**VIRGINIA DEPARTMENT OF ENVIRONMENTAL QUALITY**

**Valley Regional Office**

INTRA-AGENCY MEMORANDUM

4411 Early Road - P. O. Box 3000 Harrisonburg, VA 22801-3000

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+---------------------+---+----------+------------+---+------+-----------+
| **Permit Writer**   |   | *Anita   |            |   | **Da | *1/25/07* |
|                     |   | Ri       |            |   | te** |           |
|                     |   | ggleman* |            |   |      |           |
+---------------------+---+----------+------------+---+------+-----------+
| **Air Permit        |   | *Sharon  |            |   | **Da | *1/25/07* |
| Manager**           |   | G.       |            |   | te** |           |
|                     |   | Foley*   |            |   |      |           |
+---------------------+---+----------+------------+---+------+-----------+
| **Deputy Regional   |   | *Larry   |            |   | **Da | *1/25/07* |
| Director**          |   | M.       |            |   | te** |           |
|                     |   | Simmons* |            |   |      |           |
+---------------------+---+----------+------------+---+------+-----------+
| **Memo To**         |   | Air      |            |   |      |           |
|                     |   | Permit   |            |   |      |           |
|                     |   | File     |            |   |      |           |
+---------------------+---+----------+------------+---+------+-----------+
| **Facility Name**   | T |          |            |   |      |           |
|                     | r |          |            |   |      |           |
|                     | a |          |            |   |      |           |
|                     | n |          |            |   |      |           |
|                     | s |          |            |   |      |           |
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|                     | a |          |            |   |      |           |
|                     | l |          |            |   |      |           |
|                     | G |          |            |   |      |           |
|                     | a |          |            |   |      |           |
|                     | s |          |            |   |      |           |
|                     | P |          |            |   |      |           |
|                     | i |          |            |   |      |           |
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|                     | e |          |            |   |      |           |
|                     | l |          |            |   |      |           |
|                     | i |          |            |   |      |           |
|                     | n |          |            |   |      |           |
|                     | e |          |            |   |      |           |
|                     | - |          |            |   |      |           |
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|                     | S |          |            |   |      |           |
|                     | t |          |            |   |      |           |
|                     | a |          |            |   |      |           |
|                     | t |          |            |   |      |           |
|                     | i |          |            |   |      |           |
|                     | o |          |            |   |      |           |
|                     | n |          |            |   |      |           |
|                     | 1 |          |            |   |      |           |
|                     | 7 |          |            |   |      |           |
|                     | 5 |          |            |   |      |           |
+---------------------+---+----------+------------+---+------+-----------+
| **Registration      |   | 40789    |            |   |      |           |
| Number**            |   |          |            |   |      |           |
+---------------------+---+----------+------------+---+------+-----------+
| **County-Plant      |   | 065-0016 |            |   |      |           |
| I.D.**              |   |          |            |   |      |           |
+---------------------+---+----------+------------+---+------+-----------+
| **UTM Coordinates** |   | 726.8    | *          | 4 |      | *         |
|                     |   |          | *Easting** | 1 |      | *Northing |
| **(Zone 17)**       |   |          |            | 9 |      | (km)**    |
|                     |   |          | **(km)**   | 0 |      |           |
|                     |   |          |            | . |      |           |
|                     |   |          |            | 8 |      |           |
+---------------------+---+----------+------------+---+------+-----------+
| **Elevation**       |   | 500      |            |   |      |           |
|                     |   |          |            |   |      |           |
| **(feet)**          |   |          |            |   |      |           |
+---------------------+---+----------+------------+---+------+-----------+
| **Distance to       |   | \~40     | **SNP**    |   |      | **JRF**   |
| Nearest Class I     |   |          |            |   |      |           |
| Area**              |   |          | **(km)**   |   |      | **(km)**  |
|                     |   |          |            |   |      |           |
| **(select one)**    |   |          |            |   |      |           |
+---------------------+---+----------+------------+---+------+-----------+
| **FLM Notification  |   | N        |            |   |      |           |
| Required**          |   |          |            |   |      |           |
|                     |   |          |            |   |      |           |
| **(Y/N)**           |   |          |            |   |      |           |
+---------------------+---+----------+------------+---+------+-----------+
| **AFS               |   | A        | **Before   | A |      | **After   |
| Classification**    |   |          | permit**   |   |      | permit**  |
|                     |   |          |            |   |      |           |
| **(A, SM, B)**      |   |          | **action** |   |      | *         |
|                     |   |          |            |   |      | *action** |
+---------------------+---+----------+------------+---+------+-----------+
| **Pollutants for    |   | NO~x~,   | **Before   | N |      | **After   |
| Which**             |   | CO, VOC  | permit     | O |      | permit**  |
|                     |   |          | action**   | ~ |      |           |
| **the Source is     |   |          |            | x |      | *         |
| Title V**           |   |          |            | , |      | *action** |
|                     |   |          |            | ~ |      |           |
| **Major**           |   |          |            | C |      |           |
|                     |   |          |            | O |      |           |
|                     |   |          |            | , |      |           |
|                     |   |          |            | V |      |           |
|                     |   |          |            | O |      |           |
|                     |   |          |            | C |      |           |
+---------------------+---+----------+------------+---+------+-----------+
| **PSD Major         |   | Y        | **Before   | Y |      | **After   |
| Source**            |   |          | permit     |   |      | permit**  |
|                     |   |          | action**   |   |      |           |
| **(Y/N)**           |   |          |            |   |      | *         |
|                     |   |          |            |   |      | *action** |
+---------------------+---+----------+------------+---+------+-----------+
| **Pollutants for    |   | NO~x~,   | **Before   | N |      | **After   |
| Which**             |   | CO, VOC  | permit     | O |      | permit**  |
|                     |   |          | action**   | ~ |      |           |
| **the Source is PSD |   |          |            | x |      | *         |
| Major**             |   |          |            | , |      | *action** |
|                     |   |          |            | ~ |      |           |
|                     |   |          |            | C |      |           |
|                     |   |          |            | O |      |           |
|                     |   |          |            | , |      |           |
|                     |   |          |            | V |      |           |
|                     |   |          |            | O |      |           |
|                     |   |          |            | C |      |           |
+---------------------+---+----------+------------+---+------+-----------+

