ASCE Oregon EWRG Stormwater Monitoring Challenges and Trip-ups in search of the elusive EMC January 25, 2017 Presented by Curtis Nickerson Bryan Berkompas ASCE Oregon EWRG
It’s a challenge! Targeting an ephemeral event Challenge to get representative data Difficult working conditions ASCE Oregon EWRG
Overview Stormwater monitoring basics Planning a monitoring project Site selection consideration Instrument selection and installation Pointers for project implementation ASCE Oregon EWRG
Stormwater monitoring basics Water quality sampling In-situ WQ measurements Flow metering Rain gauging Stormwater sediment sampling ASCE Oregon EWRG
Water quality sampling approaches Manual grab sampling instantaneous measurement Time-paced composite sampling time-averaged concentration Flow-weighted composite sampling event-mean concentration can calculate loading ASCE Oregon EWRG
Monitoring project planning Monitoring infrastructure has typically been an after thought Get in on the facility design process More difficult to retrofit for monitoring ASCE Oregon EWRG
Start planning early! Prepare planning documents Select site(s) Procure equipment and materials Install and test equipment Train staff ASCE Oregon EWRG
Allow yourself 4-6 months to prepare ASCE Oregon EWRG
Before you can implement the project ASCE Oregon EWRG
Monitoring site selection Locations driven by project objectives Characterization Pollutant source tracing Permit compliance BMP effectiveness evaluation ASCE Oregon EWRG
Select sites that isolate flows of interest but provide monitorable conditions ASCE Oregon EWRG
Site selection considerations Access Flow conditions Security Pipe characteristics Future changes to Tidal influence infrastructure Backwater Confined space Permanent site for Traffic control sampling equipment Vandalism Off-site, co-mingled sources Power source Freezing conditions Cell phone access Flooding ASCE Oregon EWRG
Ensure access and security ASCE Oregon EWRG
Flow metering options pressure transducer flume weir bubbler flow meter mag meter Venturi tube meter area-velocity meter look-down sensor ASCE Oregon EWRG
Flow monitoring challenges Channel or pipe slope too steep Water depth too shallow No defined channel Backwater conditions, including tidal effects Large range of flows Straight reaches/ pipe sections too short ASCE Oregon EWRG
Include monitoring in infrastructure design ASCE Oregon EWRG
Include monitoring in infrastructure design flume ASCE Oregon EWRG
Retrofit with primary devices Thelmar weir ASCE Oregon EWRG
Addressing difficult hydraulic conditions foam wedge ASCE Oregon EWRG
Addressing poorly defined channel ASCE Oregon EWRG
Flow monitoring at flow control structures bypass secondary orifice primary orifice measure water level then calculate flow from orifice and weir equations ASCE Oregon EWRG
Custom equipment 3-in. magmeter tipping bucket medium to high flows (max. 160 gpm) trickle and low flows (<1.8 gpm) ASCE Oregon EWRG
Custom equipment secondary drain primary drain ASCE Oregon EWRG
Manual grab sampling Swing arm sampler ASCE Oregon EWRG
Passive grab sampler ASCE Oregon EWRG
Grab sampling from deep manholes extension pole suction from pump sample tubing sample bottle sealed canister ASCE Oregon EWRG
Grab sampling from deep manholes ASCE Oregon EWRG
Catch basin insert sampling ASCE Oregon EWRG
Catch basin insert sampling ASCE Oregon EWRG
Autosampler examples ASCE Oregon EWRG
Addressing high velocity or shallow flows low flow strainer ASCE Oregon EWRG
Customized samplers cubitainer ASCE Oregon EWRG
Customized autosamplers “drum sampler” ASCE Oregon EWRG
Customized autosamplers “drum sampler” ASCE Oregon EWRG
Customized autosamplers “mega sampler” ASCE Oregon EWRG
Rainfall measurement Onsite rage gauge or nearby if accessible real- time Need open area Security a concern ASCE Oregon EWRG
Tipping bucket rain gauge ASCE Oregon EWRG
Tipping bucket rain gauge ASCE Oregon EWRG
