Wastewater Forcemain Condition Assessment Program
In April 2012, the District signed a Federal Consent Decree requiring improvements to the collections system aimed to eliminate illegal discharges of untreated raw sewage. As part of the requirements outlined within Consent Decree, a force main non-destructive testing and condition assessment program must be developed and implemented. The force main condition assessment program incorporates an asset management approach and risk categorization scale that classifies each of its force mains as high, medium, or low risk based on a previously conducted prioritization. The District and Jason Consultants (a wholly owned subsidiary of Pure Technologies) have developed individualized assessment strategy for each high and medium risk force main including the implementation of various inspection techniques and technologies.
Condition assessment and management of wastewater force mains has historically proven difficult for pipeline owners and operators. Conventional gravity sewer inspection methods (e.g. visual inspection, sonar and laser profiling) do not provide a full condition assessment of most pressure pipes since the loss of structural capacity cannot be quantified with these methods. As part of the condition assessment of force mains, leak and gas pocket detection is crucial since their presence is often a preliminary indicator of a potential failure location. Gas pockets in force mains are of significant concern as they are the primary failure mode for these critical pipelines. Hydrogen sulfide gas within the wastewater may be converted to sulfuric acid by bacteria in the slime layer on the pipe wall, which may cause corrosion and eventual breakdown of the pipe’s exposed surface.
Based on Pure Technologies’ assessment of over 8,000 miles of pressure pipe, including over 400 miles of wastewater force mains, our clients have found that pressure pipes typically do not deteriorate or fail systematically along their full length. Rather, pipe condition is usually related to localized problems due to design, manufacturing, installation, environmental, operational, or maintenance factors. By identifying the localized areas of deterioration and performing “surgical” repair techniques, utilities can manage their pressure pipelines for often less than 10% of the replacement cost.
After completion of the SmartBall inspection and other screening techniques such as pressure transient monitoring and external corrosion evaluations, the District and Jason Consultants have identified locations for external evaluation for several force mains to determine the condition of the pipe wall. These evaluations will be conducted using various techniques including visual, physical measurements, and ultrasonic testing with the goal of District staff providing most of these inspection services. Jason Consultants will then work with District staff to deliver force main specific management strategies including:
- Repair, rehabilitation, or replacement recommendations;
- Recommendations for modifications to the force main including future inspection needs and air release valves;
- Re-evaluation of force main risk based on inspection results and condition assessment;
- Remaining useful life estimations;
- Emergency response planning for high and medium risk force mains.
Pure Technologies has the complete portfolio for sewer force main and large diameter gravity main inspection. As the trusted global leader, we have successfully inspected thousands of miles of pipeline.
Pure Technologies is helping utilities manage their buried infrastructure through its Assess & Address which can often be implemnented for only a fraction of the capital replacement cost
Baltimore County Department of Public Works (DPW)has been working with Pure Technologies to manage its force main inventory since 2011. Through proactive and regular assessment, DPW has been able to identify select areas of pipeline deterioration, thereby avoiding unnecessary pipe replacement.