Louisville s Water Works

Transcription

1 Maintaining Louisville Water s Louisville s Water Works Best Tasting Tap Water Celebrating Vince Monks 150 Years Rengao Song, Ph.D. of Service Eric Zhu, Ph.D. Chris Bobay Water System Optimization Conference October 29, 2015

2 Presentation Outline Background & Challenges LWC s optimized disinfectant residual management approach Take-home Message Q/A

3 Best Water Must Meet 3 Standards Meet/exceed stringent and complex regulations: health risk issues or safe to drink Pathogens Organics (spills & pesticide contamination) Inorganics (lead and copper) Distribution water quality and residual management 90+ contaminants required for simultaneous compliance Maintain/improve customer satisfaction: aesthetics issues or best tasting Taste & Odor (algae, di-chloramine) Discolored water (red water, black water) Customers often use aesthetic parameters as water safety indicators Maintain public understanding and trust: perceived risks Detection of unregulated chemicals: Dose makes the poison! NGO, media, societal and political pressures: Upgrade treatment goals Customer response to the EWG report on Cr-6 exceeded the response to the annual rate increase

4 1T2G3A 1T = 1 Team with 5Cs of character, comprehensiveness, communication, commitment, and creativity 2G = 2 Goals (WIG/Bread & PIG/Ice-cream) 3A = 3 Approaches (Optimization-empowerment, Emergency-management, Data-driven process)

5 1 Team with 2 Goals WQ Compliance & Process Control Assure WQ compliance (federal, state, & local) Monitor WQ for treatment & distribution operations Provide WQ analysis for internal & external customers WQ and Treatment Research Provide guidance & technical support to Operations Provide Process Engineering (RBF, Blending Studies, etc.) Research (Cr-6, Ozone, RBF, ) Distribution WQ Management Maintain disinfectant residual throughout DS Address/minimize WQ customer complaints Manage cross-connection control

6 Distribution System Optimization Program LWC Achievements Phase I Charter member (2010) Phase II Annual data collection ( ) Phase III Directors and Excellence Award for focus on self-assessment and improvement planning (2013) Phase IV Implementation of identified optimization strategies (IN PROCESS) 6

7 LWC DS 625 sq. miles & 3 county retail service area 309,000 services/>850,000 customers >4,200 miles of pipeline >30 tanks: 100,000 to 30MG 40 booster stations 24,000 fire hydrants and 52,000 valves 30 different pressure zones

8 LWC Disinfectant Residual Management Challenges Decreasing Consumption Expanding Infrastructure Nitrification

9 LWC Residential Consumption ( ) 9

10 Factors for Declining Consumption Weather impacts Transition from manufacturing to service economy Federal regulation on low flow appliances Increasing rates (water and wastewater) Economic impacts (recession periods) Improvements in water productivity and water mgmt Conservation awareness and practice

11 LWC DS Growth Rationales Building a primary and secondary transmission grid/storage for fire flow in accordance with the National Fire Protection Association (NFPA) standards Creation of a modified urban system in the 1990 s to extend main to very low density areas Future demand planning assumptions Expansion of the core infrastructure to receive new and/or potential customers, including future regional supply solutions. 11

12 Nitrification in DS Water age Temperature Free NH3 Cl2 residual 12

13 Comprehensive Evaluation of LWC s Disinfectant Residual Challenges Water Age Analysis Chloramine Decay Profiling Daily Demand/Main Mileage Relationship Innovative Approach Hydraulic/Water Quality Modeling 13

14 29 miles LWC Aveg Water Age 45 miles Analysis performed using InfoWater MSX Software (Innovyze, Inc.) 14

15 Zone 1 & 2 Characteristics Customer Base Light commercial Low density single family residential development Agricultural/rural water use Hydraulics Over-sized infrastructure for fire flows & future build-out Long Hydraulic Retention Time Water Quality High water age T&O customer complaints Nitrification in DS and tank Lower average chlorine residual 15

16 Chloramine Decay Profiling Establish decay baseline for LWC waters Assist in nitrification risk assessment Support model development Guide future DS treatment design CHFP BEP 1:1 Blended CHFP BEP 1:1 Blended Total Chlorine, mg/l Free NH3-N, mg/l Days Days

17 Louisville vs. A Mid-West Utility # Customers Aveg. Daily Demand (DD) Main Miles (MM) System DD (MG) MM (100 s) DD/MM Ratio Louisville A Mid-West Utility

18 DD/MM Ratio vs. DWQ Mgmt Effort 18

19 LWC WQ Modeling Water Age Model: Full-system/all-pipe model A snap-shot hydraulic calibration (summer/winter) based on operational data and field collected data Water age modeling strongly correlates to DS samples Model Enhancement Needs Improved hydraulic base model (ongoing maintenance) Multi-species modeling (chloramine,... ) Real-Time/predictive modeling 19

20 Optimized Approaches in Disinfectant Residual Management & Maintenance Treatment Optimization DS WQ Surveillance & Monitoring Storage Tank Management/Flushing Cross-connection Control Coordination with Capital Project DS Treatment & Nitrification Control 20

