WRF Webcast Case Studies to Identify Occurrence, Accuracy, and Causative Factors of Reverse Flow as Measured by Meters

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1 No part of this presentation may be copied, reproduced, or otherwise utilized without permission. WRF Webcast Case Studies to Identify Occurrence, Accuracy, and Causative Factors of Reverse Flow as Measured by Meters November 11, 2016

2 # Accuracy of In-Service Water Meters at Low and High Flow Rates

3 Case Studies to Identify Occurrence, Accuracy, and Causative Factors of Reverse Flow as Measured by Meters Project #4384 David Hughes, Orren Schneider, Minhua Xu American Water Steve Barfuss, Utah State University 3

4 Case Studies to Identify Occurrence, Accuracy, and Causative Factors of Reverse Flow as Measured by Meters Project #4384 David Hughes, Orren Schneider, Minhua Xu American Water Steve Barfuss, Utah State University

5 Case Studies to Identify Occurrence, Accuracy, and Causative Factors of Reverse Flow as Measured by Meters Project #4384 David Hughes, Orren Schneider, Minhua Xu American Water Steve Barfuss, Utah State University

6 6 Project Overview This second reverse flow project follows an initial research effort led by American Water Collect sample data from many more locations for a year s time to confirm statistics. Evaluate the accuracy and sensitivity of meters running in reverse. Demonstrate new tools used to evaluate case studies to investigate reverse flow events. Data logging Intelligent registers Geocoding Distribution system monitors 2

7 7 Project Approach Evaluate meter accuracy running in reverse Volumetric, Velocity and Static meters Verify frequency of reverse flow reports Identify causes Breaks, meter in reverse, hot water expansion, real backflow risks, customer tamper Test approaches to investigate to categorize causes and evaluate risk (find solutions) 3

8 8 Meter Reverse Flow Accuracy Meter Manufacturer and Types Tested Technology Displacement Piston Meters Nutating Disk Meters Single Jet Meters Multi-Jet Meters Manufacturer/Model Elster C700 Sensus SR Badger Recordall Mueller 400 series T-10 Metron Farnier Spectrum Jerman DLJ Master Meter Multi-jet Performance PME Non-mechanical Meters Badger E-meter (ultrasonic) Elster (fluidic oscillating meter) Sensus iperl (electromagnetic) 4

9 9 Meters Studied Included meters previously studied by Utah State Positive displacement and flow meters Tested newer static meters Electromagnetic meter (Sensus iperl) Ultrasonic meter (Badger e series) Fluidic Oscillating meter Previously tested by Utah State University but suspected register would not go backwards Tested meters as new and at 500,000 gallon flow intervals up to 2,000,000 gallons 5

10 10 Meter Testing Data Utah State University Had performed tests on meters previously Identified issues with forward flow (WRF #4028) 6

11 11 New Meters - Forward Flow Most meters performed well Low flow standard (5/8) is 95% at ¼ gpm % 95.00% 85.00% 75.00% 65.00% 55.00% 45.00% 35.00% 25.00% 15.00% 5.00% ultrasonic meter nutating disk meter displacement piston multijet multijet nutating disk meter nutating disk meter displacement piston displacement piston electromagnetic meter single jet fluidic oscillating 7

12 12 New Meters Reverse Flow 160% *Reverse Flow Data for 5/8X3/4-inch meters at 0 life Registry 140% 120% 100% 80% 60% 40% 20% 0% -20% -40% -60% -80% -100% -120% ultrasonic meter nutating disk meter displacement piston multijet multijet nutating disk meter nutating disk meter displacement piston displacement piston electromagnetic meter single jet fluidic oscillating -140% 1/16gpm 1/8gpm 1/4gpm 1/2gpm 1gpm 2gpm 15gpm 20gpm 8

13 13 New Meters Reverse Flow Positive displacement and electromagnetic meters perform the best over full range of flows Piston meters and multijets not as accurate Ultrasonic meters have problems at high flow. Fluidic oscillating meter failed to run in reverse 9

