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USING SOIL SURVEYS TO PREDICT THE TYPE OF ONSITE WASTEWATER TREATMENT SYSTEM
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.orgCitation: Pp. 116-124 in On-Site Wastewater Treatment, Proc. Ninth Natl. Symp. on Individual and Small Community Sewage Systems (11-14 March 2001, Fort Worth, Texas, USA), ed. K. Mancl., St. Joseph, Mich. ASAE 701P0009.(doi:10.13031/2013.6022)
Authors: A.C. Engebretson, E.J. Tyler
Keywords: Land use, Soils, Wastewater disposal
Limitation tables published in county soil survey reports for on-site wastewater treatment systems (OWTS) are for infiltration components installed 60 cm below the ground surface with 120 cm of unsaturated, unconsolidated permeable soil beneath the infiltrative surface. Users of limitation tables frequently apply the information to designs different than those used to develop the limitation ratings. The purpose of this research was to establish how well a soil survey could predict the design of OWTS. The location of 181 randomly selected OWTS was determined within a meter using a Sokkia Global Positioning System (GPS). Because locations were not recorded for unsuitable sites according to regulations, the probability of obtaining a permit by soil map units could not be determined. However, soils with systems rated as slight according to the limitations ratings were 89% in-ground systems and 11% above-grade, including mounds and at-grades. For soils rated as very severe, 22% were in-ground and 78% above-grade. Data were evaluated using chi-squared analysis and 95% confi-dence intervals. The limitation ratings can be used to interpret in-ground system use. Since severe and very severe ratings are considered unsuitable for systems, it is generally believed no system can be used. However, above-grade systems are possible. A system incorporating all technical designs could reduce the misconception of the users. The limitation ratings predict the use of in-ground systems but are not designed to account for above-grade systems.(Download PDF) (Export to EndNotes)