Infiltration Systems Feasibility Criteria

• Soil infiltration rate, fc, > 0.5 inches/hour (requires geotechnical tests)

• Soil clay content < 20% and silt/clay content < 40%

• Cannot be located on slopes > 15% or within fill soils

• Runoff from hotspots must be pretreated before infiltration

• May be prohibited within karst regions

• Bottom should be > 4 feet above high water table or bedrock layer (requires soil borings)

• 100 feet horizontal setback from water supply well

• Maximum contributing area < 5 acres

• Horizontal Setback 25 feet down-gradient from structures

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General design considerations for infiltration systems are provided on this slide. Consideration can be given to relaxing depth to groundwater table criteria in coastal areas for non hotspot land uses.