Hydrant Flow Testing for Hydraulic Model Calibration. Doug Lane, PE City of Bellevue, WA

Transcription

1 Hydrant Flow Testing for Hydraulic Model Calibration Doug Lane, PE City of Bellevue, WA

2 Background Service Area 140,000+ Population 135,000+ Jobs 61 Pressure Zones Separated Sewers Hydrant Testing 70 Sites Re building model Re calibrating

3 Calibration What is calibration? 1. Field Testing (measure flow & pressure drop) 2. Run Model 3. Adjust Model to match field conditions AWWA M32

4 Benefits Why Calibrate? Modeling Accuracy Reduced Risk Insurance Ratings Verify proper operation (valve positions, PRV settings, etc)

5 Site Selection Flow Hydrant Selection More pressure drop = Better Data Prioritize high value/ high density Geographical Coverage

6 Site Selection Residual Pressure Monitoring Location Measure biggest anticipated pressure drop Not necessarily nearest hydrant Pay attention during test

7 Site Selection Dead end example: WATER SOURCE RESIDUAL PRESSURE PARTIAL DROP = INCOMPLETE PICTURE STATIC PRESSURE??? ERROR RANGE NEAREST HYDRANT FLOW HYDRANT

8 Site Selection Dead end example: STATIC PRESSURE WATER SOURCE RESIDUAL PRESSURE FULL PRESSURE DROP = BETTER DATA NEAREST HYDRANT FLOW HYDRANT METER OR BLOWOFF

9 Site Selection Remote Residual Pressure Monitoring Continuous Data (but can t see until later) Broader view across zone(s) Both sides of PRVs Hydrant testing requires significant labor get the best data you can, while you can

10 Site Selection Pressure (psi) Pressure Recording Upstream of PRV Sec Recording 70 1 Min Average :33 AM10:40 AM10:48 AM10:55 AM11:02 AM11:09 AM11:16 AM Time 2/14/2014 Pressure (psi) Pressure Recording at FH Sec Recording Min Average :08 AM 11:25 AM 11:42 AM 12:00 PM 12:17 PM 12:34 PM Time 11/15/2013 Pressure (psi) Pressure Recording at FH Sec Recording Min Average 45 8:49 AM 9:01 AM 9:12 AM 9:24 AM 9:36 AM 9:47 AM 9:59 AM 10:10 AM Time 1/14/2014

11 Site Selection Field Reconnaissance: Down sloping driveways? Drainage Capacity Curbs? Ditches? Small creeks? If risk is significant, pick another site!

12 Site Selection Don t do this:

13 Site Selection Assess neighborhood impacts: Traffic (need to close lane? off hours?) Business access or disruption Schools Distraction (create a scene?)

14 Minimum Pressure Critical low pressure locations Not necessarily at the flow site Review topography, connectivity Know the limits ahead of time Keep an eye on gauge during test

15 Public Notification What will happen When Why What to expect What to do in case of problem Who to call

16 Site Preparation Before After

17 Communications Constant radio communication Logistics during setup Report problems Flow/pressure readings Have some spares!

18 Documentation Clear data to reconstruct test in model CYA in case of questions/complaints

19 Downstream Water Quality Separated storm sewers Salmon spawning streams NPDES permit requirements

20 Downstream Water Quality Street Sweeping Catch Basin Cleaning Dechlorination: Vita D Chlor

21 Erosion Control Tarps, Dispersion, etc

22 Stream Stabilization Off site drainage BMPs Straw wattles, silt fences, etc

23 Property Protection Keep water in the ROW! Set up beneficial hose angle, length Use both sides of street Sandbags Booms Other devices

24 The Drainage Demon Neighbors Taking the Trash Out The Drainage Demon in Action

25 Gimmicks & Gadgets Santa Pants Re purposed Signs Truck Tire Drainage BMP

26 Peak Flow When to stop increasing flow: Drainage: Risk of Property Damage Pressure: Residual Pressure at Minimum (anywhere in zone; not necessarily at site) Velocity: Max Velocity (especially AC mains) Capacity: Ports fully open

27 System Water Quality Notify WQ staff of test ahead of time Review flushing history Allow time for flush after test

28 Safety Hazards: Open grates Open manholes, Exposed actuators Low visibility Traffic Crime Ice

29 Safety Mitigation: Signage and Cones Lighting PPE Vehicles as barricades Extra crew when needed Monitor weather

30 Overnight Work Required when: Arterial Lane Closures Potential Business Impacts (traffic access, WQ, etc) Anything Downtown Testing at Bellevue Galleria

31 Overnight Work Bellevue Branch of King County Library

32 Public Interaction

33 Fire Alarm Coordination Potential false alarms Particularly problematic downtown (4:00 am; dense residential towers!!!).

34 Fire Alarm Coordination Outreach with building owners near test Systems in test mode; fire watch required Notify Fire Dept: Dates Times Test Location Addresses

35 Workload and Level of Effort Minimum 2 operators, 1 engineer at each test Additional staff when needed Average Flow Test: 28 hours O&M 6 hours Engineering

36 Results Major problems identified and corrected: One PRV station isolated Another large PRV would not open Some PRV stations needed minor adjustment Identified broken hydrant, broken foot valve

37 Results No known customer complaints No property damage (one close call) Did not encounter significant valve closures (system operated as intended)

38 Recommendations Incorporate data into model per AWWA M32 Consider flow testing as an integral part of the flushing program Perform testing after significant system changes

39 Questions?