Flying manholes cause headaches in U.S. capitalgreenspun.com : LUSENET : Grassroots Information Coordination Center (GICC) : One Thread
Flying manholes cause headaches in U.S. capital
WASHINGTON (Reuters) -- As if rats, potholes and crumbling schools were not problems enough, the U.S. capital this week grappled with the latest recurrence of a bizarre case of flying manhole covers.
Residents and business owners in the Georgetown area fumed Friday in snarled traffic and sweltered in summer heat after a manhole fire knocked out power to hundreds of businesses and homes.
The fire, which started in underground electric cables Wednesday afternoon and sent smoke billowing from about a dozen manholes, follows a series of cases over the last 18 months in which pedestrians in the upscale shopping district have been startled by the heavy metal disks unexpectedly popping several feet up into the air.
The other cases of flying manhole covers have also been blamed on subterranean fires, the local utility Pepco said.
While no one appears to have been hurt, the flying manhole covers have become a major headache for officials struggling to promote the city as business-like and efficient after years of being tarnished with a reputation of being bankrupt and crime-ridden.
"This is a disaster, basically," Christian Furin, the manager of Furin's gourmet cafe, told Reuters inside his darkened eatery on M street, the district's usually bustling main drag of trendy shops and boutiques.
Police tape and orange traffic cones blocked the road to traffic for the third day in a row on Friday as utility trucks and police cars with flashing lights stood at intervals along the street and technicians in hard hats peered down manholes.
Rented generators rumbled on the sidewalk outside the Four Seasons Hotel. Restaurants and other shops were darkened and empty at Friday lunch.
"We've lost all our food. We had to throw it away. And we had to cancel a couple of parties we were catering," Furin said, estimating the cafe's losses as $40,000 so far.
For years, complaints in Washington have focused on potholes, rampant rats and dilapidated schools under the charismatic but controversial former Mayor Marion Barry.
Mayor Anthony Williams, who has presided over an urban renaissance and prides himself on record rates of pothole filling, took to the streets himself Thursday to soothe irate residents.
Pepco last month announced a three-year, $30 million rewiring and reconstruction program for Georgetown, which it says has the oldest wiring and infrastructure in the city.
But it comes too late for the 1200 residents and businesses who have been living for three days without refrigerators, light or air conditioning in sweltering summer temperatures.
"It's terrible for us," fumed Joe Tauscher, sweating outside the Mes Amis restaurant which he bought one month ago with his father Bill. "We had just started to pack our place (with diners) and now you wonder what's going to happen when you open your doors again."
Copyright 2001 Reuters
-- Martin Thompson (email@example.com), June 15, 2001
Seems to be a summer problem. From the archives
Pepco Told to Prepare D.C. Manhole Strategy
By Petula Dvorak Washington Post Staff Writer Saturday, June 17, 2000; Page B02
The D.C. Public Service Commission ordered Potomac Electric Power Co. yesterday to develop a comprehensive plan to diminish the District's problems with flying manhole covers and to report all underground incidents.
-- Martin Thompson (firstname.lastname@example.org), June 15, 2001.
This has been going on for the last 18 months. Hmmm. This is the time since Rollover. Could Y2K have anything to do with this infrastructure disruption problem?
Y2K observer Cory Hamasaki has been citing this problem for about the last 17 months, on his "D.C. Y2K Weather Reports" site and Email list. Website: http://www.kiyoinc.com/current.html
-- Robert Riggs (email@example.com), June 16, 2001.
The following excerpt is from 1/30/2001 Summary of an Engineer's Observations Regarding the Status of Ongoing Y2K-Related Embedded Systems and Complex Integrated Systems Problems Compiled by Paula Gordon (With a minor revision made 2/1/2001) http://www.gwu.edu/~y2k/keypeople/gordon/EngObs.html
It pertains to the possible causes of manhole cover explosions. "..I asked [the Engineer] what he thought about the possibility that manhole cover explosions might be caused by irregularities in transmission. He said that the manhole issue is a very interesting one and that he feels that it is due to electrical power cables overheating and creating a gas that results in an explosion. He thinks that this is probably due to the use of manual power overrides..."
If there are other engineers reading this who have knowledge of these matters, I hope that they will post here or contact me directly, on or off the record.
