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Minnesota Stormwater Manual

MIDS design sequence flow chart
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Box 1

Did you gather the site information necessary to proceed through the flow chart?

Yes

No or Unsure

Box 2

Prior to using the flow chart, gather the following preliminary information.

  • Conduct site review
  • Define performance goal

Conduct site review

PROCEED TO THE NEXT STEP

Box 3

  • New and redevelopment projects: Retain on site a volume of 1.1 inches from impervious surfaces
  • Linear projects: Retain on site the larger of 1.1 inches from all new or 0.55 inches from all new and fully reconstructed impervious surfaces

PROCEED TO THE FIRST QUESTION

Links

Box 4

Does project create one acre or more of new and/or fully reconstructed impervious surfaces?

PREVIOUS QUESTION and ANSWER: The previous question defined the performance goals.

Box 5

MIDS PERFORMANCE GOAL DOES NOT APPLY
The project creates less than 1 acre of impervious surface.

Box 6

image of a project where ROW will not be constraining
Example of a linear project where site constraints likely do not exist
File:Example limited ROW.jpg
Example of a linear project where ROW will likely be constraining

Is the project linear?

Yes

No

PREVIOUS QUESTION and ANSWER: Does project create one acre or more of new and/or fully reconstructed impervious surfaces? Answer - Yes

Box 7

Are there constraints due to lack of available ROW, off site drainage and/or rate control requirements?

Yes

No

Box 8

Is Flexible Treatment Option (FTO) 2 feasible?

[ Box 57 Yes]

[ Box 10 No]

PREVIOUS QUESTION and ANSWER: Are there restraints due to lack of available right-of-way, off-site drainage, and/or rate control requirements? Answer: Yes

Box 9

image of stop sign
You have completed the flow chart. Return to Flexible treatment options

Select Flexible treatment Option 2. You have completed the flow chart.

  • Provide documentation of offsite runon to project area
  • Provide documentation of lack of right-of-way

Flexible Treatment Option 2 (FTO #2)

Applicant attempts to comply with the following conditions:

  1. Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
  2. Remove 60 percent of the annual total phosphorus load, and
  3. Options considered and presented shall examine the merits of relocating project elements to address varying soil conditions and other constraints across the site.

PREVIOUS STEP: It was determined that the site is linear, there are constraints due to lack of right-of-way or off/site drainage and/or rate control requirements, and a reasonable effort to acquire all of the right-of-way cannot be made.

Box 10

image of stop sign
You have completed the flow chart. Return to Flexible treatment options

SELECT FLEXIBLE TREATMENT OPTION 3

Off-site mitigation (including banking or cash or treatment on another project, as determined by the local authority) equivalent to the volume reduction performance goal can be used in areas selected in the following order of preference:

  1. Locations that yield benefits to the same receiving water that receives runoff from the original construction activity.
  2. Locations within the same Department of Natural Resources (DNR) catachment area as the original construction activity.
  3. Locations in the next adjacent DNR catchment area up-stream.
  4. Locations anywhere within the local authority's jurisdiction.

PREVIOUS QUESTION: It was determined that Flexible Treatment Option 2 is not feasible.

Box 11

Are there zoning and land use requirements that make the Performance Goal not feasible?

Yes

No

PREVIOUS QUESTION and ANSWER:

  • Is the project linear? Answer: No

or

  • Are there constraints due to lack of available ROW, off site drainage and/or rate control requirements? Answer: No

Box 12

Is BMP relocation feasible

Yes

No

PREVIOUS QUESTION and ANSWER: Are there zoning and land use requirements that make the Performance Goal not feasible? Answer: Yes

Box 13

Is Flexible Treatment Option (FTO) 1 feasible?

[ Box 61 Yes]

No

PREVIOUS QUESTION and ANSWER: Is BMP relocation feasible - Answer: No

Flexible Treatment Option 1 (FTO #1)

Applicant attempts to comply with the following conditions:

  1. Achieve at least 0.55 inch volume reduction goal, and
  2. Remove 75 percent of the annual total phosphorus load, and
  3. Options considered and presented shall examine the merits of reloacting project elements to address varying soil conditions and other constraints across the site

Box 14

Is Flexible Treatment Option (FTO) 2 feasible?

[ Box 54 Yes]

No

==PREVIOUS QUESTION and ANSWER: Is Flexible Treatment Option (FTO) 1 feasible? - Answer: No

Flexible Treatment Option 2 (FTO #2)

Applicant attempts to comply with the following conditions:

  1. Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
  2. Remove 60 percent of the annual total phosphorus load, and
  3. options considered and presented shall examine the merits of relocating project elements to address varying soil conditions and other constraints across the site.

Box 15

Is the site located in a DWSMA (Drinking Water Supply Management Area), wellhead protection area, or within 200 feet of a drinking water well?

Yes

No

Box 16

Can a Local Government Unit (LGU) provide a higher level of engineering review to ensure a functioning system that prevents adverse impacts to groundwater?

