Continued testing on PG&E's Line 132 is expected to cause traffic along Alma Street to be redirected for 10 days starting Jan. 18, City of Palo Alto Utilities spokeswoman Debra Katz said Tuesday morning (Jan. 17).

The work involves checking the outside casing surrounding the pipe for flaws. The 55-mile Line 132, which runs from Milpitas to South San Francisco, is the one involved in the San Bruno explosion and fire. The California Public Utilities Commission required PG&E to use hydrostatic (water pressure) testing to find leaks in the pipeline after the explosion.

Between September and November 2011, PG&E performed the tests on sections of the Line 132 pipe, which runs through Palo Alto. The pipe has been fully tested and was returned to full service in December, the city noted on its pipeline update page.

Related story: PG&E repairs leak in Palo Alto pipeline (Nov. 11, 2011)

The surrounding casing inspection would not cause impacts to service or any odors, Katz said. The main effect will be on commuters traveling southbound on Alma from Jan. 18 through Jan. 28. The work will be done between Alma and the Caltrain railroad tracks, just before the intersection with Oregon Expressway, Katz said.

Katz said commuters should consider taking alternate routes.

PG&E has three main transmission pipelines that traverse Palo Alto -- Lines 101, 109 and 132. Line 132 is the only one of the three pipelines required to be tested in PG&E's current hydrostatic testing project, the city noted.

Line 109 runs along Middlefield Road from Mountain View but then turns up East Charleston/Arastradero Road, continuing north along Foothill Expressway. It has had about two thirds of its length replaced in recent years and is believed to have been hydrostatically tested already but paper record verification of that is still underway, according to PG&E.

Originally installed portions of this pipeline -- running along Charleston between Alma and Middlefield -- are scheduled for replacement sometime between 2012 and 2014. That schedule is currently being prepared, according to PG&E.

Line 101 runs roughly parallel to Highway 101. All of the Palo Alto portions of this pipeline have been replaced since the requirement for hydrostatic testing was in place and there are validated records of passing this test, according to PG&E.

PG&E intends to install a permanent "in the pipeline inspection device" launching station on East Bayshore Road that will allow future regular, ongoing inspections. Construction of this device could start as early as summer of 2012.

PG&E's plans to repair or replace large sections of the nearly 12 miles of main gas lines in Palo Alto may end up taking years to complete, a top engineer told an inquisitive City Council Monday night.

That timeline was too long to satisfy Council Member Pat Burt, who with the rest of the council listened to hours of testimony from Todd Hogenson, director of PG&E’s Pipeline Safety Enhancement Plan (PSEP).

Hogenson gave a detailed account of the location, material composition, operating pressure, testing, and history of each of the three gas pipelines that run through Palo Alto, L-101, L-109, and the infamous L-132—the line that exploded in San Bruno last year, killing eight people.

An NTSB investigation found that explosion to be caused by a defective weld.

The PSEP was developed in the aftermath of that disaster and was submitted in August to the California Public Utilities Commission, which required all state gas utilities to draft such a plan.

Hogenson said that PG&E maintains 5,800 miles of pipelines in California, many of which were fabricated in the 1920’s and 30’s, long before the existence of modern pressure-testing tools. The first regulations on gas pipelines, he said, weren’t even drafted by the CPUC until 1961.

“Any pipelines installed before these dates were not required to be tested. They were grandfathered in,” he said. “We basically need to test all pipelines that have never been tested.”

The company plans to strength-test 165 miles of pipeline this year statewide, ramping up to 200 miles per year for the next four years.

PG&E designed a “decision tree” to prioritize which pipelines to inspect and repair or replace first.

The three lines in Palo Alto came up as a top priority given their proximity to dense population centers.

L-109, which is 4.64 miles long and was installed between 1936 and 2004, will have the entire portion that was laid in 1936—1.5 miles—replaced. That project is expected to take until 2014, which raised red flags for Pat Burt.

“Going into this session I was more concerned with Line 132,” said Burt, “and now I’m more focused on the segment of line 109 that basically runs between Middlefield Road and Alma Street.”

