Grease interceptors/traps shall be located close to the grease-laden wastewater source and cleaned at or before the grease layer depth reaches seventy-five percent of its effective total liquid depth. The operator of a grease interceptor shall maintain a log book of all maintenance activities and evidence of grease disposal in accordance with the city regulations. Grease interceptors/traps shall be subject to unannounced inspection by the city at any time during their operation. (Ord. 1485-95 § 2(part), 1995).