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Full-Text Articles in Physical Sciences and Mathematics
The Hazardous Waste Land, Jerry L. Anderson
The Hazardous Waste Land, Jerry L. Anderson
Jerry L. Anderson
This article was one of the first comprehensive critiques of the Superfund remediation and liability system. The article addresses systemic problems with the CERCLA mechanism that result in inequity and slow the pace of cleanups.
Field Experiments In A Fractured Clay Till: 2. Solute And Colloid Transport, Larry Mckay, Robert W. Gillham, John A. Cherry
Field Experiments In A Fractured Clay Till: 2. Solute And Colloid Transport, Larry Mckay, Robert W. Gillham, John A. Cherry
Larry McKay
A field tracer experiment was conducted in a lateral flow field in the weathered and highly fractured upper 6 m of a 40-m-thick clay-rich till plain in southwestern Ontario. In the upper 3 m where fractures are closely spaced (<0.13 m) the advancing front (C/C0 = 0.01) of the nonreactive solute tracers, bromide and 18O, migrated at rates of 0.01 to 0.07 m/d, over distances of 4 and 6 m and under a lateral hydraulic gradient of 0.24. In this same zone, two strains of colloid-sized bacteriophage tracers migrated at rates of 2 to >5 m/d. Simulations with a discrete fracture/porous matrix flow and transport model, which used the cubic law for flow in fractures, showed that diffusion of the solutes, but not the much larger colloids, into the matrix pore water between fractures is sufficient to cause the observed difference in solute and colloid transport rates. Transport-derived and hydraulic conductivity-derived fracture aperture values …
Field Experiments In A Fractured Clay Till: 1. Hydraulic Conductivity And Fracture Aperture, Larry Mckay, John A. Cherry, Robert W. Gillham
Field Experiments In A Fractured Clay Till: 1. Hydraulic Conductivity And Fracture Aperture, Larry Mckay, John A. Cherry, Robert W. Gillham
Larry McKay
Field values of horizontal hydraulic conductivity measured in the upper 1.5–5.5 m of a weathered and fractured clay-rich till were strongly influenced by smearing around piezometer intakes, which occurs during augering, and by the physical scale of the measuring device. Values measured in conventional augered piezometers were typically 1–2 orders of magnitude lower than those measured in piezometers designed to reduce smearing. Measurements of hydraulic conductivity in small-scale seepage collectors or piezometers, which typically intersect fewer than 10 fractures, vary over a much greater range, 10−10 to 10−6 m/s, than large-scale values based on infiltration into 5.5-m-deep trenches which intersect …