What's New

This page provides a summary of significant recent changes to this website. We anticipate this page will be updated infrequently.

Information: For more detailed information about some of the updates described below, see Minnesota Stormwater Manual email Updates

• November 7, 2022
  • TP and TSS credits and guidance for manufactured treatment devices (mtds)
  • Guidance and recommendations for storing transported snow and for on-site snow storage
  • Operation and maintenance considerations for vegetation in stormwater management
  • Assessing the performance of iron enhanced sand filter
  • Identifying and characterizing redoximorphic features in soils and soil borings
  • Street sweeping updates
    • Overview, water quality benefits, and other co-benefits of street sweeping
    • Recommended practices for a water quality-targeted street sweeping program
    • File:Fact sheet - recommended practices for a water quality targeted street sweeping program.docx
    • Composition, characterization, and management of street sweepings
    • Accounting for phosphorus load reductions with street sweeping
    • Cost and maintenance information for street sweeping for water quality
    • Street Sweeping Phosphorus Credit Calculator
  • Green infrastructure updates
    • Operation and maintenance of green stormwater infrastructure best management practices
    • Planning green stormwater infrastructure projects and practices
    • Green infrastructure and green stormwater infrastructure terminology
    • Green Infrastructure benefits of bioretention
    • Green Infrastructure benefits of tree trenches and tree boxes
    • Green Infrastructure benefits of permeable pavement
    • Green Infrastructure benefits of constructed wetlands
    • Green Infrastructure benefits of vegetated swales
    • Green Infrastructure benefits of harvest and use/re-use practices
    • Green Infrastructure benefits of green roofs
• March 28, 2022:
  • Operation and maintenance (O&M) of Green stormwater infrastructure (GSI)
    • Operation and maintenance of bioretention and other stormwater infiltration practices
    • Operation and maintenance (O&M) of tree trenches and tree boxes
    • Operation and maintenance (O&M) of green roofs
    • Operation and maintenance (O&M) of swales
    • Operation and maintenance (O&M) of filter strips
    • Operation and maintenance (O&M) of stormwater and rainwater harvest and use/reuse practices
    • Operation and maintenance (O&M) of stormwater treatment wetland practices
    • Operation and maintenance (O&M) of permeable pavement
  • Street sweeping updates
    • Street sweeping overview
    • Street sweeping equipment
    • Benefits of street sweeping
    • Effectiveness of street sweeping (locations, timing, frequency)
    • Managing street sweeping waste
    • Cost considerations
    • Training for street sweeping professionals
    • Street Sweeping program development
    • References
  • Information on soils
  • Sand filter
• March 25, 2021: Several updates since the last update
  • The Green Infrastructure section of the Manual was reorganized and several case studies were added. On-going work on Green Infrastructure continues, with a focus on operation and maintenance, and on GI project planning.
  • The street sweeping section of the manual has been updated and new material added.
    • Street Sweeping Phosphorus Credit Calculator
    • Street Sweeping Phosphorus Credit Calculator: User Guide
    • Methods for sampling street sweeping material - Standard Operating Procedures
    • Methods for calculating pollutant reductions (credits) for street sweeping
    • Accounting for phosphorus load reductions with street sweeping
    • P8 Street Sweeping Modeling
  • Training and webinar schedule page added
  • Added a page called Tips for using the MIDS Calculator for tracking pollutant loading
  • Added a page called Summary of changes in Version 4 Minimal Impact Design Standards (MIDS) Calculator
  • Added a page called Spent lime, calcium water treatment residuals and application in stormwater
  • Added a page called Assessing total suspended sediment and total phosphorus removal efficiency of permittee owned/operated constructed stormwater ponds
  • Added a page called Aluminum and iron water treatment residuals and application in stormwater
  • Added a page called Biochar and applications of biochar in stormwater management
• December 1, 2020: A new page has been created called Assessing total suspended sediment and total phosphorus removal efficiency of permittee owned/operated constructed stormwater ponds. This page provides guidance related to assessing the total suspended sediment (TSS) and total phosphorus (TP) removal efficiency of MS4 (Municipal Separate Storm Sewer System) permittee owned/operated ponds constructed and used for the collection and treatment of stormwater. Four (4) evaluation strategies are discussed.
• December 1, 2020. Lots of new information has been added on TMDLs and the MS4 permit. A list of and links to new pages is provided below.
