Industrial Stormwater Monitoring in Minnesota - Benchmark Monitoring

The Minnesota Pollution Control Agency has released its revised general permit for stormwater discharges from industrial sites. The most important change in the draft permit compared to the previous MPCA general permit is the requirement to sample stormwater discharges.

Flowchart of MPCA Stormwater Monitoring Requirements


All permittees, regardless of size or business sector, will collect and analyze at least four quarterly samples during Year 2 of permit coverage. These samples will be compared to “benchmark” concentrations. Depending on the results, further quarterly samples may need to be collected in Year 4 and 5, and corrective actions may be required. Additional reporting, including a “Benchmark Exceedence Report” and evaluations will be required for dischargers who continue to exceed benchmark concentrations. All sample results will be reported to MPCA.

Related Links:

Further information on stormwater benchmarks

Further information on selecting stormwater monitoring techniques

Comparison of stormwater benchmarks to typical discharge data

It should be noted that some permittees will also be subject to EFFLUENT LIMITS and will have to conduct effluent limit monitoring. The schedule and requirements for effluent limit monitoring are different from Benchmark Monitoring.

Caltha LLP provides expert consulting services to public and private sector clients in Minnesota to address Stormwater Permitting & Regulatory Support, Stormwater Pollution Prevention Plans (SWPPP), Stormwater Monitoring and Stormwater Training.

For further information contact Caltha LLP at
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Virginia DEQ Industrial SWPPP Template - Monitoring Plan Template

The Virginia Department of Environmental Quality (VDEQ) has issued its revised Multi-sector Industrial Stormwater Permit, which became effective on July 1, 2009. The reissued permit includes a number of compliance requirements that are new to many Virginia industries, including:

• Increased training requirements


• Increased inspection requirements


• Stormwater benchmark monitoring

[Read more about changes to DEQ benchmark monitoring requirements]

Existing facilities that were previously covered under the VDEQ industrial permit are required to come into compliance with the reissued permit by October 1, 2009. New facilities are required to be in compliance with the industrial permit when they submit their permit application (Notice of Intent, or NOI).

Caltha LLP has recently completed a stormwater pollution prevention plan (SWPPP) template, Compliance Plan template, and Stormwater Monitoring Plan template specifically constructed to meet the requirements of the new VDEQ stormwater permit. For more information on how these templates can reduce the time and cost for permit compliance, contact Caltha LLP by email at Virginia SWPPP Template

Looking for SWPPP Compliance templates for a different State? Click here

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address Stormwater Permitting & Regulatory Support, Stormwater Pollution Prevention Plans (SWPPP), Stormwater Monitoring and Stormwater Training.

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Virginia VDEQ Stormwater Benchmarks - Changes To Sector Requirements

The Virginia Department of Environmental Quality (DEQ) revised general permit for industrial stormwater discharges became effective on July 1, 2009. The revised permit changed the compliance requirements for many industrial sectors that are subject to the industrial storm water regulations.

Existing facilities that were previous covered under the VDEQ industrial permit are required to come into compliance with the reissued permit by October 1, 2009.

The reissued permit amended some of the requirements for benchmark monitoring, including adding some new industrial sectors that in the past had not been required to conduct benchmark (chemical) monitoring of their stormwater discharges. The amended permit also added to the number of chemical parameters some sectors need to sample for.

Newly Added industrial Sectors that require benchmark monitoring

Sector P Land Transportation and Warehousing
Sector U Dairy Products Facilities
Sector R Ship and Boat Building or Repairing Yards

Industrial Sectors with Expanded Benchmark Monitoring Requirements

Sector N - Ship Dismantling, Marine Salvaging and Marine Wrecking Facilities
Sector S - Airports

The revised permit clarified that benchmark monitoring needs be performed at least once during at least the first two, and potentially all monitoring periods, unless the facility qualifies for a waiver. Benchmark monitoring waiver requests will be evaluated by DEQ based upon (1) benchmark monitoring results below the applicable benchmark concentration values; (2) a favorable compliance history (including inspection results); and (3) no outstanding enforcement actions. The benchmark monitoring waivers can be revoked by DEQ for cause. The revised general storm water permit also clarified that for inactive and unstaffed sites must have no industrial materials or activities exposed to storm water to qualify for this waiver

Caltha LLP has recently completed a stormwater pollution prevention plan (SWPPP) template, Stormwater Monitoring Plan template and Compliance Plan template specifically constructed to meet the requirements of the new VDEQ stormwater permit. For more information on how these templates can reduce the time and cost for permit compliance, contact Caltha LLP by email at Virginia SWPPP Template

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address Stormwater Permitting & Regulatory Support, Stormwater Pollution Prevention Plans (SWPPP), Stormwater Monitoring and Stormwater Training.

