------------------------------------------------------
6:20............  9/12..............  6/7...............  ND................  ND................  ND................  4/10..............              ND
6:30............  10/10.............  5/9...............  ND................  ND................  ND................  5/8...............              ND

[[Page 14704]]

 
6:45............  8/12..............  5/7...............  ND................  ND................  ND................  5/8...............               3
7:00............  9/11..............  6/9...............  21................  16/24.............  17/ND.............  5/7...............               6
7:20............  13/12.............  7/6...............  ND................  ND................  ND................  5/11..............               7
7:35............  13/14.............  7/7...............  ND................  ND................  ND................  5/11..............              ND
7:45............  14/14.............  8/9...............  28................  17/24.............  15/ND.............  7/10..............              38
8:05............  15/19.............  10/10.............  26................  ND................  ND................  8/12..............               5
8:15............  13/19.............  12/10.............  31................  ND................  ND................  9/12..............              20
8:30............  21/20.............  14/14.............  28/35.............  ND................  ND/26.............  9/17..............              21
8:45............  23/23.............  8/16..............  ND/35.............  ND................  ND................  7/18..............               9
9:00............  20/23.............  12/15.............  29/38.............  18................  15/ND.............  5/21..............               2
9:20............  18/27.............  12/18.............  24/40.............  ND................  ND................  4/18..............              35
9:35............  21/25.............  9/15..............  ND................  ND................  ND................  5/16..............               6
9:45............  17/25.............  6/16..............  ND/37.............  ND................  ND................  8/18..............               2
10:05...........  17/24.............  9/13..............  23/ND.............  20/27.............  10/ND.............  7/16..............              15
10:15...........  17/26.............  5/13..............  ND................  ND................  ND................  4/11..............               3
10:35...........  17/23.............  7/7...............  ND................  ND................  ND................  ND/13.............               9
10:50...........  14/23.............  8/12..............  ND/30.............  ND................  ND................  ND/13.............               0
11:05...........  16/21.............  7/7...............  17/ND.............  17/32.............  10/ND.............  ND/11.............              ND
11:15...........  12/22.............  7/12..............  ND................  ND................  ND................  ND................               8
11:30...........  14/20.............  1/9...............  ND................  ND................  ND................  ND................              10
11:35...........  15/23.............  ND/8..............  ND/24.............  ND/24.............  ND................  ND................              ND
11:45...........  ND/23.............  6/9...............  ND................  ND................  ND................  ND................               0
11:50...........  ND/23.............  ND/5..............  ND................  ND................  ND................  ND................              ND
12:00...........  ND/16.............  0.................  14/...............  17/ND.............  10/ND.............  ND................             ND
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: Mesowest historical meteorological data, Mesowest, http://www.met.utah.edu/mesowest/.
ND--No Data available.

    Earthjustice includes data in its chart only from locations which 
had recorded lower wind speeds on the morning of September 22, 2006. We 
addressed the lower intensity winds at Corcoran and Bakersfield in our 
proposed rule, and the fact that the winds between Lemoore and Corcoran 
and Bakersfield were capable of keeping in suspension the particulate 
matter that the winds at Lemoore had suspended. See 72 FR at 49052. 
Earthjustice does not include data from the other meteorological sites 
in the general area of the central SJV that show winds that were 
comparable to those recorded at the Lemoore Naval Air Station 
meteorological site. Data from these other meteorological sites, as 
shown above, indicate that nearly all recorded hourly wind speeds on 
September 22, 2006 were in excess of the threshold wind speed of 18 mph 
between 6 a.m. and 12 noon PST. Recorded gusts at some of these sites 
were also in the 20-30 mph range during the morning hours. It is likely 
that there were other places along the path from Lemoore to Bakersfield 
that experienced wind speeds above the threshold velocity but there 
were no wind instruments to document it.
    Therefore, Earthjustice's statement that none of the winds 
experienced outside of northwest Lemoore were capable of eroding soils 
is simply not true. Based on actual recorded wind data, wind speeds in 
the central SJV on the morning of September 22, 2006 were high not just 
in Lemoore but throughout this portion of the Valley. Moreover, as 
pointed out above, even if the winds outside of Lemoore were not 
capable of eroding soil, the winds between Lemoore and Corcoran and 
Bakersfield were capable of keeping in suspension the particulate 
matter that the winds in the area around Lemoore had entrained.
    Comment 17: Earthjustice states that no attempt was made to explain 
how high winds that began at 7 a.m. on September 22, 2006 caused 
violating PM-10 levels at a monitor 25 miles away starting at 6 a.m.
    Response 17: See responses to comments 10 and 11.
    Comment 18: Earthjustice asserts that EPA failed to demonstrate 
that the concentrations measured on September 22, 2006 could have been 
caused by the wind-generated erosion of soils from agricultural and 
industrial sources in the Lemoore area. Earthjustice states that all 
EPA offered as evidence is a study establishing a threshold velocity at 
which soil erosion may begin to occur, but that EPA has not analyzed 
whether the study's threshold wind speed is appropriate for the Lemoore 
area. Earthjustice argues that the scouring of soil by winds depends on 
much more than simply the speed of the wind and that EPA has not 
attempted to analyze factors pertinent to fugitive dust generation such 
as the soil class and erodibility in the Lemoore area, the types and 
stages of crop cover present at the time the winds occurred, the 
specific activities occurring in the area that contributed to PM-10 
concentrations, or the specific measures employed by sources to reduce 
or prevent wind erosion. Earthjustice maintains that this information 
should have been evaluated to help determine whether or not the winds 
in Lemoore could have realistically generated the levels of PM-10 
observed on September 22, 2006.
    Response 18: EPA has demonstrated that the concentrations measured 
on September 22, 2006 were caused by windblown dust generated in the 
Lemoore area. As stated above in response to comment 10, the State's 
documentation included a threshold wind speed needed to erode soils and 
entrain the resulting particulate matter in the atmosphere. This wind 
speed study was part of the 2002 CRPAQS Study. The wind speed study was 
performed in Angiola, California, which is located about 8 miles SW of 
Corcoran and 34 miles SW of Lemoore. Based on the soil map included in 
the State's documentation, the soil type in Angiola is the same as 
those in Lemoore and Corcoran. See ``Natural Event Documentation, 
Corcoran, Oildale and

[[Page 14705]]

