At Clallam County PUD, reliability of electrical infrastructure is centerstage when making maintenance and upgrade decisions. Like utilities everywhere, we face the question of overhead versus underground power lines, a choice that becomes particularly relevant when storms roll into our county. Our mission is to provide reliable, efficient, safe, and low-cost utility services in a financially and environmentally responsible manner.
Clallam PUD’s electrical infrastructure is comprised of 110 miles of transmission lines, 686 miles of primary overhead distribution lines and 1,157 miles of primary underground distribution lines. We maintain an additional 114 miles of secondary overhead lines and 177 miles of secondary underground lines. As it can be seen, a substantial portion of our electrical distribution infrastructure is underground. While undergrounding all power lines may seem like an ideal solution, a balanced perspective is crucial.
The economic advantage of overhead lines is significant. Installation and maintenance costs of overhead lines are considerably less than underground systems. Given the diverse economic landscape of the peninsula, the lower upfront and ongoing costs of overhead lines are crucial for ratepayers in Clallam County. Being a public utility, the PUD is required to pass costs onto ratepayers. Large-scale undergrounding projects which are not suitable to the terrain could significantly increase rates for residents and businesses across the county. Parts of Clallam County feature rocky subsoil and areas with high water tables. These geographical conditions can make underground installation complex and costly, or even infeasible in certain locations. The recent supply chain issues have disproportionately driven underground project costs higher compared to overhead projects. For example, the materials cost (poles, pole framing assembly, and conductor) for installation of 1,000 feet of overhead infrastructure at current cost is $15,497 compared to underground infrastructure material cost (conduit, cable, splice vault) at $77,778! Installation cost varies with terrain and accessibility.
Overhead lines can be installed more rapidly. Quick installation minimizes disruption and can be crucial for expanding or upgrading infrastructure efficiently. While underground lines reduce outage frequency, when outages do occur, repairs could be particularly challenging and time-consuming. Locating faults in buried lines, especially in wet or snowy conditions, can be difficult, potentially leading to longer restoration times, even if outages are less frequent overall. Visible lines allow our crews to quickly locate and repair damage, leading to faster power restoration after weather-related outages.
Trenching and excavation for underground lines can have environmental impacts, including soil disturbance and potential effects on local ecosystems and a key consideration in determining underground installation in Clallam County.
It is undeniable that overhead lines are exposed to strong winds, heavy rainfall, occasional snow, and potential coastal storms. These conditions lead to fallen trees, downed lines, and power outages, making weather-related reliability a concern for overhead systems in our region. But overhead lines offer versatility. They can be adapted to the varied terrains found in our County, making them a cost-effective and practical solution for power delivery across the diverse geography.
While safety is at center stage with everything we do at the PUD, with a mix of residential areas and interface with forested lands, the wildfire risks associated with overhead lines, such as contact with trees or accidental contact, are relevant considerations. Underground lines, though significantly expensive, not only provide a superior advantage in terms of reliability during the storm season, but also reduces risks from downed wires, pole-related accidents, and wildfire risks. Undergrounding lines results in reduced maintenance cost required for ongoing vegetation management.
It is for these reasons, the decision between overhead and underground electrical utilities requires careful consideration of unique context in every project area. While undergrounding offers compelling advantages in terms of reliability during stormy weather, the significant cost implications and logistical challenges cannot be ignored. These decisions are made with careful consideration specific needs of the area, budget realities, and environmental regulations. At the PUD, we take a balanced approach, involving targeted undergrounding in critical areas, combined with robust maintenance and upgrades of existing overhead infrastructure to ensure reliable, and affordable power for all residents and businesses in the county. For example, the PUD has planned to convert several overhead sections to underground on Diamond Point, while plans are being made to replace wood transmission poles to fiberglass poles to improve resiliency.