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Arkansas Multisector Industrial Stormwater Discharge Permit

This article has been updated:

Final Arkansas ADEQ Industrial Stormwater Discharge Permit

****************************************************************

The Arkansas Department of Environmental Quality (ADEQ) has recently released its draft industrial stormwater discharge permit for public review and comment. The revised permit will replace the existing permit.

Some of the key elements of the draft permit include:

Mult-sector requirements. The draft permit now regulates permitees based on INDUSTRIAL SECTOR designations, rather than SIC code alone. The draft incorporates sector specific stormwater monitoring and benchmark requirements; however, no sector specific stormwater controls or SWPPP requirements are included.

Visual Stormwater Inspections (“visual monitoring”). The draft permit requires a minimum of quarterly visual stormwater monitoring events, in addition to chemical (“benchmark”) monitoring. Once per year, outfalls will also need to be examined during dry weather to confirm the elimination of non-stormwater discharges.

Comprehensive Site Compliance Evaluation. Once each year, qualified personnel must conduct a site compliance evaluations. The evaluation must include a visual inspection for evidence of, or the potential for, pollutants entering the drainage system. Measures to reduce pollutant loadings shall be evaluated to determine whether they are adequate and properly implemented, or whether additional control measures are needed. A visual inspection of equipment needed to implement the spill response equipment must also be
made.

Benchmark Monitoring. Twice each year, a sample must be collected at each stormwater outfall and analyzed for four general effluent characteristic parameters, plus any sector-specific monitoring parameters.

[Read more about proposed ADEQ sector specific stormwater benchmark concentrations]

The Arkansas Department of Environmental Quality (ADEQ) has made available the proposed industrial stormwater permit on its website. The permit is open for public comment until May 11, 2009.

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address Stormwater Permitting & Regulatory Support, Stormwater Pollution Prevention Plans (SWPPP), Stormwater Monitoring and Stormwater Training.

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CT DEP Stormwater Target Values, Action Levels and Benchmarks

The Connecticut Department of Environmental Protection (“DEP”) has proposed to revise and renew its General Permit for the Discharge of Stormwater Associated with Industrial Activity. The previous General Permit was adopted in 2002, modified in 2003, and expired on September 30, 2007. It was extended on October 1, 2007 and October 1, 2008 through March 31, 2008 without change by DEP to provide ongoing coverage to approximately 1,500 registrants.

The 2002 permit required annual monitoring of stormwater discharges from qualifying storm events for an expansive list of chemical and physical parameters, including whole effluent toxicity, and a set of Target Values for the parameters based on the 80th percentile of the monitoring data collected in previous years.

In 2008, DEP announced that it would be revising the permit. It proposed to update its 80th percentile Target Values to reflect the monitoring data acquired since the prior permit was adopted in 2002. DER also proposed Action Levels at the 95th percentile of prior monitoring results which would require follow-up action by registrants to investigate the source of the exceedances and modify their BMPs and SWPPP.

On February 4, 2009, DEP issued a new proposed draft which adopts ten sectors modeled on the EPA “MSGP-2008” Multisector permit, with semi-annual monitoring. The previously proposed “Action Levels” have become “Benchmarks” to track the federal language. DEP’s proposal retains the broad spectrum of parameters to be included in the monitoring program, including toxicity, but makes some sector specific adjustments. The toxicity monitoring requirement carries with it no Benchmark. The draft also adds annual monitoring for parameters for which receiving waters have been designated impaired or subject to Total Maximum Daily Load restrictions.

The Benchmark values for copper, lead and zinc are based on Connecticut’s State Water Quality Standards. The Benchmarks for remaining parameters (pH, O&G, COD, TSS, TP, TKN, and NO3), are based on the 50th percentile of the previously acquired monitoring data.

DEP expects to go to notice on a new proposal in April 2009. In the meantime, the DEP has published notice that it intends to extend the 2002 General Permit once again until September 30, 2010.

[Read more about Water Quality Standards, Aquatic Toxicology and NPDES Permit Limits]

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address Stormwater Permitting & Regulatory Support, Stormwater Pollution Prevention Plans (SWPPP), Stormwater Monitoring and Stormwater Training.

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Visual - Benchmark Stormwater Monitoring Compared To Wet Weather Inspections

Overtime, the requirements for stormwater discharge monitoring have shifted. During the 1990s, when stormwater discharge permitting requirements began to develop, “wet weather inspections” were incorporated into many State general permits. These inspections were to be conducted during a rain event and required the discharger to make certain observations about the stormwater being discharged at each of the stormwater outfalls. In most cases, wet weather inspections could be conducted without actually collecting a sample of the stormwater discharge.

Subsequently, the US EPA Multisector General Permit (MSGP) became more detailed and the Visual Monitoring requirement was developed. Overtime, State permits also incorporated a requirement to conduct visual monitoring. However, in some cases permits were not clear as to whether or not a sample of stormwater needed to be collected. Because of this ambiguity, some dischargers believed that the same protocol they were using for wet weather inspections still applied.

Recently, the EPA MSGP was revised to eliminate any uncertainty regarding the protocol to be used for Visual Monitoring:
“The visual assessment must be made:
- Of a sample in a clean, clear glass, or plastic container, and examined in a well-lit area;
- On samples collected within the first 30 minutes of an actual discharge from a storm event.”

Benchmark monitoring is also required of some industrial sectors. Benchmark monitoring becomes an extension of Visual Monitoring. Rather than documenting the visual characteristics of the sample, it is simply sent to an analytical laboratory for chemical analysis.

Therefore, in practice the same basic protocol is required to collect stormwater samples for both visual monitoring and benchmark monitoring.

[Read more about benchmark monitoring]
[Read more about selected stormwater monitoring techniques and equipment]

Caltha LLP provides a range of stormwater monitoring services, from development of a written Stormwater Monitoring Plan, to conducting stormwater monitoring training, to supplying equipment and sampling personnel to collect samples.
[Read more about Stormwater Monitoring Services]

For further information contact Caltha LLP at
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Stormwater Monitoring – Storm Water Sampling Services

An increasing number of States require routine sampling of stormwater discharges to demonstrate compliance with NPDES discharge permits. Whether samples are needed for visual monitoring, chemical monitoring, or benchmark monitoring, one of the more challenging tasks a permitted facility must address is how to collect valid stormwater samples.

Caltha LLP provides expert technical support to permitted facilities and/or their consultants and engineers to develop stormwater monitoring programs developed to meet the requirements of individual States. Storm water programs are provided to meeting the needs of both Industrial and Municipal (MS4) stormwater dischargers.

[Read more about selecting the right stormwater monitoring approach]
[Read more about stormwater benchmark monitoring]

Caltha LLP provides a range of stormwater monitoring services, from development of a written Stormwater Monitoring Plan, to conducting stormwater monitoring training, to supplying equipment and sampling personnel to collect samples.
[Read more about Stormwater Monitoring Services]

Caltha provides State-specific stormwater training for the following States:
[Click on a State to request more information]

Alabama Stormwater Monitoring
Arizona Stormwater Monitoring
Arkansas Stormwater Monitoring
California Stormwater Monitoring
Connecticut Stormwater Monitoring
Florida Stormwater Monitoring
Georgia Stormwater Monitoring
Illinois Stormwater Monitoring
Indiana Stormwater Monitoring
Iowa Stormwater Monitoring
Kansas Stormwater Monitoring
Kentucky Stormwater Monitoring
Louisiana Stormwater Monitoring
Massachusetts Stormwater Monitoring
Michigan Stormwater Monitoring
Minnesota Stormwater Monitoring
Mississippi Stormwater Monitoring
Nebraska Stormwater Monitoring
Nevada Stormwater Monitoring
New Jersey Stormwater Monitoring
New York Stormwater Monitoring
North Carolina Stormwater Monitoring
North Dakota Stormwater Monitoring
Ohio Stormwater Monitoring
Oklahoma Stormwater Monitoring
Oregon Stormwater Monitoring
Pennsylvania Stormwater Monitoring
South Carolina Stormwater Monitoring
South Dakota Stormwater Monitoring
Tennessee Stormwater Monitoring
Texas Stormwater Monitoring
Utah Stormwater Monitoring
Virginia Stormwater Monitoring
Washington Stormwater Monitoring
Wisconsin Stormwater Monitoring

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Substantially Identical Outfalls - Substantially Identical Effluents

One option potentially available to dischargers required to conduct stormwater monitoring is the use of "Substantially Identical" outfalls. This is particularly useful to facilities with many outfalls that need to be monitored.

The selection of substantially identical outfalls does not have to be "pre-approved" in many cases. However, the risk to dischargers is that if the permitting agency does not agree with the determination of substantially identical outfalls, the discharger may be subject to enforcement action. Therefore, careful consideration and documentation that the selected identical outfalls are valid is important.

The criteria used to determine if the "Substantially Identical" option applies will change from State-to-State. Generally, the factors used can include:

• Location ;
• Industrial activities conducted in the drainage area of each outfall;
• Control measures implemented in the drainage area of each outfall;
• Materials used or stored;
• Runoff coefficient of the drainage areas.

Caltha LLP assists dischargers nationwide in developing and implementing cost effective stormwater monitoring programs, including determination and documentation of substantially identical outfalls. To request further information, go to SWPPP and SPCC website.

For further information contact Caltha LLP at
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Substantially Identical Outfalls - Potential Option To Reduce Sampling Costs

One option potentially available to dischargers required to conduct stormwater monitoring is the use of "Substantially Identical" outfalls. This is particularly useful to facilities with many outfalls that need to be monitored.

The availability of this option will change from State-to-State, as will the exact requirements. However, generally if the facility has two or more outfalls that discharge substantially identical effluents, the facility may be allowed to conduct visual and/or benchmark monitoring at one of the outfalls and report that the results also apply to the substantially identical outfall(s). In many cases, the facility will need to perform monitoring on a rotating basis of each substantially identical outfall. However, if stormwater contamination is identified at any substantially identical outfall, control measures may need to be installed for all identical outfalls.

In many cases, selection of substantially identical outfalls does not have to be "pre-approved". However, the risk to dischargers is that if during subsequent compliance inspections the permitting agency does not agree with the determination of substantially identical outfalls, the discharger may be subject to enforcement action. Therefore, careful consideration and documentation that the selected identical outfalls are valid is important.

[Read more about factors used to determine substantially identical outfalls]

Caltha LLP asssists dischargers nationwide in developing and implementing cost effective stormwater monitoring programs, including determination and documentation of substantially identical outfalls. To request further information, go to SWPPP and SPCC website.

For further information contact Caltha LLP at
info@calthacompany.com
or
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Stormwater Monitoring - Considerations for Selecting Sampling Technique

Selecting the optimum stormwater sampling approach is a key element to managing costs for stormwater compliance monitoring.

[read more about three basic approaches to collecting stormwater samples]

Selecting the appropriate option for a given discharger requires consideration of all the outfalls that need to be sampled. For example, some outfalls may not be conducive for installing automated sampling equipment, and might require a different technique. Therefore, if a facility has four outfalls to sample and one can not be effectively sampled with automated equipment, staff may need to be trained to collect samples at that outfall anyway, and therefore it may not make much sense to install automated equipment at the other outfalls, unless other factors prevail.

The bottom line is that selecting a reliable and cost effective sampling method is dependant on a number of factors, including:

• Frequency of monitoring
• Types of parameters to be tested for
• Physical layout and constraints of the outfalls
• Safety considerations
• Availability of on-site staff
• Availability of contract sampling vendors
• Availability of equipment

Caltha LLP assists companies in addressing their requirements under State and Federal stormwater rules. Click here to request further information on Stormwater and SWPPP Services.

For further information contact Caltha LLP at
info@calthacompany.com
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Cost for Stormwater Monitoring - Managing Costs By Selecting Optimum Sampling Stategy

Many States now require dischargers to collect stormwater samples to demonstrate that their stormwater pollution prevention measures are effective. Samples are either visually examined on-site, or sent to a laboratory for chemical analysis. Either way – samples need to be collected.

Because in most States samples need to be collected within the first 30 minutes of discharge, stormwater monitoring presents some special challenges. To further complicate this requirement, rain events may also need meet specific requirements (i.e., 0.25 inch total rain fall, dry for previous 3 days, etc.). There are three basic options available to dischargers:

1. Train Facility Staff to Collect Samples. In this case, a few staff are trained on how to collect and handle samples.
2. Contract Third-party Sampler. Here, you would need to contract with a vendor who is located close enough to be at the site and ready to sample within 30 minutes of the start of a rain fall event.
3. Buy or Lease Automated Sampling Equipment. In this case, equipment is installed at each outfall and samples are collected automatically when water begins to flow. In most cases, equipment would need to be installed by trained personnel.
   

Each of these options has its unique benefits and drawbacks. Using a third-party sampler has some logistically problems, as most facilities find it difficult to have someone on-site within 30 minutes, especially considering that the vendor may also be providing this service to others. Using automatic equipment eliminates this logistical problem; however, automated equipment tends to be more costly, and often needs to be reset after small rain events or if any other water gets inadvertently discharged to the storm sewer. Therefore many dischargers opt to train their own staff to collect samples, as it is the least expensive and most reliable method.

Caltha LLP assists companies in addressing their requirements under State and Federal stormwater rules, including Development of Stormwater Monitoring Plans and Training Facility Staff to Collect Stormwater Samples. Click here to request further information on Stormwater and SWPPP Services.

For further information contact Caltha LLP at
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Hazardous Metals in Stormwater – Texas (TCEQ) Requirements

As general permits for stormwater discharges are revised, States will attempt to address requirements for impaired waters into the permit requirements. How these requirements are expressed in the permit varies widely from State-to-State. Some States have developed requirements which promote pollution prevention measures.

As one example, the State of Texas has detected levels of selected heavy metals in surface waters which are of concern, and has promulgated numeric discharge standards for “hazardous metals” into the industrial stormwater permit. However, the Texas Commission on Environmental Quality (TCEQ) approach is to allow facilities to do a self-assessment for sources of hazardous metals and implement pollution prevention measures to avoid the higher costs of hazardous metal sampling and testing. To be exempted, facilities must certify that:

• Facility does not use a raw material, produce an intermediate product, or produce a final product that contains one of the listed hazardous metals, or


• Any raw materials, intermediate products, or final products which contain a hazardous metal are never exposed to stormwater or runoff, or


• Facility collects and analyses stormwater samples from the facility and the results indicate that hazardous metal(s) are not present in detectable levels.
  

Waivers may be obtained on a metal-by-metal basis, or on an outfall-by-outfall basis. A waiver from hazardous metals monitoring does not exempt the facility from other benchmark monitoring requirements which may apply. [Read more about benchmark monitoring]

Caltha LLP provides support to facilities nationwide on meeting State stormwater permit requirements and developing effective stormwater pollution prevention programs, including SWPPP training and stormwater compliance training programs.

For further information contact Caltha LLP at
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EPA Proposed Stormwater Eflluent Limits - Comparison To Benchmark Concentration

In December 2008, US EPA published proposed effluent limits for stormwater discharges from construction sites. [Read more about proposed limits] The proposed rules included a numeric effluent limit of 90 NTU. NTUs are a standard measurement of turbidity in water. Turbidity is a measurement of suspended material in the water.

Benchmark values and previous stormwater effluent limits have always been expressed as Total Suspended Solids (TSS). Turbidity is related to TSS, however the relationship between turbidity and TSS is not always direct, and will be affected by a number of different factors.

Stormwater benchmark concentrations for TSS usually range from 100 to 250 mg/L. Using a few typical conversions between NTU and TSS, it is predicted that an effluent limit of 90 NTU will be roughly equivalent to 45 to 65 mg/L expressed as TSS. Therefore, it is projected that the proposed stormwater effluent limit is about one-half the lowest current benchmark concentration for TSS.

Caltha LLP provides expert technical support to dischargers subject to State and EPA stormwater discharge permit, including permitting, SWPPP training, stormwater monitoring, site inspections, and overall compliance program development.

For further information contact Caltha LLP at
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Using Infiltration as Stormwater BMP - Regulatory Issues

Infiltration is used as a stormwater control or Best Management Practice (BMP) in many areas. However, infiltrating run-off has some unique regulatory issues. First, in some States, infiltrating stormwater is a viable means to eliminate a discharge that would otherwise require an NPDES discharge permit. However, in most cases, the system would need to infiltrate all run-off from even the largest rain events. In addition, seasonal changes must also be considered; all run-off would need be collected and infiltrated even during frozen conditions. Some States, such as Minnesota, regulate groundwater as a "water of the State", and therefore can regulate discharges to the groundwater using infiltration.

The Minnesota Pollution Control Agency (MPCA) has been drafting regulations relating to infiltration of stormwater at sites regulated under the industrial stormwater discharge general permit. These requirements are still in revision, however as of November 2008 the format for regulation of infiltration as a stormwater control has included:

• Design criteria for amount of run-off to be infiltrated
• Rate at which infiltration must occur after a storm event
• Pretreatment requirements for run-off prior to discharge to designed infiltration basin
• Stormwater monitoring requirements and standards ("benchmarks") for run-off prior to discharge to designed infiltration basin
• Operation and maintenance requirements.

The draft MPCA infiltration requirements also include several prohibitions, where infiltration can not be used to manage stormwater. These include:

• Certain industrial sectors are prohibited from using infiltration BMPs;
• Certain sensitive areas where groundwater is vulnerable to contamination, including karst areas, and well head protection areas.

Finally, under some circumstances the disposal of stormwater run-off using a designed infiltration system can be further regulated as a Class V Injection Well. This will require further permitting and associated regulation.

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MPCA Stormwater Monitoring Requirements - Proposed Requirements

The Minnesota Pollution Control Agency has released its revised general permit for stormwater discharges from industrial sites. The current general permit was written in 1997, and the upcoming revision will reflect major changes in stormwater permitting requirements.

Review a summary of the MPCA industrial permit

The most important proposed change in the draft permit compared to the current MPCA general permit is the requirement to sample stormwater discharges.

Flowchart of Draft MPCA Stormwater Monitoring Requirements


All permittees will collect and analyze at least four quarterly samples during Year 2 of permit coverage. These samples will be compared to “benchmark” concentrations. Depending on the results, further quarterly samples may need to be collected in Year 4 and 5, and corrective actions may be required. Additional reporting, including a “Benchmark Exceedence Report” and evaluations will be required for dischargers who continue to exceed benchmark concentrations. All sample results will be reported to MPCA.

Related Links:

Further information on stormwater benchmarks

Further information on selecting stormwater monitoring techniques

Comparison of stormwater benchmarks to typical discharge data

For further information contact Caltha LLP at
info@calthacompany.com
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Caltha LLP Website

MPCA Industrial Stormwater - Key Elements of Draft Permit

UPDATE: On July 6, 2009, MPCA is scheduled to release its proposed Multisector Industrial General Stormwater Permit. In July, Caltha LLP will be hosting seminars in several cities across Minnesota to provide information on the proposed permit and rule changes, and steps facilities can take to reduce their impact.

For more information, go to:

MPCA SWPPP Permit - Industrial Stormwater Permit Reissue Seminars

++++++++++++++++++++++++++

The Minnesota Pollution Control Agency has been drafting its revised general permit for stormwater discharges from industrial sites. The current general permit was written in 1997, and the upcoming revision will reflect major changes in stormwater permitting requirements.

A partial draft permit was released on November 20, 2008. This draft did not contain some important sections of the permit – most significantly, it did not include any SECTOR SPECIFIC requirements which will be incorporated into the final permit. All sections of the draft are subject to further revision; this article provides a briefing on some of the key elements of the draft permit.

Some key requirements in the draft permit are:

Requirements for Designated “Special” Waters. MPCA intends to have additional requirements for stormwater discharges to a number of different types of special waters, such as trout streams, wetlands and others. The nature of these additional requirements has not been released.

Facility Inspections. Facility inspections will need to be conducted on a monthly basis. All employee(s) performing inspections must be trained.

Maintenance of BMPs. If BMPs/structural controls are found to be not functioning properly, repairs should be made within seven days. Anyone performing installation, inspection, maintenance and repair of BMPs must have appropriate training.

Mercury Minimization Plan. Each permittee must evaluate their facility to determine if any sources of mercury are potentially exposed to stormwater. If mercury sources or devices are found, a Mercury Minimization Plan must be developed.

Stormwater Monitoring. The most important change compared to the current MPCA general permit is the requirement to sample stormwater discharges. All permittees will collect and analyze at least four quarterly samples during Year 2 of permit coverage. Depending on the results, further samples may need to be collected in Year 4 and 5, and corrective actions may be required. Additional reporting and evaluations will be required for dischargers who continue to exceed benchmark concentrations.

Related Links:
Flowchart of Draft MPCA Stormwater Monitoring Requirements
Further information on stormwater benchmarks
Comparison of stormwater benchmarks to typical discharge data
Further information on selecting stormwater monitoring techniques

Special Requirements for Stormwater Infiltration. MPCA intends to include specific requirements for the design and operation of infiltration BMPs. For some industry sectors, infiltration will be prohibited.

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Stormwater Benchmarks - Comparison To Typical Stormwater Concentrations

About one-third of US States include chemical monitoring in their general stormwater discharges permits. Over time, this percentage has been increasing as States renew these permits as they expire. For States that require chemical analysis of stormwater samples, “benchmark” concentrations or values are often included. Benchmark concentrations can be specified for a number of different chemical parameters, but the more common chemicals which are assigned benchmarks include total suspended solids (TSS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nutrients and heavy metals.

Benchmark values differ from permit limits. In a typical wastewater NPDES permit, limits may be specified for chemical parameters; if any of the limits are exceeded, it becomes a violation of the permit and may be subject to enforcement action.

Benchmark values are intended to provide a measurement of the effectiveness of the stormwater pollution prevention plan (SWPPP). Exceeding a benchmark does not directly result in a permit violation. However, permits typically require facilities to reevaluate their SWPPP and to take prompt corrective action after a benchmark value is exceeded. Failure to take prompt corrective action if a benchmark value is exceeded can be a permit violation and subject to enforcement action.

Benchmark values tend to be fairly stringent. For example, a common benchmark concentration for total suspended solids (TSS) is 100 mg/L. To put this concentration into perspective, it is roughly equivalent to 1 teaspoon of sediment added to 14.5 gallons of water.

As a sector example, US EPA tested the stormwater discharge at 185 transportation and warehousing facilities. The average TSS was reported as 466 mg/L and half the facilities sampled exceeded 159 mg/L (Federal Register Vol. 60, No. 189).

The message in these data is simple; meeting stormwater benchmark values or other stormwater discharge limits can be a challenge to many facilities. It requires a thoughtful evaluation of potential pollution sources and an effective plan to minimize discharges.

[read more about selecting appropriate stormwater monitoring techniques]

Caltha LLP maintains a library of Stormwater Monitoring Plan templates to meet individual State requirements, and provides ad hoc technical guidance in developing and implementing stormwater monitoring programs.

For further information contact Caltha LLP at
info@calthacompany.com
or
Caltha LLP Website

Stormwater Benchmarks Compared to Permit Limits

Benchmark values differ from permit limits. In a typical wastewater NPDES permit, limits may be specified for chemical parameters; if any of the limits are exceeded, it becomes a violation of the permit and may be subject to enforcement action.

Benchmark values are intended to provide a measurement of the effectiveness of the stormwater pollution prevention plan (SWPPP). Exceeding a benchmark does not directly result in a permit violation. However, permits typically require facilities to reevaluate their SWPPP and to take prompt corrective action after a benchmark value is exceeded. Failure to take prompt corrective action if a benchmark value is exceeded can be a permit violation and subject to enforcement action. Multiple exceedances of a benchmark could result in a State requiring that the facility apply for an individual stormwater discharge permit. In this case, legally enforceable stormwater discharge limits may be written into the permit.

