April 21, 1997
Office of Air Management
Indiana Department of Environmental Management
100 North Senate Avenue
P.O. Box 6015
Indianapolis, Indiana 46206-6015
Dear Ms. George:
This letter is in response to the Network Review package describing the 1997 air monitoring
network plans for Indiana completed by your staff December 17, 1996, and submitted to my
staff for review. My staff has completed discussions of your proposal internally, with members
of your staff and with appropriate staff at the Office of Air Quality Planning and Standards
One significant change in current plans from those described in the proposal has come to light.
The Vermillion County PM10 monitoring site which was planned for discontinuation continues
to operate. In view of the fact that the area represented by this site is currently classified as
non-attainment, this is a positive change from the proposal. Air quality readings from the site,
however, show low levels of pollution over the past several years. U.S. Environmental
Protection Agency (USEPA) looks forward to working with Indiana to process a redesignation
request and evaluating the feasibility of discontinuing monitoring at this site.
There are a number of proposed changes to the National Air Monitoring Stations (NAMS)
network throughout the State of Indiana. Two NAMS sulfur dioxide (SO2) monitors and the two
NAMS lead (Pb) monitors in Indianapolis are proposed to be discontinued. In addition, the
NAMS SO2 and PM10 monitors at the Gary Federal Building are proposed to be relocated to
the Gary IITRI monitoring site while the NAMS PM10 monitor at the Field School is proposed
to be relocated to an unspecified site.
The proposed discontinuation of the NAMS SO2 and Pb sites in Indianapolis is approved. The
only complication is that current regulations require the operation of the two lead sites. Region
5 and OAQPS agree, however, that the value of these two sites is very low. OAQPS has
informed Region 5 there will be pending changes to the lead monitoring regulations which
would remove the regulatory requirement for these two sites and, therefore, is agreeing with
Region 5 in the approval of the discontinuation of these sites at this time.
The USEPA is also comfortable with the proposed relocations of the NAMS PM10 monitor at
the Field School and the NAMS PM10 and SO2 monitor at the Gary Federal building. Indiana
should submit an application for approval of the new sites as soon as possible for the USEPA
Indianapolis also proposed to reduce the sampling frequency of the PM10 monitor at site
18-097-0071 from every other day to every sixth day. The monitored concentrations at this site
support this decision and the USEPA approves of the change in sampling frequency.
The proposal to end carbon monoxide (CO) sampling in St. Joseph County is also approved.
Historical data and local population indicate sampling for CO is no longer needed in the South
We would like to commend Indiana for three positive developments in the ozone monitoring
networks. The new monitor installed in Posey County and the one proposed for LaPorte will
provide valuable data for assessing the ozone air quality in areas whose current status is
currently under discussion. The location of an ozone monitor further upwind of Indianapolis
should also provide some valuable background data for this site.
The monitoring network proposal identifies the location of the LaPorte monitor as housing a
water treatment plant. Experience has shown that placing ozone monitors at water treatment
plants which use ozone to treat the water may interfere with obtaining valid data. The USEPA
requests that Indiana identify whether or not the water treatment plant at this site uses ozone in
its process and, if so, consider a different location for the monitor.
The USEPA would like to encourage the establishment of air toxicant monitoring sites in
Indiana. However, we are not in a position at this point to comment on whether or not additional
support from 105 grant money would be available to support this effort. Since Indiana is
currently participating in the National Environmental Performance Partnership (NEPPS)/
Performance Partnership Grant system, funds can be redirected to environmental priorities
regardless of the underlying media grant constraints. Thus, if the State wishes to pursue air
toxicant monitoring as such a priority, the USEPA would like to cooperate by modifying either
the Fiscal Year 1997 or Fiscal Year 1998 grants to allow this important activity to be
We are also pleased to note Indiana's desire to conduct sampling for mercury. We note,
however, that the methodology proposed is designed only to collect particulate phase mercury
which remains on high volume particulate filters. A significant portion of the mercury in the air is
often in the vapor phase and even much of that in the particulate phase can be lost during the
particulate collection process. A standard USEPA methodology for collecting ambient mercury
data is expected to be published imminently. The USEPA would be glad to help Indiana
evaluate this methodology as a preferred means for collecting mercury data.
Overall, the USEPA is pleased with the air quality monitoring networks proposed by Indiana for
1997. The USEPA is therefore giving full approval to Indiana's 1997 air monitoring network
under the provisions of 40 CFR Part 58 25. With the possible changes to the air quality
monitoring networks which would be necessary under the proposed changes to air quality and
monitoring regulations for ozone and particulate matter, revisions of the air quality monitoring
networks for 1998 will be quite challenging. We look forward to discussing these issues with
Indiana in the near future.
The USEPA would like to express appreciation for the format of Indiana Network Review
package. Dividing the network proposal into status areas by pollutant made reviewing the
quality of the network for each status area much easier for my staff. I know that putting the
submittal into this format was a significant effort for your staff so I wanted to let you know that
the effort contributed greatly to the utility of the document.
Thank you for the chance to review the 1997 air quality monitoring network plans for the State
of Indiana and for the City of Indianapolis. If you have questions or comments on our review,
please contact William Damico, of my staff, at (312) 353-8207 or by e-mail at
Stephen Rothblatt, Chief
Air Programs Branch
Richard D. Zeiler, Chief
Air Monitoring Branch
Aaron Childs, Program Manager/Monitoring
Environmental Services and Planning Section
Environmental Resources Management Division
City of Indianapolis
David Lutz, NAMS Coordinator
Office of Air Quality Planning and Standards
For further information, contact:
This Information Last Modified On:
09/18/2008 03:58 PM