Last week a 16-inch water main under Rockville Pike broke, flooding sections of Rockville Pike. To find the leak and repair the damage Washington Suburban Sanitary Commission (WSSC) had to close the water valve to the main cutting off water to 250 households, and excavate a section of pipe partially closing Rockville Pike overnight and into the morning rush hour. WSSC reports that the cast iron pipe was 74 years old and the damage and disruption were limited due to the size of the pipe and WSSC’s practiced response to pipe failure. For a while now WSSC had been repairing and replacing water pipes after they broke or had exceeded their expected lifetime. This strategy was simply planning for failure.
This pipe break last week and the growing number of breaks in the past couple of years sever to highlight the issue of aging infrastructure in the WSSC’s system and America. Though recently, WSSC has been replacing about 55 miles of water mains per year that has not been enough to keep the water delivery system- the pipes fittings and valves within the expected age of the piping. That rate of pipe replacement would replace the water system in 101 years. The pipes in the WSSC system have not been lasting that long. WSSC reports that approximately 37% of the water system delivery pipes are over 50 years old. Though age is not the only factor that causes pipe failure, most of the system’s pipes were designed for an average lifespan of 70 years.
The water pipes installed during the late 19th century were typically described as having an average useful lifespan of about 120 years because of the pipe wall thickness used, but most of WSSC was installed after World War II in the booms of the 20th and 21st centuries. In the 1950s and 1960s of ductile iron pipe that is stronger than cast iron and more resistant to corrosion was introduced and used with thinner walls. Polyvinyl chloride (PVC) pipes were introduced in the 1970s and high-density polyethylene in the 1990s. Both of these are very resistant to corrosion but they do not have the strength of ductile iron. Post-World War II pipes tend to have an average life in the real world of 50-105 years depending on many factors (AWWA). To extend the life of the ductile pipes they were mortar-lined. These linings are meant to prevent corrosion and increase pipe longevity. In the 1970’ steel reinforced concrete pipe with a promised life of 100 years began to be used for the giant water mains by WSSC.
Unfortunately, these concrete trunk lines began to fail catastrophically decades before their promised 100-year life expectancy. Unfortunately, WSSC has 350 miles of steel reinforced concrete pipe. In addition, WSSC ‘s supplier, Interpace, may have produced inferior pipe- the company was successfully sued by WSSC and others and is now out of business. Nine of the WSSC’s concrete mains have blown apart since 1996. After a particularly spectacular blowout 2008 and to prevent future catastrophe, WSSC installed a sensor system along all the concrete mains that cost more than $21 million to alert WSSC of an impending failure, but unfortunately the replacement program became very much an emergency replacement program responding to sensors and smaller breaks.
Ideally, pipe replacement occurs at the end of a pipe’s “useful life”; that is, the point in time when replacement or rehabilitation becomes less expensive in going forward than the costs of numerous unscheduled breaks and associated emergency repairs; rather than waiting for a pipe to fail. Age alone, however, cannot always be used as an indicator of failure, but it is a good predictor in warm weather breaks. In cold weather more pipes fail. There is a relationship between water temperature and pipe breaks. A sudden temperature drop provides a kind of shock to the pipes especially when the pipes are older. Water temperature below 40 degrees Fahrenheit can also cause pipes to become more brittle, and break. That leads to increased pipe breaks in the winter, and why water utilities typically report their February number of breaks- when most breaks take place. For the last several years WSSC pipe replacement program has had more unscheduled emergency repairs in winter.
WSSC has responded to the deterioration of their system by developing a long term plan of what was needed repair and restore their systems. Over the next 10 years WSSC projects they will have to replace over 2,000 miles of water pipe and similar amount or sewer pipes. WSSC estimates that they will have to spend over $2.6 billion dollars in the next five years on capital improvement projects alone and has been studying how to pay for those needs. In 2010, WSSC re-established the Bi-County Infrastructure Funding Working Group to identify near-term options to fund both operations and the $2.6 billion in capital needed to rehabilitate, upgrade and replace water and wastewater infrastructure and related facilities in the next five years alone. The plan they developed was to combine increasing customer charges, refinancing bonds to extend maturities and lower rates and issuing new debt to raise the capital to pay for the rehabilitation of the system.