-- Paula Gordon (firstname.lastname@example.org), June 16, 2001.
Another manhole cover explosion and fire today. This one in Chevy Chase, Maryland at the District/Maryland line.
Since I last posted to this thread I have talked with another engineer who says that the "Engineer's Observations" (quoted above) are plausible, that spiking could occur if manual overrides are being used and that spiking could precipitate explosions in worn cables.
Any other engineers have an opinion to offer on this?
-- Paula Gordon (email@example.com), June 29, 2001.
DC - Short in cable cut power By Robert Treadway THE WASHINGTON TIMES
A smoldering underground cable left about 300 Columbia Heights customers without power until early yesterday afternoon when Potomac Electric Power Co. completed repairs.
Yesterday's short of a 14,000-volt primary cable was most likely heat-related, said Robert Dobkin, Pepco spokesman. The outage affected mainly residential customers between 14th and 16th streets and Park Road and Newton Street NW. The smoke came from a manhole in front of 1413 Park Road NW, but service was disrupted in a residential area several blocks away. Service was restored around 1:12 p.m. This smoldering manhole was the first in the Columbia Heights area in recent years, although a series of manhole explosions have plagued other parts of the city, most notably the Georgetown area. Almost two weeks ago, an underground fire left 1,600 Georgetown customers without power for four days in the neighborhood around M Street NW. City officials said that blackout cost businesses more than $1 million. Yesterday around 9:30 a.m., a police officer called the D.C. fire department to report smoke coming from a manhole. Fire department officials then notified Pepco of the problem and work crews were immediately sent to the site. When they arrived, they found no evidence of an explosion and saw no flames coming from the manhole. Mr. Dobkin said Pepco received calls from several customers in the neighborhood in the past few weeks saying their lights had been flickering, but workers have been unable to isolate the problem. He said a hole in the insulation the size of a pinhole could cause the lights to flicker, adding that blackouts often occur. "We have minor outages frequently," Mr. Dobkin said. "It is part of having a major metropolitan system." He said temporary repairs in Georgetown have been completed at 31st and M streets NW. Pepco crews last week repaired several sets of cables that intersect at the corner without any customers losing power. All Pepco equipment has been removed and all lanes have been reopened to traffic. Work crews will return soon to do permanent repairs. An overhaul of the underground utility network, including electric, phone, water and gas lines, is scheduled to begin in August, Mr. Dobkin said.
-- Doris (firstname.lastname@example.org), June 29, 2001.
No Connection Seen in Power Disruptions Chevy Chase Manhole Blast Unrelated to Georgetown Woes, Pepco Says
By Phuong Ly and Jo Becker Washington Post Staff Writers Saturday, June 30, 2001; Page B01
Power company officials yesterday blamed a short circuit for Thursday's manhole explosion in Chevy Chase, and they emphasized that the blast was not related to the large-scale wiring problem that shut down Georgetown this month and is forcing the replacement of the underground power network there.
The blast Thursday prompted the evacuation of the Chevy Chase Shopping Center and forced Potomac Electric Power Co. to shut off electricity to thousands of customers for several hours. Power will not be restored to the shopping center until sometime today, said Nancy Moses, a spokeswoman for Pepco.
Flames and smoke shot out of the manhole in front of the CVS drugstore at 21 Wisconsin Circle, but no one was injured, said a Montgomery County fire department spokesman.
Pepco crews spent yesterday replacing cables under the shopping center. Moses said even undamaged cables were being replaced "to give everyone peace of mind."
Cracks in cable insulation may have caused the explosion, Moses said. Cracks could have been caused by defective manufacturing, a rodent or stress on the line, she said.
"Mechanical equipment can fail," Moses said. "This is a large, complex delivery system of electricity. We have 67,000 manhole covers. We have 25,000 miles of overhead and underground cable."
Still, for local government officials, the Georgetown power problems loomed large.
Montgomery County Fire Administrator Gordon Aoyagi sat down with a Pepco official June 12 and asked how likely a power outage like those that were plaguing Georgetown would be in Montgomery County. (The next day, Georgetown was hit with a power failure that crippled much of the business district for about three days.)
Aoyagi heard a reassuring message. "A lot of redevelopment has occurred . . . and when redevelopment happens, they take an opportunity to upgrade their equipment, so they indicated that the possibility of something happening here was very remote," he said.
