PART V. BENCHMARK MONITORING REQUIREMENTS

A. The Permittee shall monitor each benchmark monitoring location for all benchmark parameters specified for the facility’s primary SIC code and/or narrative activity and any co-located industrial activity as outlined in Part VII, unless exempted by Part V.B.6.

An exceedance of an applicable benchmark value does not constitute a violation under this permit. However, the Permittee is required to perform any necessary corrective action(s) to address stormwater control measures, including the maintenance or implementation of BMPs, when an exceedance of an applicable benchmark value occurs. Failure to respond to benchmark value exceedances is a violation of the permit.

B. Monitoring for benchmark parameters at each benchmark monitoring location shall be conducted according to the procedures of Part V.B.1, and shall begin 12 months after the date the Permittee is authorized to discharge industrial stormwater under this permit.

1. Monitoring Procedures And Sample Collection Methods

a. 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.

b. The Permittee shall ensure that a laboratory certified by the Minnesota Department of Health conducts analyses required by this permit. If the Permittee is required under this permit to conduct a visual observation sufficient to determine the presence of debris that will not pass through a 2.54 cm (1 inch) round opening, the Permittee is not required to use a laboratory certified by the Minnesota Department of Health for this analysis. Analyses of dissolved oxygen, pH, temperature and total residual oxidants (chlorine, bromine) are not required to be completed by a certified laboratory, but shall comply with manufacturer’s specifications for equipment calibration and use. (Minn. Stat. Sec. 144.97 through 144.98 and Minn. R. 4740.2010 and 4740.2050 through 4740.2120)

c. Four (4) samples shall be collected at each benchmark monitoring location and analyzed for each benchmark parameter specified for the Permittee’s industrial sector(s) in order to determine an average concentration for each benchmark parameter for facility discharges. The four (4) samples shall be collected on four (4) separate events (one per 3-month interval) during the year. At the Permittee’s discretion, more than four (4) samples may be taken during separate runoff events and used to determine the average benchmark parameter concentration for facility discharges. The benchmark parameters are listed in tables in the sector-specific sections of Part VII.

d. For averaging purposes, the Permittee shall use a value of zero for any individual sample parameter that is determined to be less than the method detection limit. For sample values that fall between the method detection level and the quantitation limit (i.e. a confirmed detection, but below the level that can be reliably quantified), the Permittee shall use a value halfway between zero and the quantitation limit.

e. Sampling intervals correspond to 3-month periods beginning 12 months after the date the facility is authorized by the Agency to discharge industrial stormwater under this permit. Samples shall be collected in each of the four (4) intervals of a sampling year and shall be collected during the first 30 minutes of a measurable runoff event at a benchmark monitoring location within a sampling interval to the extent feasible. For every interval the Permittee is required to conduct sampling, a Stormwater Monitoring Report shall be submitted to the Agency in accordance with Part V.B.5 (even if measurable runoff during a sampling interval is not sufficient to obtain a sample).

1. In the absence of a measurable runoff event during a sampling interval due to weather conditions and/or site soil characteristics, the Permittee shall collect a substitute sample during the next sampling interval. This may result in the Permittee collecting more than one sample during an interval. In this case, samples may be taken at any time during an interval, except that sampling events shall be at least 72 hours apart.

2. If the Permittee is unable to obtain a minimum of four (4) samples throughout a sampling year, less than four (4) samples may be used to determine the average benchmark parameter concentration(s) for the discharges during the year. However, for each interval that samples cannot be obtained, the Permittee shall complete the appropriate sections of a Stormwater Monitoring Report, and submit it to the Agency.