Bakersfield, California, September 22, 2006,'' San Joaquin Valley 
Unified Air Pollution Control District, April 20, 2007 at 76. Thus the 
threshold velocity at which soil erodes identified in the study is 
appropriate for the Lemoore and Corcoran areas.
    Reviewing the graphic in the State's documentation, we see that 
crop types throughout the areas in question are predominantly field 
crops. Id. at 77. Other sources in this rural portion of the SJV could 
include, but are not limited to, agricultural activities, unpaved roads 
and construction activity. These types of sources are all subject to 
BACM. Id. at 32-33. These BACM are part of the approved serious area 
PM-10 plan for the SJV. See 69 FR 30006. Therefore, EPA did in fact 
evaluate the principal factors identified by Earthjustice, including 
wind speed, sources and whether they were controlled. See also our 
proposed rule at 72 FR 49051 and 49053.
    Comment 19: Earthjustice states that EPA must find that the 
documentation demonstrates a clear causal relationship between a 
measured exceedance and the alleged event. In this respect, 
Earthjustice, relying on a declaration of Jan Null (Null declaration), 
argues that the District's documentation concocts a barely-plausible 
story of severe scouring by winds not much greater than the alleged 
minimum velocity for entrainment, followed by rapid transport from one 
remote west-Valley location (Lemoore) down to Corcoran, where huge 
amounts of particulate matter were deposited on the monitor in order to 
cause violations, yet enough pollution was kept entrained by much 
slower winds to continue on for 60 miles down to Bakersfield and 
Oildale in substantial enough quantities to also cause violations in 
those locations. Earthjustice concludes that this ``story'' is 
unsupported by reliable meteorological evidence.
    Response 19: As discussed in EPA's proposed rule (72 FR 49046) and 
in responses to comments 11 and 16, the State did provide reliable 
meteorological data to support its demonstration that winds in the 
central and southern SJV were of the appropriate intensity and 
direction to cause and transport fugitive dust to the affected monitors 
at Corcoran and Bakersfield. EPA relied on these data, as well as other 
publicly available data, to concur with the State's request to find 
that the exceedances of the NAAQS on September 22, 2006 were due to an 
exceptional event.
    Furthermore, Earthjustice mischaracterizes the data used to support 
this action. It is not the case that winds were not much greater than 
the threshold wind speed of 18 mph; rather they were at times 
significantly higher and widespread in the central SJV. See Table 6 
above. Winds between Lemoore and Corcoran were of the appropriate 
direction and intensity to transport windblown dust to Corcoran, 25 
miles away. Winds in the areas south of Corcoran and north of 
Bakersfield were of sufficient intensity to transport suspended PM-10 
the 55 miles from Corcoran to Bakersfield.\27\ The timing, direction 
and intensity of the winds and hourly PM-10 concentrations at 
Bakersfield all support the demonstration of transport presented by the 
State. Based on the weight of evidence presented, EPA has concluded the 
State's documentation shows a clear causal relationship between the 
wind event and the exceedances in contrast to the ``barely-plausible 
story'' Earthjustice alleges.
---------------------------------------------------------------------------

    \27\ There may have been some deposition and dispersion of the 
dust plume, as discussed in our proposal at 72 FR at 49052, but 
enough material remained suspended to impact the Bakersfield area. 
The fact that the 24-hour average PM-10 concentrations in 
Bakersfield and Oildale were 157 [mu]g/m\3\ and 162 [mu]g/m\3\ 
compared to the 215 [mu]g/m\3\ recorded at Corcoran certainly 
indicates that some deposition or dispersion occurred along the 55 
mile pathway.
---------------------------------------------------------------------------

    Comment 20: Earthjustice states that the Figure 1 in the Null 
declaration shows that winds originating in Lemoore at 7 am, which is 
when the data in the record show elevated winds began, may have 
traveled to Corcoran, arriving around noon. However, Earthjustice 
states that because the Corcoran monitor began reading exceedances of 
the PM-10 standard at 6 a.m., EPA cannot claim the winds caused the 
Corcoran exceedance.
    Response 20: See our responses to comments 10 and 11.
    Comment 21: Earthjustice claims that the Figures 1, 2 and 3 in the 
Null declaration show that the winds that did reach Corcoran proceeded 
northeast toward the Sierra foothills and did not move in the direction 
of Bakersfield.
    Response 21: As discussed in our response to comment 11 above, EPA 
assumed a more realistic three-dimensional approach to using the 
HYSPLIT model than Earthjustice's two-dimensional approach. We also 
used a small range of starting points for our HYSPLIT runs, recognizing 
that simply because the available Lemoore meteorological data were from 
a single point at the Lemoore Naval Air Station, the data from that 
point represent meteorological conditions over a wider area. See 
footnote 11 above.
    Based on our more realistic inputs, we initiated three HYSPLIT 
runs, one starting half way between Lemoore and Kettleman City (about 
11 miles southwest from Lemoore), one at Lemoore, and one about 11 
miles northeast of Lemoore. EPA chose these two different starting 
locations outside of Lemoore because, based on the trajectory model, 
they more precisely depict the potential source regions for Corcoran, 
which is more east than south of Lemoore, and Bakersfield, which is 
more south than east of Lemoore. Since the Lemoore station can be 
considered representative of a larger area than Lemoore itself, the 
starting locations are considered part of the Lemoore area and dust was 
entrained from that entire area. Also, in support of that assumption, 
Hanford, which is about 15 miles east northeast of Lemoore, and 
Kettleman Hills, about 22 miles southwest of Lemoore, reported wind 
speeds above the threshold for the entrainment of dust.
    The results of our HYSPLIT runs show that from Corcoran and 
eastward, some of the dust may have been transported more towards the 
Sierra foothills, but west of Corcoran the dust was transported 
southward towards Bakersfield. See Figures 1, 2, and 3. These results 
are in general agreement with Jan Null's statement that:

    * * * winds out of Kettleman City continued down the western-
most side of the San Joaquin Valley, essentially following the 
contours of the Coastal Range. This is not unusual behavior for 
winds on the west side of the Valley, which are generally faster 
than winds in the rest of the Valley due to the orientation of the 
Sacramento and San Joaquin Valleys.

Null declaration at 11. Between Lemoore and Kettleman City, the winds 
were in transition from heading towards the east near Corcoran and 
following the Coastal Range as happened around Kettleman City. This 
caused the winds in a portion of that transition area to go in a direct 
path towards Bakersfield. In contrast to EPA's inputs to the HYSPLIT 
model, the inputs used by Jan Null did not reflect the wind flow 
structure in the Valley and did not demonstrate a comprehensive view of 
the meteorological events that took place during that day.
    Comment 22: Earthjustice believes that EPA was ``dazzled'' by the 
District's use of the HYSPLIT model even though the model is not an 
appropriate tool for post hoc simulation of localized meteorology and 
EPA did no analyses of its own. Earthjustice further states that the 
District's single run does not show the connection between Lemoore 
winds and the violating monitors that EPA apparently thinks it does.

[[Page 14706]]

    Response 22: See our response to comments 10, 11 and 21.
    Comment 23: Earthjustice maintains that the winds just south of 
Lemoore, in and around Corcoran and between Corcoran and Bakersfield 
never exceeded the ``alleged'' threshold velocity to entrain dust and 
the winds originating in Lemoore that did exceed such threshold could 
not have carried sufficient particles of PM on to Bakersfield and 
Oildale. Earthjustice concludes therefore that the timing, wind 
trajectories and the basic physics of wind movement do not support a 
causal connection between the Lemoore winds and the September 22, 2006 
exceedances.
    Response 23: See responses to comments 11 and 16.
    Comment 24: Earthjustice notes that the District highlights a 
single data point showing sustained winds of 15.2 mph for one hour in 
Alpaugh. Earthjustice believes this is troubling because the District 
is relying on data from the California Irrigation Management 
Information System (CIMIS) monitoring network that the T & B Systems 
Report says should be used with ``extreme caution.'' Earthjustice also 
believes that it is suspicious that the District puts forth data from 
this source while simultaneously providing almost none of the data it 
collects from its own meteorological sensors which are collocated with 
the monitors that record PM-10 concentrations.
    Response 24: Earthjustice quotes from the T & B Systems Report 
without providing the context of the warning to use the data with 
``extreme caution.'' In its report, T & B Systems state:

    CIMIS--This data set should be used with extreme caution. Two 
significant issues regarding the CIMIS data were noted. First, the 
fact that wind measurements are made at 2 meters instead of 10 
meters appears to result in the reported wind speeds decreasing by 
about 30 percent relative to those made at 10 meters. This can be 
corrected, for the most part, by using the standard power law 
adjustment. Second, the results brought about significant questions 
about the alignment of the wind direction system, with possible 
misalignments as much as 30[deg] noted. This potential problem was 
noted at a significant number of sites investigated. The QA program 
for the CIMIS network is not known.

