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**MEMORANDUM**

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  **To:**        NETAC Technical Advisory Committee

  **From:**      Greg Yarwood

  **Date:**      September 17, 2004

  **Subject:**   2007 Ozone Reductions for NETAC Control Strategies 1 and 2
  -------------- ------------------------------------------------------------

In March 2004, NETAC submitted to EPA a Clean Air Action Plan (CAAP) for
Northeast Texas that demonstrated attainment of the 8-hour ozone
standard based on control measures that are currently enforceable
(NETAC, 2004). The projected 2007 8-hour ozone design values for the
NETAC attainment demonstration are shown in Table 1.

-   Note that the Waskom and Karnack 2007 DVs in Table 1 are different
    from Table 6-5 of the CAAP because computational errors have been
    corrected.

**Table 1**. Projected 2007 8-hour ozone design values (ppb) for the
CAAP attainment demonstration scenario (NETAC, 2004).

  ------------------------- --------------- --------------- ---------------
  Monitor                   2001-2003 DV    Modeled RRF     Scaled 2007 DV

  Longview                  82              0.981           80

  Tyler                     81              0.954           77

  Karnack                   84              0.958           80

  Waskom                    84              0.966           81
  ------------------------- --------------- --------------- ---------------

Notes: The Longview and Tyler monitors have 2001-2003 DVs.

The Karnack and Waskom monitors have 2002-2003 DVs.

**CONTROL STRATEGIES**

At the request of TCEQ and EPA, NETAC has modeled two additional sets of
control strategies that go beyond the 2007 base case (run 07base5) which
constituted NETAC's attainment demonstration. The control strategy runs
show additional reductions in ozone below the levels in the 2007 base
case run. Since the 2007 base case demonstrates attainment of the 8-hour
ozone standard, these control strategies provide an additional measure
of safety in 8-hour ozone levels for Northeast Texas.

The control strategies modeled by NETAC are:

-   **CTL01**: Add HRVOC reductions at Longview. Add the "gas can" rule.
    Remove the water heater NOx rule.

-   **CTL02**: Add 1.5 tons/day of TERP NOx reductions in the NETAC 5
    County area to Control Strategy 1.

The elements of these strategy runs are explained below.

**HRVOC Reductions at Longview**

The CAAP identified additional local emissions reductions beyond the
measures accounted for in the attainment demonstration (07base5). These
reductions include enforceable reductions of highly reactive VOC (HRVOC)
emissions from the Eastman and Huntsman chemical facilities near
Longview, Texas. As described on page 6-11 of the CAAP (NETAC, 2004),
these reductions amount to 0.86 tons/day at Eastman and 0.08 tons/day
(29 tons/year) at Huntsman by the start of the 2007 ozone season. These
reductions will be enforceable through emissions permits listed in the
CAAP.

**TERP NOx Reductions**

TCEQ estimates that the Texas Emissions Reduction Program (TERP) will
result in a 1.5 ton/day reduction in NOx reductions from off-road mobile
sources in the NETAC 5 County area in 2007 (TCEQ, 2007).

**TCEQ "Water Heater" NOx Rule**

The 2007 base case included reductions in NOx emissions from industrial
water heaters, small boilers and process heaters (TAC 117.460-469). TCEQ
estimated that this rule would reduce NOx emissions by 0.5 tons/day in
the 95-county East/Central Texas region. Eliminating this rule increased
2007 NOx emissions in the NETAC 5 county area by 0.05 tons/day, which is
a negligible amount.

**TCEQ "Gas Can" VOC Rule**

The TCEQ has proposed a statewide low emission "gas can" rule to reduce
VOC emissions from small containers used to store gasoline. The
estimated benefits of this rule in the NETAC area are small because the
VOC emissions inventory is dominated by biogenic emissions (NETAC,
2004).

**CONTROL STRATEGY IMPACTS**

The impacts of control strategy reductions on 2007 8-hour ozone levels
were evaluated using the ozone model developed for the August 13-22,
1999 episode (NETAC, 2004).