Considerations for monitoring station installation Don’t believe design plans – always measure and inspect critical elements Orifice sizes/ condition Weir position Incorrect construction ASCE Oregon EWRG
Considerations for monitoring station installations ASCE Oregon EWRG
Considerations for monitoring station installation ASCE Oregon EWRG
Expect extreme weather ASCE Oregon EWRG
Expect extreme weather ASCE Oregon EWRG
Tips for “hardening” monitoring stations Sturdy housing Concrete pad or wooden platform Conduit for electrical cable and suction line (below ground if vehicle traffic present) Anchor housing if security a concern Seal gaps to exclude rodents and insects Stainless steel fasteners if zinc a concern Use “quick connects” for sampler suction line Use zip- ties to organize cables “in the hole” Keep suction line and electrical cables out of flow line to protect from debris ASCE Oregon EWRG
“Un - hardened” monitoring station ASCE Oregon EWRG
“Hardened” monitoring station ASCE Oregon EWRG
“Hardened” monitoring station ASCE Oregon EWRG
“Hardened” monitoring station ASCE Oregon EWRG
Above ground installation preferred, but sometimes not possible. Manhole hanger ASCE Oregon EWRG
Underground installation ASCE Oregon EWRG
Telemetry is a game changer! Provides remote control of samplers and flow meters Frequent automatic downloading of data on a set schedule We use Campbell Scientific data logger/controllers for flexibility with instrumentation and programming Communicate via cellular, radio, and even satellite option ASCE Oregon EWRG
Benefits of telemetry Reduced labor to arm samplers prior to storm events Ability to modify instrument settings remotely immediately prior to or during a storm One person (Storm Controller) can monitor status of numerous stations concurrently Automatic notifications based on alarm settings Field staff deployed only as-needed ASCE Oregon EWRG
Insert screen shot of logger net Loggernet connect screen ASCE Oregon EWRG
Targeting a storm with telemetry sdn1-tele Flowlink 4 for Windows L eve l (1.90 6 ft) Ra in fa ll (0 .0 8 in) Sa mp le (1 .4 54 7 m) 2 .0 1 .9 ft 1 .8 0 .0 10 0 .0 05 in 0 .0 00 4 2 m 0 3 PM 6 PM 9 PM 7 Su n 3 AM 6 AM 9 AM 6 Sa t O ct 2 0 07 1 0/6/20 0 7 2:00 :0 0 PM - 1 0/7/20 0 7 11 :0 0 :00 AM ASCE Oregon EWRG
Tips for data collection phase Make sure you have sufficient, well trained staff Train for confined space entry, instrument operation, sample collection and handling methods Rotate storm response assignments – make schedules as predictable as possible Be ready to improvise! Storms rarely occur as advertised Equipment malfunctions People make mistakes ASCE Oregon EWRG
Tips for data collection phase Develop and use SOPs for everything Detailed field sheets – completely filled out! Double check equipment Ice samples immediately and thoroughly Be safe! – often dark, wet, cold and windy ASCE Oregon EWRG
ASCE Oregon EWRG
Sample processing options Decaport sample splitter for sample compositing/ splitting ASCE Oregon EWRG
Sample processing options Churn sample splitter to fill bottles for laboratory analysis ASCE Oregon EWRG
Hydrologic data QC actions Conduct routine maintenance and calibration Download and check flow and rainfall data regularly Is it believable? If not, investigate Check instrument performance Check site for potential causes of strange data ASCE Oregon EWRG
Check instruments Rain gauge calibration check ASCE Oregon EWRG
Check instruments Secondary flow measurement ASCE Oregon EWRG
Water quality QC actions Collect field and trip blanks routinely Backflush sampler tubing thoroughly Replace sampler tubing periodically Adjust laboratory decon procedures if necessary Raise sampler strainer out of baseflow/sump between sampling events ASCE Oregon EWRG
Questions? Curtis Nickerson cnickerson@aspectconsulting.com 206.838.8595 www.aspectconsulting.com ASCE Oregon EWRG
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