  • Summary of TMDL requirements in stormwater permits - updated
  • Guidance for completing the MS4 Permit TMDL Application Form
  • Guidance for meeting chloride TMDL MS4 permit requirements
  • Guidance for meeting bacteria TMDL MS4 permit requirements
  • Guidance for meeting dissolved oxygen or oxygen demand TMDL MS4 permit requirements
  • Guidance for meeting temperature TMDL MS4 permit requirements
  • Guidance for categorical TMDLs - updated
  • List of Approved TMDLs with MS4 WLAs - updated
  • Forms, guidance, and resources for completing the TMDL annual report form
  • Baseline year
  • Interpreting wasteload allocations based on flow/load duration curves
  • Overview of models used to meet MS4 TMDL permit requirements
  • Recommendations and guidance for utilizing P8 to meet TMDL permit requirements
  • Case study for using P8 to meet TMDL permit requirements
  • Recommendations and guidance for utilizing WINSLAMM to meet TMDL permit requirements
  • Case study for using WINSLAMM to meet TMDL permit requirements
  • Recommendations and guidance for utilizing the MIDS calculator to meet TMDL permit requirements
  • MIDS calculator
  • Case study for using the MIDS calculator to meet TMDL permit requirements
  • Recommendations and guidance for utilizing the MPCA Simple Estimator to meet TMDL permit requirements
  • Guidance and examples for using the MPCA Estimator
  • Case study for using the MPCA Simple Estimator to meet TMDL permit requirements
  • MPCA review of submittals using the MPCA Simple Estimator
  • Recommendations and guidance for utilizing monitoring to meet TMDL permit requirements
  • Recommendations and guidance for utilizing lake monitoring to meet TMDL permit requirements
  • Recommendations and guidance for utilizing stream monitoring to meet TMDL permit requirements
  • Recommendations and guidance for utilizing major stormwater outfall monitoring to meet TMDL permit requirements
  • Recommendations and guidance for utilizing stormwater best management practice monitoring to meet TMDL permit requirements
• Quick guides for using models to meet MS4 TMDL permit requirements
• Case studies for monitoring to meet TMDL permit requirements
• March 16, 2020: We have been working on updates to information on event mean concentrations for phosphorus and total suspended solids. This information will be used in updates to the MIDS Calculator and MPCA Simple Estimator.
  • Event mean concentrations of total suspended solids in stormwater runoff
  • Event mean concentrations of total and dissolved phosphorus in stormwater runoff
• January 7, 2020: We created a new page called Municipal Separate Storm Sewer System (MS4) toolkit. This page contains educational resources for stormwater programs. Additional materials will be added to the page as they are created throughout the year.
• October 3, 2019: New pages on pretreatment sizing - Pretreatment sizing for basins and filters strips and Technical basis for pretreatment sizing for basins and filter strips
• September 10, 2019: We have been creating several pages related to guidance for TMDLs. Most of these pages are under review and some are still in development. We anticipate having these pages fully reviewed by the end of September in advance of public noticing the MS4 permit. Pages are listed below.
  • Summary of TMDL requirements in stormwater permits
  • Forms, guidance, and resources for completing the TMDL annual report form
  • Guidance for meeting bacteria TMDL MS4 permit requirements
  • Guidance for meeting dissolved oxygen or oxygen demand TMDL MS4 permit requirements
  • Guidance for meeting temperature TMDL MS4 permit requirements
  • Overview of models used to meet MS4 TMDL permit requirements
  • Recommendations and guidance for utilizing P8 to meet TMDL permit requirements
  • Case study for using P8 to meet TMDL permit requirements
  • Recommendations and guidance for utilizing WINSLAMM to meet TMDL permit requirements
  • Case study for using WINSLAMM to meet TMDL permit requirements
  • Recommendations and guidance for utilizing the MIDS calculator to meet TMDL permit requirements
  • MIDS calculator
  • Case study for using the MIDS calculator to meet TMDL permit requirements
  • Recommendations and guidance for utilizing the MPCA Simple Estimator to meet TMDL permit requirements
  • MPCA Simple Estimator
  • Case study for using the MPCA Simple Estimator to meet TMDL permit requirements
  • Recommendations and guidance for utilizing monitoring to meet TMDL permit requirements
  • Case studies for monitoring to meet TMDL permit requirements
• September 10, 2019: We have updated the page on compost. The page was largely reorganized, but some material was updated and some new information added.
• July 31, 2019: We created a new page called Occurrence and mechanisms of constructed stormwater ponds that do not effectively retain phosphorus
• July 31, 2019: We made some minor changes to the page called Mosquito control and stormwater management, including adding a section summarizing more recent work on this topic.
• July 30, 2019: The MPCA received a request to develop information on management and disposal of sediment collected in stormwater pretreatment practices. We created a page called Guidance for managing sediment and wastes collected by pretreatment practices. Note the MPCA does not provide specific recommendations for managing and disposing sediment collected from pretreatment practices. This page provide guidance, a literature review, and a summary of some sampling data from the literature.
• July 1, 2019 - several updates to the Pretreatment section of the manual
  • Pretreatment selection tool
  • Pretreatment - Hydrodynamic separation devices
  • Pretreatment - Screening and straining devices, including forebays
  • Pretreatment - Above ground and below grade storage and settling devices
  • Pretreatment - Filtration devices and practices
  • Pretreatment - Other pretreatment water quality devices and practices
  • Pretreatment tables - link to tabled information for pretreatment practices
  • Hydrodynamic separator tables
  • Screening and straining devices tables
  • Above ground and below grade storage and settling tables
  • Filtration tables
  • Other water quality devices tables
  • Case studies for pretreatment
• May 29: Several new pages pertaining to construction stormwater
  • Winter construction practices for site stabilization, erosion prevention and sediment control
  • Construction stormwater treatment - dewatering, including chemical treatment and sediment filtration
  • Erosion prevention practices - Riprap
  • Construction stormwater practices - temporary stream crossing
  • Construction stormwater practices - diversion and working in the dry
  • Construction stormwater treatment - BMP removal after final stabilization
• May 22, 2019: We've been busy adding case studies for swales and pretreatment. These pages are under review/construction at this time, but if you have comments please use the comment box at the bottom of the pages.
