West Point treatment plant ill-prepared for growing Seattle region, says post-flood report

The West Point sewage-treatment plant, the region’s largest, is ill-prepared to handle an emergency during heavy rains, a contractor hired to investigate a catastrophic flood at the plant last winter has found.

The contractor, AECOM, reported: The plant lacks redundant treatment capacity and backup systems; workers don’t have proper training to manage an emergency such as the flood that swamped the plant; and the new, $40 million automated control system fully implemented just days before the flood actually made managing the emergency worse.

The computerized system is intended to monitor operations throughout the plant to alert managers in control rooms to anything amiss. Instead, as the flooding disaster unfolded, the system overwhelmed them. “The shift supervisor was faced with more than 2,100 alarms in less than one hour and it was not clear which were critical and which were of lesser significance,” the report states.

Yet during the flood, the alarm system also provided no automatic alert to the disaster itself. Managers didn’t know flooding had occurred until they saw it, and then had to eventually manually turn off pumps still surging sewage into the crippled plant.

The West Point plant’s lack of adequate backup systems, the contractor found, includes automatic backup power to effluent pumps. A power outage at the pumps began the cascade of events that led to the flood. The cause of the outage still has not been determined.

Lack of backup systems and capacity at the plant made the risks during any high-flow event, such as a big winter rain, much greater.

“We are right at the ragged edge,” said Metropolitan King County Councilman Rod Dembowski during the briefing by the contractor. The study cost $418,700.

Such rains are not rare, occurring some 40 times a year. But the plant currently leaves little margin for error in a big-flow event if anything goes wrong, consultants warned. Workers also aren’t adequately trained or supported by the automated control system to manage the situation in an emergency.

The constraints on the plant, in terms of its size relative to the flows it routinely handles and the lack of redundancy and backup, were striking to the consultants, said Sujan Punyamurthula, senior vice president at AECOM and principal in charge of the review project.

“This is a particularly complex plant that has to run at peak flow. It makes it somewhat unique,” Punyamurthula said. “Most plants have backup systems that can handle outages. This one was particularly constrained and multiple failures could happen.”

The challenges to the plant will only get worse as the region’s population grows, more pavement replaces forests and green space, and climate change brings bigger rain events, the contractor found.

To be better prepared, the West Point plant near Discovery Park should — along with adding backup systems, redundancy and better training — also elevate its management practices, the consultant found.

Recommended operations are similar to the approach used in complex chemical plants, intended to help managers identify maintenance needs and other issues that have gone undetected at West Point.

Inexpensive float switches that signal water levels in the plant, long in need of replacement, were just one of the things that led to the disaster in February. The switches have since been replaced with new models that can be easily tested for proper operation, unlike the previous ones.

But equipment isn’t enough: Workers also need better guidance on when to bypass untreated sewage around the plant to an emergency outfall, and they need authority to make that decision in an emergency, the contractor found. The plant itself is the last line of defense to prevent pollution of Puget Sound and must be protected, the consultant said. Damage from the flood put West Point out of normal operation for three months, violating state and federal water-quality standards.

The plant was repaired and has been operating properly since mid-May.

The Feb. 9 flood led to an estimated $57 million in damage and dumped 235 million gallons of untreated wastewater, including 30 million gallons of raw sewage, from an emergency outfall near the beach at Seattle’s Discovery Park.

Tuesday morning, AECOM presented its findings and recommendations to the County Council’s Transportation, Economy and Environment Committee.

A Seattle Times investigation discovered similar problems, highlighting errors in judgment, poor communication, a lack of training, equipment failures and faulty maintenance that caused the flood.

In the past, West Point has had trouble with equipment, including the float switch. The ball on a rod is supposed to alert operators with a high-water-level alarm, which can trigger an automatic bypass to the emergency outfall, preventing flooding. But on Feb. 9 the float switches jammed, and that had happened before, according to plant records and consultant reports.

AECOM interviewed employees and gathered operations and maintenance records and incident reports to determine how to avoid another failure.

If the disaster had occurred during the day, wastewater managers said, people would have been seriously injured or killed. Managers said they were lucky no one died. One employee injured her leg during a harrowing escape as a torrent of water filled rooms, walkways and stairwells.

Christie True, director of the county Department of Natural Resources and Parks, which manages wastewater treatment, said the department agrees with the report’s findings, and already is at work implementing some of its recommendations, including training for employees.

The department has added a second power supply to the valves and pumps that failed in the disaster. In the future, during wet-weather events, an electrician will be on hand at the plant, and staff will walk the facility to watch for flooding and proper function of key equipment, such as the float switches, True said.

Other issues raised in the report will be part of a review of the county’s wastewater treatment system and its preparedness for the next 50 years that also was ordered by the council in response to the flood.

The state Department of Ecology will review the contractor’s report before determining any fines for violating the plant’s wastewater permit, said Jessica Payne, communications manager for Ecology.

The long-term effects to the environment remain unknown.

The cost of the flood is still being calculated, but most of it will be covered by the county’s insurance plans.