The City is working with the San Mateo County Environmental Health Department and its consultants on options for treating the sewage in the lagoon in an environmentally-friendly manner. It’s known that sunlight will cause natural degradation of the sewage and it will dilute. Human fecal material is not harmful to the wildlife in the lagoon. This is not a situation involving any airborne elements.

Update: Redwood City Sewage Spill August 27

The broken sewer pipeline in the Redwood Shores area of Redwood City has been repaired and reconnected, and is in operation. Testing has taken place and the pipeline is stable. City crews will continue to monitor the pipeline and pump system to ensure that it is operating properly.

Overview:

• Revised estimated quantity of discharge: 48,000 gallons
• Water testing of the lagoon continues to show high levels of E.coli
• The City maintaining its advisory for residents to avoid any contact with the lagoon water
• The City is working with County Environmental Health and specialized consultants on remediation plan for lagoon water
• Cleanup of impacted garages and site is largely complete

Detail:

The City must notify the San Francisco Regional Water Quality Control Board (SFRWQCB) within two hours of becoming aware of a sewage spill into the bay. Within three working days of the initial notification, the City must provide an updated report with current data.

Upon becoming aware of the sewer line failure in the Redwood Shores area of Redwood City last Wednesday afternoon, the City immediately complied with the two-hour notification requirement. The City also notified the Office of Emergency Services and San Mateo County Environmental Health Services.

In that initial notification we provided a preliminary estimate of the number of gallons believed to be involved in the spill. At that time, the City estimated that 300 gallons per minute were being released and that the discharge could be stopped within 20 — 30 minutes. Staff calculated that this would result in an estimated discharge of about 5,000 gallons. Upon further investigation, staff anticipated that this number was likely to increase significantly as the discharge continued well beyond the initial expected stop time. The initial work was focused on what staff expected would be a valve failure; however, upon excavation (which took several hours) it was discovered this was a pipeline break resulting in a far greater amount of discharge. This increase in discharge took place since exposure and excavation of a pipeline is a much more extensive and time consuming repair than for a valve.

On Monday August 30, City staff filed an uncertified initial report to the California Integrated Water Quality System (the State Water Resources Board) with a calculated discharge amount of 48,000 gallons.

Testing of the lagoon water at various locations within the main lagoon shows high levels of coliform bacteria including E.coli. The City continues to strongly advise the community to avoid any contact with the lagoon water ? do not swim, boat, kayak, or otherwise touch the water, and do not let pets have any contact with the water.ÿ This advisory is in place indefinitely, and Redwood Shores residents will be informed as soon as it’s determined the lagoon water has returned to a normal condition.

The City is working with the San Mateo County Environmental Health Department, the Water Quality Control Board and the City’s consultants on options to improve lagoon water quality in an environmentally-friendly manner. Although sunlight and other natural processes will cause natural degradation of some elements of the sewage, the city is actively evaluating alternative methods to accelerate lagoon water quality improvement. It is not known when implementation of lagoon cleanup measures will take place.

Implementation of lagoon cleanup measures is expected to begin by the middle of this week. This is not a situation involving any airborne elements. The city is monitoring for impacts on fish and water fowl, and has found no evidence of any injury to animals in the lagoon. We continue to monitor lagoon conditions daily while we work to restore water quality.

Cleanup of the six residential garages is largely complete. Final cleanup and restoration of the parking area and the site of the pipeline failure will take place this week.