  • Case studies for pretreatment
  • Case studies for dry swale (grass swale)
  • Wet swale case study
  • Step pool case study
• April 3, 2019: We've begun utilizing a new feature called "hover boxes". On new or updated pages, holding your mouse over bolded text will reveal a definition or explanation of the text. This tool is not widely utilized yet as incorporating it into existing pages is a low priority. Over time, the feature will become more prevalent.
• March 21, 2019: Three new pages on sediment control practices have been added.
  • Sediment control practices - Sediment traps and basins
  • Sediment control practices - Stabilized earth/soil berm
  • Construction stormwater best management practice – buffer zones
• March 21, 2019: Two new pages related to the Construction Stormwater permit have been added.
  • Who needs a Construction Stormwater Permit?
  • Construction Stormwater Permit timelines
• January 23, 2019: We created a new page that provides information and recommendataions for maximizing volume retention in the MIDS calculator. See MIDS calculator tips and information for maximizing volume retention
• December 14, 2018: We've added three examples to the page titled Guidance and recommendations for conducting a higher level of engineering review for stormwater infiltration in DWSMAs and Wellhead Protection Areas. These examples cover situations where a higher level of engineering review is required to utilize infiltration practices in a Drinking Water Source Management Area (DWSMA). When reviewing this section, note that we utilize a new feature called "hover boxes". Holding your mouse over any bolded text will reveal a definition or explanation of the text.
• December 3, 2018: Using a new extension in the wiki, we added an interactive image illustrating 10 Steps to Stormwater Pollution Prevention on Small Residential Construction Sites
• October 4, 2018: The Interstate Technology and Regulatory Council (ITRC) released a new guidance document called Stormwater Best Management Practices Performance Evaluation. This Stormwater BMP guidance offers the user details on post construction BMP lifecycle processes including contracting, cost considerations, installation factors including construction challenges, inspection checklists, and quality control and record drawings. It goes on to address long-term technology- and performance-based operational strategies, including aspects such as routine and non-routine maintenance. Data and information from existing publicly available BMP performance programs has been incorporated into an online BMP Screening Tool. Using site-specific pollutant treatment requirements and installation considerations, the Tool can assist the user by identifying a list of BMPs that may be appropriate for a given site. The Tool also provides users summarized information on the treatment efficiency, installation requirements and maintenance issues regarding the identified BMPs, with links to access more detailed information.
  • Click HERE to access the Stormwater document.
  • Click HERE to access the BMP Screening Tool.
  • Click HERE to watch our Stormwater BMP videos.
• August 22, 2018: We've been busy updating the stormwater wiki to ensure everything is consistent with the new Construction Stormwater permit. In addition to many subtle changes in text throughout the wiki, the following pages have undergone significant updates to be consistent with the new permit.
  • 2018 permit - an electronic version of the CSW permit
  • File:What's new in the 2018 Construction Permit.pdf - a summary of changes from the 2013 permit
  • Stormwater infiltration and contaminated soils and groundwater - The CSW permit requires permittees to complete a site assessment before proceeding with infiltration at sites where contaminants may be mobilized by infiltrating stormwater. MPCA developed a Screening assessment for contamination at potential stormwater infiltration sites, which includes a checklist that permittees can use to meet the permit requirement. The assessment page provides guidance for completing a site assessment and the checklist. The assessment page includes four examples, information on appropriate separation between contaminants and stormwater infiltration practices, and numerous links to tools and guidance for investigating sites that may have contaminated soils or groundwater.
  • Stormwater and wellhead protection - Infiltration requirements at sites within Drinking Water Source Management Areas (DWSMAs) are considerably less restrictive than the 2013 CSW permit. This page reflects changes in the permit, includes an updated flowchart for determining if infiltration is appropriate or prohibited at a site, has a schematic with six examples, and provides numerous links.
  • Guidance and recommendations for conducting a higher level of engineering review for stormwater infiltration in DWSMAs and Wellhead Protection Areas - a new page to help permittees understand how to complete a higher level of engineering review at sites in DWSMAs.
  • Guidance for using the Stormwater Special and impaired waters search tool - a new page demonstrating how to use the Special and impaired water mapping tool to determine permit compliance.
  • When infiltration is not authorized under a stormwater permit - this page has been updated to reflect CSW permit changes related to post-construction infiltration practices.
• May 22, 2018
  • We updated a table on design considerations for phosphorus. The MPCA hopes to contract work in the near future to update design information for phosphorus retention in constructed ponds.
