Coliform Event Recommendations and Best

Management Practices

Sammamish Plateau Water and Sewer District Workshop

December 9th, 2014

Melinda Friedman, P.E.Confluence Engineering Group, LLC

www.confluence-engineering.com

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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

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Recommendations in Three Key Areas

Reduce Contamination Risks Enhance Water Quality Management Additional Improvements

Resource Availability Written Documentation Data Management

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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

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Boosted chlorine residual results

SPU Inlet Target Range

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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

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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

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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

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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.

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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

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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

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WaterRF 4109 and AWWA Partnership for Safe Water – Distribution Systems

Optimization Criteria

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Chlorine Residual

Water Quality Integrity

Pressure Hydraulic Integrity

Main Breaks and Leaks

Infrastructure Integrity

Self-Assessment Against BMPs to Meet Optimization Criteria

Customer ComplaintCross Connection ControlDisinfection ResidualDisinfection ByproductsDisinfection of New Mains or RepairsDistribution System FlushingEnergy ManagementExternal Corrosion ControlHydrants, Blowoffs, ValvesHydraulic, Pressure, Water AgeInorganics Accumulation and ReleaseInternal CorrosionMain Breaks and LeaksNitrification ControlPost PrecipitationSamples, Micro, BiofilmsSecurity and EmergencyStorage Facility MaintenanceWater Leakage

Water Quality IntegrityHydraulic IntegrityInfrastructure Integrity

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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

There are ALWAYS opportunities to reduce risk, preserve public trust, and improve public health

protection!

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Questions/Discussion