Case Studies

Transmission Line Condition Assessment and Rehabilitation Program

Rafael’s extensive experience in providing condition assessment and rehabilitation of large diameter pipelines includes critical pipelines in California to Florida. This expertise affords GCWA the ability to better manage the specialty testing firms, and help determine the most reliable and cost effective rehabilitation approach.

Additionally, he has supported the governmental agencies in using this knowledge to develop capital improvement budgets and schedules.

Rafael’s recent condition assessment efforts include PCCP, steel, DIP and CIP pipelines. Some of these lines have included the installation or modifications to long term dynamic monitoring systems. The assessed lines have included raw and treated water lines, and force mains. Below is a list of pipelines in which he has led the assessment.

Condition Assessment of Water Main City of Houston, TX

The City of Houston experienced a catastrophic failure of a 60-inch PCCP line constructed in the mid 1970’s. While the repair was underway for the failed section, a team of engineers lead by Rafael Ortega performed a condition assessment of approximately 23,000 LF of the line, referred to as Segment 1. Several additional sections were found to be in distress and subsequently rehabilitated. The remaining portion of the line was not assessed due to water demands and limited system interconnects.

In 2010, the City of Houston authorized a team of engineers to assess Segment 2 of the line that was approximately 15,500 LF long. In order to isolate that segment of the line, several butterfly valves and interconnections had to be incorporated into the project. Additionally, the planning effort included development of a valve closure and a sequencing map to aid the City in minimizing the impacts to its water system pressures. The challenges for the design included determining the best way to mitigate impacts to the Gus Wortham Golf Course and the adjacent Forest Park Cemetery—which the 60-inch pipe crossed within water line easements.

The team of engineers lead by Rafael Ortega performed a manned entry of the line, supported by the Electro Magnetic Testing (EMT) performed by others, identified the appropriate material testing of the pipe sections, and evaluated the risks of failure. Based on the manned entry and EMT findings, the pipeline was found to have 20 sections, or less than 3% of the line, with distress. Based on the material testing, the risk assessment concluded that only 7 sections of the line were in need of rehabilitation. The majority of the 7 sections existed in the portion of the line parallel to a UPRR track on one side and a residential neighborhood on the other side. Due to the critical nature of the line and the potential consequences of failure, a dynamic monitoring system (Acoustic Fiber Optic – AFO) was installed in the portion of the line assessed.

The 7 sections were rehabilitated using point replacements, repair clamps and a carbon fiber reinforcement polymers (CFRP) system. Additionally, the pipe joints, which were originally manufactured with “shorting straps”, were bonded” for continuity of the line. Finally, cathodic protection test stations were installed to aid in monitoring of the line and facilitate the possibility of a future cathodic protection system. To date, no further failures in the line have occurred in either Segment 1 or 2.

Condition Assessment Condition Water and Sewer Department; Miami, FL

In September 2014, the Miami-Dade Water and Sewer Department (WASD) issued an emergency construction contract to rehabilitate several sections of 48-inch PCCP line constructed in the early 1980s which were showing distress activity based on the previously installed acoustical fiber optic (AFO) monitoring system.

In 2011 and 2013, two separate construction contracts had been issued by WASD to perform similar rehabilitation.

The original assessment in 2011 was performed using remote field transformer coupling (RFTC) evaluation via the PipeDiver technology. This assessment was prompted due to a prior failure of the PCCP line several years earlier. Due to the limited records available, the analysis was based on a number of assumed values.

Therefore, at the request of WASD, a team of engineers lead by Rafael Ortega was authorized to perform a manned entry of the 48-inch within the limits of the line where the CFRP was to be installed, or approximately 2,800 LF to confirm the prior RFTC findings and evaluate the performance status of the previously performed CFRP installation. During the assessment, several deficiencies within the pipeline were encountered. These deficiencies included; joint grout failure with level 3 corrosion, longitudinal cracks with calcification build up, and various deficiencies in 17 of the prior 24 CFRP rehabilitated pipe sections. As a result of these deficiencies, WASD requested support in determining appropriate repair protocol of the deficiencies.