# ALGONQUIN GAS TRANSMISSION, L.L.C. (SPECTRA ENERGY PARTNERS, LP) — Corrective Action Order **Citation:** CPF 12020014CAO **Type / status:** enforcement / historical **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2020-10-01 CLOSED corrective action order. ## Document text Corrective Action Order involving ALGONQUIN GAS TRANSMISSION, L.L.C. (SPECTRA ENERGY PARTNERS, LP). The dataset does not identify a cited regulation for this case. The case was opened on 2020-10-01 and is reported as closed as of 2021-11-17. Open the official case record for notices, responses, orders, and the latest status. Official case documents: 12020014CAO_Amended Corrective Action Order_10302020_(20-172418).pdf: https://primis.phmsa.dot.gov/enforcement-documents/12020014CAO/12020014CAO_Amended%20Corrective%20Action%20Order_10302020_(20-172418).pdf 12020014CAO_Amended Corrective Action Order_10302020_(20-172418)_text.pdf: https://primis.phmsa.dot.gov/enforcement-documents/12020014CAO/12020014CAO_Amended%20Corrective%20Action%20Order_10302020_(20-172418)_text.pdf 12020014CAO_Closure Letter_11172021_(20-172418).pdf: https://primis.phmsa.dot.gov/enforcement-documents/12020014CAO/12020014CAO_Closure%20Letter_11172021_(20-172418).pdf 12020014CAO_Closure Letter_11172021_(20-172418)_text.pdf: https://primis.phmsa.dot.gov/enforcement-documents/12020014CAO/12020014CAO_Closure%20Letter_11172021_(20-172418)_text.pdf 12020014CAO_Corrective Action Order_10012020_(20-172418).pdf: https://primis.phmsa.dot.gov/enforcement-documents/12020014CAO/12020014CAO_Corrective%20Action%20Order_10012020_(20-172418).pdf 12020014CAO_Corrective Action Order_10012020_(20-172418)_text.pdf: https://primis.phmsa.dot.gov/enforcement-documents/12020014CAO/12020014CAO_Corrective%20Action%20Order_10012020_(20-172418)_text.pdf 12020014CAO_Operator Hearing Request Withdrawn_11042020_(20-172418).pdf: https://primis.phmsa.dot.gov/enforcement-documents/12020014CAO/12020014CAO_Operator%20Hearing%20Request%20Withdrawn_11042020_(20-172418).pdf 12020014CAO_Operator Request for Hearing and Statement of Issues_10132020_(20-172418).pdf: https://primis.phmsa.dot.gov/enforcement-documents/12020014CAO/12020014CAO_Operator%20Request%20for%20Hearing%20and%20Statement%20of%20Issues_10132020_(20-172418).pdf 12020014CAO_Amended Corrective Action Order_10302020_(20-172418)_text.pdf October 30, 2020 VIA ELECTRONIC MAIL TO: bill.yardley@enbridge.com Mr. William T. Yardley President, Gas Transmission and Midstream Enbridge, Inc. 5400 Westheimer Court Houston, Texas 77056 CPF No. 1-2020-014-CAO Dear Mr. Yardley: Enclosed please find an Amended Corrective Action Order (ACAO) issued by the Pipeline and Hazardous Materials Safety Administration (PHMSA), Office of Pipeline Safety (OPS), in the above-referenced case. It requires Algonquin Gas Transmission, LLC, a subsidiary of Enbridge Inc., to take certain corrective actions with respect to Algonquin’s Weymouth Compressor Station in Weymouth, Massachusetts. Service of the ACAO by electronic mail is deemed complete upon transmission and acknowledgement of receipt, or as otherwise provided under 49 C.F.R. § 190.5. The terms and conditions of this Order are effective upon completion of service. Sincerely, Alan K. Mayberry Associate Administrator for Pipeline Safety Enclosure: ACAO cc: Ms. Linda Daugherty, Deputy Associate Administrator for Field Operations, OPS Mr. Robert Burrough, Director, Eastern Region, OPS Ms. Michele Harradence, SVP & Chief Operating Officer, Gas Transmission and Midstream, michele.harradence@enbridge.com Mr. Nathan Atanu, Manager, Operational Compliance, Algonquin Gas Transmission, LLC, nathan.atanu@enbridge.com CONFIRMATION OF RECEIPT REQUESTED U.S. DEPARTMENT OF TRANSPORTATION PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION OFFICE OF PIPELINE SAFETY WASHINGTON, D.C. 20590 ____________________________________ In the Matter of ) Algonquin Gas Transmission, LLC, ) CPF No. 1-2020-014-CAO a subsidiary of Enbridge, Inc., ) ) ) ) Respondent. ) ____________________________________) AMENDED CORRECTIVE ACTION ORDER Purpose and Background: This Amended Corrective Action Order (ACAO or Order) is being issued under the authority of 49 U.S.C. § 60112 to require Algonquin Gas Transmission, LLC (AGT or Respondent), a subsidiary of Enbridge, Inc.,1 to take the necessary corrective actions to protect the public, property, and the environment from potential hazards associated with the unplanned emergency shutdown events at its Weymouth Compressor Station in Weymouth, Massachusetts (Station). On September 11, 2020, the Station experienced an O-ring gasket failure on a sump tank during the Station’s commissioning activities (Event 1). The failure triggered the manual operation of the emergency shutdown system and the release of approximately 169 thousand cubic feet (mscf) of natural gas. On September 30, 2020, at approximately 10:30 AM, the Station experienced an unplanned emergency shutdown, resulting in the release of approximately 195 mscf of natural gas (Event 2). The circumstances surrounding the failure of the O-ring gasket in Event 1, as well as the cause for the emergency shutdown in