County officials plan to meet next week with Pepco officials to find out what happened Thursday in greater detail. They also have ordered a risk assessment to see what the county can do to prevent such incidents.
"This is not an issue that is isolated to the Georgetown community now," said David Weaver, spokesman for County Executive Douglas M. Duncan (D). "We need to get answers."
Businesses spent yesterday trying to minimize their losses.
"What a mess," said Barry Scher, vice president of public affairs for Giant Food Inc., the Chevy Chase Shopping Center's largest tenant. After the power went out, the company brought in a tractor-trailer carrying a large portable generator. By 1 a.m., the store was powered up.
The store opened at 8:15 a.m., and shoppers weaved through a cordoned- off pathway as Pepco workers dug up burned cables.
"A lot of seniors come to that center -- it's a daily event for them - - so that's why we wanted to open it," Scher said.
Other stores in the shopping center, including Blockbuster, CVS and Marvelous Market, were closed yesterday and not expected to reopen until at least today.
Marvelous Market employees were preparing to bake bread and assemble sandwiches and salads when the power went out. With dough rising and nowhere to bake, the chief executive of the upscale nine-store chain rented trucks and shuttled the food to other stores.
"Bakers worked feverishly all night to catch up," said CEO Michael Meyer, who estimated his losses in the tens of thousands of dollars. "The deliveries went out late today, and our customers weren't happy. But there wasn't much we could do."
Pepco has invited businesses to file claims with the utility, but Meyer said he was worried that not all his losses would be covered.
Residents were inconvenienced as well. Most people in the area are senior citizens living in high-rise apartment buildings. Dozens of people were rescued from elevators that were stuck when Pepco shut off electricity, said Pete Piringer, a fire department spokesman.
A property manager of one building said some people walked up as many as 17 flights of stairs to their apartments. "You don't know how much you take for granted until it happens," said the property manager, who spoke on condition that she not be identified.
-- Martin Thompson (email@example.com), June 30, 2001.
Thanks, Martin, for the posting the article on the Chevy Chase incident.
-- Paula Gordon (firstname.lastname@example.org), July 02, 2001.
Here is one from Mass that I missed.
Manhole fire cuts downtown power
Tuesday, June 19, 2001 By BETSY CALVERT
GREENFIELD — An explosion under Federal Street yesterday morning knocked out downtown power for four hours, blew a cast-iron manhole cover into the air and lifted up a car with its passengers 1½ feet.
City emergency workers rushed to the scene just before 8 a.m. and discovered burning wires under the street near the Greenfield Savings Bank. The cause is presumed to be electrical.
The repair crew from Western Massachusetts Electric Co. at first feared power would be out all day. The crew decided on a technique, however, that would return power much sooner, said company spokeswoman Denise Vogel. They expect to remain on the scene for several days working on a complete repair, she said.
The exact cause of the explosion is still unknown. After the explosion, the electric company soon discovered two problems, Vogel said. A main cable failed causing a loud, popping noise. Also, a secondary cable was burning in the same area, causing the underground space to fill with odorless carbon monoxide. Electrical repair workers were forced to wait several hours before examining the problem.
Bystanders reported more than a popping sound.
"It felt like a truck had smashed into the building," said Denise A. Coyne, senior operations officer at Greenfield Savings Bank. The explosion also broke a window in a nearby apartment building, she said.
Town Councilor Kenneth G. Willis, taking advantage of Boston's day off for Bunker Hill Day, was still asleep when the explosion sounded outside his window. Objects fell off the shelves in his apartment, he said, and he felt as though he were knocked out of bed.
At ground zero, the 63-year-old manhole cover broke into many pieces, most of which fell into the hole under the street.
Yamara C. Clark of Greenfield and her former husband, Keith R. Gallagher of Chicopee, were driving an old Subaru north on Federal Street, just a few feet from the manhole when it blew up, lifting the car in the air.
The experience was truly unnerving, Clark said, adding that she was grateful they were wearing seat belts.
"I started having a panic attack," she said, immediately after the explosion. Fortunately, she was carrying her anti-anxiety pills, so she swallowed one, only to notice then that her neck hurt badly.
Both she and Gallagher were treated and released from Franklin Medical Center.
