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tinyURL : nwqh1121 | ID : 1156Home   >   Water   >   Water Types and Programs   >   Stormwater   >   Industrial Stormwater   >   Industrial Stormwater - Steps to Compliance

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Stormwater Program for Industrial Activity: Steps to Compliance

Step 12: Modify/add new BMPs, if needed

Did your sampling results exceed Benchmark Monitoring requirements?  If so, this step is for you!

New!  Check out these two Sampling Guidance Tools:

If you had an exceedance of one or more of your monitoring parameters after the end of “year 2" monitoring, or did not collect any sample results within “year 2,” you will have to make modifications to your structural and non-structural BMPs and update your SWPPP in "year 3" (for those with exceedances) before taking stormwater samples again in "year 4." You may need to upgrade or add different BMPs, based on those monitoring results.

Note: There are no required "year 3" benchmark sampling requirements. Permittees may choose to sample in “year 3” to see how newly installed BMPs are working. Sample results do not need to be mailed to the MPCA and if they are mailed in, the results will not count toward “year 2” or “year 4” sampling requirements.

Industrial Stormwater Step 12 Benchmark Process

Benchmark monitoring and discharges to impaired waters or Outstanding Resource Value Waters

Does your facility discharge to an impaired water or an Outstanding Resource Value Water (excluding wetlands) and exceeded one or more of your monitoring parameters? If so, do the following:

  • No later than 30 days past the discovery of the exceedance, modify your SWPPP and document all corrective actions, including improvements to BMPs, necessary to meet the applicable benchmark values during fourth year monitoring. Also include any changes in BMPs and the timeframe for implementation of all corrective actions. Modifications and upgrades of the SWPPP should be within this time frame
  • No later than 60 days after discovery of the exceedance, implement necessary non-structural BMPs.
  • No later than 180 days after discovery of the exceedance, implement structural BMPs. If you are unable to complete implementation of structural BMPs within 180 days, submit a plan to the Agency that includes justification why this requirement cannot be met and a specific schedule for completion. The plan shall be submitted no later than 180 days after discovery of the exceedance.

How do I modify/add new BMPs?

Step 12a: Determine which parameters you will be required to re-sample for.

Step 12b: Identify the significant material or industrial activity that the exceedance is connected to. Consider:

  • What BMPs you can modify and change at your facility?
  • Can you move that material or conduct that activity indoors or within a permanent, storm-resistant shelter?
  • If not, are there other BMPs you can add to minimize or eliminate the contaminants of concern?

Example: If a facility has a stockpile of rusted metal, and the previous BMP of routine sweeping of rusted metal parts didn’t allow the facility to pass their benchmarks because of this material and this BMP, they could consider putting the rusted metal into a covered dumpster or other container so that run-on of stormwater does not come into contact with these materials. If precipitation still falls into an open dumpster; be sure to keep the dumpster closed and holes plugged.

What other areas may be causing you to not pass your benchmark monitoring requirements? What different structural and/or non-structural BMPs may help pass your benchmark monitoring requirements?

Step 12c: The Industrial Stormwater BMP Guidebook offers pollutant-specific BMP options.

Step 12d: View links and documents for each sector within the Step 7: Sector-specific requirements, guidance Web page.

Step 12e: The following BMPs have helped many Permittees and may be applicable to your facility, even if you are within a different sector or managing different pollutants.

NOTE:  These suggestions are facility specific and may not work for all permittees with similar problems. Consider non-structural or simple structural BMPs first.


Pollutant-specific- exceedance

Guidance & Suggestions




Solids, Total Suspended (gravel parking lots)

You currently have Class 5 gravel. Options include:

  • Replace it with a swath of rip rap
  • Replace it with washed gravel
  • Pave even part of the area
  • Berm the area before the discharges go offsite
  • Install/manage a pond and an infiltration system to allow the water to filter/settle before discharging offsite
  • Lower the grade to that area so the stormwater ponds before discharging off-site
  • Install/maintain a 4-6’ vegetative buffer strip. A prairie mix of vegetation is preferred though even sod will help

Sector A, Timber Products

Chemical Oxygen Demand

  • Address any decaying wood pallets (and other wood products/waste), look for other decaying materials. Watch this area to determine whether this is a one-time or longer-term problem
  • Create buffers/berms before stormwater is discharged. Tarp/cover wood ash. Address any off-site tracking of ash/wood waste. Sweeping/general good housekeeping.