Event 2 (collectively, Events), are under investigation. Pursuant to 49 U.S.C. § 60117, PHMSA, Office of Pipeline Safety (OPS), initiated an investigation of the Events. As a result of our investigation and additional information provided by AGT, PHMSA is issuing this ACAO to clarify a few of the preliminary facts and to modify the definitions. The ACAO does not make any substantive changes to the corrective actions prescribed in the CAO. The preliminary findings of the agency’s ongoing investigation are as follows: 1 Enbridge, Inc. website, National Gas Transmission and Midstream, available at https://www.enbridge.com/About-Us/Natural-Gas-Transmission-and-Midstream.aspx (last accessed September 30, 2020). CPF No. 1-2020-014-CAO Page 2 Preliminary Findings:  The Station is the final part of AGT’s Atlantic Bridge Pipeline Project (Project). The Project involved replacing a 6.3-mile (10-kilometer) 26-inch-diameter pipe section with a 42-inch pipe in New York and Connecticut. The Project also involved installing a new meter station in Connecticut, modifications to various metering stations spread across several states, installation of four new compressor units at existing facilities, and a new compressor station in Weymouth, Massachusetts. The Project was designed to provide an additional 132,700 dekatherms of capacity on the AGT pipeline system and the Maritimes & Northeast pipeline system.  Weymouth, Massachusetts, is a heavily populated suburb outside of Boston, Massachusetts. The Station is in a high consequence area, and is located near Fore River Bridge, a heavily trafficked commuter road.  The Station has a station design pressure of 1440 pounds per square inch gauge (psig).  The Station experienced a gasket failure that triggered the manual activation of its emergency shutdown system, as well as an unplanned emergency shutdown due to unknown reasons, less than three weeks apart.  There were no injuries or fatalities associated with the Events; however, the release of large quantities of pressurized natural gas in a heavily populated area carries a substantial risk of fire, explosion, and personal injury or death, and releases natural gas into the environment.  On September 30, 2020, the inlet pressure at the Station was 683 psig; the discharge pressure at the time of the emergency shutdown was 707 psig.  AGT is performing a root cause failure analysis on the O-ring gasket failure that caused Event 1.  The reason for Event 2 is unknown and under investigation.  The Station is currently shut-in. Determination of Necessity for Corrective Action Order and Right to Hearing: Section 60112 of title 49, United States Code, authorizes PHMSA to determine that a pipeline facility is or would be hazardous to life, property, or the environment and, if there is a likelihood of serious harm, to expeditiously order the operator of the facility to take necessary corrective action, including suspended or restricted use of the facility, physical inspection, testing, repair, replacement, or other appropriate action. An order issued expeditiously must provide an opportunity for a hearing as soon as practicable after the order is issued. CPF No. 1-2020-014-CAO Page 3 In deciding whether to issue an order, PHMSA must consider the following, if relevant: (1) the characteristics of the pipe and other equipment used in the pipeline facility, including the age, manufacture, physical properties, and method of manufacturing, constructing, or assembling the equipment; (2) the nature of the material the pipeline facility transports, the corrosive and deteriorative qualities of the material, the sequence in which the material are transported, and the pressure required for transporting the material; (3) the aspects of the area in which the pipeline facility is located, including climatic and geologic conditions and soil characteristics; (4) the proximity of the area in which the hazardous liquid pipeline facility is located to environmentally sensitive areas; (5) the population density and population and growth patterns of the area in which the pipeline facility is located; (6) any recommendation of the National Transportation Safety Board made under another law; and (7) any other factors PHMSA may consider appropriate. After evaluating the foregoing preliminary findings of fact, and having considered that the Station had an O-ring gasket failure that triggered the manual operation of its emergency shutdown system and an unplanned emergency shutdown for unknown reasons within three weeks of each other; the uncertainties as to the cause of Event 2; and the Station’s location in a High Consequence Area, and proximity to populated areas and highly-trafficked public roads, I find that continued operation of the Station without corrective measures is or would be hazardous to life, property, or the environment, and that failure to issue this Order expeditiously would result in the likelihood of serious harm. Accordingly, this Amended Corrective Action Order mandating immediate corrective action is issued without prior notice and opportunity for a hearing. The terms and conditions of this Order are