City of Palo Alto Utilities Department. Gas System Overview with special focus on Barron Park (updated after 11/30/11 community meeting)

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1 City of Palo Alto Utilities Department Gas System Overview with special focus on Barron Park (updated after 11/30/11 community meeting)

2 Natural Gas Facts Odorless and non toxic 95% methane (CH 4 ) Only combusts if concentrations are between 4 15% of gas in air Odorant is added at a level of 10% of LEL (lower explosive limit) or 0.4% of gas in air (4000 ppm) Domestic supplies projected to last over 100 years at current consumption levels

3 Natural Gas Safety Applies to all residents, everywhere in the City, all the time Smell gas inside? (similar to rotten eggs/sulfur) leave your residence immediately do not turn off appliances do not use your phone until a safe distance away using cell or neighbor s phone, contact CPAU (or call 911) Utilities crews will investigate and conduct repairs Signs of gas outside? (high pitched hissing noises, dirt blowing, water bubbling or discolored vegetation) leave the area immediately and contact Utilities at (or call 911) Utilities crews will investigate and conduct repairs Need to dig? Call first! Dial 811 (USA Underground Service Alert) to have underground utilities marked Q: How do you know where pipelines are located? A: Maps, plus we have detection devices to locate when no good map records exist. Colored marks you often see on streets & sidewalks are USA Correct Alignment Have a sewer blockage? Call Utilities first! Dial so the City can check your sewer line for potential crossbores Q. Are the homes that might have crossbores congregated in one area of town? A. No. And there are very few of them so far, out of ~2,ooo sewer laterals checked, only one sewer gas crossbore was found, and it was way back on the property near in in law quarters. Full details are at the city website: Crossbore

4 Palo Alto Gas System: Key Facts Founded in ,000 meters 205 miles of mains (2 12 ) mains are the city s gas lines in the street 18,000 service lines (1/2 6 ) service lines go from the main to your house s gas meter. Maximum System Operating Pressure: 25 psi* on our distribution lines (*pounds per square inch) inside your home, gas pressure 2 psi PG&E typically operates at 60 psi Four delivery gate stations where we receive gas from PG&E transmission system Map Color Key: Yellow Polyethylene materials Blue Steel pipes (a.k.a. black wrap ) Green ABS pipes Pink PVC pipes (info accurate as of 11/11)

5 Pipeline Safety & Maintenance Ongoing cathodic protection monitoring Applies to metal portions of system Uses electrical wires to draw corrosion away from pipe Leak detection the best method to find problem materials Federal Dept of Transportation requirement only requires leak surveys every 5 years Utilities Dept goes way beyond that requirement: half the system surveyed annually (walking) entire system surveyed annually (mobile) high tech detection equipment on vehicle uses light and air samples instruments detect as little as ppm depending on technology ppm = parts per million Types of detectors: flame Ionization, Combustible Gas Detector survey results are the basis for decision each year as to which system component s should be replaced Image of walking leak survey being conducted, courtesy of Goudy Engineering, Inc.

6 Q&A from 11/30 meeting: Leaks & Pipe Strength Q. Why are there any leaks in Palo Alto at all? A. Any type of pressurized gas system is going to have leaks. There is simply no such thing as a leak proof system anywhere in the world. What is critical to operating a safe system is monitoring the pipelines and detecting leaks. When found, leaks are graded based on their location and size. Some leaks are considered so minor by the regulators that you have 2 years to fix them, although our Utilities Dept fixes them right away. Q. What about the effect of earthquakes? A. The state of the art polyethylene we now install (TR418) is elastic and handles earthquakes well (e.g. none of this pipe cracked during the Loma Prieta quake). Q. How strong are the pipes where they re welded together? A. The welded joints are actually stronger than the pipes themselves. We test all of our pipeline installers responsible for fabricating polyethylene gas main and service connections on their welding or fusion processes to ensure that they are qualified to perform this work. Qualification of these workers includes basically, taking pipes they ve welded or fused and pulling on them with destructive force there must be permanent deformation of the pipe PRIOR to the joint failing, which indicates they have successfully made the pipe joint stronger than the pipe itself. Q. What about the pipes themselves? A. All our new pipelines are tested for 24 hours at 100 psi, which is three times higher than we are required to do by law. (25 psi is our actual maximum operating pressure.) Also, starting in 1999 we took it upon ourselves 10 years before regulators required it to install excess flow valves (EFVs) on all new gas service lines. These EFVs sense when too much gas is flowing (i.e. a leak) in the City owned service line and automatically shut down flow in this pipe.

