If you’ve made a trip to the new Fresh & Easy market on Silver and Goettingen, you probably have had to navigate around a big hole on Felton St. A mass of PG&E equipment has accumulated there over the past few weeks. Directly affected citizens of the Portola who live in the area were notified of the work by PG&E, but the Portola Planet has enquired to bring everyone some information on what’s going on.
As a result of the horrific accident in San Bruno in 2010, PG&E has been testing pipelines for problems. The process they use is called Hydrostatic Pressure Testing and involves removing the main pipe from general service, filling it with water and then raising the pressure while looking for leaks.
The tests are done on the major transmission lines which bring gas into the city and run all over the bay area. They are massive pipes and usually contain the gas at a maximum pressure of 390 psi. However during the testing phase, they maintain a pressure of 605 psi for up to 8 hours. During these tests local customers have their gas supply re-routed from other lines to avoid disruption to service.
Three main big pipes feed the city, two of which run through the Portola. One coming in down Hamilton St which turns down Felton. The other just skirts our neighborhood as it follows Bayshore Boulevard. The pipe running down Felton, is at one end of those tests, which will be taking place for at least the next few weeks. What do they actually do? The PG&E website reveals the following;
Performing a hydrostatic test involves the following steps:
- PG&E obtains all required work permits and coordinates activities with local agencies.
- Gas is temporarily provided to customers from an alternate source.
- The section of pipeline to be tested is temporarily removed from service and safely vented of all natural gas.
- The inside is mechanically cleaned prior to testing.
- The section is sealed on both ends and filled completely with water.
- The pipeline is pressurized to a specified pressure greater than normal operating pressure.
- The test pressure is held and monitored for a set period of time, typically 8 hours.
- Any pipe sections that do not meet acceptable standards during the test will be replaced with new pipe that has already passed a pressure test.
- Following a successful test, the section of pipe is emptied of water, dried thoroughly and placed back into service.
So while this is causing disruption to the flow of traffic around the area, it does mean our gas system should be safer for us all.