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Record of Decision System (RODS)

SOUTHERN MARYLAND WOOD TREATING

Abstract

Site Name:  SOUTHERN MARYLAND WOOD TREATING
Address:  STATE ROUTE 235 
City & State:  HOLLYWOOD  MD  20636
County:  ST. MARY'S
 
EPA ID:  MDD980704852
EPA Region:  03
 
NPL Status:  Deleted from the Final NPL
 
ROD Type:  Record of Decision
ROD ID:  EPA/ROD/R03-95/197
ROD Date:  09/08/1995
Operable Unit(s):  02
 
Media:  soil, sediment, groundwater, surface water
 
Contaminant:  Benz(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, chrysene, dibenz(a,h)anthracene, indeno(1,2,3-cd)pyrene, acenaphthene, anthracene, fluoranthene, naphthalene, phenanthrene, pyrene, p-chl carbazole, pentachlorophenol, phenol, 2,3,4,6-tetrachlorophenol, 2,4,5-trichloro
 
Abstract:  Please note that the text in this document summarizes the Record of Decision for the purposes of facilitating searching and retrieving key text on the ROD. It is not the officially approved abstract drafted by the EPA Regional offices. Once EPA Headquarters receives the official abstract, this text will be replaced.

The Southern Maryland Wood Treating Site (SMWT or site), approximately 25 acres in size, is located west of Maryland Route 235 on a 96-acre parcel of land approximately one mile north of Hollywood, Maryland. The operation of a pressure treated wood preservation facility on the site for many years resulted in contamination of soils, groundwater, surface water and stream sediments with wood preserving chemicals. No wood treating activities are currently performed on site.

The site is bounded by residential, agricultural, and wooded tracts of land. An on-site freshwater pond discharges to Old Tom's Run, which eventually reaches Breton Bay and finally the Potomac River. Currently the only building structures left on-site that were once associated with the wood preservation business are a pole barn previously used for wood storage, and a small house in the upper site area formerly used as an office.

The original process building, which has since been demolished, housed the wood pressure treatment operations including two treatment vessels or retorts. Wood and chemical preservatives were introduced into the vessels which were subsequently pressurized to treat the wood. Several large vertical tanks previously located next to the process building contained the chemical preservatives pentachlorophenol (PCP) and creosote, which were used in the wood treating process.

According to the 1990 census, the population of St. Mary's County is approximately 76,000. Because the county is located along 400 miles of shoreline on the Potomac and Patuxent Rivers and the Chesapeake Bay, the population increases substantially during the summer. On a more local basis, there are several residential subdivisions and numerous houses within a two- mile radius of the site.

In 1975, SMWT took over the property. The wood treating facility was owned and operated by SMWT and subsequently operated by L.A. Clarke and Son, Inc. (L.A. Clarke), from 1965 to 1978 as a pressure treated wood preservation business. Creosote and PCP were used as wood preservatives at the site.

There are six unlined lagoons that were used for disposal of liquid waste from the process. As a result of such disposal, on-site soils and groundwater beneath the lagoons became contaminated. Non-aqueous phase liquids (NAPLs) are also found in the subsurface beneath the lagoons and above the underlying clay layer. Additionally, due to groundwater discharge to the pond from the lagoon area, surface water and sediment in the on-site pond and sediment in the west tributary became contaminated. Sediments in the east tributary are also contaminated, most likely due to surface water runoff from contaminated soils onsite. Storage of treated wood on site resulted in surface soil contamination in the upper site and northeast tank areas.

The contaminants of concern for this site are polyaromatic hydrocarbons (PAHs), PCP, and other organic compounds.
 
Remedy:  This is the second and final phase of remedial action for the site. This phase addresses soil and sediment contamination and NAPLs which are the principal threats remaining at the site and are a source of contamination to the groundwater and surface water. Because the soil and sediments will be treated to levels that are protective of human health and the environment before backfilling on site, and the NAPLs will be disposed of offsite, the site will not require long-term management.

The major components of the selected remedy include the following: dewatering of the containment area in preparation for the excavation of subsurface soil and dense non-aqueous phase liquids (DNAPLs) below the water table followed by on-site treatment of water generated in the dewatering process and discharge of treated water to the west tributary; excavation of approximately 97,000 cubic yards (CY) of soil from within and outside of the sheet pile wall and dredging of sediments from the on-site pond and segments of the east and west tributaries that contain contaminants in excess of the established cleanup levels; dewatering of saturated soils/sediments onsite in preparation for treatment of water generated in the dewatering process and discharge of treated water to the west tributary; and staging of excavated soil/sediments onsite in preparation for dewatering, following dewatering in preparation for treatment by thermal desorption, and following thermal desorption in preparation for backfilling. Also, on-site staging of NAPLs collected during excavation and dewatering, water treatment residues, recondensed contaminants from the thermal desorption treatment process, and any grossly contaminated soil/sediment that is not amenable to treatment by thermal desorption prior to offsite shipment for treatment and disposal; on-site treatment of excavated soils and sediments by a thermal desorption process; off-site treatment and disposal of desorbed, recondensed contaminants from the thermal desorption treatment process, NAPLs collected during excavation and dewatering, water treatment residues, and any grossly contaminated soil/sediment that is not amenable to treatment by thermal desorption; sampling of treated soils and sediments to ensure delisting levels have been achieved; backfilling with clean fill below the water table in the containment area and with treated soil/sediments above the water table in the containment area and in all other excavated areas; pumping and treating of surface water from the onsite pond until the sources of contamination to the surface water are remediated, treatment of surface water in on-site water treatment system followed by discharge to the west tributary; groundwater stream and wetlands monitoring; implementation of institutional controls temporarily restricting groundwater used in the shallow aquifer; building demolition and cutting off of the sheet pile wall following remediation as determined necessary; off-site disposal of building rubble and sheet piling; and maintenance of perimeter fencing until access restrictions are no longer necessary.
 
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