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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Agricultural Systems Research » Research » Publications at this Location » Publication #236782
Title: Predicting Saturated Hydraulic Conductivity from Percolation Test Results in Layered Silt Loam Soils

Author
item Jabro, Jalal - Jay

Submitted to: Journal of Environmental Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2009
Publication Date: 12/1/2009
Citation: Jabro, J.D. 2009. Predicting Saturated Hydraulic Conductivity from Percolation Test Results in Layered Silt Loam Soils. Journal of Environmental Health. 72(5):22-26.

Interpretive Summary: Field research was conducted on three soils classified as: a fine, mixed, mesic, Typic Hapludalf (Hagerstown silt loam); a fine-loamy, mixed, mesic, Typic Fragiudult (Monongahela silt loam); and a fine-silty, mixed, mesic, Dystric Fluventic Eutrochrept (Nolin silt loam). These soils were layered in different ways as: a silt loam Ap horizon underlain by a high clay content B horizon in the top meter, a silt loam Ap horizon underlain by a fragipan in the top meter, and an alluvial soil underlain by a gravel layer in the top meter. Three linear regression equations for the upper, middle, and lower layers were developed between the Ks values of each individual layer in all three sites and their corresponding PT. A highly significant negative correlation (P = 0.002) was found between the measurements of Ks and PT of the middle layer at depth of 50-60 cm. This indicated that the middle layer had a direct influence on the flow rate results from the percolation test hole. The lower layer of the soil profile at depth between 73-97 cm also showed a highly significant correlation (P = 0.0003) between the flow rates of the Guelph permeameter values and percolation tests indicating that the lower layer is influencing percolation test results. Significant differences were also found between Jabro equation and similar equations form other studies [Winneberger (1974) and Fritton, Ratvasky, & Petersen, (1986), respectively] at 0.01 probability level. The empirical equation derived for this study is adequate to predict Ks from PT in layered or heterogeneous soils.

Technical Abstract: The size of on-site waste disposal systems is usually determined by one or more percolation tests performed on the proposed site. The objectives of this study were to develop an empirical relationship between the saturated hydraulic conductivity (Ks) of layered soils and their percolation times (PT) in order to understand the influence of individual soil layers and compare this with the equations found by Winneberger, 1974 and Fritton et al., 1986. Field research was conducted on three soils classified as: a fine, mixed, mesic, Typic Hapludalf (Hagerstown silt loam); a fine-loamy, mixed, mesic, Typic Fragiudult (Monongahela silt loam); and a fine-silty, mixed, mesic, Dystric Fluventic Eutrochrept (Nolin silt loam). These soils were layered in different ways as: a silt loam Ap horizon underlain by a high clay content B horizon in the top meter, a silt loam Ap horizon underlain by a fragipan in the top meter, and an alluvial soil underlain by a gravel layer in the top meter. Six holes were spaced evenly in two parallel rows of three holes each approximately 50 m apart. Saturated hydraulic conductivity was measured at three different depths (layers) for each soil using a constant head well permeameter. At the end of the first layer Ks measurement, the hole was allowed to drain for 3 to 4 days. The hole was then deepened to the middle of the second layer and Ks was determined again. After completion of the second Ks measurement, the hole was allowed to drain for 3 to 4 days. Then, the hole was enlarged, using a hand post-hole auger, to approximately 0.24 m in diameter and deepened to approximately 0.52 m. After preparing and presoaking the hole, the percolation test was conducted using the standard procedure described by the Pennsylvania Department of Environmental Protection (PADEP). Three linear equations for the upper, middle, and lower layers were developed between the Ks values of each individual layer in all three sites and the corresponding PT. Significant differences were also found between Jabro equation and similar equations form other studies [Winneberger, 1974 and Fritton et al. 1986, respectively]. The empirical equation derived from this study is adequate to predict Ks from PT results in layered soils.