Failure Report- Enbridge Energy, Limited Partnership 7/28/10

Page 1Official PDFDOT US Department of Transportation PHMSA Pipeline and Hazardous Materials Safety Administration OPS Office of Pipeline Safety Central Region Principal Investigator Dan Munthe (MNOPS) PHMSA Investigators Bryan Louque/Karen Butler Region Director David Barrett/Allan Beshore Date of Report 05/30/2015 Subject Failure Investigation Report—Enbridge Energy, Limited Partnership— Line 1 Leak, Equipment Failure Operator, Location, & Consequences Date of Failure 07/28/2010 Commodity Released Crude Oil City/County & State Cass Lake/Cass, MN OpID & Operator Name 11169 Enbridge Energy, Limited Partnership Unit # & Unit Name 3083 ALL LINES IN MINNESOTA [IA] SMART Activity # 130804 Milepost / Location MP 958.33/Mainline Valve Setting Type of Failure Leak—Equipment Failure on Line 1 Fatalities 0 Injuries 0 Description of area impacted Pipeline Right-of-Way, Rural, Non-HCA Total Cost $18,352#

Page 2Failure Investigation Report – Enbridge Energy, Limited Partnership – Leak, Equipment Failure Failure Date 07/28/2010 Executive Summary1 At approximately 7:45 a.m. CDT2 on July 28, 2010, a painting crew working for Enbridge Energy, L.P. (Enbridge), discovered a crude oil leak located in Cass Lake, Cass County, MN. The leak occurred on the pipeline right-of-way (ROW) at a mainline valve setting located approximately four miles east of the Enbridge North Cass Lake pump station. No evacuations, injuries, or fatalities occurred as a result of the crude oil release. The accident did not occur in a High Consequence Area (HCA) and surface water was not affected. An estimated 10 gallons of crude oil were released. The total cost of the accident was reported as $18,352. The Minnesota Office of Pipeline Safety (MNOPS) sent a pipeline investigator to the failure location and conducted an investigation. There were no service interruptions or supply impacts as a result of the accident even though Line 1 and Line 2 were shut down for a brief period to confirm the pipeline source of the release. The cause of the release was worn valve stem packing on the 18-inch nominal diameter gate valve installed in 1951, located on Line 1 at MP 958.33. The valve stem packing was replaced on site and the pipeline returned to service later the same day. System Details Line 1 originates in Edmonton, Alberta, Canada, and crosses the U. S. border near Neche, ND. Line 1 consists of 136 miles of 20” nominal diameter pipe stretching from the U.S. border to the Clearbrook, MN Terminal and 189 miles of 18” nominal diameter pipe traveling from Clearbrook, MN, to Superior, WI. Line 1 terminates in Superior, WI. There are eight pumping stations associated with the U.S. portion of Line 1 (Joliette, ND—MP 792; Viking, MN—MP 848; Clearbrook, MN—MP 909; Wilton, MN— MP 929; North Cass Lake, MN—MP 953; Deer River, MN—MP 996; Blackberry, MN—MP 1018; and Floodwood, MN—MP 1053). In the location where the valve stem leaked the pipeline is constructed with 18” nominal diameter API 5L X-46 flash-welded line pipe manufactured by A.O. Smith and installed in 1950. The pipe at the failure location has a 0.281” wall (thickness) that is coated with coal tar enamel and cathodically protected. The maximum operating pressure (MOP) of Line 1 at the time of the failure was 837psig. The gate valve located at MP 958.33 was manufactured by M&J Valve Company and installed in 1951. A system based on supervisory control and data acquisition (SCADA) was in place and operating on the pipeline at the time of failure, but a leak detection system was not. The leak was too small to be detected by the existing SCADA system or by a formal leak detection system. Events Leading up to the Failure A painting crew working for Enbridge on above-ground appurtenances discovered crude oil at approximately 7:45 a.m. at the MP 958.33 mainline valve setting. The maintenance crew contacted an Enbridge supervisor who confirmed release at the failure site. The Enbridge product lifecycle 1 This Failure Investigation Report is based upon facts and information available to PHMSA and MNOPS at the time of issuance. Any statements, conclusions, appendices, data summaries, or findings stated herein are subject to revision and do not constitute any final determination about the need for further investigation or enforcement action by any government agency. 2 All times are shown in Central Daylight Time unless otherwise noted. Page 2 of 3#

Page 3Failure Investigation Report – Enbridge Energy, Limited Partnership – Leak, Equipment Failure Failure Date 07/28/2010 management (PLM) supervisor contacted the Enbridge Control Center and had the controllers shut down both Line 1 and Line 2, as both pipelines were in close proximity to the confirmed leak location. Enbridge shut the pipelines down at approximately 8:00 a.m., and the crude oil released did not migrate beyond the immediate area. Approximately 10 gallons of crude oil were released from the pipeline into the surrounding soil, and the pressure at the Line 1 MP 958.33 valve setting at the time of failure was 393 psig. Emergency Response After the Enbridge controllers shut down Line 1 and Line 2, the pipeline was isolated using remote controlled valves between the North Cass Lake and Deer River pump stations. Enbridge notified the National Response Center (NRC) at 10:37 a.m. (NRC Report No. 949152) and dispatched additional employees to the MP 958.33 valve setting. The Pipeline and Hazardous Materials Safety Administration (PHMSA) was notified at 11:45 a.m. by MNOPS, which had an investigator on the way to the accident site. Enbridge reported the leak location as slightly north of the intersection of Pike Bay Loop NW and Highway 2 in Cass Lake, MN (on the east side of lake). Field crews excavated the pipeline with shovels at the leak site; in situ visual inspection of the pipeline revealed that crude oil was leaking from the mainline valve stem packing. Summary of Return-to-Service Enbridge personnel were able to repack the valve stem on site without removing the valve from the pipeline. The repair required the packing seal retainer to be tightened. In addition to making the repairs, monitoring wells were installed. Once the repair was completed and inspected, the contaminated soil was removed from the site by a contractor and disposed of at an off-site facility. Enbridge returned the pipeline to service at full operating pressure at 5:45 p.m. on the same day the leak occurred (July 28, 2010). Findings and Contributing Factors The Enbridge Line 1 leak at MP 958.33 was caused by equipment failure that allowed crude oil to leak through a worn valve stem packing on a gate valve located at the mainline valve setting. The gate valve was originally installed in 1951. The valve stem packing was replaced on site and the pipeline was returned to service the same day. PHMSA, in conjunction with MNOPS, reviewed the operator’s PHMSA reported leak history for valve- related failures and did not find a systemic problem associating this type of valve with packing leaks. Appendices A Map and Photographs B NRC Report C Operator Accident Report D Interstate Agent PIM Page 3 of 3#