3. If the Permittee is unable to obtain at least one sample during second year monitoring as required by Part V.B.2, the Permittee shall conduct fourth year monitoring as required by Part V.B.3.

f. If more than four (4) samples are taken at a benchmark monitoring location during a sampling year, all samples taken shall be reported and used to determine the average benchmark parameter concentration, and the data shall be included in the Stormwater Monitoring Report submitted to the Agency.

g. Samples shall be collected from a measurable runoff event (precipitation or snow melt) at a benchmark monitoring location, provided that the interval since the preceding measurable runoff event is at least 72 hours.

h. If it is not possible to collect the sample within the first 30 minutes of a measurable runoff event at the benchmark monitoring location, the sample shall be collected as soon as practicable after the first 30 minutes and documentation must be included with the Stormwater Monitoring Report that explains why it was not possible to collect samples within the first 30 minutes of a measurable runoff event.

i. Samples shall either be taken manually by grab method, or by automated sampling. If automated sampling is used, the device shall either collect one sample during the first 30 minutes of discharge or a series of samples collected throughout the discharge period, combined as a composite sample.

2. Second Year Monitoring

Unless the Permittee meets the waiver conditions of Part V.B.6, the Permittee shall begin monitoring benchmark parameters specified for the Permittee’s industrial sector(s) using the procedures outlined in Part V.B.1. The second year monitoring interval shall begin no later than twelve (12) months after the date the Permittee is authorized to discharge industrial stormwater under this permit. The Permittee shall collect samples from each stormwater benchmark monitoring location(s) identified by the Permittee in the SWPPP.

Once the second year samples for each benchmark monitoring location(s) have been collected and analyzed, the Permittee shall compare the average of the second year monitoring results with the applicable benchmark value(s) and refer to the following outcomes to determine what further action may be required.

a. Benchmark Values Are Not Exceeded

Further monitoring for those pollutants is not required, unless during subsequent years of permit authorization, a new impaired water has been listed, and the facility has a monitoring location from which the discharge flows to, and is within one mile of, the impaired water. In this case, the Permittee shall:

1. Complete additional monitoring for the benchmark parameter(s) for which the recently listed water is impaired. This only applies if the pollutant(s) of impairment or its appropriate surrogate(s) (Table 2) is among the list of benchmark parameters specified for the Permittee’s industrial sector(s).

ISW appropriate surrogates.
Link to this table

Pollutant of Impairment Surrogate
Biota (Fish)/td> Solids, Total Suspended (TSS)
Biota (Macroinvertabrates) Solids, Total Suspended (TSS)
Biota (Plant) Solids, Total Suspended (TSS)
Dissolved Oxygen (DO) 1BOD, Carbonaceous 05 Day (20 Deg C) (CBOD5), and/or COD (Chemical Oxygen Demand)
Nutrient Eutrophication Biological Indicators Phosphorus, Total (as P)
Turbidity

Solids, Total Suspended (TSS)

1In the case of water impaired for Dissolved Oxygen, the Permittee must monitor for either CBOD5 or COD, or both, depending if these pollutants are among the sector-specific pollutants of the Permittee’s sector in Part VII.


2. No later than 180 days following the USEPA-approved listing of the impaired water, begin the additional monitoring for the pollutant(s) of impairment or its appropriate surrogate(s), using the procedures outlined in Part V.B.1.

3. At the completion of monitoring, follow Part V.B.2.a or Part V.B.2.b.2, which-ever applies.

b. Benchmark Values Are Exceeded

1. If the facility does not have a monitoring location from which a discharge flows to, and is within one mile of, an impaired water or a water listed in Appendix A, Parts B, C, or D, the Permittee shall:

a. Modify the SWPPP and document all corrective actions, including improvements to BMPs, necessary to meet the applicable benchmark values during fourth year monitoring. The Permittee shall include any changes in BMPs and the timeframe for implementation of all corrective actions. Modifications and upgrades of the SWPPP and BMPs shall be completed and implemented no later than 36 months after the Permittee’s authorization to discharge stormwater under this permit.

b. Comply with the monitoring requirements of Part V.B.3 (Fourth Year Monitoring).

