Reality Flow Monitoring: Lessons Learned Pipes Half Full or Half Empty? MWEA Collection Systems Seminar October 2, 200 Steve Kalinowski, PE Flow Monitoring Realities Metering is not an exact science Metering is not an exact science Collection systems are harsh environments for equipment Difficult working conditions for installing, calibrating, and maintaining meters (confined space entry) 1
Flow Meter Technology Old School New School Tip #1: Take Care of Your Field Crews Provide proper equipment Provide proper equipment Provide necessary training Listen carefully to what they say Give feedback (both positive and negative) 2
How Many Meters and for How Long? Owner perspective Regulatory perspective Technical perspective Theories on Approach Use more meters to isolate problem areas Use more meters to isolate problem areas Use longer period to capture more events and seasonal fluctuations Move meters around to cover more areas within monitoring period 3
Reality Most monitoring programs are in response to regulatory compliance issues Both time and budget are limited Limited data sets result requiring more conservative projections and extrapolations More Reality If you want dry weather: If you want dry weather: - Start flow metering or extend your monitoring program If you want rain: - Pull your meters or postpone your monitoring program 4
Tip #2: Selecting Monitoring Sites and Duration Consider combination of long- and short-term monitors Start by using an end-of-system meter to develop understanding of system flows Balance upfront cost for monitoring program with potential capital cost savings for future improvements Tip #3: Example Lessons Learned (Things to Watch Out For) Differential flow monitoring Level sensors Rain gages Using data from other sources System operations Data collection/quality review 5
Differential Metering Necessary to isolate flow segments and reduce number of meters Flows should balance (DS>US) for volumes Not very effective for incremental peak flows due to attenuation Sometimes doesn t work for peaks or volumes usually points to a meter problem Errors compounded with number of meters used Ideal Upstream to Downstream Differential Metering 3 Meter1 Meter2 Meter3 EOS Meter Meter1+Meter2+Meter3 2 Flow (cfs) 1 0 4/26 0:00 4/26 3:00 4/26 6:00 4/26 9:00 4/26 12:00 4/26 15:00 4/26 1:00 4/26 21:00 4/27 0:00 4/27 3:00 4/27 6:00 4/27 9:00 4/27 12:00 4/27 15:00 4/27 1:00 4/27 21:00 4/2 0:00 4/2 3:00 4/2 6:00 4/2 9:00 4/2 12:00 4/2 15:00 4/2 1:00 4/2 21:00 4/29 0:00 6
Reality Differential Metering 11 Differential Metering Example Area2 Area4 Area3 EOS Meter 2+3+4 Vol=4.15 MG Vol=4.00 MG 10 9 DS Meter Flow (cfs) 7 6 5 Sum of DS Deters 4 3 2 1 0 12/1/06 0:00 12/1/06 3:00 12/1/06 6:00 12/1/06 9:00 12/1/06 12:00 12/1/06 15:00 12/1/06 1:00 12/1/06 21:00 12/2/06 0:00 Resulting Incremental Hydrograph 3 Incremental Flow EOS-(2+3+4) 2 1 Flow (cfs) 0-1 06 0:00 12/1/0 06 3:00 12/1/0 06 6:00 12/1/0 06 9:00 12/1/0 6 12:00 12/1/06 6 15:00 12/1/06 6 1:00 12/1/06 6 21:00 12/1/06 06 0:00 12/2/0-2 -3 7
Velocity (fps) 5.0 4.5 4.0 35 3.5 3.0 2.5 2.0 1.5 1.0 0.5-3.5 Using Scattergraphs to Evaluate Meter Problems Area2 Scattergraph - 10 20 30 40 50 60 70 0 Level (in) Area3 Scattergraph Velocity (fps) 2.0 1. 1.6 1.4 1.2 1.0 0. 0.6 0.4 0.2-4.0 Area4 Scattergraph - 10 20 30 40 50 60 70 Level (in) APS1 Scattergraph Velocity (fps) 30 3.0 2.5 2.0 1.5 1.0 0.5 Velocity (fps) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 - - 10 20 30 40 50 60 70 Level (in) - - 1 2 3 4 5 6 Level (in) Impact of Pump Station Recording Interval 2 1. 1.6 1.4 1.2 1 0. 0.6 0.4 0.2 0 LS: 15min Average using 5min instaneous readings US Area1: 5 min instantaneous / / / / / / / / /13 12:00 /13 15:00 /13 1:00 /13 21:00 /14 0:00 /14 3:00 /14 6:00 /14 9:00 /14 12:00 /14 15:00 /14 1:00 /14 21:00 /15 0:00 /15 3:00 /15 6:00 /15 9:00 / / / / /15 12:00 /15 15:00 /15 1:00 /15 21:00 /16 0:00 /16 3:00 /16 6:00 /16 9:00 / / / / /16 12:00 /16 15:00 /16 1:00 /16 21:00 /17 0:00
Level Sensors Lots of focus on velocity measurement but level is as critical Difficult to take manual measurement in field for site calibration Small error can result in large flow impact Must consider depth range being scaled for sensor Rain Gages Needed to correlate inflow response and make flow Needed to correlate inflow response and make flow projections Usually an afterthought Rain gages can malfunction too should have at least two More needed based on size of service area and seasonal storm periods 9
Using Data from Others Obtain sample records before relying on for metering program Confirm format and recording intervals Ask about QA/QC protocols Request site maintenance records, if available Synchronize clocks System Operations System operations can impact monitoring results System operations can impact monitoring results Need to be aware of any activities by others in area Examples: - Diversions or bypasses - Water main breaks - Sewer cleaning Sewer cleaning - Pump station maintenance - Downstream influences 10
Data Collection/Quality Review Start early and review often Interact with field crews to troubleshoot problems Document observations and decisions - Require field reports for site visits - Document site calibrations Case Study of Two Permanent Meter Site Upgrade Projects 1. Wayne County meter site WCS-1 2. Wayne County meter sites WCS-2 and WCS-3 11
12
C1 Meter Replacement Originally to be another magmeter Originally to be another magmeter New technology options evaluated to minimize future replacement costs Selected Accusonic cross-path transit time meter 13
New C1 Accusonic Meter C1 Meter Acceptance 3 rd party dye test included in specifications 3 rd party dye test included in specifications Excellent performance 14
C2 and C3 Meter Replacement Parts no longer available for Sparling Sonic meters Parts no longer available for Sparling Sonic meters Evaluated new technology options Allowed bids for Accusonic or MGD meter MGD meter selected by contractor 15
New C2 MGD Meter New C3 MGD Meter 16
Close up view of MGD Sensor C2 and C3 Meter Acceptance 3 rd party dye tests conducted 3 rd party dye tests conducted C3 meter performed well - C2 meter did not Additional investigations by meter supplier and contractor did not improve result Concern raised for debris in sewer pipe 17
C2 Siphon Cleaning C2 Siphon Cleaning (cont.) 1
C1 Retests Site performed better after siphon cleaning Additional review and adjustments made by manufacture Meters accepted for use with adjustment factors Reality Flow Metering Conclusions Collection system monitoring is not an exact science but Collection system monitoring is not an exact science but technology and analysis methods continue to improve Embrace the new technology but realize it s limitations If you are serious about quality flow metering results you must dedicate appropriate resources Use flow monitoring as an asset management tool 19