20031027_664.pdf

DECISION MEMORANDUM
TO:COMMISSIONER KJELLANDER
COMMISSIONER SMITH
COMMISSIONER HANSEN
COMMISSION SECRETARY
COMMISSION STAFF
FROM:DON HOWELL
DATE:OCTOBER 24, 2003
RE:VISTA UTILITIES' REQUEST FOR WAIVER FROM
COMMISSION'S SAFETY RULE 201, CASE NO. A VU-03-
THE
On October 14, 2003 , Avista Utilities filed a letter requesting a waiver from the
Commission s Safety Rule 201 IDAPA 31.11.01.201. Safety Rule 201 requires all gas
corporations to abide by federal safety regulations contained in the Code of Federal Regulations
including 49 C.R. 9 192.321(a). The U.S. Department of Transportation s safety standards in
Section 192.321(a) require that plastic pipe used to transport natural gas "must be installed below
ground level." Avista seeks a waiver to encase the plastic pipe above ground where it crosses the
nver.
The Commission s Safety Rule 3 provides that any person requesting a waiver from
any safety rule may seek a waiver from the Commission. IDAPA 31.11.01.003. A waiver
request must describe the specific waiver sought; refer to the particular rule or order that is
controlling; and state the facts to support the waiver request. IDAP A 31.01.01.053.
THE WAIVER REQUEST
Avista requests a waiver so that it may place a 6-inch plastic pipe above ground in a
steel casing. The Company proposes to place the plastic pipe in a 10-inch steel casing where the
main gas line crosses the South Fork of the Palouse River on US. Highway 95 in Moscow
Idaho. The Company proposes that the plastic pipe (encased in the steel casing) be suspended
from the concrete bridge as it spans the river for a distance of 67 feet. To further protect the
casing and plastic pipe from direct sunlight, the casing will be suspended under the bridge, thus
shielding it from direct sunlight. At the ends of the bridge, the plastic pipe will emerge from the
steel encasement and will be buried below ground level.
DECISION MEMORANDUM
STAFF COMMENTS
Staff believes that a waiver in this instance is warranted. The Company provided
calculations to the Staff showing that 10-inch roller hangers with adequate capacity would be
installed at 9.1 feet spacing along with the necessary hardware of adequate capacity. The
Company has assured Staff that prior to installing the plastic pipe in the casing, cleaning pigs
will be run through the casing to remove debris, which might damage the plastic pipe. The
Company indicates that in this location the pipe will be protected from ice and wind loads.
There are advantages to the use of encased plastic pipe at this bridge crossing. First
plastic pipe is not prone to corrosion, and therefore will require less maintenance than steel pipe.
Second, steel encased plastic pipe is less acceptable to damage from vandalism, airborne objects
and external loading. Finally, Staff notes that many similar waivers have been granted by the
various states and approved by the U.S. Department of Transportation, Office of Pipeline Safety.
COMMISSION DECISION
Given the specific facts of this case, does the Commission believe that a waiver from
49 C.R. 9 192.321(a) is warranted?
Vld/M:AVUPO31
DECISION MEMORANDUM