**Control Strategy 1**

Figure 1 shows the decrease in episode maximum 8-hour ozone and Table 2
shows the projected 2007 8-hour ozone design values for Control Strategy
1 (CTL01). The only significant element of Control Strategy 1 is the
HRVOC reduction at the chemical facilities near Longview. Figure 1 shows
8-hour ozone decreases near Longview of up to \~0.4 ppb. The episode
maximum 8-hour ozone at the Longview monitor is reduced by \~0.2 ppb.
Control Strategy 1 does not alter the 2007 design values (Tables 1 and
2) in part because the 2007 design values are truncated to the next
lowest ppb. The relative reduction factor (RRF) for Longview is 0.981
for the 2007 base case and 0.980 for Control Strategy 1 (see Tables 1
and 2). This difference amounts to about a 0.1 ppb improvement in the
2007 design value calculation for Longview, which is too small to notice
after the design value has been truncated to the nearest ppb (80 ppb in
both Tables 1 and 2).

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  **Figure 1**. Decrease in episode maximum 8-hour ozone due to Control
  Strategy 1 (CTL01).
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**Table 2**. Projected 2007 8-hour ozone design values (ppb) for Control
Strategy 1 (CTL01).

  ------------------------- --------------- --------------- ---------------
  Monitor                   2001-2003 DV    Modeled RRF     Scaled 2007 DV

  Longview                  82              0.980           80

  Tyler                     81              0.954           77

  Karnack                   84              0.958           80

  Waskom                    84              0.966           81
  ------------------------- --------------- --------------- ---------------

**Control Strategy 2**

Figure 2 shows the decrease in episode maximum 8-hour ozone and Table 3
shows the projected 2007 8-hour ozone design values for Control Strategy
2 (CTL02). The significant elements of Control Strategy 2 are the TERP
NOx reductions for off-road mobile sources and the HRVOC reductions at
the chemical facilities near Longview. Figure 2 shows 8-hour ozone
decreases throughout the NETAC area with the largest decrease of \~0.6
ppb near Tyler. Control Strategy 2 does not alter the 2007 design values
in part because the 2007 design values are truncated to the next lowest
ppb. Comparing the relative reduction factors (RRFs) in Tables 1 and 2
shows improvement in the 2007 design value calculations of \~0.2 ppb for
Tyler and Longview, which are too small to notice after the design
values have been truncated to the nearest ppb.

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  ![](media/image3.png){width="5.000694444444444in"
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  **Figure 2**. Decrease in episode maximum 8-hour ozone due to Control
  Strategy 2 (CTL02).
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**Table 3**. Projected 2007 8-hour ozone design values (ppb) for Control
Strategy 2 (CTL02).

  ------------------------- --------------- --------------- ---------------
  Monitor                   2001-2003 DV    Modeled RRF     Scaled 2007 DV

  Longview                  82              0.979           80

  Tyler                     81              0.951           77

  Karnack                   84              0.958           80

  Waskom                    84              0.965           81
  ------------------------- --------------- --------------- ---------------

[TERP NOx Reduction]{.underline}

The impact of the 1.5 ton/day TERP NOx reduction for off-road mobile
sources is the difference between Control Strategies 2 and 1, shown in
Figure 3. The TERP NOx reduction results in 8-hour ozone decreases
throughout the NETAC area with the largest reductions near Tyler. This
is because Tyler is the largest urban area and therefore has the highest
concentration of off-road NOx emissions in the NETAC area.

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  **Figure 3**. Decrease in episode maximum 8-hour ozone due to the TERP
  NOx reduction for off-road mobile sources (Control Strategy 2 minus
  Control Strategy 1).
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**Conclusions**

-   HRVOC reductions at the Eastman and Huntsman chemical facilities
    near Longview result in 8-hour ozone decreases of up to \~0.4 ppb in
    the vicinity of these sources.

-   The TERP NOx reduction for off-road mobile sources results in 8-hour
    ozone decreases throughout the NETAC area of up to \~0.6 ppb near
    Tyler.

-   The ozone benefits of the HRVOC and TERP NOx strategies are too
    small to see in the projected 2007 design values because the design
    values are truncated to the next lowest ppb.

**References**

NETAC (2004). "Clean Air Action Plan for Northeast Texas." Report
prepared for the East Texas Council of Governments by the Northeast
Texas Air Care Technical Committee. March 31, 2004.

TCEQ (2004). "New NETAC 2007 ozone simulation." Memo from Gerry Wolfe
(TCEQ) to Greg Yarwood, September 4, 2004.