Unearthing of creek sediments combined with heavy rains at a construction site near the American Creosote Superfund Site (Louisville, MS) resulted in a release of creosote from long standing contaminated creek sediments.
The American Creosote site is an NPL site currently in the RI/FS stage. Hughes creek runs through the site, parallel to Railroad Avenue. The contamination of Hughes Creek with creosote from the American Creosote site is well documented. Offsite, at the corner of S. Church Avenue and Railroad Avenue (near the City of Louisville Water Work) the City is constructing a bridge that crosses Hughes Creek. During that construction, the creek was diverted and an exacavation pit was dug for the construction of the bridge base. The construction crew piled sediments from the creek bed along side the culvert that diverted the stream.
Construction workers noticed creosote stained soils, complained of creosote odors, and observed a sheen in the rain water that had accumulated in the excavation pit. The construction may have unearthed contaminated sediments. Another possibility is that the diverted stream, carrying creosote, breached the silt fence and berm that separated the excavation pit from the diverted stream. After the rain event, creosote globules in the sediments (and a corresponding sheen on the water) were observed upstream in Hughes creek (from either runoff or the resuspension of contaminated stream sediments). The creek could have deposited creosote when it overflowed the silt fench/berm contruction.
EPA Region 4 Emergency Response responded at the request of Mississippi Department of Environmental Quality (MDEQ). On August, 13, OSC Dorian mobilized with Ferguson Harbor (ERRS Contractor) to mitigate the impacts of the release under his delegated warrant authority. The response activities included placing sorbent boom in Hughes Creek and washing contaminated soils at the contruction site.
EPA has worked at two locations: 1. at the bridge construction site on the corner of Railroad and S. Church; and, 2. On the Hughes creek where it intersects Baremore Avenue. EPA efforts are to stabilize the situation to facilitate the resumption of the bridge construction.
A long term solution that deals with the contaminated sediments in Hughes Creek is beyond the scope of this Emergency Response phase. However, ERRB is dealing with the exposed contaminated soil and the sheen at the construction site and sorbing exposed creosote on Hughes Creek to the extent possible.
On August 14, EPA contractor attempted to remove creosote globules from the stream. OSC Dorian noted that the stream sediments contain creosote and continued migration of creosote at the groundwater-surface water interface. Although some aesthetic improvements were made, work was limited because as workers stepped in the creek bed, the pressure caused additional creosote to emerge from the sediments. For this reason, OSC decided that booms to limit further migration (i.e., stabilization) was the appropriate measure.
EPA will continue to use sorbent boom and sorbent pads on Hughes Creek at Baremore Avenue. EPA will temporarily maintain enough boom to prevent creosote from floating downstream. Ferguson Harbor will maintain the boom for a defined, short interval of time.
EPA will brief the Winston County Emergency Management Director and the City Engineers charged with constructing the bridge on the situation. EPA will make recommendations on how to minimize future creosote releases while the bridge construction is complete.
There are limits to what can be accomplished at this site. The Hughes creek sediments are saturated with creosote. Either rain or pressure (e.g., crew stepping in the creek to remove creosote globules) results in more creosote emerging from the creek sediments. Additionally it appears that there is continued contaminant migration from the subsurface to the creek (and sediments) from the American Creosote site.
Since American Creosote is already an NPL site, this is primarily an issue of offsite migration from an NPL site and needs to be dealt with as such.
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