FacilitiesTransportation Highlights 2010 1109

Home

� - Prr �}' - 7 c74'F .R �r ' a ' y , , ,.. dN o+i" KreZin 'r��. \i'tk4f7 -• A.. }. # ; t or t , --r' r 41:.-S",. I a Ftls . t r : /0-I: . ,. r . #� , r 4 _ -1.' : 2 { q -, • Z t \ N. 42 d . r r r 2 _ r 2 F .- O t y .. sT} i [ t; +, t ,. r _r J t. ;# , aa4., # r • a [ r . 2 i r t' ` r { � r,z at t • *. t b -4 f 2 . .1 r .. } . ..r • tr \'V . # Y { i! "' _ ] h • !>> = F h a G- St-E fir �s i l a te rai l ' G , a s $ ys te� . t . y 2 ? 7 f`„„ , i- 4 2 t -. : � ;.13 .� a; D + a`a 4 . L a f .. ty: Z, ,per •, E - t ,`, . T .r -t .44 6:44.: s- ?ar st'. . ; _ .Xh, a gs t.' �. J t1i }i i. . 3 1 'tai"! .3- . • +). \: <_ .,�4�{�t.d;�...113. -.A.�i xt »t <. fG' ax)1,a:_'. PG &E operates an extensive natural gas system that serves customers from the Oregon border to the Bakersfield area. The system delivers gas to 4.3 million residential, commercial and industrial customer accounts in Northern and Central California communities. PG &E monitors its system constantly, 24 hours a day, seven days a week. Any threats to public safety are addressed immediately. Transmission • PG &E's natural gas transmission system comprises larger, high- pressure. mostly underground System pipelines that transport natural gas in bulk from out of state supply sources to customers connected . to our distribution system. • There are 6,438 miles of transmission pipelines in the PG &E system. • The system is divided into 20,000 pipeline segments, which typically are defined as the pipe located between two valves that control flow and pressure. • PG &E gas transmission pipelines range in diameter from 4" to 42 ". • Natural gas transmission pipelines in PG &E's system typically operate at pressures between 100 and 1040 psig (pounds per square inch gauge), depending on factors such as the size and physical characteristics of the pipeline. • Hundreds of automatic over - pressure protection control valves, installed where appropriate in the transmission system, protect pipelines from exceeding their maximum pressure design limits. • The transmission system serving San Francisco and the Peninsula originates at the Milpitas Gas Terminal. Sources of gas to Milpitas can be from northern supplies (Canadian gas), southern supplies (Southwest or Rockies gas), or storage. System • The Gas Control Center in San Francisco monitors PG &E's natural gas system at all times. Operations • Sensors along the natural -gas system feed information about pressure, flow rate and other operating information to PG &E's SCADA (Supervisory Control and Data Acquisition) system. • Data from SCADA along with other tools allows operators at the Gas Control Center to monitor the condition of all the major components of the system, and adjust pressure and flow rate within the system as needed. • In addition, the operators at the Control Center can shut down certain pipeline systems via remote control should the need arise. Inspections and • PG &E routinely conducts leak surveys and other field inspections of all our natural gas transmission lines. Maintenance • The surveys are designed to confirm the integrity of our transmission tines. Long -term • Engineers consider a number of factors such as: the potential for third -party damage to the line from planning activities like nearby digging or construction; the condition of the pipe, its specific design and physical characteristics; how close the particular segment is in relation to areas that may be prone to ground movement; and how close it is to a densely poputated or environmentally- sensitive area. • PG &E engineers assign values to each of these criteria and develop a weighted score for each segment. Each segment is then ranked, based on their score, from highest to lowest. Those with the highest relative rankings are included in a long -range planning and risk - management tool PG &E uses to help plan future activities and forecast anticipated long -term resource needs. • The data used in the assessment are updated regularly throughout the year to reflect the Latest engineering evaluations, field tests. hands -on inspections and maintenance work. That may lead to some segments moving down, up or off list. and others might move up. • This procedure is followed by almost every public utility in the country, and it's similar to the way any business plans for the future. 'RISE' M_v[ n ycdr Gas and Epclri[ Compsry, a wbvdury of PGaE Corprsdon. 0 2O;O P.cg.c Cas W Electric Company. AU rights revered.