The American Creosote Works (ACW) site is an abandoned wood preserving facility located in rural Louisville, MS. The ACW facility treated wood products with creosote and pentachlorophenol (PCP) from 1902 until 1981 when it filed for bankruptcy protection. Facility operations resulted in extensive soil, sediment, and groundwater contamination over the 120-acre property. Major contaminants are volatile organic compounds, polycyclic aromatic hydrocarbons, PCP, and dioxin. Creosote DNAPL has been observed to a depth of about 30 ft below ground surface (bgs) in many of the monitoring wells and subsurface soil borings. Creosote was seeping into Hughes Creek, a small stream that runs along the northern boundary of the site.

Hughes Creek became EPA Region 4 contracted Black & Veatch to perform the Remedial Investigation (RI)/Feasibility Study (FS) and the Remedial Design (RD) for the site. Black & Veatch also supported EPA with the preparation of the Proposed Plan and Record of Decision (ROD). The complex geology consisting of clay with interbraided sand lenses made it difficult to determine groundwater flow and the extent of creosote contamination. Black & Veatch developed a sampling plan that included a combination of direct push technology (DPT), hollow stem auger, and Rotosonic drilling methods to map the subsurface lithology. Several direct push temporary monitoring wells were sampled along with the site’s monitoring well network, to determine the levels of contamination within the perched water.  A permeable lignite layer was discovered that provides a subsurface conduit for creosote migration to offsite properties. This permeable layer was sealed off using jet-grouting techniques during the Remedial Action.

 so contaminated with creosote, that no aquatic life was observed in the portion of the stream adjacent to the site during the ecological field reconnaissance. Creosote contamination was found within the creek over one-half mile downstream from the site. The site geology is complex consisting primarily of clayey soils interbedded with lenses of sandy soils. The sand lenses provide conduits that allow creosote and highly contaminated ground water to migrate laterally throughout the site and continuously seep into Hughes Creek.

Ecological habitats at the site are complex and include a mix of aquatic, riparian, grass fields, shrubland areas, and upland forest communities.  Black & Veatch evaluated exposure routes, specifically via bioaccumulation through the food web and direct contact with contaminated media, to specific receptors in the identified habitats. The field team collected environmental media at the site for laboratory analysis. Ecological based cleanup goals were calculated based on the results of the ecological risk assessment (ERA). The ERA progressed through the entire 8-step process, with both EPA and MDEQ providing input at the Scientific/Management Decision Points.

EPA headquarters commented, “The risk assessment discussion was particularly comprehensive, and the analyses provided in the human and ecological risk discussions was logical and well-reasoned regarding the key issues to consider and the basis for EPA’s conclusion that remedial action is needed.”