Drilling below three thousand feet (3,000') shall be done with mud weighing at least 8.8 pounds per gallon. The hole should be kept full of mud at designated weight at all times until the producing sand is reached. The mud shall be weighed at such intervals as may be determined by the inspector. When withdrawing the drill pipe, the pipe shall be filled with mud after each eleven (11) stands have been withdrawn. Drilling the producing oil sand, however, may be done with oil in lieu of the use of any mud; provided, however, that if the oil is in circulation, such oil shall not be over 30-B gravity with a flashpoint of not less than three hundred fifty degrees Fahrenheit (350°F) and after being so used shall be by the operator turned into a circulation tank instead of into the pits. If, at any time, weight of such mud is less than that specified in this section, any inspector or officer of the city shall have the right to suspend drilling and all operations in or about such well until the weight of such mud complies with this section or the conditions of the oil shall be made to comply with the provisions of this chapter. (Ord. 1369 § 6H, 1979)