On October 14, 2015 WSSC sold $390 million of Consolidated Public Improvement Bonds with a true interest rate of 3.426919%. The bonds were rated tripple A -(AAA/Aaa/AAA) by the bond rating agencies: Fitch Ratings, Moody’s Investors Service and Standard & Poor’s, which also reaffirmed WSSC’s AAA rating on its other outstanding bonds. The $390 million 30-year bonds will be used to finance WSSC capital projects and pay down a portion of the Commission’s bond anticipation note program. WSSC is moving forward. This is the third bond sale within 12 months.
This pipe break last week and the growing number of breaks in the past couple of years sever to highlight the issue of aging infrastructure in the WSSC’s system and America. Though recently, WSSC has been replacing about 55 miles of water mains per year that has not been enough to keep the water delivery system- the pipes fittings and valves within the expected age of the piping. That rate of pipe replacement would replace the water system in 101 years. The pipes in the WSSC system have not been lasting that long. WSSC reports that approximately 37% of the water system delivery pipes are over 50 years old. Though age is not the only factor that causes pipe failure, most of the system’s pipes were designed for an average lifespan of 70 years.
The water pipes installed during the late 19th century were typically described as having an average useful lifespan of about 120 years because of the pipe wall thickness used, but most of WSSC was installed after World War II in the booms of the 20th and 21st centuries. In the 1950s and 1960s of ductile iron pipe that is stronger than cast iron and more resistant to corrosion was introduced and used with thinner walls. Polyvinyl chloride (PVC) pipes were introduced in the 1970s and high-density polyethylene in the 1990s. Both of these are very resistant to corrosion but they do not have the strength of ductile iron. Post-World War II pipes tend to have an average life in the real world of 50-105 years depending on many factors (AWWA). To extend the life of the ductile pipes they were mortar-lined. These linings are meant to prevent corrosion and increase pipe longevity. In the 1970’ steel reinforced concrete pipe with a promised life of 100 years began to be used for the giant water mains by WSSC.
Unfortunately, these concrete trunk lines began to fail catastrophically decades before their promised 100-year life expectancy. Unfortunately, WSSC has 350 miles of steel reinforced concrete pipe. In addition, WSSC ‘s supplier, Interpace, may have produced inferior pipe- the company was successfully sued by WSSC and others and is now out of business. Nine of the WSSC’s concrete mains have blown apart since 1996. After a particularly spectacular blowout 2008 and to prevent future catastrophe, WSSC installed a sensor system along all the concrete mains that cost more than $21 million to alert WSSC of an impending failure, but unfortunately the replacement program became very much an emergency replacement program responding to sensors and smaller breaks.
Ideally, pipe replacement occurs at the end of a pipe’s “useful life”; that is, the point in time when replacement or rehabilitation becomes less expensive in going forward than the costs of numerous unscheduled breaks and associated emergency repairs; rather than waiting for a pipe to fail. Age alone, however, cannot always be used as an indicator of failure, but it is a good predictor in warm weather breaks. In cold weather more pipes fail. There is a relationship between water temperature and pipe breaks. A sudden temperature drop provides a kind of shock to the pipes especially when the pipes are older. Water temperature below 40 degrees Fahrenheit can also cause pipes to become more brittle, and break. That leads to increased pipe breaks in the winter, and why water utilities typically report their February number of breaks- when most breaks take place. For the last several years WSSC pipe replacement program has had more unscheduled emergency repairs in winter.
WSSC has responded to the deterioration of their system by developing a long term plan of what was needed repair and restore their systems. Over the next 10 years WSSC projects they will have to replace over 2,000 miles of water pipe and similar amount or sewer pipes. WSSC estimates that they will have to spend over $2.6 billion dollars in the next five years on capital improvement projects alone and has been studying how to pay for those needs. In 2010, WSSC re-established the Bi-County Infrastructure Funding Working Group to identify near-term options to fund both operations and the $2.6 billion in capital needed to rehabilitate, upgrade and replace water and wastewater infrastructure and related facilities in the next five years alone. The plan they developed was to combine increasing customer charges, refinancing bonds to extend maturities and lower rates and issuing new debt to raise the capital to pay for the rehabilitation of the system.
On October 14, 2015 WSSC sold $390 million of Consolidated Public Improvement Bonds with a true interest rate of 3.426919%. The bonds were rated tripple A -(AAA/Aaa/AAA) by the bond rating agencies: Fitch Ratings, Moody’s Investors Service and Standard & Poor’s, which also reaffirmed WSSC’s AAA rating on its other outstanding bonds. The $390 million 30-year bonds will be used to finance WSSC capital projects and pay down a portion of the Commission’s bond anticipation note program. WSSC is moving forward. This is the third bond sale within 12 months.
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