``T & B Systems Contribution to CRPAQS Initial Data Analysis of Field 
Program Measurements, Final Report Contract 2002-06,'' Technical & 
Business Systems, Inc., November 9, 2004 at 3.
    The issue of the height of the measurements taken at CIMIS' 
meteorological stations was addressed by the State in its 
documentation.\28\ Winds measured at two meters above ground level 
(AGL) are generally lower than those measured at the standard 10 
meters.
---------------------------------------------------------------------------

    \28\ ``Addendum, Natural Event Documentation, Corcoran, Oildale 
and Bakersfield, California, September 22, 2006,'' May 23, 2007 at 
13.
---------------------------------------------------------------------------

    Regarding the alignment of the wind direction system, there were 
many other meteorological stations that provided data on wind direction 
and these showed that the winds were predominantly from the north and 
northwest on September 22, 2006.
    Any uncertainty regarding the quality assurance for the CIMIS data 
would carry more weight if we were relying solely on the CIMIS data. 
Most of the meteorological data included in the State's documentation 
\29\ as well as the additional data obtained by EPA \30\ and used to 
evaluate this exceptional event demonstration were from the District's 
meteorological stations and National Weather Service meteorological 
networks. Since the District does not operate any monitoring stations 
between Corcoran and Bakersfield, it did not have any District-
collected meteorological data for this region.
---------------------------------------------------------------------------

    \29\ ``Natural Event Documentation, Corcoran, Oildale and 
Bakersfield, California, September 22, 2006,'' San Joaquin Valley 
Unified Air Pollution Control District, April 20, 2007; ``Addendum, 
Natural Event Documentation, Corcoran, Oildale and Bakersfield, 
California, September 22, 2006,'' San Joaquin Valley Unified Air 
Pollution Control District, May 23, 2007.
    \30\ Mesowest historical meteorological data, Mesowest, http://www.met.utah.edu/mesowest/.
---------------------------------------------------------------------------

    Comment 25: Earthjustice believes that the District did little more 
than a blind search for the areas of the SJV that experienced winds 
that exceeded the ``alleged'' entrainment level and then concluded that 
pollution on September 22, 2006 must have originated from that area.
    Response 25: EPA believes that the State and EPA conducted a 
thorough evaluation of the possible cause of the September 22, 2006 
exceedances and considered potential sources, conditions and control 
measures at the time of the exceedances. We discuss in additional 
detail in our response to comment 16 the fact that a number of 
locations in the central SJV besides Lemoore experienced high winds on 
that day. After a consideration of the most likely cause of the 
exceedances and after evaluating all the circumstances, the State 
concluded that the unusually high winds in the Lemoore area caused the 
exceedances in Corcoran and Bakersfield on September 22, 2006. The 
State then established in its documentation the causal connection 
between the winds in the Lemoore area and the exceedances at Corcoran 
and Bakersfield.
    Comment 26: Earthjustice asserts that neither the District nor EPA 
offers any basis for the statement in the proposed rule at 72 FR 49051 
that ``wind speeds [in Corcoran], though not sufficient to erode dust, 
were sufficient to keep entrained and transported dust from the high 
winds at Lemoore suspended for the period during which the exceedances 
occurred.'' Earthjustice further asserts that because winds 10 miles 
southeast of Lemoore at the SRR never exceeded the entrainment 
threshold and no other relevant location outside of the area northwest 
of Lemoore experienced erosive winds, there is very little basis for 
the conclusion that a clear causal relationship exists between dust 
entrained in Lemoore and violations of the standard in Corcoran, 
Oildale and Bakersfield.
    Response 26: See responses to comments 10, 11, 15 and 16.
    Comment 27: Earthjustice asserts that EPA fails to show that the 
exceedances at Corcoran, Bakersfield and Oildale were outside normal 
historical concentrations. Earthjustice claims that dust-intensive 
agricultural activities occur in the fall and that none of the 
September 22, 2006 exceedances are significantly beyond the normal 
fluctuating range of air quality concentrations in the SJV. 
Earthjustice presents a chart that it says demonstrates that the 
September 22, 2006 readings are within the historical range of PM-10 
concentrations observed over the past 15 years during the fall season.
    Response 27: See our response to comment 12 above.
    Comment 28: Earthjustice states that EPA suggests in the 
Exceptional Events Rule that a contemporary comparison of all 
seasonally-adjusted data is appropriate for determining historical 
frequency of the measurements in question. However, Earthjustice says, 
because fall is the season with the highest PM-10 concentrations, the 
comparison is most appropriately made by looking at historical data 
from September through November. Earthjustice claims that because the 
District's documentation limits its comparison to September 
measurements over a 7 year period, the result is a ``typical value'' 
based only on the ``relatively good days monitored.''
    Response 28: See our response to comment 12 above.
    Comment 29: Earthjustice maintains that EPA asserts that because 
the September 22, 2006 measurements were higher than what the District 
claims is

[[Page 14707]]

the ``typical value'' for the month of September, these violations must 
have been caused by an exceptional event. Earthjustice claims that with 
this argument EPA is saying that any PM-10 exceedance should be ignored 
as exceptional which is an absurd assumption that would render the 
NAAQS meaningless.
    Response 29: EPA did not decide to exclude the data from September 
22, 2006 from its attainment finding simply because the data were 
outside of the typical range of values normally seen in these areas. 
The EER has a number of criteria that need to be met in order for us to 
concur with a State's request to exclude data from consideration, 
including a demonstration that the event affected air quality, a causal 
connection between the event and the exceedance value recorded, an 
analysis demonstrating that the recorded exceedance was outside the 
normal fluctuation of the data, and a demonstration that ``but for'' 
the event the exceedance would not have occurred. EPA evaluates how the 
State meets all of these criteria, in addition to the procedural 
requirements of the EER and determines, based on the weight of the 
totality of the evidence presented, whether to concur with the State's 
request. In this case, EPA believes that the State has met the 
``weight-of-evidence'' standard and has demonstrated that the cause of 
the exceedances on September 22, 2006 was a high wind exceptional 
event. See also our response to comment 12.
    Comment 30: Earthjustice states that if EPA had compared the 
September 22, 2006 data to data from other days on which exceedances 
occurred, it would have found that the September 22, 2006 readings are 
typical of bad air days in the fall in the SJV and therefore would not 
have been able to dismiss these violations as ``in excess of normal 
fluctuations.''
    Response 30: See response to comment 12.
    Comment 31: Earthjustice states that it reviewed EPA's AQS reports 
of monitoring data from the past ten years and found that in Corcoran, 
50 percent of all FRM readings showing elevated levels of PM-10 occur 
in September and October and that 95 percent occur in the period from 
September to January. Earthjustice states that although the numbers are 
lower in Bakersfield and Oildale, with 31 percent and 29 percent of 
elevated PM-10 readings, respectively, occurring in September and 
October, these numbers do not paint the picture of exceptionality the 
District and EPA claim. Instead, Earthjustice declares, these numbers 
confirm that the concentrations recorded on September 22, 2006 were 
within the normal historical range of PM-10 concentrations experienced 
in the central and southern SJV during the fall PM season when 
concentrations are historically at their highest.
    Response 31: As discussed in our response to comment 12, EPA 
analyzed data from these sites and determined that the concentrations 
recorded on September 22 and October 25, 2006 were well outside the 
normal historical fluctuation of data normally recorded at these sites. 
In its comment, Earthjustice analyzes what it states are ``elevated 
levels'' of PM-10 concentrations that were recorded at the Corcoran, 
Oildale, and Bakersfield-Golden State Highway sites. Earthjustice 
asserts that an ``elevated level'' is ``defined by EPA'' as 90 [mu]g/
m\3\ or greater.\31\ This is not the case. For the source of its 
definition, Earthjustice cites a Federal Register notice in which EPA 
proposed to approve a PM-10 maintenance plan for Wallula, Washington. 
In that proposed rule the 90 [mu]g/m\3\ or greater was a figure 
employed by the Washington State Department of Ecology for use in 
modeling a PM-10 maintenance demonstration. 70 FR 38076 (July 1, 2005). 
EPA did not endorse or adopt this level as a definition of what 
constitutes ``elevated levels'' of PM-10 for the purposes of performing 
an analysis of historical fluctuations for the EER, and Earthjustice's 
evaluation of ``elevated levels'' at the SJV monitoring sites is not 
based on an EPA definition of what constitutes ``elevated levels'' for 
this purpose.
---------------------------------------------------------------------------

