Evaluation of Soil Compaction and Sealant Application for Compacted Earthen Liners

The open earthen pond system is a cost effective system for the production of microalgae and aquaculture products. Studies are required in the development of compacted earthen liners as cost-effective lining technologies to avoid negative impacts on water resources and human health. The objective of this study was to determine the effect of different levels of compaction and application of a polyacrylamide polymer as a soil sealant on the hydraulic conductivity of soil. Three soils collected from the existing pond sites were packed into aluminum cores (5 cm diameter), proctor molds (10 cm diameter) and stock pots (60 cm diameter) prior to saturated hydraulic conductivity (Ks) determination using the constant head method. A negative relationship was obtained between Ks and compaction for sandy loam, sandy clay loam and loam soils. The application of the soil sealant to compacted soil cores, proctor molds and stock pots did not decrease the Ks to the value of 1 x 10-9 m/s or lower to meet the regulatory criteria of compacted clay liners. The dry bulk density versus Ks curves indicate that sandy loam and sandy clay loam soils should be compacted to 1.82 and 1.69 g/cm3, respectively in soil cores and 2.40 and 1.59 g/cm3 in soil molds respectively to meet the regulatory criteria. The puddling experiments with sandy loam and loam soils in the stock pot also showed decreases in soil hydraulic conductivity as finer particles settle out of suspension in the soil pores. These experiments showed that sandy clay loam and loam soil can be compacted to decrease the Ks below the regularity criteria for clay liners. More experiments particularly in small ponds are needed to validate the results of the laboratory experiments