Investigation Into Water Reclamation Plant Accident Proceeds

The investigation into the May 10 accident at the water reclamation plant in Spokane, Wash., is proceeding, with cleanup of Digester No. 3, where the accident occurred, nearing completion.

"While we're still months away from completing this investigation, we think it's important to provide an update to the citizens on what we have accomplished and what lies ahead," says Deputy Mayor Jack Lynch, who is leading the team assigned with this work. "This is a painstaking process; we must be thorough—for the safety of our employees and our community."

Since the City outlined its investigation process in late May, a number of things have occurred:

* All the sludge has been removed from the tank, and now the remainder of the digester's cement dome is being removed from the bottom of the tank;

* The Spokane Fire Department completed its initial data collection related to the accident;

* Exponent, the forensic engineering firm hired by the City to investigate the incident, has reviewed the Fire Department's data, conducted interviews, and reviewed technical readings and many other documents. Since the cleanup of the tank took longer than anticipated, Exponent's ability to examine the inside of the tank and the dome was delayed until last week. Exponent is now analyzing massive amounts of data and information. Exponent hopes to report its findings by early September;

* The Mayor's Oversight Committee is proceeding with its work. The members have conferred with City staff to obtain updates on the investigation, reviewed documents, and familiarized themselves with the basic operations of the plant and the digester. Each member has been assigned to monitor specific issues such as document review, the City's insurance coverage, the L & I investigation, the work being done by Exponent, and issues related to the design and operation of the digester. It has monitored the progress of the City's investigation to date and will continue its work until the investigation has been completed;

* The City is continuing to cooperate with the Washington State Department of Labor & Industries as L & I proceeds with its own investigation; and

* The City quickly implemented a couple of new procedures at the plant to help ensure the safety of workers in light of the tank failure. The procedures include operating the remaining digesters with lower levels of product and restricting access to the top of the digesters.

The cause of the accident is still unknown, but initial evaluations indicate that the two operating digesters are safe. The plant’s digesters process solids, using anaerobic bacteria that break down or "digest" organic material in the absence of oxygen. It’s possible that the City may be able to use digester No. 3 for storage of completely processed solids this winter when frozen ground can limit the ability to incorporate the treated materials into farm fields.

A fourth digester had been in the initial planning stage before the May 10 incident. The City is proceeding with its preliminary plans to design and build that fourth digester, and details about those plans will be presented to the public in the next few weeks.

Source: AP