UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX 

75 Hawthorne Street 

San Francisco, CA 94105 

April 18, 2013

Ted Schade

Air Pollution Control Officer

Great Basin Unified Air Pollution Control District

157 Short Street

Bishop, California 93514

Dear Mr. Schade:

Thank you for your submission of the Great Basin Unified Air Pollution Control District’s 

(GBUAPCD’s) 2012 Ambient Air Monitoring Network Plan in June 2012. Based on the 

information provided in the plan, EPA approves all portions of the network plan except those 

specifically identified below. 

Annual network plans are important documents for regulatory purposes (e.g., State 

Implementation Plans, designations and redesignations) and public information, in addition to 

the myriad uses by the air districts. EPA is revising the review process for annual network plans 

to specifically check and document the comprehensive set of items that are required to be 

included in the annual network plans per 40 CFR 58.10 in a consistent manner. We have created 

a checklist that lists all these items and have included it as Attachment A. While the items in the 

checklist are required by EPA regulations, we acknowledge that we have not specifically 

requested some of this information in previous annual network plan reviews. We recognize that 

your plan may not have all the items that we have currently identified and hope to work with you 

on the inclusion of these items in future plans. To facilitate these changes, EPA has provided 

detailed feedback in the checklist where information should be included or revised in next year’s 

plan.

Please note that we cannot approve portions of the annual network plan for which the 

information in the plan is insufficient to judge whether the requirement has been met, or for 

which the information, as described, does not meet the requirements as specified in 40 CFR 

58.10 and the associated appendices. EPA Region 9 also cannot approve portions of the plan for 

which the EPA Administrator has approval authority. Accordingly, we are not acting on the 

specific portions of your agency’s annual network plan listed in Attachment B.

All of the comments in Attachments A, B, and C should be addressed in next year’s network 

plan. Also, GBUAPCD received comments from the Los Angeles Department of Water and 

Power (LADWP) on specific portions the annual network plan during the public comment 

period. GBUAPCD’s responses to these comments were included with the network plan 
submittal. EPA also received separate comments on the annual network plan outside of the 

comment period. EPA has determined that GBUAPCD’s responses to the substantive comments

are adequate and has provided supplemental responses to the substantive comments in

Attachment D. If you have any questions regarding this letter or the enclosed comments, please 

feel free to contact me at (415) 972-3851 or Michael Flagg at (415) 972-3372.

Sincerely,

/s/

Matthew Lakin, Manager

Air Quality Analysis Office

Enclosures:

A. Annual Air Monitoring Network Plan Checklist

B. Elements where EPA is Not Taking Action

C. Additional Detailed Comments

D. Response to Comments

cc: Christopher Lanane, GBUAPCD

Karen Magliano, CARB
Attachment B: Annual Air Monitoring Network Plan Items where EPA is Not Taking 

Action

We are not acting on the portions of annual network plans where either EPA Region 9 lacks the 

authority to approve specific items of the plan, or EPA has determined that a requirement is 

either not met or information in the plan is insufficient to judge whether the requirement has 

been met.

 NCore monitoring requires EPA Administrator approval. Per 40 CFR 58.11(c), NCore 

network design and changes are subject to approval of the EPA Administrator. 

Therefore, we are not acting on these items.

 System modifications (e.g., site closures or moves) are subject to approval per 40 

CFR58.14(c). Information provided in the plan was insufficient for EPA to approve the

following system modification listed in the plan per the applicable requirement: 

relocation of the Flat Rock PM10 SLAMS site. Therefore, we are not taking

action on this item as part of this year’s annual network plan.

 EPA identified items in you agency’s annual network plan where a requirement was not 

being met or information in the plan was insufficient to judge whether the requirement 

was being met based on 40 CFR 58.10 and the associated appendices. Therefore, we are 

not acting on of the following items:
Item Checklist Row

(Attachment A) Issue

Distance to roadway 62 Insufficient information to judge

Traffic count 63 Insufficient information to judge

Scale of representation 16 Insufficient information to judge

Distance between collocated 

monitors

33 Insufficient information to judge

Distance from supporting 

structure

66 Insufficient information to judge

PM2.5 monitors represent 

community wide air quality at 

neighborhood scale

54 Insufficient information to judge

Population-oriented PM2.5 site 

in area of expected max 

concentration

55 Insufficient information to judge

PM2.5 background/transport 

site 

58 Insufficient information to judge

Document how agency will 

provide for the review of 

changes to PM2.5 network

22 Insufficient information to judge

Precision and accuracy reports 23 Insufficient information to judge

Data certification 24 Insufficient information to judge

Parameter occurrence code 43 Insufficient information to judge

Sampling and analysis method 13 Insufficient information to judge in some 

instances

Method code 37 Insufficient information to judge in some 

instances

Monitor start date 38 Insufficient information to judge

Monitor type 39 Insufficient information to judge

Monitoring objective 40 Insufficient information to judge

Parameter code 42 Insufficient information to judge

Statement of purpose 2 Insufficient information to judge

NCore site information 7 Insufficient information to judge

Frequency of 1-pt QC checks 28 Insufficient information to judge

Date of annual PE audits 29 Insufficient information to judge

Probe material 72 Insufficient information to judge

Residence time 73 Insufficient information to judge

Additional information for each of these items is in included in Attachment A.
Attachment C: Additional Detailed Comments

 The Coso Junction PM10 site is characterized as “regional scale” on p.7, but listed as 

“neighborhood” in the site report in Appendix A. Therefore, please correct this 

discrepancy in next year’s plan. 