    \31\ EC at 6, footnote 16.
---------------------------------------------------------------------------

    Comment 32: Earthjustice claims that the ``but for'' test requires 
a showing that without the winds scouring the soils near Lemoore, the 
monitors in Corcoran, Bakersfield, and Oildale would not have recorded 
violations of the PM-10 standard and that such a showing cannot be 
made. Specifically, Earthjustice asserts that the monitor in Corcoran 
was violating the PM-10 standard on September 22, 2006 before the winds 
in Lemoore even picked up. Earthjustice states that Table 3 of the 
District's April 20, 2007 documentation shows that the continuous 
monitor in Corcoran was recording concentrations in excess of 150 
[mu]g/m\3\ starting at 6 a.m. Earthjustice further maintains that Jan 
Null in his declaration states that there is no way the winds in 
Lemoore could transport entrained dust instantaneously from Lemoore to 
Corcoran.
    Response 32: We address these issues in our responses to comments 
10, 11, 16 and 21. In our proposed rule we also discussed how the State 
met the ``but for'' criteria. 72 FR at 49053.
    Comment 33: Earthjustice further asserts that the winds in Corcoran 
never even got above 11 miles per hour, so local wind entrainment of 
particulate matter is not a factor. Earthjustice concludes that 
activities in and around Corcoran must have been responsible for the 
high PM-10 concentrations on September 22, 2006, not winds from 
Lemoore.
    Response 33: We addressed the lower wind speed issue in Corcoran in 
our proposed rule at 72 FR 49052 and also in our responses to comments 
10 and 15. As we discussed in the proposed rule, the lower wind speeds 
in Corcoran do not preclude the transport of dust from the areas 
northwest of Corcoran. The wind data from September 22, 2006 show high 
winds in the area centered around Lemoore. It was this area northwest 
of Corcoran that contributed PM-10 to the air parcel that impacted the 
monitors at Corcoran and Bakersfield. While any sources in the local 
area represented by the Corcoran monitor may have contributed some PM-
10 to the total 24-hour average, it was the wind-generated dust from 
the area of Lemoore that contributed enough PM-10 to cause the monitor 
to record an exceedance of the 24-hour PM-10 NAAQS.
    Given the evaluation of all information and circumstances 
surrounding the exceedance at the Corcoran monitor on September 22, 
2006, the weight of evidence supports the conclusion that the windblown 
dust from the area of Lemoore rather than contributions from sources in 
the area represented by the Corcoran PM-10 monitor were the ``but for'' 
cause of the exceedance.
    Comment 34: Earthjustice argues that, even if 6 hours worth of 
readings from the Corcoran continuous monitor were removed starting at 
11 a.m., in order to account for the 6 hours during which winds in 
Lemoore exceeded the alleged threshold velocity, there is still a 
violation of the PM-10 standard. Therefore, Earthjustice concludes, 
there is no way the District can argue and EPA can concur that winds 
from Lemoore were the cause of the violation of the PM-10 standard in 
Corcoran on September 22, 2006.
    Response 34: As discussed in the preamble to the EER, EPA's 
historical practice has been to exclude a daily measured value in its 
entirety when an exceptional event causes that value. See 72 FR at 
13572. EPA is not aware of the existence of precise and universally 
applicable techniques that are administratively and technically

[[Page 14708]]

feasible and that could support partial adjustment of air quality data. 
Thus, the approach suggested by Earthjustice is not viable and is not 
permitted by the EER except in some very limited cases not applicable 
here. See also response to comments 10.
    Moreover, Earthjustice suggests that the winds from Lemoore began 
affecting the Corcoran monitor at 11 a.m. In fact the Lemoore area 
experienced winds higher than the threshold wind speed beginning at 6 
a.m. PST and these winds likely began affecting the monitor at Corcoran 
between 7 and 8 a.m. PST (the value reported for 7 a.m. PST). See 
response to comment 10. When the winds at Lemoore decreased to levels 
below the threshold wind speed at 2 p.m. PST, the dust entrained in the 
atmosphere most likely still continued to impact the Corcoran monitor, 
though we see a leveling off and then gradual decrease in hourly PM-10 
concentrations from that point forward. See Table 3 above in our 
response to comment 10. We further addressed this timing question by 
performing our own HYSPLIT analyses. See response to comment 11 above. 
The result of our analysis of the winds on September 22 supports the 
State's demonstration that winds originating in the area around Lemoore 
starting at 6 a.m. PST could have transported dust and impacted the 
Corcoran monitor within one to two hours. See Figures 1 and 2.
    Earthjustice appears to assume that particles are deposited as soon 
as winds decrease below the threshold speed for entrainment; in fact, 
PM-10 particles remain in suspension for many hours after being 
entrained and, as in the case of Corcoran, continued to affect 
concentrations recorded at the monitor until the early evening hours of 
September 22, 2006. Thus, Earthjustice assumes that the windblown dust 
started to affect the concentrations monitored at Corcoran many hours 
later than it did in fact, and that it ceased to impact the monitor 
many hours before it did in fact. Thus EPA believes that the impact on 
the monitor started earlier and ended later than Earthjustice contends, 
and was thus the ``but for'' cause of the exceedance.
    Comment 35: Earthjustice maintains that there is no support for the 
claim that but for the winds originating in Lemoore, the monitors in 
Bakersfield and Oildale would not have exceeded the PM-10 standard. 
Earthjustice states that Jan Null shows in Figures 1, 2 and 3 in his 
declaration that the winds originating in Lemoore may have reached 
Corcoran at some point in the day, but they certainly did not continue 
on to Bakersfield and Oildale. Earthjustice states that the 
trajectories of winds out of Lemoore and Corcoran were decidedly away 
from Bakersfield and could not have carried particulate matter to 
Bakersfield and Oildale to cause the violations of the standard seen in 
these locations. Earthjustice states that Figure 4 in Jan Null's 
declaration shows that, in fact, any winds arriving in Bakersfield by 1 
p.m. were slow and moving in a circular pattern up from the southwest. 
Further, Earthjustice asserts that, as illustrated in Table A-1 of the 
District's May Addendum to its April 20, 2007 documentation, wind 
speeds in the Bakersfield area never reached speeds capable of eroding 
soils.
    Response 35: We have previously addressed the issue of dust 
transport to Bakersfield in our responses to comments 10, 11, 15, 16 
and 21. EPA does not contend that the wind speeds in Bakersfield 
reached the speeds necessary to erode and entrain dust, but rather that 
windblown dust from the area beginning in Lemoore and moving south 
affected the monitors in Bakersfield.
    The trajectory calculation that Jan Null used for Bakersfield was 
not illustrative of the complete meteorological scenario. Again, he 
used a single trajectory calculation starting at zero meters height 
which does not account for the third dimension of height of the dust 
above ground level. In HYSPLIT runs performed by EPA, forward 
trajectory calculations within the mixed layer starting between Lemoore 
and Kettleman Hills show transport directly to Bakersfield within 7 
hours.
    In addition, the circular wind pattern or eddy near Bakersfield 
discussed by Earthjustice was produced by a HYSPLIT analysis using a 
backward trajectory. However there appears to be a discrepancy between 
forward trajectories and backward trajectories produced by the HYSPLIT 
model. In source-receptor determinations, forward trajectories are 
considered more appropriate in determining precise locations of sources 
because they more accurately account for where the weather is coming 
from. EPA's forward trajectories did not show any indication of an 
eddy. The eddies that Earthjustice states occurred around Bakersfield 
are around 15 km in size for September 22, 2006. Since the EDAS 
meteorological data used for the trajectories has 40 km spacing between 
each grid point or meteorological data point, it is not of high enough 
resolution to accurately represent an eddy in the 15 km size range. 
There is too much uncertainty to conclude that there is an eddy because 
it is less than one grid cell spacing in dimension and would be 
considered a sub-grid scale feature. Thus, EPA's HYSPLIT runs, using 
more appropriate height levels in the atmosphere and forward 
trajectories, support the conclusion that the winds transported dust 
from the Lemoore area and caused the exceedances recorded at the 
monitors in the timeframe of the exceedances.
    Comment 36: Earthjustice argues that, in evaluating the ``but for'' 
demonstration, no attempt was made to determine which of the many 
diverse sources that contribute to particulate matter concentrations in 
the SJV might have been contributing to the pollution load and in what 
quantities on September 22, 2006. Earthjustice concludes that for EPA 
to declare that no ``unusual activities'' were taking place on this day 
is to say that the same dust-generating sources that have always caused 
periodic violations of the standards in the fall were again responsible 
for exceedances.
    Response 36: See responses to comments 6, 12 and 14.
3. Comments Specific to October 25, 2006--Corcoran and Bakersfield
    Comment 37: Earthjustice states that the documentation for the 
exceedances on October 25, 2006 is remarkably similar to that of 
September 22, 2006, and as such, suffers from the same significant 
flaws. Earthjustice also states that since the meteorology for both 
days was very similar, much of its analysis for September 22, 2006 also 
applies to October 25, 2006. Earthjustice provides a chart which it 
contends shows that wind speeds in Lemoore on October 25 were very 
similar to wind speeds on September 22. With respect to this chart, 
Earthjustice asserts the following:

