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Minnesota Stormwater Manual

Difference between revisions of "Stormwater infiltration and contaminated soils and groundwater"

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[[file:Contaminated soil 1.png|300px|thumb|alt=schematic of contaminated soil|<font size=3>Schematic for site where infiltration may be feasible. Although the groundwater mound does not extend into the contamination, it needs to be determined if water will infiltrate through the contaminated soil and transport pollutants at levels of concern. Source:CDM Smith.  For a discussion of considerations at sites with on- or off-site contamination, see [[Overview of considerations for sites with on-site and off-site contamination|this page]].</font size>]]
 
[[file:Contaminated soil 1.png|300px|thumb|alt=schematic of contaminated soil|<font size=3>Schematic for site where infiltration may be feasible. Although the groundwater mound does not extend into the contamination, it needs to be determined if water will infiltrate through the contaminated soil and transport pollutants at levels of concern. Source:CDM Smith.  For a discussion of considerations at sites with on- or off-site contamination, see [[Overview of considerations for sites with on-site and off-site contamination|this page]].</font size>]]
  
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{{alert| The [http://stormwater.pca.state.mn.us/index.php/III._STORMWATER_DISCHARGE_DESIGN_REQUIREMENTS#III.D._PERMANENT_STORMWATER_MANAGEMENT_SYSTEM Construction Stormwater General permit prohibits] the use of infiltration BMPs in areas where high levels of contaminants in soil or groundwater will be mobilized by the infiltrating stormwater|alert-danger}}
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{{alert| The [http://stormwater.pca.state.mn.us/index.php/III._STORMWATER_DISCHARGE_DESIGN_REQUIREMENTS#III.D._PERMANENT_STORMWATER_MANAGEMENT_SYSTEM Construction Stormwater General permit prohibits] permittees from constructing infiltration systems where infiltrating stormwater may mobilize high levels of contaminants in soil or groundwater. Permittees must either complete the [https://stormwater.pca.state.mn.us/index.php?title=File:Contamination_screening_checklist_for_stormwater_infiltration_July_2016.xlsx MPCA's contamination screening checklist] or conduct their own assessment to determine the suitability for infiltration. Permittees must retain the checklist or assessment with the SWPPP.
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For more information and to access the MPCA's "contamination screening checklist" [https://stormwater.pca.state.mn.us/index.php?title=Stormwater_Infiltration_and_soil/groundwater_contamination:_A_guide_to_the_Construction_Stormwater_Permit_requirements see the Minnesota Stormwater Manual].|alert-danger}}
  
 
Managing stormwater at sites with contaminated soils or groundwater is challenging because the infiltrated runoff has the potential to transport contaminants in the soil to the groundwater or mobilize contaminants in the groundwater. Stormwater at contaminated sites can be managed by surface capture and treatment, or as infiltration by avoiding contact between runoff and contaminated soils and groundwater. Surface capture includes [http://stormwater.pca.state.mn.us/index.php/Stormwater_filtration_Best_Management_Practices filtration] and [http://stormwater.pca.state.mn.us/index.php/Stormwater_sedimentation_Best_Management_Practices sedimentation] practices. When considering surface capture and treatment of runoff at contaminated sites, the surface capture treatment system will usually need an impermeable barrier to prevent infiltration and potential mobilization of contaminates in soil or groundwater. When considering [http://stormwater.pca.state.mn.us/index.php/Stormwater_infiltration_Best_Management_Practices stormwater infiltration] at contaminated sites, it is essential to develop management options to ensure contaminants are not mobilized. To accomplish this, a project proposer must understand site conditions (e.g. soils, hydrogeology, land use), the nature and extent of contamination (i.e. site conceptual model), and applicable regulations. The following pages provide information on these topics, including case studies and links to additional information and guidance.
 
Managing stormwater at sites with contaminated soils or groundwater is challenging because the infiltrated runoff has the potential to transport contaminants in the soil to the groundwater or mobilize contaminants in the groundwater. Stormwater at contaminated sites can be managed by surface capture and treatment, or as infiltration by avoiding contact between runoff and contaminated soils and groundwater. Surface capture includes [http://stormwater.pca.state.mn.us/index.php/Stormwater_filtration_Best_Management_Practices filtration] and [http://stormwater.pca.state.mn.us/index.php/Stormwater_sedimentation_Best_Management_Practices sedimentation] practices. When considering surface capture and treatment of runoff at contaminated sites, the surface capture treatment system will usually need an impermeable barrier to prevent infiltration and potential mobilization of contaminates in soil or groundwater. When considering [http://stormwater.pca.state.mn.us/index.php/Stormwater_infiltration_Best_Management_Practices stormwater infiltration] at contaminated sites, it is essential to develop management options to ensure contaminants are not mobilized. To accomplish this, a project proposer must understand site conditions (e.g. soils, hydrogeology, land use), the nature and extent of contamination (i.e. site conceptual model), and applicable regulations. The following pages provide information on these topics, including case studies and links to additional information and guidance.

Revision as of 17:42, 17 August 2018

Information: This page and pages that link to this page are in development.
schematic of contaminated site
Schematic for site where infiltration is not feasible. Note impermeable liner and discharge from underdrain to storm sewer system. For a discussion of considerations at sites with on- or off-site contamination, see this page.
schematic of contaminated soil
Schematic for site where infiltration is feasible. Note that contaminated soils are overlain by an impermeable surface and the groundwater mound does not extend into the contamination. Source:CDM Smith.
schematic of contaminated soil
Schematic for site where infiltration may be feasible. Although the groundwater mound does not extend into the contamination, it needs to be determined if water will infiltrate through the contaminated soil and transport pollutants at levels of concern. Source:CDM Smith. For a discussion of considerations at sites with on- or off-site contamination, see this page.
Information: alert-danger

Managing stormwater at sites with contaminated soils or groundwater is challenging because the infiltrated runoff has the potential to transport contaminants in the soil to the groundwater or mobilize contaminants in the groundwater. Stormwater at contaminated sites can be managed by surface capture and treatment, or as infiltration by avoiding contact between runoff and contaminated soils and groundwater. Surface capture includes filtration and sedimentation practices. When considering surface capture and treatment of runoff at contaminated sites, the surface capture treatment system will usually need an impermeable barrier to prevent infiltration and potential mobilization of contaminates in soil or groundwater. When considering stormwater infiltration at contaminated sites, it is essential to develop management options to ensure contaminants are not mobilized. To accomplish this, a project proposer must understand site conditions (e.g. soils, hydrogeology, land use), the nature and extent of contamination (i.e. site conceptual model), and applicable regulations. The following pages provide information on these topics, including case studies and links to additional information and guidance.



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