Not all businesses lost power. Wilson's Department Store had power, but neighboring Greenfield Community College's downtown offices lost power.
Bogey's Sandwich Shop stayed open despite the power loss, because the gas grills still worked. The eatery ran out of caffeinated coffee quickly, however.
And when the power returned just before noon, its staff was not ready for lunch, but labored to serve the masses that poured in, anyway.
No power was no big deal to music store, About Music. Customers browsed the CD racks in filtered summer sunlight.
"Watch me make change without benefit of electricity," store manager Matthew Kim bragged to a customer.
Vogel said she is expecting a more detailed explanation within a few days.
-- Martin Thompson (email@example.com), July 02, 2001.
Very interesting comments from Joseph Whaley on a related thread on TB2K at http://www.timebomb2000.com/cgi-bin/tb2k/ultimatebb.cgi? ubb=get_topic&f=1&t=002279
He notes that "....while PEPCO's generating equipment had few components with Y2K issues, their engineer in charge of Y2K admitted to me that they did find several percent of their equipment in need of attention. Evidently they did a very careful and through job, and fixed what they found. Did they find everything? If not, would they admit it? Especially this late?....." (End of quoted excerpt) This comment reminded me of an article in the August 3, 1998 Los Angeles Times. Here is what that article said: "Eric Trapp, head of the year 2000 program for Southern California Edison said from 25 to 40 engineers worked for four months to pare down a list of 190,000 devices at the San Onofre Nuclear Generating Station to 32,000 electronic components and finally to 450 items that had some potential date connection. It will take the company another year to analyze those devices and fix the ones that will fail in the year 2000." (I tried, without success, in 1998 to talk to Mr. Trapp's office so that he could confirm or deny these statements.) Assuming that the facts as stated in the LA Times report are accurate, it is heartening to know that such extraordinary effort went into checking out and remediating systems at the San Onofre Nuclear Generating Station. One hopes that all of the electric power industry and the nuclear power industry were similarly diligent and thorough. Even with the utmost diligence, however, undoubtedly some systems were missed or are not adequately assessed, tested, repaired, or replaced. There are in fact reports of actions that have been taken to address such problems. For instance, one of the earliest reports after the rollover concerned eight US utility plants that experienced clock synchronization problems According to an ABC News report, these particular problems were quickly fixed. It is quite possible as the report pointed out that other plants may have experienced similar problems, but may not have reported them. For this thread, see http://hv.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=002CoA What about the possibility of problems occurring, problems that may be small and quickly addressed or problems of whatever size that may not be readily noticed or addressed? Let us assume that overall the electric power industry and the nuclear power industry acted in extraordinarily diligent ways pre- and post-rollover. Even so, the public record shows known Y2K- related problems have occurred involving these industries both here and abroad. For readily accessible examples, see the older GICC archives listed at http://hv.greenspun.com/bboard/q-and-a.tcl? topic=Grassroots%20Information%20Coordination%20Center%20%28GICC%29.
These problems that have occurred could have resulted from causes involving the following: 1) some systems that should have been remediated were missed; 2) some systems may not have been adequately remediated or replaced; 3) a decision may have been made to "fix on failure", that is to fix or replace a system or set of integrated set of systems if and when it failed (or as and when its failure became evident). There is an ever present possibility that a small problem may not be caught immediately. That small problem can trigger other problems and soon it may become impossible to trace the initial cause of the problem. This may make it impossible to establish a cause-effect relationship that involves one or more Y2K-related problems. In speculating concerning the possible connection between problems that might have been Y2K-related and problems that were not, it is helpful to keep in mind that there may be no simple and direct connection between a Y2K-related problem and, say, the explosion of a manhole cover. A connection, if and when it exists, may be quite indirect. For instance, the utility may have been operating partly or fully on manual, on and off on a short term or long term basis. That may have resulted in irregularities and spiking that could have in turn triggered a spark in an old or faulty cable. Such irregularities and spiking could also have weakened a cable that had previously been functioning well (as had been the case in the Chevy Chase Maryland situation.) If effect, irregularities and spiking and changing the voltage on a line could serve as "the straw that broke the camel's back". In another situation the voltage going through the line may have been changed using automatic controls that had developed some Y2K-triggered anomaly. The amount of voltage may therefore be incorrect. This too could result in irregularities that could result in abnormal changes that could trigger a problem in a cable. "The Engineer" observed recently that "It's probably a phasing issue where the power nodes are out of sync. ("The Engineer's 1/30/2001 observations about ongoing Y2K problems can be seen at http://www.gwu.edu/%7Ey2k/keypeople/gordon/EngObs.html ) Another engineer who has direct knowledge of the Chevy Chase situation informed me that there had been changes in the voltage during the time from that the Chevy Chase incident occurred.
