Authors: Pennsylvania Department of Environmental Protection

(PADEP)

Timothy Kuntz: 

Environmental Group Manager (Air Quality SWRO)

Thomas Norris: 

Air Quality Specialist (SWRO)

May 2014

SWRO: South West Regional Office
 This Power Point presentation is intended to discuss Air Quality GP5 field 

inspections of natural gas compressor stations in the State of Pennsylvania.

 The scope of this Power Point is to highlight a typical inspection by an Air Quality 

Field Inspector to ensure the station is in compliance.

 The GP5 issuance/renewal process is not discussed in this Power Point.

 GP5 issuance/renewal is handled by PADEP Engineers. As such, Air Quality 

Inspectors rely on documentation created by the Engineers during the permit 

review process to assist them in determining applicable State and Federal 

regulations.

 This Power Point will focus on the PA State regulations listed within the GP5. Federal 

regulations will not be thoroughly discussed.

 The following sources (Sections) within the 2013 GP5 will not be discussed:

• Section C. Requirements For Natural Gas-Fired Simple Cycle Gas Turbines

• Section D. Requirements For Centrifugal Compressors

• Section G. Requirements For Onshore Natural Gas Processing Plants

• Section I. Requirements For Pneumatic Controllers

• Section J. Requirements For Sweetening Units
The following process should be conducted by the Air Quality Inspector.

Before:

 Review station file for station familiarization. 

 Determine which GP5 version is applicable.

 Coordinate field inspection date/time with station owner.

During:

 Conduct GP5 permit review with station personnel and request 

pertinent documents.

 Verify station inventory matches permitted inventory.

 Conduct visual observations and take notes.

After:

 Pursue follow-up requests as needed.

 Write up inspection report.
 In the state of Pennsylvania, natural gas production (compressor) 

stations (conventional & unconventional) are regulated under a 

GP5.

 Applicable GP5 versions: 

 -8/2006 – GP5 issued/re-issued prior to 3/17/2011 

 -3/17/2011 – GP5 issued/re-issued between 3/17/2011 and 2/2/2013

 -2/2/2013 – GP5 issued/re-issued on or after 2/2/2013

 GP5 permits are applicable for a timeframe of five (5) years before 

re-issuance is required.

 GP5 permit renewal applications need to be submitted to the 

Department thirty (30) days prior to permit expiration.

 -(2006 & 2011 GP5 Condition 9)

 -(2013 GP5 Section A Condition 21)
 Differences between the 2006 and 2011 GP5 are minimal in 

regards to Air Quality Inspector inspections. 

 The 2011 GP5 is a ‘cleaned-up’ version in regards to language 

revisions throughout the document.

 The main difference is that the 2011 GP5 contains a paragraph 

under Condition 2 Titled: Potential to Emit Limitations. This 

condition allows the applicant to propose lower emission limits 

based on manufacturer’s specifications and other operational 

limits. This condition is not found within the 2006 GP5 version, nor 

has it been carried over into the 2013 GP5 version.

 Additionally, the revised 2011 GP5 clarified that federal new 

source performance standards and NESHAPs are applicable 

requirements. 
 For the most part, the contents of the 8/2006 and 3/17/2011 

GP5 versions have been carried over into the 2/2/2013 GP5 

version. Differences between the versions are:

-More sources are covered within the 2013 GP5.

-Stricter emission limits in the 2013 GP5.

-Emission limits are listed in the 2013 GP5 for sources 

 that were not included within the 2006/2011 GP5. -More stringent conditions are in the 2013 GP5 for 

 Glycol Dehydrators. -Additional conditions have been added to the 2013 

 GP5 that are not listed within the 2006/2011 GP5. -Applicable Federal Regulations are addressed within 

 the 2013 GP5.
Ensure the following written notifications have been submitted to the Department 

by the station owner/operator no later than five (5) business days prior to:

-Initial commencement date of construction of the source(s) authorized under the GP5.

(2013 GP5 Section A Condition 11c(i).