Burt pointed out that L-109 was of high enough concern to PG&E that they felt the need to replace it, but apparently not of enough concern to perform any hydrostatic tests in the mean time.

“What would it take to get hydro testing before 2013 on that line?” said Burt, who noted that Hogenson had just detailed four risk factors on L-109, including it’s old age, lack of prior pressure testing records, proximity to schools, and the fact that the seam running the length of the pipe is a “single-weld”.

PG&E’s policy, said Hogenson, is to not test lines that are being replaced.

“Is that really an adequate approach,” countered Burt, “if that’s our highest risk segment in the city?”

Hogenson admitted that the decision really came down to money.

“Right now we are spending more than $1.2 million for each mile to hydrotest,” he said, then packpedaled slightly, saying, “We think the pipeline is running safely. How is that pipeline gonna fail? What’s gonna cause that pipeline to fail? We’ve reduced the operating pressure in that pipeline.”

PG&E has, in fact, reduced the pressure.  L-109, a 20 to 24-inch pipe rated to  375 psig, had its operating pressure reduced 20 percent after the San Bruno explosion, along with both other main lines in Palo Alto.

Burt remained unconvinced.

“If it wasn’t at the risk level that you would consider replacing it, it would therefore not be at risk of failing,” said Burt. “You have lower pressure, and that certainly is a major factor, but it can fail. You can have a corrosion spot just like you did on 132. You and I both know that if you’ve got corrosion that turned up in one place, that’s a yellow flag that there could be corrosion in another place.”

Hogenson nodded and scribbled some notes onto his pad at the podium.

In addition to the pipes, PG&E also plans to replace old manual valves with automated valves that can be either controlled remotely from PG&E’s control center in San Francisco, or set to automatically shut off in the event of a dangerous pressure change.

These types valves are being installed on all three lines at points in Mountain View and near Sand Hill Road in Menlo Park.

Council Member Greg Scharff asked Hogenson what the effect of lower pressure is on the system as a whole.

Hogenson said that he is concerned that the lower operating pressure may lead to curtailments, especially if there are severe cold days this winter.

“We’ve never had curtailments in the San Francisco Peninsula for decades,” said Hogenson, adding that PG&E has warned “non-core rate customers” such as hospitals that they might have their gas service curtailed if indeed it gets too cold.

In the meantime, PG&E will continue to work with city staff and the CPUC to complete testing, repair and replacement of high-priority gas line throughout Palo Alto.

A natural gas pipeline that exploded during safety testing near Woodside Sunday afternoon (Nov. 6), causing a mudslide that shut down northbound Interstate Highway 280, had a pre-existing dent at the point where it ruptured, according to PG&E.

Pacific Gas & Electric was conducting hydrostatic pressure tests on a 3- mile section of the 24-inch transmission line between Menlo Park and Woodside at the time of the rupture, said utility spokesman Brian Swanson.

The tests involve emptying the pipe of gas and pumping water through at high pressure to check for any leaks or weak points.

The pipeline, Line 132, which runs from Milpitas to San Francisco, including through Palo Alto, is the same line that ruptured in San Bruno in October 2010, killing eight people and injuring many more. It normally operates at a pressure somewhere lower than 375 pounds per square inch but has been operating at a reduced pressure of less than 300 pounds per square inch, Swanson said.

"In order to help meet higher winter demands, we want to bring the pressure level back up to normal levels, around 375, but before we do that we need to ensure that the pipeline is safe," Swanson said.

Pressure in the pipeline had been raised to around 550 pounds per square inch at the time of Sunday's rupture, well above normal operating levels, he noted.

The rupture, which occurred around 3:20 p.m., was first reported as a large geyser of water that was getting cars wet on Interstate Highway 280 near Farm Hill Boulevard. A short time later an explosion was reported in the same area, along with a large volume of flowing water, according to Woodside Fire Battalion Chief Kevin Butler.

The rupture had caused a mudslide, sending mud, rocks and debris across the northbound lanes of the freeway. Several lanes on the freeway were closed by the slide, some for more than four hours.