Yes

[ Box 58 No]

PREVIOUS QUESTION and ANSWER: Is the site located in a DWSMA, Wellhead Protection Area, or within 200 feet of a drinking water well? - Answer: Yes

Box 17

Are there existing or proposed structures or infrastructure (e.g. rate control BMPs, utilities, buildings, roadway, easements) that make the Performance Goal not feasible?

Yes

[ Box 21 No]

PREVIOUS QUESTION and ANSWER:

  • Is the site located in a DWSMA, wellhead protection area, or within 200 feet of a drinking water well? - Answer: No

or

  • Can a Local Government Unit (LGU) provide a higher level of engineering review to ensure a functioning system that prevents adverse impacts to groundwater? - Answer: Yes

Box 18

Is BMP relocation feasible?

Yes

No

PREVIOUS QUESTION and ANSWER: - Are there existing or proposed structures or infrastructure (e.g. rate control BMPs, utilities, buildings, roadway, easements) that make the Performance Goal not feasible? - Answer: Yes

Box 19

Is Flexible Treatment option (FTO) 1 feasible?

[ Box 62 Yes]

No

PREVIOUS QUESTION and ANSWER: Is BMP relocation feasible? - Answer: No

Box 20

Is Flexible Treatment Option (FTO) 2 feasible?

[ Box 54 Yes]

No

PREVIOUS QUESTION and ANSWER: Is Flexible Treatment Option (FTO) 1 feasible? - Answer: No

Flexible Treatment Option 2 (FTO #2)

Applicant attempts to comply with the following conditions:

  1. Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
  2. Remove 60 percent of the annual total phosphorus load, and
  3. options considered and presented shall examine the merits of relocating project elements to address varying soil conditions and other constraints across the site.

Box 21

Is karst present on the site?

Yes

No

If you are unsure, we recommend you review the guidance for karst in this manual. To retain your place in this flowchart, either open the karst guidance page in a new tab (right click on the link and select Open Link in New Tab), use the back arrow after visiting the karst guidance page, or use the Breadcrumbs at the top of the page.

PREVIOUS QUESTION and ANSWER:

  • Are there existing or proposed structures or infrastructure that make the performance goal not feasible? - Answer: No

or

  • Is BMP relocation feasible? - Answer: Yes

Box 22

Can a local unit of government (LGU) provide a higher level of engineering review to ensure a functioning system that prevents adverse impacts to groundwater?

Yes

No

PREVIOUS QUESTION and ANSWER: Is karst present on the site? - Answer: Yes

Box 23

Is BMP relocation onsite to a location without karst feasible?

Yes

No

PREVIOUS QUESTION and ANSWER: Can a local unit of government (LGU) provide a higher level of engineering review to ensure a functioning system that prevents adverse impacts to groundwater? - Answer: No

Box 24

Is Flexible Treatment Option (FTO) 2 feasible?

Yes

No

PREVIOUS QUESTION and ANSWER: Is BMP relocation onsite to a location without karst feasible? - Answer: No

Box 25

image of stop sign
You have completed the flow chart. Return to Flexible treatment options

Select Flexible treatment Option 2

  • No infiltration practices allowed
  • Explore non-infiltration volume reduction practices
  • Provide soil borings or report from a professional geologist or geotechnical engineer

Flexible Treatment Option 2 (FTO #2)

Applicant attempts to comply with the following conditions:

  1. Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
  2. Remove 60 percent of the annual total phosphorus load, and
  3. options considered and presented shall examine the merits of relocating project elements to address varying soil conditions and other constraints across the site.
Information: Previous step: It was determined that karst is present within 1000 feet of the site and the BMP cannot be reloacted so that it is more than 1000 feet from karst

You have completed the flow chart

Box 26

Is shallow groundwater or shallow bedrock present on site?

Yes

No

If you are unsure, we recommend you review the guidance for shallow groundwater in this manual. To retain your place in this flowchart, either open the shallow groundwater guidance page in a new tab (right click on the link and select Open Link in New Tab), use the back arrow after visiting the shallow groundwater guidance page, or use the Breadcrumbs at the top of the page.

PREVIOUS QUESTION and ANSWER:

  • Is karst present on the site? - Answer: No

or

  • Can a local unit of government (LGU) provide a higher level of engineering review to ensure a functioning system that prevents adverse impacts to groundwater?- Answer: Yes

or

  • Is BMP relocation onsite to a location without karst feasible? - Answer: Yes

Box 27

Conduct a detailed site investigation of shallow groundwater or shallow bedrock

Next question

PREVIOUS QUESTION and ANSWER: Is shallow groundwater or shallow bedrock present on site? - Answer: Yes

Box 28

Is there more than 3 feet of soil depth from bottom of BMP to bedrock or groundwater (more than 10 feet is preferred)?

Yes

No

PREVIOUS STEP: You were asked to conduct a detailed site investigation of shallow groundwater or shallow bedrock

Box 29

Is BMP relocation onsite to avoid shallow groundwater or shallow bedrock feasible?

Yes

No

PREVIOUS QUESTION and ANSWER: Is there more than 3 feet of soil depth from the bottom on the BMP to bedrock and groundwater (more than 10 feet is preferred)? - Answer: No

Box 30

Can the BMP be raised?