While there is abundant evidence of manhole cover explosions occurring prior to the January 1, 2000 rollover, these incidents tended to differ notably from post-rollover incidents in the following regards: quantity, frequency, dramatic nature of the explosions, timing (in terms of seasonal periods of peak loads) , and geographic spread of such occurrences. The differences seem to have been a factor in the Electric Power Research Institute's decision in the year 2000 to establish a new task group to study the phenomena. (For references regarding pre- and post- rollover incidents, search the archives listed at the bottom of the Grassroots Information Coordination Center homepage at http://hv.greenspun.com/bboard/q-and-a.tcl?topic=Grassroots% 20Information%20Coordination%20Center%20%28GICC%29. Additional internet searches can also be of help. Please feel free to email me if you have trouble finding relevant postings in the archives.)
-- Paula Gordon (firstname.lastname@example.org), July 12, 2001.
I noticed too late that the last part of the next to last paragraph needs some clarification. Also "time from" should be "time frame".
It should read as follows:
"The Engineer" observed recently that the cause of the manhole cover explosions is probably a phasing issue where the power nodes are out of sync. ("The Engineer's 1/30/2001 observations about ongoing Y2K problems can be seen at http://www.gwu.edu/% 7Ey2k/keypeople/gordon/EngObs.html ) Another engineer who has direct knowledge of the Chevy Chase situation informed me that there had been changes in the voltage during the time frame that the Chevy Chase incident occurred.
-- Paula Gordon (email@example.com), July 12, 2001.
Headline: Pepco Digs For Answers After Outages; City Studies Utility's Role in Breakdowns
Source: Washington Post, Friday, July 13, 2001; Page A01
URL: http://www.washingtonpost.com/wp-dyn/articles/A55385- 2001Jul12.html
In the 17 months since the first in a stream of sometimes violent disruptions, the utility delivering electricity to the capital city has gone from confidence that its Georgetown network was fine, if dated, to a growing recognition that there might be hazardous conditions beneath the streets.
A consulting firm told Potomac Electric Power Co. that its cables could overheat in certain situations. Pepco teams embarked on an unusual, systematic inspection of Georgetown's manholes and emerged with details of just how choked with cable they had become. Cable exhumed after a May 15 incident displayed the telltale signs of load stress.
None of the subterranean problems has been pinpointed as the source of even one of the smoking manhole eruptions that have befallen Georgetown, where merchants claim that one outage last month cost them at least $8 million in sales and perishable inventory, and where electricity no longer seems a sure thing.
But Pepco cites them as contributing to its May decision to shun piecemeal patching in favor of a crash, $31 million replacement of the bulk of Georgetown's electrical capillaries, possibly beginning as early as next month.
Explanations of Pepco's woes have noted an aging system in Georgetown. But Pepco was always aware of that and felt that performance did not dictate repairs comparable to those about to take place.
Now, it says, it knows more about below-ground realities as Georgetown, a nexus of Washington's tourism, nightlife and high-end living, awaits a project that will carve up its sidewalks, streets and daily habits for at least two years:
• A consulting firm hired by Pepco found that its practices "may not be adequate" to keep cable from overheating in some configurations. When lines share space underground, their currents must be reduced to avoid excessive heat, which can damage insulation and enable electricity to arc. But Pepco might not have been ratcheting back enough when primary and secondary lines are adjacent, not only in Georgetown but across the city, the consultant said. "We thought we had the appropriate [current] ratings for our cables," said Bill Gausman, Pepco's general manager for asset management. "When they brought this issue to our attention, we agreed with them. We're changing our design criteria."
• Manhole inspections, begun after the first incident in February 2000, underscored howchockablock cables were in ducts under Georgetown. As demand rose over the years, cables were added -- a fact reflected on Pepco's own maps. But primary cables were depicted on one set of maps and secondary on another, Gausman said. The inspections drove home "how intermingled the different operating systems were" in manholes. Such glut not only can cause too much heat, it means an insulation fire in one cable can leap to another, and another.