  • We've added alerts to several pages addressing credits. The alerts state that models used for compliance with the Construction Stormwater permit must meet the instantaneous volume retention requirement.
• April 19, 2018: Information on swales has been updated. This includes three BMPs and associated sections: dry swale, wet swale, and stormwater step pool. Each of the links shown in the previous sentence takes you to a table of contents for each of the three BMP types. Each BMP type includes pages on design, construction, operation and maintenance, assessment, cost considerations, and credit calculations. In addition, the following pages may be of interest.
  • Terminology for swales
  • Types of filtration
  • Plants for swales
  • Check dams for stormwater swales
• October 25, 2017: We have updated several sections on stormwater and rainwater harvest use/reuse. Some of these were mentioned in an October 20 update and are included again in the following summary.
  • Collection (conveyance): https://stormwater.pca.state.mn.us/index.php?title=Design_criteria_for_stormwater_and_rainwater_harvest_and_use/reuse#Collection
  • Pump demand: https://stormwater.pca.state.mn.us/index.php?title=Design_criteria_for_stormwater_and_rainwater_harvest_and_use/reuse#Pump_demand
  • Estimating water budget: https://stormwater.pca.state.mn.us/index.php?title=Estimating_the_water_balance_for_a_stormwater_and_rainwater_harvest_and_use/reuse_site
  • Determining storage size: https://stormwater.pca.state.mn.us/index.php?title=Determining_the_appropriate_storage_size_for_a_stormwater_and_rainwater_harvest_and_use/reuse_system
  • Design considerations for ponds used for harvest and use/reuse: https://stormwater.pca.state.mn.us/index.php?title=Design_considerations_for_constructed_stormwater_ponds_used_for_harvest_and_irrigation_use/reuse
  • Case studies: https://stormwater.pca.state.mn.us/index.php?title=Case_studies_for_stormwater_and_rainwater_harvest_and_use/reuse
• October 20, 2017: New information has been added on roofs, gutters, and downspouts to the collection section on the page Design criteria for stormwater and rainwater harvest and use/reuse.
• October 20, 2017: We have included three new case studies on the page Case studies for stormwater and rainwater harvest and use/reuse
• October 20, 2017: We have updated the section on pumps on the page Design criteria for stormwater and rainwater harvest and use/reuse. New information includes the following:
  • Pump peak demand
  • Estimating peak demand
  • Sample calculations of peak demand
• October 19, 2017: While we are encouraged to see increased use of amendments to address phosphorus concerns, there still appears to be widespread use of biofiltration media that can leach phosphorus, potentially contributing to downstream water quality impairments. We thus added a short section in the manual offering some recommendations for avoiding P export from biofiltration media. We hope to expand this section as additional research is completed and as we gather more information on the use of amendments to attenuate phosphorus.
• September 28, 2017: We built two pages that provide some information on costs.
  • Success stories: salt reduction and cost saving examples
  • Information on costs and economic impacts of road salt
• August 31, 2017: A new page called Design considerations for constructed stormwater ponds used for harvest and irrigation use/reuse has been added. The material on this page has also been added to the design sections for construced stormwater ponds and harvest and use/reuse.
• August 25, 2017: We are updating the MS4 page, which is called Stormwater Program for Municipal Separate Storm Sewer Systems (MS4). The basic structure of the page has been updated. Note that many of the newly created pages have minimal information. Check in periodically as we hope to populate these pages over time. We have created a new page called Summary of data received from permittees on MS4 TMDL permit reporting forms. This page summarizes information we received from permittees who reported on Total Maximum Daily Loads.
• June 2, 2017: Updated the Future Updates page.
• April 20, 2017: We are attempting to do more outreach in an effort to disseminate information from the manual and the MPCA Stormwater Program
  • Webinars: We have held three webinars to date. See here for more information.
  • Newsletters: We distribute a quarterly newsletter. Link here. Note this page includes links to newsletters distributed by other organizations. To get on our newsletter distribution list, link here.
  • Stormwater blog: link here.
• March 2, 2017: We are in the process of adding MS4 pollution prevention fact sheets to the MS4 page. The fact sheets can be found here. Note that new fact sheets are being developed and thus some of the fact sheets may not yet be properly formatted, but we'll continue the process of getting these in final format as quickly as we can. These fact sheets come from a report called Prevention and the MS4 Program: A Guide on Utilizing Pollution Prevention Activities to Meet MS4 General Permit Requirements.
• February 15, 2017: The following new pages have been created.
  • Stormwater infiltration at permitted industrial stormwater facilities
  • Using the Minnesota Stormwater Manual and MIDS Calculator to help meet industrial stormwater permit requirements
  • When infiltration is not authorized under a stormwater permit
  • Phosphorus in stormwater
• January 23, 2017: A new page has been added called Design, construction, operation and maintenance specifications for pretreatment vegetated filter strips.