-...completion of construction and the intent to commence operation. 

(2006/2011 GP5 Condition 6).

-Final completion date of construction. (2013 GP5 Section A Condition 11c(ii).

-Any lapse in construction activity of eighteen (18) months or more that may take place in 

between the initial and start-up dates... (2013 GP5 Section A Condition 11c(iii)

...written notification...of the intent to commence operation of the....facility. When multiple 

sources...are subject to different commencement of operation schedules, written notice 

shall be submitted...prior to the commencement of operation of each source. 

(2013 GP5 Section A Condition 11d).
 Have any malfunctions been reported?

 Were they reported as per the GP5 condition?

 Review any reported malfunctions.

-2006/2011 GP5 Condition 6

-2013 GP5 Section A Condition 11e

Malfunction as defined within 2013 GP5 Section A Condition 11e:

...any malfunction of pollution control equipment associated with the 

facility, which results in, or may possibly be resulting in, the emission 

of air contaminants in excess of any applicable limitation specified 

herein.
 Fugitive Emissions and Malodors cannot leave facilities property.

-2006/2011 GP5 (odors only) Conditions 13a(ii) and 13c(v)

-2013 GP5 (fugitives & odors) Section A Conditions 9(iii) and 9(iv)

 Opacity limits apply to both engines and dehydrators. 

-2006/2011 GP5 Conditions 13a(i) or 13b(v) and 13c(iv)

-2013 GP5 Section B Condition 1c and Section F Condition 2d 

 There are no permit requirements that mandate the 

owner/operator conduct observations for fugitive emissions, 

odors or opacity or maintain a log of any observations.

 Inspector: Inquire about fugitive emission, odor and opacity 

compliance and conduct observations for each to determine 

compliance.
 Section A Condition 9c - ...emissions from all sources and associated air 

pollution control equipment... shall not equal or exceed the following on a 12- month rolling sum... -100 tons for NOx, CO, SOx, PM10, PM2.5

-50 tons for VOCs

-10 tons for any individual HAP

-25 tons for total HAPs

-100,000 tons for greenhouse gases, expressed as carbon dioxide equivalent (CO2e) *Note: Stricter NOx (25 tons) and VOC (25 tons) emission limits are listed for Bucks, Chester, Delaware, Montgomery and 

 Philadelphia counties.

 Section A Condition 14 – The owner/operator... shall maintain records that 

clearly demonstrate... that the facility is not a Title V facility.... and shall keep 

records to verify compliance with the facility-wide emission limitations (as 

listed within Section A Condition 9c).

 Inspector: Request records to show compliance with these conditions. Ensure 

records are maintained as a 12-month rolling sum. 

 Note: There are no facility-wide emission limits listed within the 2006/2011 GP5.
 Section A Condition 15 - ...the owner/operator... shall submit to 

the Department by March 1st each year a source report for the 

preceding calendar year for all sources regulated under this 

General Permit. Emissions data including, but not limited to the 

following, shall be reported: 

 CO, NOx, PM10, PM2.5, SOx, VOCs, Total HAPs, Speciated 

 Individual HAPs and Greenhouse Gases expressed as CO2e.

 Inspector: Confirm that the appropriate Emissions Inventory 

Report has been submitted in a timely manner.

 Note: This condition is not listed within the 2006/2011 GP5, however, PADEP has 

sent out a letter to all GP5 permitted facilities to submit this report regardless of the 

GP5 version they are currently permitted under. This condition pertains to 

unconventional gas facilities only.
 Upon review of the station file and DEP Engineer 

review documents, the inspector needs to determine 

the specific applicable GP5 conditions for each engine. 

Determine if Federal Part 63 Subparts JJJJ and/or ZZZZ 

regulations apply.

 Verify that the on-site station inventory matches the 

GP5 permitted sources. 

 Verify if each engine is existing, new or reconstructed. 

If reconstructed, determine date of reconstruction.

 Verify air pollution control equipment.

