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Redwood City Thanks Residents for Patience During Sewage Spill
Reply
Redwood City would like to thank Redwood Shores residents for their patience during the unfortunate discharge of raw sewage into the lagoon on August 25th and the resulting temporary advisory against recreational use of the water.
As most readers will recall, at around 3 pm on that day a pressurized sewer pipeline ruptured near Davit Lane and Anchor Circle. Raw sewage was discharged onto the surface, entering six nearby garages and flowing into the adjacent lagoon.
City crews were on the scene shortly after the pipeline failure and began work to identify and repair the break. Contractors and specialized cleanup crews were also on site, and all appropriate regulatory agencies were notified. Through the City’s automated CodeRED emergency phone notification system and warning signs posted at beaches, along with extensive media coverage, residents were advised to avoid any contact with the lagoon water. Through a series of valves, gates, and pumps the City prevented the exchange of water between the lagoon and the bay.
After first expecting that the failure was from a broken valve, it turned out that instead the break was actually in a section of pipeline, which required a more extensive and lengthy repair process. During the time it took to repair the break, the sewage flow was continually being pumped into tanker trucks and transported to the nearby sewage treatment plant pump station.
Initially, the City reported a spill of 5,000 gallons which was an estimate put forth within the Two-Hour Notification time period required by the San Francisco Bay Regional Water Quality Control Board. That initial estimate was, by necessity, made while the spill was still in progress. Once the spill was stopped and upon further analysis of all the data, the City reported a revised calculated estimate of 48,000 gallons.
Subsequent testing of the lagoon water showed high levels of coliform bacteria including E.coli, and so the City continued its advisory to avoid any contact with the lagoon water. Several more CodeRED phone calls were made to residents to keep them apprised of the situation.
On September 1, the lagoon water was treated with a bactericide, with concurrence by the Regional Water Quality Control Board. Further testing was showing some improvement in the water quality, likely in combination with sunlight breaking down the material, and natural bacterial die-off.
However on September 2, just before the Labor Day weekend, the tragic crash of a small plane into the diamond basin area of the lagoon further complicated the City’s ability to re-open the lagoon to public use, since there was concern with the potential for fuel and oil in the water. Further, the Federal Aviation Administration and other authorities became involved, thereby precluding the City from making an independent decision at that time on reopening the lagoon.
On September 7 the San Mateo County Environmental Health Department informed Redwood City that the water quality in the Redwood Shores lagoons was safe for normal human contact. The next day, the City removed its advisory concerning contact with the water, and informed residents that they could resume normal recreational activities in the Redwood Shores lagoon.
The City’s investigation into the cause of the pipeline break is still underway, and no conclusions have yet been reached. It’s important to let residents know that the City does have an extensive preventative maintenance schedule for the entire sewer system involving regular, frequent inspection of pump station systems, in addition to 24/7 automated remote monitoring.
This unfortunate set of circumstances is a reminder of how important it is for residents to register their phone numbers to be notified of emergencies in their neighborhood. Please be sure to go to www.redwoodcity.org/codered to sign up, or update your contact information.
Redwood Shores Lagoon Sewage Notice
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.
Redwood Shores Lagoon Sewage Spill
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”
Dredging Update for March 2010
Many of you have seen the dredging taking place in the main lagoon areas — Redwood City thanks you all for your ongoing patience! Unfortunately, the contractor has come across a significant amount of debris in the lagoon, such as old rebar (metal), pieces of concrete, and hundreds of golf balls, This required him to stop work to remove this debris, which has slowed down the operation. Dredging in the main lagoon area (primarily around Shorebird Island) is now expected to be completed by the end of April.
A second phase of dredging is scheduled to start by early April, in the lagoon between Sandpiper Lagoon Subdivision No. 1 and Bridgeport Subdivision. Work will take place on weekdays only, through the end of April, and the machinery in the lagoon will operate between 8 am and 4:30 pm. Sediment will be loaded into trucks (not every day; only when sufficient amounts have been stockpiled for removal) and hauled out for re-use or disposal. To accomplish this, the outer eastbound lane of Redwood Shores Parkway will be closed to traffic for a segment between Avocet Drive to Egret Lane between 9 am and 2:30 pm daily; access to Waterside Circle and Bay Harbour Drive will be maintained.
Dredging Update for February 2010
This update is to let you know that the project will not be completed by the originally-expected date of January 31, 2010. Unfortunately, the contractor is uncovering some unforeseen conditions that have slowed the work progress. As they’ve been working, the contractor has discovered old rebar (metal), pieces of concrete, and even hundreds of golf balls in the lagoon. Because the contractor has to stop work and remove this debris, this has slowed down their operation.
The City has received approval from the U.S. Army Corps of Engineers and the Regional Water Quality Control Board to continue the work past the original end date, subject to certain restrictions (avoiding “ground disturbing activities”). Assuming that the contractor does not run into any further significant unforeseen debris in the lagoons, they anticipate the work to be completed by the end of February, 2010. This work will be focused on the lagoon around Shorebird Island (dredging zones 3, 4, and 5).
Please visit www.redwoodcity.org/shoresdredging for information about this project, or to be added to the email list.
For immediate concerns with ongoing work, contact the contractor, Lance Dohman, at 650-868-8240. For questions about the overall project, please call Brian Lee, Redwood City Supervisory Civil Engineer, at 650-780-7391.
Again, thank you for your understanding as we continue with the dredging project, which will result in a cleaner, more appealing lagoon in Redwood Shores.
