City of LA - Sewer Inspection Report

Client: City of Los Angeles- LA Sanitation Wastewater Engineering Services
Project: Sewer Inspection Report




Project Overview

Pure Technologies U.S. Inc. (Pure Technologies), in collaboration with Black & Veatch, performed a SmartBall® inspection of the Bohlig Road – Highbury Pumping Plant (PP) 604 Force-main, 8th Street – Dacotah PP 606 Force-main and the 85th Street – Manchester PP 601 Force-Main. The purpose of the Pilot SmartBall inspection was to identify and locate leaks and pockets of trapped gas along the pipeline. Acoustic and sensor data was collected and recorded as the SmartBall tool traversed the pipeline. This data was evaluated to identify acoustic events associated with leaks and pockets of trapped gas. Overall, the sections inspected showed no fully developed gas pockets (trapped gas) or detected leaks. Some migratory/ entrained air events and gas slugs were observed. The existence of such air/gas events are of less risk to the pipeline than a fully developed gas pocket. A migratory entrained air event is characterized by small, moving bubbles of gas within the pipeline. Entrained air is not typically static in a pipeline and frequently migrates with the flow. These moving pockets of gas are generated in three ways:

  •  They can be introduced at the pumping station as a result of air becoming entrained in the sewage as it plunges into the wet well or by inefficiencies within the pump station.
  • They can be created at the tail of a hydraulic jump at the end of a fully developed gas pocket where small pockets of gas diffuse into the liquid phase and are carried downstream with the flow.
  • Finally, entrained air may be created by the biochemical processes inherent to sewage mains.




EWC worked with B&V and provided a QA/QC effort of all technical memorandums, presentations, and reports and provide recommendations to B&V and Pure Technology. The review involved technical discussions for clarity and observations for effectiveness and viability in the field. EWC provided findings and input and suggestions for future opportunities.


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