Sector E, Concrete Manufacturing


  • Dust suppression/management
  • Product/cutting management
  • Slurry management
  • If you cut it the concrete, manage the spray wastewater appropriately (contaminated wastewater cannot be discharged to surface or ground waters)

EPA offers sector-specific fact sheets with BMP options. PDF DocumentSector E’s fact sheetExit to Web highlights:

  • In general, incorporate better housekeeping techniques - Truck wheel contribution to offsite loss?  Dry pond characteristics – may be able to tweak operations by deepening or increasing outlet.   Dry ponds generally don’t treat particulates very well – easier to re-suspend.   
  • Sketch on aerial photos to help identify key site operations, truck traffic and bulk handling areas, covered piles, washout zones, etc.
  • Move monitoring location, slope the land, or divert stormwater to an area where small structural BMPs can be installed. Monitor before stormwater moves into a culvert if the concern is that the culvert is leading to the higher TSS. Make pond/sedimentation system (2-celled system).

Sector L: Landfills


  • PDF Document EPA Sector L Guidance:Exit to Web  See the section dedicated to runoff/erosion issues, as well as “uncontrolled leachate.” 
  • Consider hydrodynamic separators, these can be expensive and require changing filters often (likely not worth the money)
  • Make sure that spray sites have the required buffer area (50-200ft) around the facility. This allows containment of the liquid sprayed.
  • Don’t overspray treated leachate.
  • Stay within the property boundary
  • Don’t allow leachate to run off from the spray field
  • Spray only enough liquid that the cover crop and soil can handle.

Sector L: Landfills


Sector L: Landfills


Sector M: Auto Salvage Yards


  • PDF Document EPA Auto Salvage Exit to Web (specifically the “heavy metals” references)
  • Presuming the parking lots are paved, utilizing a street sweeper for the parking lot areas may help. Of the two generic types of street sweepers; one pushes debris away, and the other has some sort of filter (that can capture and filter out pollutants). 
  • The MPCA PDF Document Vehicle dismantling and salvage (w-hw4-63)
  • The manual provides some BMP ideas to manage industrial activities related to failing parking lots, such as car hulls/parts storage, crushing and/or, sand-blasting activities, or other industry-specific reasons. 
  • The Wisconsin DNR guidance suggests that to control high levels of iron and aluminum, solutions might include proprietary filters, bioretention, and sand filters. A large BMP, such as a wet pond, might need the addition of a polymer to attain a high level of iron control.
  • Washington state guidance includes a PDF Document Metal/Vehicle Recyclers Manual.Exit to Web See page 24 for general BMPs, pages 29-31 for BMPs for crushing areas, part storing areas, and page 32 offers information about contaminated soils.
  • Other contacts include Dave Kendziorski with StormTech, 414-549-1578, or Peter Hughes with the USGS at 608-821-3833.

Sector AA


  • Look at the suggestions for the Sector M: Auto Salvage Yard sector.

Sector AB

Solids, Total Suspended

  • Look at the general suggestions for all sectors above, including those for “gravel parking lot.”

Step 12f:

The following additional resources may help provide information on different BMPs for your facility:


Helpful aspect of resource

EPA Industry Sector Notebooks

Most Industrial Stormwater Sectors are listed; each notebook provides detailed information about processes, pollution prevention opportunities, and more.

State Stormwater BMP Manuals (EPA, 2009)

State-by-state listing of BMP manuals, guidance documents and fact sheets.

Stormwater Best Management Practices in an Ultra-Urban Setting: Selection and Monitoring (US Department of Transportation)

Many structural BMP ideas with diagrams, pollutant removal rates and design and cost considerations.

Commercial/Industrial/Manufacturing BMPs by type of Activity  (Municipal Research and Services Center of Washington, 2009)

Fact sheet series containing BMP ideas for specific types of activities/sectors. 

Portland Industrial Stormwater Best Management Practices

Fact sheet series for more than a dozen specific industrial activities.

University of Minnesota Extension Service Stormwater Education Program

Information about training, manuals, and links to related water-quality programs. 

Step 12g: Contact the MPCA for assistance

If you have reviewed Steps 12a-12f and still need guidance on types of BMPs to implement, you may contact the Program, which can provide you facility-specific suggestions. Contact Melissa Wenzel.

Go to Step 13

Last modified on November 03, 2014 08:37