Page 4Appendix A - Map and Photographs Pipeline and Hazardous Materials Safety Administration Enbridge Line 1 Release, Cass Lake, MN 10 20 40 60 PHMSA CENTRAL REGION • Miles Page 1 of 2#

Page 5Appendix A - Map and Photographs Page 2 of 2#

Page 6Appendix B - NRC Report NATIONAL RESPONSE CENTER 1-800-424-8802 *** For Public Use *** Information released to a third party shall comply with any applicable federal and/or state Freedom of Information and Privacy Laws Incident Report # 949152 INCIDENT DESCRIPTION *Report taken at 11:37 on 28-JUL-10 Incident Type: PIPELINE Incident Cause: UNKNOWN Affected Area: The incident was discovered on 28-JUL-10 at 09:15 local time. Affected Medium: SUBSURFACE SUBSURFACE AND SOIL ____________________________________________________________________________ SUSPECTED RESPONSIBLE PARTY Organization: ENBRIDGE SUPERIOR, WI 54880 Type of Organization: PRIVATE ENTERPRISE ____________________________________________________________________________ INCIDENT LOCATION NEAR CASS LAKE County: CASS PIPELINE MILEPOST 958.33 City: CASS LAKE State: MN Distance from City: 3 MILES Direction from City: SE ____________________________________________________________________________ RELEASED MATERIAL(S) CHRIS Code: OIL Official Material Name: OIL: CRUDE Also Known As: Qty Released: 5 BARREL(S) ____________________________________________________________________________ DESCRIPTION OF INCIDENT CALLER IS REPORTING THAT A GALLON OF CRUDE WAS DISCOVERED BUBBLING UP FROM SUBSURFACE. TWO LINES IN THE AREA HAVE BEEN SHUT DOWN WHILE CHECKING FOR THE EXACT SOURCE. CALLER IS ESTIMATED 5 BARRELS RELEASED FROM THE UNDERGROUND PIPELINE AT THIS TIME. ____________________________________________________________________________ INCIDENT DETAILS Pipeline Type: TRANSMISSION DOT Regulated: YES Pipeline Above/Below Ground: BELOW Exposed or Under Water: NO Pipeline Covered: UNKNOWN ____________________________________________________________________________ DAMAGES Fire Involved: NO Fire Extinguished: UNKNOWN INJURIES: NO Hospitalized: Empl/Crew: Passenger: FATALITIES: NO Empl/Crew: Passenger: Occupant: EVACUATIONS: NO Who Evacuated: Radius/Area: Damages: NO Length of Direction of Closure Type Description of Closure Closure Closure Air: N Road: N Major Artery: N Waterway: N Page 1 of 2#

Page 7Appendix B - NRC Report Track: N Passengers Transferred: NO Environmental Impact: UNKNOWN Media Interest: NONE Community Impact due to Material: ____________________________________________________________________________ REMEDIAL ACTIONS TWO LINES IN THE AREA IS SECURED AND ISOLATED. MOBILIZING EQUIPMENT TO EXCAVATE AND INVESTIGATE. Release Secured: YES Release Rate: Estimated Release Duration: ____________________________________________________________________________ WEATHER Weather: SUNNY, 80ºF ____________________________________________________________________________ ADDITIONAL AGENCIES NOTIFIED Federal: NONE State/Local: NONE State/Local On Scene: NONE State Agency Number: NONE ____________________________________________________________________________ NOTIFICATIONS BY NRC ATLANTIC STRIKE TEAM (MAIN OFFICE) 28-JUL-10 11:43 USCG ICC (ICC ONI) 28-JUL-10 11:43 DOT CRISIS MANAGEMENT CENTER (MAIN OFFICE) 28-JUL-10 11:43 U.S. EPA V (MAIN OFFICE) 28-JUL-10 11:45 MN BUREAU OF CRIMINAL APPREHENSION (OPERATIONS CENTER) 28-JUL-10 11:43 MN DEPT OF HEALTH (MAIN OFFICE) 28-JUL-10 11:43 MN U.S. ATTORNEY'S OFFICE (MAIN OFFICE) 28-JUL-10 11:43 NATIONAL INFRASTRUCTURE COORD CTR (MAIN OFFICE) 28-JUL-10 11:43 NOAA RPTS FOR MN (MAIN OFFICE) 28-JUL-10 11:43 PIPELINE & HAZMAT SAFETY ADMIN (OFFICE OF PIPELINE SAFETY (AUTO)) 28-JUL-10 11:43 ____________________________________________________________________________ ADDITIONAL INFORMATION CALLER WILL MAKE NOTIFICATIONS TO STATE AGENCIES. ___________________________________________________________________________ *** END INCIDENT REPORT # 949152 *** The National Response Center is strictly an initial report taking agency and does not participate in the investigation or incident response. The NRC receives initial reporting information only and notifies Federal and State On-Scene Coordinators for response. The NRC does not verify nor does it take follow-on incident information. Verification of data and incident response is the sole responsibility of Federal/State On-Scene Coordinators. Data contained within the FOIA Web Database is initial information only. All reports provided via this server are for informational purposes only. Data to be used in legal proceedings must be obtained via written correspondence from the NRC. Page 2 of 2#