• Using a new computer model and data provided by Pepco, the consulting firm calculated that load problems could develop at any of 19 Georgetown locations under exceptional demand.
• Cable examined after an incident at 31st and P streets showed signs of deterioration. Cable is usually composed of three elements: a conductor, rubber insulation and an outer jacket. When loads are too great, "you will see the jacket start to separate from the insulation," Gausman said. That raises the possibility of moisture getting in and electricity getting out.
A Closer Look
The D.C. Public Service Commission, which oversees utilities in the city, hired a consulting firm to provide a report by November on Pepco's practices. Simply put, was the utility a victim of bad luck and unavoidable deterioration, or remiss in how it operates? Should it have worked to relieve cable congestion, for example? Known about possible thermal difficulties? Done more inspections earlier?
The consultant's report, the commission's chairman said, could help determine whether Pepco can recoup its Georgetown repair costs from ratepayers and whether new operating standards are needed.
"I don't believe, at least based on what I've seen up until now, I don't believe that Pepco has been acting with malice or that they're trying to hide anything," Chairman Angel M. Cartegena Jr. said.
But the commission, which does not have enough staff to monitor Pepco, decided that an independent examination of Pepco's overall practices was appropriate because "there was no real answer as to why these things were happening."
They are happening still.
Through July 3, Pepco had almost as many "manhole events" in Georgetown this year -- 11 -- as it had in the previous five years combined -- 13. The most severe was just last month, when power went out for three days.
"When November comes, I want to stand there at a press conference and announce to District residents definitively what we believe the problem was," Cartegena said.
Pepco has confidence that its practices, designs and maintenance "are comparable to any in the industry," Gausman said, and that any review will underscore that. Even now, service in Georgetown remains "very, very reliable," he said, although there has been an unprecedented string of misfortunes.
"No one that has been around here has ever remembered either seeing or hearing the number of events that have occurred in one area in so short a period of time," said Gausman, who has worked for Pepco for 27 years.
H. Lee Willis, a vice president of ABB Power T&D, the company that Pepco hired to analyze its systems, said he did not know of "anything that Pepco did wrong." Repeatedly, ABB concluded that Pepco met or exceeded industry norms in specific areas of engineering and policy. For example, ABB said that putting multiple cables in ducts and manholes to accommodate rising demand is common industry practice because space underground is tight and installing additional ducts is expensive and disruptive.
Calling Pepco's managers and engineers "very good people," Willis said "they leave more margin of reliability than most utilities. . . . They practice among the most conservative policies in the industry."
The D.C. Office of the People's Counsel, which represents ratepayers, has aggressively questioned the quality of Pepco's performance. It hired a consulting firm that raised concerns, particularly about aging equipment. The office has made reference, too, to recent union comments about cuts in Pepco's staff and maintenance.
Local 1900 of the International Brotherhood of Electrical Workers, which represents most Pepco employees, says staffing levels have been reduced by nearly 40 percent. But the local says those reductions did not cause recent incidents. There is little maintenance that can be done on cables that are, by and large, out of sight in buried ducts, said Jim Hunter, the local's president and business manager.
"If I could relate this stuff to a lack of maintenance, I'd be the first one to stand on a bandstand to do it," Hunter said. The company could do a better job of cleaning manholes, he said, but overall, "Pepco probably has one of the best-trained underground departments in the country."
How Things Work
Power companies put cable underground, usually in commercial areas, because such networks are less aesthetically offensive and more reliable. Businesses can count on power because wind, snow, ice and the occasional errant vehicle cannot knock down lines, as they can when electricity arrives overhead via poles, as it does in many residential neighborhoods.
Still, underground networks are not perfect. External or internal heat sources can weaken insulation. Weaknesses can occur, too, if cable was badly made or installed; if animals crawl into ducts and dine on cable; or if someone or something nicks a buried line. Pepco said, in fact, that a gas company crew touched off three manhole explosions in Georgetown on Feb. 18, 2000, the first of the recent serious problems. Washington Gas denied it was the cause.
Detecting weaknesses or nicks or failures underground is difficult, however. According to Willis, there is no guaranteed method of testing miles of buried cable. Only manholes provide a window, and a limited one at that.
