Wet Weather Sampling to Fulfill MS4 NPDES Permit Requirements run, run fast, run away now
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Transcript of Wet Weather Sampling to Fulfill MS4 NPDES Permit Requirements run, run fast, run away now
Wet Weather Sampling to Fulfill MS4 NPDES Permit Requirements
run, run fast, run away now
Annette DeMaria, P.E. Staff EngineerEnvironmental Consulting & Technology, Inc.
Michigan Water Environment AssociationPhase I and II Storm Water
Permitting WorkshopDecember 9, 2009
Permit Requirements (Watershed Permit)
• Standard Approach– Collect 1 representative sample from 50% of major discharge
points w/in the TMDL portion of the urbanized area.– Use this information to identify actions to reduce E.
coli/Phosphorus. – Or if data is available
• Submit an existing plan that prioritizes areas and actions for controlling the pollutant
• Elective Option– Work collaboratively to develop and implement a monitoring
program to determine priority areas requiring further actions.
What do these terms have in common?
• Act naturally• Almost perfect• Jumbo shrimp• One representative sample
They are all oxymorons
Presentation Focus
• Findings areas/sources of elevated E. coli/ Phosphorus via wet weather sampling (while fulfilling the permit requirements)
Review Available Data
Should help determine where to focus efforts, potential sources and elements of your sampling plan
• Ambient water quality and quantity data– Watershed studies– Beach data– USGS flow data– TMDL data
• IDEP data
Determine your Budget
• Internal resources– Expertise– Field personnel– Equipment– Lab services
• External resources– Consultants
Define the Area of Interest
• Watershed• Sub-watershed• Sub-basin• Jurisdiction
Various Monitoring Approaches
1. Stream/tributary monitoring– If you have limited data telling you where to focus
your efforts2. Discharge point monitoring
– To identify which outfalls to investigate in a previously defined problem area
3. In-system (investigative) monitoring– To further narrow down the source area, if you
know any outfall is “hot”
Sampling Approaches
• Collect routine data and evaluate against stream flow conditions– More data intensive, but less staff intensive– Create load duration curves to determine the
weather/stream conditions associated with the impairment
• Collect wet weather data only– Very, very, very, very resource intensive
Load Duration Curve for Ecorse River At Sampling Station EC5Data Collected from 5/1/2007 to 10/2/2007
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
1.0E+13
1.0E+14
1.0E+15
0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%
Load Duration Interval (%)
Dai
ly L
oad
(# E
. col
i/Day
)
300 cfu/100 ml 1000 cfu/100 ml 2007 Data Daily Geomean
High Flows Moist Conditions Mid-Range Flows Dry Conditions Low Flows
Example Load Duration Curvehttp://www.ehow.com/how_5148881_create-load-duration-curve.html
Percent of time the flow was exceeded
Example Load Duration Curve
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 100
1,000
10,000
100,000
DO Readings expressed in lb/hr 5 mg/L FERC Permit Limit
Percentage of Time the indicated Flow was Equaled or Exceeded in 2009
Diss
olve
d O
xyge
n Lo
ad (l
b/hr
)
Low Flow RangeMid Flow RangeHigh Flow Range
Values below the red line indicate a permit exceedence
If collecting one sample
• Decide on weather conditions: wet or dry• Tackle dry weather issues first
– It is easier and they compound wet weather problems
Wet Weather Sampling Program Elements
• Patience• Luck
Write a Sampling Plan to Define the…
• Goals of the data collection effort• Staff responsibilities• Sampling locations• Number of sampling events• Sample collection conditions, equipment, methods
and frequency (samples per event)• QC sample frequency• Analytical methods• Data analyses to be performed
Sample Collection Options Automatic Sampling
• Considerations– Power source and sustainability
• NiCad battery• Marine battery• Solar panel vs battery change out
– Enable conditions• Exceedence of a threshold (flow, rainfall or an insitu parameter)• Manual trigger• Time trigger
– Sample pacing• Timed, Flow-weighted
– Sample bottling• Composite, discrete, combination of both
– Equipment maintenance
Sample Collection OptionsManual Sampling
• Considerations– Staff availability
• # of staff needed will depend on the # of sampling locations• Make sure you cover holidays, nights and weekends
– When to mobilize?• Smaller drainage areas: At the onset of the rain• Larger drainage areas: After a response in the hydrograph
– Sample pacing• Timed, usually a function of the number of available staff
– Sample bottling• Composite, discrete, combination of both
Parameters
• Conducting the sample collection is most of the work; why not kill 2 birds with 1 stone?