effective upon receipt. Within 10 days of receipt of this Order, Respondent may request a hearing, to be held as soon as practicable, by notifying the Associate Administrator for Pipeline Safety in writing, with a copy to the Director, Eastern Region, PHMSA (Director). If a hearing is requested, it will be held in accordance with 49 C.F.R. § 190.211. After receiving and analyzing additional data in the course of this investigation, PHMSA may identify other corrective measures that need to be taken. Respondent will be notified of any additional measures required and, if appropriate, PHMSA will consider amending or withdrawing this Order, if warranted by new supporting information. To the extent consistent with safety, Respondent will be afforded notice and an opportunity for a hearing prior to the imposition of any additional corrective measures. Required Corrective Actions: Definitions: Isolated Segment – Means the Weymouth Compressor Station, from inlet valves to outlet valves. CPF No. 1-2020-014-CAO Page 4 Director – Means the Director, Pipeline and Hazardous Materials Safety Administration (PHMSA), Office of Pipeline Safety, Eastern Region. The Director’s address is 840 Bear Tavern Road, Suite 300, West Trenton, NJ 08626. Pursuant to 49 U.S.C. 60112, I hereby order AGT to immediately take the following corrective actions for the Isolated Segment: 1. Shutdown of the Isolated Segment. The Isolated Segment is currently shut-in and not in operation. AGT must not operate the Isolated Segment until authorized to do so by the Director. 2. Restart Plan. Prior to resuming operation of the Isolated Segment, AGT must develop and submit a written Restart Plan to the Director for approval. a. The Director may approve the Restart Plan incrementally without approving the entire plan but the Isolated Segment cannot resume operation until the Restart Plan is approved in its entirety. b. Once approved by the Director, the Restart Plan will be incorporated by reference into this Order. c. The Restart Plan must provide for adequate patrolling of the Isolated Segment during the restart process and must include incremental pressure increases during start-up, with each increment to be held for at least two hours. d. The Restart Plan must include sufficient surveillance of the Isolated Segment during each pressure increment to ensure that no leaks are present when operation of the pipeline facility resumes. e. The Restart Plan must specify a day-light restart and include advance communications with local emergency response officials. f. The Restart Plan must provide for a review of the Isolated Segment for conditions similar to those that caused the Events, including a review of construction and commissioning records. AGT must address any findings that require remedial measures to be implemented prior to restart. g. The Restart Plan must also include documentation of the completion of all mandated actions, and a management of change plan to ensure that all procedural modifications are incorporated into AGT’s operations and maintenance procedures manual. 3. Return to Service. After the Director approves the Restart Plan, AGT may return the Isolated Segment to service but the operating pressure must not exceed eighty percent (80%) of the actual operating pressure in effect immediately prior to Event 2, in accordance with Item 2 above. 4. Removal of Pressure Restriction. The Director may allow the removal or modification of the pressure restriction upon a written request from AGT demonstrating that restoring the CPF No. 1-2020-014-CAO Page 5 Isolated Segment to its pre-Event 2 operating pressure is justified based on a reliable engineering analysis showing that the pressure increase is safe, considering all known defects, anomalies, and operating parameters of the Isolated Segment. 5. Temporary Removal of Pressure Restriction. The Director may allow the temporary removal or modification of the pressure restrictions upon a written request from AGT demonstrating that temporary mitigative and preventive measures are being implemented prior to and during the temporary removal or modification of the pressure restriction. The Director's determination will be based on the known or suspected cause of Event 2 and the provision of evidence that preventive and mitigative actions taken by the operator provide for the safe operation of the Isolated Segment during the temporary removal or modification of the pressure restriction. Appeals to determinations of the Director in this regard will be decided by the Associate Administrator for Pipeline Safety. 