Vertical separation

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In Ontario the vertical separation between a practice and the water tableThe upper surface of the zone of saturation, except where the surface is formed by an impermeable body.Subsurface water level which is defined by the level below which all the spaces in the soil are filled with water; The entire region below the water table is called the saturated zone. or bedrock is frequently cited as 1 meter. This comes from the

"The depth to bedrock should be greater than or equal to 1 metre below the bottom of the perforated pipe storage media to ensure adequate drainageNatural or artificial means of intercepting and removing surface or subsurface water (usually by gravity)./hydraulic potential"[1]

"If a pervious pipe system is implemented in an area where the seasonally high water tableThe upper surface of the zone of saturation, except where the surface is formed by an impermeable body.Subsurface water level which is defined by the level below which all the spaces in the soil are filled with water; The entire region below the water table is called the saturated zone. is higher than the obvert of the pipe, the pipe will drain the groundwater tableThe upper surface of the zone of saturation, except where the surface is formed by an impermeable body.. In this scenario, depending on the native soilThe natural ground material characteristic of or existing by virtue of geographic origin. characteristics and whether the trench or pipe is wrapped in geotextileFilter fabric that is installed to separate dissimilar soils and provide runoff filtration and contaminant removal benefits while maintaining a suitable rate of flow; may be used to prevent fine-textured soil from entering a coarse granular bed, or to prevent coarse granular from being compressed into underlying finer-textured soils. fabric, soil can be transported into the pipe system undermining the pipe foundation and leading to structural failure. Pervious pipe systems should not be implemented in areas where the seasonal high groundwater level is within 1 metre of the bottom of the storm sewer backfill to ensure this does not happen." [2][3][4][5][6][7] in turn citing [8]
  1. https://www.ontario.ca/document/stormwater-management-planning-and-design-manual/stormwater-management-plan-and-swmp-design
  2. Province of Ontario. “O. Reg. 332/12: BUILDING CODE,” 2018. https://www.ontario.ca/laws/regulation/120332.
  3. Karathanasis, A D, T G Mueller, B Boone, and Y L Thompson. “Nutrient Removal from Septic Effluents as Affected by Soil Thickness and Texture.” Journal of Water and Health 4, no. 2 (June 2006): 177–95. http://www.ncbi.nlm.nih.gov/pubmed/16813011.
  4. Stall, Christopher, Aziz Amoozegar, David Lindbo, Alexandria Graves, and Diana Rashash. “Transport of E. Coli in a Sandy Soil as Impacted by Depth to Water Table.” Journal of Environmental Health 76, no. 6: 92–100. Accessed October 23, 2018. http://www.ncbi.nlm.nih.gov/pubmed/24645419.
  5. RI Department of Environmental Management. “Section 5.5.1 and 5.5.4 RISDISM Guidance -- Filtering Systems: Separation to Seasonal High Groundwater Table,” 2016.
  6. Ontario. “F-6-1 Procedures to Govern Separation of Sewers and Watermains | Ontario.Ca,” 2016. https://www.ontario.ca/page/f-6-1-procedures-govern-separation-sewers-and-watermains.
  7. Rathfelder, K., and M. Wei. “Underground Stormwater Infiltration: Best Practice for Protection of Groundwater Resources in British Columbia,” 2014. http://www.env.gov.bc.ca/wsd/plan_protect_sustain/groundwater/library.html
  8. Washington St.ate Department of Ecology. “Guidance for UIC Wells That Manage Stormwater,” 2006.