    * * * there was a period of several hours during which the 
alleged wind speed threshold was exceeded in northwest Lemoore at 
the Naval Air Station monitor, though again wind speeds at the Santa 
Rosa Rancheria monitor only 10 miles southeast never reached that 
threshold. * * * Winds in Corcoran never got above 11.3 miles per 
hour and Bakersfield, likewise, did not exceed the District's 
alleged entrainment threshold with maximum winds just under seven 
miles per hour. * * * Further, the District can point to no data 
between Lemoore and Bakersfield that show winds capable of 
entraining dust, offering instead only data from CIMIS stations 
located far to the north and west that experienced higher wind 
speeds on October 25, 2006. As has already been established by Mr. 
Null, higher wind speeds on the west side of the Valley along the 
Coastal Range are not unusual due to the orientation of the 
Sacramento and San Joaquin Valleys. * * *

    Response 37: To the extent there are similarities between 
Earthjustice's

[[Page 14709]]

analyses for September 22 and October 25, 2006, EPA's responses to 
comments regarding September 22 are also applicable.
    In addition, EPA notes that the wind speeds in the central SJV, as 
represented by the meteorological monitoring station at Lemoore, on 
October 25 were quite high, reaching hourly average speeds of 31 mph 
and gusts of up to 40 mph, and were sustained at levels above the 
threshold wind speed for 11 hours (5 a.m. to 3 p.m. PST),\32\ as shown 
in Table 5 above. We do not contend that the wind speeds in the 
vicinity of Corcoran and Bakersfield were sufficient to entrain dust 
but, like September 22, 2006, the windblown dust generated in the 
Lemoore area in the central SJV was the ``but for'' cause of the 
exceedances recorded in Corcoran and Bakersfield on October 25, 2006. 
Moreover, the wind speeds that occurred in between Lemoore and Corcoran 
and Bakersfield were of sufficient speed to transport the entrained 
dust from Lemoore to the affected areas. Id.
---------------------------------------------------------------------------

    \32\ As discussed in response to comment 10 above, the 
meteorological data for Lemoore must be adjusted to correct for 
Daylight Savings Time.
---------------------------------------------------------------------------

    Earthjustice again selectively presents meteorological data to 
support its own position and neglects to include other data that 
support the State's demonstration. From the data supplied by the State 
in its documentation as well as additional publicly available data, it 
is clear that wind speeds in Lemoore, as well as throughout the central 
San Joaquin Valley, were either in excess of the threshold wind speed 
for entrainment (18 mph) or of sufficient intensity to transport dust 
from the Lemoore area to Corcoran and the southern SJV. See Table 7 
below.

                 Table 7.--October 25, 2006 Daytime Wind Speeds at Meteorological Monitoring Stations in the Central San Joaquin Valley
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                        Hanford     Kettleman
                             Hour                                Mendota    Tranquility    Lemoore      Airport    Hills (hour/   Alpaugh    Wasco (hour/
                                                               (hour/gust)  (hour/gust)  (hour/gust)  (hour/gust)     gust)        (hour)     dir/gust)
--------------------------------------------------------------------------------------------------------------------------------------------------------
6............................................................        12/ND         9/15        22/30        17/23        11/21          3.5       2/SW/3
7............................................................        15/20        10/17        22/32        15/ND        20/28          2.9            0
8............................................................        18/25        13/19        26/36        17/ND        15/27          5.6     7/NNW/15
9............................................................        17/30        20/22        29/39        24/29        19/32         16.9     5/NNE/18
10...........................................................        22/31        17/21        31/37        20/28        25/35         16.5       9/N/22
11...........................................................        22/30        15/20        30/40        15/24        25/35         16.8       7/N/15
12...........................................................        21/28        17/20        28/38        12/21        24/45         15.6       6/N/16
13...........................................................        20/28        15/23        26/35        12/ND        25/34         14.8       8/N/16
14...........................................................        18/29        18/19        22/31         9/ND        21/35         13.2     2/NNE/10
15...........................................................        12/23        10/18        20/26        12/18        22/33         13.3      ND/N/12
16...........................................................        15/20         8/17        14/ND         8/16        15/28         12.7        3/N/7
17...........................................................         8/17         4/10         3/ND         8/ND         9/22          6.5       2/N/ND
18...........................................................          5/6          1/5         6/ND         6/ND        10/14          4.4            0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: Mesowest historical meteorological data, Mesowest, http://www.met.utah.edu/mesowest/.
ND--No Data available.

    South of Corcoran, wind speeds measured at Alpaugh,\33\ 15 miles 
SSE of Corcoran and 44 miles NW of Bakersfield, were close to exceeding 
the threshold wind speed and as such were sufficient to transport 
particulate matter from the Lemoore area to Bakersfield as discussed 
above and in our proposed action. Furthermore, meteorological data from 
a station in Wasco, 40 miles SSE of Corcoran and 25 miles NW of 
Bakersfield and not part of the CIMIS network, recorded data that 
indicate that the daytime winds, while not high enough to erode soils, 
were predominantly from the north.
---------------------------------------------------------------------------

    \33\ See response to comment 24.
---------------------------------------------------------------------------