Manholes are an essential ingredient of underground networks: Cable can be pulled only so far without damage, so every few hundred feet it must be cut and a fresh section begun. Manholes are dug to give work crews access to splice sections. Over time, crews can check splices -- any system's weakest link -- but they still cannot see deep into the ducts that bring cables to and from manholes. Even when a splice is checked for excessive heat or to see if it appears intact, it is still possible that something untoward is happening down the line.
Inevitably, there are manhole events, in which covers shift, smoke or flame in response to the volatile blending ofelectricity and gases below. They can occur in any underground system. In Washington, more occur outside of Georgetown than in it, although most are barely noticeable.
But Ralph Bernstein, formerly of EPRI, an institute that does research for the utility industry, calculates that each year, there is a severe event -- lots of smoke or an explosion -- for every 10,000 manholes. Those in Georgetown tend to be severe because of the peculiarities of the network there, Gausman said.
Because Metro never built a subway line to the neighborhood, there was never an opportunity to revamp the distribution system, which might have increased the number of ducts, making segregating cables easier. So, as demand in Georgetown has risen, additional cables have been pulled through existing ducts. That has put more of them near each other, raising issues of heat and mutual burning.
No Metro overhaul also means that many existing ducts are decades-old terra cotta, which would not be installed today because other materials are better. Cables in them date from the 1970s and 1980s, which is not ancient but not up-to-date, either.
Even so, before the recent spate, Georgetown had fewer outages than Pepco's system average, its figures show. "We did not have a history of failure," Gausman said.
In 1998, Pepco decided that at some unspecified date it would upgrade some of the Georgetown network. From 1990 to 2000, power demand there rose 7.5 percent, compared with 5.1 percent in its system overall, and Pepco wanted to be able to accommodate more growth. But in the short term, there were no known load issues in Georgetown, Gausman said. The Georgetown system was not sleek, but it functioned.
Should Pepco have overhauled Georgetown before it could go bad? Simply because it was older? After all, everything deteriorates eventually. "The older the infrastructure, the shorter its remaining life," said Bernstein, formerly of EPRI.
But within the industry, there appears to be a simple philosophy: Don't fix it if it ain't broke. J. Earl Coffman, manager of engineering for the utility that serves Philadelphia, said he has 100- year-old cable in service and no plans to remove it: "Because it works. Because it hasn't failed."
John Smatlak, director of service performance for Dominion Virginia Power, said he has 70-year cable that is doing fine: "We do not replace cable based on age. We replace cable based on performance."
Some analysts believe that once performance starts to slip, each event imposes more stress on a system, which makes more events likely. Given what was happening in Georgetown and what Pepco learned from inspections and ABB, the utility decided that rather than "piecemeal Georgetown forever," it would undertake an overhaul more extensive than it had planned in 1998, Gausman said. Other utilities will use the opportunity to do work in Georgetown as well.
"We want to show that we are serious," Gausman said, "that we're going to do what it takes to ensure not only that we have a reliable system, but make our customers feel it is safe to walk the streets."
-- Andre Weltman (firstname.lastname@example.org), July 13, 2001.
Thanks, Andre, for posting the July 13, 2001 article from the Washington Post.
-- Paula Gordon (email@example.com), July 13, 2001.
No prob, Paula.
<< Should Pepco have overhauled Georgetown before it could go bad? Simply because it was older? After all, everything deteriorates eventually. "The older the infrastructure, the shorter its remaining life," said Bernstein, formerly of EPRI. But within the industry, there appears to be a simple philosophy: Don't fix it if it ain't broke. J. Earl Coffman, manager of engineering for the utility that serves Philadelphia, said he has 100- year-old cable in service and no plans to remove it: "Because it works. Because it hasn't failed." John Smatlak, director of service performance for Dominion Virginia Power, said he has 70-year cable that is doing fine: "We do not replace cable based on age. We replace cable based on performance." >>
This then begs the question, why are *Georgetown's* cables failing so much and these others aren't? And if it is true that once failures begin they cascade (sure makes sense) then what's in store for the other places -- virtually everywhere in the northeast -- that century- old cables are in use, and not being replaced yet?
-- Andre Weltman (firstname.lastname@example.org), July 13, 2001.