2. If the facility has a monitoring location from which a discharge flows to, and is within one mile of, an impaired water listed as impaired for a pollutant(s) of impairment or its appropriate surrogate(s) (Table 2), or a water listed in Appendix A, Parts B, C, or D, the Permittee shall:

a. Modify the SWPPP and document all corrective actions, including improvements to BMPs, necessary to meet the applicable benchmark values during fourth year monitoring. The Permittee shall include any changes in BMPs and the timeframe for implementation of all corrective actions. Modifications and upgrades of the SWPPP shall be completed no later than 30 days past the discovery of the exceedance.

b. Implement necessary non-structural BMPs no later than 60 days after discovery of the exceedance.

c. Implement structural BMPs no later than 180 days after discovery of the exceedance. If the Permittee is unable to complete implementation of structural BMPs within 180 days, the Permittee shall 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 and shall be submitted to the address in Part V.B.5.b of the permit.

d. Comply with the monitoring requirements of Part V.B.3 (Fourth Year Monitoring).

3. Fourth Year Monitoring (If Applicable)

If sampling conducted in accordance with second year monitoring as required in Part V.B.2 resulted in a benchmark value exceedance, the Permittee shall conduct fourth year monitoring, unless the Permittee meets the waiver conditions of Part V.B.6.

The fourth year monitoring interval shall begin no later than thirty-six (36) months after the date the Permittee is authorized to discharge industrial stormwater under this permit. Fourth year monitoring shall be conducted using the procedures outlined in Part V.B.1, and may be limited to only the benchmark parameter(s), and benchmark monitoring locations for which benchmark value(s) were exceeded during the second year monitoring.

Once the fourth year samples for each benchmark monitoring location(s) have been collected and analyzed, the Permittee shall compare the average of the fourth year monitoring results with the applicable benchmark value and refer to the following outcomes to determine what further action may be required.

a. Benchmark Values Are Not Exceeded

Further monitoring for those pollutants is not required, unless during subsequent years of permit authorization, a new impaired water has been listed, and the facility has a monitoring location from which the discharge flows to, and is within one mile of, the impaired water. In this case, the Permittee shall:

1. Complete additional monitoring for the benchmark parameter(s) for which the recently listed water is impaired. This only applies if the pollutant(s) of impairment or its appropriate surrogate(s) (Table 2) is among the list of benchmark parameters specified for the Permittee’s industrial sector(s).

2. No later than 180 days following the approved listing of the impaired water, begin the additional monitoring for the pollutant(s) of impairment or its appropriate surrogate(s), using the procedures outlined in Part V.B.1.

3. At the completion of monitoring, follow Part V.B.3.a or Part V.B.3.b, whichever applies.

b. Benchmark Values Are Exceeded

If the average concentration of any benchmark parameter exceeds a benchmark value specified in Part VII at the completion of the fourth year monitoring, the Permittee shall:

1. Modify the SWPPP and document all corrective actions, including improvements to BMPs, necessary to meet the applicable benchmark values during fifth year monitoring. The Permittee shall include any changes in BMPs and the timeframe for implementation of all corrective actions. Modifications and upgrades of the SWPPP shall be completed no later than 30 days past the discovery of the exceedance.

2. Implement necessary non-structural BMPs no later than 60 days after discovery of the exceedance.

3. Implement structural BMPs no later than 180 days after discovery of the exceedance. If the Permittee is unable to complete implementation of structural BMPs within 180 days, the Permittee shall 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 and shall be submitted to the address in Part V.B.5.b of the permit.

4. Submit a Benchmark Exceedance Report to the address listed in Part V.B.5.b, which describes the inability to meet the benchmark values. The report shall describe in detail the technical basis and reasons why the benchmark values cannot be met. The Benchmark Exceedance Report shall be submitted to the Agency no later than 30 days after the fourth sampling interval of the monitoring year.

5. Comply with the monitoring requirements of Part V.B.4 (Fifth Year Monitoring).

4. Fifth Year Monitoring (If Applicable)

If sampling conducted in accordance with fourth year monitoring as required in Part V.B.3 resulted in a benchmark value exceedance, the Permittee shall conduct fifth year monitoring, unless the Permittee meets the waiver conditions of Part V.B.6.

