Presentation on theme: "Mercer Island E. coli Event Bob James, ODW December 2014."— Presentation transcript:
Mercer Island E. coli Event Bob James, ODW December 2014
Today’s Talk Coliform Basics – the organism and the rule requirements Describe Mercer Island and the coliform event Explain the role of the health agencies Capture some lessons learned
Total Coliform Bacteria Total coliform bacteria are common in the environment (soil or vegetation) and are generally harmless. If a lab detects only total coliform bacteria in drinking water, the source is probably environmental and fecal contamination is unlikely. However, if environmental contamination can enter the system, pathogens could get in too. It is important to find and resolve the source of the contamination.
E. coli Bacteria E. coli is a subgroup of the total coliform group. Most E. coli bacteria are harmless and exist in the intestines of people and warm-blooded animals. However, some strains can cause illness. The presence of E. coli in a drinking water sample usually indicates recent fecal contamination. That means there is a greater risk that pathogens are present.
E. coli O157:H7 A specific strain of E. coli bacteria Causes most disease outbreaks. When a drinking water sample is reported as “E. coli present:” o It does not mean that O157:H7 is present. o It does indicate recent fecal contamination. o Boiling contaminated drinking water destroys all forms of E. coli, including O157:H7.
Coliform and Chlorine Disinfection with chlorine should provide 3-log inactivation of coliform bacteria in less than 2.5 minutes. The CT is 0.25 mg-min/L.
The Total Coliform Rule Purpose: Determine the adequacy of water treatment. Determine the integrity of the distribution system and its impact upon water quality.
The Total Coliform Rule Collect routine total coliform samples from the distribution system every month. Samples must be analyzed by an accredited laboratory for the presence of total coliform. Positive samples must be analyzed for E. coli. Three repeat samples must be collected for every positive routine total coliform sample. An acute MCL violation is created if two or more of the four samples contain total coliform and at least one of the samples contains E. coli. Public Notification is required in response to an acute MCL violation within 24 hours.
Mercer Island Facts Population: 22,270 People Service Connections: 7,335 (62 Food Service Permits) Source: Seattle Public Utilities (SPU) Storage: Two 4 MG Reservoirs Distribution System: o 121 Miles of Water Main o Significant Amount of Unlined Cast Iron o 86 PRV Vaults and stand alone Air-Vacuum Assemblies
Mercer Island Supply Facilities SPU Supply Lines Pumped Zone (492) Reservoir Zone (398) Pump Station 4 MG Reservoir By-pass Valve
Mercer Island Facts (cont.) Pump Stations: o Main PS (9,000 gpm to elevation 492) o First Hill PS (1,150 gpm to elevation 456) Pressure Zones: o Reservoir Zone – 398 (31.4% of total demand) o Pumped Zone – 492 (68.6% of total demand) o First Hill Zone – 456 (2.2% of total demand) o Many Smaller Zones Supplied Through PRVs (range 215 – 285 ft. HGL)
Mercer Island Pressure Zones
Mercer Island Coliform Monitoring Program Seattle Public Utilities Regional Coliform Monitoring Program SPU Collects All Routine Samples (> 880/month) On Mercer Island SPU collects 18/Month from Five Sample Stations Mercer Island Collects Repeats and Investigative Samples All Samples Are Analyzed By SPU’s Laboratory
Mercer Island Coliform Monitoring Sites
Mercer Island Timeline Wednesday - September 24 th Seattle collected 61 samples from Seattle and its wholesale customers Two of the 61 samples were collected from Mercer Island Five samples contained total coliform One of the Mercer Island samples contained E. coli
Collection Date: 9/24/2014 Results Reported: 9/26/2014 Total Coliform Absent Total Coliform Present and E. coli Present Mercer Island Coliform Results
Mercer Island Timeline Friday - September 26 th Seattle collects repeat samples from its distribution system Soos Creek collects repeat samples from its distribution system Mercer Island collects three repeat samples and six investigative samples from its distribution system SPU, Public Health – Seattle & King County, and DOH prepare a draft news release with help from Soos Creek and Mercer Island
Collection Date: 9/26/2014 Results Reported: 9/27/2014 Total Coliform Absent Total Coliform Present and E. coli Present Mercer Island Coliform Results 4