**I. Introduction**

> Transcontinental Gas Pipeline (Transco) -- Compressor Station 175 is
> owned by Williams Gas Pipeline. Transco is an interstate natural gas
> transmission company. Transco's 1,900-mile pipeline system transports
> natural gas from production areas in the Gulf Coast region to
> customers along the eastern seaboard. Transco's compressor stations
> are used to compress and move the gas along the system. Compression is
> made possible through the application of natural gas-fired, internal
> combustion, reciprocating compressor engines. The compressor station
> is located at 1344 Transco Road in Fluvanna County, Virginia. A Title
> V Operating permit was issued to Transco on 02/05/02. The Title V
> Operating permit expires on 02/05/07.
>
> The NO~x~ SIP Call Rule (63 FR 57356, October 27, 1998 and 69 FR
> 21604, April 21, 2004), addresses the interstate transport of ozone.
> It requires twenty-one States and the District of Columbia to
> eliminate those amounts of NO~x~ emissions that contribute
> significantly to downwind nonattainment of the 1-hour ozone standard.
> EPA estimated the amount of NO~x~ emissions in a State by 2007 taking
> into consideration the effect of existing control measures and
> projected growth. This is known as the 2007 base year emissions
> inventory. EPA then applied highly cost-effective control measures to
> the 2007 base year emissions. This is known as the 2007 budget or
> controlled inventory. The amount of NO~x~ emissions that contribute
> significantly to nonattainment was determined to be the difference
> between the 2007 base year emissions inventory and the 2007 budget.
>
> In the NO~x~ SIP Call Phase II Rule (69 FR 21604), the 2007 base year
> emissions inventory was recalculated to reflect partial State emission
> for Alabama, Georgia, Michigan, and Missouri and 82 percent control
> instead of 90 percent control for gas-fired lean burn engines in the
> stationary internal combustion (IC) engine source category.
>
> Due to the administrative burden associated with the regulatory
> process and time constraints, Virginia DEQ decided to use an
> alternative approach to developing the legally enforceable mechanism
> to implement the EPA requirements for Phase II of the NO~x~ SIP call. 
> Virginia DEQ will impose the emission limits and other requirements by
> permit instead of by regulation.  This approach was chosen because
> only internal combustion (IC) engines need to be regulated as a part
> of the NO~x~ SIP call and there are only a few of those in the state.
>
> On December 2, 2005, a Form 7 application was received from Williams
> Gas Pipeline for a State Operating Permit (SOP) for the four existing
> mainline natural gas-fired reciprocating engines located at Transco's
> Compressor Station 175. Transco seeks a federally-enforceable limit on
> this group of engines (as a whole) that will essentially cap NO~x~
> emissions to an ozone season (May 01 -- September 30) tonnage limit
> based on the budget set forth by the NO~x~ SIP Call Phase II.
>
> Emissions calculations for the four affected engines at Transco's
> Compressor Station 175 are included in Attachment A. These
> calculations show the potential-to-emit of NO~x~ for the 1995 ozone
> season, the projected NO~x~ emissions for the 2007 ozone season and
> the proposed emission limits.

