1 EBMUD Flow Monitoring Technologies Evaluation Study Presentation BACWA Collection Systems Committee Meeting February 25, 2009 Kevin Krajewski, P.E. V&A

2 Acknowledgements Sponsoring Agency - Technical Assistance and Field Work - Represented Companies

3 Project Overview Flow Monitoring Technologies Evaluation Study 31 Sites Monitored for Flow Monitoring and I/I Study –Pipe Sizes ranged from 8-inch diameter to 105-inch diameter –Varying types of hydraulic conditions 5 Types of Open-Channel Flow Monitoring Technologies 10 Flow Meter Models made by 6 Manufacturers

4 Site Locations 10 test site locations to allow for direct comparison of flow data Site 27 EBMUD District MH S45 84-inch RCP 6 different flow meters installed and evaluated

5 Area-Velocity Flow Metering – Q = V x A, where Q = flow V = average velocity A = wetted cross sectional area Primary Devices (Weirs and Flumes) – Devices that alter flow in a predictable manner so that a known relationship between flow and measured depth can be utilized Requirements for Measuring Flows

6 Types of Metering Technologies Evaluated TechnologyManufacturerFlow Meter Model # of Meters installed Continuous Wave Doppler Teledyne Isco Hach ADS 2150 Sigma 910 FlowShark Pulse Doppler Teledyne Isco ADS ADFM AccQMin FlowShark Pulse Radar Hach Marsh-McBirney Flo-Dar6 Transit-Time ADS Accusonic1 Custom Compound Weir SFE Global 2 Transit-Time with Flume Accuron FlowScope1

7 Hach Sigma 920 Continuous – Wave Doppler Teledyne Isco ADS Flow Shark $6,000 - $7,000$5,500 - $6,500$6,500 - $7,500 O&M requirements – planned periodic (every 2 – 4 weeks) Typical for temporary efforts.

8 Pulse – Wave Doppler Teledyne Isco ADFMTeledyne Isco AccQMinADS Flow Shark Pulse $17,000 - $19,000 $10,000 - $12,000 $10,000 - $14,000 O&M requirements – planned periodic (every 2 – 4 weeks)

9 Radar Hach Marsh-McBirney Flo-Dar $10,000 - $12,000 O&M requirements -- responsive to questionable data and surcharge events

10 Transit-Time Accusonic Accuron FlowScope >$20,000 $5,500 - $6,500 O&M requirements – planned periodic (every 2 – 4 weeks)

11 Custom Compound Weir (CCW) SFE Global O&M requirements – planned periodic (every 2 – 4 weeks) $16,000 - $17,000 Installed

12 Flow Level and Submerged Pressure Transducers Submerged pressure transducer: measures the hydrostatic pressure of the liquid above the transducer (proportional to liquid level) – Subject to fouling or “drift” Ultrasonic level meters transmit a pulse to the surface of the liquid and measure the time it takes for the pulse to be reflected back to the meter. – Down-looking (non-submerged) or Up-looking (submerged)

13 Site 27 Level Data Level Data

14 Accuracy and repeatability Uptime Installation/removal maneuverability O&M maintenance User-Friendliness (hardware & software) Compatibility (to Remote monitoring options) Connectivity Cost Evaluation Criteria

15 Analysis: Site 27

16 Sigma 910 ADFM Flo-Dar Flow Shark Pulse

17 A Marsh-McBirney Flo-Mate Portable Velocity Meter was used for velocity profiling. Multiple point velocity readings were measured throughout the flow stream to create an accurate velocity profile so as to determine average velocity. This is necessary with the Marsh- McBirney Flo-Dar. Velocity profiling was conducted multiple times at various times of the day (high flow, low flow, etc.) Flow Velocity Profiling

18 Analysis: Site 27 * velocity taken from period 3/20/2008 to 4/26/2008 Meter Type Average Velocity* (fps) Hach Sigma 910: 2.87 Teledyne Isco 2150: 2.61 Teledyne ADFM: 3.05 ADS FlowShark Pulse: 2.61 Hach Marsh-McBirney Flo-Dar: 2.95 Accusonic: 2.63 Average Velocity per Velocity Profiling: 2.91 Minimum/Maximum % Difference: ±8%