 While some of the dates for PM10 semi-annual flow audits are missing from the Appendix 

A site reports, EPA has reviewed information provided by the district and has confirmed 

that this requirement is currently being met. Please provide the dates of the semi-annual 

flow audits for each monitor in next year’s plan.

 The PM10 monitors in the network are currently monitoring at the correct frequency, but 

information included in the plan is unclear. Please provide the specific operating 

schedules for each monitor in next year’s plan. 

 While the collocation requirement for manual PM10 monitors is currently being met, 

please include more detailed information concerning the PM10 collocation requirement 

and specific information on the operating schedules for manual PM10 monitors at the 

Keeler site. 
Attachment D: Response to Comments

The Los Angeles Department of Water and Power (LADWP) submitted comments to the Great 

Basin Unified Air Pollution Control District (GBUAPCD) on May 16, 2012, during the comment 

period held by GBUAPCD on its proposed 2012 annual network plan (2012 ANP). GBUACPD 

responded to these comments in a memorandum dated May 23, 2012, which was included with 

the final 2012 ANP submitted to EPA on June 29, 2012. LADWP subsequently sent a letter to 

EPA on September 28, 2012 expanding upon the comments made in the May 16, 2012 letter, and 

providing responses to GBUAPCD’s responses in the May 23, 2012 memorandum. LADWP sent 

further comments on January 8, 2013 supplementing their comments submitted on September 28, 

2012.

Comment: LADWP acknowledges that GBUAPCD’s state or local air monitoring stations 

(SLAMS)1network is covered under an approved California Air Resources Board (ARB) 

Quality Assurance Plan (QAP). However, LADWP contends that the ARB QAP does not cover 

the use of the data used to identify supplemental dust control areas on Owens Lake because the 

ARB QAP does not properly assure quality for all the instrument systems that are used in the 

dust source identification process. LADWP also notes that some of the instrument system 

elements that are not covered by the QAP (e.g. sand motion monitoring and video monitoring) 

are described in the 2012 ANP. LADWP also requests that GBUAPCD update its PM10 and 

PM2.5 Quality Assurance Project Plans (QAPPs) for particulate matter with an aerodynamic 

diameter less than or equal to a nominal 10 micrometers (PM10) and particulate matter with an 

aerodynamic diameter less than or equal to a nominal 2.5 micrometers (PM2.5) to include all of 

the instrument systems that are required to implement the procedures described in the 2008 

Owens Valley State Implementation Plan (2008 SIP), and have those QAPPs approved in a 

public proceeding. 

Response: The requirements contained in 40 CFR Part 58 Appendix A, including the 

requirements for QAPPs, are applicable to SLAMS air monitoring data and Prevention of 

Significant Deterioration (PSD) data.2These requirements also apply to all special purpose 

monitor (SPM)3stations using a federal reference method (FRM), a federal equivalent method 

(FEM), or an approved regional method (ARM), which meets the requirements of 40 CFR Part 

58 Appendix E.4LADWP’s initial comments on the 2012 ANP and their subsequent September 

28, 2012 letter both acknowledge that the GBUACPD’s SLAMS network is covered by ARB’s 

QAP. As the additional instrument systems mentioned by LADWP in their comments are not 

SLAMS and do not use FRM, FEM or ARM methods, information pertaining to the operation of 

 

1

“The SLAMS make up the ambient air quality monitoring sites that are primarily needed for NAAQS comparisons, but may 

serve other data purposes. SLAMS exclude special purpose monitor (SPM) stations and include NCore, PAMS, and all other 

State or locally operated stations that have not been designated as SPM stations.” 40 CFR 58.1.

2

40 CFR 58.11(a)(1); 40 CFR Part 58, Appendix A, § 1. 

3

“An SPM is defined as any monitor included in an agency's monitoring network that the agency has designated as a special

purpose monitor in its annual monitoring network plan and in AQS, and which the agency does not count when showing 

compliance with the minimum requirements of this subpart for the number and siting of monitors of various types.” 40 CFR 

58.20(a). 

4

40 CFR 58.20(b); 40 CFR Part 58, Appendix A, § 1. 
those instruments and the subsequent data use in the dust source identification process is not 

required to be included in QAPPs under 40 CFR 58 Appendix A. Furthermore, there are no 

requirements that QAPPs must undergo a public review process prior to submission and approval 

by EPA or the PQAO (primary quality assurance organization).

Comment: The current GBUAPCD monitoring network design is problematic because it focuses 

on Owens Lake and does not adequately assess contributions from other source areas. LAWDP 

also requests that GBUAPCD identify the major off-lake source areas and monitor them for both 

sand motion and dust emissions. 

