Slow rate (SR)
Soil aquifer treatment (SAT) or rapid infiltration (RI)
Land application Composting, freezing, vermistabilization, or reed beds
Sandy loams to clay loams: >0.15 to <15 cm/hr permeability preferred, bedrock and groundwater >1.5 m, slopes <20%, agricultural sites <12%
Sands to sandy loams: 5 to 50 cm/hr permeability, bedrock and groundwater >5 m preferred, >3 m necessary, slopes <10%; sites with slopes that require significant backfill for basin construction should be avoided; preferred sites are near surface waters where subsurface flow may discharge over non-drinking-water aquifers Slowly permeable soils, slopes 0 to 6%, out of flood plain, no bedrock or groundwater within excavation depth
Generally the same as for agricultural or forested SR systems Usually sited on the same site as the wastewater treatment plant; all three require impermeable barriers to protect groundwater; freezing and reed beds also require underdrains for the percolate
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