It shall be unlawful for any officer, agent, or employee of any utility company, permit holder (permittee), builder, developer, or contractor, who is in charge of any excavation and who, during such excavation, discovers evidence of or knows of a break or rupture in the containment system for natural gas or other flammable gas to delay making immediate notification of such condition to Public Safety Communications. It shall be unlawful for any person who discovers evidence of or knows of a concentration of natural gas or other flammable gas mixture within an enclosed structure or in the atmosphere to delay making immediate notification of such evidence or condition to Public Safety Communications. It shall be the responsibility of the excavator and/or contractor to have all overhead and underground utilities located before work commences.