14 14 Testing meters after heavy use 10

15 15 Testing meters after heavy use Positive displacement and electromagnetic meters continue performing the best over full range of flows Jet meters and ultrasonic at high flow still have issues Some degradation of performance except for static meters 11

16 16 Intelligent Meters Neptune has intelligent meters called ecoders available as free standing meter or integrated with an AMR transmitter Intelligent meters monitor flow every 15 minutes and will flag backflow if read is less than previous read. Minor backflow if detectable gallons Major backflow if 10 gallons or more Datalogs past 96 days of hourly reads Employed in first study, limited MDM 12

17 17 Reverse Flow Data Issue One dilemma is overlapping alarms. Alarms active in system for 35 days but read intervals shorter 1 backflow = 2 alarms? The more frequent the alarms at a location, the less probable that the overlap is sustained 3 consecutive months of backflow means at least 2 alarms. 13

18 18 Intelligent Transmitters AW changed to Mueller meters and AMR in Mueller and other manufacturers placing intelligence in the AMR transmitters Transmitters compare reads every hour Backflow flag sent if reverse flow 10 gallons or more that registers for 6 hours or more in last 30 days. Transmitters datalog hourly reads for 170 days American Water made commitment to a meter data management system to capture a variety of alarms including backflow 14

19 19 Altered Data Management System In 2012 Smart Earth Technology (SET) hired to manage AW water meter readings to enable same time readings from multiple AMR systems (Mueller and Neptune) SET meter reading system on line October 2012 AW initially lost access to reverse flow codes. Fathom acquired SET and proceeded to restore full data reporting, partial but not historical in September 2012, full access in early

20 20 Multiple System AMR Reads 16

21 Reverse Flow Data System acquires alarm errors from reads from AMR vehicle collectors, not errors from handheld units, a major percentage of reads. System not separating types of backflow (major and minor) 17

22 22 Evaluating Data Available reverse flow data collected and grouped by state September 2012-August Information from database sorted and organized by district by state by month. Sufficient data from vehicle collectors to identify significant reverse flow frequency though not quantified and investigate candidates. (Likely to be minor backflow). Meters read by vehicle increased in the process. 18

23 23 Analyzing Data Monthly September 2012 to August 2013 data from vehicle sources totaled 13,866 reverse flow events from seven states. 6,646 locations had a single reverse flow event 7,220 other events came from 2,321 locations having multiple reverse flow events. Statistically 272 events of the multiple events would have been double recorded. # of reverse flow Events PA VA IA NJ IL IN CA 19

24 24 What was the sample size? really good question In 2014 study period, AW had over 600,000 intelligent meters capable of reporting reverse flow and increasing number of transmitters - over 100,000. But AW lacked a breakdown between vehicle and handheld collection but the guess at the time and this was also estimated. The first study of a 1% estimate of backflow alarms in reads appears correct. 20

25 25 Alarm analysis one location, multiple alarms Checking number of events in 12-month period 1 alarm per address means isolated case, not chronic problem 2 consecutive monthly alarms per address may a repeat alarm 3 consecutive monthly alarms per address may mean two or three events (one may be repeated) 12 alarms per address may mean 6-12 events (possibly repeated but thought less likely if seen all the time) Multiple alarms will be easier to investigate if reverse flow pattern repetitive, established. Highest priority will be repeating neighborhood events that suggest operational issues. 21

26 26 Alarm Analysis One Location, Multiple Alarms Why is this single location providing monthly alarm and there are no other alarms in the area? 12 alarms means isolated case, but chronic problem. Suspected cause: customer plumbing, tamper can be checked out by looking at datalogged hourly reads. 22

27 27 Alarm Analysis One Location, Multiple Alarms What are possible causes: customer action? date of read reading address 10/4/ Discovery Court 11/5/ Discovery Court 12/5/ Discovery Court 1/4/ Discovery Court 2/5/ Discovery Court 3/7/ Discovery Court 23