• January 17, 2017: Version 3 of the MIDS calculator is now available. To download the calculator, link here. To see changes from Version 2, link here. These pages provide information on requirements, recommendations and information for using specific BMPs in the MIDS calculator. Each page includes one or more example.
  • Underground infiltration BMPs
  • Harvest and reuse/use
  • Impervious disconnection
• January 9, 2017: A new section in the manual has been created called Stormwater and rainwater harvest and use/reuse. This section contains multiple pages, which are summarized below.
  • Overview for stormwater and rainwater harvest and use/reuse
  • Design criteria for stormwater and rainwater harvest and use/reuse
  • Construction specifications for stormwater and rainwater harvest and use/reuse
  • Operation and maintenance for stormwater and rainwater harvest and use/reuse
  • Water quality considerations for stormwater and rainwater harvest and use/reuse
  • Environmental concerns for stormwater and rainwater harvest and use/reuse
  • Cost-benefit considerations for stormwater and rainwater harvest and use/reuse
  • Case studies for stormwater and rainwater harvest and use/reuse
  • Calculating credits for stormwater and rainwater harvest and use/reuse
  • Definitions for stormwater and rainwater harvest and use/reuse
  • Requirements, recommendations and information for using Harvest and re-use/cistern as a BMP in the MIDS calculator
  • References for stormwater and rainwater harvest and use/reuse
  • Technical support for stormwater and rainwater harvest and use/reuse
• November 2, 2016: We continue to update information on construction stormwater, including migrating and updating information from Chapter 6 of the Stormwater Best Management Practices Manual (i.e. the Blue Book). We've added four pages to the section on Sediment control practices. Those four pages, with links, are shown below. We'll continue to update this section of the manual in the coming weeks and will post updates periodically as new pages are created.
  • Sediment control practices - Vehicle tracking BMPs
  • Sediment control practices - Perimeter controls for disturbed areas
  • Sediment control practices - Check dams (ditch checks, ditch dikes)
  • General principles for erosion prevention and sediment control at construction sites in Minnesota
• October 24, 2016: We are in the process of updating information on construction stormwater, including migrating and updating information from Chapter 6 of the Stormwater Best Management Practices Manual (i.e. the Blue Book). We've added three pages to the section on Sediment control practices. Those three pages, with links, are shown below. We'll continue to update this section of the manual in the coming weeks and will post updates periodically as new pages are created.
  • Sediment control practices - Diversion barrier controls (cofferdams/temporary dikes)
  • Sediment control practices - Storm drain inlet protection
  • Sediment control practices - Outlet energy dissipation
• July 21, 2016
  • The Manual page on pretreatment has been updated. You will notice links to several new pages.
    • Overview and methods of pretreatment
    • Overview for pretreatment settling devices
    • Overview for pretreatment screens
    • Overview for pretreatment vegetated filter strips
    • References for pretreatment
    • Definitions for pretreatment
  • We've created a page addressing stormwater infiltration at sites that may have or do have soil or groundwater contamination. It will take several months to fully populate this section of the manual, but we have created the following pages thus far.
    • Contaminated sites and stormwater infiltration
    • Screening assessment for contamination at potential stormwater infiltration sites
  • We've created a page called Understanding and interpreting soils and soil boring reports for infiltration BMPs
  • We've created a page called Case studies for infiltration practices
• June 8, 2016: A page called Construction stormwater photo gallery was added. This is a work in progress and will be expanded over time.
• May 24, 2016. We added a page called Pollinator friendly Best Management Practices for stormwater management. This page provides numerous links to information that can be used in designing and implementing pollinator-friendly stormwater BMPs.
• May 24, 2016. We added a page called Virtual tours. This page includes links to other organization’s web sites in Minnesota that have virtual tours-good maps of their stormwater BMP’s.
• March 25, 2016. We have added a new page called Information for determining stormwater management impacts for solar projects.
• March 1, 2016. We are in the process of updating information on road salt, smart salting, and winter maintenance. Visit the main page on this topic to see what pages have been updated or added (shown in blue text) and pages that are anticipated being updated or added (red text). Note the Winter Maintenance Assessment tool (WMAt) is now available.
• March 1, 2016. We have updated the page on stormwater infiltration in Wellhead Protection Areas. This page includes revised guidance on infiltration in Drinking Water Supply Management Areas. This new guidance, developed jointly by the Minnesota Department of Health and Minnesota Pollution Control Agency, replaces earlier guidance on stormwater infiltration developed by the Minnesota Department of Health.
• December 29, 2015. Two pages on stormwater models and modeling have been updated.
  • Introduction to stormwater modeling
  • Available stormwater models and selecting a model
• December 15, 2015. We have drafted a page on liners for stormwater management. Previously the manual had scattered and inconsistent information on liners. We utilized information from other states to develop this page. Note that we refer readers to supporting information primarily developed in Wisconsin. An extensive reference list is included.
• July 29, 2015. The page Using the treatment train approach to BMP selection has been updated. To accompany the information on treatment trains, several pages provide example scenarios for developing treatment trains.