Page 8Appendix C - Operator's Report NOTICE: This report is required by 49 CFR Part 195. Failure to report can result in a civil penalty not to exceed $100,000 for each violation for each day that such violation persists except that the maximum civil penalty shall not exceed $1,000,000 as provided in 49 USC 60122. OMB NO: 2137-0047 EXPIRATION DATE: 01/31/2013 Report Date: 08/27/2010 U.S Department of Transportation Pipeline and Hazardous Materials Safety Administration No. 20100184 - 15264 -------------------------- (DOT Use Only) ACCIDENT REPORT - HAZARDOUS LIQUID PIPELINE SYSTEMS A federal agency may not conduct or sponsor, and a person is not required to respond to, nor shall a person be subject to a penalty for failure to comply wi h a collection of information subject to the requirements of the Paperwork Reduction Act unless hat collection of information displays a current valid OMB Control Number. The OMB Control Number for this information collection is 2137-0047. Public reporting for this collection of informa ion is es imated to be approximately 10 hours per response (5 hours for a small release), including he ime for reviewing instructions, gathering the data needed, and comple ing and reviewing the collection of information. All responses to his collection of information are mandatory. Send comments regarding this burden es imate or any other aspect of this collection of information, including sugges ions for reducing this burden to: Information Collection Clearance Officer, PHMSA, Office of Pipeline Safety (PHP-30) 1200 New Jersey Avenue, SE, Washington, D.C. 20590. INSTRUCTIONS Important: Please read the separate instructions for completing this form before you begin. They clarify the information requested and provide specific examples. If you do not have a copy of the instructions, you can obtain one from the PHMSA Pipeline Safety Community Web Page at http://www.phmsa dot gov/pipeline. PART A - KEY REPORT INFORMATION Report Type: (select all that apply) Original: Supplemental: Final: Yes Yes Report Status: Submitted Create Date: 08/27/2010 1. Operator's OPS-issued Operator Identification Number (OPID): 11169 2. Name of Operator ENBRIDGE ENERGY, LIMITED PARTNERSHIP 3. Address of Operator: 3a. Street Address 1100 LOUISIANA, SUITE 3300 3b. City HOUSTON 3c. State Texas 3d. Zip Code 77002 4. Local time (24-hr clock) and date of the Accident: 07/28/2010 07:45 5. Location of Accident: Latitude: 47.372103 Longitude: -94.57539 6. National Response Center Report Number (if applicable): 949152 7. Local time (24-hr clock) and date of initial telephonic report to the National Response Center (if applicable): 07/28/2010 10:37 8. Commodity released: (select only one, based on predominant volume released) Crude Oil - Specify Commodity Subtype: - If "Other" Subtype, Describe: - If Biofuel/Alternative Fuel and Commodity Subtype is Ethanol Blend, then % Ethanol Blend: %: - If Biofuel/Alternative Fuel and Commodity Subtype is Biodiesel, then Biodiesel Blend (e.g. B2, B20, B100): B 9. Estimated volume of commodity released unintentionally (Barrels): .23 10. Estimated volume of intentional and/or controlled release/blowdown (Barrels): 11. Estimated volume of commodity recovered (Barrels): .23 12. Were there fatalities? No - If Yes, specify the number in each category: 12a. Operator employees 12b. Contractor employees working for the Operator 12c. Non-Operator emergency responders 12d. Workers working on the right-of-way, but NOT associated with this Operator 12e. General public 12f. Total fatalities (sum of above) 13. Were there injuries requiring inpatient hospitalization? No - If Yes, specify the number in each category: 13a. Operator employees 13b. Contractor employees working for the Operator 13c. Non-Operator emergency responders Page 1 of 14 Page 1 of 14#

Page 9Appendix C - Operator's Report 13d. Workers working on the right-of-way, but NOT associated with this Operator 13e. General public 13f. Total injuries (sum of above) 14. Was the pipeline/facility shut down due to the Accident? Yes - If No, Explain: - If Yes, complete Questions 14a and 14b: (use local time, 24-hr clock) 14a. Local time and date of shutdown: 07/28/2010 08:00 14b. Local time pipeline/facility restarted: 07/28/2010 17:45 - Still shut down? (* Supplemental Report Required) 15. Did the commodity ignite? No 16. Did the commodity explode? No 17. Number of general public evacuated: 18. Time sequence (use local time, 24-hour clock): 18a. Local time Operator identified Accident: 07/28/2010 07:45 18b. Local time Operator resources arrived on site: 07/28/2010 07:55 PART B - ADDITIONAL LOCATION INFORMATION 1. Was the origin of Accident onshore? Yes If Yes, Complete Questions (2-12) If No, Complete Questions (13-15) - If Onshore: 2. State: Minnesota 3. Zip Code: 56633 4. City Cass Lake 5. County or Parish Cass 6. Operator-designated location: Milepost/Valve Station Specify: 958.33 7. Pipeline/Facility name: Line 1 8. Segment name/ID: Valve at MP 958.33 9. Was Accident on Federal land, other than the Outer Continental Shelf (OCS)? No 10. Location of Accident: Pipeline Right-of-way 11. Area of Accident (as found): Underground Specify: Under soil - If Other, Describe: Depth-of-Cover (in): 6 12. Did Accident occur in a crossing? No - If Yes, specify below: - If Bridge crossing – Cased/ Uncased: - If Railroad crossing – Cased/ Uncased/ Bored/drilled - If Road crossing – Cased/ Uncased/ Bored/drilled - If Water crossing – Cased/ Uncased - Name of body of water, if commonly known: - Approx. water depth (ft) at the point of the Accident: - Select: - If Offshore: 13. Approximate water depth (ft) at the point of the Accident: 14. Origin of Accident: - In State waters - Specify: - State: - Area: - Block/Tract #: - Nearest County/Parish: - On the Outer Continental Shelf (OCS) - Specify: - Area: - Block #: 15. Area of Accident: PART C - ADDITIONAL FACILITY INFORMATION 1. Is the pipeline or facility: Interstate 2. Part of system involved in Accident: Onshore Pipeline, Including Valve Sites - If Onshore Breakout Tank or Storage Vessel, Including Attached Appurtenances, specify: 3. Item involved in Accident: Valve Page 2 of 14 Page 2 of 14#

