MIDS design sequence flow chart
Contents
- 1 Box 1
- 2 Box 2
- 3 Box 3
- 4 Box 4
- 5 Box 5
- 6 Box 6
- 7 Box 7
- 8 Box 8
- 9 Box 9
- 10 Box 10
- 11 Box 11
- 12 Box 12
- 13 Box 13
- 14 Box 14
- 15 Box 15
- 16 Box 16
- 17 Box 17
- 18 Box 18
- 19 Box 19
- 20 Box 20
- 21 Box 21
- 22 Box 22
- 23 Box 23
- 24 Box 24
- 25 Box 25
- 26 Box 26
- 27 Box 27
- 28 Box 28
- 29 Box 29
- 30 Box 30
- 31 Box 31
- 32 Box 32
- 33 Box 33
- 34 Box 34
- 35 Box 35
- 36 Box 36
- 37 Box 37
- 38 Box 38
- 39 Box 39
- 40 Box 40
- 41 Box 41
- 42 Box 42
- 43 Box 43
- 44 Box 44
- 45 Box 45
- 46 Box 46
- 47 Box 47
- 48 Box 48
- 49 Box 49
- 50 Box 50
- 51 Box 51
- 52 Box 52
- 53 Box 53
- 54 Box 54
- 55 Box 55
- 56 Box 56
- 57 Box 57
- 58 Box 58
- 59 Box 59
- 60 Box 60
- 61 Box 61
- 62 Box 62
- 63 Box 63
- 64 Box 64
- 65 Box 65
- 66 Box 66
Box 1
Did you gather the site information necessary to proceed through the flow chart?
Box 2
Prior to using the flow chart, gather the following preliminary information.
- Conduct site review
- Define performance goal
Conduct site review
- Aerial photos and topographic maps
- County soil surveys and other soil information as available
- County Geologic Atlas
- Local groundwater levels
- DWSMA and Wellhead Protection maps
- FEMA and local floodplain maps
- Soil borings and site survey
- MPCA listing of potentially contaminated sites
- Phase 1 and 2 Environmental Site Assessments
- TMDLs and local water quality standards
- Wetland delineations, MNRAM assessments, and wetland classifications
- Proposed conditions, conceptual/preliminary site design
- Local zoning and land use requirements/ordinances, including stormwater rate control requirements
- Communication with local landowners, LGU, or others knowledgeable about the site
- Site inspection
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
Links
- Performance goals for new development, re-development and linear projects
- For background and derivation of the performance goals, see technical documents and presentations on the MIDS website. We provide links to some of these documents and presentations below.
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
Is the project linear?
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?
Box 8
Is Flexible Treatment Option (FTO) 2 feasible?
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
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:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- 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
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:
- Locations that yield benefits to the same receiving water that receives runoff from the original construction activity.
- Locations within the same Department of Natural Resources (DNR) catachment area as the original construction activity.
- Locations in the next adjacent DNR catchment area up-stream.
- 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?
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
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?
PREVIOUS QUESTION and ANSWER: Is BMP relocation feasible - Answer: No
Flexible Treatment Option 1 (FTO #1)
Applicant attempts to comply with the following conditions:
- Achieve at least 0.55 inch volume reduction goal, and
- Remove 75 percent of the annual total phosphorus load, and
- 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?
==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:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- 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?
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
- The Minnesota Department of Health maintains maps, shapefiles and other information on source water protection in Minnesota, including maps of Drinking Water Supply Management Areas (DWSMAs).
- Minnesota Department of Health Source Water Protection main page
- http://water.epa.gov/infrastructure/drinkingwater/sourcewater/protection/index.cfm United States Environmental Protection Agency] Source Water protection page
- Evaluating Proposed Stormwater Infiltration Projects in Vulnerable Wellhead Protection Areas
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?
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?
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?
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?
PREVIOUS QUESTION and ANSWER: Is BMP relocation feasible? - Answer: No
Box 20
Is Flexible Treatment Option (FTO) 2 feasible?
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:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- 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?
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?
PREVIOUS QUESTION and ANSWER: Is karst present on the site? - Answer: Yes
Box 23
Is BMP relocation onsite to a location without karst feasible?
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?
PREVIOUS QUESTION and ANSWER: Is BMP relocation onsite to a location without karst feasible? - Answer: No
Box 25
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:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- options considered and presented shall examine the merits of relocating project elements to address varying soil conditions and other constraints across the site.
You have completed the flow chart
Box 26
Is shallow groundwater or shallow bedrock present on site?
