20031030Final Order No 29368.pdf

Office of the Secretary
Service Date
October 30, 2003
BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION
IN THE MATTER OF THE WAIVER REQUEST)
FILED BY A VISTA UTILITIES FOR AN
EXEMPTION FROM THE COMMISSION'
SAFETY RULE 201, IDAP A 31.11.01.201.
CASE NO. AVU-03-
ORDER NO. 29368
On October 14, 2003, Avista Utilities filed a letter requesting a waiver from the
Commission s Safety Rule 201 , ID AP A 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. ~ 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 specific waiver to encase plastic gas pipe above ground where it
crosses a flver.
The Commission s Safety Rule 3 provides that any person may request a waiver from
any safety rule. IDAP A 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. IDAP A 31.01.01.053.
THE WAIVER REQUEST
A vista requests a waiver so that it may place a 6-inch polyethylene (PE) plastic pipe
above ground in a steel casing. The Company proposes to place the plastic pipe in a 10-inch
steel casing where the gas line crosses the South Fork of the Palouse River on u.S. 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. At the ends of the bridge, the plastic pipe will emerge from the steel encasement and will
be buried below ground level.
A vista s waiver request also included the following design information:
The Maximum Allowable Operating Pressure (MAOP) of this gas line is
60 pounds per square inch (gauge) (PSIG).
ORDER NO. 29368
The 10-inch steel casing will terminate below ground level on both sides of
the bridge.
The casing will be suspended from a new 67- foot length concrete bridge
(Idaho Transportation Department Project No. BR-4II0(l47)).
. A boot-type end seal will be used at both ends of the casing to positively
seal between the casing and gas carrier pipe.
Casing vent pipes will be installed to prevent the possible buildup of
pressure and to detect leakage of gasses.
Casing insulators (thinsulators) will be installed and spaced at a minimum
of 5 feet to provide positive separation between the casing and carrier pipe.
Casing pipe is housed under the open-girder bridge and consequently will
be shielded from the effects of direct sunlight.
The computed design pressure for the PE pipe (SDR 11.5) at 120 degrees
Fahrenheit is 61 PSIG; the highest recorded temperature for the area is 109
degrees Fahrenheit. Gas pressure within the pipe on the bridge will
therefore not exceed system MAOP due to ambient temperature.
The maximum thermal contraction of the PE pipe is calculated to be 13.
inches. Because the ends of the pipe are "fixed" by the burying of the
facility at the ends of the bridge, this contraction will be exhibited as
internal stresses. The internal stress is calculated to be 737 psi which is
less than the 1 000 psi hydrostatic design base (HDB) rating of the PE
pIpe.
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 the proposed location under the bridge, 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.
ORDER NO. 29368
Second, steel encased plastic pipe is less susceptible 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.
FINDINGS AND DISCUSSION
After reviewing the waiver request and Staff comments, we find it reasonable to grant
Avista a waiver of our Safety Rule 201 and more specifically, our adoption of 49 C.
~ 192.321(a). We find the measures Avista proposes to utilize to encase and protect the plastic
pipe above ground where it crosses the South Fork of the Palouse River are reasonable and
appropriate. Consequently, we find that it is appropriate to grant the requested waiver in this
instance.
Although we grant a WaIver, we recognize that the Commission must give the
Department of Transportation s Office of Pipeline Safety (OPS) written notice of the waiver at
least 60 days before this waiver is effective. 49 U.C. ~ 60118(d). Consequently, our Order
granting this waiver request shall not become effective until December 30, 2003, unless OPS
permits the waiver to become effective at an earlier date.
ORDER
IT IS HEREBY ORDERED that Avista Utilities' request for a waiver from the
Commission s Safety Rule 201 (IDAPA 31.11.01.201) and, more specifically 49 c.F.
~ 192.321(a), is granted as conditioned below.
IT IS FURTHER ORDERED that the Commission s Executive Administrator
forward a copy of Avista s request and our Order to the Office of Pipeline Safety (OPS) for its
revIew.
IT IS FURTHER ORDERED that this Order granting Avista a waiver shall not
become effective until December 30, 2003 , unless OPS authorizes this waiver to become
effective sooner.
THIS IS A FINAL ORDER. Any person interested in this Order (or in issues finally
decided by this Order) or in interlocutory Orders previously issued in this Case No. A VU-03-
may petition for reconsideration within twenty-one (21) days of the service date of this Order
with regard to any matter decided in this Order or in interlocutory Orders previously issued in
this Case No. A VU-03-Within seven (7) days after any person has petitioned for
ORDER NO. 29368
reconsideration, any other person may cross-petition for reconsideration. See Idaho Code ~ 61-
626.
DONE by Order of the Idaho Public Utilities Commission at Boise, Idaho this
-tt-.
day of October 2003.
PAUL
----
JJ~
MARSHA H. SMITH, COMMISSIONER
ATTEST:
t2() D. Jewell
C mmISSlOn Secretary
vldlO:A VUP0301 dh
ORDER NO. 29368