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Nale-IT® and Microsolv® are registered trademarks of SPL Control, L.L.C., Elmore City, Oklahoma Tel: (580) 788-2187
dikes 2-3 feet (60-90 cm) in height, are built to limit potential runoff and prevent spillage. Diversionary trenches are typically dug adjacent to the dikes to divert up gradient surface runoff away from the treatment unit. When required, a “clean” clay liner is placed on the bio-cell floor and draped over the perimeter dikes. The liner is compacted to create a seal to prevent leaching to the underlying receiving soil. A 12 in (30 cm) sand layer is typically placed above the liner to protect it against damage from treatment tilling practices.
Prior to construction, the receiving soil is sampled on a predetermined grid pattern. The recommended sampling depth is 14 in (35 cm) below grade. These samples are composited to one (1) sample and delivered to a certified laboratory for analysis of soil characteristics and residual waste contaminants. Composite samples of the clay liner, soil amendments and waste materials are also collected and analysed to establish baseline conditions.
Contaminated material is transferred to the bio-cell and spread to a uniform thickness of 6-8 inches (15-20 cm). A native soil amendment is incorporated into the waste to introduce the indigenous microorganisms needed for bio-remediation. The mix is then treated topically with Nale-IT® (Microsolv®) at a ratio of one (1) part chemical agent to twenty (20) parts water. Tilling is conducted until a homogeneous mix is attained to assure adequate contact of the microorganisms with the waste and to establish optimum moisture content and dissolved oxygen levels. Operating parameters are monitored and adjusted by additional water application and tillage to keep moisture content within a range of 30-40%, pH near neutral and dissolved oxygen at levels greater than 2.0 mg/l.
Composite sampling of the waste is conducted on a predetermined schedule to monitor petroleum hydrocarbon degradation rates, microbial populations, and mix characteristics. After the initial application tilling is performed, on an as needed basis, to promote aeration for an oxygen supply and to maintain the homogeneous mix. This maintenance program is continued until the desired cleanup goals are achieved.
Upon completion of treatment, the receiving soil is sampled again to document that remedial actions did not cause leaching. It is recommended that “post-treatment” receiving soil samples be collected at the same locations as the “pre-treated” receiving soil samples to reduce variance in laboratory results due to random sampling.
Bio-cells are designed to specifications for the treatment of contaminated material in lifts no deeper than 6-8 in (15-20 cm). If available land is limited, treatment can be completed in multiple lifts. On land surfaces that exhibit a significant slope, local burrow is placed on the downhill side to assure the
bio-cell floor is level. Perimeter