Page 10Appendix C - Operator's Report - If Pipe, specify: 3a. Nominal diameter of pipe (in): 3b. Wall thickness (in): 3c. SMYS (Specified Minimum Yield Strength) of pipe (psi): 3d. Pipe specification: 3e. Pipe Seam , specify: - If Other, Describe: 3f. Pipe manufacturer: 3g. Year of manufacture: 3h. Pipeline coating type at point of Accident, specify: - If Other, Describe: - If Weld, including heat-affected zone, specify: - If Other, Describe: - If Valve, specify: Mainline - If Mainline, specify: Gate - If Other, Describe: 3i. Manufactured by: M & J 3j. Year of manufacture: 1951 - If Tank/Vessel, specify: - If Other - Describe: - If Other, describe: 4. Year item involved in Accident was installed: 1951 5. Material involved in Accident: Material other than Carbon Steel - If Material other than Carbon Steel, specify: Valve Stem Packing 6. Type of Accident Involved: Leak - If Mechanical Puncture – Specify Approx. size: in. (axial) by in. (circumferential) - If Leak - Select Type: Seal or Packing - If Other, Describe: - If Rupture - Select Orientation: - If Other, Describe: Approx. size: in. (widest opening) by in. (length circumferentially or axially) - If Other – Describe: PART D - ADDITIONAL CONSEQUENCE INFORMATION 1. Wildlife impact: No 1a. If Yes, specify all that apply: - Fish/aquatic - Birds - Terrestrial 2. Soil contamination: Yes 3. Long term impact assessment performed or planned: No 4. Anticipated remediation: No 4a. If Yes, specify all that apply: - Surface water - Groundwater - Soil - Vegetation - Wildlife 5. Water contamination: No 5a. If Yes, specify all that apply: - Ocean/Seawater - Surface - Groundwater - Drinking water: (Select one or both) - Private Well - Public Water Intake 5b. Estimated amount released in or reaching water (Barrels): 5c. Name of body of water, if commonly known: 6. At the location of this Accident, had the pipeline segment or facility been identified as one that "could affect" a High Consequence Area (HCA) as determined in the Operator's Integrity Management Program? No 7. Did the released commodity reach or occur in one or more High Consequence Area (HCA)? No 7a. If Yes, specify HCA type(s): (Select all that apply) - Commercially Navigable Waterway: Was this HCA identified in the "could affect" Page 3 of 14 Page 3 of 14#

Page 11Appendix C - Operator's Report determination for this Accident site in the Operator's Integrity Management Program? - High Population Area: Was this HCA identified in the "could affect" determination for this Accident site in the Operator's Integrity Management Program? - Other Populated Area Was this HCA identified in the "could affect" determination for this Accident site in the Operator's Integrity Management Program? - Unusually Sensitive Area (USA) - Drinking Water Was this HCA identified in the "could affect" determination for this Accident site in the Operator's Integrity Management Program? - Unusually Sensitive Area (USA) - Ecological Was this HCA identified in the "could affect" determination for this Accident site in the Operator's Integrity Management Program? 8. Estimated cost to Operator : 8a. Estimated cost of public and non-Operator private property damage paid/reimbursed by the Operator $ 8b. Estimated cost of commodity lost $ 8c. Estimated cost of Operator's property damage & repairs $ 8d. Estimated cost of Operator's emergency response $ 3,500 8e. Estimated cost of Operator's environmental remediation $ 14,852 8f. Estimated other costs $ Describe: 8g. Estimated total costs (sum of above) $ 18,352 PART E - ADDITIONAL OPERATING INFORMATION 1. Estimated pressure at the point and time of the Accident (psig): 393.00 2. Maximum Operating Pressure (MOP) at the point and time of the Accident (psig): 837.00 3. Describe the pressure on the system or facility relating to the Accident (psig): Pressure did not exceed MOP 4. Not including pressure reductions required by PHMSA regulations (such as for repairs and pipe movement), was the system or facility relating to the Accident operating under an established pressure restriction with pressure limits below those normally allowed by the MOP? No - If Yes, Complete 4.a and 4.b below: 4a. Did the pressure exceed this established pressure restriction? 4b. Was this pressure restriction mandated by PHMSA or the State? 5. Was "Onshore Pipeline, Including Valve Sites" OR "Offshore Pipeline, Including Riser and Riser Bend" selected in PART C, Question 2? Yes - If Yes - (Complete 5a. – 5f. below) 5a. Type of upstream valve used to initially isolate release source: Remotely Controlled 5b. Type of downstream valve used to initially isolate release source: Remotely Controlled 5c. Length of segment isolated between valves (ft): 171,758 5d. Is the pipeline configured to accommodate internal inspection tools? Yes - If No, Which physical features limit tool accommodation? (select all that apply) - Changes in line pipe diameter - Presence of unsuitable mainline valves - Tight or mitered pipe bends - Other passage restrictions (i.e. unbarred tee's, projecting instrumentation, etc.) - Extra thick pipe wall (applicable only for magnetic flux leakage internal inspection tools) - Other - - If Other, Describe: 5e. For this pipeline, are there operational factors which significantly complicate the execution of an internal inspection tool run? No - If Yes, Which operational factors complicate execution? (select all that apply) - Excessive debris or scale, wax, or other wall buildup Page 4 of 14 Page 4 of 14#