    Comment 38: Earthjustice states that like the documentation for 
September 22, 2006, the District's documentation for the alleged 
October event also fails to analyze the actual ability of the area to 
generate particulate matter concentrations in quantities great enough 
to cause the exceedances, fails to provide anything more than anecdotal 
evidence of activity levels and compliance with dust controls, and 
therefore fails to demonstrate that the winds in Lemoore affected air 
quality at all. Earthjustice states that, like the case for the 
September 22 demonstration, a claim that the wind entrained significant 
amounts of dust requires looking at more than just the wind speeds in 
the area. There are many factors that EPA and the District failed to 
support with any reliable and accurate data, starting with whether 
there was any dust available to be entrained.
    Response 38: See responses to comments 6, 14 and 18. As is the case 
with the September 22, 2006 documentation, the State has evaluated a 
variety of factors and circumstances to demonstrate that windblown dust 
caused the exceedances on October 25. See ``Natural Event 
Documentation, Corcoran and Bakersfield, California, October 25, 
2006,'' San Joaquin Valley Unified Air Pollution Control District, 
April 23, 2007 at section 7.
    The State also provided information on the inspection and 
compliance activities that were conducted on October 25, 2006. Section 
9.2 of the State's documentation lists the number of inspections and 
the location of inspection activity and indicates that the District was 
actively enforcing its rules on October 25, 2006. Two newspaper 
accounts of the high winds that occurred on October 25, 2006 provide 
independent verification of meteorological conditions. This type of 
documentation has been historically used to support these types of 
exceptional events requests. EPA's EER states that the simplest 
demonstrations could consist of newspaper accounts or satellite images 
to demonstrate that an event occurred together with daily and seasonal 
average ambient concentrations to demonstrate an unusually high ambient 
concentration level, which is clearly indicative of an exceptional 
impact. 72 FR at 13573.
    Comment 39: Earthjustice states that, as explained in its comments 
for September 22, 2006, the generation of particulate matter from winds 
of the

[[Page 14710]]

type experienced on October 25, 2006 could have been controlled or 
prevented had reasonable controls been required of dust-producing 
sources. Earthjustice believes that the fact that the District is 
trying to blame winds only slightly above the alleged wind speed 
threshold, and significantly below the velocities at which the 
aforementioned controls stop being effective, suggests that either 
winds could not have entrained dust or the reasonable measures 
referenced in the proposal were not actually in place at the time of 
the event.
    Response 39: See responses to comments 5, 6 and 7. The winds in the 
Lemoore area on October 25 were not ``slightly above'' the wind speed 
threshold but rather included sustained high winds between 26 and 31 
mph with gusts ranging from 26 to 40 mph. These wind speeds were 
clearly sufficient to entrain and transport PM-10.
    Comment 40: Earthjustice states that high winds entraining dust may 
qualify as a natural event, but it also believes the source of the dust 
is of equal importance under the law. Earthjustice states that EPA 
admits that on October 25, 2006, the wind-entrained particulate matter 
originated from anthropogenic sources such as agricultural and 
industrial activities, but that under the EER, only ``an event in which 
human activity plays little or no direct causal role'' can be 
considered a natural event. Earthjustice states that Congress did not 
intend for exceptional events to include sources that are caused by 
human activity. Alternatively, Earthjustice states that the source of 
the dust cannot be considered a non-recurring human activity, as 
agricultural and industrial activities are a constant source of 
emissions in the Valley.
    Response 40: See response to comment 5. Also, regarding 
Earthjustice's argument that dust from agricultural and industrial 
activities cannot be considered a non-recurring human activity because 
these activities are a constant source of emissions in the Valley, EPA 
does not consider (and has not stated anywhere) that normal 
agricultural and industrial activities are ``non-recurring human 
activity'' because such human activities often recur on a regular 
basis. By contrast, examples of non-recurring human activities may 
include major construction projects such as highways if they meet the 
criteria and requirements established in the EER. However, a recurring 
natural event such as a high wind event may entrain dust from 
anthropogenic sources. The entrainment of dust from ``reasonably 
controlled sources'' such as agricultural sources does not convert a 
natural event that qualifies as a high wind event into a recurring 
human activity which appears to be the result Earthjustice is seeking.
    Comment 41: Earthjustice states that, like the September 22, 2006 
documentation, the District did not provide the requisite amount of 
time for public comment on its October 25, 2006 documentation and did 
not re-publish its final documentation after radically changing its 
rationale. These procedural deficiencies alone should give EPA pause in 
considering the District's requests to flag this data.
    Response 41: See response to comment 8.
    Comment 42: Earthjustice states that since the meteorology on 
October 25, 2006 is so similar to that of September 22, 2006, it is not 
surprising that a causal connection cannot be established for October 
25 either. Earthjustice points out that the Corcoran monitor began 
reading concentrations above the national standard at 6:00 am, the same 
time that the winds in Lemoore, 25 miles away, began exceeding the 
District's alleged wind speed threshold at the same time. Earthjustice 
believes that it should go without saying that it is not possible for 
winds in Lemoore to transport entrained dust to Corcoran 
instantaneously, which is what would have to be the case if we are to 
believe the District's claims that those winds caused the exceedances 
in Corcoran, and that therefore, something other than the Lemoore winds 
caused the initial exceedances recorded at that monitor.
    Response 42: See responses to comments 10 and 11.
    Comment 43: Earthjustice states that even if we were to assume that 
the winds carried dust from Lemoore to Corcoran, the trajectory of 
those winds does not support the conclusion that the dust then moved 
down to Bakersfield. Earthjustice cites Figure 7 in the Null 
declaration which shows that winds originating in Lemoore moved on a 
due-east path toward Hanford and Corcoran and continued on toward the 
Sierra foothills. Jan Null uses HYSPLIT to determine the source of wind 
parcels arriving in Bakersfield at noon, which is approximately when 
the exceedances began, and shows that the same slow eddy effect that 
occurred on September 22, 2006 was also occurring in Bakersfield on 
October 25, 2006, which means that the winds impacting Bakersfield 
during the time of the exceedances were coming in slowly from the 
southwest. Figure 8 in the Null declaration.
    Response 43: As discussed in our responses to comments 11 and 21 
above, EPA assumed a more realistic three dimensional approach to using 
the HYSPLIT model than did Jan Null. We also used a small range of 
starting points for our HYSPLIT runs, recognizing that although the 
available Lemoore meteorological data were from a point located at the 
Lemoore Naval Air Station, the data represent conditions over a wider 
area. See footnote 11 above.
    As with our analysis of the September 22, 2006 event, we initiated 
three HYSPLIT runs for October 25, 2006, one starting half way between 
Lemoore and Kettleman City (about 11 miles southwest from Lemoore), one 
at Lemoore, and one about 11 miles northeast of Lemoore. On October 25, 
2006, the HYSPLIT trajectory presented by Null in Figure 7 of his 
declaration indicates that the winds starting in Lemoore went to the 
east southeast. However, EPA's HYSPLIT runs initiated half way between 
Lemoore and Kettleman City, northwest of Corcoran, demonstrate that the 
winds continued down the SJV towards Bakersfield, along a path just 
west of Corcoran. See Figures 5 and 6 above. Between Lemoore and 
Kettleman City, the winds were in transition from heading towards the 
east near Corcoran and following the Coastal Range as happened around 
Kettleman City. This caused the winds in a portion of that transition 
area to go in a direct path towards Bakersfield. See Figure 5.
    For Bakersfield, Null used a trajectory in Figure 8 of his 
declaration at zero meters height to show the same eddy effect 
occurring on October 25 as on September 22. Again, this height does not 
take into account dust mixing up into the atmosphere. In EPA's HYSPLIT 
runs, more appropriate forward trajectories were used which showed that 
dust coming from the Lemoore area could have reached Bakersfield within 
about 6 hours. See Figure 6. They also did not show any indication of 
the eddy effect near Bakersfield that Earthjustice found with back 
trajectories. Id. and response to comment 35. This supports the 
conclusion that dust-laden winds from the Lemoore area reached 
Bakersfield on October 25, 2006 consistent with the impacts reflected 
at the Bakersfield monitor.
    Comment 44: Earthjustice states that while the District and EPA 
cite wind speeds averaging 12 miles per hour in Alpaugh, an area 15 
miles south of Corcoran, neither agency provides a basis for concluding 
that such winds could transport and keep suspended the plume of 
entrained dust that was allegedly carried to Bakersfield, nor do they 
explain how the evidence provided