Response: Comments concerning which sources are influencing specific monitors are beyond 

the scope of what EPA is required to review and approve as part of the annual network plan 

process. Generally, ambient air monitoring network design is performed by the State or local air 

districts and there are no specific requirements in 40 CFR Part 58 Appendix D, 4.6 that mandate 

a PM10 network capture influences from specific sources. Currently, the PM10 network in the 

Owens Lake nonattainment area meets the applicable requirements in 40 CFR 58 Appendix D. 

Comment: The Keeler PM2.5 and PM10 monitors, and the North Beach PM10 monitor appear to 

violate the EPA siting criteria contained in 40 CFR Part 58 Appendix E, §3(a) due to their close 

proximity to a number of unpaved roads. 

Response: As explained in 40 CFR 58 Appendix E, §3(a), it is important to understand the 

monitoring objective for a particular location in order to interpret the requirement for spacing 

from minor sources. The Keeler and North Beach monitoring sites are characterized as having 

population oriented5(population exposure) and source impact (source oriented) site types, 

respectively.640 CFR 58 Appendix E, §3(a) explains that if the objective for a monitoring site is 

to investigate local PM10 sources, then the site is likely to be properly located nearby. 

Furthermore, in these instances, capturing the influence of emissions from nearby unpaved roads 

may be important, and moving these monitors away from such sources may underestimate the 

population’s exposure to harmful levels of PM10 and PM2.5. Due to the monitoring objectives of 

these sites and their distance from roadways, the presence of nearby unpaved roads does not 

violate EPA’s siting criteria in 40 CFR 58 Appendix E.

Comment: The 2012 ANP does not adequately explain the April 2011 discontinuation and 

relocation of the Flat Rock PM10 monitor to the Mill Site.

 

Response: EPA agrees that there was insufficient information included in the 2012 ANP 

concerning the shutdown and relocation of the Flat Rock PM10 monitor. System modifications to 

the SLAMS network must meet specific criteria outlined in 40 CFR 58.14 and be subsequently 

approved by EPA. As there was not enough information to judge whether the shutdown and 

relocation of the Flat Rock monitor was appropriate, EPA is not taking action at this time on the 

 

5 Population-oriented monitoring (or sites) means residential areas, commercial areas, recreational areas, industrial areas where 

workers from more than one company are located, and other areas where a substantial number of people may spend a significant 

fraction of their day.

6

2012 ANP, Table 2.
modification and will work closely with GBUAPCD to appropriately document the shutdown 

and relocation. 

Comment: The 2012 ANP does not provide documentation that siting issues at the Coso Junction 

monitoring site have been corrected and data from the site cannot be used to assess the 

contributions from Owens Lake.

Response: While the documentation of the siting issue at Coso Junction was discussed in 75 FR 

54031 and in subsequent correspondence, EPA agrees that the ANP should contain a statement that 

describes the actions taken to address previously identified siting issues at the Coso Junction 

monitoring site. In regards to the data, an assessment of whether the data from a specific monitor 

is influenced by a particular source is beyond the scope of what EPA is required to review and 

approve as part of the annual network plan process. Generally, ambient air monitoring network 

design is performed by the State or local air districts and there are no specific requirements in 40 

CFR Part 58 Appendix D, 4.6 that mandate a PM10 network capture influences from specific 

sources. In the 2012 ANP, the Coso Junction is appropriately characterized as a population 

oriented (population exposure) and pollutant transport (regional transport) regional scale 

monitoring site. 

Comment: Information concerning the proposed new locations of the T-4 and T-23 nonregulatory SPMs is not included in the 2012 ANP.

Response: As described in the 2012 ANP and GBUACPD’s responses to LADWP’s comments, 

the T-4 and T-23 monitors are non-regulatory special purpose monitors that are being used to 

measure PM10 emissions near the remaining source areas on the lakebed and to further refine the 

District’s Dust Identification Program model. As these monitors are only being used in shortterm special studies, EPA generally does not require information for such monitors to be 

included as part of the ANP. Furthermore, while EPA approval is required for addition and 

discontinuation of SLAMS, no such approval is required for changes in SPM stations.7

Comment: EPA cannot approve the 2012 network plan, because it includes monitors that are no 

longer part of GBUACPD’s network as a result of LADWP’s termination of the Dirty Socks, 

Mill Site, and North Beach monitor licenses. GBUACPD must withdraw the current 2012 

Network Plan from EPA and amend the plan to remove these monitoring stations from its 

network. 

Response: GBUAPCD is not required to withdraw and resubmit the 2012 ANP due to changes in 

the network after submittal to EPA. The shutdown of the Dirty Socks, Mill Site, and North 

Beach PM10 monitors were not approved by EPA in accordance with 40 CFR 58.14. ANPs are 

the appropriate mechanism to document changes to the network. EPA expects that information 

pertaining to the shutdown of these monitors will be included in future ANPs. 

 

7

40 CFR 58.10(e), 58.11(c).