21 Residual Management Water Treatment Plant Minimize chloramines decay potential Maintain ph >8.5 Ferric/Poly-DADMAC co-coagulation strategy ph adjustment Chlorine/ammonia ratio (3.25:1, <55 F) Minimize nitrification potential When >65 F, minimize free ammonia (<0.1mg/L) by maintaining chlorine/ammonia ratio of 3.5:1 Plant on-line monitoring (free ammonia, total ammonia, monochloramine, and total chlorine) 21

22 Plant On-line Monitoring 22

23 DS WQ Surveillance and Monitoring It s a Numbers Game! Maintain Stringent Disinfectant Residual Guidelines ~4D ~1.5D Tank Total Chlorine (mg/l) 1.5 mg/l 0.5 mg/l - Regulation Time 23

24 DS WQ Surveillance and Monitoring Storage Facility Monitoring Grab sample - Analyzed for key signs of nitrification Online Instrumentation (total chlorine) Master Meters to Consecutive Systems Sampling 2x/month: >55 F, 1x/month: <55 F Building in Online Instrumentation (total chlorine) WQ Customer Complaint Monitoring System-wide complaints: Treatment related Area-wide complaints: Treatment, DS, both or single event related Individual complaints: Premise plumbing issues/ds issues - deadends/closed valves 24

25 DS WQ Surveillance and Monitoring Online vs. Grab Sample (denoted by *) Floating Tank in LWC DS Total Chlorine Residual (mg/l) 2.7 mg/l * * 2.0 mg/l 2.4 mg/l * ~2.0 mg/l Swing WQ in Tank Appears Acceptable by Grab Sample Results Assure timing of grab sample or install online WQ instrumentation. 25

26 Data-driven Flushing Multiple Flushing Approach Preemptive flushing Reactive flushing Customer complaint flushing Active routine flushing Dead-end flushing/master meter Boundary valve by-pass Multiple Flushing Techniques Permanent auto-flushing (long term) Portable auto-flushing (short term) Blow-offs Flushing crews (manual) Spot flushing Localized flushing Unidirectional flushing 26

27 Storage Facility Management Temporarily Reduce Storage Volume Take redundant floating tanks out of service when possible Change operating range of tank Pumping Strategies Mandatory >30% daily turnover (temp > 55 F) on tanks operated by BPS (goal: 100% turnover ~3 days). Increase flow into pressure zone by turning on all pumps during fill cycle (Increases velocity in tank for stratification issues/decreases overall cycle time) Mixing LWC selectively employs passive and active systems Should be tank specific may not be one size fits all Determine when mixing system, if any, will help 27

28 Cleaning & Inspection Removes sediment/biofilms Identifies sanitary/structural deficiencies Industry/AWWA = every 3-5 yrs; BMP = annually LWC employs a weighted scoring decision tool for frequency Steel Tank (Chemical) During Concrete Tank (Washout) Before After After 28

29 LWC CCP Joint Effort Among LWC, Customers and Contractors LWC Owns CCP Administration (by federal EPA) Staffed Program Manage customer database Manage annual contractor testing including notifications Enforcement (LWC SR&Rs, Metro Ordinance, DOP) QA/QC (LWC inspections and contractor testing) Educate public/partnership with regulatory agencies Self-sustained Program (administration fee charged) LWC CCP Administration LWC QC (Office/Field) Risk assessment through inspections Customers/Contractors BFPD installation & annual testing 29

30 Risk is Spatially Located 30

31 Work on the Front-end (Capital) Influence Capital Projects from WQ View Develop internal WQ review process Refine Infrastructure Design Criteria Level of service evaluation: pressure/flow (urban vs. rural) Design alternative fire flow infrastructure Phased-in design solutions: PRV => VFD => Tank Assure Proper Storage Tank Design Influence location, size, type, etc. Assure proper mixing (Evaluate inlet nozzle changes vs. active mixing systems to assure effectiveness) Reduce Dead-ends: Looping/Grid-tie Projects 31

32 Chlorite Nitrification Inhibitor in DS (Zone 1) Low level dosage of ~0.4 mg/l is effective for control Early application prior to nitrification development is needed Less effective where nitrification is already proliferating Total Chlorine Nitrite Total Chlorine Residual, mg/l Started Chlorite Application Stopped Chlorite Application Nitrite, mg/l Time 32

33 2007 and 2012 Comparisons Area DD/MM Ratio Avg. Total Cl (mg/l) DD/MM Ratio Avg. Total Cl (mg/l) LWC LWC Bullitt County Zone Zone Zone 1: Chlorite ( ), 56% => 81% of LWC Avg. Zone 2: No Chlorite ( ), 44% => 54% of LWC Avg. 33

34 Take-home Message Understand your distribution system in order to find right solutions for disinfectant residual management like DD/MM may be a good utility specific indicator of potential issues Yesterday s disinfectant residual management strategies are not adequate for today s challenges Development of a holistic/multi-pronged & utilization of new technologies/strategies are necessary to address this issue 34

35 Questions/Answers Vince Monks