[[Page 14711]]

even suggests such transport could have taken place.
    Response 44: See responses to comments 11, 15 and 43. EPA finds 
that the documentation does establish a clear causal relationship 
between the winds in Lemoore and the exceedances in Corcoran and 
Bakersfield. See ``Natural Event Documentation, Corcoran and 
Bakersfield, California, October 25, 2006,'' San Joaquin Valley Unified 
Air Pollution Control District, April 23, 2007. Earthjustice neglects 
to consider that the CIMIS data need to be adjusted, as discussed in 
the State's documentation, due to the fact that CIMIS stations collect 
data at 2 meters above ground level as opposed to the standard 10 meter 
height. Id. at 25. See also response to comment 24. When this 
adjustment is made, we can see that the wind speeds at Alpaugh would 
have been approximately 25 percent higher at 10 meters than at 2 
meters. Winds at nearly 17 mph were recorded from 9 a.m. to 11 a.m. 
PST, dropping to between 15 mph and 13 mph between 12 p.m. and 3 p.m. 
PST. The lower wind speeds recorded at stations farther south, such as 
Shafter and Arvin, are consistent with the State's demonstration that 
after the winds in the central SJV transported particulate matter 
southward, lower wind speeds in the Bakersfield area facilitated the 
settling of the particulates at the monitoring station.
    Comment 45: Earthjustice states that while the readings from 
October 25, 2006 were relatively high, they were probably not beyond 
the normal historical fluctuations experienced in the Valley in late 
October. Earthjustice also states that fall is when the Valley's PM-10 
concentrations are at their highest and also the peak season for many 
dusty crops in the Valley.
    Response 45: See our responses to comment 7 and 12 above.
    Comment 46: Earthjustice states that EPA's ``but for'' analysis for 
the October 25, 2006 event is based entirely on speculation and 
conjecture and that EPA cannot say for sure what activities were taking 
place in the areas of Corcoran or Bakersfield and cannot say for sure 
that without the alleged high winds in Lemoore the monitors in Corcoran 
and Bakersfield would not have exceeded the standard.
    Response 46: See responses to comments 6 and 7 and EPA's ``but 
for'' analysis in our proposed rule at 72 FR 49056-49057. EPA's 
conclusion is not based on speculation and conjecture but rather on the 
weight of evidence presented.
    Comment 47: Earthjustice states that since the HYSPLIT analyses 
provided both by the District and by meteorologist Jan Null contradict 
the claim that the winds from Lemoore had a sufficient speed or 
trajectory to impact Corcoran and Bakersfield, and because the Corcoran 
and Bakersfield monitors were already measuring exceedances of the PM-
10 standard before the winds from Lemoore could have arrived, EPA 
cannot conclude that the District has established that ``but for'' the 
winds in Lemoore, the exceedances would not have occurred.
    Response 47: See responses to comments 10, 11, 21, 43 and 44.

B. Other Comments

    Comment 48: A commenter notes that the concept of exceptional 
events for air quality purposes is ``a bad idea'' because they provide 
a loophole to gut the intent of the original regulation. The commenter 
expresses concern that discarding data related to exceptional events 
would substantially weaken the regulation designed to protect the 
health of residents in an area. In the particular instance of the SJV, 
the commenter notes that the exceptional events were high winds and 
construction activity. According to the commenter, these events should 
not be used to justify poor air quality because high winds are a 
natural occurrence and construction activity occurs repeatedly. The 
commenter expresses concern that exceptional events not be used as 
``additional excuses to rationalize bad air on certain days.''
    Response 48: Congress amended section 319 of the CAA and required 
EPA to establish regulations governing the review and handling of air 
quality monitoring data influenced by exceptional events. In amending 
section 319, Congress indicated that states should not have to prepare 
and implement regulatory strategies designed to remedy poor air quality 
when their air quality is affected by events beyond their reasonable 
control. To accomplish this goal, Section 319, as amended, defined an 
exceptional event and required EPA to set certain minimum substantive 
and procedural requirements before data could be excluded as due to an 
exceptional event. In response, as described below, EPA proposed 
regulations for exceptional events in March 2006 and sought public 
comments on its proposal. See 71 FR 12592 (March, 10, 2006). In March 
2007, after considering all comments received, EPA published its final 
rule on exceptional events which became effective on May 21, 2007. 72 
FR 13560. During the exceptional events rulemaking process, EPA took 
comments on the definition of exceptional events, the substantive and 
procedural requirements for an event to qualify as an exceptional event 
and appropriate mitigation measures in these circumstances. In this 
rulemaking on air quality in the SJV, EPA is neither seeking nor 
considering comments on the concept of exceptional events, which 
activities would constitute exceptional events, and/or whether air 
quality data may be excluded due to such events. EPA has already 
addressed these issues in its EER. Comments about the concept of 
exceptional events and whether such events should be considered in air 
quality determinations have been decided in the exceptional events 
rulemaking process and thus are outside the scope of this rulemaking.
    The commenter also notes that as a general matter high winds should 
not be considered an exceptional event because they are natural 
occurrences. EPA has discussed high wind events extensively in the 
preambles to both the proposed and the final rules on exceptional 
events. The EER indicates the circumstances under which high winds can 
qualify for treatment as exceptional events. Again, these general 
issues were decided in the EER and EPA did not reopen comment on that 
general issue in this SJV rulemaking. The commenter does not provide 
data relevant to whether the high winds in this instance meet the 
provisions of the EER, the issue under consideration in this rulemaking 
action.
    The commenter asserts that ``construction is always occurring'' and 
therefore data related to these events should not be excluded. Not all 
construction activity qualifies as an exceptional event. A construction 
activity, like other exceptional events must meet the definitional, 
substantive and procedural requirements specified in the EER. For 
example, for any construction activity to be considered an exceptional 
event, it must meet the definition of an exceptional event, including 
for anthropogenic events such as construction, that it is an event that 
is unlikely to recur at that location. Thus, by definition, 
construction activity that is ``always occurring'' at a particular 
location is not an exceptional event under the rule.
    Comment 49: The commenter states that he is unfamiliar with details 
of the SJV case but wishes to comment on the concept of exceptional 
events and expressed his view that such events should not be considered 
in air quality determinations. The commenter believes that there are a 
wide variety of loopholes such as permitting rounding down of numbers, 
exclusion of three worst days and using three year

[[Page 14712]]

averages for final attainment which ``degrade the rigor of the 
standard.'' According to the commenter, excluding air quality data 
affected by exceptional events further softens the initial regulation. 
In the SJV case, the commenter questions why the construction activity 
was not limited to periods when the atmosphere could ``handle the 
load.'' In addition, the commenter discusses the construction of an 
asphalt plant in a local community and notes that during the 
construction of such a plant, officials sought to exclude data on 
certain days because they attributed the poor air quality to interstate 
transport. The commenter also refers to the treatment of fires in his 
area.
    Response 49: With respect to that portion of the comment concerning 
the concept of exceptional events, see response to comment 48. In 
response to the commenter's question about why the construction 
activity was not limited to periods when the atmosphere could handle 
the load, EPA notes that air quality ``load'' is not an issue for the 
SRR area where construction contributed to the exceptional event. There 
have been no exceedances or air quality issues in the SRR area either 
before or after the construction activity. As explained in the proposed 
rule, the monitor in the SRR was affected by the construction activity 
because it was in such close proximity to the construction activity 
(25-100 feet). 72 FR at 49062. The monitor has not recorded any 
exceedances since the construction activity at the parking lot was 
completed. The comments on the construction of the asphalt plant and 
the fires do not relate to issues in the SJV area and thus are outside 
the scope of this rulemaking.

