If there has been a leak or release from an underground storage facility or tank system or any part thereof which presents a potential threat to public health, safety or the environment or where there is any suspicion of soil or subsurface contamination, soil and/or groundwater samples from areas likely to have maximal amounts of contamination shall be obtained and analyzed for residual hazardous materials by an independent laboratory in a manner acceptable to the city. Information pertaining to the location of samples, sampling methods, test procedures, and test results shall be provided to the city no later than 15 days after the testing is completed. If there is any indication of soil or subsurface contamination, the permit holder shall be required to immediately initiate cleanup or decontamination operations and to demonstrate to the city that the condition no longer presents a threat of harm to the public health, safety or environment. If test results indicate the material is a hazardous waste, the matter will be referred to the Texas Natural Resource Conservation Commission and the city may take such other action as is authorized by this chapter or any other regulation or statute.