6. Root Cause Failure Analysis. Within 90 days following receipt of this Order, complete a root cause failure analysis (RCFA) and submit a final report of this RCFA to the Director. The RCFA must be supplemented or facilitated by an independent third-party acceptable to the Director and must document the decision-making process and all factors contributing to Event 2. The final report must include findings and any lessons learned and whether the findings and any lessons learned are applicable to other locations within AGT’s pipeline system. Other Requirements: 7. Approvals. With respect to each submission that under this Order requires the approval of the Director, the Director may: (a) approve, in whole or part, the submission; (b) approve the submission on specified conditions; (c) modify the submission to cure any deficiencies; (d) disapprove in whole or in part, the submission, directing that Respondent modify the submission, or (e) any combination of the above. In the event of approval, approval upon conditions, or modification by the Director, Respondent shall proceed to take all action required by the submission as approved or modified by the Director. If the Director disapproves all or any portion of the submission, Respondent must correct all deficiencies within the time specified by the Director, and resubmit it for approval. 8. Extensions of Time. The Director may grant an extension of time for compliance with any of the terms of this Order upon a written request timely submitted demonstrating good cause for an extension. 9. Reporting. Submit monthly reports to the Director that: (1) include all available data and results of the testing and evaluations required by this Order; and (2) describe the progress of the repairs or other remedial actions being undertaken. The first monthly report is due on November 27, 2020. The Director may change the interval for the submission of these reports. 10. Documentation of the Costs. It is requested but not required that Respondent maintain documentation of the costs associated with implementation of this Corrective Action Order. Include in each monthly report submitted, the to-date total costs associated with: CPF No. 1-2020-014-CAO Page 6 (1) preparation and revision of procedures, studies and analyses; (2) physical changes to pipeline infrastructure, including repairs, replacements and other modifications; and (3) environmental remediation, if applicable. Be advised that all material you submit in response to this enforcement action is subject to being made publicly available. If you believe that any portion of your responsive material qualifies for confidential treatment under 5 U.S.C. § 552(b), along with the complete original document you must provide a second copy of the document with the portions you believe qualify for confidential treatment redacted and an explanation of why you believe the redacted information qualifies for confidential treatment under 5 U.S.C. § 552(b). In your correspondence on this matter, please refer to “CPF No. 1-2020-014-CAO” and for each document you submit, please provide a copy in electronic format whenever possible. The actions required by this Order are in addition to and do not waive any requirements that apply to Respondent’s pipeline system under 49 C.F.R. Parts 190 through 199, under any other order issued to Respondent under authority of 49 U.S.C. Chapter 601, or under any other provision of Federal or State law. Respondent may appeal any decision of the Director to the Associate Administrator for Pipeline Safety. Decisions of the Associate Administrator shall be final. Failure to comply with this Order may result in the assessment of civil penalties and in referral to the Attorney General for appropriate relief in United States District Court pursuant to 49 U.S.C. § 60120. The terms and conditions of this Order are effective upon service in accordance with 49 C.F.R. § 190.5. October 30, 2020 _________________________________ ________________________ Alan K. Mayberry Date Issued Associate Administrator for Pipeline Safety 12020014CAO_Corrective Action Order_10012020_(20-172418)_text.pdf October 1, 2020 VIA ELECTRONIC MAIL TO: bill.yardley@enbridge.com Mr. William T. Yardley President, Gas Transmission and Midstream Enbridge, Inc. 5400 Westheimer Court Houston, Texas 77056 CPF No. 1-2020-014-CAO Dear Mr. Yardley: Enclosed please find a Corrective Action Order (CAO) issued by the Pipeline and Hazardous Materials Safety Administration (PHMSA), Office of Pipeline Safety (OPS), in the above- referenced case. It requires Algonquin Gas Transmission, LLC, a subsidiary of Enbridge Inc., to take certain corrective actions with respect to Algonquin’s Weymouth Compressor Station in Weymouth, Massachusetts. Service of the CAO by electronic mail is deemed complete upon transmission and acknowledgement of receipt, or as otherwise provided under 49 C.F.R. § 190.5. The terms and conditions of this Order are effective upon completion of service. Sincerely, Alan K. Mayberry Associate Administrator for Pipeline Safety Enclosure: CAO cc: Ms. Linda Daugherty, Deputy Associate Administrator for Field Operations, OPS Mr. Robert Burrough, Director, Eastern Region, OPS Ms. Michele Harradence, SVP & Chief Operating Officer, Gas Transmission and Midstream, michele.harradence@enbridge.com Mr. Nathan Atanu, Manager, Operational Compliance, Algonquin Gas Transmission, LLC, nathan.atanu@enbridge.com CONFIRMATION OF RECEIPT REQUESTED U.S. DEPARTMENT OF TRANSPORTATION PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION OFFICE OF PIPELINE SAFETY WASHINGTON, D.C. 20590 ____________________________________ In the Matter of ) Algonquin Gas Transmission, LLC, ) CPF