Page 12Appendix C - Operator's Report - Low operating pressure(s) - Low flow or absence of flow - Incompatible commodity - Other - - If Other, Describe: 5f. Function of pipeline system: > 20% SMYS Regulated Trunkline/Transmission 6. Was a Supervisory Control and Data Acquisition (SCADA)-based system in place on the pipeline or facility involved in the Accident? Yes If Yes - 6a. Was it operating at the time of the Accident? Yes 6b. Was it fully functional at the time of the Accident? Yes 6c. Did SCADA-based information (such as alarm(s), alert(s), event(s), and/or volume calculations) assist with the detection of the Accident? No 6d. Did SCADA-based information (such as alarm(s), alert(s), event(s), and/or volume calculations) assist with the confirmation of the Accident? No 7. Was a CPM leak detection system in place on the pipeline or facility involved in the Accident? No - If Yes: 7a. Was it operating at the time of the Accident? 7b. Was it fully functional at the time of the Accident? 7c. Did CPM leak detection system information (such as alarm(s), alert(s), event(s), and/or volume calculations) assist with the detection of the Accident? 7d. Did CPM leak detection system information (such as alarm(s), alert(s), event(s), and/or volume calculations) assist with the confirmation of the Accident? 8. How was the Accident initially identified for the Operator? Local Operating Personnel, including contractors - If Other, Specify: 8a. If "Controller", "Local Operating Personnel", including contractors", "Air Patrol", or "Guard Patrol by Operator or its contractor" is selected in Question 8, specify the following: Operator employee 9. Was an investigation initiated into whether or not the controller(s) or control room issues were the cause of or a contr buting factor to the Accident? No, the Operator did not find that an investigation of the controller(s) actions or control room issues was necessary due to: (provide an explanation for why the Operator did not investigate) - If No, the Operator did not find that an investigation of the controller(s) actions or control room issues was necessary due to: (provide an explanation for why the operator did not investigate) Controller would not be able to detect or control such a small release of product initiated from a valve stem packing. - If Yes, specify investigation result(s): (select all that apply) - Investigation reviewed work schedule rotations, continuous hours of service (while working for the Operator), and other factors associated with fatigue - Investigation did NOT review work schedule rotations, continuous hours of service (while working for the Operator), and other factors associated with fatigue Provide an explanation for why not: - Investigation identified no control room issues - Investigation identified no controller issues - Investigation identified incorrect controller action or controller error - Investigation identified that fatigue may have affected the controller(s) involved or impacted the involved controller(s) response - Investigation identified incorrect procedures - Investigation identified incorrect control room equipment operation - Investigation identified maintenance activities that affected control room operations, procedures, and/or controller response - Investigation identified areas other than those above: Describe: PART F - DRUG & ALCOHOL TESTING INFORMATION 1. As a result of this Accident, were any Operator employees tested under the post-accident drug and alcohol testing requirements of DOT's Drug & Alcohol Testing regulations? No - If Yes: 1a. Specify how many were tested: 1b. Specify how many failed: Page 5 of 14 Page 5 of 14#

Page 13Appendix C - Operator's Report 2. As a result of this Accident, were any Operator contractor employees tested under the post-accident drug and alcohol testing requirements of DOT's Drug & Alcohol Testing regulations? No - If Yes: 2a. Specify how many were tested: 2b. Specify how many failed: PART G – APPARENT CAUSE Select only one box from PART G in shaded column on left representing the APPARENT Cause of the Accident, and answer the questions on the right. Describe secondary, contributing or root causes of the Accident in the narrative (PART H). Apparent Cause: G6 - Equipment Failure G1 - Corrosion Failure - only one sub-cause can be picked from shaded left-hand column Corrosion Failure – Sub Cause: - If External Corrosion: 1. Results of visual examination: - If Other, Describe: 2. Type of corrosion: (select all that apply) - Galvanic - Atmospheric - Stray Current - Microbiological - Selective Seam - Other: - If Other, Describe: 3. The type(s) of corrosion selected in Question 2 is based on the following: (select all that apply) - Field examination - Determined by metallurgical analysis - Other: - If Other, Describe: 4. Was the failed item buried under the ground? - If Yes : 4a. Was failed item considered to be under cathodic protection at the time of the Accident? If Yes - Year protection started: 4b. Was shielding, tenting, or disbonding of coating evident at the point of the Accident? 4c. Has one or more Cathodic Protection Survey been conducted at the point of the Accident? If "Yes, CP Annual Survey" – Most recent year conducted: If "Yes, Close Interval Survey" – Most recent year conducted: If "Yes, Other CP Survey" – Most recent year conducted: - If No: 4d. Was the failed item externally coated or painted? 5. Was there observable damage to the coating or paint in the vicinity of the corrosion? - If Internal Corrosion: 6. Results of visual examination: - Other: 7. Type of corrosion (select all that apply): - - Corrosive Commodity - Water drop-out/Acid - Microbiological - Erosion - Other: - If Other, Describe: 8. The cause(s) of corrosion selected in Question 7 is based on the following (select all that apply): - - Field examination - Determined by metallurgical analysis - Other: - If Other, Describe: 9. Location of corrosion (select all that apply): - - Low point in pipe - E bow - Other: - If Other, Describe: 10. Was the commodity treated with corrosion inhibitors or biocides? Page 6 of 14 Page 6 of 14#

