The Army will hold a public information meeting in Edgewood next week to go over its findings in connection with a former salvage site on Aberdeen Proving Ground, where a small amount of radioactive material was found beginning in 2009.
The material – 17 small radioluminescent devices most likely used by the Navy to illuminate the outline of ships' decks or repair docks at night – was found in an area known as G Street Salvage Yard on the Edgewood Area of APG, according to a fact sheet the Army released last week.
In the fact sheet, the Army said it has concluded that the radioactive material in the devices has not adversely affected the environment and no remedial action is required at the site or in surrounding soil or groundwater.
The public information meeting on the Army's findings and "No Action" proposal will be held on Thursday, Feb. 28, at the Ramada Conference Center, 1700 Van Bibber Road in Edgewood. The meeting will include a one-on-one poster/information session beginning at 6 p.m., followed by a presentation at 6:30 p.m.
A 30-day public comment plan period on the Army's proposal began Feb. 16 and will run through March 18.
The Edgewood Area of APG has been classified a federal Superfund Site by the U.S. Environmental Protection Agency and is on the final National Priorities List, or NPL, which the EPA says "is the list of national priorities among the known releases or threatened releases of hazardous substances, pollutants or contaminants throughout the United States and its territories."
According to the Army fact sheet, the one-acre "G-Street Radiation Site," as the Army now refers to it, is in the Canal Creek Study Area, where the Army has been involved a number of federal Super Fund-related cleanup activities for several years.
The site is within 800 feet of the Edgewood Area main gate off Hoadley Road [Edgewood Road – Route 755 extended] and about 2,000 from the post's northern boundary with the Edgewood community. The radiation site is west of Hoadley Road and is adjacent to a site the Army refers to as the G-Street Burn Residue Area.
The radiation site was identified during a radiological background survey in connection with the cleanup of the salvage yard and burn residue and disposal area. According to the Army fact sheet, the salvage yard area was active from the 1940s to the late 1960s and was a railroad siding area during World War I and the years prior to World War II.
From historical research, the Army says it did not believe any industrial or disposal activities took place on the radiation site; however, elevated radiological readings were observed during the background survey and a subsequent walkover of the site found 13 radioluminescent deck markers, which the Army removed. During a remedial investigation feasibility study that followed two years later, four more deck markers were discovered and removed.
According to information posted on the website of the Oak Ridge Associated Universities, beginning in the 1930s (other sources say in the World War I era), the United States armed forces developed and used various radioluminescent disks or markers to provide low level light sources for use at night, including a personnel marker that could be clipped to belts or helmets to enable soldiers or sailors to identify each others positions.
Deck markers, primarily used by the Navy, were about 1.5 inches wide and did not have a clip but were attached to the deck of the ship with two screws and had a luminous area about one-inch wide protected by a thick plastic cover. The Army also used a bridge marker used to illuminate outlines of bridges and vehicles, according to the ORAU website.
Light was generated by a compound containing the radioactive isotope Ra-226 in amounts measured in 5 to 15 microcuries, a measure of radioactive decay. Increasing the Ra-226 activity increased the light output, according to the ORAU website. The radium was typically mixed with a zinc sulfide crystals to produce the illumination.
Beginning sometime in the 1950s, manufacturers began using the isotope Sr-90 instead of radium and by the late 1960s, Sr-90 had replaced Ra-226 completely. According to the ORAU website, the strontium isotope was believed to have three advantages: greater variety of colors could be achieved, less decrease in luminous intensity because strontium beta particles did less damage to the zinc sulfide crystals than radium's alpha particles and photon emissions from strontium were less of a safety concern than gamma rays from radium.
The ORAU website notes, however, that "because a beta particle will not produce as much light as an alpha particle, Sr-90 activities were substantially higher than the activities in radium containing markers: 0.2 to 1 mCi [millicuries] per marker!" As a measurement of decay, one millicuri equals 100 microcuries, according to the U.S. Centers for Disease Control's radiation emergencies fact sheet.
The ORAU website also notes that radioluminescent markers were stored in lead lined boxes marked "poison," a transportation classification dating from the 1940s. On some markers, "poison" was stamped into the metal backing.
The radioactive material used in the deck markers found at the G-Street Radiation Site was RA-226, Bonnie Smith, a spokesperson for EPA's Region III Office in Philadelphia, said Tuesday.
Soil, groundwater samples
The fact sheet says the Army collected soil and a groundwater sample from the site and both were evaluated for human health and ecological risk assessments and, based upon conclusions from those assessments, "no unacceptable risks were identified for human health or ecological receptors." The fact sheet adds that "groundwater beneath the C-Street Radiation Site is part of an ongoing RI [remedial investigation] for the West Branch Canal Creek Aquifer for other non-radiological contaminants."
"It is the Army judgment that no action is required at the G-Street Radiation Site to protect the public health or welfare and the environment," the Army fact sheet concludes, noting that previous remedial investigations and feasibility studies "were used to determine that the site has not been impacted by radiological-related contaminants."
The fact sheet also notes that "because no unacceptable contamination levels remain at the G-Street Radiation Site, no other cleanup alternatives were evaluated."
Smith said that when the first 13 devices were found, the specific location was not immediately recorded, nor did the Army immediately conduct an assessment of potential contamination at that time. Later, when the Army did an actual remedial investigation assessment of the area in two phases during 2011, the additional four markers were found, Smith said.
The Army conducted gamma surveys to determine background radiation before looking for elevated levels of Ra-226 in air, soil and groundwater samples around the site, noting that "there did not appear to be discernible hot spots of contamination or evidence associated with a release, especially considering that onsite concentrations are comparable to background."
A human health risk assessment was also performed on the site and did not identify any potential human health concerns. The consultants working on the assessments were EA Engineering, Science and Technology and Cabrera Environmental.
According to the final version of "Proposed Plan – Edgewood Area – G-Street Radiation Area," the area immediately to the south of the site "is designated for Enhanced Use Lease for activities such as research, development, testing, evaluation and other activities, specifically targeting Base Realignment and Closure [BRAC] tenants. Amtrak railroad tracks are to the north."
"The site does not present any unacceptable risks to human health or the environment; therefore, the preferred remedy for the G-Street Radiation Site is No Action, which includes no further environmental investigation or remediation," the proposed plan concludes. "Under the No Action alternative, no monitoring, evaluations or remedial measures would be required on the G-Street Radiation Site."
Both the Harford County Public Library's Aberdeen and Edgewood branches contain depositories for technical reports and other information on the APG environmental program, including the documents regarding the G-Street Radiation Site.