Informational Meeting Scheduled:
Redwood City is proposing to build a small concrete boat ramp at the end of Davit Lane, at the far end of Shannon Park. This ramp will be for City use only, in order to provide access for a small barge that cuts and collects widgeon weed for lagoon maintenance, as well as access for debris removal and for small craft for water testing. Currently, because there is no viable boat access to the lagoon east of Shell Boulevard, very little maintenance takes place in that area. Consequently, the widgeon grass is rampant, and water quality is poor. This access ramp will allow for regular maintenance in that part of the lagoon, and will improve water quality and appearance. The ramp will be fenced with the same style of fencing that is currently in place along the shoreline, and will be accessed through a locked gate.
In order to provide interested members of the Redwood Shores community with full information about the City’s selection of this particular site for a maintenance access boat ramp, the Redwood Shores Community Association is hosting a community information meeting. At this meeting, the City will present an overview of the research into possible locations, the rationale for selection of this site, and the precise elements of the ramp and maintenance activities. Staff will also be prepared to answer questions or concerns that any resident may have about this proposal.
The meeting is scheduled for Tuesday, January 26th at 7 pm in the Community Room of the Redwood Shores Library, 949 Marine Parkway.
Dredging On Saturday
Just a note to let you know that the City has given the dredging contractor permission to work Saturdays from 8 am — 4 pm throughout January. It turns out that this adjustment is necessary in order maintain the schedule for completion. Additionally, the contractor is utilizing up to two additional “aquamog” pump barges to accelerate the work.
Dredging Update
The dredging will continue until December 18 – dredging will begin in the lagoon closest to Area H, north of Marine Parkway only (Zone 9A)
*Over the next two weeks, the contractor will be installing the floating pipeline that will be used to pump dredge material later from the lagoons around Shorebird Island (Zones 3,4,5) to Area H.
*By mid-December, the contractor will place a booster pump on a small barge, in the main lagoon approximately halfway between Shorebird Island and Area H.
*During the last week of December, and continuing through mid-January, the contractor will be dredging the lagoons around Shorebird Island.
*During January the contractor will complete remaining areas – portions of the lagoon near Area H, but south of Marine Parkway (Zones 8 and 9).
*By January 31, the contractor should be complete, and cleanup/demobilization of equipment will take place.
And as a reminder, the work hours will be 7:30 am – 4:00 pm, weekdays only. Boaters need to be very aware of the floating pipeline, which will be well-marked. While it’s in place, it will not be possible for boats to cross over the pipeline, as it will be only partially submerged. This may be a particular issue for residents living on parts of Shorebird Island, and along the northern side of the main lagoon, during the period while the Shorebird Island area is being dredged. Once Shorebird Island lagoon is dredged, the pipeline will be removed and boats will have access. The contractor will have floating buoys and markers attached to the pipeline to clearly indicate its location.
Lagoon Dredging Update
In October, the City Council approved a contract with the firm Aquatic Environments to perform dredging in certain lagoons at Redwood Shores. This work will help specified areas of the lagoon to better “flush” and therefore improve water quality and appearance (please see www.redwoodcity.org/shoresdredging ).
As part of the outreach to affected residents, in addition to a direct mail flyer and an article in last month’s Pilot, the Redwood Shores Community Association and Redwood City hosted a project community information meeting on Thursday, October 22, 2009, during which residents heard from and asked questions of City staff, contractors, and consultants. At that meeting, staff provided an overview of the project, outlined the scope of work, and presented a tentative schedule. Here is a brief overview:
* The two areas to be dredged are the lagoon around Shorebird Island, and portions of the lagoon near Area H between Laguna Pointe and California Harbor Court.
* It’s expected that the contractor will begin prep work the first week of November, and start actual dredging a bit later in the month (a more specific schedule will be available on the project website in November).
* The work hours will be 7:30 am – 4:00 pm, weekdays only.
* While the contractor has up to 180 days to complete the work, it’s expected that the dredging will be completed by January 31st.
* Dredging will be done with one or two small barges which will hydraulically pump the sediment from the lagoon floor, sending it through a pipeline running along the main lagoon, to be deposited into Area H as part of the wetland restoration.
The key issues raised by residents attending the meeting, and summaries of staff responses, were:
* The expected noise levels of the dredge machinery and booster pump.
Some level of noise is unavoidable, but it is temporary. The contractor estimates that the noise of the pumps is similar to a mid-sized pickup truck engine. The expected noise level is approximately 80-85 decibels at 20 feet distance from the machinery. The machinery utilizes mufflers and is enclosed to minimize noise. We ask for residents’ patience throughout this project.
* Inability to launch boats from certain areas while the temporary pipeline is in place.
While it’s in place, it will not be possible for boats to cross over the pipeline, as it will be only partially submerged. This may be a particular issue for residents living on parts of Shorebird Island, and along the northern side of the main lagoon, for about a month while the Shorebird Island area is being dredged. Once Shorebird Island lagoon is dredged, the pipeline will be removed and boats will have easy access. The contractor will have floating buoys and markers attached to the pipeline to clearly indicate its location.
* There will only be partial dredging in the lagoon between Laguna Pointe and California Harbor Court.
Some parts of this lagoon contain the compound PAH (polycyclic aromatic hydrocarbons – likely from roadway runoff) in levels higher than is allowed for use as wetland restoration fill. Such sediment would have to be mechanically dredged and trucked to an alternate disposal site, at a significantly higher expense than disposal in Area H. Because of this higher expense, it is not financially feasible at this time for the City to dredge those portions of this lagoon – therefore only specified sections of this lagoon will be dredged. The City’s intent is to determine a way to finance the complete dredging of this area at a later date, once funds are fully available, likely several years away.
Much more information and diagrams are online at the City’s project website at www.redwoodcity.org/shoresdredging. There, you can also sign up to receive periodic updates via email.
The City and its contractor wish to thank the Redwood Shores community for its patience and understanding as this lagoon dredging project gets underway – the result will be an improved lagoon that more positively contributes to the beauty and pride of Redwood Shores, as well as the quality of life of its residents.