7 Gas System: Capital Improvement Program 1992 Aggressive main replacement program put into place Replacements accelerated to 4 miles/year 1996 Replacement pace increased 6 miles/year Since 1992 we have replaced ~ 50% of system replaced all new below ground installations with: medium density polyethylene (TR418) Flexible, strong material that as yet has never failed industry tests so has no life expectancy limit installed via horizontal direction drilling (tunnel underground rather than trench above ground) when possible. annual construction costs: ~$6 million each year targeted pipes and parts of system associated with leaks Gold on map indicates pipelines now replaced with TR418 polyethylene. (map info valid as of 11/30/11) Q. How deep are the pipelines buried? A. Mains are buried at ; service lines are buried at 18 and also, fyi, water lines are buried at 36

8 Gas Main Replacement Project Description typically ~ 6 miles of mains and 600 service lines replaced annually new parallel system is installed all system components replaced little or no customer disruption of gas service horizontal directional drilling minimizes surface disruption (to street pavement and customer owned landscaping) construction duration averages ~ 300 days typical, 3 weeks per typical City block notification sent to customers at start of project 7 days prior to activity in a specific area 24 hours before start of work construction includes street restoration and surface improvements new pipelines go into service only after passing a leak free pressure test 100 PSI for a minimum 24 hour period Recent horizontal drilling to place gas line crossing HWY 101

9 Gas System Pipeline Replacement Strategy Replace targeted materials reaching end of their useful life those portions of system with elevated maintenance history more problems with leaks metallic portions of system with problematic cathodic protection Coordinate replacements with pending improvement projects with other paving activity Increase system capacity to address future loads increase system reliability

10 Barron Park Gas Distribution System Former PG&E gas system Acquired 1975 when Barron Park was annexed into City 68,750 ft of gas mains Staff researching composition based on PG&E records October 2011 additional leak survey conducted on identified Aldyl pipes in Barron Park no leaks found (info on slide is accurate as of 11/29/11) Barron Park Material Inventory (color code indicated) Steel 43,643 ft (63%) ROYAL BLUE PVC 4,581 ft (7%) RED ABS 1,599 ft (2%) LIGHT BLUE Polyethylene (TR 418) 11,689 ft (17%) YELLOW Polyethylene (Aldyl) 7,232 ft (11%) PINK

11 Aldyl Pipeline Material Like TR418, also a medium density polyethylene material manufactured by DuPont different in quality, however, from medium density polyethylene resin Palo Alto installs (TR418) Between1965 and 1985 was installed by PG&E throughout their territory some defective Aldyl material manufactured for brief period in early 70s that cracks more easily Aldyl associated with recent incidents in Roseville and Cupertino that you may have read about. Palo Alto has not experienced leaks associated with this Aldyl material However, due to recent incidents outside of Palo Alto, replacement of this material in Barron Park will be included in the next annual gas main replacement project Currently in design phase, the construction phase of gas main replacement project is projected to start in summer 2012 Q. Can you tell which Aldyl pipelines in the ground are defective and which are not? A. Our records associated with this area unfortunately do not indicate the type of polyethylene. The only way to make sure (type of polyethylene) would be to excavate and expose these pipelines for positive verification. Rather than doing this which would be a disruption to our customers in these areas and then returning again later this year to replace some of the Aldyl facilities, our current plans are simply to replace all Aldyl mains and services in our next gas main replacement project currently being designed. In the meantime, we will continue to monitor these areas with frequent leak surveys and conduct repairs on an as needed basis until these facilities are replaced. Based on our most recent leak survey of Barron Park in October, no leaks have been found associated with any of the polyethylene pipelines.

12 Upcoming Gas Main Replacement (Project 19B/20) will finish replacement of all Acrylonitrile Butadiene Styrene (ABS) mains in the City replacing all ABS was the goal of the accelerated replacement program started in 1992 black lines on map at right will combine two years of projects into one to replace a total of ~70,000 ft of pipeline, including Aldyl pipeline in Barron Park engineering design now in progress construction kickoff summer 2012 Q. How do people know their pipelines are safe between now and when they are replaced? A. Gas leak surveys where pipes are checked all the way to each home s meter are being conducted in Barron Park every 6 months.

13 Final Miscellaneous Qs & As from Meeting Q. What is the Utilities Dept s role in the PG&E transmission pipeline testing that has been going on in Palo Alto? A. We have supported PG&E efforts to conduct this critical testing and altered our operations accordingly to facilitate timely completion of these activities. While, the City is not in a position to take the role of inspecting transmission line testing and repair work, there are 3 rd parties appointed by the state who are doing just that. Q. What about PG&E s replacement of line #109 along Arastradero? A. The section of this transmission pipeline that PG&E plans to replace is actually about a half-mile long stretch of Charleston between Alma and Middlefield. This section represents one segment out of about 189 miles of pipeline statewide that is old and needs replacement over the next 2-3 years. Staff is working with PG&E right now to encourage the replacement in our territory as soon as possible. Meanwhile, PG&E is operating the pipeline at a lower pressure and monitoring it for leaks. Q. When will the Matadero Well site be finished? A. The well is scheduled to be operational by the end of the year. Associated site condition restoration efforts will completed by May The well retrofits are part of our larger Emergency Water Supply system upgrade project and you will see other components of this project happening all over town in the coming months/years. For full details, visit our website at

14 Contact Information For additional information, updates or to ask questions, please contact: Debra Katz, Utilities Communications Manager (650) If she can t provide all you need, she ll find the right person who can! The presentation above was originally given to Barron Park residents by: Greg Scoby, PE Water Gas Wastewater Engineering Manager City of Palo Alto Utilities With additional input from: Dean Batchelor, Assistant Director of Operations, City of Palo Alto Utilities