Stormwater Program for Industrial Activity: Steps to Compliance

Step 10: Sampling

Step 10a View guidance materials

For answers to commonly asked questions about industrial stormwater sampling requirements, read and download the Industrial Stormwater Sampling FAQ (wq-strm3-35) .

View the Industrial Stormwater Sampling Videos

• How to Collect a Sheet Flow Sample, YouTube Video
  • Industrial Stormwater Sheet Flow Sampling Guidance Document (wq-strm3-33a)
• How to Collect a Grab Sample, YouTube Video
  • Grab Sample Guidance Document, September 2011 (wq-strm3-33b)

Check out the Monitoring Guidance Manual For Minnesota’s Industrial Stormwater Multi-Sector General Permit (wq-strm3-27) (12/10) to learn the answers to these questions:

• Who needs to monitor?
• What do I need to monitor
• When do I take my sample?
• Where do I take my samples?
• How do I sample?
• How do I report my sampling results?

Step 10b: Work with a testing laboratory

Facilities may use any MN Department of Health Certified Testing Laboratory to conduct analyses required by the permit:

• MN Department of Health Certified Testing Labs
  

Questions for the lab

• Is the lab MN Department of Health certified for the analyses that are needed?
• Can this lab analyze the parameters needed?
• Can the Lab achieve the required reporting levels?
• What is the price of analyzing my samples?
• What are the bottle delivery responsibilities?
• What are the holding time/turnaround times?
• What is the reporting methodology?
• Can the laboratory help me with questions, such as how to take samples or help in getting sample bottles to me?
• Where is the lab located and are they available to help me with my sampling needs?

Steps for working with a lab

1. If you have never ordered bottles from a lab before, contact the lab before you are planning on conducting the stormwater sampling event.  Be sure to have:
   • Your name, company/organization name, address, phone number and email address
   • Additional contacts that you want the final report and/or Invoice sent to
   • Number of samples/monitoring locations for your facility. 
   • Your subsector(s), including the parameters you have to monitor for
   • Any special issues of concern (e.g. scheduling tests with short holding times, site-specific reporting limits, additional permit requirements, etc
2. Generally speaking, once the initial bottle order has been set up, bottles will arrive in a few days.
3. Once the bottles arrive and a qualifying storm event occurs:
   • Fill the bottles according to the lab instructions
   • Place bottles in the cooler
   • Complete any remaining required sections of the Chain of Custody
4. After packing the cooler:
   • Arrange for the delivery to the lab if you haven’t already (NOTE: Nitrate + Nitrite samples must be received within 48 hours of the sample collection)
   • Consider local courier services (such as Speedee or Elite Transportation) or National courier (such as FedEx or UPS), or drop off in person
5. Once samples are received by the laboratory:
   • Allow up to 10 business days for sample results
   • Results are generally sent to the permittee

Information about these steps was adapted from Pace Analytical “Steps for Placing a New or First Time Bottle Order” document.

Step 10c: Read the overview to stormwater sampling requirements

All Permittees are required to conduct stormwater sampling at their facility.  Facilities with effluent monitoring requirements must conduct, at a minimum, a once-per-calendar-year stormwater sample. Facilities with benchmark monitoring requirements begin sampling in “year 2” of their permit cycle (the permit cycle is based on the date the facility applied for and received permit coverage). 

Benchmark monitoring information

Benchmark Monitoring is required by all facilities and the first sampling interval begins one entire year after the facility receives permit authorization from the MPCA.  For example:

• Facility A received permit coverage on August 5, 2010 and has no effluent monitoring requirements
• The first benchmark sampling interval begins on August 5, 2011.  For Facility A, their sampling intervals are:
  • August 5-November 4, 2011
  • November 5, 2011-February 4, 2012
  • February 5, 2012- May 4, 2012
  • May 5, 2012-August 4, 2012

Benchmark monitoring location definition

The benchmark monitoring location(s) shall be in a location that:

• Is below the most down-gradient BMP from the source of industrial activity or significant materials, but prior to discharging from the permittee’s operational control.
• Minimizes or eliminates sampling of stormwater from offsite sources (run-on), and,
• Yields a sample that best represents the contribution of pollutants the permittee is required to monitor for that discharge from an area of industrial activities, processes, and significant materials exposed to stormwater.

Substantially similar definition

If the Permittee has identified multiple, but separate, stormwater discharges associated with industrial activity, and each area of discharge is substantially similar in terms of exposure, BMPs, and pollutants discharged, the Permittee may choose one benchmark monitoring location that is most representative and best allows for obtaining a sample. Note: If you have different activities or materials, or different BMPs to manage the activities and materials, you cannot utilize the "substantially similar" definition.

Step 10d: Confirm your previously chosen monitoring locations

Not sure if you chose the correct monitoring locations?  Check out the Benchmark and effluent monitoring location diagrams for all sectors (wq-strm3-29) fact sheet to confirm or choose different monitoring locations.  The next time it rains or there is snow melt runoff, confirm that industrial stormwater is discharging where you think it does, as indicated on your facility map and on the application form.  If there is a change in a monitoring location, be sure to update your facility map and notify the Industrial Stormwater Program by filling out the Industrial Stormwater Administrative Change Form (PDF Version) (wq-strm3-60) .

