Date of Graduation

12-2014

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor/Mentor

Kristofor Brye

Committee Member

Andrew Sharpley

Second Committee Member

Wen Zhang

Third Committee Member

Esten Mason

Fourth Committee Member

Edward Gbur

Keywords

Septic Systems, Wastewater

Abstract

Nationwide, approximately 20% of all homes use an on-site septic system as a form of household wastewater treatment. Since karst features are prevalent throughout the Ozark Highlands region of Northwest Arkansas, surface and groundwater resources are susceptible to contamination. Therefore, the objectives of this study were to evaluate the effects of soil condition (i.e., wet and dry) and absorption-field-product architecture type [i.e., chamber, gravel-less-pipe (GLP), polystyrene-aggregate (PSA), and pipe-and-aggregate (PA)] on in-product solution storage and biomat thickness in a profile-limited soil, and to identify the long-term acceptance rate (LTAR) of each product. During Phase I of this study (i.e., March 13 to October 4, 2013), effluent loading rates were approximately doubled from the maximum allowable loading rate for each product. The pipe-and-tire-chip, 46-cm-wide trench pipe-and-gravel, and the 25-cm diameter GLP products had the greatest (P < 0.001), while the 31-cm-footprint and the 5.4-m-long chambers had the least (P < 0.001) amount of in-product solution storage during wet-soil conditions. Three of the 13 products appeared to reach or exceed their estimated LTAR. Averaged over soil condition and product within architecture type, the biomat thickness was greater (P < 0.001) in the PSA type than all other types, which did not differ. During Phase II of this study (i.e., October 8, 2013 to May 29, 2014), effluent loading rates were approximately quadrupled from the maximum allowable loading rates for each product. The 25-cm diameter GLP product had the greatest (P < 0.001), while the 61-cm-footprint, 5.4-m-long chamber had the least (P < 0.001) amount of in-product solution storage during Phase II. Including the three products identified during Phase I, three additional products of the 13 appeared to reach or exceed their estimated LTAR during Phase II monitoring. Similar to Phase I results, the biomat thickness was greater (P < 0.001) in the PSA architecture type than in all other types. Results of this study indicate that some alternative septic system, absorption-field products may be able to effectively handle effluent loading rates in excess of those currently allowed by the State of Arkansas, but further research will be required to confirm these interpretations.

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