Page 14Appendix C - Operator's Report 11. Was the interior coated or lined with protective coating? 12. Were cleaning/dewatering pigs (or other operations) routinely utilized? 13. Were corrosion coupons routinely utilized? Complete the following if any Corrosion Failure sub-cause is selected AND the "Item Involved in Accident" (from PART C, Question 3) is Tank/Vessel. 14. List the year of the most recent inspections: 14a. API Std 653 Out-of-Service Inspection - No Out-of-Service Inspection completed 14b. API Std 653 In-Service Inspection - No In-Service Inspection completed Complete the following if any Corrosion Failure sub-cause is selected AND the "Item Involved in Accident" (from PART C, Question 3) is Pipe or Weld. 15. Has one or more internal inspection tool collected data at the point of the Accident? 15a. If Yes, for each tool used, select type of internal inspection tool and indicate most recent year run: - - Magnetic Flux Leakage Tool Most recent year: - Ultrasonic Most recent year: - Geometry Most recent year: - Caliper Most recent year: - Crack Most recent year: - Hard Spot Most recent year: - Combination Tool Most recent year: - Transverse Field/Triaxial Most recent year: - Other Most recent year: Describe: 16. Has one or more hydrotest or other pressure test been conducted since original construction at the point of the Accident? If Yes - Most recent year tested: Test pressure: 17. Has one or more Direct Assessment been conducted on this segment? - If Yes, and an investigative dig was conducted at the point of the Accident:: Most recent year conducted: - If Yes, but the point of the Accident was not identified as a dig site: Most recent year conducted: 18. Has one or more non-destructive examination been conducted at the point of the Accident since January 1, 2002? 18a. If Yes, for each examination conducted since January 1, 2002, select type of non-destructive examination and indicate most recent year the examination was conducted: - Radiography Most recent year conducted: - Guided Wave Ultrasonic Most recent year conducted: - Handheld Ultrasonic Tool Most recent year conducted: - Wet Magnetic Particle Test Most recent year conducted: - Dry Magnetic Particle Test Most recent year conducted: - Other Most recent year conducted: Describe: G2 - Natural Force Damage - only one sub-cause can be picked from shaded left-handed column Natural Force Damage – Sub-Cause: - If Earth Movement, NOT due to Heavy Rains/Floods: 1. Specify: - If Other, Descr be: - If Heavy Rains/Floods: Page 7 of 14 Page 7 of 14#

Page 15Appendix C - Operator's Report 2. Specify: - If Other, Descr be: - If Lightning: 3. Specify: - If Temperature: 4. Specify: - If Other, Descr be: - If High Winds: - If Other Natural Force Damage: 5. Describe: Complete the following if any Natural Force Damage sub-cause is selected. 6. Were the natural forces causing the Accident generated in conjunction with an extreme weather event? 6a. If Yes, specify: (select all that apply) - Hurricane - Tropical Storm - Tornado - Other - If Other, Descr be: G3 - Excavation Damage - only one sub-cause can be picked from shaded left-hand column Excavation Damage – Sub-Cause: - If Excavation Damage by Operator (First Party): - If Excavation Damage by Operator's Contractor (Second Party): - If Excavation Damage by Third Party: - If Previous Damage due to Excavation Activity: Complete Questions 1-5 ONLY IF the "Item Involved in Accident" (from PART C, Question 3) is Pipe or Weld. 1. Has one or more internal inspection tool collected data at the point of the Accident? 1a. If Yes, for each tool used, select type of internal inspection tool and indicate most recent year run: - - Magnetic Flux Leakage Most recent year conducted: - Ultrasonic Most recent year conducted: - Geometry Most recent year conducted: - Caliper Most recent year conducted: - Crack Most recent year conducted: - Hard Spot Most recent year conducted: - Combination Tool Most recent year conducted: - Transverse Field/Triaxial Most recent year conducted: - Other Most recent year conducted: Descr be: 2. Do you have reason to believe that the internal inspection was completed BEFORE the damage was sustained? 3. Has one or more hydrotest or other pressure test been conducted since original construction at the point of the Accident? - If Yes: Most recent year tested: Test pressure (psig): 4. Has one or more Direct Assessment been conducted on the pipeline segment? - If Yes, and an investigative dig was conducted at the point of the Accident: Most recent year conducted: - If Yes, but the point of the Accident was not identified as a dig site: Most recent year conducted: 5. Has one or more non-destructive examination been conducted at the point of the Accident since January 1, 2002? Page 8 of 14 Page 8 of 14#

