A202201 LOC Response.pdf

1411 E. Mission, PO Box 3727
Spokane, WA 99220-3727

Submitted to Jeff Brooks via electronic mail at [e-mail].

August 1, 2022

Mr. Jeff Brooks
Pipeline Safety Program Manager
Idaho Public Utilities Commission
11331 Chinden Blvd., Building 8, Suite 201-A
Boise, ID 83714

Re: IPUC Coeur d’Alene District Field Audit Letter of Concern – Avista Response

Dear Mr. Brooks:

In your letter of July 14, 2022, you listed an area of concern discovered during the 2022 Coeur
d’Alene District Field Audit that was conducted June 7-8, 2022. In this letter we have provided
a restatement of the area of concern and Avista’s response.

Area of Concern (AOC) Reference:

49 CFR §192.739(a)(2)(3)(4)

Description of AOC:

(a) Pressure limiting and regulating stations: Inspection and testing.

(2) Adequate from the standpoint of capacity and reliability of operation for the
service in which it is employed;
(3) Except as provided in paragraph (b) of this section, set to control or relieve at the
correct pressure consistent with the pressure limits of §192.201(a); and
(4) Properly installed and protected from dirt, liquids, or other conditions that might
prevent proper operation.

Finding(s):

Regulator stations 212, 4246, and 4247 had one or both regulators fail to lock up at the pre­
established set points. These failures were corrected on-site and at the time of failure.

Avista Response to AOC:

Avista has been actively and fervently working for many years to address the operational issues
resulting from Dithiazine fouling at company gate stations and regulator stations. During our
most recent Avista / IPUC Fireside Chat on 2/24/22, Gas Design Engineer Tim Harding made a
presentation (enclosed with this letter) to PUC Safety Staff on the topic of Dithiazine and what
Avista is doing to address the issue and minimize its effects.

Avista has a robust Dithiazine Monitoring and Surveillance Program as detailed in the following
three documents (enclosed as well to this letter).

• Continuing Surveillance for Dithiazine.pdf
• Dithiazine Monitoring-Step by Step.pdf
• Presentation in Continuing Surveillance.pdf

Dithiazine is addressed, as well, in Avista’s Distribution Integrity Management Program (DIMP)
Plan Document, Rev. 10, pages 247, 252, 262 and 302. The DIMP Plan document has
previously been sent to IPUC.

Avista will review the current maintenance schedule prescribed by the company’s Dithiazine
Mitigation Plan for regulator station 212, 4246 and 4247 and determine if a higher frequency of
maintenance over and above federal code requirements is required and implement such findings
as appropriate.

Avista is optimistic these efforts, in addition to the forthcoming pigging of affected interstate
pipelines, will serve to advance the reliability and public safety of our natural gas system.

Respectfully Submitted,

Jody Morehouse
Director, Natural Gas
JM/rkb

Enclosures

Cc: Brian Schultz, Manager, Gas Compliance and Integrity
Jeff Webb, Manager, Gas Design, Measurement and Planning
Michelle Heskett, Manager, Coeur d’Alene Gas Operations