USING ORGANIC PETROLOGY TECHNIQUES TO ASSESS COAL AND COMBUSTION BY-PRODUCT CONTAMINATION IN SEDIMENTS OF THE KINNICKINNIC RIVER IN MILWAUKEE, WI

As part of an ongoing CERCLA re-assessment of the Milwaukee Solvay Coke and Gas Company site, the Wisconsin Dept. of Natural Resources asked the USGS Organic Petrology Laboratory to develop methods to quantify the amount of coal and combustion by-products (i.e., coke, coal tar/pitch, cenospheres) in sediments of the Kinnickinnic River which borders the site. The Solvay plant produced metallurgical coke and coal-gasification by-products from 1904-1983, and was assessed in 2001 as a potential Superfund site in part due to high levels of polycyclic aromatic hydrocarbons (PAHs) which readily absorb to coal and combustion by-products.

River bottom samples (n=35) ranging in depth from 1-12 ft. were collected from eight core locations upstream, downstream and adjacent to the Solvay site to determine the movement of coal and combustion by-products in the river. Preparation of the samples was completed without crushing to preserve existing particle size, dry-sieved (18 mesh), split and mounted in two petrographic pellets per sample. To determine the amount (vol. %) of organic particulates, USGS modified the existing ASTM D2799, Standard test method for microscopical determination of maceral composition of coal to quantify coal, coke, coal tar/pitch, inert organics, plant material, cenospheres and mineral matter. Coal fragments were subdivided by rank using vitrinite reflectance (R_o %) and organic components were further subdivided into size fractions of coarse (250-1,000 µm), fine (63-250 µm), and very fine (<63 µm) as other studies have indicated that PAH concentrations are greatest in the very fine size fraction for Milwaukee Harbor sediments.

Of the 35 samples analyzed, concentrations of coal, coke, and coal tar/pitch ranged from 0-18.2 vol. % (mean 5.1 vol. %), 0-32.0 vol. % (mean 10.4 vol. %), and 0-2.6 vol. % (mean 1.2 vol. %), respectively, with highest concentrations occurring near known discharge pipe and barge operation locations. Samples that were furthest upstream and downstream showed a marked decrease in particulate organics, with exception of one upstream location which had 19.8 vol. % coke. The samples with the highest vol. % of fine to very-fine organic particles from each core generally corresponded to the highest PAH concentrations in five of the eight cores used in the study.