a danger to public health. The leaks originated from two buried pipes that had not been properly insulated when they were last worked on in 1991. A second leak was discovered in August 2009, from a pipe leading into an electrical turbine building. Tritium levels found in this leak were measured at 10 microcuries per liter of water, higher than the 5 to 6 microcuries per liter found in the earlier leak. Tritium-contaminated groundwater remained on site and had not spread to any public water supplies. In May 2010, the New Jersey DEP announced that water from the leak had spread to a nearby aquifer, though it stated there "was no imminent danger" to water supplies. At the current rate of migration, the water will reach the closest public wells within 10 to 15 years. The DEP stated there are several ways to address the problem, such as pumping out the tainted water, or injecting fresh water to force the tainted water backwards. A spokesman for Oyster Creek said they are working with the state on the issue, and have seen contamination levels steadily dropping, sometimes by "as much as 90%". Tritium causes less concern than other radioactive substances such as strontium, caesium and iodine. It does not bio-accumulate inside human tissue. Safety Employees at the Oyster Creek nuclear power plant averaged less radiation exposure from 2005 through 2008 than workers at any other nuclear power plant of similar design in the United States. In early May 2011, fuel supplier General Electric notified the operators of the Oyster Creek and Nine Mile Point nuclear plants regarding safety calculation errors. General Electric had made mathematical errors which could have resulted in nuclear fuel getting hotter than operators expected, reducing the plants' margin of safety. Plant operators were able to make corrections. Hurricane Sandy On October 30, 2012, during Hurricane Sandy, the nuclear power plant's intake structure was flooded with six and a half feet of water as a result of the storm surge from the hurricane, with no damage sustained, and at the same time the plant was already down for maintenance and lost its electrical power from the grid, so operators called an alert that escalated the plant a step up from the lowest emergency level, and turned to backup generators to keep cooling the reactor. In following months, local residents continued to voice their worries despite a statement by