A blowout in 2017 of the spillway below the highest dam in the U.S., the Oroville Dam on the Feather River, that forced the evacuation of 180,000 people led the Federal Energy Regulatory Commission to adopt rules this week to increase dam safety across the country. Independent consultants are to perform in-depth inspections at Oroville and thousands of other dams.
“This addresses one of the Commission’s most important jobs, safety,” said Commissioner Willie Phillips at his first FERC meeting. He declined to vote on this or other issues at the Dec. 16 meeting citing insufficient time to fully understand the many issues on the commission’s December agenda.
In February 2017, a warm atmospheric river melted an unusual amount of Sierra snow at once, deluging Lake Oroville and leading to massive water flows down the reservoir’s main and emergency spillways. The spillways eroded under the heavy flow, putting the infrastructure and the people below in jeopardy. The California Department of Water Resources is responsible for the Oroville spillways and dam.
Oroville was not the only recent hazard or failure at a U.S. dam. Last May, heavy rain and floodwaters led to the collapse of two private dams in Michigan, threatening up 41,000 people in the communities below.
There are more than 90,000 dams across the country, half more than 50 years old. More than 10,000 are designated high hazard, Commission Chair Rick Glick said at the agency’s final meeting of 2021. The cost to upgrade these systems is estimated at $20 billion, and not all are under FERC’s jurisdiction.
Under the new rules, there is to be a two-tier inspection of dams by independent consultants every five years that alternate between an in-depth and less comprehensive or “periodic” inspection.
According to FERC staff, periodic inspections will focus on the performance of the project over the previous five years, including a field inspection and data review.
The Comprehensive Assessment is “a deep dive into every aspect of a project, including a detailed review of the design basis, analyses of record and construction history, and an evaluation of spillway adequacy.”
The rules also update public safety incident reporting and require some dam owners to develop public safety plans. At the same time, it released new engineering guidelines.
FERC staff will next hold a technical conference on the costs of compliance and how to balance them against safety needs. The conference is tentatively set for April.
Commissioner Alison Clements noted the importance of “balancing safety against what is possible for dam operators.
Source of the photo: Association of State Dam Safety Officials