28 28 Datalogging Analysis Six locations with reverse flow history in Greenwood Indiana were investigated 96 days of backflow data were provided in early Location #4 was a warehouse,; the others were residential Four had backflows as shown. 24

29 29 Datalogging Analysis It was noted that many of the alarms happened at the end of the day and were modest hourly volumes. It was noted previously that the number of backflows were highest in winter months. Hot water expansion was suspected as a prime cause. 25

30 30 Diving into Datalogging Thermal Expansion A 40-gallon hot water heater starting with water at 39 degrees (expands if it is colder) that heats up to 136 degrees equates to 0.45 gallon expansion for the 40 gallons. How long would it take to heat the water? If it takes 5 minutes that is a flow rate of.09 gallon per minute. In five minutes that expansion would be.45 gallons more than four times the volume needed to trigger an alarm (allowing for inaccuracy at such a low flow. Larger tanks or turnover increases backflow. 26

31 31 Diving into Datalogging Using the Tools Researchers also used a device that convert AMR to AMI using cellular technology and this also capture low level backflows. Results showed minimal backflows During early 2015 effort, no major backflows found 27

32 32 Alarm Analysis Multiple Locations, One Month Look at 12 months of geocoded data and check number of events 1-2 alarms occurring at multiple close proximity locations suggests a distribution system issue 3 or more alarms means a distribution related event that may be chronic Check with distribution operators to identify likely cause. Main break severe enough to drain customer plumbing or sudden pressure changes 28

33 33 Alarm Analysis Multiple Locations, One Month Why are so many locations reporting a single alarm in one area in November 2012? 1 alarm month means isolated event, but broader distribution issue may be the cause. Possible cause: main break, hydrant flushing, fire event, distribution maintenance operation. 29

34 34 AMI Backflow Alarms Update Several severe main breaks in a PRV fed system created multiple alarms 1-2 alarms occurring at multiple close proximity locations suggests a distribution system issue 3 or more alarms means a distribution related event that may be chronic Check with distribution operators to identify likely cause. Main break severe enough to drain customer plumbing or sudden pressure changes 30

35 35 Learning from Detailed Reverse Flow Data - AMI Access AMI connected system had 66 units during earlier study, now has 300. Originally units placed strategically, new units placed more randomly. Units connected to AMI system. Alarms are time stamped with reading and sent as they happen. Main breaks a major cause of groups of failures but need to investigate other individual issues. 31

36 36 Detailed Reverse Flow Data - AMI Access date time condition address 05/11/12 11:30:21 Reverse Flow Between Minimum and Maximum 132 Brk Ave. 05/11/12 11:45:01 Reverse Flow > Maximum 132 Brk Ave. 05/11/12 12:00:48 Reverse Flow Between Minimum and Maximum 246 Ws Rd. 05/11/12 12:03:44 Reverse Flow Between Minimum and Maximum 231 Qu St 05/12/12 12:41:20 Reverse Flow Between Minimum and Maximum 221 S. Pct St. 05/12/12 12:43:56 Reverse Flow > Maximum 222 S. Pct St. 07/02/12 7:40:04 Reverse Flow > Maximum 132 Brk Ave. 07/27/12 2:18:00 Reverse Flow Between Minimum and Maximum 536 1/2 E.Cra Ave. 08/15/12 8:50:50 Reverse Flow Between Minimum and Maximum 205 E. Fa St. 08/25/12 3:46:57 Reverse Flow Between Minimum and Maximum 1524 Ha St. 32

37 AMI reverse flow monitoring Interconnected alarms to AMI capture events May 11, 2012 event showed 6 backflow monitors running backwards up to 869 gallons. July 2, 2012 event showed 6 backflow monitors running backwards up to 150 gallons. Backflows in this system usually suggest a main break at a low elevation and loss of pressure at higher elevations enough to reverse flow in meter and send air into system as pipe drains. May backflow monitors July 2 event event Backflow (typ) Main break Backflow (typ) 33

