April
14,
2004
Response
to
Ozone
Air
Monitoring
Issues
Raised
by
Rochester
Metropolitan
Area
Officials
John
Filippelli,
Chief
/
s/
State
Implementation
Plan
Section,
DEPP­
APB
Raymond
Werner,
Chief
Air
Programs
Branch
This
is
in
response
to
concerns
about
the
siting
of
the
two
Rochester
metropolitan
ozone
air
quality
monitors
raised
by
city
and
county
elected
officials
in
a
March
15,
2004
letter
to
the
Regional
Administrator
and
in
other
discussions
and
forums.
Many
of
these
concerns
were
reiterated
and
expanded
upon
during
our
April
7,
2004
conference
call,
chaired
by
the
Deputy
Regional
Administrator
with
Rochester
area
officials.
The
following
point­
by­
point
response
is
based
on
several
documents
and
other
sources
of
information,
including:

°
August
6,
2002,
internal
New
York
State
Department
of
Environmental
Conservation
(
NYSDEC)
concerning
the
Williamson
ozone
monitor.
(
Copy
attached.)

°
August
7,
2003,
field
audits
conducted
by
DESA's
Monitoring
and
Assessment
Branch
(
MAB),
and
the
subsequent
audit
reports.

°
My
August
7,
2003,
site
visit
to
the
Rochester
area
monitoring
sites
and
photographs
taken
that
day.

°
March
30,
2004
conference
call
between
representatives
of
NYSDEC's
Bureau
of
Air
Quality
Surveillance,
MAB,
and
the
State
Implementation
Plan
Section.

°
Information
from
MAB's
files
about
the
sites.

°
40CFR
Part
58
­
Ambient
Air
Quality
Surveillance.

Horizontal
and
Vertical
Placement
Concern:
The
Williamson
station
is
less
that
one
meter
from
support
structures
and
the
roof
of
the
building,
and
therefore
does
not
meet
EPA
siting
criteria.

Response:
The
distance
from
the
probe
inlet
to
the
building
and
the
roof
1.12
meters
above
the
roof.
This
is
the
closest
part
of
the
structure
to
the
probe.
Thus
the
site
meets
this
siting
criteria.
Spacing
from
Minor
Sources
Concern:
The
Rochester
monitor
is
located
adjacent
to
a
power
substation
that
produces
ozone.

Response:
The
siting
regulations
at
40CFR
Part
58
do
not
recognize
proximity
to
power
substations
as
a
reason
to
invalidate
air
monitoring
data
as
hypothesized
by
the
commentor.
However,
to
more
fully
address
this
concern,
we
contacted
air
monitoring
experts
at
EPA's
Office
of
Air
Quality
Planning
and
Standards
(
OAQPS)
and
Office
of
Research
and
Development;
they
did
not
identify
substations
as
a
source
of
interference
with
ozone
measurement.
They
were
also
not
aware
of
this
being
identified
as
an
issue
in
the
technical
literature
concerning
ozone
monitoring.
Additionally,
NYSDEC
and
OAQPS
do
not
believe
that
a
substation
would
generate
significant
amounts
of
ozone
unless
it
is
arcing,
which
would
cause
an
immediate
operations
and
safety
concern
for
the
utility.
Finally,
there
is
a
parking
area,
a
small
grassy
patch
and
half
the
length
of
the
trailer
between
the
monitor
probe
and
the
substation.
The
distance
appears
to
be
at
least
20
meters
and
not
immediately
adjacent
to
the
monitor.
This
would
appear
to
be
far
enough
to
mitigate
any
interference
that
the
substation
might
be
likely
to
cause.

Concern:
The
Williamson
station
(
and
its
probe)
is
located
adjacent
to
an
area
where
buses
are
often
parked
and
have
been
seen
idling.

Response:
EPA's
siting
criteria
is
satisfied.
There
is
a
school
bus
parking
lot
about
30
meters
from
the
probe.
This
lot
handles
a
few
dozen
buses.
EPA's
siting
criteria
(
40CFR
Part
58,
Appendix
E,
Table
1)
establishes
minimum
separation
distances
between
roadways
and
monitor
probes.
For
roadways
with
average
daily
traffic
of
less
that
10,000
vehicles
per
day
the
minimum
distance
is
10
meters.
While
we
do
not
have
exact
traffic
counts
for
the
parking
lot,
based
on
the
number
vehicles
that
park,
traffic
levels
or
more
than
10,000
vehicles
per
day
are
inconceivable.
Moreover,
very
little
school
bus
activity
has
been
observed
in
this
lot
during
the
peak
summer
ozone
season,
which
is
consistent
with
our
discussions
with
school
bus
operators
as
part
of
the
Clean
School
Bus
USA
project.

Spacing
from
Obstructions
and
Trees
Concern:
The
Williamson
station's
probe
was
within
eight
meters
of
the
drip
line
of
trees.
The
probe
should
be
located
20
meters
or
more
from
the
trees,
given
the
height
of
the
trees.
A
sampling
stations
having
a
probe
located
closer
to
an
obstacle
than
the
criteria
allows
should
be
classified
as
middle
scale
rather
that
neighborhood
or
urban
scale.

