Environmental remediation and ongoing effort at Tinker Published April 13, 2012 By Mike W. Ray Tinker Public Affairs TINKER AIR FORCE BASE, Okla. -- The Environmental Restoration Branch at Tinker is in the business of remediating "things we did 20, 30, 50 years ago," said Albert Aguilar, the branch chief. "It's not that we did anything illegal. It's just that we as a nation weren't as environmentally aware back then." For example, Tinker has six former waste-disposal landfills. The oldest was established during World War II, and the last of those landfills closed more than three decades ago, in 1979, records show. Landfill 1 contains nothing more than household trash and construction debris, records reflect. Landfills 2, 3 and 4, though, contain metal shavings, medical waste and industrial sludges, as well as household garbage, Mr. Aguilar said. All six landfills are now capped with an impermeable clay or textile barrier that prevents human and animal contact with the materials discarded in those landfills. The caps also prevent rainwater from seeping into the site, percolating through the soil and into the subterranean groundwater, said Scott Bowen, hydrogeologist with the Environmental Restoration Branch. Although none of the "trash dumps" was constructed with a liner to prevent toxic substances from leaching into the groundwater, continuous periodic testing suggests the contents of the six landfills are now largely inert. Tinker once had an unlined "evaporation pond" into which hazardous wastes were poured and left uncovered to evaporate in the sun; the site has since been covered over, Mr. Bowen said. Tinker also had two industrial waste pits, records reflect. One of those sites is no longer monitored because investigations revealed no contaminated seepage from the site, Mr. Bowen said. A liner was installed on the bottom of that former waste pit and it was covered with an impenetrable cap, Mr. Bowen said; that location continues to be monitored. Also, Tinker previously had five military munitions sites, including two skeet ranges that were littered with lead shot. However, all five of those sites have since been shut down, and much of the contaminated soil has been cleaned of the shot or altogether replaced, Mr. Bowen said. As a consequence of various practices from days gone by, "We have several groundwater contamination plumes around the base," Mr. Aguilar said. The principal groundwater contaminant is trichloroethene (TCE), a solvent that's used to clean airplane parts, he said. Years ago, TCE was used to clean parts in pits that were lined with concrete, which is porous. One contaminated groundwater plume is underneath Tinker's industrial wastewater treatment plant in the northeastern quadrant of the base. Similarly, groundwater under Bldg. 3001 is contaminated with TCE and hexavalent chromium. Bldg. 3001 is a designated Superfund site "where we work with the Environmental Protection Agency and the Oklahoma Department of Environmental Quality" to remediate degradation of the environment, Mr. Aguilar said. "Pump and treat" remediation efforts are under way on several of the contaminated groundwater plumes, Mr. Bowen and Mr. Aguilar both said. None of the 22 on-base wells from which drinking water is pumped siphons water from the polluted plumes, Mr. Aguilar emphasized. The Civil Engineering Directorate operates more than 1,200 groundwater monitoring wells, ranging from shallow depths to 225 feet, Mr. Aguilar said. Tinker personnel check those wells on a regular basis, he said, and have been collecting groundwater data for about a quarter-century, since the 1980s. "We know what's going on underneath this base," he asserted. In the 1980s and 1990s Tinker personnel singled out 40 sites that needed environmental remediation, Mr. Aguilar recalled. Two dozen of those sites have since been cleaned up or no longer require human attention because of restoration measures Tinker personnel implemented or because nature corrected the problem. For example, previously the Air Force used low-level radioactive glow-in-the-dark paint on its aircraft. When that paint was stripped off, it was concentrated into lead ingots that were buried on base. Eventually those ingots were dug up from five locations on base and were sent to an out-of-state location for disposal, Mr. Aguilar said. Of the 16 other sites, remediation activities are under way at seven of them and the other nine are being monitored for natural environmental restoration, Mr. Bowen said. Six of those 16 sites are the landfills, Mr. Aguilar said. In addition, "We have 13 relatively new compliance restoration sites," he said. Of those, nine are in a remedial investigation phase. "We're trying to quantify what media is adversely affected and what the pollution is, precisely," he explained. The other four are in a site investigation phase. "We suspect that we have a problem, but we need to gather enough data to make an informed decision." Two of the nine sites are in interim remediation, he said. "We already know they need some attention, and they're getting it, but the extent has not been established yet." Tinker has "a very mature environmental restoration program," and several such projects will be addressed over the next nine years, Mr. Aguilar said. "We have made significant progress toward cleaning up environmental contamination that occurred years ago," Mr. Bowen said. The base's environmental remediation staff is comprised of Mr. Aguilar, Mr. Bowen, and two environmental engineers; collectively they have worked at Tinker for 75 years, and all four had private-sector experience before coming to work at Tinker. The four are assisted by two contract support employees.