Alliance Pipeline Inc. — Pipeline Safety Interpretation

Page 1PI-01-0115 U.S. Department of Transportation Research and Special Programs Administration September 5, 2001 Mr. Rick Gulstad Compliance Engineer Alliance Pipeline Inc. 6385 Old Shady Oak Road, Suite 150 Eden Prairie, MN 55344 Dear Mr. Gulstad: This is in response to your enclosed letter of May 29, 2001, requesting an interpretation of the pipeline odorization requirements in 49 CFR § 192.625. You note that Alliance currently odorizes gas for compressors station uses, but would prefer to use only gas detectors to increase the level of safety at unmanned stations. Gas detectors would allow for round- the-clock monitoring for gas leaks at the stations. The odorization requirements at § 192.625 of the pipeline safety regulations only require odorization of gas in a transmission facility in a Class 3 or 4 location. Alliance's compressor stations are all in Class 1 or 2 locations. Therefore, odorization of gas at these compressor stations, even for domestic uses, is not required. In addition, it is clear that monitored gas detectors at such locations will provide a higher level of safety. In short, the pipeline safety regulations do not require Alliance to odorize gas in its compressor station facilities, as long as they are not in a Class 3 or 4 areas. If you need further assistance, please call me at (202) 366-4565. Sincerely yours, Richard D. Huriaux, P.E. Manager, Regulations Office of Pipeline Safety#

Page 2Alliance Pipeline Inc. 6385 Old Shady oak Road Suite 150 Eden Prairie, MN 55344 May 31, 2001 Mr. Richard D. Huriaux Regulations Manager Office of Pipeline Safety 400 Seventh Street, S.W. Room 7128 Washington, D.C. 20590-0001 Dear Huriaux: Alliance Pipeline L.P. (Alliance) formally requests an interpretation of the requirements for odorization of natural gas under § 192.625. The regulation is unclear whether odorization would be required for the intended usage of domestic natural gas at Alliance's compressor station facilities. Alliance currently odorizes natural gas from its transmission pipeline for compressor station domestic use but would prefer to use only gas detectors in lieu of odorizing the natural gas. We feel the changes proposed would increase the level of safety at our compressor stations that are designed to operate in an "un-manned" fashion. The installation of additional gas detectors and associated control systems would allow for 7 days a week and 24 hours per day monitoring of the facility and would initiate an alarm of the facility in the event of a minor leak whether or not personnel were present. Odorized natural gas is currently used within the utility building at Alliance compressor stations for the following: • Boiler fuel to raise the temperature of glycol that flows through piping to supply heat to the fuel gas building, utility building, and main compressor building • Boiler fuel to heat glycol which in turn is used to heat fuel gas supplied to the compressor units • Auxiliary power unit (APU) fuel Electric heat is used to heat the Alliance working quarter’s area. The hot water heater and all cooking equipment are electric equipment. The main compressor building and the fuel gas building are self enclosed buildings that are more than 80 feet away from the utility building and are not connected in any fashion to the utility building. The utility building, working quarters, and MCC building are all under one roof but are partitioned off by walls. In addition to the gas detectors that are currently located in the compressor building and fuel gas building, Alliance proposes to install gas detectors in the utility building that would sound an alarm at a concentration of gas in air of 20% of the lower explosive level for natural gas and would start a vent fan. Also, the supply of natural gas to the utility building would be shut off. Once the alarm is sounded, an Alliance personnel "call out” would be required to investigate. Alliance believes that the proposed gas detection alarm system in the utility building provides as great or a greater level of safety than odorization of the gas would provide. The gas detection system would not be depending on the ability of human intervention (ie-smell) to recognize the potential of a gas leak. Sincerely, Rick Gulstad Compliance Engineer#