  • Scenario for developing a stormwater treatment train for a parking lot
  • Scenario for developing a stormwater treatment train for an ultra-urban setting
  • Scenario for developing a stormwater treatment train for a site with limited infiltration capacity
  • Scenario for developing a stormwater treatment train for a retrofit site
  • Scenario for developing a stormwater treatment train for constructed ponds in new development

Another page provides case studies of treatment trains. See Case studies for stormwater treatment trains.

• July 20, 2015. The Main Page and Table of Contents have been changed to allow for easier and more logical searching and movement within the manual website. The structure is similar to that of Wikipedia, utilizing the concept of portals to major topic areas. Comments are welcome (mail to [1]).
• July, 2015. The MPCA will begin work on 3 new areas of work in the manual: Pretreatment, construction stormwater (to replace the Blue Book) and infiltration devices. Technical teams are being formed and the work will begin in August. New work will also begin on stormwater harvest and use in the fall.
• June, 2015. Several pages addressing the topic of stormwater credits for runoff volume and pollutants have been added. These are under review through the month of June. These pages are specific to credits for individual BMPs. Each page is formatted similarly and contains information on the basis of credits for the BMP, methods for determining credits, recommended values, and references. Links to these pages can be found here.
• We have added a new page called In the News. You can find it in the left toolbar. If you are aware of a newsworthy event in the stormwater world, send us an email. We don't guarantee including it on the page, but we'll give it a look.
• February 24, 2015. We have created two pdf documents containing sections of the Manual. One is for iron enhanced sand filters and the other is for green roofs. These were created using the Create a Book function in the left toolbar. NOTE that these documents have not been formatted in the manner typical for pdf documents and instead compile different articles from the wiki. There may therefore be unusual formatting. Using the Create a Book function you can build a customized document containing multiple pages from the Manual. See [2] for help on creating a book. If you have an interest in other pdf documents being created, submit a comment using the Help Improve this Page box at the bottom of this page or submit an email to us.
• February 24, 2015. Several pages have been created related to the TMDL Reporting Form, which is a form that must be submitted by MS4 permittees that have TMDL Wasteload Allocation requirements approved by the U.S. EPA prior to August 1, 2013. The following pages have been added.
  • An upload page containing individual TMDL Reporting Forms for those permittees required to submit a form by June 30, 2015.
  • Guidance for completing the TMDL Reporting Form. Quick guides are also available for different sections of the Reporting Form (Activities completed tab and Cumulative reductions tab).
  • Examples for completing the Reporting Form
• January 29, 2015
  • The original Manual recommended using the lowest infiltration rate within 5 feet of the bottom of the BMP when designing an infiltration BMP. In 2013 this was changed to 3 feet based on data presented for other states. Based on our experience over the past year, we are recommending returning to the 5 foot depth. This builds in a factor of safety for situations where you may have a low permeability unit right at the minimum 3 foot separation distance. We have revised the Manual to reflect this 5 foot recommended distance. Therefore, when designing an infiltration practice, use the lowest permeability unit within 5 feet of the bottom of the practice, or, if the separation distance is less than 5 feet, the lowest permeability unit within that separation distance.
  • If using permeameter tests to determine the soil infiltration rate at a site, the recommended number of measurements is 5 per each additional 5000 square feet of area. For large sites, this can result in a large number of samples. We have included a recommendation that the number of permeameter tests may be reduced under certain conditions. One method to determine the number of samples is to plot standard deviation versus sample number. At a point where the curve flattens, infiltration testing may be halted. A minimum of 5 samples is recommended. For more information, see the NOTE in [3].
• January 26, 2015. We continue to make minor changes to the Manual. Some of these changes may be noteworthy and are summarized below.
  • A new page on BMP terminology has been added. This page summarizes the various math terms used throughout the Manual. We initially noticed several inconsistencies in terminology as the Minimal Impact Design Standards work progressed. We believe most of those inconsistencies have been addressed. However, some terminology from the original manual still needs to be addressed and we will trying to update that information over the next couple months.
  • The Construction Stormwater permit requires the water quality volume of one (1) inch of runoff from the new impervious surfaces created by a permitted project to be retained on site (i.e. infiltration or other volume reduction practices) and not discharged to a surface water. The 1 inch represents an instantaneous volume of water captured by the BMP. We are therefore in the process of updating sizing calculations to be consistent with the permit. For an example, see [4].
  • A literature review of bacteria removal in filtration practices shows the removal percentages in the original manual were too high, particularly for vegetated practices. Removal percentages in the original manual were 70 percent for both media and vegetated filters. The values have been updated to 50 percent for media filters and 0 percent for vegetated practices. We anticipate conducting a more thorough literature review in the future to clarify these values.
  • We have expanded the discussion of suspended pavements for tree practices to include Strata cells in addition to Silva cells. See [5]. We have also updated information on soil volume requirements for rock-based systems for tree practices. See [6].
• November 19, 2014. We created a new page called Alleviating compaction from construction activities. This page does not present new information on this topic, but instead brings existing information on alleviating compaction, currently scattered in different places in the manual, onto a single page.