C. List of EPA Figures in Docket

     Figure 1. ``Forward Trajectories at 10, 100, & 250 meters, 
Lemoore Area to Corcoran, September 22, 2006, 6 a.m. to 8 a.m. PST,'' 
March 6, 2008.
     Figure 2. ``Forward Trajectories at 250 meters, Lemoore to 
Corcoran and Bakersfield, September 22, 2006, 6 a.m. to 1 p.m. PST,'' 
March 6, 2008.
     Figure 3. ``Forward Trajectories at 10, 100, & 250 meters, 
Lemoore Area to Bakersfield, September 22, 2006, 6 a.m. to 1 p.m. 
PST,'' March 6, 2008.
     Figure 4. ``Forward Trajectories at 10, 100, & 250 meters, 
Lemoore Area to Corcoran, October 25, 2006, 5 a.m. to 7 a.m. PST,'' 
March 6, 2008.
     Figure 5. ``Forward Trajectories at 250 meters, Lemoore to 
Corcoran to Bakersfield, October 25, 2006, 5 a.m. to 11 a.m. PST,'' 
March 6, 2008.
     Figure 6. ``Forward Trajectories at 10, 100, & 250 meters, 
Lemoore Area to Bakersfield, October 25, 2006, 5 a.m. to 11 a.m. PST,'' 
March 6, 2008.
     Figure 7. ``Annual Peak Day PM10 Concentrations at 
Corcoran,'' March 6, 2008.
     Figure 8. ``Annual Peak Day PM10 Concentrations at 
Bakersfield,'' March 6, 2008.
     Figure 9. ``Annual Peak Day PM10 Concentrations at 
Oildale,'' March 6, 2008.
     Figure 10. ``Annual Peak Fall Day PM10 Concentrations at 
Corcoran (September, October, November Data Only),'' March 6, 2008.
     Figure 11. ``Annual Peak Fall Day PM10 Concentrations at 
Bakersfield (September, October, November Data Only),'' March 6, 2008.
     Figure 12. ``Annual Peak Fall Day PM10 Concentrations at 
Oildale (September, October, November Data Only),'' March 6, 2008.

III. Final Action

    For the reasons set forth in detail in EPA's proposed rule and in 
today's final rule, including the responses to comments, EPA is 
concurring with the State's and the Santa Rosa Rancheria Tribe's 
requests to flag exceedances occurring in 2006 as being caused by 
exceptional events. (i.e., high winds and construction activity in very 
close proximity to the monitor, respectively). In addition, as set 
forth in its proposed rule, EPA is finding that the monitor at the 
Santa Rosa Rancheria was not properly sited for purposes of collecting 
data for comparison to the NAAQS during the period that exceedances 
were monitored in 2006. EPA is thus concluding that the exceedances 
that are the subject of these requests should be excluded from use in 
determining whether the SJV has attained the PM-10 NAAQS. EPA is 
finalizing its proposal to affirm the determination of attainment for 
the SJV, based on quality-assured data through December, 2006.\34\
---------------------------------------------------------------------------

    \34\ The District has flagged exceedances occurring on July 4, 
2007 and January 4, 2008 as being caused by exceptional events. We 
intend to address these exceedances in the future.
---------------------------------------------------------------------------

    For the reasons set forth in its proposed rule and in this final 
rule, EPA is denying the December 29, 2006 petition for reconsideration 
and the March 21, 2007 petition for withdrawal of EPA's 2006 
determination of attainment filed by Earthjustice on behalf of the 
Sierra Club, Latino Issues Forum, and others.

IV. Statutory and Executive Order Reviews

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), this 
action is not a ``significant regulatory action'' and therefore is not 
subject to review by the Office of Management and Budget. For this 
reason, this action is also not subject to Executive Order 13211, 
``Actions Concerning Regulations That Significantly Affect Energy 
Supply, Distribution, or Use'' (66 FR 28355, May 22, 2001). This action 
merely makes a determination based on air quality data, and imposes no 
additional requirements. Accordingly, the Administrator certifies that 
this rule will not have a significant economic impact on a substantial 
number of small entities under the Regulatory Flexibility Act (5 U.S.C. 
601 et seq.). Because this rule does not impose any additional 
enforceable duty, it does not contain any unfunded mandate or 
significantly or uniquely affect small governments, as described in the 
Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4).
    Executive Order 13175 (65 FR 67249, November 9, 2000) requires EPA 
to develop an accountable process to ensure ``meaningful and timely 
input by tribal officials in the development of regulatory policies 
that have tribal implications.'' As discussed in our proposed rule, 
several Indian tribes have reservations located within the boundaries 
of the SJV. EPA is aware of only one tribe in the SJV that operates a 
PM-10 monitor, the Santa Rosa Rancheria. Prior to and since the 
proposed rule, EPA has consulted with representatives of the Santa Rosa 
Rancheria Tribe on the data recorded by its monitor, and the flagging 
of the data, and will continue to work with the Tribe, as provided for 
in Executive Order 13175. Accordingly, EPA has addressed Executive 
Order 13175 to the extent that it applies to this action. This action 
also does not have Federalism implications because it does not have 
substantial direct effects on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government, as 
specified in Executive Order 13132 (64 FR 43255, August 10, 1999). This 
action merely makes a determination based on air quality data and does 
not alter the relationship or the distribution of power and 
responsibilities established in the Clean Air Act. Executive Order 
12898 establishes a Federal policy for incorporating environmental 
justice into Federal agency actions by directing agencies to identify 
and address, as

[[Page 14713]]

appropriate, disproportionately high and adverse human health or 
environmental effects of their programs, policies, and activities on 
minority and low-income populations. Today's action involves 
determinations based on air quality considerations and affirms that the 
SJV attained the PM-10 NAAQS. It will not have disproportionately high 
and adverse effects on any communities in the area, including minority 
and low-income communities.
    This rule also is not subject to Executive Order 13045 ``Protection 
of Children from Environmental Health Risks and Safety Risks'' (62 FR 
19885, April 23, 1997), because it is not economically significant. The 
requirements of section 12(d) of the National Technology Transfer and 
Advancement Act of 1995 (15 U.S.C. 272 note) do not apply because it 
would be inconsistent with applicable law for EPA, when determining the 
attainment status of an area, to use voluntary consensus standards in 
place of promulgated air quality standards and monitoring procedures 
that otherwise satisfy the provisions of the Clean Air. This rule does 
not impose an information collection burden under the provisions of the 
Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.).
    The Congressional Review Act, 5 U.S.C. section 801 et seq., as 
added by the Small Business Regulatory Enforcement Fairness Act of 
1996, generally provides that before a rule may take effect, the agency 
promulgating the rule must submit a rule report, which includes a copy 
of the rule, to each House of the Congress and to the Comptroller 
General of the United States. EPA will submit a report containing this 
rule and other required information to the U.S. Senate, the U.S. House 
of Representatives, and the Comptroller General of the United States 
prior to publication of the rule in the Federal Register. A major rule 
cannot take effect until 60 days after it is published in the Federal 
Register. This action is not a ``major rule'' as defined by 5 U.S.C. 
section 804(2).
    Under section 307(b)(1) of the Clean Air Act, petitions for 
judicial review of this action must be filed in the United States Court 
of Appeals for the appropriate circuit by May 19, 2008. Filing a 
petition for reconsideration by the Administrator of this final rule 
does not affect the finality of this rule for the purposes of judicial 
review nor does it extend the time within which a petition for judicial 
review may be filed, and shall not postpone the effectiveness of such 
rule or action. This action may not be challenged later in proceedings 
to enforce its requirements. (See section 307(b)(2).)

List of Subjects

40 CFR Parts 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Particulate matter, Reporting and recordkeeping 
requirements.

40 CFR Part 81

    Environmental protection, Air pollution control, National parks, 
Wilderness areas.

     Dated March 7, 2008.
Wayne Nastri,
Regional Administrator, Region 9.
 [FR Doc. E8-5188 Filed 3-18-08; 8:45 am]
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