 Observe operating parameters of each engine and 

take notes as applicable.
 Request annual hours of operation and fuel used 

for each engine (2006/2011 GP5 Condition 17a).

 Request monthly hours of operation and fuel used for 

each engine (2013 GP5 Section B Condition 5b).

 Note if there are any differences between 

the station and what was reported within the 

permit application.

 Ask to review engine maintenance records.

 Verify compliance with applicable Federal 

Part 63 Subpart JJJJ and/or ZZZZ regulations.
 Upon review of the station file and DEP Engineer review 

documents, the inspector needs to determine which specific GP5 

performance testing conditions apply (if any) for each engine.

 Within all GP5 versions, engines equal to or less than 500 bhp do 

not need initial or subsequent emission tests. 

 Within all GP5 versions, engines greater than 500 bhp must have 

an initial emissions test conducted and conduct subsequent 

portable analyzer tests thereafter.

 Inspector: Ensure station has submitted the proper initial testing 

notifications in a timely manner and review for compliance. 

 Inspector: Request and review all applicable portable analyzer 

test reports for compliance.
 The 2006/2011 GP5 versions do not have any conditions that apply 

to storage tanks listed.

 2013 GP5 – Section E – Requirements For Storage Vessels/Storage Tanks

-Must comply with 40 CFR Subparts Kb, OOOO and HH.

-Tank capacity greater than 40,000 gallons shall comply with 

 25 PA Codes 129.56.

-Tank capacity less than or equal to 40,000 gallons shall comply 

 with 25 PA Code129.57.

 Inspector: Compliance with these conditions is typically conducted 

during the engineer permit review process. Inspector should conduct a 

visual observation of tanks to confirm inventory, confirm tank labelling is 

correct, determine that the condition of the tank is sound and ensure 

covers, lids or seals are in the closed position except during required 

tank operations.

 Annual tank emissions should be submitted within the facilities annual 

emission inventory reports.
 Determine if 40 CFR Part 63 Subpart HH applies (engineer review) and 

ensure compliance if applicable. Request proof of HH exemption if 

applicable.

 Determine units uncontrolled VOC Tons Per Year emissions to determine 

applicable GP5 conditions (engineer review). 

- >10 Tons Per Year then Condition 13c and Condition 17c applies. 

- ≤10 TPY then the unit is exempt from Condition 13c & 17c and Condition 

 17d applies. 
 If >10 TPY VOC and not exempt, Condition 13c and 17c apply

 Condition 13c:

• (i) Ensure unit is outfitted with a VOC control device with at least 85% efficiency.

• (ii) If condenser is used, ensure an average final exhaust temperature of less than 110 

degrees Fahrenheit is achieved daily.

• (iii) If flare is used, ensure that VOC emissions destruction is achieved by maintaining the 

heat content of the flare gas above 300 BTU/scf and document daily visual observations of 

the continuous presence of a flame. Inspector requests proof of compliance.

• (iv) Unit opacity limitations: 10% for a period or periods aggregating more than 3 minutes 

in any one hour and 30% at any time.

• (v) Malodors from the unit are not detectable off the facility property.

 Condition 17c:

• (i) Request any test reports if applicable.

• (ii) If unit uses a condenser, a record of final exhaust temperature and time observed shall 

be recorded twice per week on different days during daylight hours. Inspector requests 

log.

• (iii) If unit uses a flare, a record of daily visual observations of the continuous presence of a 

flame shall be recorded. Inspector requests log.

• (iv) Inspector requests to review records of maintenance and repairs and records of the 

duration of uncontrolled emissions during such activities. 
 If ≤10 TPY VOC and exempt from Conditions 13c and 17c, then Condition 

17d applies:

-(i) Inspector request records of VOC emissions using GRI-GLYCalc 

 computer software or an alternative method approved by the Department.

-(ii) Inspector requests records of actual throughput per day and the glycol 

 circulation rate.

