Home > Online Store

Online Store

 Hydraulic Loading Rate and Infiltrative Surface Architecture Effects on Septic Tank Effluent Treatment During Soil Infiltration
Kathryn S. Lowe, Robert. L. Siegrist, and Kyle N. Tackett
Item Number: NRL2006AC-21
Shipping Weight: 0lbs. 0oz.
Price: $20.00
Decentralized wastewater management involving onsite wastewater systems (OWS) is a necessary and appropriate component of a sustainable wastewater infrastructure. To fulfill this role, OWS must provide reliable treatment to a degree that protects public health and water quality. During soil treatment, development of a biozone can beneficially impact treatment by altering the hydraulic and purification processes. To evaluate the soil treatment performance of applied wastewater (septic tank effluent) and aid in OWS design, a field experiment was initiated in Spring 2003 with continued operation and monitoring for over three years. A replicated factorial design was employed to evaluate three infiltrative surface architectures (stone, open, and synthetic) and two design hydraulic loading rates (4 and 8 cm/d) in native sandy loam soils at the Mines Park Test Site located on the campus of the Colorado School of Mines in Golden, Colorado. Performance monitoring revealed that infiltrative surface architecture and the hydraulic loading rate influenced the rate and extent of loss in hydraulic capacity through their impacts on the development of the biozone. Infiltration rates, measured after test cells had effluent ponding of ≥20 cm for 3 consecutive weeks, had the following trends summarized as: open > stone > synthetic, and; 8 cm/d design HLR > 4 cm/d design HLR. Treatment of domestic septic tank effluent during infiltration and percolation through the sandy loam soil was very high. While there was no observed difference in the treatment performance based on infiltrative surface architecture or level of ponding, an increase in the vadose zone depth did provide a somewhat increased removal of carbon, total nitrogen or phosphorus.