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
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)?
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?
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?
PREVIOUS QUESTION and ANSWER: Is BMP relocation onsite to avoid shallow groundwater and shallow bedrock feasible? - Answer: No
Box 31
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:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- 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
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?
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?
PREVIOUS QUESTION and ANSWER: Is there presence of contaminated soils and/or contaminated groundwater, or hotspot runoff? - Answer: Yes
Box 35
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:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- 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?
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?
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)?
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.
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
Is Flexible Treatment Alternative No 1 feasible, allowing BMP to drain in 48 hours?
PREVIOUS STEP: You were asked to provide soil boring or infiltration test results documenting low-infiltration soils.
Box 41
Select Flexible treatment Option 2
- No infiltration practices allowed
- Explore non-infiltration volume reduction practices
- Provide soil boring or infiltration test results documenting low-infiltration soils
Flexible Treatment Option 2 (FTO #2)
Applicant attempts to comply with the following conditions:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- 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 soils on the site have an infiltration rate of less than 0.2 inches per hour, the BMP cannot be relocated to areas with a higher infiltration rate, and the BMP cannot be sized to drain within 48 hours (24 hours in locations that are tributary to trout streams)
You have completed the flow chart
Box 42
Are there very high infiltrating soils (more than 8 inches per hour) on site?
PREVIOUS QUESTION and ANSWER:
- Are there very low infiltrating soils (less than 0.2 inches per hour) present on site? - Answer: No
or
- Is BMP relocation onsite to a higher-infiltrating location feasible? - Answer: Yes
or
- Can BMP be sized to drain dry within 48 hours (24 hours in locations that are tributary to trout streams)? - Answer: Yes
Box 43
Is BMP relocation onsite to a lower-infiltrating location feasible?
PREVIOUS QUESTION and ANSWER: Are there very high infiltrating soils (more than 8 inches per hour) on site? - Answer: Yes
Box 44
Can subgrade be modified to slow the rate of infiltration to less than 8 inches per hour?
PREVIOUS QUESTION and ANSWER: Is BMP relocation onsite to a lower-infiltrating location feasible? - Answer: No
Box 45
Select Flexible treatment Option 2
- No infiltration practices allowed
- Explore non-infiltration volume reduction practices
- Provide soil boring or infiltration test results documenting high-infiltration soils
Flexible Treatment Option 2 (FTO #2)
Applicant attempts to comply with the following conditions:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- options considered and presented shall examine the merits of relocating project elements to address varying soil conditions and other constraints across the site.
PREVIOUS QUESTION and ANSWER
You have completed the flow chart
Box 46
Are there adverse surface water hydrologic impacts from infiltration practices (e.g. impacting perched wetland)?
PREVIOUS QUESTION and ANSWER: Are there very high infiltrating soils (greater than 8 inches per hour) present on site)? - Answer: No or
- Is BMP relocation onsite to a lower infiltrating location feasible? - Answer: Yes
or
- Can subgrade be modified to slow the rate of infiltration? - Answer: Yes
Box 47
Can the BMP be relocated to avoid adverse hydrologic impacts?
PREVIOUS QUESTION and ANSWER: Are there adverse surface water hydrologic impacts from infiltration practices (e.g. impacting perched wetland)? - Answer: Yes
Box 48
Would BMPs accomodating Flexible treatment option 1 avoid adverse hydrologic impacts?
PREVIOUS QUESTION and ANSWER: Can the BMP be relocated to avoid adverse hydrologic impacts? - Answer: No
Box 49
Select FTO Alternative No. 2
- Maximize infiltration BMPs to treat up to the 0.55 inch goal, if possible
- Explore non-infiltration volume reduction practices
- provide report documenting potential hydrologic impacts from infiltration on the site, prepared by a registered engineer, hydrologist, or wetland specialist
Flexible Treatment Option 2 (FTO #2)
Applicant attempts to comply with the following conditions:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- options considered and presented shall examine the merits of relocating project elements to address varying soil conditions and other constraints across the site.
You have completed the flow chart
Box 50
Select FTO Alternative No. 1
Flexible Treatment Option 1 (FTO #1)
Applicant attempts to comply with the following conditions:
- Achieve at least 0.55 inch volume reduction goal, and
- Remove 75 percent of the annual total phosphorus load, and
- Options considered and presented shall examine the merits of reloacting project elements to address varying soil conditions and other constraints across the site
Additional considerations
- Maximize infiltration BMPs to treat more than 0.55 inch goal if possible
- If Flexible Treatment Option 1 was determined based on presence of low infiltrating soils, provide soil boring or infiltration test results documenting low-infiltrating soils
- if Flexible Treatment Option 1 was determined based on presence of adverse surface water hydrologic impacts from infiltration practices, provide a report that documents the potential hydrologic impacts from infiltration on the site, prepared by a registered engineer, hydrologist, or wetlands specialist.