• Add other analytes that may help with diagnosing the source
• E. coli and Total Phosphorus– BOD, SOD, COD, DO, TSS, ortho-phos, nitrogen
series, chloride, surfactants, etc.– Bacterial source tracking
Number of Sampling Events
• Minimum: 5 at a site– 1 year
• Preferred: 10 or as many as possible– 2 years
Number of Samples per Event
• Minimum = 6– 2 on the rising limb of the hydrograph– 2 at the peak– 2 on the falling limb
Example Hydrograph for Surface RunoffStormFilter
Hydrograph for Storm 1 on 6/21/02
0
0.2
0.4
0.6
0.8
1
1.2
6/21/02 6:45 6/21/02 7:15
Date and time
Dis
char
ge (c
fs)
0
0.1
0.2
0.3
0.4
0.5
0.6
Cum
ulat
ive
Rai
nfal
l (in
)
Inlet DischargeInlet SamplesOutlet DischargeOutlet SamplesRainfall
Example Hydrograph for Surface RunoffStormFilter
Hydrograph for Storm 2 on 7/08/02
0
0.5
1
1.5
2
2.5
3
3.5
7/8/02 21:15 7/8/02 21:45 7/8/02 22:15 7/8/02 22:45 7/8/02 23:15
Date and time
Dis
char
ge (c
fs)
0.0
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Cum
ulat
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nfal
l (in
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Inlet DischargeInlet SamplesOutlet DischargeOutlet SamplesRainfall
Example Hydrograph for Surface RunoffStormFilter
Hydrograph for Storm 16 on 09/14/03
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0.1
0.2
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9/14/035:15
9/14/035:45
9/14/036:15
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9/14/037:15
9/14/037:45
9/14/038:15
9/14/038:45
9/14/039:15
9/14/039:45
9/14/0310:15
9/14/0310:46
9/14/0311:16
9/14/0311:46
9/14/0312:16
Date and time
Dis
char
ge (c
fs)
0
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0.1
0.15
0.2
0.25
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0.35
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0.45
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Cum
ulat
ive
Rai
nfal
l (in
)
Inlet DischargeInlet SamplesOutlet DischargeOutlet SamplesRainfall
Discrete vs Composite
• For composite samples– Flow weight during sample collection– Flow weight after sample collection using stream
flow data. This allows you to select specific samples.
• Use discrete samples– For E. coli
Discrete sample collectionverses
Composite
Quality Control Samples
• Duplicates and blanks: 1 in 20• Collect in the same manner as site sample• To determine precision calculate the relative
percent difference (RPD). – For Phosphorus
• RPD=[(difference of 2 values)/(mean of 2 values)] x 100%• RPD should be ≤ 20%
– For E. coli• Refer to Standard Methods for the Examination of Water and
Wastewater
Preservation and Hold Times
• Total Phosphorus– Sulfuric acid to pH = 2 and ice to 4°C– HT = 28 days
• E. coli– Ice to 4°C– HT = 6 hours for regulatory samples or up to 24
hours for non-regulatory samples
Analyzing Data: Dry vs Wet Weather
Analyzing Data: Median Phosphorus Conc. (mg/L)
Dry
0.02 0.360.08
0.23
0.62
0.05
0.190.07
0.02
0.03
0.08
0.02 0.260.14
0.46
0.42
0.14
0.14
0.14
0.31
Wet
US EPA’s recommended limit: 0.033 mg/L
Analyzing Data: Box & Whisker Plot
Analyzing Data: Frequency Distribution<= 300 301 - 1,000 1,001 - 10,000 > 10,000
Based on daily geometric mean values (cfu/100 mL)
<= 300 301 - 1,000 1,001 - 10,000 > 10,000
Summary
• Wet weather sampling is very labor intensive by automatic or manual means
• Clearly define the objectives of the sampling on the onset
• Plan for hiccups in your sampling plan• And keep in mind, you will never be able to
sleep through a rain event again