Wet Weather Sampling to Fulfill MS4 NPDES Permit Requirements run, run fast, run away now

1. Wet Weather Sampling to Fulfill MS4 NPDES Permit Requirementsrun, run fast, run away now Annette DeMaria, P.E. Staff Engineer Environmental Consulting & Technology, Inc. Michigan Water Environment Association Phase I and II Storm Water Permitting Workshop December 9, 2009

2. 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.

3. What do these terms have in common? • Act naturally • Almost perfect • Jumbo shrimp • One representative sample They are all oxymorons

4. Presentation Focus • Findings areas/sources of elevated E. coli/ Phosphorus via wet weather sampling (while fulfilling the permit requirements)

5. 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

6. Determine your Budget • Internal resources • Expertise • Field personnel • Equipment • Lab services • External resources • Consultants

7. Define the Area of Interest • Watershed • Sub-watershed • Sub-basin • Jurisdiction

8. Various Monitoring Approaches • Stream/tributary monitoring • If you have limited data telling you where to focus your efforts • Discharge point monitoring • To identify which outfalls to investigate in a previously defined problem area • In-system (investigative) monitoring • To further narrow down the source area, if you know any outfall is “hot”

9. 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

10. Example Load Duration Curve http://www.ehow.com/how_5148881_create-load-duration-curve.html Percent of time the flow was exceeded

11. Example Load Duration Curve

12. 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

13. Wet Weather Sampling Program Elements • Patience • Luck

14. 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

15. 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

16. 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

17. 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

18. Number of Sampling Events • Minimum: 5 at a site • 1 year • Preferred: 10 or as many as possible • 2 years

19. Number of Samples per Event • Minimum = 6 • 2 on the rising limb of the hydrograph • 2 at the peak • 2 on the falling limb

20. Example Hydrograph for Surface Runoff

21. Example Hydrograph for Surface Runoff

22. Example Hydrograph for Surface Runoff

23. 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 collection verses Composite

24. 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

25. 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

26. Analyzing Data: Dry vs Wet Weather

27. Analyzing Data: Median Phosphorus Conc. (mg/L) Dry Wet 0.02 0.03 0.14 0.08 0.02 0.36 0.07 0.08 0.31 0.02 0.19 0.26 0.14 0.14 0.23 0.05 0.46 0.62 0.14 0.42 US EPA’s recommended limit: 0.033 mg/L

28. Analyzing Data: Box & Whisker Plot

29. Analyzing Data: Frequency Distribution Based on daily geometric mean values (cfu/100 mL)

30. 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

31. Questions? Annette DeMaria ademaria@ectinc.com 586-465-2583