Stormwater Monitoring Challenges and Trip-ups in search of the - - PowerPoint PPT Presentation

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Stormwater Monitoring Challenges and Trip-ups in search of the - - PowerPoint PPT Presentation

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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 Its a challenge! Targeting an ephemeral event Challenge

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ASCE Oregon EWRG

Stormwater Monitoring Challenges and Trip-ups

in search of the elusive EMC

ASCE Oregon EWRG

Presented by

Curtis Nickerson Bryan Berkompas

January 25, 2017

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It’s a challenge!

 Targeting an ephemeral event  Challenge to get representative data  Difficult working conditions

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Overview

 Stormwater monitoring basics  Planning a monitoring project  Site selection consideration  Instrument selection and installation  Pointers for project implementation

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Stormwater monitoring basics

 Water quality sampling  In-situ WQ measurements  Flow metering  Rain gauging  Stormwater sediment sampling

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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

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Monitoring project planning

 Monitoring infrastructure has typically

been an after thought

 Get in on the facility design process  More difficult to retrofit for monitoring

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Start planning early!

 Prepare planning documents  Select site(s)  Procure equipment and materials  Install and test equipment  Train staff

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Allow yourself 4-6 months to prepare

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Before you can implement the project

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Monitoring site selection

 Locations driven by project objectives

 Characterization  Pollutant source tracing  Permit compliance  BMP effectiveness evaluation

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Select sites that isolate flows of interest but provide monitorable conditions

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Site selection considerations

 Access  Security  Future changes to

infrastructure

 Confined space  Traffic control  Vandalism  Power source  Cell phone access  Flooding  Flow conditions  Pipe characteristics  Tidal influence  Backwater  Permanent site for

sampling equipment

 Off-site, co-mingled

sources

 Freezing conditions

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Ensure access and security

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Flow metering options

flume weir bubbler flow meter pressure transducer look-down sensor area-velocity meter Venturi tube meter mag meter

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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

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Include monitoring in infrastructure design

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Include monitoring in infrastructure design

flume

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Retrofit with primary devices

Thelmar weir

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Addressing difficult hydraulic conditions

foam wedge

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Addressing poorly defined channel

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Flow monitoring at flow control structures

primary orifice secondary orifice measure water level then calculate flow from orifice and weir equations bypass

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Custom equipment

3-in. magmeter

medium to high flows (max. 160 gpm)

tipping bucket

trickle and low flows (<1.8 gpm)

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Custom equipment

secondary drain primary drain

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Manual grab sampling

Swing arm sampler

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Passive grab sampler

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Grab sampling from deep manholes

suction from pump

sealed canister

sample bottle sample tubing extension pole

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Grab sampling from deep manholes

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Catch basin insert sampling

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Catch basin insert sampling

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Autosampler examples

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Addressing high velocity or shallow flows

low flow strainer

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Customized samplers

cubitainer

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Customized autosamplers

“drum sampler”

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Customized autosamplers

“drum sampler”

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Customized autosamplers

“mega sampler”

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Rainfall measurement

 Onsite rage gauge or nearby if accessible real-

time

 Need open area  Security a concern

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Tipping bucket rain gauge

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Tipping bucket rain gauge

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Considerations for monitoring station installation

 Don’t believe design plans – always measure

and inspect critical elements

 Orifice sizes/ condition  Weir position  Incorrect construction

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Considerations for monitoring station installations

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Considerations for monitoring station installation

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Expect extreme weather

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Expect extreme weather

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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

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“Un-hardened” monitoring station

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“Hardened” monitoring station

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“Hardened” monitoring station

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“Hardened” monitoring station

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Above ground installation preferred, but sometimes not possible.

Manhole hanger

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Underground installation

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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

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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

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Insert screen shot of logger net Loggernet connect screen

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Targeting a storm with telemetry

1 .8 1 .9 2 .0 .0 00 .0 05 .0 10 2 4 3 PM 6 Sa t O ct 2 07 6 PM 9 PM 7 Su n 3 AM 6 AM 9 AM

sdn1-tele

Flowlink 4 for Windows ft in m 1 0/6/20 7 2:00 :0 0 PM - 1 0/7/20 7 11 :0 :00 AM L eve l (1.90 6 ft) Ra in fa ll (0 .0 8 in) Sa mp le (1 .4 54 7 m)

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Tips for data collection phase

 Make sure you have sufficient, well trained

staff

 Train for confined space entry, instrument

  • peration, 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

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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

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Sample processing options

Decaport sample splitter for sample compositing/ splitting

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Sample processing options

Churn sample splitter to fill bottles for laboratory analysis

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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

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Check instruments

Rain gauge calibration check

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Check instruments

Secondary flow measurement

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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

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Questions?

Curtis Nickerson

cnickerson@aspectconsulting.com 206.838.8595 www.aspectconsulting.com