Response:
As
noted
in
40CFR
Part
58,
Appendix
E,
Section
2.4,
there
"
should"
be
a
20
meter
or
more
separation
from
the
drip
line
of
trees,
primarily
because
trees
have
a
"
scavenging"
effect
on
ozone
(
i.
e.,
trees
in
the
vicinity
of
ozone
monitors
tend
to
reduce
ozone
readings).
As
noted
in
NYSDEC's
August
6,
2002
memo,
"
The
site
at
Williamson
meets
all
EPA
siting
criteria
with
the
marginal
exception
of
distance
to
trees."
NYSDEC
goes
on
to
state
that
"
this
would
result
in
the
instrument
reading
lower."
NYSDEC
has
since
reported
that
the
trees
in
question
were
removed
in
September
2002
well
before
the
start
of
the
2003
ozone
season.
Moreover,
consistent
with
Section
2.3,
there
is
(
and
was
before
September
2002)
a
270
degree
unrestricted
airflow
around
the
monitor
inlet
which
further
negates
any
impact
from
trees.
Accordingly,
this
site
can
appropriately
considered
a
neighborhood
or
urban
scale
site.

Concern:
The
Rochester
site
is
impermissibly
close
to
trees
and
buildings,
and
does
not
meet
the
270
degree
rule.

Response:
There
are
numerous
trees
close
the
Rochester
probe.
As
previously
noted
this
would
tend
to
lower
ozone
readings.
The
buildings
near
the
Rochester
site
are
primarily
one
and
two
family
homes
whose
backyards
abut
the
parcel
on
which
the
Rochester
trailer
is
located.
This
would
not
appear
to
be
significantly
affecting
ozone
readings
at
the
site.

Spacing
form
Roadways
Concern:
The
Rochester
Station
was
located
very
near
the
intersection
of
Farmington
Road
and
Wyand
Crescent,
and
therefore
was
in
violation
of
the
spacing
from
roadways
requirements.

Response:
Based
on
our
discussions
with
NYSDEC
and
a
review
of
EPA
site
records,
the
monitor
meets
siting
criteria
in
terms
of
minimum
separation
from
roadways.
Farmington
Road
has
a
traffic
volume
of
about
1,000
vehicles
per
day
and
is
about
40
meters
from
the
site.
Wyand
Crescent
has
a
traffic
volume
of
4,000
vehicles
per
day
and
is
about
35
meters
from
the
site.
EPA's
siting
criteria
(
40CFR
Part
58,
Appendix
E,
Table
1)
specify
a
minimum
separation
of
10
meters
from
roadways
having
traffic
volumes
of
less
than
10,000
vehicles
per
day.

Downwind
Distance
from
the
City
to
be
Measured
Concern:
The
Williamson
station
is
classified
as
being
an
urban
scale
monitoring
station.
A
station
designed
to
measure
ozone
and
its
precursors
produced
in
a
particular
city
must
be
five
to
seven
hours
downwind
of
the
city
it
is
intended
to
measure.
Based
National
Weather
Service
data
a
station
needs
to
be
50
to
100
miles
west
southwest
(
they
probably
mean
east
southeast,
prevailing
summer
winds
in
Rochester
are
from
the
west,
southwest,
and
west
northwest)
of
the
City
of
Rochester.
The
Williamson
monitor
is
approximated
23
miles
downwind.
Therefore,
the
resulting
data
cannot
be
used
to
determine
the
Rochester
MSA's
compliance
with
the
8­
hour
ozone
NAAQS.

Response:
The
Williamson
monitor
is,
in
fact,
recording
violations
of
the
ozone
standard
downwnd
of
the
Rochester
urban
center.
Monitors
of
this
type
are
appropriate
for
measuring
ozone
concentrations
in
the
metropolitan
area.
Specifically,
Part
58
allows
for
the
use
of
urban,
neighborhood,
and
middle
scale
monitoring
data
to
determine
if
an
area
is
violating
the
ozone
standard.
While
the
distance
issue
cited
above
suggests
that
another
location
further
downwind
may
have
even
higher
ozone
readings,
the
readings
at
the
Williamson
monitor
indicate
that
residents
of
this
area
are
subject
to
violations
of
the
health­
based
8­
hour
ozone
standard.
This
is
an
appropriate
basis
for
a
nonattaiment
designation
of
the
Rochester
area.
Additionally,
trajectory
analysis
indicates
that
the
Rochester
metropolitan
area
contributes
to
ozone
violations
in
Jefferson
County,
New
York,
which
is
approximately
100
miles
away
from
the
Rochester
metropolitan
area.

Conclusion
The
Williamson
site
meets
EPA
siting
criteria.
There
was
a
minor
concern
about
trees,
but
this
would
have
only
served
to
lower
ozone
readings.
Moreover,
the
trees
were
removed
well
before
the
2003
ozone
season.
Finally,
based
on
the
fact
that
the
monitor
meets
siting
criteria
and
has
ozone
readings
consistent
with
other
sites
in
the
Great
Lakes
region,
we
believe
the
Williamson
site
accurately
represents
ozone
air
quality
in
the
Rochester
metropolitan
area.

The
Rochester
site
does
not
meet
EPA
siting
criteria
because
of
its
proximity
to
trees.
As
noted,
this
would
lower
ozone
readings
at
the
site.
Even
so,
the
monitor
is
recording
violations
for
the
health­
based
air
quality
standard
for
ozone.
With
this
in
mind,
EPA
concludes
that
ozone
data
being
recorded
at
the
Rochester
site
is
also
representative
of
air
quality
conditions
in
the
Rochester
metropolitan
area.

Attachment
cc:
K.
Callahan,
DRA
W.
Mugdan,
DEPP
R.
Borsellino,
DEPP
W.
Baker,
DEPP
R.
Kelly,
DEPP­
APB