Mercer Island Timeline Saturday - September 27 th All repeat samples are satisfactory Four out of six investigative samples collected by Mercer Island contain E. coli Decision is made to issue a Health Advisory at 11:00 am Mercer Island collects eight more investigative samples and begins to monitor chlorine residual throughout the system News Release issued at 3:45 pm followed by a press conference at 4:30 pm Special Purpose Investigation conducted
DOH Special Purpose Investigation Certified Operator Interview o Pressure Events o New Construction o HPC Results and Chlorine Residual Measurements o Flushing o Operational Changes Reservoir Inspections o Vents o Overflows o Drainlines
Collection Date: 9/27/2014 Results Reported: 9/28/2014 Total Coliform Absent Total Coliform Present and E. coli ??? Mercer Island Coliform Results 4
Mercer Island Timeline Sunday - September 28 th One out of eight investigative samples contains total coliform No E. coli present in the sample at the 18-hour mark Mercer Island collects eleven investigative samples and continues to monitor chlorine residual and flush if necessary Health Advisory remains in effect
Collection Date: 9/28/2014 Results Reported: 9/29/2014 Total Coliform Absent Total Coliform Present and E. coli Absent Mercer Island Coliform Results 4
Mercer Island Timeline Monday - September 29 th One out of eleven investigative samples contains total coliform No E. coli present in any sample Mercer Island collects six investigative samples and continues to monitor chlorine residual and flush if necessary Health Advisory lifted
Collection Date: 9/29/2014 Results Reported: 9/30/2014 Total Coliform Absent Mercer Island Coliform Results
Mercer Island Timeline Tuesday - September 30 th Six investigative samples indicate no total coliform bacteria in the system Mercer Island collects six investigative samples and continues to monitor chlorine residual and flush if necessary
Collection Date: 9/30/2014 Results Reported: 10/1/2014 Total Coliform Absent Mercer Island Coliform Results
Mercer Island Timeline Wednesday - October 1 st Six investigative samples indicate no total coliform bacteria in the system Mercer Island collects six investigative samples and continues to monitor chlorine residual and flush if necessary
Collection Date: 10/1/2014 Results Reported: 10/2/2014 Total Coliform Absent Total Coliform Present and E. coli Present Mercer Island Coliform Results
Mercer Island Timeline Thursday - October 2 nd One of six investigative samples results indicate E. coli present in the distribution system Health Advisory re-issued Initial Action Plan is developed and implementation begins
Mercer Island Initial Action Plan Increase samples to 18 per day from throughout the island using standard collection protocols Dive the reservoirs Increase chlorine residual entering the tanks Inspect all construction sites Inspect all underground vaults Identify and test all high hazard backflow assemblies that had not been tested within the last 12 months Monitor chlorine and flush distribution system to displace the water
Mercer Island Timeline Sunday - October 5th Mercer Island child reported ill. Tests indicate sickness due to E. coli
Mercer Island Timeline Wednesday - October 8th The results of approximately 100 water samples collected since October 2 nd indicate no total coliform bacteria in the water system Action Plan implementation underway o Primary distribution grid flushed o Underground vaults inspected o Increased chlorine residuals in the distribution system o Backflow assemblies tested Health Advisory lifted
DOH Role Regulator Technical specialist Educator Risk communications Public health partner We want to be in the room with the decision- makers
Public Health – Seattle & King County Role Emergency response Permit food service establishments Technical specialist Educator Should be in the room with the decision-makers
Utility Partners City or County General Purpose Government Schools & School Districts Medical Community Business Community Adjacent Utilities Volunteers
Communications Distribute Notice within 24 Hours Message coordination News Release, Reverse 911, door hangers, social media, & webpage Scripts for news release, Reverse 911, webpage, & telephone Boundaries Staying ahead of social media
DOH Lessons Learned and Expectations A large chlorinated system – operational flexibility Incident Command Structure Response time Staffing requirements Communicating with Customers, Media & Partners Number and coverage of sample sites Best Management Practices The Revised Total Coliform Rule