There were no injuries, but one vehicle was damaged by pieces of dirt and rock, Butler said.

Fire crews located a 5 foot by 5 foot crater on the hillside east of the freeway, in an easement running behind a group of homes. The closest home was about 100 yards away, Butler said.

PG&E has tested around 120 miles of pipeline this year, Swanson said. Last week the utility found a 1 millimeter leak in Line 132 in Palo Alto, and last month a line ruptured in Bakersfield during testing. However, Sunday's rupture was far more disruptive.

"We'll definitely look into what happened today," Swanson said, noting that there were crews on the scene. "Obviously we don't want a hydrostatic test to disrupt traffic on 280 like it did today, and we will look at ways to minimize disruption."

PG&E will remain on the scene for several more days to make repairs and complete testing on the pipeline.

The PG&E gas-pipeline-testing project began with staging and excavation Thursday (Aug. 11) and will continue through late September, according to a schedule released by the City of Palo Alto Utilities department.

Gas line segments T-29 and T-30, which run through Palo Alto, will be vented of unused gas in order to conduct hydrostatic pressure-testing.

People in north Palo Alto can expect to smell gas on Friday, Aug. 19, when venting for pipeline segment T-29 will begin. T-29 stretches from Alma Street to Middlefield Road, with dig sites located at 2573 Alma, 3672 Middlefield and 3860 Middlefield.

Residents of south Palo Alto may notice a smell on Monday, Aug. 29, when segment T-30 will be vented. T-30 starts at the intersection of Alma and Page Mill Road and continues up Page Mill to Foothill Expressway. Dig sites are located at 650 Page Mill, 925 Page Mill, the corner of Page Mill and Hanover Street and 500 feet north of the intersection of Page Mill and Foothill.

Hydrostatic testing subjects pipes to water pressure 150 percent greater than the pressure allowed under normal gas use.

Tests will "validate a safe operating pressure for the pipeline" and hopefully "reveal weaknesses that could lead to defects and leaks," PG&E officials said last month. Weakened pipes will be repaired or replaced.

The testing schedule is as follows:

■ Friday, Aug. 19: Venting for pipeline segment T-29 begins (Alma Street to Middlefield Road); smell noticeable in Menlo Park and north Palo Alto

■ Thursday, Aug. 25: Hydrostatic testing of T-29 begins; air movers operate near Oregon Expressway and Alma Street, noise and slight smell noticeable

■ Monday, Aug. 29: Venting for pipeline segment T-30 begins (Alma and Page Mill Road, up Page Mill to Foothill Expressway), smell noticeable in Mountain View and south Palo Alto

■ Monday, Sept. 5: Hydrostatic testing of T-30 begins

After a delayed start date, PG&E will begin to prepare this week for testing its natural gas transmission pipeline that runs through Palo Alto, according to Debra Katz, acting communications manager with the City of Palo Alto Utilities Department.

Staging and excavation preparations will begin "possibly as early as Monday or Tuesday," Katz said. The project is expected to continue for two months.

Testing will not disrupt service, as an alternate source will temporarily provide all necessary gas, according to the Utilities Department website. But residents should expect to see above-ground signs of testing such as detours, traffic cones, testing equipment and machinery, as well as notice "noise and some gas smell," Katz said.

Last month, PG&E announced it would be conducting hydrostatic pressure-testing on its gas lines in order to "validate a safe operating pressure for the pipeline and ... reveal weaknesses that could lead to defects and leaks." Hydrostatic tests involve running water through the pipeline at a much higher pressure than it will ever operate with natural gas.

The pipeline is divided into two sections, known as T-29 and T-30. T-29 starts at Alma Street and zigzags south to Middlefield Road. T-30 starts at the intersection of Alma and Page Mill Road and goes up Page Mill to Foothill Expressway.

Staging and excavation will be carried out on both sections of pipe simultaneously, though T-29 will be tested first on Aug. 15 and T-30 "a week or two later," Katz said.

Dig sites for the T-29 section of pipe are located at 2573 Alma, 3672 Middlefield and 3860 Middlefield. Dig sites for T-30 will be located 500 feet north of the intersection of Page Mill and Foothill Expressway and at 650 Page Mill, 925 Page Mill and the corner of Page Mill and Hanover Street.

