20230509AVU to Staff 158.pdf

AVISTA CORPORATION RESPONSE TO REQUEST FOR INFORMATION

JURISDICTION: IDAHO DATE PREPARED: 05/09/2023 CASE NO: AVU-E-23-01 / AVU-G-23-01 WITNESS: David Howell REQUESTER: IPUC RESPONDER: David James TYPE: Production Request DEPARTMENT: Wildfire Resiliency
REQUEST NO.: Staff-158 Supplemental TELEPHONE: [phone] REQUEST: Please describe any occurrences where the Company undergrounded any distribution lines both
inside and outside of the scope of the WRP. a. If any, please provide a supporting work. RESPONSE:
Of the 419 feeder miles hardened under the Wildfire Resiliency Program in Idaho and
Washington, 3.2 miles or .7% was converted from overhead service to underground. 5.4 miles are currently in design with a plan to be converted in 2023. All miles constructed and currently in planning have fallen within the project guidelines.
SUPPLEMENTAL 05/09/2023 In Avista 2023 Wildfire Resiliency Plan, the Distribution Grid Hardening program has completed 392 miles of line upgrades from 2020 through the end of 2029. Of that mileage only, 12 miles
(3.1%) were converted from overhead powerlines to underground cables. The decision to convert a line segment from overhead to underground is based on a multitude of factors including the overall asset health of the facility, reliability performance, line accessible issues, environmental and construction challenges together with project costs, and the availability of resources. While experts agree, that undergrounding (conversion) of existing overhead facilities represents the
ultimate with respect to fire ignition mitigation, the costs and challenges to convert existing overhead lines are often a significant obstacle. Excavation in developed areas involves careful consideration of existing UG facilities including water, sewer, irrigation, telecom, and natural gas lines. Converting overhead lines in developed areas can present serious disruptions to commercial businesses and to homeowners. While converting facilities to underground is only done on a
case-by-case basis as part of the Distribution Grid Hardening program, new construction to connect new businesses and homes to the electric grid generally involves underground electric facilities.
Data from 2016 through 2021 indicates that 483.93 miles of new underground facilities were
constructed. The vast majority of these facilities involved customer-requested facilities (new hook-ups) such as subdivision development and retail business construction. Over that same time frame, nearly 120 miles of overhead lines were decommissioned or replaced with underground facilities.
Also, District Managers, Operations Engineers, and Construction Project Coordinators (line designers) are asked to use underground cables and equipment when installing new facilities in high-fire threat areas. In general, this aligns with the Company’s strategy to install underground
systems for development projects but we are reinforcing messaging to avoid adding overhead lines
in high fire threat areas.
RECEIVED
Tuesday, May 9, 2023 12:22:12 PM
IDAHO PUBLIC
UTILITIES COMMISSION
As part of the Investment & Infrastructure Jobs Act, Avista has applied for a $50 million dollar
federal grant aimed at converting approximately 200 miles of existing overhead lines in areas that
are: 1. Included in the WUI Tier 2 or Tier 3 areas (high fire-threat areas). 2. Identified as underserved or overburdened as identified by the federal governments as
Justice 40 areas. 3. Customers that experience upwards of 10 to 15 unplanned electric outages per year (excessive outage rate). Avista is active in the Western Energy Institutes – Overhead & Underground Distribution
Subcommittee. One of the standing questions addressed by that committee is whether utilities have initiated a formal overhead lines conversion program. While some utilities have conducted limited pilot projects, no utility has an active overhead conversion program. Although, Pacific Gas & Electric has announced that it plans to convert 10,000 miles of overhead lines in high-fire threat districts to underground facilities.
Please see Staff_PR_158 Supplemental Attachment A attached that details the OH and UG mileage for the period 2016 - 2021. See Staff_PR_158 Supplemental Attachment B for underground plant additions (net of retirements) by Business Case and plant location, for accounts
357, 358, 366, and 367 (transmission and distribution underground conduit and conductor) for the
period 2021-2022. Note the data is also segregated between “Not WRP” and “WRP” for ease of review.