Oroville Spillways Phase 2 Update Late March 2018
Channel: Lisa & Richard Ray
Date: 2018-08-13

After the spillway collapse and evacuation, the Federal Emergency Regulatory Commission (FERC) ordered the DWR to put together a team of independent analysts to assess the damage to the dam, how the emergency happened and what steps should be taken next. Meanwhile, the DWR also put together a separate team of independent consultants.

Experts have already identified many factors that may have led to the collapse of the spillway. For example, the spillway was built on top of weak, porous soil, according to reporting by Water Deeply, which likely eroded during the wettest water year in recorded history for Northern California.

In the first independent report by DWR’s consultants, they pointed to both damage and design failures in the main spillway that would prevent the state from completing repairs before the beginning of the rainy season in November. The study directly contradicted the official DWR report, which stated that repairs could be completed by then.

State and federal officials subsequently kept another two independent reports secret, citing security risks and terrorism risks. However, public outcry prompted officials to eventually release another five redacted versions. Many documents related to the incident remain secret, including documents about asbestos that may have been released by the dam, and the risk to the public.

Like the initial report, the redacted reports detailed the extensive structural damage and failures from the crisis. Similarly, on May 5, the FERC investigators released a preliminary memo that detailed 24 factors that potentially led to the spillway collapse.

According to Martin McCann, Jr., the director of the National Performance of Dams Project at Stanford University, Oroville may have been an institutional failure as well as a structural one. Problems with the dam-building industry not paying attention to data on dam safety and structure, bad communication between groups – like engineers and geologists – and a failure to catch the signs of impending failures during routine inspections, all contributed to the Oroville Dam incident. They may point to a much larger problem.

The Sacramento Bee reported that California is borrowing $500 million from the federal government to pay for the Oroville Dam repairs, including $274 million that was previously approved by President Donald Trump to respond to the crisis. Currently, work is underway to repair the damaged spillway – just dredging the spillway debris has cost the state more than $22 million, and Kiewit Corporation won the contract to repair the spillway for $275 million, according to the Bee. The state has deployed helicopters and drones to assess the extent of the damage, and engineers in Utah even built a working, scale model of the spillway to better assess how water flows over the damaged concrete, and how best to repair it.

You can access ongoing, updated documents about the Oroville Dam on the DWR’s website or stayed tuned to Water Deeply’s Oroville Dam coverage.