Ground‐Water Remediation Using “Smart Pump and Treat”

Abstract

Established pump‐and‐treat ground‐water remediation is criticized for being too expensive and time‐consuming, especially when cleanup standards are set at very low levels, e.g., < 10 parts per billion (ppb) for volatile organic compounds (VOCs). Although other ground‐water remediation technologies are currently being examined and show intriguing promise, pump and treat remains the only dependable technology for cleanup of deep (i.e., > 50 ft below ground surface) widespread ground‐water contamination. The perceived shortcomings of pump and treat result from (1) the tendency of most contaminants to sorb to formation materials, thus retarding contaminant removal; (2) geologic complexity, which requires detailed characterization for the design of optimal extraction systems within available resources; and (3) the failure to apply dynamic well field management techniques. The alternative, “smart pump and treat” consists of (1) detailed characterization of the geology, hydrology, and chemistry; (2) use of computer‐aided data interpretation, data display, and decision support systems; (3) removal of source terms, if possible; (4) initial design for plume containment and source remediation; (5) phased installation of the well field; (6) detailed monitoring of the remediation; (7) active ongoing reevaluation of the operating well field, including redesign as appropriate (dynamic management); (8) reinjection of treated ground water to speed the flushing of contaminants; and (9) setting of appropriate cleanup levels. Use of some or all of these techniques can dramatically reduce the time required to achieve cleanup goals and thus the cost of ground‐water remediation.

Analytical study of capture zone of a horizontal well in a confined aquifer

“…Steward (1999) a horizontal well oriented perpendicularly to the direction of uniform flow required the smallest pumping rate to capture contaminated leachate. Many researchers have used numerical methods for the capture zone delineation and optimization (Ahlfeld and Sawyer, 1990;Bair and Roadcap, 1992;Ratzlaff et al, 1992;Springer and Bair, 1992;Gailey and Gorelick, 1993;Gorelick et al, 1993;Hoffman, 1993;Tiedeman and Goreick, 1993). Compared with numerical methods, analytical solutions handle problems in simpler conditions, and can directly calculate the parameters of capture zones.…”

Variation in time-to-compliance for pump-and-treat remediation of mass transfer-limited aquifers with hydraulic conductivity heterogeneity

“…P&T can be used to hydraulically contain the contaminant plume and prevent its expansion. This makes it superior to other alternative remediation techniques in handling large plumes (Hoffman 1993;Marquis and Dineen 1994).…”

Retardation of volatile organic compounds in ground water in low organic carbon sediments

“…These include; chemical heterogeneities within aquifers (Ronen et al, 1987), diffusion of contaminants into and out of heterogeneous geologic materials (Hoffman, 1993a;Wilson, 1995), sorption/desorption hysteresis Domenico and Schwartz, 1990), density induced flows (Shincariol and Schwartz, 1990; 1993; Istok and Humphrey, 1993), contaminants left in zones of stagnation and in dewatered areas within cones of depression in phreatic aquifers (Hoffman, 1993b), and the orientation of the axis of the contaminant plume with respect to the location of the extraction and monitor wells (Hoffman, 1993a). One, some, or all of these phenomena may be significant to the rate of contaminant removal during aquifer cleanup.…”