 For all dehydrator units permitted under a 2006/2011 GP5, regardless of 

exemption, Condition 17a applies:

- Inspector requests records of number of hours and amount of fuel 

 used per calendar year for each applicable dehydrator.

*Note: These same conditions have been carried over into the 2013 GP5 

version under Section F Conditions 1 & 2. 
 Determine if unit is existing or new. If unit is existing (constructed prior to 

2/2/13) Section F Condition 2 is applicable (covered under the 2006/2011 

GP5 section). If unit is new (constructed after 2/2/13) then 2013 GP5 Section F 

Conditions 3 & 4 apply.

 Section F Condition 1: Determine if 40 CFR Part 63 Subpart HH applies 

(engineer review) and ensure compliance if applicable. Request proof of HH 

exemption if applicable.

 Section F Condition 3: If unit is not subject to Subpart HH and has a total uncontrolled potential emission rate of VOC >5 TPY it must be outfitted with an air cleaning device capable of at least 95% VOC destruction efficiency. In addition, Section F Condition 2 (b) through (j) also apply (which have been covered under 2006/2011 GP5 section).

 Section F Condition 4: If unit is not subject to Subpart HH and has a total 

uncontrolled potential emission rate of VOC ≤5 TPY it must comply with the 

requirements in Section F Condition 2 (d), (e) and (j) (which have been 

covered under the 2006/2011 GP5 section). 
 Condition 1: Facility must perform a monthly leak detection and 

repair program that includes audible, visual and olfactory (AVO) 

inspections. Inspector requests records of these inspections.

 Condition 2: Facility must conduct quarterly fugitive leak 

inspections using a forward looking infrared camera (FLIR) or 

other Department approved leak detection monitoring devices. 

Compliance is due within 180 days of issuance of the 2013 GP5 or 

within 180 days of construction/installation of a new source 

covered under the 2013 GP5. Inspector requests inspection 

reports.

 Condition 3: If a leak is detected it shall be repaired no later than 

15 days after discovery (except provided in 40 CFR 60.482-9). 

Records of each leak detected and the repair activity shall be 

maintained. Inspector requests records.
 Unauthorized use of an unpermitted source

 Operation without Plan Approval/Permit

 Emissions Testing (Excess Emissions)

 Visual Emission, Fugitive Emission, Odors

 Failure to maintain the appropriate records

 Failure to submit paperwork in a timely 

manner:

-Notifications

-Permit Applications (Initial or Renewal)

-Request For Determinations (RFD)

-Annual Emission Reports (Due by March 1st)

-Change of Ownership (requires new GP5)
 PADEP Website: 

http://www.depweb.state.pa.us/portal/server.pt/community/dep_home/5968

 PADEP Air Quality General Permits: 

http://www.depweb.state.pa.us/portal/server.pt/community/dep_home/5968 Natural Gas Compression and/or Processing Facilities. 

• Conditions (PDF) 

• Fact Sheet (PDF) 

• Comment/Response Document (PDF) 

• Changes to Previous Permit (PDF of PowerPoint) 

• Technical Support Document (PDF)

Amended on 4/9/13

• Internal Implementation Instructions for Exemption Category No. 38 (PDF) 

• FAQ – Implementation of GP-5 and Exemption No. 38 (PDF) 

• Summary of 40CFR60 IIII (Excel) 

• Summary of 40CFR60 JJJJ (Excel) 

• Summary of 40CFR63 HH (Excel) 

• Summary of 40CFR63 ZZZZ (Excel) 

 PADEP Plan Approval/Operating Permit Applications, Exemptions Listing and Request 

For Determination: 

http://www.dep.state.pa.us/dep/deputate/airwaste/aq/permits/plan.htm
Inspecting Natural Gas 

Compressor Stations in 

Pennsylvania

Authors: Pennsylvania Department of Environmental Protection (PADEP)

Timothy Kuntz: 

Environmental Group Manager (Air Quality SWRO)

Thomas Norris: 

Air Quality Specialist (SWRO)

May 2014

SWRO: South West Regional Office