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.
Injections began on August 17, 2020 and will continue through the Fall 2020. During the week of October 5 to 9, 2020, a total of 3,457 gallons of 1% calcium polysulfide (CaSx) was gravity fed into fourteen wells.
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.
During the afternoon of October 7 & on October 8, 2020, approximately 490 gallons of 1% CaSx was injected into one of the 2020 installed wells as part of the regular injection activity. New wells were installed in September 2020 in order to better characterize the extent of the hexavalent chromium contamination. The new well was installed to the east of the 2018 wells at about the same distance from Ackerly Creek.
On Friday morning, October 9, Precision contractors informed EPA that dilute calcium polysulfide was surfacing in Ackerly Creek. The gravity fed injection activities immediately ceased and PA DEP was contacted. The well was pumped out and approximately 25 to 30 gallons of injection chemical was recovered from the well. Following the incident and during the day, pH in the creek was tested and found to be unchanged.
Additionally, water quality parameters were monitored on Friday and throughout the weekend by Precision contractors and PA DEP and were found to be stable. Any possible impacts to the creek were mitigated by the dilution of the injection chemical by groundwater and creek water flow. Injection chemical will no longer be introduced to this particular well in the future.
Discharge related sampling was completed by Precision contractor in the creek and at other locations on Friday October 9 and on Monday October 12, 2020.
Injection activities will continue Monday to Friday into November 2020. These activities and associated sampling as described in the In-Situ Chemical Reduction Work Plan will continue.
As previously scheduled, downhole geophysical logging to evaluate the bedrock characteristics in newly installed wells will be completed during the week of October 19, 2020.
Semi-annual well sampling will be conducted during the week of October 12, 2020.