Complex sentence: MacKay noted that the project has resulted in substantial testing of ground water around the plant, however he noted that because there are no standards for CO 2, it was impossible to say that the plant would create a pollution problem with its massive CO 2 emissions.
Split into simpler sentences: MacKay noted that the project has resulted in substantial testing of ground water around the plant. He also noted that because there are no standards for CO 2, it was impossible to say that the plant would create a pollution problem with its massive CO 2 emissions.