Page 16Appendix C - Operator's Report 5a. If Yes, for each examination, conducted since January 1, 2002, select type of non-destructive examination and indicate most recent year the examination was conducted: - Radiography Most recent year conducted: - Guided Wave Ultrasonic Most recent year conducted: - Handheld Ultrasonic Tool Most recent year conducted: - Wet Magnetic Particle Test Most recent year conducted: - Dry Magnetic Particle Test Most recent year conducted: - Other Most recent year conducted: Descr be: Complete the following if Excavation Damage by Third Party is selected as the sub-cause. 6. Did the operator get prior notification of the excavation activity? 6a. If Yes, Notification received from: (select all that apply) - - One-Call System - Excavator - Contractor - Landowner Complete the following mandatory CGA-DIRT Program questions if any Excavation Damage sub-cause is selected. 7. Do you want PHMSA to upload the following information to CGA- DIRT (www.cga-dirt.com)? 8. Right-of-Way where event occurred: (select all that apply) - - Public - If "Public", Specify: - Private - If "Private", Specify: - Pipeline Property/Easement - Power/Transmission Line - Railroad - Dedicated Public Utility Easement - Federal Land - Data not collected - Unknown/Other 9. Type of excavator: 10. Type of excavation equipment: 11. Type of work performed: 12. Was the One-Call Center notified? 12a. If Yes, specify ticket number: 12b. If this is a State where more than a single One-Call Center exists, list the name of the One-Call Center notified: 13. Type of Locator: 14. Were facility locate marks visible in the area of excavation? 15. Were facilities marked correctly? 16. Did the damage cause an interruption in service? 16a. If Yes, specify duration of the interruption (hours) 17. Description of the CGA-DIRT Root Cause (select only the one predominant first level CGA-DIRT Root Cause and then, where available as a choice, the one predominant second level CGA-DIRT Root Cause as well): Root Cause: - If One-Call Notification Practices Not Sufficient, specify: - If Locating Practices Not Sufficient, specify: - If Excavation Practices Not Sufficient, specify: - If Other/None of the Above, explain: G4 - Other Outside Force Damage - only one sub-cause can be selected from the shaded left-hand column Other Outside Force Damage – Sub-Cause: - If Nearby Industrial, Man-made, or Other Fire/Explosion as Primary Cause of Incident: - If Damage by Car, Truck, or Other Motorized Vehicle/Equipment NOT Engaged in Excavation: 1. Vehicle/Equipment operated by: - If Damage by Boats, Barges, Drilling Rigs, or Other Maritime Equipment or Vessels Set Adrift or Which Have Otherwise Lost Their Mooring: 2. Select one or more of the following IF an extreme weather event was a factor: - Hurricane Page 9 of 14 Page 9 of 14#

Page 17Appendix C - Operator's Report - Tropical Storm - Tornado - Heavy Rains/Flood - Other - If Other, Descr be: - If Routine or Normal Fishing or Other Maritime Activity NOT Engaged in Excavation: - If Electrical Arcing from Other Equipment or Facility: - If Previous Mechanical Damage NOT Related to Excavation: Complete Questions 3-7 ONLY IF the "Item Involved in Accident" (from PART C, Question 3) is Pipe or Weld. 3. Has one or more internal inspection tool collected data at the point of the Accident? 3a. If Yes, for each tool used, select type of internal inspection tool and indicate most recent year run: - Magnetic Flux Leakage Most recent year conducted: - Ultrasonic Most recent year conducted: - Geometry Most recent year conducted: - Caliper Most recent year conducted: - Crack Most recent year conducted: - Hard Spot Most recent year conducted: - Combination Tool Most recent year conducted: - Transverse Field/Triaxial Most recent year conducted: - Other Most recent year conducted: Describe: 4. Do you have reason to believe that the internal inspection was completed BEFORE the damage was sustained? 5. Has one or more hydrotest or other pressure test been conducted since original construction at the point of the Accident? - If Yes: Most recent year tested: Test pressure (psig): 6. Has one or more Direct Assessment been conducted on the pipeline segment? - If Yes, and an investigative dig was conducted at the point of the Accident: Most recent year conducted: - If Yes, but the point of the Accident was not identified as a dig site: Most recent year conducted: 7. Has one or more non-destructive examination been conducted at the point of the Accident since January 1, 2002? 7a. If Yes, for each examination conducted since January 1, 2002, select type of non-destructive examination and indicate most recent year the examination was conducted: - Radiography Most recent year conducted: - Guided Wave Ultrasonic Most recent year conducted: - Handheld Ultrasonic Tool Most recent year conducted: - Wet Magnetic Particle Test Most recent year conducted: - Dry Magnetic Particle Test Most recent year conducted: - Other Most recent year conducted: Describe: - If Intentional Damage: 8. Specify: - If Other, Descr be: - If Other Outside Force Damage: 9. Describe: G5 - Material Failure of Pipe or Weld - only one sub-cause can be selected from the shaded left-hand column Page 10 of 14 Page 10 of 14#

Page 18Appendix C - Operator's Report Use this section to report material failures ONLY IF the "Item Involved in Accident" (from PART C, Question 3) is "Pipe" or "Weld." Material Failure of Pipe or Weld – Sub-Cause: 1. The sub-cause selected below is based on the following: (select all that apply) - Field Examination - Determined by Metallurgical Analysis - Other Analysis - If "Other Analysis", Descr be: - Sub-cause is Tentative or Suspected; Still Under Investigation (Supplemental Report required) - If Construction, Installation, or Fabrication-related: 2. List contributing factors: (select all that apply) - Fatigue or Vibration-related Specify: - If Other, Descr be: - Mechanical Stress: - Other - If Other, Descr be: - If Original Manufacturing-related (NOT girth weld or other welds formed in the field): 2. List contributing factors: (select all that apply) - Fatigue or Vibration-related: Specify: - If Other, Descr be: - Mechanical Stress: - Other - If Other, Descr be: - If Environmental Cracking-related: 3. Specify: - Other - Describe: Complete the following if any Material Failure of Pipe or Weld sub-cause is selected. 4. Additional factors: (select all that apply): - Dent - Gouge - Pipe Bend - Arc Burn - Crack - Lack of Fusion - Lamination - Buckle - Wrinkle - Misalignment - Burnt Steel - Other: - If Other, Describe: 5. Has one or more internal inspection tool collected data at the point of the Accident? 5a. If Yes, for each tool used, select type of internal inspection tool and indicate most recent year run: - Magnetic Flux Leakage Most recent year run: - Ultrasonic Most recent year run: - Geometry Most recent year run: - Caliper Most recent year run: - Crack Most recent year run: - Hard Spot Most recent year run: - Combination Tool Most recent year run: - Transverse Field/Triaxial Most recent year run: - Other Most recent year run: Describe: 6. Has one or more hydrotest or other pressure test been conducted since original construction at the point of the Accident? Page 11 of 14 Page 11 of 14#