19 Regardless of manufacturer’s specifications, it cannot be assumed that velocity measurements for any meter will be accurate within ±2%. Velocity profiling should be conducted with any meter selected for use in a large diameter pipe. Continuous-Wave Doppler flow meters are not appropriate for long term installations in large (39” or greater) diameter pipes with flow depths of the magnitude measured in Site 27. Conclusions for Site 27

20 Continuous – Wave Doppler Limitations Low Flow (~14-18”) Sensor penetrates most of flow, most accurate velocity Medium Flow (~24-36”) Sensor less than half of flow, does not pick up peak velocity. High Flow (36”+) Sensor minimal portion of flow, velocity not representative of actual flow Velocity Sensor Range (~16”) Velocity Sensor – offset at 5:30

21 Meter Summary: % Usable in Study Locations 74% 3% 45% 58% 87% 16% 10% 16%

22 Meter Summary: Continuous Wave -Best used in 8-inch to 42-inch pipe (generally – depends on site conditions) -Good flexibility in most situations -Good for surcharged conditions -Cost effective option -Isco and Sigma: more user friendly, slightly less expensive -ADS Flow Shark slightly better data, expect connectivity issues -Required periodic maintenance

23 Meter Summary: Pulse-Doppler -Best used in larger diameter pipe meeting minimum flow conditions. -More expensive (generally) -ADFM and AccQMin: Slightly better data, but expect issues in pipe with sediment. More expensive than ADS. -ADS Pulse: Can handle sediment, less expensive, user friendly -Required periodic maintenance

24 Meter Summary: Radar -Can be used on nearly all sized pipelines -Good flexibility for most situations -Sometimes only option, especially high velocity, small pipe diameter sites, or dangerous confined space entry situations -Questionable for surcharged conditions -More expensive -Expect connectivity issues for DC powered sites (AC power okay) -Requires responsive maintenance (surcharge events)

25 Meter Summary: Transit-Time Accusonics -Best used in larger diameter pipe -Requires commitment for metering site (difficult to remove) -Accurate Velocity Data -Required periodic maintenance: Most O&M to clean sensors

26 Meter Summary: Transit-Time Flow-Scope -Only for smaller diameter pipe with tight tolerances. -(will be) Cost-Effective -Emerging technology. Not ready just yet. -Best for 8 to 12 inch pipe with low velocity, low level flows. -Required periodic maintenance

27 Meter Summary: Custom Compound Weir -Best for specific applications: high turbulence, convergence of two lines, or extremely low flows -Expensive -Dedicated permanent site, each site custom built. -Required periodic maintenance

28 Results Summary [1] Pipe Size Definition: Small = 15” and below, Medium = 18” to 36”, Large = 39” and above. [2] This category was defined by the number of flow monitoring sites within the EBMUD project (31 sites total, pipe diameters ranging from 8 inches to 105 inches, and all types of hydraulic conditions) wherein the given type of meter could have been appropriately used for obtaining good flow monitoring results. Most = >80%, Several = 60% - 80%, Many = 40% to 60%, Unique = <40%. Note – these results will vary depending on the characteristics of the collection system being evaluated. [3] $ = $5,000 - $9,000, $$ = $9,000 - $14,000, $$$ = $14,000 - $19,000, $$$$ = greater than $19,000.

29 General Decision Tree, Pulse Pulse, Pulse Pulse

30 Decision Tree (cont.) Output from Depth/Velocity Matrix Sediment > 2 inches? ADFM and AccQMin Meters must be mounted at the pipe invert and may not be appropriate. Permanent vs. Temporary Installation: Meter Maintenance Submerged sensor meters (all meters except the Flo-Dar) are prone to fouling and may require a confined space entry for sensor maintenance. Required Accuracy vs. Cost What are the overall requirements for accuracy? Are the flow results to be used for billing purposes (high accuracy required)? To monitor for potential surcharge situations (high accuracy not required)? Pipelines known to have repeated surcharging? Submerged sensor meters perform better in surcharge situations than Radar, Weir and Flume meters

31 Q & A