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Hazardous Waste Cleanup: Chevron Molycorp Washington Remediation Project in Washington, Pennsylvania

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The Molycorp, Inc. facility, currently owned by Chevron Mining Inc. (Chevron), is enrolled in the "One Cleanup Program" between EPA and the Pennsylvania Department of Protection (PADEP) to address the Resource Conservation and Recovery Act (RCRA)-related concerns at the site.  The facility has also been decommissioned under the authority of PADEP’s Bureau of Radiation Protection (BRP) as of December 2010.   

Cleanup Status

Molycorp submitted a Notice of Intent to Remediate (NIR) to PADEP in January 2005, in which it sought a release of liability under the Pennsylvania Land Recycling and Environmental Remediation Standards Act (Act 2) using a combination of Statewide Health Standards and Site-Specific Standards for soil and groundwater.  All operations at the facility have ceased and all existing operational structures on the property, including storage tanks, have been removed from the site.  Remedial activities, including the removal of 104,000 cubic yards of radiological materials and 71,000 cubic yard of manufactured gas plant (MGP) tar and soil containing tar, were completed in June 2009.  Chevron also developed a former MGP tar pond into a 3.6-acre functioning wetland habitat and repaired and realigned a state-owned storm sewer system which greatly reduced the amount of contaminated runoff and groundwater discharging into Chartiers Creek.  An Act 2 Final Report was submitted to PADEP in April 2011 and PADEP approved of the report on August 3, 2011.    

Engineering controls in place at the facility include the barrier of a minimum of two feet of clean soil in areas where excavation occurred during remediation.  A concrete shipment pad built for the remediation effort will stay in place as a permanent barrier to remaining contamination in the former North Process Area of the facility.  Additionally, a sheet pile/jet grout wall was installed along the eastern boundary of the facility in the vicinity of Interstate I-70 to prevent seepage of coal tar from beneath the roadway onto the facility. 

An Environmental Covenant for the facility was executed on September 27, 2011 that includes institutional controls requiring a site-wide ban on groundwater usage, area-specific non-residential designations, and engineered cap maintenance requirements and excavation precautions.

The Molycorp facility achieved a “Yes” determination for the Current Human Exposures Under Control Environmental Indicator (EI) in October 2003 and a “Yes” determination for the Migration of Contaminated Groundwater Under Control EI in December 2011.

EPA issued its public notice for the Statement of Basis for the facility on August 7, 2012.  EPA's proposed decision does not require anything in addition to what has been required/approved by PADEP and relies on the existing Environmental Covenant. A public meeting to discuss the proposed remedy was held at the Canton Township Municipal Building on December 10, 2012.  The extended public comments period ended on December 17, 2012. Based on the received comments, EPA has determined that no changes to the proposed remedy are necessary. On December 28, 2012, EPA issued its Final Decision and Response to Comments which designated the proposed remedy in the Statement of Basis as the final selected remedy.  

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Site Description

Interactive Map of Chevron Molycorp Washington Remediation Project, Washington, Pennsylvania


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Molycorp operated a ferrous and nonferrous alloys plant in Washington, Pennsylvania from the 1920s through 2001, when operations ceased.  Molybdenite ore was first processed at the plant in 1930.  From 1964 to 1970, Molycorp produced a ferrocolumbium alloy from a Brazilian ore (pyrochlore) that contained radioactive thorium as an accessory metal.  During processing of the pyrochlore, a thorium-bearing slag was generated, some of which was used as fill material over portions of the site.  Much of the material was subsequently excavated and placed into a pile on property south of Caldwell Avenue across the street from the former plant area.  About 4,000 cubic yards of thorium-contaminated slag and soil were removed from along the northern property boundary on land owned by Findlay Refractories Company and placed into roll-off containers.  The pile and roll-off containers were removed from the site and properly disposed of off-site with Nuclear Regulatory Commission (NRC) approval in 2001.  The remaining radiologic contamination was addressed by the BRP prior to the facility’s license termination in December 2010 as described in the Status section above.

In the late 1960s, Molycorp built eight surface impoundments used to recover molybdenum disulfide solids generated by the plant’s wet scrubber.  When a baghouse replace the wet scrubber in the mid 1970s, the impoundments were used to hold weak acids and runoff from various plant areas.  After the facility was placed on standby at the end of 1991, all liquids were removed from the impoundments.  The impoundments were certified closed by the Pennsylvania Department of Environmental Protection (PADEP) as of November 1996.

Molycorp purchased the property located south of Caldwell Avenue in August 1975 for additional storage space for the slag they were generating.  Shortly after purchasing the property, two coal tar ponds and coal tar within the foundation area of a building located on a hill in the southwest portion of the facility were discovered.  The origin of the coal tar was traced back to a manufactured gas plant owned by the Hazel Atlas Glass Company which had its operations on property to the east of the facility on the opposite side of Interstate I-70.  The contents of the north pond and coal tar collected from various seep areas were placed into the south pond in 1985.  In 1986, the walls of the building foundation were cut in half and collapsed into the foundation.  The resulting mixture of concrete and tar was covered with four feet of clean soil.  Shortly after the above work was completed, coal tar seeps were observed at the north and south ponds, the former building  foundation, and various other locations on the property south of Caldwell Avenue.  All visible signs of coal tar were removed from the site as part of the most recent cleanup activities as described in the Status section above.

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Contaminants at this Facility

Several metals including molybdenum, boron, iron and manganese remain in groundwater at concentrations exceeding EPA's regional screening levels (RSLs) for tap water. The observed groundwater contamination does not significantly impact any off-site properties or Chartiers Creek and the use of groundwater beneath the site for potable, agricultural and commercial purposes is prohibited per the Environmental Covenant.

Soils in many areas of the Facility were found to contain several contaminants above PADEP Statewide Health Standards (SHSs). Prior to remediation, Facility soils also contained licensed radiologic material at levels in excess of unrestricted release criteria. After all radiologic materials in excess of the unrestricted release criteria were removed, all excavated portions of Areas 1, 2, 3 and 10A were covered with at least two feet of clean soil which serves as an engineering control preventing exposure to any remaining residual contamination.

The remedial action included the removal of all soil with visual indications of MGP tar. Post-remedial soil samples in several of these areas attained the residential SHS for all constituents analyzed for except benzo(a)pyrene. However, the nonresidential SHS for benzo(a)pyrene was met in these areas. The North Tar Pond Area also contains concentrations of arsenic and molybdenum in the unexcavated portions that were above residential but below nonresidential SHSs. A combination of engineering and institutional controls contained in the Environmental Covenant ensures that the exposure pathways for these areas will remain incomplete.

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Institutional and Engineering Controls at this Facility

    An Environmental Covenant for the facility was executed on September 27, 2011 that requires a site-wide ban on groundwater usage, area-specific non-residential designations, and engineered cap maintenance requirements and excavation precautions.

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    Land Reuse Information at this Facility

    The site is unused.

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    Site Responsibility at this Facility

    RCRA Corrective Action activities at this facility have been conducted under the direction of EPA Region 3 with assistance from PA DEP.

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