The Precision National Plating Site is located at 198 Ackerly Road, Clarks Summit, Pennsylvania, approximately 10 miles north of Scranton, Pennsylvania. The property measures 46 acres, approximately five acres of which were used for site operations and the remainder of which are undeveloped and largely wooded. A 45,000 square foot operations building that was demolished in 2000 was the principal structure on the site. Portions of the concrete slab floor remain and are utilized as a staging area for materials during cleanup.
The site began operation as a chromium electroplating facility for locomotive crankshafts in 1956. This operation continued when Precision bought the facility in 1971. Precision operated an industrial component reconditioning facility on site from 1971 until 1999. Site operations ceased in April 1999.
In September of 2005, EPA approved a Remedial Action Plan, submitted on behalf of Precision National Plating by the Retec Group. The Plan details procedures for use of calcium polysulfide to reduce the hexavalent chromium in the soils and groundwater to trivalent chromium, a less toxic form of chromium, which will precipitate and remain in the soil/bedrock matrix.
In July 2006, Precision injected calcium polysulfide into source areas at the site. The goal of the treatment was to reduce hexavalent chromium levels in soil to below 60 mg/Kg, and hexavalent chromium levels in Ackerly Creek to below 11 ug/L.
In March 2007, Precision began excavation of the basement of the former facility. The purpose of the removal was to mitigate impacts by potentially contaminated soils beneath the basement. Any visually contaminated soil and concrete encountered during the excavation was shipped offsite to an appropriate disposal facility.
Additional site investigation activities were performed in the Fall of 2007 and February/March 2008. The soil boring, rock coring and groundwater sampling activities completed in October 2007 and March 2008 confirmed that residual source contamination remains at the Site in the shallow weathered and competent bedrock (18 - 30 feet below the ground surface).
In August 2008, Precision began using calcium polysulfide in-situ chemical injections to treat these residual areas of contamination in the shallow bedrock. Hexavalent chromium levels dropped in Ackerly Creek due to chemical injection treatments in July 2006, the basement excavation in March 2007, and subsequent injection activities.
Precision and EPA signed an Administrative Settlement Agreement and Order on Consent on May 3, 2012. On July 30, 2012, Precision's contractor, Arcadis U.S. Inc, submitted a new Response Action Plan, detailing ongoing activities. Multiple rounds of calcium polysulfide injections were conducted between Fall 2012 and Fall 2018.
Between 2016 and 2020, semi annual and quarterly sampling events occurred to document hexavalent and total chromium levels throughout the site in absence of ongoing injection activities. Injections appear to have been effective at the former site footprint and nearby areas. Some hexavalent chromium continues to persist in isolated areas and further downgradient towards Ackerly Creek. The 2020 injection activities will focus on these remaining areas of hexavalent chromium contamination.
During the week of November 23, 2020, 2,387 gallons of 2% calcium polysulfide solution were injected/gravity fed/poured into 18 wells. Injection activities were completed on Tuesday November 24, 2020.
On Wednesday November 25 and during the week of November 30, 2020, personnel packed up the site and materials following completion of activities. During this round of activities, a total of 62,178 gallons of 1%, and 5,349 gallons of 2% calcium polysulfide were injected into wells in the contaminated groundwater plume area.
24-hour air monitoring stations are operating at locations near Ackerly Creek and in the lagoon area which supplements handheld air monitors operated by site personnel during working hours. Air monitors measure hydrogen sulfide concentration, a byproduct of the injection chemical, with a lower detection limit of approximately 3 parts per billion (ppb). The hydrogen sulfide site specific action level for nuisance odors is 30 ppb. To date, no hydrogen sulfide was detected above the lower detection limit in any of the air monitoring stations.
Post injection sampling will be conducted in January 2021. Sampling of surface water in Ackerly Creek, residential wells, and all semiannual sampling groundwater monitoring wells. EPA will collect split samples of Ackerly Creek. Any locations determined to still contain calcium polysulfide solution will not be sampled.
The lagoon treatment system and seep shed treatment system will continue operation. Systems will be maintained monthly including sample collection.
Semiannual sampling will be conducted in April 2021.