The fifth year monitoring interval shall begin no later than forty-eight (48) months after the date the Permittee is authorized to discharge industrial stormwater under this permit. Fifth year monitoring shall be conducted using the procedures outlined in Part V.B.1, and may be limited to only the benchmark parameter(s), and benchmark monitoring locations for which a benchmark value was exceeded during the fourth year monitoring.

Once the fifth year samples for each benchmark monitoring location(s) have been collected and analyzed, the Permittee shall compare the average of the fifth year monitoring results with the applicable benchmark value and refer to the following outcomes to determine what further action may be required.

a. Benchmark Values Are Not Exceeded

Further monitoring for those pollutants is not required, unless during subsequent years of permit authorization, a new impaired water has been listed, and the facility has a monitoring location from which the discharge flows to, and is within one mile of, the impaired water. In this case, the Permittee shall:

1. Complete additional monitoring for the benchmark parameter(s) for which the recently listed water is impaired. This only applies if the pollutant(s) of impairment or its appropriate surrogate(s) (Table 2) is among the list of benchmark parameters specified for the Permittee’s industrial sector(s).

2. No later than 180 days following the approved listing of the impaired water, begin the additional monitoring for the pollutant(s) of impairment or its appropriate surrogate(s), using the procedures outlined in Part V.B.1.

3. At the completion of monitoring, follow Part V.B.4.a or Part V.B.4.b, whichever applies.

b. Benchmark Values Are Exceeded

If the average concentration of any benchmark parameter(s) exceeds a benchmark value specified in Part VII at the completion of the fifth year monitoring, the Permittee shall:

1. Modify the SWPPP and document all corrective actions, including improvements to BMPs, necessary to meet the applicable benchmark values during subsequent monitoring. The Permittee shall include any changes in BMPs and the timeframe for implementation of all corrective actions. Modifications and upgrades of the SWPPP shall be completed no later than 30 days past the discovery of the exceedance.

2. Implement necessary non-structural BMPs no later than 60 days after discovery of the exceedance.

3. Implement structural BMPs no later than 180 days after discovery of the exceedance. If the Permittee is unable to complete implementation of structural BMPs within 180 days, the Permittee shall 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 and shall be submitted to the address in Part V.B.5.b of the permit.

4. Submit a Benchmark Exceedance Report to the address listed in Part V.B.5.b, which describes the inability to meet the benchmark values. The report shall describe in detail the technical basis and reasons why the benchmark values cannot be met. The Benchmark Exceedance Report shall be submitted to the Agency no later than 30 days after the fourth sampling interval of the monitoring year.

5. Continue benchmark monitoring of the benchmark parameter(s) exceeded during year 5. The benchmark monitoring interval shall begin 60 months after the Permittee’s authorization to discharge stormwater under this permit and the Permittee shall conduct the repeat benchmark monitoring using the same procedures as outlined in Part V.B.4 (Fifth Year Monitoring).

5. Benchmark Monitoring Data Reporting

a. The Permittee shall submit the results of benchmark monitoring required by this permit on a Stormwater Monitoring Report form provided by the Agency. The information must be recorded in the specified areas on the form and in the units specified (Minn. R. 7001.1090, subp. 1(D), Minn. R. 7001.0150, subp. 2(B)).

If during the sampling period, measurable runoff is such that a sample cannot be acquired (due to weather conditions and/or site soil characteristics), the Permittee shall check the "No Flow" box and note the conditions on the Stormwater Monitoring Report.

b. The Permittee shall submit the Stormwater Monitoring Report form to the Agency postmarked by the 21st day of the month following the sampling interval. The Permittee may submit the form using the electronic submittal process or by mailing the form to the following address:

MPCA

Attn: WQ Submittals Center

520 Lafayette Road North

St. Paul, MN 55155-4194.

c. The Permittee shall immediately submit an amended Stormwater Monitoring Report to the Agency upon discovery by the Permittee or notification by the Agency that the Permittee has submitted an incomplete or incorrect report. The amended report shall contain the missing or corrected data along with a cover letter explaining the circumstances of the incomplete or incorrect report. (Minn. R. 7001.0150, subp. 3(G)).