If a facility passes their benchmark monitoring requirements in “year 2” of the permit cycle, they are done with sampling requirements for the life of this Industrial Stormwater permit.  If a facility does not pass their benchmark monitoring requirements, modify or choose new BMPs, update your SWPPP, and sample again in “year 4” of the permit cycle.  Facilities that still do not pass their benchmark monitoring requirements sample again in “year 5” of the permit cycle.

NOTE:  An exceedance of a benchmark value is not a violation under the permit. However when an exceedance occurs, the facility is required to perform corrective actions to address stormwater control measures, including the maintenance or implementation of BMPs. Failure to respond to benchmark value exceedances is a violation.

Benchmark monitoring video

Watch the “How to Choose and Confirm Monitoring Locations” Youtube Video, completed November 2010.

Step 10e: Determine if you have effluent monitoring requirements 

4% of Permittees also have industrial stormwater Effluent Monitoring Requirements. Is this you? This is a once-per-year, every year of the permit cycle. If you are required to comply with these requirements but had no off-site surface water discharges, you are still required to submit the Discharge Monitoring Report form to the MPCA; be sure to provide an explanation within the "If NO flow occurred during monitoring period, explain why" box and mail the form to the MPCA.

NOTE:  Facilities who do not pass their effluent monitoring limits, it is a violation.  The Permittee need to make every effort to verify the violation by collecting additional samples; if appropriate, investigate the cause of the violation and take action to prevent future violations. Violations that are determined to pose a threat to human health or a drinking water supply, or represent a significant risk to the environment shall be immediately reported to the MN Duty Officer at 1-800-422-0798 or 651-649-5451. In addition, the Permittee may also contact the Agency during business hours. Otherwise, the violations and the results of any additional sampling should be recorded on the next appropriate DMR or report.

Here’s a list of facility types required to conduct effluent monitoring:

• Sector A: Discharges from wet decking storage areas
• Sector C: Runoff from phosphate fertilizer manufacturing facilities that comes into contact with any raw materials, finished product, by-products or waste products (SIC code 2874)
• Sector D: Runoff from asphalt emulsion facilities
• Sector E: Runoff from material storage piles at cement manufacturing facilities
• Sector J: Mine dewatering discharges at construction sand and gravel, or industrial sand mining facilities
• Sector K: Runoff from hazardous waste landfills
• Sector L: Runoff from non-hazardous waste landfills
• Sector O: Runoff from coal storage piles at steam electric generating facilities

Effluent monitoring location

The effluent monitoring location(s) shall be in a location that:

• Is immediately below the most down-gradient BMP from the specific industrial activity that has a numeric effluent limit, but prior to where the discharge co-mingles with stormwater from other sources.
• Yields a sample that represents the contribution of the pollutants the permittee is required to monitor for that discharges from an area of industrial activities, processes, and significant materials exposed to stormwater that has a numeric effluent limit.

This means by the end of this year (by December 31, 2011), one sample must be collected, analyzed, and results submitted for effluent monitoring. See part VI of the Multi-Sector General Permit for more information on Effluent Monitoring Requirements.

Step 10f: Determine when to sample

Permittees can take a stormwater sample anytime there is a measurable runoff event, which means any volume allowing a Permittee to obtain a sample. The Permittee should take samples within 30 minutes of the start of a measurable discharge but if they are unable to, still collect a sample and record on the SWMR why a sample could not be collected within the first 30 minutes of a measurable runoff event. The permit requires that the storm event you are going sample be preceded by at least 72 hours with no previous rainfall (greater than trace precipitation).

Winter thaw storm event

Because the Permittee is required to collect four benchmark samples in separate three month intervals, winter thaw sampling will occur and is often obtainable, as it had been during the 2010, 2011 and 2012 winters state-wide.  Thaws of snow accumulations have the potential to carry significant accumulations of site pollutants offsite.  Winter thaws are when snow and ice cover melt, which usually occurs when temperatures are greater than 32ºF for two or more days.

Step 10g: Obtain equipment required for sampling

• Flashlight (non-sparking)          
• Hard Hat
• Safety Goggles
• Reflective Vests
• Gloves(Latex or Nitrile)
• Rain Gear
• Safety Shoes
• Traffic Cones
• Rain Gauge
• Eye Wash Bottle
• Paper Towels  
• Ice Cooler/Shipping Cooler
• Field Sampling Notebook
• Waterproof Pens
• pH meter
• Sampling Bottles
• Preservatives   
• Waterproof Labels      
• First Aid Kit

Step 10h: Read other sampling manuals

Note: other states’ requirements may differ from Minnesota’s, so be sure to verify Minnesota’s regulations if you utilize another state’s guidance information.

• EPA:  Guidance Manual for the Monitoring and Reporting Requirements of the NPDES Stormwater Multi-Sector General Permit (1999)
• Vermont:  Stormwater Sampling for the Vermont Multi-Sector General Permit: A Guide for Industrial Facilities (2007)
• Washington: How To Do Stormwater Sampling-A guide for industrial facilities (2009)
• Portland: Stormwater Monitoring for Industry (2007)
• Ohio: Industrial Stormwater Monitoring and Sampling Guide (2009)

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