Southern Pine Wood Preserving is a 5.5 acre site located at 1418 College Avenue, Wiggins, Mississippi. It is located in a residential area and the property is zoned residential. The nearest residence is located within 200 feet of the site. Surface water from the site flows primarily to the south and southwest to Fourmile Creek.
Operations at Southern Pine included impregnating wood products with creosote and pentachlorophenol (PCP). Operations began in 1960 and ceased in 1984. A dilapidated wooded structure is all that remains on site from the wood preserving operation.
The Mississippi Department of Environmental Quality (MSDEQ) referred the site to EPA in November of 2008. EPA subsequently conducted a Removal Site Evaluation (RSE) to determine if a removal action was warranted. The assessment scope included surface and subsurface sampling, local interviews, and the identification of various environmental and physical hazards at the site.
The RSE revealed significant amounts of source material containing PCP and Polychlorinated Aromatic Hydrocarbons (PAHs) at or near the surface on a large portion of the site. Dioxins were also discovered in limited quantities and limited areas of the site. All contaminants were present at concentrations above EPA Region 4 Removal Action Levels (RALs). Based on these concentrations and other conditions at the site documented in the Action Memo, site conditions meet the requirements for initiating a time-critical removal action according to criteria listed in Section 300.415 (b)(2) of the National Contingency Plan (NCP).
During the week of September 28, 2009 START mobilized to the site to conduct the removal site sampling (second soil sampling event) to assess areas of concern not covered by the removal site assessment conducted in March 2009 (first soil sampling event). Areas included in the sampling consisted of the suspected process area, laydown yard, low lying areas near and along Fourmile creek, and adjacent properties to the south and east of the site. ERRS continued site clearing activities as well as trash and debris removal.
During the week of October 5, 2009, ERRS completed clearing activities sufficient to begin removal of site surface soils exceeding the site-specific removal action levels (RALs) for contaminants of concern (COCs). The site entrance was secured with safety fencing and a traffic flow plan was developed to improve traffic flow, limit potential cross contamination, and prepare for the load out of contaminated soils. Silt fencing was placed downgradient of disturbed areas to mitigate any off site migration of contaminated soils during rain events. A soil stockpile area was identified and prepared to receive excavated soil. A partially buried concrete pad located within the removal area was identified and removed for disposal.
Preliminary data from the September 2009 sampling event was received late in the week. A proposed removal area was defined based on all soil data received to date that indicated levels of surficial contamination above the site-specific RALs. START marked the proposed removal area boundary in the field with a Trimble GPS unit and staked the corners with wooden stakes.
The excavation will consist of a two foot initial excavation of the proposed removal area as well as spot excavations of visible contamination observed beyond the identified removal boundary or below two feet. Once the initial excavation is complete in each cell, START will take composite soil samples to assess whether site cleanup criteria have been achieved and contamination above the site-specific RALs has been removed. Once data is received which confirms site cleanup criteria have been met for an excavation cell, ERRS will begin backfilling the cell with clean backfill. Higher levels of contamination are expected on the western side of the site and contamination may extend deeper than two feet. The OSC will make a determination of excavation depth below two feet on the western side of the site based on visible staining and other indications of potential future migration of contaminants offsite towards Fourmile Creek.
During the week of October 12, 2009 ERRS began the two foot excavation in the northeast corner of the site. ERRS is excavating contaminated soil based on a grid laid out by the OSC, ERRS RM and START field lead. The excavation is planned to proceed in a westerly direction beginning from the highest site elevation in areas with lower levels of contamination and working towards the lower site elevations in areas with higher levels of contamination. Initial visual inspection of the first excavation cell shows contamination is limited to the top two feet of soil with only a few isolated areas showing visible contamination below two feet. These areas are being included in the excavation to ensure site cleanup criteria are met.
ERRS will continue excavation of contaminated soil down to two feet within the removal area. After cell excavation is complete, START will sample and confirm concentrations are below RALs. ERRS will then begin backfilling the cells.
The second round of sampling confirms that contamination extends south of the property line. However, it appears that contamination is limited to roughly 40 to 60 feet south of the property line in isolated areas. Based on the observable amount of process related debris located along the southern property line and historical aerial photographs, it is suspected that closure activities on site (ie. pushing debris and materials to the rear of the site) along with site drainage may have contributed to contamination slightly beyond the southern property boundary. The OSC will attempt to gain removal access from the corresponding landowner in order to include this area in the ongoing removal action.
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