No. 1-2020-014-CAO a subsidiary of Enbridge, Inc., ) ) ) ) Respondent. ) ____________________________________) CORRECTIVE ACTION ORDER Purpose and Background: This Corrective Action Order (CAO or Order) is being issued under the authority of 49 U.S.C. § 60112 to require Algonquin Gas Transmission, LLC (AGT or Respondent), a subsidiary of Enbridge, Inc.,1 to take the necessary corrective actions to protect the public, property, and the environment from potential hazards associated with the multiple unplanned emergency shutdown events at its Weymouth Compressor Station in Weymouth, Massachusetts (Station). On September 11, 2020, the Station experienced an O-ring gasket failure on a sump tank during the Station’s commissioning activities (Incident 1). The failure triggered the manual operation of the emergency shutdown system and the release of approximately 169 thousand cubic feet (mscf) of natural gas. On September 30, 2020, at approximately 10:30 AM, the Station experienced an unplanned emergency shutdown, resulting in the release of approximately 275 mscf of natural gas (Incident 2). The circumstances surrounding the failure of the O-ring gasket in Incident 1, as well as the cause for the emergency shutdown in Incident 2 (collectively, Incidents) are under investigation. Pursuant to 49 U.S.C. § 60117, PHMSA, Office of Pipeline Safety (OPS), initiated an investigation of the Incidents. The preliminary findings of the agency’s ongoing investigation are as follows: Preliminary Findings:  The Station is part of the AGT’s Atlantic Bridge Pipeline Project (Project). The Project involves replacing a 6.3-mile (10-kilometer) 26-inch-diameter pipe section with a 42- inch pipe in New York and Connecticut. The Project also involves installing a new 1 Enbridge, Inc. website, National Gas Transmission and Midstream, available at https://www.enbridge.com/About-Us/Natural-Gas-Transmission-and-Midstream.aspx (last accessed September 30, 2020). CPF No. 1-2020-014-CAO Page 2 meter station in Connecticut, modifications to various metering stations spread across several states, installation of four new compressor units at existing facilities, and a new compressor station in Weymouth, Massachusetts. When completed, the Project will provide an additional 132,700 dekatherms of capacity on the AGT pipeline system and the Maritimes & Northeast pipeline system.  Weymouth, Massachusetts, is a heavily populated suburb outside of Boston, Massachusetts. The Station is in a high consequence area, and is located near Fore River Bridge, a heavily trafficked commuter road.  The Station has a station design pressure of 1440 pounds per square inch gauge (psig).  The Station experienced a gasket failure that triggered the manual activation of its emergency shutdown system, as well as an unplanned emergency shutdown due to unknown reasons, less than three weeks apart.  There were no injuries or fatalities associated with the Incidents; however, the release of large quantities of pressurized natural gas in a heavily populated area carries a substantial risk of fire, explosion, and personal injury or death and releases harmful methane into the environment.  On September 30, 2020, the inlet pressure at the Station was 683 psig; the discharge pressure at the time of the emergency shutdown was 707 psig.  AGT is performing a root cause failure analysis on the O-ring gasket failure that caused Incident 1.  The reason for Incident 2 is unknown and under investigation.  The Station is currently shut-in. Determination of Necessity for Corrective Action Order and Right to Hearing: Section 60112 of title 49, United States Code, authorizes PHMSA to determine that a pipeline facility is or would be hazardous to life, property, or the environment and, if there is a likelihood of serious harm, to expeditiously order the operator of the facility to take necessary corrective action, including suspended or restricted use of the facility, physical inspection, testing, repair, replacement, or other appropriate action. An order issued expeditiously must provide an opportunity for a hearing as soon as practicable after the order is issued. In deciding whether to issue an order, PHMSA must consider the following, if relevant: (1) the characteristics of the pipe and other equipment used in the pipeline facility, including the age, manufacture, physical properties, and method of manufacturing, constructing, or assembling the equipment; (2) the nature of the material the pipeline facility transports, the corrosive and CPF No. 1-2020-014-CAO Page 3 deteriorative qualities of the material, the sequence in which the material are transported, and the pressure required for transporting the material; (3) the aspects of the area in which the pipeline facility is located, including climatic and geologic conditions and soil characteristics; (4) the proximity of the area in which the hazardous liquid pipeline facility is located to environmentally sensitive areas; (5) the population density and population and growth patterns of the area in which the pipeline facility is located; (6) any recommendation of the National Transportation Safety