**II. Emission Unit(s) / Process Description(s)**

> The NO~x~ SIP Call Phase II permit application was received for the
> following affected units:

  -------- ----------------------- ---------------- -------------- --------- ------------
  **Unit   **Equipment             **Date of        **Maximum      **Type of **Output
  Ref.     Manufacturer, Type and  Installation**   Rated Input    Fuel**    Brake
  No.**    Model Number**                           Heat Capacity            Horsepower
                                                    (MMBtu/hr)**             (BHP)**

  M01      Cooper-Bessemer         1960             37.0           Natural   4,400
           LSV-16SG four stroke                                    gas       
           spark-ignited lean burn                                           
           (4SLB) reciprocating IC                                           
           engine (RICE)                                                     

  M02      Cooper-Bessemer         1960             37.0           Natural   4,400
           LSV-16SG 4SLB RICE                                      gas       

  M03      Cooper-Bessemer         1960             37.0           Natural   4,400
           LSV-16SG 4SLB RICE                                      gas       

  M04      Cooper-Bessemer         1960             37.0           Natural   4,400
           LSV-16SG 4SLB RICE                                      gas       
  -------- ----------------------- ---------------- -------------- --------- ------------

# III. Regulatory Review

A. [9 VAC 5 Chapter 80, Article 5 - State Operating Permit
Review]{.underline}

> Per 9 VAC 5-80-800 C.2.b, DEQ may issue a State Operating Permit to
> establish a source-specific emission standard or other requirement
> necessary to implement the federal Clean Air Act or the Virginia Air
> Pollution Control Law. Accordingly, the proposed State Operating
> Permit will be issued to establish NO~x~ SIP Call Phase II conditions.
>
> B. [9 VAC 5 Chapter 80, Part II, Article 6 - Minor New Source
> Review]{.underline}
>
> Transco is not proposing to construct or modify any emission unit.
> Therefore, minor new source review is not required.
>
> C. [9 VAC 5 Chapter 80, Article 8 - PSD Major New Source
> Review]{.underline}
>
> This facility is a PSD major source. Transco is not proposing to
> construct or modify any emission unit. Therefore, major new source
> review is not required.
>
> D. [9 VAC 5 Chapter 50, Part II, Article 5 - NSPS]{.underline}
>
> No applicable NSPS standards apply to this facility.

E. [9 VAC 5 Chapter 60, Part II, Article 1 - NESHAPS]{.underline}

> No applicable NESHAP standards apply to this facility.
>
> F. [9 VAC 5 Chapter 60, Part II, Article 2 - MACT]{.underline}
>
> The Reciprocating Internal Combustion Engines (RICE) MACT (40 CFR 63
> Subpart ZZZZ), promulgated June 15, 2004, is not applicable to this
> facility. The compliance date for an existing source for Subpart ZZZZ
> is June 15, 2007. 40 CFR 63.6590(b)(3) states that a stationary RICE
> which is an existing spark ignition 4 stroke lean burn (4SLB)
> stationary RICE does not have to meet the requirements of this subpart
> and the General Provisions (40 CFR Part 63, Subpart A) and no initial
> notification is necessary. The applicability of the RICE MACT may be
> addressed further during the upcoming Title V renewal process.

# IV. Best Available Control Technology Review (BACT) (9 VAC 5-50-260)

A BACT review is not necessary. There are no new emissions units subject
to minor new source review.

V.  **Summary of Controlled Emissions Increase**

> There are no increases in controlled emissions.

**VI. Dispersion Modeling**

> A. [Criteria Pollutants]{.underline}
>
> There are no increases in criteria pollutant emissions. Therefore, no
> modeling is required.
>
> B. [Toxic Pollutants]{.underline}
>
> There are no increases in toxic pollutant emissions. Therefore, no
> modeling is required.

**VII. Boilerplate Deviations**

The "NO~x~ Phase II SOP_DRAFT_FINAL.doc" was used to draft this SOP. The
only deviation from the boilerplate was to add the following emission
controls condition:

> Requests to increase the total hours of operation of the affected
> facility above the limit contained in Condition III.D.1 or an increase
> in the emission limits contained in Condition III.D.2 will result in
> the requirement to install low emission combustion (LEC) technology on
> the existing affected units to ensure compliance with the ozone season
> NO~x~ tonnage limit.