38 38 Customer usage profile from AMI Backflow events created reverse flow alarm readings in addition to normal AMI reads taken 6 hours apart The larger backflow was likely air entering the system through an open customer fixture and represents a water quality risk and a credit for the customer in metering. The meter reading drop on July 2 did not fully recover until the evening of July 3, suggesting loss was not all water. 34

39 39 Alarm Analysis Multiple Neighbor Locations, One Month Confirm through geocoding or street names and common month. date reading address 10/10/ Brentwood Rd 10/10/ Brentwood Rd 10/10/ Heller Dr 10/10/ Brentwood Rd 10/10/ Brentwood Rd 10/10/ Fairfield Rd 10/10/ Austin Drive 35

40 40 Major Alarm Analysis Multiple Locations, Multiple Months Why are so many locations reporting multiple alarms in one area in 6 months? 1 alarm month means isolated event, but broader distribution issue Suspected cause: pump, operation, repeated main breaks, water quality hydrant flushing, fire hydrant use, distribution maintenance operations. 36

41 41 Backflow Update 2015 Neptune integrated meters (first installed in 2005) number about 700,000 units across American Water Can distinguish between minor backflow (< 10 gallons) and major backflow and holds record for 35 days after event All AMR intelligent meter alarms were transmitted including those from handheld AMR collectors. With change in MDM in early 2015, we cannot track history prior to implementation. Mueller Hot Rod transmitters number about 600,000 units and track backflow 10 gallons or more that last for 6 hour intervals 37

42 42 Backflow Monitor Issue Initial study in Spring 2015 of major backflows showed high number of repeating locations. Local staff datalogged 12 locations in St. Josephs, MO that had a high number of repeating major backflow scattered throughout the system. Analysis revealed a glitch in the Neptune software. Some units made in early 2011 could send out false positive major backflow. 38

43 43 Backflow Monitor Issue Manufacturer acknowledged and found problem Manufacturer sent list of 13,600 units a problem Research team identified some units Neptune missed (about 400), which delayed the analysis 39

44 44 Backflow Strategy Revisited Looked at ratio of major backflow events to number of 2015 detection opportunities (span is 8-12 possible reads) Look in detail at events in systems where ratios are highest Primary sort in spreadsheet by meter routes Then sort by AMR identifier or by date Data separates the various categories of major backflow Isolated events one location once per year Isolated event involving cluster of customers in an area Multiple events one location, two nonconsecutive or more events Multiple events, multiple locations 40

45 Backflow Analysis Frequency of major backflows is 0.13% of reads (about 1 of every 750 reads) 41

46 46 Backflow Investigation Example Warrensburg, MO main breaks 42

47 47 Backflow Investigation Example Brunswick, MO faulty backflow preventer preventer 43

48 48 Converting Backflow Data to GIS NJ American responded to an unresolved issue of detecting meters installed in reverse by placing backflow data on GIS 44

49 49 Summary of Backflow Findings Backflow occurs in volumes large and small Minor events appear to be hot water expansion Major events should be examined if repeating frequently at a single location occurring in clusters at the same time And especially if repeating in clusters Backflow alarms vary by manufacturer, they may be becoming programmable not much value in monitoring flows less than 1 gallon 45

50 50 Summary of Backflow Approach Recommend year of data to identify trends Graphic interface can help Pursue low hanging fruit Focus on repeat events likely to recur Consult with operations to explain events impacting multiple locations at same time For unexplained multiple events or multiple locations deploy dataloggers, mobile AMI meters Investigation aided by meter logging, portable flow and pressure monitors in your toolbox 46

51 Contact Information Dave Hughes, American Water Phone (856)

52 Q&A Session 48

53 Thank You Comments or questions, please contact: For more information visit: