Response to comments

• Comment: I did not have time read in depth about the BMPs, but I cannot stress enough that the best available information be included in here about protecting ground water, infiltration requirements in DWSMA's, vulnerable areas etc.

Response: This information will be updated in the coming year. See http://stormwater.pca.state.mn.us/index.php/Future_updates#Updates_to_information_on_infiltration_and_infiltration_constraints

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• Comment: Consider having external links open in a new tab if possible. This may be personal preference. -Add link to Ag BMP handbook, I feel some of the research and concepts can be applied to the audience using this manual: http://www.eorinc.com/documents/AG-BMPHandbookforMN_09_2012.pdf

Response: Other webpages can be opened in a new tab by right clicking on the link and selecting "Open in a new tab". The Ag BMP handbook link has been added.

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• Comment: Shouldn't ATLAS 14 be referenced here, rather than TP-40?

Response: This is part of on-going contract work and the Manual will be updated with respect to this issue.

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• Comment: Although the data is lacking, it would be nice to have a 'What we Know' summary of that data and where it came from. (Note: this comment pertains to the page on Stormwater research and education.)

Response:The information on the Stormwater research and education page is from the original Manual. We agree it is in need of updating and will attempt to update this when resources allow.

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• Comment: http://fyi.uwex.edu/shwec/2013/05/29/minnesota-bans-toxic-asphalt-sealcoats/ Please update to include information on the ban of coal tar sealcoat. Thank you!

Response: For now, we've added an alert box informing people that the ban is in effect January 1, 2014. We anticipate additional information being added in August.

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• Comment: Do US EPA WaterSense smart irrigation controllers fall into storm water quantity or quality BMPs for landscape management, and could it be used as a mitigation technique that qualifies for storm water credit in the City of Minneapolis? The controllers monitor plant, soil, and weather data to carefully control calculated daily irrigation schedules, eliminating saturated soils before rain events and minimizing the potential for overland flow generated on vegetated surfaces.

Response: We consulted with Lois Eberhart, City of Minneapolis Water Resources Adminstrator. Her response was:

"No, we would not consider any sort of irrigation management to be eligible for stormwater quality or stormwater quantity credits against the city’s Stormwater Utility Fee. Strictly speaking, irrigation water is non-stormwater and therefore is not intended to enter the MS4 stormwater system, under the city’s MS4 permit (although Minneapolis does not typically seek out, for purposes of enforcement, property owners/managers that are over-irrigating). (The irrigation control would of course save the user money on the water bill due to purchasing less potable water.)"

This is consistent with MPCA's view that irrigation water is non-stormwater and therefore credits should not be given. However, we believe the technology has value and would encourage its use in cases where irrigation is being used.

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• Comment:It is really frustrating when you have to open each section separately. For example, I should have the option to be able to click on the main heading of Stormwater Modeling, etc. and view all six sections at the same time instead of having to click on each of the six sections separately.

Response: We have created an option to view all the articles as a single document. We will likely do the same where appropriate in other places in the Table of Contents. Another option for the Manual user is to create a book (see left toolbar), which allows customization of an article.

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• Comment: Atlas 14 Volume 8 has been completed by NOAA. It is available on the web at http://hdsc.nws.noaa.gov/hdsc/pfds/ This information supercedes TP-40. There are references about using TP-40 throughout this document that should be updated.

Response: We understand the need to update the Manual on this topic and will be doing so in the near future.

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• Comment: If all discharge is sheet flow, it would not be a regulated discharge correct? (My understanding is that it would need to form a channel at the point it left the property or entered waters of the state to be regulated).

Response: As long as the Permittee has chosen their Benchmark Monitoring Location in accordance with the definition of the Industrial Stormwater Permit, how they collect the sample doesn't change that it's a regulated industrial stormwater discharge.

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• Comment: How about replacing these TP 40 maps with Atlas 14 which was has now been adopted by NOAA.

Response We have added a link to Atlas 14. The Stormwater Manual will be updated in the future.

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• Comment: The heading notes that there are two different rates for group B soils, but only one is displayed. The old manual used to have a 0.6 inches per hour rate for group B soils.

Response: As part of the MIDS project, a technical team evaluated the infiltration table and determined there should be one value for B soils (0.3 in/hr). The heading is corrected. This is an important change and we are discussing how to inform Manual users about these types of changes.

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• Comment: This (Stormwater pond/wetland O & M checklist) is a very comprehensive list; most of the criteria would be helpful. It should be reformatted so that it prints more clearly and in a smaller number of pages. A 4 page check list when you are inspecting a pond is too much.

Response: In the header for select checklists we have added an option to access an Excel version of the checklist

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• Comment:The requirement for two year monitoring seems extremely hard on these systems. Monitoring requirements are not stipulated, pre-installation monitoring is required to characterize the runoff etc. No one in their right mind will do this on every site installation. Take into account that field monitoring devices themselves have been shown to be extremely inaccurate. With the move to MID design standards all tools are valid and for urban redevelopment underground systems may be the best option for the site. I strongly recommend replacing the monitoring requirement with a more stringent design process, say sizing on 50 um lab test using a treatment flow rate developed from the design storm event. Then require washout verification to say below 50 mg/l so that retention of sediment is also considered. A lot of work has been done at SAFL on this.

Response:This will not be required under the new CSW permit and it has therefore been removed.

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• Comment: How about replacing these TP 40 maps with Atlas 14 which was has now been adopted by NOAA.

Response We have added a link to Atlas 14. The Stormwater Manual will be updated in the future.

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• Comment: The heading notes that there are two different rates for group B soils, but only one is displayed. The old manual used to have a 0.6 inches per hour rate for group B soils.

Response: As part of the MIDS project, a technical team evaluated the infiltration table and determined there should be one value for B soils (0.3 in/hr). The heading is corrected. This is an important change and we are discussing how to inform Manual users about these types of changes.

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• Comment: This (Stormwater pond/wetland O & M checklist) is a very comprehensive list; most of the criteria would be helpful. It should be reformatted so that it prints more clearly and in a smaller number of pages. A 4 page check list when you are inspecting a pond is too much.

Response: In the header for select checklists we have added an option to access an Excel version of the checklist

—————————————————————————————————————————————————————————————————————

• Comment:The requirement for two year monitoring seems extremely hard on these systems. Monitoring requirements are not stipulated, pre-installation monitoring is required to characterize the runoff etc. No one in their right mind will do this on every site installation. Take into account that field monitoring devices themselves have been shown to be extremely inaccurate. With the move to MID design standards all tools are valid and for urban redevelopment underground systems may be the best option for the site. I strongly recommend replacing the monitoring requirement with a more stringent design process, say sizing on 50 um lab test using a treatment flow rate developed from the design storm event. Then require washout verification to say below 50 mg/l so that retention of sediment is also considered. A lot of work has been done at SAFL on this.

Response:This will not be required under the new CSW permit and it has therefore been removed.

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• Comment: Do US EPA WaterSense smart irrigation controllers fall into storm water quantity or quality BMPs for landscape management, and could it be used as a mitigation technique that qualifies for storm water credit in the City of Minneapolis? The controllers monitor plant, soil, and weather data to carefully control calculated daily irrigation schedules, eliminating saturated soils before rain events and minimizing the potential for overland flow generated on vegetated surfaces.

Response: We consulted with Lois Eberhart, City of Minneapolis Water Resources Adminstrator. Her response was:

"No, we would not consider any sort of irrigation management to be eligible for stormwater quality or stormwater quantity credits against the city’s Stormwater Utility Fee. Strictly speaking, irrigation water is non-stormwater and therefore is not intended to enter the MS4 stormwater system, under the city’s MS4 permit (although Minneapolis does not typically seek out, for purposes of enforcement, property owners/managers that are over-irrigating). (The irrigation control would of course save the user money on the water bill due to purchasing less potable water.)"

This is consistent with MPCA's view that irrigation water is non-stormwater and therefore credits should not be given. However, we believe the technology has value and would encourage its use in cases where irrigation is being used.

—————————————————————————————————————————————————————————————————————

• Comment:It is really frustrating when you have to open each section separately. For example, I should have the option to be able to click on the main heading of Stormwater Modeling, etc. and view all six sections at the same time instead of having to click on each of the six sections separately.

Response: We have created an option to view all the articles as a single document. We will likely do the same where appropriate in other places in the Table of Contents. Another option for the Manual user is to create a book (see left toolbar), which allows customization of an article.

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• Comment: Atlas 14 Volume 8 has been completed by NOAA. It is available on the web at http://hdsc.nws.noaa.gov/hdsc/pfds/ This information supercedes TP-40. There are references about using TP-40 throughout this document that should be updated.

Response: We understand the need to update the Manual on this topic and will be doing so in the near future.

—————————————————————————————————————————————————————————————————————

• Comment: If all discharge is sheet flow, it would not be a regulated discharge correct? (My understanding is that it would need to form a channel at the point it left the property or entered waters of the state to be regulated).

Response: As long as the Permittee has chosen their Benchmark Monitoring Location in accordance with the definition of the Industrial Stormwater Permit, how they collect the sample doesn't change that it's a regulated industrial stormwater discharge.

—————————————————————————————————————————————————————————————————————

• Comment: How about replacing these TP 40 maps with Atlas 14 which was has now been adopted by NOAA.

Response We have added a link to Atlas 14. The Stormwater Manual will be updated in the future.

—————————————————————————————————————————————————————————————————————

• Comment: The heading notes that there are two different rates for group B soils, but only one is displayed. The old manual used to have a 0.6 inches per hour rate for group B soils.

Response: As part of the MIDS project, a technical team evaluated the infiltration table and determined there should be one value for B soils (0.3 in/hr). The heading is corrected. This is an important change and we are discussing how to inform Manual users about these types of changes.

—————————————————————————————————————————————————————————————————————

• Comment: This (Stormwater pond/wetland O & M checklist) is a very comprehensive list; most of the criteria would be helpful. It should be reformatted so that it prints more clearly and in a smaller number of pages. A 4 page check list when you are inspecting a pond is too much.

Response: In the header for select checklists we have added an option to access an Excel version of the checklist

—————————————————————————————————————————————————————————————————————

• Comment:The requirement for two year monitoring seems extremely hard on these systems. Monitoring requirements are not stipulated, pre-installation monitoring is required to characterize the runoff etc. No one in their right mind will do this on every site installation. Take into account that field monitoring devices themselves have been shown to be extremely inaccurate. With the move to MID design standards all tools are valid and for urban redevelopment underground systems may be the best option for the site. I strongly recommend replacing the monitoring requirement with a more stringent design process, say sizing on 50 um lab test using a treatment flow rate developed from the design storm event. Then require washout verification to say below 50 mg/l so that retention of sediment is also considered. A lot of work has been done at SAFL on this.

Response:This will not be required under the new CSW permit and it has therefore been removed.

—————————————————————————————————————————————————————————————————————

• Comment: How about replacing these TP 40 maps with Atlas 14 which was has now been adopted by NOAA.

Response We have added a link to Atlas 14. The Stormwater Manual will be updated in the future.

—————————————————————————————————————————————————————————————————————

• Comment: The heading notes that there are two different rates for group B soils, but only one is displayed. The old manual used to have a 0.6 inches per hour rate for group B soils.

Response: As part of the MIDS project, a technical team evaluated the infiltration table and determined there should be one value for B soils (0.3 in/hr). The heading is corrected. This is an important change and we are discussing how to inform Manual users about these types of changes.

—————————————————————————————————————————————————————————————————————

• Comment: This (Stormwater pond/wetland O & M checklist) is a very comprehensive list; most of the criteria would be helpful. It should be reformatted so that it prints more clearly and in a smaller number of pages. A 4 page check list when you are inspecting a pond is too much.

Response: In the header for select checklists we have added an option to access an Excel version of the checklist

—————————————————————————————————————————————————————————————————————

• Comment:The requirement for two year monitoring seems extremely hard on these systems. Monitoring requirements are not stipulated, pre-installation monitoring is required to characterize the runoff etc. No one in their right mind will do this on every site installation. Take into account that field monitoring devices themselves have been shown to be extremely inaccurate. With the move to MID design standards all tools are valid and for urban redevelopment underground systems may be the best option for the site. I strongly recommend replacing the monitoring requirement with a more stringent design process, say sizing on 50 um lab test using a treatment flow rate developed from the design storm event. Then require washout verification to say below 50 mg/l so that retention of sediment is also considered. A lot of work has been done at SAFL on this.

Response:This will not be required under the new CSW permit and it has therefore been removed.