You have completed the flow chart
Box 51
Complete design using the following performance goals
- New development projects
- 1.1 inches from new impervious surfaces
- Redevelopment projects - 1.1 inches from new impervious surfaces
- Linear projects
- 0.55 inches of runoff from the new and fully reconstructed impervious surfaces
- 1.1 inches of runoff from the net increase in impervious area
You have completed the flow chart
Box 52
Do the following conditions apply?
- Zoning and land use requirements make Flexible Treatment Option 2 not feasible
and
- The BMP cannot be relocated to accommodate zoning and land use restrictions
Box 53
Do the following conditions apply?
- There are existing or proposed structures or infrastructure that make Flexible Treatment Option 2 not feasible
and
- BMP relocation is not feasible
PREVIOUS QUESTION and ANSWER: You determined that Flexible Treatment Option 2 is feasible and there are no limitations resulting from zoning and land use requirements.
Box 54
Do any of the following conditions apply? (NOTE: If any condition applies, you do not need to answer the remaining questions.)
- The site is located within a DWSMA, wellhead protection area, or within 200 feet of a drinking water well, and infiltration is not allowed by the LGU
- Karst is present within 1000 feet of the site and the BMP cannot be relocated so that it is more than 1000 feet from karst
- 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
- Contaminated soil, contaminated groundwater, or hotspot runoff is present on the site and cannot be isolated or mitigated
- Soils on the site have an infiltration rate of less than 0.2 inches per hour, the BMP cannot be relocated to areas with a higher infiltration rate, and the BMP cannot be sized to drain within 48 hours (24 hours in locations that are tributary to trout streams)
- Soils on the site have an infiltration rate greater than 8 inches per hour, the BMP cannot be relocated to an area with an infiltration rate lower than 8 inches per hour, or the subgrade cannot be modified to slow the infiltration rate to less than 8 inches per hour
Box 55
Do the following conditions apply?
- There are existing or proposed structures or infrastructure that make FTO 2 not feasible
and
- BMP relocation is not feasible
PREVIOUS QUESTION and ANSWER You determined that Flexible Treatment Option 2 is feasible and there are no limitations resulting from zoning and land use requirements.
Box 56
Select Flexible Treatment Option (FTO) 2
- No infiltration practices allowed
- Explore non-infiltration volume reduction practices
- Provide DWSMA or well location map
Flexible Treatment Option 2 (FTO #2)
Applicant attempts to comply with the following conditions:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- 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 located within a DWSMA, wellhead protection area or within 200 feet of a drinking water well and infiltration is not allowed by the LGU.
You have completed the flow chart
Box 57
Do any of the following conditions apply? (NOTE: If any condition applies, you do not need to answer the remaining questions.)
- The site is located within a DWSMA, wellhead protection area or within 200 feet of a drinking water well and Can a Local Government Unit (LGU) provide a higher level of engineering review to ensure a functioning system that prevents adverse impacts to groundwater.
- Karst is present within 1000 feet up-gradient or 100 feet down-gradient of the site, a local unit of government cannot provide a higher level of engineering review to ensure a functioning system that prevents adverse impacts to groundwater, and the BMP cannot be reloacted so that it is more than 1000 feet from karst.
- 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.
- Contaminated soil, contaminated groundwater, or hotspot runoff is present on the site and cannot be isolated or mitigated
- Soils on the site have an infiltration rate of less than 0.2 inches per hour, the BMP cannot be relocated to areas with a higher infiltration rate, and the BMP cannot be sized to drain within 48 hours (24 hours in locations that are tributary to trout streams)
- Soils on the site have an infiltration rate greater than 8 inches per hour, the BMP cannot be relocated to an area with an infiltration rate lower than 8 inches per hour, or the subgrade cannot be modified to slow the infiltration rate to less than 8 inches per hour
PREVIOUS STEP: You determined that flexible Treatment option 1 is feasible.
Box 58
Is Flexible Treatment Option 2 feasible?
Flexible Treatment Option 2 (FTO #2)
Applicant attempts to comply with the following conditions:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- options considered and presented shall examine the merits of relocating project elements to address varying soil conditions and other constraints across the site.