VIII. **Compliance Demonstration**

> The facility will ensure compliance with the permit through periodic
> monitoring as required in Condition III.C, testing as required in
> Condition III.E, and recordkeeping as required in Condition III.G of
> the permit. Over the last 5 years, the utilization of Transco's
> Station 175 has been nearly zero during the ozone season. Records of
> hours of operation will satisfy periodic monitoring requirements for
> any affected unit operating less than 45 hours during the ozone season
> (less than 10% utilization). Emissions testing for NO~x~ is required
> for any affected unit that operates equal to or greater than 45 hours
> per ozone season. Initial emissions testing on all four units is
> required before May 1, 2007.

**IX. Title V Review - 9 VAC 5 Chapter 80, Article 1**

> Transco is currently classified as a Title V major source and holds a
> Title V permit dated February 5, 2002. This will not change upon
> issuance of this permit.

**X. Site Suitability**

> Not Applicable. There are no changes to the facility and no increases
> in emissions.

XI. **Other Considerations**

> *[Load Shifting]{.underline}*
>
> EPA commented on the proposed compliance plan for Transco's Station
> 175 and sought assurance that the plan does not produce a situation
> where Transco complies with the NO~x~ SIP Call Phase II reductions
> through load shifting. Transco's response can be found in Attachment
> B. A summary of Transco's rationale is as follows:

-   Ozone season load shifting cannot occur at Station 175 as all four
    mainline compressor engines are "large" engines as defined by the
    NO~x~ SIP Call and are included in the proposed ozone season NO~x~
    tonnage limit.

-   Load shifting from Station 175 to other compressor facilities is not
    practicable as the hydrodynamics of pipeline operation require
    recompression at specific points along the pipeline to overcome
    pressure losses created by pipeline friction and gas deliveries.
    Arbitrarily shutting in a station is not feasible or economic as
    pressure losses through that section of pipeline could create
    situations where pipeline pressures fall below serviceable levels.

-   Station 175 historic operations demonstrate that the facility has
    not operated significantly during the last five consecutive ozone
    seasons. A review of ozone season operational data for Station 175
    and adjacent compressor stations (Station 170 and Station 180)
    indicate utilization has fallen off during this period for all three
    facilities. Further, Station 175 utilization (approx. 10% for 1995
    ozone season) trends along a similar curve as the adjacent stations
    (85% and 75% respectively) but at a significantly lower utilization
    rate. The spread in utilization rates is expected, as Station 175
    was constructed as an intermediate facility to ensure that Transco
    could meet peak winter deliveries. Station 175's historic ozone
    season operations demonstrate that due to the peaking nature of its
    operation, load shifting does not occur.

-   Transco seeks a permit that caps ozone season NO~x~ emissions from
    Station 175's mainline compressor engines to a tonnage limit based
    on the budget set forth by the NO~x~ SIP Call. Transco will continue
    to operate Station 175 at a utilization rate that would meet the
    ozone season NO~x~ tonnage limit. If required in the future, Transco
    is prepared to install LEC technology on these engines or replace
    these engines with lower emitting units to ensure compliance with
    the ozone season NO~x~ tonnage limit.

> The DEQ and EPA agree with Transco's rationale which outlines how the
> NOx SIP Call Phase II compliance plan for Station 175 does not involve
> load shifting to other units.

XII. **Public Participation**

> Notice of the draft State Operating Permit and the proposed revision
> to the Virginia SIP inviting public comment was placed in the
> Fredericksburg [Free Lance Star]{.underline} and the Charlottesville
> [Daily Progress]{.underline} newspapers and a public hearing was held
> in accordance with the applicable provisions of 9 VAC 5-80-1020 and 9
> VAC 5-170-100. The public notice period began August 24, 2006 and
> ended October 4, 2006. EPA was sent a link to the DEQ website
> containing a copy of the draft permit and notified of the public
> notice on August 17, 2006.
>
> Public and EPA comments were accepted from August 24, 2006 to October
> 4, 2006. The public hearing was held on October 4, 2006. No comments
> were received and no one attended the public hearing.

**XIII. Recommendations**

> Recommend approval of the State Operating Permit.

XIV. **Attachments**

Attachment A: Emissions Calculations

Attachment B: Transco's Response on Load Shifting

[]{.mark}

**ATTACHMENT A**

![](media/image1.wmf)

**ATTACHMENT B**