Page 19Appendix C - Operator's Report - If Yes: Most recent year tested: Test pressure (psig): 7. Has one or more Direct Assessment been conducted on the pipeline segment? - If Yes, and an investigative dig was conducted at the point of the Accident - Most recent year conducted: - If Yes, but the point of the Accident was not identified as a dig site - Most recent year conducted: 8. Has one or more non-destructive examination(s) been conducted at the point of the Accident since January 1, 2002? 8a. If Yes, for each examination conducted since January 1, 2002, select type of non-destructive examination and indicate most recent year the examination was conducted: - - Radiography Most recent year conducted: - Guided Wave Ultrasonic Most recent year conducted: - Handheld Ultrasonic Tool Most recent year conducted: - Wet Magnetic Particle Test Most recent year conducted: - Dry Magnetic Particle Test Most recent year conducted: - Other Most recent year conducted: Descr be: G6 – Equipment Failure - only one sub-cause can be selected from the shaded left-hand column Equipment Failure – Sub-Cause: Non-threaded Connection Failure - If Malfunction of Control/Relief Equipment: 1. Specify: (select all that apply) - - Control Valve - Instrumentation - SCADA - Communications - Block Valve - Check Valve - Relief Valve - Power Failure - Stopple/Control Fitting - ESD System Failure - Other - If Other – Descr be: - If Pump or Pump-related Equipment: 2. Specify: - If Other – Descr be: - If Threaded Connection/Coupling Failure: 3. Specify: - If Other – Descr be: - If Non-threaded Connection Failure: 4. Specify: Seal (NOT pump seal) or packing - If Other – Descr be: - If Defective or Loose Tubing or Fitting: - If Failure of Equipment Body (except Pump), Tank Plate, or other Material: - If Other Equipment Failure: 5. Describe: Complete the following if any Equipment Failure sub-cause is selected. 6. Additional factors that contributed to the equipment failure: (select all that apply) - Excessive vibration - Overpressurization - No support or loss of support - Manufacturing defect - Loss of electricity - Improper installation Page 12 of 14 Page 12 of 14#

Page 20Appendix C - Operator's Report - Mismatched items (different manufacturer for tubing and tubing fittings) - Dissimilar metals - Breakdown of soft goods due to compat bility issues with transported commodity - Valve vault or valve can contributed to the release - Alarm/status failure - Misalignment - Thermal stress - Other Yes - If Other, Describe: Stem nut seal - normal wear. G7 - Incorrect Operation - only one sub-cause can be selected from the shaded left-hand column Incorrect Operation – Sub-Cause: - If Damage by Operator or Operator's Contractor NOT Related to Excavation and NOT due to Motorized Vehicle/Equipment Damage: - If Tank, Vessel, or Sump/Separator Allowed or Caused to Overfill or Overflow: 1. Specify: - If Other, Descr be: - If Valve Left or Placed in Wrong Position, but NOT Resulting in a Tank, Vessel, or Sump/Separator Overflow or Facility Overpressure: - If Pipeline or Equipment Overpressured: - If Equipment Not Installed Properly: - If Wrong Equipment Specified or Installed: - If Other Incorrect Operation: 2. Descr be: Complete the following if any Incorrect Operation sub-cause is selected. 3. Was this Accident related to (select all that apply): - - Inadequate procedure - No procedure established - Failure to follow procedure - Other: - If Other, Descr be: 4. What category type was the activity that caused the Accident? 5. Was the task(s) that led to the Accident identified as a covered task in your Operator Qualification Program? 5a. If Yes, were the individuals performing the task(s) qualified for the task(s)? G8 - Other Accident Cause - only one sub-cause can be selected from the shaded left-hand column Other Accident Cause – Sub-Cause: - If Miscellaneous: 1. Descr be: - If Unknown: 2. Specify: PART H - NARRATIVE DESCRIPTION OF THE ACCIDENT Enbridge field laborers working along the right-of-way reported seeing evidence of oil on the ground around a mainline valve at MP-958.33, which is located north of Hwy 2 on the East side of Cass Lake. The laborers contacted their Supervisor who confirmed the release and mobilized Enbridge response. Lines 1 and 2 in this route were shut down and valves on either side of the location isolated the section as a precaution. The Pipeline Maintenance Supervisor, who responded to the site, confirmed the valve leak on Line 1 and es imated a small amount of oil had been released on the ground around the valve. Enbridge maintenance personnel excavated, by hand, the soil around the site, evaluated the valve condition and confirmed that he valve stem packing was leaking. Enbridge maintenance personnel were able to make on site repairs to he valve stem packing. Estimated volume released was 10 gallons. Once the packing was repaired, the line was restarted at 17:45 PM local time. All affected soil has been removed and disposed at an appropriate off-site facility. The incident was reported to the MN Duty Officer and the National Response Center. A representative from MNOPS visited to inspect he site. File Full Name Page 13 of 14 Page 13 of 14#

Page 21Appendix C - Operator's Report File Full Name PART I - PREPARER AND AUTHORIZED SIGNATURE Preparer's Name Theresa Picton Preparer's Title Compliance Analyst Preparer's Telephone Number 715-394-1468 Preparer's E-mail Address theresa.picton@enbridge.com Preparer's Facsimile Number 832-325-5477 Authorized Signature's Name David Hoffman Authorized Signature Title Supervisor Pipeline Safety Compliance Authorized Signature Telephone Number 715-394-1540 Authorized Signature Email david.hoffman@enbridge.com Date 08/27/2010 Page 14 of 14 Page 14 of 14#

Page 22Appendix D - Interstate Agent PIM Page 1 of 3#

Page 23Appendix D - Interstate Agent PIM Page 2 of 3#

Page 24Appendix D - Interstate Agent PIM Page 3 of 3#