Mineralogical Study of Borehole MW-206 Asarco Smelter Site, Tacoma, Washington

摘要

The mobility of metals in ground water is an important consideration for211u001eevaluating remedial options at the Asarco smelter site. Tacoma, Washington. One 211u001efactor in assessing metal mobility is the degree of secondary mineralization in a 211u001eslag-fill aquifer extending into the intertidal zone along the Puget Sound 211u001eshoreline. Samples of aquifer material were collected for mineralogical analysis 211u001efrom borehole MW-206 at five-foot intervals within the slag fill from 5 to 25 211u001efeet below the ground surface, and in the underlying marine sand and gravel at 27 211u001efeet. Grab samples of slag fragments with visually apparent secondary minerals 211u001ewere also collected at five intermediate depths between 12 and 19 feet. Samples 211u001ewere analyzed by a variety of of techniques including hydride generation/atomic 211u001eabsorption for arsenic concentration, scanning electron microscopy/electron 211u001emicroprobe for mineralogical texture and microanalysis, powder x-ray diffraction 211u001efor mineral identification, and optical microscopy for textural observations.