In July 1985, members of the Radiological Survey Activities (RASA) Group at Oak Ridge National Laboratory (ORNL) performed a radiological survey of the Site for the U.S. Department of Energy (DOE), which documented a maximum gamma exposure rate of 710 microroentgens per hour (μR/hr). The area with these readings was approximately 10 feet wide by 59 feet in length and located along a ditch and gravel residential driveway. The results of the survey were documented in a November 1986 report, which stated that the gamma radiation anomaly at the Site was associated with a phosphate slag material. Biased surface soil samples collected during the survey indicated the presence of Radium-226 (Ra-226), Uranium-238 (U-238), and Thorium-232 (Th-232) at the Site. The contaminated soil and rock samples collected had approximately equal concentrations of Ra-226 and U-238, which suggested to the investigators that the rocks probably originated from a singular source. The origin of the material was unknown; the report postulated that its source was some type of mineral extraction activity in the Niagara Falls area. The report stated that the anomaly at the Site was not related to materials connected with the Niagara Falls Storage Site (NFSS), including materials that were transported to NFSS.
During a reconnaissance performed by the New York State Department of Health (NYSDOH) and the New York State Department of Conservation (NYSDEC) on July 9, 2013, screening activities showed radiation levels at 300 µR/hr with a hand-held pressurized ion chamber. The background readings for this Site were approximately 10 µR/hr. Surveying with the sodium iodide 2x2 scintillation detector, the highest readings ranged from 105,000-110,000 counts per minute (CPM), with the estimated background readings at the Site being 9,000 CPM. Both elevated measurements were obtained at the end of the driveway adjacent to Upper Mountain Road. The NYSDEC and NYSDOH referred the Site to EPA on July 21, 2013 for further assessment.
In September 2013, the EPA Region 2 Pre-Remedial Section (PRS) initiated a preliminary assessment (PA) and site inspection (SI) to assess whether the Site posed a threat to human health and the environment. An on-site reconnaissance was conducted on September 10, 2013 to perform a gamma radiation screening. Elevated gamma readings were observed toward the end of the driveway close to the road in an approximately 45-foot by 45-foot gravel area. The readings in the area of elevated gamma radiation ranged from background levels (approximately 9,000 CPM) to greater than 300,000 CPM.
On December 12, 2013, PRS and EPA contractor (Weston Solutions, Inc.) personnel collected a total of nine soil samples (including one environmental duplicate sample) and two slag samples from the Site. Soil samples were also collected from two locations suspected to be outside the influence of the observed contamination to document background conditions. At each location, soil samples were either collected directly beneath slag material or, at locations where a radioactive layer was not present, at the equivalent depth interval. The slag samples consisted of pulverized silty sand with rocks, cobbles, and gravel (i.e., radioactive waste material mixture) rather than singular pieces of slag.
The soil, slag, and aqueous rinsate blank samples were analyzed by Test America Laboratories for Target Analyte List metals analyses, including Mercury; Isotopic Thorium, Isotopic Uranium, and Ra-226 by alpha spectrometry; and other radionuclides by gamma spectrometry. Analytical results indicate concentrations of radionuclides found in the slag and soil to be higher than at background conditions.
On May 1 and 2, 2014, PRS and Weston Solutions, Inc. personnel collected radon and thoron concentration measurements from locations on and in the vicinity of the Site. These measurements were collected with RAD7 radon detectors at the selected locations in background areas, above the source material, and off the source area. The radon and thoron measurements were collected at heights of one meter above the ground surface. There were no radon or thoron concentrations that exceeded the site-specific background.
Based on the PA and SI results, a Hazardous Ranking System (HRS) score was calculated. The calculated HRS score for the Site was less than 28.5 and, as a result, the Site did not qualify for inclusion on the NPL. The Site was referred to the Emergency and Remedial Response Division (now known as the Superfund and Emergency Management Division or SEMD) Removal Action Branch (RAB) for a determination as to whether the Site warranted a CERCLA removal action.
The RAB and an EPA Region 2 risk assessor utilized the PRS data site files, which included a Pre-CERCLIS Screening Form for the Site, as well as historic city directories, Sanborn maps, and analytical data collected for the Site, to conduct a preliminary RSE. In addition, an internet search for historic articles, maps, and photographs was conducted, and historic aerial photographs and online Erie County property records were reviewed. In June 2015, it was determined that conditions at the Site did not meet the requirements of Section 300.425(b) of the National Contingency Plan for the undertaking of a CERCLA removal action.
On September 23, 2016, RPB OSC was assigned as the lead for the Site to conduct a reassessment of the removal eligibility with the collection of additional field data. The reassessment utilized EPA’s Preliminary Remediation Goals (PRG) Calculator. PRG calculations were performed by EPA Environmental Response Team (ERT) Health Physicist to determine whether the Site warranted a CERCLA removal action.
On October 25, 2016, EPA Response and Prevention Branch (RPB) and Weston Solutions, Inc. personnel performed a gamma survey at the Site. The highest gamma reading recorded was approximately 462 µR/hr in comparison to a background reading of approximately 10 µR/hr.
On November 18, 2016, RPB and Weston Solutions, Inc. conducted soil sampling at 738 UMR Site at several locations on the Site.
On December 06, 2016, the soil samples collected were analyzed on-site with a High-Purity Germanium (HPGe) Detector. Once completed, the samples were shipped to a third-party fixed analytical laboratory for analysis for isotopic Uranium and isotopic Thorium by alpha spectrometry, 21 day in-growth for Ra-226, U-238 decay chain radionuclides, and Th-232 decay chain radionuclides by gamma spectrometry. On February 23, 2017, the preliminary soil sample results from the fixed analytical laboratory were received.
On August 11, 2017, RPB and Weston Solutions, Inc. conducted an indoor gamma survey of the home located on the Site. There were no elevated gamma readings identified above background levels. A radon specialist placed radon canisters throughout the home.
On August 18, 2017, the radon laboratory results were received indicating that radon levels in the building tested were below the EPA action level of 4.0 pCi/L. Mitigation was not recommended under the existing conditions.
The focus of the RSE was placed on utilizing analytical data from soil samples collected as part of the assessment in November 2016, the gamma survey and radon sampling results, and the PRS assessment data.