Underground utilities must be properly located, installed, and protected to prevent damage. Utility locating services mark all existing utilities before excavation. Locate marks are typically color-coded: red for electrical, yellow for gas, blue for water, green for sewers, pink for telecommunications, orange for misc. Minimum clearances must be maintained between utilities to prevent damage if one is disturbed. Electrical lines must be buried at least 18 inches for residential areas, deeper in commercial areas. Gas lines must be buried 30 inches minimum in most areas. Water lines must be below frost line to prevent freezing. Separate trenches prevent conflicts and allow independent maintenance. Conduit or other protection is used for electrical lines and telecommunications. Conduit protects the lines and allows replacement without re-excavation. Bell holes (wider sections) allow routing around obstacles. Valve boxes mark water shutoff locations for emergencies. Cleanouts mark sewer access points for maintenance. Pressure testing of water lines verifies system integrity. Gas lines are tested at lower pressure but still thoroughly. Electrical testing verifies insulation integrity. After testing, permanent identification is installed. Pavement must be patched after trench closure. Compaction in stages ensures proper density. Final pavement provides a durable surface. Location records are critical for future work; utility maps document all lines. Updated records prevent accidental damage during future excavation.