CASTNET 2017 Annual Network Plan
Response to Comments

Clean Air Markets Division
Office of Atmospheric Programs
US Environmental Protection Agency

June 21, 2017


-------
Table of Contents

1.	US EPA Region 6	3

2.	US EPA Region 10	4

3.	Wyoming DEQ	5

Page 2 of 5


-------
1. Comment in regard to the CASTNET site Chaco Culture National Historical Park, NM (CHC432).

Commenter: Mark Sather, EPA Region 6.

Date received: April 27, 2017

Comment 1. I was wondering if the Chaco Culture National Historical Park in New Mexico site now has
an AQS number that could be included in the plan.

Response 1. The Chaco Culture National Historical Park in New Mexico site has an AQS ID of 35-045-
0020. The plan has been updated to include this AQS ID.

Page 3 of 5


-------
2. Comments in regard to the CASTNET site Denali National Park (DEN431).

Commenter: Chris Hall, US EPA Region 10.

Date received: May 8, 2017

Comment 1. Why is the NAAQS monitoring objective for the Denali site 02-068-0003 listed as
unknown ? This is the only site in the network with this designation. I would suggest it be changed to
General/Background.

Response 1. Denali National Park's CASTNET ozone monitor has been updated in both the plan and in
AQSto "General/Background."

Comment 2. Appendix C graph of the monitoring seasons should include Alaska. Their season is Apr-Oct
which is not listed in the legend.

Response 2. The ozone season map in Appendix C has been updated to include Alaska and an "April to
October" season is included inside the legend.

Page 4 of 5


-------
3. Comments in regard to the revised Exceptional Events Rule and the monitoring spatial scale
used at the collocated CASTNET sites at Rocky Mountain National Park (ROM406/ROM206).

Commenter: Daniel Sharon, Air Quality Monitoring Project Manager. Wyoming DEQ.

Date received: May 30 & 31, 2017

Comment 1. The Wyoming Air Quality Division (AQD) has one comment on the 2017 CASTNet Annual
Network Plan. Section 3 of the plan discusses Exceptional Events. While it is noted that federal agencies
are now able to submit EE Demonstrations under the new Exceptional Events Rule, it is unclear how
CASTNet plans to approach future potential EEs at network sites. For example¦, does CASTNet plan to
take the lead in the development of demonstrations, with guidance and support from the applicable
state agency? The Wyoming AQD respectfully requests that clarification be added to the 2017 Network
Plan about the process CASTNet intends to follow for the development of EE Demonstrations following
the initial data flagging process, including a discussion of State/Federal responsibilities in this process.
Please let me know if you have any questions regarding this comment.

Response 1. As noted in the preamble to the 2016 Exceptional Events Rule (81 FR 68216, 10/3/2016),
"as the single actor responsible for administering air quality planning and management activities within
its jurisdictional boundaries, the state, exclusive of tribal lands, is ultimately responsible for submitting
exceptional event demonstrations for exceedances that occur at all regulatory monitoring sites within
the boundary of the state." CASTNET federal partners will continue to work with S/L/T air agencies to
flag ambient data potentially influenced by an exceptional event as requested by a state, local, or tribal
(S/L/T) air agency that has jurisdiction over the area where a CASTNET site is located and assist in
preparing a demonstration (i.e., providing relevant information) if requested by a S/L/T agency. State
agencies will continue to be responsible for working with the EPA region to submit exceptional event
demonstrations, which may include data from CASTNET sites. S/L/T agencies should follow the
regulations described in the revision to 40 CFR Parts 50 and 51, Treatment of Data Influenced by
Exceptional Events (81 FR 68216, 10/3/2016) to prepare and submit exceptional event demonstrations.

Comment 2. Since sending you Wyoming's comment on the CASTNet 2017 Network Plan, our group
noticed something else we'd like to comment on. Pages 26 and 27 of the Plan provide the site
information for the Rocky Mountain National Park stations (08-069-0007, primary and 08-069-9991,
collocated). According to the description, these monitors are located within 7.5 meters of each other, yet
the spatial scales listed are different between the two monitors. The spatial scale for the primary monitor
is "Neighborhood" while the scale for the collocated monitor is "Regional Scale." The Wyoming AQD
would expect stations located this close to each other to have the same measurement scale. Please let
me know if you have any questions regarding this comment.

Response 2. The National Park Service has updated the spatial scale at the Rocky Mountain National
Park (08-069-0007) to "Regional Scale" in both the plan and in AQS.

Page 5 of 5


-------