PG&E resumed pressure testing Thursday on a 4-mile section of natural gas pipeline between Menlo Park and Palo Alto where a small leak was detected late last week, a utility spokesman said.

Crews had been performing hydrostatic pressure tests -- in which the pipeline is cleared of gas and filled with water to detect weaknesses -- on a portion of Line 132 between Sand Hill Road and Page Mill Road, when a pin-sized leak measuring 1 or 2 millimeters was located near Hanover Street in Palo Alto, PG&E spokesman Brian Swanson said.

Repairs were completed Wednesday morning, he said.

"We welded a steel band around the pipe and over the pinhole," Swanson said. "The steel band acts as a protective barrier."

Crews resumed hydrostatic testing Thursday afternoon to determine if there are any more weaknesses on this portion of pipeline.

Last Sunday, pressure testing on a 3-mile portion of Line 132 near Woodside caused a rupture that sent water from inside the pipe down a hillside above Interstate Highway 280.

Mud and water blocked two lanes of the highway for more than two hours.

PG&E investigators determined that the pipe had been damaged by construction equipment, Swanson said.

Crews were continuing to inspect the area around the rupture to see if any other damaged portions could be located.

"Repairs on that section are still ongoing," Swanson said.

A faulty seam on Line 132 ruptured in San Bruno on Sept. 9, 2010, causing an explosion that killed eight people and destroyed 38 homes.