Aquifer remediation

Microemulsions became well known from about 1975 to 1980 because of their use ia "micellar-polymer" enhanced oil recovery (EOR) (35). This technology exploits the ultralow iaterfacial tensions that exist among top, microemulsion, and bottom phases to remove large amounts of petroleum from porous rocks, that would be unrecoverable by conventional technologies (36,37). Siace about 1990, iaterest ia the use of this property of microemulsions has shifted to the recovery of chloriaated compounds and other iadustrial solveats from shallow aquifers. The latter appHcatioa (15) is sometimes called surfactant-enhanced aquifer remediation (SEAR). 

The MCL for TCE (5 pg/L) has been determined to be a relevant and appropriate remediation level for the contaminated groundwater at this site because the groundwater is used as a source for drinking water. Based on the site-specific risk assessment, the MCL has been determined to be sufficiently protective as the aquifer remediation goal. 

These results differ sharply from the behavior predicted by the distribution coefficient (K( ) approach. This approach, despite being broadly acknowledged as too simplistic to describe the behavior of heavy metals, is nonetheless the sorption model most commonly applied in studying aquifer remediation. 

Nyer, E. K. and Skladany, G. J., 1989, Relating the Physical and Chemical Properties of Petroleum Hydrocarbons to Soil and Aquifer Remediation Ground Water Monitoring Review, Winter, pp. 54—60. 

A traditional approach to aquifer remediation is to remove the contaminated water by pumping, treating the water at the surface, and then either discharging it or reinjecting it back into the aquifer. When the recovery wells are properly located, this approach has the advantage of creating a capture area which contains and prevents the contamination from migrating. 

Use of these equations to predict future production from a recovery project is described by the following example. An abandoned refinery property is being dismantled and the underlying aquifer remediated. Substantial LNAPL product accumulations occurred overlying the fine silty sand aquifer. Preliminary investigation indicated that a four-well system would effectively remove most of the product within a reasonable time at a modest cost. The production rate over time is illustrated in Figure 11.4. Peak production occurred on day 78 of operation, then declined. Final measurement occurred on day 141. 

T0213 Duke Engineering Services, Inc., Chemically Enhanced Solubilization for Aquifer Remediation (CESAR)... 

This technology, along with similar technologies such as surfactant flushing, was originally developed in the petroleum industry to improve hydrocarbon recovery. Its use in environmental apphcations such as aquifer remediation is relatively new, with most laboratory and field trials having been carried out during the past 8 years. 

The CESAR (chemically enhanced solubilization for aquifer remediation) technology is a surfactant-enhanced pump-and-treat technology that remediates an aquifer by treating organic contaminants with a chemical surfactant solution. The surfactant solubilizes the contaminants, thus making them more readily transportable to the extraction weUs. This technology is currently commercially available. 

Aksoy, A., and Culver, T. B. (2000). "Effect of sorption assumptions on the optimization of aquifer remediation designs." Ground Water, 38(2), 200-208. 

Harvey, C. F., Haggerty, R., and Gorelick, S. M (1994). "Aquifer remediation A method for estimating mass transfer rate coefficients and an evaluation of pulsed pumping." Water Resour. Res., 30(7), 1979-1991. 

McKinney, D. C., and Lin, M. D. (1995). "Approximate mixed-integer nonlinear programming methods for optimal aquifer remediation design." Water Resour. Res., 31(3), 731-740. 

Rabideau, A. J., and Miller, C. T. (1994). "Two-dimensional modeling of aquifer remediation influenced by sorption non-equilibrium and hydraulic conductivity heterogeneity." Water Resour. Res., 30(5), 1457-1470. 

Key words surfactant-enhanced aquifer remediation surfactant sorption distribution... 

Fountain, J.C. (1997). The role of field trials in development and feasibility assessment of surfactant-enhanced aquifer remediation. Water Environ. Res., 69, 188-195. 

Fountain, J.C., Starr, R.C., Middleton, T., Beikirch, M., Taylor, C., and Hodge, D. (1996). A controlled field test of surfactant-enhanced aquifer remediation. Ground Water, 34, 910-916. 

Shook G.M., Pope, G.A., and Kostarelos, K. (1998). Prediction and minimization ofvertical migration of DNAPLs using surfactant enhanced aquifer remediation at neutral... 

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