Water Authority-Cayman and Caribbean Utilities Company say the most recent tests of water the power company pumped into the North Sound shows no trace of petroleum pollutants.
Earlier tests had shown “possible trace presence of hydrocarbons” in samples of water discharged by CUC into the North Sound, as revealed in minutes from a Water Authority board and reported in Monday’s Caymanian Compass.
“This possible trace presence has also been detected in the ground water at CUC,” according to a statement released by CUC to the Compass on Monday afternoon. “CUC’s latest test results conducted within the last two months reported that there was no trace presence of hydrocarbons in the discharge into the North Sound.”
Under the abstraction and discharge licences issued by the Water Authority to CUC, the electricity company is required to report any contamination of hydrocarbons or toxins in the water it is allowed to pump into the North Sound. The permit allows CUC to discharge up to 12.7 million gallons of water a day into the sound, at a maximum temperature of 107.6 degrees Fahrenheit (42 degrees Celsius) and stipulates “no chemicals, toxic or harmful substances to be added”.
The Water Authority granted CUC the licence to discharge the water from wells at the power company’s plant into the nearby North Sound in June last year. Six months later, CUC notified the authority that low levels of petroleum hydrocarbons had been detected in the discharge, minutes from a 18 April, 2012, Water Authority board meeting, released under a Freedom of Information request, revealed.
The week before Easter, CUC provided test results of water samples from six wells that cool its generators, which “confirmed the presence of low level petroleum hydrocarbons in four of the six supply wells that had been tested,” the minutes read.
According to CUC, tests done during the last two months show that levels of hydrocarbons found were below the minimum quantifiable limits of 3.9 parts per million.
Having consulted the independent laboratory that conducted the tests and the Water Authority and Department of Environment, “it is possible that these results are false positive results based on the very low level of results and being below the minimum quantifiable limits of the test”, the CUC statement read.
“Based on this information and ongoing discussions with the Water Authority and DOE, there has been no information that would confirm the presence of hydrocarbon above the minimum quantifiable levels to determine any negative environmental impact. However, CUC continues to monitor this issue and will continue to discuss the results of the testing with the relevant government authorities to ensure the ongoing protection of our environment,” the company statement read.
Petroleum hydrocardons are chemical compounds that originally come from crude oil.
CUC has continued to discharge the water, which is used to cool the power company’s generator engines, into the sound while retesting the water and reviewing the situation.
Hendrik-Jan van Genderen, water resources engineer at the Water Authority, said there was uncertainty about the positive result of hydrocarbons being found in the tested water and that the lab method and quality assurance and quality control procedures of the lab were being reviewed.
“The original samples were composite samples of all cooling water that is discharged. CUC has carried out further sampling of the source of cooling water and discharged cooling water for individual generators to determine whether a positive source could be identified, e.g., a contaminated well or a generator that may have a problem.
“There were some positive results, which were between the analytical method detection limit and the practical quantitation limit. Some of the results for individual feedwater sources were positive for TRPH (total recoverable petroleum hydrocarbons), whereas the discharged water from the same unit had a non-positive result. This shows that we cannot conclude with certainty that CUC is discharging hydrocarbons into the Sound.”
Mr. van Genderen said that under the terms of the discharge licence, CUC was also required to monitor the discharged water for benzene, ethylbenzene, toluene, xylenes, known collectively at BTEX, and methyl tertiary-butyl ether, known as MTBE, which are specific compounds of hydrocarbons. Benzene is a chemical of concern due to its carcinogenicity, he said.
“None of the samples taken from cooling water had positive results for BTEX and MTBE. It should be noted that the analytical methods for BTEX and MTBE detect in the parts per billion range, whereas the testing for TRPH detects in the parts per million range, so testing for BTEX detects at a level of approximately 1,000 times lower than TRPH,” Mr. van Genderen said.
Under the terms of the discharge permit, CUC is required to carry out annual testing of discharged cooling water for 126 pollutants, as per United States’ Environmental Protection Agency. Mr. van Genderen said this test has been carried out and the results indicate no presence of these pollutants in the cooling water discharge.