Box 59
Do the following conditions apply?
- There are very high infiltrating soils (more than 8 inches per hour) on the site;
- BMP relocation to an area with lower infiltration rates is not feasible; and
- The subgrade cannot be modified to slow the rate to less than 8 inches per hour.
PREVIOUS QUESTION and ANSWER: Is Flexible Treatment Alternative No 1 feasible, allowing BMP to drain in 48 hours? - Answer: Yes
Box 60
Do the following conditions apply?
- There are adverse hydrologic impacts from infiltration practices
- The BMP cannot be relocated to avoid adverse hydrologic impacts; and
- BMPs accomodating FTO 1 would avoid adverse hydrologic impacts
Box 61
Are there existing or proposed structures or infrastructure that make Flexible Treatment Option 1 not feasible?
PREVIOUS STEP: You determined that flexible Treatment option 1 is feasible.
Box 62
Do any of the following conditions apply? (NOTE: If any condition applies, you do not need to answer the remaining questions.)
- The site is located within a DWSMA, wellhead protection area, or within 200 feet of a drinking water well, and a Local Government Unit (LGU) can provide a higher level of engineering review to ensure a functioning system that prevents adverse impacts to groundwater.
- Karst is present within 1000 feet up-gradient or 100 feet down-gradient of the site, a local unit of government cannot provide a higher level of engineering review to ensure a functioning system that prevents adverse impacts to groundwater, and the BMP cannot be relocated so that it is more than 1000 feet from karst.
- 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.
- Contaminated soil, contaminated groundwater, or hotspot runoff is present on the site and cannot be isolated or mitigated
- Soils on the site have an infiltration rate of less than 0.2 inches per hour, the BMP cannot be relocated to areas with a higher infiltration rate, and the BMP cannot be sized to drain within 48 hours (24 hours in locations that are tributary to trout streams)
- Soils on the site have an infiltration rate greater than 8 inches per hour, the BMP cannot be relocated to an area with an infiltration rate lower than 8 inches per hour, or the subgrade cannot be modified to slow the infiltration rate to less than 8 inches per hour
- Soils on the site have an infiltration rate of less than 0.2 inches per hour, the BMP cannot be relocated to areas with an infiltration rate greater than 0.2 inches per hour, the BMP cannot be sized to drain within 48 hours (24 hours in locations that are tributary to trout streams), and Flexible Treatment Option 1 is feasible.
PREVIOUS STEP: You determined that Flexible Treatment Option 1 is feasible.
Box 63
Do the following conditions apply?
- There are adverse hydrologic impacts from infiltration practices; and
- The BMP cannot be relocated to avoid adverse hydrologic impacts
Box 64
Select Flexible Treatment Option (FTO) 2
- Provide regulations and/or cost estimates documenting infeasibility of meeting the original Performance goal
Flexible Treatment Option 2 (FTO #2)
Applicant attempts to comply with the following conditions:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- 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
- there are no site conditions that prevent infiltration and there are no adverse surface water hydrologic impacts from infiltration practices, but
- there are zoning and land use requirements that make the Performance Goal not feasible and BMP relocation is not feasible; or
- there are existing or proposed structures or infrastructure that make the Performance Goal not feasible and BMP relocation is not feasible.
You have completed the flow chart
Box 65
Select Flexible Treatment Option (FTO) 2
- Provide regulations and/or cost estimates documenting infeasibility of meeting the original Performance goal;
- Maximize infiltration BMPs to treat up to the 0.55 inch goal, if possible;
- Explore non-infiltration volume reduction practices; and
- Provide report documenting potential hydrologic impacts from infiltration on the site, prepared by a registered engineer, hydrologist, or wetland specialist
Flexible Treatment Option 2 (FTO #2)
Applicant attempts to comply with the following conditions:
- Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and
- Remove 60 percent of the annual total phosphorus load, and
- 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
- there are no site conditions that prevent infiltration but
- there are adverse surface water hydrologic impacts from infiltration practices and BMP relocation is not feasible; and
- there are zoning and land use requirements that make the Performance Goal not feasible and BMP relocation is not feasible; or
- there are existing or proposed structures or infrastructure that make the Performance Goal not feasible and BMP relocation is not feasible.
You have completed the flow chart
Box 66
Is Flexible Treatment Option (FTO) 2 feasible?
PREVIOUS QUESTION and ANSWER: Can the BMP be raised? - Answer: No