| Autor: |
D. E. Radcliffe, S. D. Finch, L. T. West, E V Hufstetler |
| Rok vydání: |
2007 |
| Předmět: |
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| Zdroj: |
Eleventh Individual and Small Community Sewage Systems Conference Proceedings, 20-24 October 2007, Warwick, Rhode Island. |
| DOI: |
10.13031/2013.24012 |
| Popis: |
Understanding hydraulic properties of biomats formed at the drainfield trench-soil interface is critical for understanding long-term wastewater acceptance rates for drainfield trenches. One of the effects of biomat formation is reduction in rate of wastewater movement from the dispersal trench into the soil. Therefore, the objectives of this study were to evaluate the impact of biomats on wastewater infiltration rates through drainfield trench bottoms and sidewalls, evaluate the thickness and porosity of the biomats, and estimate biomat hydraulic conductivity. To accomplish these objectives, saturated hydraulic conductivity (Ks) was measured on undisturbed soil cores (9 cm diameter by 9 cm length) collected from the bottom and sidewall of dispersal trenches of mature onsite systems and from the adjacent natural soil. Polished blocks and thin sections prepared from undisturbed samples were used to evaluate biomat thickness and porosity. Biomat thickness determined by image analysis ranged from 4 to 8 mm with a mean of 5 mm. The Ks of the vertical and horizontally oriented natural soil samples were not statistically different and ranged from 0.03 to 41 cm d-1. The Keff of the biomat-affected soil ranged from 0.10 to 2.93 cm d-1. However, reduction in K from biomat formation was observed at only four of the seven sites because of natural variability and low soil Ks. The lack of reduction at the remaining sites was interpreted to be due to low Ks of the natural soil, natural variability in Ks, and variability in biomat development because of system design, system installation imperfections, and unequal wastewater distribution within trenches. Estimates of biomat Ks ranged from 0.01 to 0.19 cm d-1 for the four sites that had Keff less than the natural soil Ks which was 0.3 to 10% of the soil Ks. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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