• November 4, 2014. The Tree section of the Manual has been undergoing updates over the past several months. The section is now fully updated

The most recent information on this topic includes the following:

• Design guidelines for tree quality and planting - tree trenches and tree boxes;
• Construction guidelines for tree trenches and tree boxes;
• Protection of existing trees on construction sites;
• Operation and maintenance of tree trenches and tree boxes; and
• Assessing the performance of tree trenches and tree boxes.

NOTE: A street sweeping spreadsheet calculator tool, developed by Kalinosky et al.(2013) and referenced on the street sweeping section of the Manual is now available.

• August 29, 2014: New pages have been added discussing and illustrating the following:
  • Requirements, recommendations and information for using bioretention with an underdrain BMPs in the MIDS calculator
  • Requirements, recommendations and information for using infiltration basin/underground infiltration BMPs in the MIDS calculator
  • Requirements, recommendations and information for using stormwater pond as a BMP in the MIDS calculator
• August 26, 2014
  • A new page has been added discussing and illustrating Requirements, recommendations and information for using green roofs as a BMP in the MIDS calculator
  • A new page has been added discussing and illustrating Requirements, recommendations and information for using permeable pavement BMPs in the MIDS calculator
• August 19, 2014: A new page has been added discussing and illustrating the use of performance curves for the MIDS calculator.
• August 19, 2014: A new page has been added to provide guidance on using the Minimal Impact Design Standards (MIDS) calculator. The page addresses bioretention systems without an underdrain (bioinfiltration).
• August 18, 2014: Four pages have been added to provide guidance on using the Minimal Impact Design Standards (MIDS) calculator. These pages provide guidance and examples for using the MIDS calculator for the following BMPs.
  • Swale with an underdrain
  • Wet swale
  • Swale side slope
  • Sand filter
• August 13, 2014: A page has been added to provide guidance on using the Minimal Impacts Design Standards (MIDS) calculator. This page provides a description of how the calculator treats swales with no underdrain, how credits for volume, phosphorus and TSS are calculated, guidance on using the calculator for swales with no underdrain, and provides an example application of the calculator for this BMP. See Requirements, recommendations and information for using swale without an underdrain as a BMP in the MIDS calculator.
• July 22, 2014: An updated version of the Minimal Impact Design Standards calculator has been released. The newest version of the calculator includes the following updates from the previous version.
  • Tree trench/box credits for canopy interception and evapotranspiration
  • Bioretention with underdrain updated to apply the equation for phosphorus credit reduction based on media depth.
  • Summary table of total phosphorus and total suspended solids percent removal by BMP on the summary tab of the calculator
  • Annual runoff volumes to BMP summary tab was added
  • Bioretention media phosphurus credits to tree box/infiltration trench with underdrain
  • Bioretention medial phosphorus credits to swale with underdrain was added
  • Sizing inputs for stormwater ponds
  • Swale annual TSS, dissolved phosphorus and particulate phosphorus removals were adjusted
  • A stormwater reuse function!
• July 22, 2014: Two pages have been added to provide guidance on using the Minimal Impacts Design Standards (MIDS) calculator. These pages provide a description of how the calculator treats tree trenches/tree boxes, how credits for volume, phosphorus and TSS are calculated, guidance on using the calculator for tree trench/tree box BMPs, and provides example applications of the calculator for these BMPs.
  • Requirements, recommendations and information for using trees as a BMP in the MIDS calculator
  • Requirements, recommendations and information for using trees with an underdrain as a BMP in the MIDS calculator
• May 19, 2014: The Minimal Impact Design Standards (MIDS) Community Assistance Package (CAP) is available.
• April 23: A page addressing stormwater management for lake protection and restoration has been added. The page primarily brings information and links relevant to lake management from other places in the manual together in a single location.
• March 25: A section on Operation and maintenance of tree trenches and tree boxes has been added.
• February 27: The section on design criteria for bioretention has been updated. New and updated information is summarized in a table.
• February 27: The section on construction specifications for bioretention has been updated. This includes new information on soil compaction and alleviating soil compaction, bioretention mixes and planting.
• February 12: A section on road salt has been added. For now, the section is very general and primarily contains links to other sites. We are working with a contractor to enhance this site and it should be updated in late summer, 2014.
• February 3: The Minimal Impact Design Standards calculator is now available.
• January 30: New information on pollutant removal by BMPs has been added. This page includes information on TSS and TP outflow concentrations and removal percentages for ponds, wetlands, grass filters, and sand filters, as well as additional discussion on pollutant removal for bioretention and infiltration BMPs.
• January 30: A table summarizing phosphorus reduction credits has been added.
• January 30: A section on soil amendments to enhance phosphorus sorption has been added.
• January 29: A section on funding has been added in the left column of the navigation page. We added a description of funding opportunities for stormwater projects. You will find information on projects that were recently funded with Clean Water Land and Legacy funds. We also started adding projects that are currently and previously funded. We will continue to add projects to the list.
