1. Coliform Event Recommendations and Best Management Practices Sammamish Plateau Water and Sewer District Workshop December 9th, 2014 Sammamish Plateau Water and Sewer District Workshop December 9th, 2014 Melinda Friedman, P.E. Confluence Engineering Group, LLC www.confluence-engineering.com

2. Presentation Overview City of Mercer Island After Action Assessment  Objectives and Approach  Coliform Occurrences Pathways  Key Findings Preliminary Recommendations and Summary of Best Management Practices 2

3. Recommendations in Three Key Areas Reduce Contamination Risks Enhance Water Quality Management Additional Improvements  Resource Availability  Written Documentation  Data Management 3

4. Reduce Contamination Risks Inactivate and Purge System of Initial Contamination Slug  Increased chlorine residual  Conducted flushing to replace water in system Minimize Risk of Future Contamination  Eliminate pathways  Retrofit air-vac vaults  Update and enhance cross connection control ordinance, surveys, and enforcement  Demonstrate pressure maintenance  Install high-speed portable pressure dataloggers  Maintain elevated chlorine residuals  On-going chlorine boosting and mixing  Reducing water age  Reducing pipe wall demands 4

5. Boosted chlorine residual results 5 SPU Inlet Target Range

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8. Need for Enhanced Main Cleaning Reduce disinfectant demand Reduce shielding of microorganisms Improve flow, pressure, water quality Flushing program constrained by discharge limitations Additional study needed:  Demonstrate effectiveness (or lack of) current flushing program for main cleaning  Desk top and field evaluations alternative main cleaning strategies  Ice pigging  NO-DES (no discharge flushing system)  Swabbing of cement lined and AC pipes  Pigging and relining  Develop metrics and use data collected to help prioritize main replacements Optimize use of staff and water resources while improving water quality delivered to customers 8

9. Enhancing Water Quality Management Develop and implement a water quality surveillance monitoring program  Understand water quality conditions  From POE to meter  Spatially and seasonally  Identify potential upsets  Timely data for quick decision making 9

10. Written Documentation City does not have documented Standard Operating Procedures for preventative and response O&M activities  Needed to retain institutional knowledge within and across departments  Needed to ensure consistent application of best practices Develop and document in several areas:  Inspection and maintenance of vaults and valves  Bypass valve operation  Storage facility inspection, operation, and maintenance  Booster disinfection  Analytical equipment calibration and upkeep  Surveillance water quality monitoring  Other 10

11. Data Management Current field data collection/retention is paper- based  Time consuming for IT to convert to actionable electronic information  Slowed City’s ability to map and visualize information in response to event Field data collection practices not always consistent impacting data quality Electronic record keeping and real-time asset management very common in industry Increase ability to track, trend, and understand asset location, condition, water quality, etc. 11

12. Resource Availability Prior to event, staff were stretched too thin to keep up with the high demands of managing an aging distribution system Initial incident response has gone well  Due to highly capable, diligent staff  Significant external support Additional resources clearly needed  Conduct needed evaluations  Implement recommendations  Ensure City meets industry best management practices  Enable rapid response to potential future event  Improve quality and consistency of water delivered to customers 12

13. Conclusions – MI Event City is fortunate to have knowledgeable, diligent, capable staff Scrutiny of practices and system conditions uncovered opportunities for improvement, as would be the case for most water systems regionally and nationally The City has meaningful opportunities to:  Reduce contamination risk,  Enhance water quality and asset management, and  Optimize practices and resource use Additional resources will be needed to implement recommendations 13

14. WaterRF 4109 and AWWA Partnership for Safe Water – Distribution Systems 14

15. Optimization Criteria 15 Chlorine Residual Water Quality Integrity PressureHydraulic Integrity Main Breaks and Leaks Infrastructure Integrity

16. Self-Assessment Against BMPs to Meet Optimization Criteria Customer Complaint Cross Connection Control Disinfection Residual Disinfection Byproducts Disinfection of New Mains or Repairs Distribution System Flushing Energy Management External Corrosion Control Hydrants, Blowoffs, Valves Hydraulic, Pressure, Water Age Inorganics Accumulation and Release Internal Corrosion Main Breaks and Leaks Nitrification Control Post Precipitation Samples, Micro, Biofilms Security and Emergency Storage Facility Maintenance Water Leakage Water Quality Integrity Hydraulic Integrity Infrastructure Integrity 16

17. Coliforms Happen! Proactively assess your practices and risks  Source water contamination pathway  Distribution system pathways  Sample collection/analytical pathways Incorporate water quality protection into your CIP Review your TCR Plan – does it do what you need it to do? Enhance communications between purveyors and wholesalers 17 There are ALWAYS opportunities to reduce risk, preserve public trust, and improve public health protection!

18. Questions/Discussion 18