A two-dimensional laboratory simulator was designed and assembled to investigate removal of dense non-aqueous phase liquid (DNAPL) contaminants from ground water by water flooding and neutral buoyant co-solvent flooding. Preliminary experiments indicated that optimum DNAPL removal was achieved during water flooding for viscous-to-capillary scaling ratios between 0.00075 and 0.001. The simulator was used to investigate effects of the direction of gradient flow on DNAPL removal efficiency by neutral buoyant co-solvent flooding. Results indicated that approximately 90 percent DNAPL was removed when injection was performed either in the direction of gradient flow or against it. However, injection in the direction of gradient flow was more efficient in terms of time and total co-solvent needed. Nevertheless, during injection in the direction of the flow more contamination occurred downstream due to dispersion. Results also indicated that size of the plume does not play an important role in the recovery efficiency of this system / acase@tulane.edu

A pilot-scale test rig was constructed to simulate intrusion behavior associated with hydraulic transients. Initial tests were conducted using a high-speed datalogger to verify low/negative pressures. Results indicated negative pressures (maximum -12 psi) for 3 to 5 seconds following sudden valve closures. With steady state flow, three orifice diameters (1/8 ″, ¼″ and ½″ ) were overlaid with 3 or 4.5 feet of head to simulate cracks or leak points in a water distribution system. Based on volumetric measurements, average intrusion volumes associated with transients ranged from 47.3 to 550.2 mL. Based on chemical tracer (cesium) measurements, average intrusion volumes ranged from 11.4 to 71.2 mL for 1/8″ and ¼ ″ orifices, respectively. Differences were attributed primarily to dilution of cesium in the test rig. Results also were compared to theoretical and computer model predictions. Findings from this research demonstrate that external water and pathogens potentially can intrude into pipelines during transient events / acase@tulane.edu