Yes

[ Box 66 No]

PREVIOUS QUESTION and ANSWER: Is BMP relocation onsite to avoid shallow groundwater and shallow bedrock feasible? - Answer: No

Box 31

image of stop sign
You have completed the flow chart. Return to Flexible treatment options

Select Flexible treatment Option 2

  • No infiltration practices allowed
  • Explore non-infiltration volume reduction practices
  • Provide soil borings or report from a professional geologist or geotechnical engineer

Flexible Treatment Option 2 (FTO #2)

Applicant attempts to comply with the following conditions:

  1. Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
  2. Remove 60 percent of the annual total phosphorus load, and
  3. options considered and presented shall examine the merits of relocating project elements to address varying soil conditions and other constraints across the site.

PREVIOUIS STEP: It was determined that shallow groundwater or shallow bedrock is present within 3 feet of the bottom of the BMP and the BMP cannot be relocated or raised in elevation to achieve a 3 foot or greater separation from bedrock or groundwater.

You have completed the flow chart

Box 32

Raise BMP enough to ensure 3 feet (preferably 10 feet) of soil between bottom of BMP and top of bedrock and groundwater

Proceed to Next Step

PREVIOUS QUESTION and ANSWER Can the BMP be raised? Answer - Yes

Box 33

Is there presence of contaminated soils and/or contaminated groundwater, or hotspot runoff?

Yes

No

PREVIOUS QUESTION and ANSWER:

  • Is shallow groundwater or shallow bedrock present on the site? - Answer: No

or

  • Is there more than 3 feet of soil depth from the bottom of the BMP to bedrock and/or groundwater? - Answer: Yes

or

  • Is BMP relocation onsite to avoid shallow bedrock and/or shallow groundwater feasible? - Answer: Yes

or

  • Can the BMP be raised? - Answer: Yes

Box 34

Can hotspot or contamination be isolated or remediated to mitigate risk of increased contamination?

Yes

No

PREVIOUS QUESTION and ANSWER: Is there presence of contaminated soils and/or contaminated groundwater, or hotspot runoff? - Answer: Yes

Box 35

image of stop sign
You have completed the flow chart. Return to Flexible treatment options

Select Flexible treatment Option 2

  • No infiltration practices allowed
  • Explore non-infiltration volume reduction practices
  • Provide Phase I or II ESAs or other documentation of potential contamination or hotspot runoff
  • Provide documentation of extent of contamination and remediation alternatives considered

Flexible Treatment Option 2 (FTO #2)

Applicant attempts to comply with the following conditions:

  1. Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
  2. Remove 60 percent of the annual total phosphorus load, and
  3. options considered and presented shall examine the merits of relocating project elements to address varying soil conditions and other constraints across the site.

PREVIOUS STEP: It was determined that contaminated soil, contaminated groundwater, or hotspot runoff is present on the site and cannot be isolated or mitigated.

You have completed the flow chart

Box 36

Are there very low infiltrating soils (less than 0.2 inches per hour) on site?

[Box 37 Yes]

[ Box 42 No]

PREVIOUS QUESTION and ANSWER:

  • Is there presence of contaminated soils, contaminated groundwater, or hotspot runoff on the site? - Answer: No

or

  • Can hotspot or contamination be isolated or remediated? - Answer: Yes

Box 37

Is BMP relocation onsite to a higher-infiltrating location feasible?

[Box 42 Yes]

[Box 38 No]

PREVIOUS QUESTION and ANSWER: Are there very low infiltrating soils (less than 0.2 inches per hour) on site? - Answer: Yes

Box 38

Can BMP be sized to drain dry within 48 hours (24 hours in locations that are tributary to trout streams)?

[ Box 42 Yes]

[Box 39 No]

PREVIOUS QUESTION and ANSWER: Is BMP relocation onsite to a higher-infiltrating location feasible? - Answer: No

Box 39

Provide soil boring or infiltration test results documenting low-infiltration soils.

[ Box 40 Next question]

PREVIOUS QUESTION and ANSWER: Can BMP be sized to drain within 48 hours (24 hours in locations that are tributary to trout streams)? Answer: No

Box 40

Box 41

Box 42

Box 43

Box 44

Box 45

Box 46

Box 47

Box 48

Box 49

Box 50

Box 51

Box 52

Box 53

Box 54

Box 55

Box 56

Box 57

Box 58

Box 59

Box 60

Box 61

Box 62

Box 63

Box 64

Box 65

PREVIOUS QUESTION and ANSWER:

  • Are there zoning and land use requirements that make the Performance Goal not feasible? - Answer: No

or

  • Is BMP relocation feasible? - Answer: Yes

Discussion

A drinking water supply management area (DWSMA) is the Minnesota Department of Health (MDH) approved surface and subsurface area surrounding a public water supply well that completely contains the scientifically calculated wellhead protection area and is managed by the entity identified in a wellhead protection plan. The boundaries of the drinking water supply management area are delineated by identifiable physical features, landmarks or political and administrative boundaries.

Links

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