Board made under another law; and (7) any other factors PHMSA may consider appropriate. After evaluating the foregoing preliminary findings of fact, and having considered that the Station had an O-ring gasket failure that triggered the manual operation of its emergency shutdown system and an unplanned emergency shutdown for unknown reasons within the past three weeks; the uncertainties as to the cause of Incident 2; and the Station’s location in a High Consequence Area, and proximity to populated areas and highly-trafficked public roads, I find that continued operation of the Station without corrective measures is or would be hazardous to life, property, or the environment, and that failure to issue this Order expeditiously would result in the likelihood of serious harm. Accordingly, this Corrective Action Order mandating immediate corrective action is issued without prior notice and opportunity for a hearing. The terms and conditions of this Order are effective upon receipt. Within 10 days of receipt of this Order, Respondent may request a hearing, to be held as soon as practicable, by notifying the Associate Administrator for Pipeline Safety in writing, with a copy to the Director, Southwest Region, PHMSA (Director). If a hearing is requested, it will be held in accordance with 49 C.F.R. § 190.211. After receiving and analyzing additional data in the course of this investigation, PHMSA may identify other corrective measures that need to be taken. Respondent will be notified of any additional measures required and, if appropriate, PHMSA will consider amending or withdrawing this Order, if warranted by new supporting information. To the extent consistent with safety, Respondent will be afforded notice and an opportunity for a hearing prior to the imposition of any additional corrective measures. Required Corrective Actions: Definitions: Affected Pipeline – The Weymouth Compressor Station, including incoming pipeline, I- 10, back to first upstream mainline valve. Isolated Segment – Means the Weymouth Compressor Station, from inlet valves to outlet valves. Director – Means the Director, Pipeline and Hazardous Materials Safety Administration (PHMSA), Office of Pipeline Safety, Eastern Region. The Director’s address is 840 Bear Tavern Road, Suite 300, West Trenton, NJ 08626. CPF No. 1-2020-014-CAO Page 4 Pursuant to 49 U.S.C. 60112, I hereby order AGT to immediately take the following corrective actions for the Affected Pipeline and Isolated Segment: 1. Shutdown of the Isolated Segment. The Isolated Segment is currently shut-in and not in operation. AGT must not operate the Isolated Segment until authorized to do so by the Director. 2. Restart Plan. Prior to resuming operation of the Isolated Segment, AGT must develop and submit a written Restart Plan to the Director for approval. a. The Director may approve the Restart Plan incrementally without approving the entire plan but the Isolated Segment cannot resume operation until the Restart Plan is approved in its entirety. b. Once approved by the Director, the Restart Plan will be incorporated by reference into this Order. c. The Restart Plan must provide for adequate patrolling of the Isolated Segment during the restart process and must include incremental pressure increases during start-up, with each increment to be held for at least two hours. d. The Restart Plan must include sufficient surveillance of the Isolated Segment during each pressure increment to ensure that no leaks are present when operation of the line resumes. e. The Restart Plan must specify a day-light restart and include advance communications with local emergency response officials. f. The Restart Plan must provide for a review of the Isolated Segment for conditions similar to those that caused the Incidents, including a review of construction and commissioning records. AGT must address any findings that require remedial measures to be implemented prior to restart. g. The Restart Plan must also include documentation of the completion of all mandated actions, and a management of change plan to ensure that all procedural modifications are incorporated into AGT’s operations and maintenance procedures manual. h. Prior to restart, AGT must submit to the Director a contingency plan to operate and monitor the Isolated Segment during flooding conditions, including enhanced patrolling and surveillance. 3. Return to Service. After the Director approves the Restart Plan, AGT may return the Isolated Segment to service but the operating pressure must not exceed eighty percent (80%) of the actual operating pressure in effect immediately prior to Incident 2, in accordance with Item 2 above. CPF No. 1-2020-014-CAO Page 5 4. Removal of Pressure Restriction. The Director may allow the removal or modification of the pressure restriction upon a written request from AGT demonstrating that restoring the pipeline to its pre-Incident 2 operating pressure is justified based on a reliable engineering analysis showing that the pressure increase is safe, considering all known defects, anomalies, and operating parameters of the pipeline. The Director may allow the removal or modification of the pressure restriction upon a written request from AGT demonstrating that restoring the Affected Segment to its pre- Incident 2 operating pressure is justified, based on a reliable engineering analysis showing that the pressure increase is safe, considering all known defects, anomalies, and operating parameters of the pipeline. 