• January 15: We updated existing information on bioretention mixes A and B and added information for two new mixes (C and D). These mixes are summarized in a table. NOTE that there are recommended changes for Mixes A and B. Mixes C and D were included because they are considered to retain phosphorus, while mixes A and B are considered to leach phosphorus.
• January 15: We added a section on design guidelines for soil characteristics for tree trenches and tree boxes. The site is under review through February.
• January 3: We continue to add material to the section on Trees. The material on the site is currently under either construction or review. Additional material on design guidelines, construction, maintenance, and monitoring of tree trenches and tree boxes will eventually be added. We hope to have the site fully populated within the next month, although it will remain under review for some time after that.
• January 3: We have added some items to the Events page. If you are aware of events that are appropriate for posting, please let us know via the comment box. NOTE: the MPCA cannot promote or endorse specific products, companies, etc. and we must therefore be selective about what events are posted at this site.
• December 20: The phosphorus removal efficiency for bioretention BMPs has been changed. Previously, a single value of 60 percent was given for this BMP. The new values are 100 percent for water that is infiltrated, 25 percent for water that passes through an underdrain, and 0 percent for water that bypasses the bioretention BMP. See Pollutant removal percentages for bioretention BMPs. This change is likely temporary as a technical workgroup is evaluating phosphorus removal rates for bioretention BMPs. Factors such as initial soil/media phosphorus content, depth above an underdrain, and presence of P-sorbing amendments in the soil/media will affect the removal efficiency of the BMP. It is anticipated the recommendations of the workgroup will be incorporated into the Manual in mid- to late January.
• December 16: Following a meeting of technical experts, an infiltration rate of 0.45 inches per hour was established for SM soils. The rate for these soils was previously 0.3 inches per hour. In the original Manual the rate for these soils was 0.6 inches per hour. See Design infiltration rates.
• December 4: We added information to the section on trees. This includes an overview, several tables listing properties for several tree species, and supporting material. We have additional information on trees that will be added in the next couple months, including design guidelines, construction specifications, and more.
• October 9: The section on Vegetated filter strips has been updated.
• September 26: We added two links in the left toolbar. The first is Categories, which provides a shortcut to the list of categories. Categories are basically an index of similar webpages. For example, one of the categories is Photos, which shows all the photos in the wiki. Results of our recent survey suggest people frequently use the Categories feature. The second link in the left toolbar is Response to comments. Unfortunately there is no easy way to display our responses to comments submitted via the Comment box on each page. Clicking on the comment link in the left toolbar shows most comments we receive along with our reply. We encourage people to submit comments using the Comment box on the bottom of each page. Comments can be on content of a page, suggested edits, errata, comments on wiki functionality, etc.
• August 2: A section on filter strips (as pre-treatment) has been added.
• July 16: A section on green roofs has been added. The section includes several pages (articles) discussing different aspects of green roofs, including general terminology, information on design, construction and maintenance, plant lists, references, case studies, and more.
• July 16: A separate page has been created called Information on pollutant removal by BMPs. The page contains links to tables showing data on pollutant removal, sections that contain information on pollutant removal, and external links to information on pollutant removal. The page was created to provide easy access to this data.
• May 21: Information on infiltration practices at contaminated (Brownfield) sites was added.
• May 7: A new section on iron enhanced sand filters was added. It will be open for review through June, 2013.
• April 15: Table with design infiltration rates
  • The table now contains one value for B soils (0.3 inches/hour). The previous version of the manual included rates of 0.3 and 0.6 inches/hour based on texture. The value of 0.6 was not supported by literature and a technical group determined there should be one value for B soils.
  • The design rate for D soils is 0.06 inches/hour. This replaces the previous value of <0.2 inches/hour and is in line with the Minimal Impact Design Standards calculator.
  • A/D, B/D, and C/D soils are assigned infiltration rates of 0.06 inches/hour, corresponding with a D soil. These soils are subject to seasonal high water tables, at which time they behave like a D soil.
• April 15: Safety factors - safety factors, previously called correction factors, are applied to field measured infiltration rates. They are intended to account for natural variability in infiltration rates of soils and in decreased infiltration performance of a BMP over time. A safety factor of 2 shall be applied to infiltration BMPs other than permeable pavement. A safety factor of 2.5 shall be applied to permeable pavement. For example, a measured infiltration rate for a bioretention system of 1.0 inches per hour shall be divided by the safety factor of 2, resulting in an infiltration rate of 0.5 inches per hour. In Version 2.X of the Manual, safety factors were calculated using information in a table.

We completed migration of content from the 2008 Manual to this website during the last week of March, 2013. We do not anticipate further significant changes in Manual content during the wiki website rollout in April. Following that, we hope to incorporate the following changes into the Manual:

• new information on green roofs in May and June;
• updates to the bioretention section in early to mid summer
• incorporation of information on trees in late summer and early fall;
• new sections on stormwater Minimal Impact Design Standards; and
• new information on iron-enhanced filters this summer.

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