Twenty-nine areas of pipeline in the Bay Area, the Sacramento-San Joaquin River Delta area and the Monterey Bay area are included on PG&E's list, released Sept. 20, of its 100 highest-risk pipe segments. Click on the markers for details. The numbers correspond to map numbers on PG&E's list. For some longer segments, pipeline routes are approximately indicated, based on a map released by PG&E.

Follow the link to see an interactive map.

The city requested the following information:

■ A current map with precise locations of all PG&E high-pressure gas lines and other natural-gas facilities in Palo Alto, to be mailed by Sept. 23.
■ Updated information on the condition of the city's PG&E natural gas facilities.
■ Whether there are any high-risk gas-transmission facilities related to public safety in Palo Alto and where they are located.
■ Age of the pipelines and facilities
■ Size of the pipelines
■ Pressure at which PG&E typically operated the facilities
■ Whether PG&E has reduced the operating pressure recently. And what is the current operating pressure
■ Scope and date of PG&E's most recent pipeline maintenance activities
■ Frequency and nature of maintenance activities for all of PG&E natural-gas facilities in the city

A natural-gas pipeline running along Junipero Serra Boulevard in Stanford is on Pacific Gas & Electric Company's (PG&E) "Top 100" list of segments with greatest potential risk, according to a report released Monday by PG&E.

California Public Utilities Commission and Gov. Arnold Schwarzenegger had insisted PG&E release the "Top 100 Segments" report after a pipeline exploded on Sept. 9, creating an inferno in San Bruno that killed seven people, injured 50 others and destroyed 37 homes.

PG&E came under sharp criticism last week for not making the list public after it was disclosed that a portion of Line 132 near the explosion site had been identified as a high risk by PG&E in 2007.

No San Bruno portions of Line 132 were on the Top 100 list released Monday, however.

The aging natural-gas pipeline under investigation in the Sept. 9 San Bruno explosion and fire also runs through Palo Alto, according to a 2008 map from the California Energy Commission.

Known as Line 132, the 54-year-old pipeline runs down the Peninsula from San Francisco along the Interstate 280-Junipero Serra Boulevard corridor.

The line has not been replaced since its installation, PG&E spokeswoman Katie Romans said Friday.

Romans said the 30-inch steel pipeline was installed in 1956. The entire 51.5-mile gas line runs from Milpitas along California State Route 237 and Interstate 880 and ends in San Francisco at 23rd Avenue and Illinois Street, she said.

A 31.9-mile segment of Line 132 has been identified as needing retrofitting as part of PG&E's In-Line Inspection major capital-improvements projects for 2012, according to a PG&E report. It was not immediately clear if the Palo Alto segment is included in the 31.9 miles.

The risks and condition of Pacific Gas & Electric's (PG&E) aging natural-gas pipeline infrastructure on the Peninsula remain subject to speculation, despite numerous requests by news organizations for details about the age, size and maintenance and replacement schedules.

What is known about Palo Alto's gas system is that three PG&E transmission lines run through or near the city, including down portions of Middlefield Road, Oregon Expressway/Page Mill Road and Junipero Serra Boulevard, according to maps by the U.S. Pipeline and Hazardous Materials Safety Administration and the California Department of Conservation. PG&E owns and maintains those lines.

City of Palo Alto Utilities maintains the remainder of the gas system. That includes nearly 70 miles of steel gas mains that are 12 inches in diameter or smaller and approximately 1,152 miles of steel gas-service lines, Utilities Director Valerie Fong said.

During 2009, the department checked all 19,311 gas-service lines for leaks and did a mobile survey of 207 miles of city gas-main pipes, according to Greg Scoby, Palo Alto's engineering manager for water and gas.

The surveys found 75 main and 142 service leaks, which were repaired.

City of Palo Alto Utilities replaces every gas line in the city in 34.5 years (6 miles per year of distribution and 600 service lines); the average expectancy of such pipes is about 40 years, according to the city.