[read more about selecting appropriate stormwater monitoring techniques]

Caltha LLP maintains a library of Stormwater Monitoring Plan templates to meet individual State requirements, and can provide ad hoc technical guidance in development of stormwater monitoring programs.

For further information contact Caltha LLP at
info@calthacompany.com
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Caltha LLP Website

Polycyclic Aromatic Hydrocarbons in Stormwater - Austin Sealcoating Studies

Collaborative studies (Fact Sheet) by the City of Austin, TX, and the U. S. Geological Survey have identified coal-tar based sealcoat as a major and previously unrecognized source of polycyclic aromatic hydrocarbon (PAH) contamination. Several PAHs are suspected human carcinogens and are toxic to aquatic life. Studies in Austin, Texas, showed that particles in runoff from coal-tar based sealcoated parking lots have concentrations of PAHs that are about 65 times higher than concentrations in particles washed off parking lots that have not been sealcoated. Biological studies, conducted by the City of Austin in the field and in the laboratory, indicate that PAH levels in sediment contaminated with abraded sealcoat are toxic to aquatic life and are degrading aquatic communities, as indicated by loss of species and decreased numbers of organisms.

This research has led the City of Austin to ban the use of coal-tar sealants for roads, parking lots, driveways, and other paved areas.

For further information contact Caltha LLP at
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Stormwater Monitoring - Selecting Appropriate Technique and Equipment

Many States now require dischargers to collect stormwater samples to demonstrate that their stormwater pollution prevention measures are effective. Samples are either visually examined on-site, or sent to a laboratory for chemical analysis. Either way – samples need to be collected.

Because in most States samples need to be collected within the first 30 minutes of discharge, stormwater monitoring presents some special challenges. To further complicate this requirement, rain events may also need meet specific requirements (i.e., 0.25 inch total rain fall, dry for previous 3 days, etc.). There are three basic options available to dischargers:

1. Train Facility Staff to Collect Samples. In this case, a few staff are trained on how to collect and handle samples.
2. Contract Third-party Sampler. Here, you would need to contract with a vendor who is located close enough to be at the site and ready to sample within 30 minutes of the start of a rain fall event.
3. Buy or Lease Automated Sampling Equipment. In this case, equipment is installed at each outfall and samples are collected automatically when water begins to flow. In most cases, equipment would need to be installed by trained personnel.
   

Each of these options has its unique benefits and drawbacks. Using a third-party sampler has some logistically problems, as most facilities find it difficult to have someone on-site within 30 minutes, especially considering that the vendor may also be providing this service to others. Using automatic equipment eliminates this logistical problem; however, automated equipment tends to be more costly, and often needs to be reset after small rain events or if any other water gets inadvertently discharged to the storm sewer. Therefore many dischargers opt to train their own staff to collect samples, as it is the least expensive and most reliable method.

Selecting the appropriate option for a given discharger requires consideration of all the outfalls that need to be sampled. For example, some outfalls may not be conducive for installing automated sampling equipment, and might require a different technique. Therefore, if a facility has four outfalls to sample and one can not be effectively sampled with automated equipment, staff may need to be trained to collect samples at that outfall anyway, and therefore it may not make much sense to install automated equipment at the other outfalls, unless other factors prevail.

The bottom line is that selecting a reliable and cost effective sampling method is dependant on a number of factors, including:

• Frequency of monitoring
• Types of parameters to be tested for
• Physical layout and constraints of the outfalls
• Safety considerations
• Availability of on-site staff
• Availability of contract sampling vendors
• Availability of equipment

For further information contact Caltha LLP at
info@calthacompany.com
or
Caltha LLP Website

Stormwater Permit and SWPPP Requirements - Summary Trends and Changes

Here is a link to a presentation given at the ACHMM Annual Conference in August 2007:

Trends and Changes in Stormwater Permitting and SWPPP Requirements Across US

For further information contact Caltha LLP at
info@calthacompany.com
or
Caltha LLP Website