5. Temporary Removal of Pressure Restriction. The Director may allow the temporary removal or modification of the pressure restrictions upon a written request from AGT demonstrating that temporary mitigative and preventive measures are being implemented prior to and during the temporary removal or modification of the pressure restriction. The Director's determination will be based on the known or suspected cause of Incident 2 and the provision of evidence that preventive and mitigative actions taken by the operator provide for the safe operation of the Affected Segment during the temporary removal or modification of the pressure restriction. Appeals to determinations of the Director in this regard will be decided by the Associate Administrator for Pipeline Safety. 6. Root Cause Failure Analysis. Within 90 days following receipt of this Order, complete a root cause failure analysis (RCFA) and submit a final report of this RCFA to the Director. The RCFA must be supplemented or facilitated by an independent third-party acceptable to the Director and must document the decision-making process and all factors contributing to Incident 2. The final report must include findings and any lessons learned and whether the findings and any lessons learned are applicable to other locations within AGT’s pipeline system. Other Requirements: 7. Approvals. With respect to each submission that under this Order requires the approval of the Director, the Director may: (a) approve, in whole or part, the submission; (b) approve the submission on specified conditions; (c) modify the submission to cure any deficiencies; (d) disapprove in whole or in part, the submission, directing that Respondent modify the submission, or (e) any combination of the above. In the event of approval, approval upon conditions, or modification by the Director, Respondent shall proceed to take all action required by the submission as approved or modified by the Director. If the Director disapproves all or any portion of the submission, Respondent must correct all deficiencies within the time specified by the Director, and resubmit it for approval. 8. Extensions of Time. The Director may grant an extension of time for compliance with any of the terms of this Order upon a written request timely submitted demonstrating good cause for an extension. 9. Reporting. Submit quarterly reports to the Director that: (1) include all available data and results of the testing and evaluations required by this Order; and (2) describe the progress CPF No. 1-2020-014-CAO Page 6 of the repairs or other remedial actions being undertaken. The first quarterly report is due on January 4, 2021. The Director may change the interval for the submission of these reports. 10. Documentation of the Costs. It is requested but not required that Respondent maintain documentation of the costs associated with implementation of this Corrective Action Order. Include in each monthly report submitted, the to-date total costs associated with: (1) preparation and revision of procedures, studies and analyses; (2) physical changes to pipeline infrastructure, including repairs, replacements and other modifications; and (3) environmental remediation, if applicable. Be advised that all material you submit in response to this enforcement action is subject to being made publicly available. If you believe that any portion of your responsive material qualifies for confidential treatment under 5 U.S.C. § 552(b), along with the complete original document you must provide a second copy of the document with the portions you believe qualify for confidential treatment redacted and an explanation of why you believe the redacted information qualifies for confidential treatment under 5 U.S.C. § 552(b). In your correspondence on this matter, please refer to “CPF No. 1-2020-014-CAO” and for each document you submit, please provide a copy in electronic format whenever possible. The actions required by this Order are in addition to and do not waive any requirements that apply to Respondent’s pipeline system under 49 C.F.R. Parts 190 through 199, under any other order issued to Respondent under authority of 49 U.S.C. Chapter 601, or under any other provision of Federal or State law. Respondent may appeal any decision of the Director to the Associate Administrator for Pipeline Safety. Decisions of the Associate Administrator shall be final. Failure to comply with this Order may result in the assessment of civil penalties and in referral to the Attorney General for appropriate relief in United States District Court pursuant to 49 U.S.C. § 60120. The terms and conditions of this Order are effective upon service in accordance with 49 C.F.R. § 190.5. October 1, 2020 _________________________________ ________________________ Alan K. Mayberry Date Issued