6. Benchmark Monitoring Waivers

a. General Benchmark Monitoring Waiver

Unless precluded by Part VII of the permit, the Permittee is not required to conduct benchmark monitoring in accordance with Part V of this permit if the Permittee documents in the facility’s SWPPP, and the appropriate sections of a Stormwater Monitoring Report submitted to the Agency (a Stormwater Monitoring Report may be submitted at any time for this purpose), that one or more of the following options is being met at the facility or a portion of the facility.

1. Infiltration BMPs have been designed, constructed, and operated in accordance with Appendix C.

2. Pond BMPs have been designed, constructed, and operated in accordance with Appendix C.

b. Run-On Demonstration Waiver

If the average concentration of any benchmark parameter(s) sampled over the course of a sampling year shows that an applicable benchmark value has been exceeded at a specific benchmark monitoring location, and the Permittee believes that drainage onto the site from up-gradient sources (run-on) may have significantly contributed to or caused the benchmark value exceedance, the Permittee can discontinue monitoring for that pollutant parameter if terms and conditions of this part are met. To qualify for this waiver, the Permittee shall demonstrate that the average of all samples taken of a specific pollutant parameter of the run-on is significantly contributing to, and causing, the pollutant parameter exceedance at the benchmark monitoring location. At a minimum, the Permittee must conduct the following activities to complete the demonstration:

1. Sample the run-on prior to co-mingling with other stormwater discharges, and analyze the run-on against the pollutant parameter for which the benchmark value was exceeded.

2. Include with the SWPPP a run-on demonstration narrative that describes the following:

a. Nature of the run-on including a description of the adjacent property, land use type, and the activity believed to be responsible for the stormwater contamination.

b. The dates and lab results of the samples taken for comparison purposes of the facility benchmark monitoring locations and the sampling points selected for run-on sampling.

c. A statement that the Permittee has assessed and is reasonably assured the run-on flows to, and is directly affecting or related to, the specific benchmark monitoring location for which a benchmark value has been exceeded.

d. Any efforts taken by the Permittee to divert or otherwise minimize run-on to the facility.

e. Any other relevant information that supports the Permittee’s use of this waiver.

3. Complete the appropriate sections of a Stormwater Monitoring Report and submit it to the Agency (a Stormwater Monitoring Report may be submitted at any time for this purpose).

4. Address the use of this waiver in all subsequent Annual Report submittals to the Agency.

c. Natural Background Pollutant Waiver

If during the course of benchmark monitoring the average concentration of a benchmark parameter exceeds a benchmark value, and the Permittee demonstrates to the Agency that the exceedance of the benchmark value is attributable to the presence of that pollutant in the natural background (pollutants from former site operations or run-on are not natural background), the Permittee is not required to perform corrective actions or additional benchmark monitoring of that benchmark parameter provided that:

1. The Permittee demonstrates that the average of all samples taken of a specific benchmark parameter of the natural background is significantly contributing to, and causing, the benchmark value exceedance at the benchmark monitoring location.

2. The Permittee documents and maintains with the SWPPP the supporting rationale for concluding the benchmark value exceedance(s) are attributable to natural background pollutant levels. The Permittee shall include with the supporting rationale any previously collected data that describes the levels of natural background pollutants in the industrial facility stormwater discharge.

3. The Permittee submits notification to the Agency by completing the appropriate sections of a Stormwater Monitoring Report (a Stormwater Monitoring Report may be submitted at any time for this purpose) that the benchmark value exceedance(s) are attributable to natural background pollutant levels. In addition, the Permittee shall address the use of this waiver in all subsequent Annual Report submittals to the Agency.

This page was last edited on 3 April 2013, at 19:39.