Updated September 8, 2010
The San Mateo County Environmental Health Department has deemed the water suitable for human contact. Water testing shows that there is no longer any danger of contamination from the sewage discharge on August 25th or fuel or oil from the small plane crash on September 2nd.
Redwood City is removing its advisary concerning contact with water in the Redwood Shores lagoon, and citizens can resume recreational use of the water. The city apologies for any inconveniences that these unfortunate events have caused, and thanks you for your understanding.
Update from September 2, 2010
General Overview:
- On 9/1/10 lagoon water was treated with bactericide (GreenClean Pro) – use of this material is approved by the Regional Water Quality Control Board
- Latest water test results will be available late Thursday/early Friday
- The City is maintaining its advisory for residents to avoid any contact with the lagoon water – however, the City’s goal is to work with County Environmental Health to remove the water advisory by this weekend.
- Lagoon water dissolved oxygen level is at normal
- Revised estimated quantity of discharge: 48,000 gallons (unchanged since last update).
- Cleanup of impacted garages and site is nearing completion.
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 showed high levels of coliform bacteria including E.coli. The City advises 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. 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.
On 9/1/10 lagoon water was treated with bactericide (GreenClean Pro). The use of this material is approved by the Regional Water Quality Control Board. The latest water test results will be available late Thursday/early Friday. The lagoon water dissolved oxygen level is at normal, which is a positive indicator. The City’s goal is to work with County Environmental Health to remove the water advisory by this weekend
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 complete. Final cleanup and restoration of the parking area and the site of the pipeline failure is in process.
Update from August 27, 2010
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. The repair was largely completed Thursday night (September 26) at approximately 10 pm.
Crews will be working over the weekend and into next week to clean up the affected garages where raw sewage spilled from the broken pipeline, and to restore the parking area and landscaping affected by the pipeline failure and repair work.
The City has no further information at this time on the total quantity of sewage that was released, pending analysis of the pump station records. The original quantity of 5,000 gallons, as reported to the San Francisco Regional Water Quality Control Board (SFRWQCB), was an initial estimate only due to their requirement that a spill notification must be made within two hours of the spill, including a preliminary estimate. It’s expected that the actual quantity will be significantly higher.
As expected, initial testing of the lagoon water shows high levels of coliform bacteria including E.coli. The City strongly advises 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. This advisory is in place indefinitely. The City will notify Redwood Shores resident 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 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. This is not a situation involving any airborne elements.
The contamination remains contained within the lagoon, and the city is working with remediation experts and in consultation with the Water Quality Control Board to explore environmentally safe options for how best to address the contamination.
Previous news release/background:
Wednesday, August 25 at around 3 pm a sewer force main (pressurized pipeline) ruptured in the area of Davit Lane and Anchor Circle in the Redwood Shores area of Redwood City. The pressure of the line caused the asphalt to buckle, and raw sewage was dispersed onto the surface. The material entered six nearby garages, and an uncertain amount went into the adjacent Redwood Shores lagoon.
Residents are advised to avoid any contact with the lagoon water until further notice – no swimming, boating, kayaking, or touching the water. Warning signs have been posted at beaches.
There are a series of valves, gates, and pumps to control water flow between the lagoon and the bay; with those, the City is preventing th exchange of water between the lagoon and the bay at this time.
Crews were on scene shortly after the failure and began work to identify and repair the break. Contractors were also brought on site, along with specialized cleanup crews. All appropriate regulatory agencies were notified. The City reported an estimated 5,000 gallons of sewage spilled into the lagoon, but that number is an estimate only and is subject to change once a more thorough analysis is performed.
Last night Redwood City made automated phone calls to those residents in Redwood Shores who’s numbers are in the City’s CodeRED emergency notification system. Residents were advised that they should avoid any contact with the lagoon water until further notice. The information has also been posted on the City’s website and was covered by television media news crews.
As of Thursday at noon, the pipeline had been excavated and the break uncovered, and pumping is continuing to allow crews to fully access the rupture for repair. In the meantime the sewage flow is continually being pumped into tanker trucks and transported to the nearby sewage treatment plant. Currently no further sewage is spilling into the lagoon or into nearby garages.
At this time the City does not have an estimate of when the break will be fully repaired. The City will make additional automated phone calls to update the residents in Redwood Shores and remind them to avoid any contact with the lagoon water, and will notify residents when the water has returned to normal conditions.
Redwood City residents wishing to register their phone number to be notified of emergencies in their areas can go to www.redwoodcity.org, pull down the “I want to…” menu and select “Register for Emergency Notification”