Associate Administrator for Pipeline Safety 12020014CAO_Closure Letter_11172021_(20-172418)_text.pdf VIA ELECTRONIC MAIL TO: Bill.Yardley@enbridge.com November 17, 2021 Mr. William T. Yardley President, Gas Transmission and Midstream Enbridge, Inc. 5400 Westheimer Court Houston, Texas 77056 CPF 1-2020-014-CAO Dear Mr. Yardley: On October 1, 2020, and on October 30, 2020, the Pipeline and Hazardous Materials Safety Administration (PHMSA) issued a Corrective Action Order (CAO) and an Amended Corrective Action Order (ACAO), respectively, to Algonquin Gas Transmission, LLC (AGT), a subsidiary of Enbridge, Inc., with regard to the September 11, 2020 and September 30, 2020 events at Weymouth Compressor Station. The ACAO included a list of various required Corrective Actions. We have received a final monthly report, dated August 13, 2021, from Mr. Nathan Atanu, Manager, Operational Compliance. We have also received eight earlier monthly reports, submitted as part of the final Corrective Action deliverable, required under item 9 of the ACAO. Subsequently, a letter from Mr. Atanu was received on August 18, 2021 requesting closure of the ACAO. During our review of the documentation, a PHMSA investigator performed multiple on-site visits to verify completion of corrective actions. The investigator was on site to view Phase 1 through Phase 4 of the approved Restart Plan from December 4 to 7, 2020. The Weymouth Compressor Station was operating at 683 pounds per square inch gauge (psig) at the time of Event 2. Leakage surveys of the Isolated Segment of Weymouth Compressor Station were performed and reviewed during the two (2) hour hold periods of each phase. After receiving appropriate approval to proceed to Phase 5 of the Restart Plan, AGT completed a Temporary Removal of Pressure Restriction, which was also verified by the investigator. The Root Cause Failure Analysis (RCFA) was received by PHMSA on December 22, 2020. The ACAO requires that all recommendations from the RCFA be incorporated into AGT’s Operations and Maintenance Manual. This was completed and subsequently reviewed and verified by the PHMSA investigator on August 18, 2021. PHMSA reminds AGT of the requirements enacted by Congress and described in Section 114 of the “Protecting our Infrastructure of Pipelines and Enhancing Safety Act of 2020” (PIPES Act of 2020), which requires all pipeline operators to address the elimination of hazardous leaks and minimization of releases of natural gas. Please refer to PHMSA Advisory Bulletin ADB-2021- 01, for more information on this self-executing provision. PHMSA will be conducting inspections of these modified plans in 2022. CPF 1-2020-014-CAO PHMSA also requests that AGT continue to maintain relationships and open communication with state and local authorities such as the Massachusetts Department of Environmental Protection, the Town of Weymouth, the Town of Braintree, and the City of Quincy. PHMSA is also aware that AGT has initiated and completed additional safety measures in addition to the requirements of the ACAO. For example, AGT has utilized Pipeline Safety Management System (PSMS) principles to perform additional risk assessments to Weymouth Compressor Station systems outside the scope of the ACAO and have incorporated the lessons learned. AGT had a third party review the Emergency Shutdown (ESD) system and have incorporated all the recommended enhancements into policies and procedures. Finally, AGT continues to perform weekly leakage surveys throughout the compressor station, a practice which started back in November 2020. Based on our review of the documentation you provided, it has been determined that you have complied with the terms of this Order. Accordingly, this CAO is now closed. It is our expectation that AGT will aggressively implement methane emission reduction strategies at this facility and other locations along its pipeline systems. As noted previously, PHMSA will be inspecting all pipeline facilities across the country to ensure alignment with statutory requirements for reducing methane emissions. Thank you for your cooperation in this matter. Sincerely, Robert Burrough Director, Eastern Region Pipeline and Hazardous Materials Safety Administration cc: Ms. Linda Daugherty, Deputy Associate Administrator for Field Operations, OPS (PHMSA) Mr. Thomas Wooden, Vice President, Northeast Transmission (Enbridge) Mr. Nathan Atanu, Manager, Operational Compliance (Enbridge) 12020014CAO_Closure Letter_11172021_(20-172418)_text Page 2 of 2 ## Provenance - Official: Yes - Source: - Source ID: `phmsa-enforcement` - SHA-256: `4240c4ad78257763def554cf195687d1d422afc1e193b31e738c5dbdad3bf407` - Retrieved: 2026-08-20T04:44:44.458Z - Exported: 2026-08-23T02:39:27.571Z - Document slug: `phmsa-enforcement-12020014cao` ### Source metadata ```json { "cpf": "12020014CAO", "operator": "ALGONQUIN GAS TRANSMISSION, L.L.C. 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Agency-issued documents may also include a verified local PDF and page-level text representation.", "jurisdiction": "US", "operatorName": "ALGONQUIN GAS TRANSMISSION, L.L.C. (SPECTRA ENERGY PARTNERS, LP)" } ```