Trenchless Technology

SEP 2018

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W W W.T R E N C H L E S S T EC H N O LO GY.C O M 55 any necessary enabling works that were required prior to mobilization to the project site. In addition, the specialist team held regular dialogues with the City to clearly communicate and understand the scope of the work, set clear objectives, and determine the best tools available to optimize data output . Having a thorough understanding of the pipe and asset con•iguration, along with system constraints and •ield conditions, were crucial for se- lecting the best available technology. The different pipe diameters ranging from 20 in. and smaller, the varieties of pipe materials, as well as the vola- tile operational conditions were all dominant considerations that in•lu- enced the decision-making process in tool selection. It was also a requirement that the inspection tool could be inserted un- der pressure through a •ire hydrant and would provide visual assessment of the condition of the pipe and leak detection data. Leaks, corrosion, evi- dence of tuberculation and any other visible pipe wall defects that would suggest deterioration, were all of par- ticular interest to the City. Forty locations were identi•ied for assessment and involved the utiliza- tion of •ire hydrants as access points. These pipes ranged from 4- to 20-in . in diameter, all varying in materials, age, and operational pressures. Wet barrel •ire hydrants were selected as insertion points, and encompassed a minimum of 50 ft upstream and downstream on deployment . APD utilized a CCTV for visual condition assessment coupled with acoustic leak detection to complete the project and performed the inspec- tions when the pipes were still in ser- vice, causing no disruption to supply. A Look at the Results The City of Santa Monica's collabo - ration with APD yielded results that contradicted the City 's working as- sumptions for renewal and replace- ment . It was concluded that age is not a reliable indicator of pipeline condi- tion and is not a solid foundation on which to base capital disbursement . In one instance, a 102-year-old pipe, which the department had prioritized for replacement , had no obvious signs of degradation and appeared structur- ally sound, and therefore required no replacement at this stage. In contrast , the inspection also found a 30-year-old pipe that was not factored into the capital improvement plan but was presenting conditions that would warrant replacement . With regard to overall condition of the main lines, it was discovered that the hydrant laterals were in worse condition and in some cases, the tu- berculation was so excessive that the inspection had to be abandoned as access was signi•icantly restricted or impossible. In these cases, alternative locations were designated. The inspection program also re- vealed that the unlined cast iron pipe closest to the Paci•ic Ocean was in poor condition in comparison to sec- tions of pipe that were located further inland. Lined pipe in the same area was minimally affected except for evi- dence of tuberculation and corrosion activity on joints that were not lined. Discrepancies and defects in map - ping were also identi•ied and anno - tated with the facilitation of GIS and spatial updates to the City 's GIS sys- tem. Such inconsistencies included misalignment of pipes and inaccurate pipe location, identi•ication and loca- tion of lost or unknown valves, actual and recorded valve conditions and op - erabilities, pipe material changes and previous repairs, to name but a few. In utilizing the data from the in- spection program, the City is in a better position to minimize unneces- sary expenditure on remediation and repair of low-priority pipes and focus investment of resources and time on high risk areas. In a climate where the funding for water infrastructure replacement and renewal is not abun- dant , condition assessment technolo - gies and data have proved to be the compass for an effective asset man- agement strategy for owners and op - erators of water distribution systems alike. Through the implementation of this program, the City of Santa Monica can feel more con•ident in establishing a sound remediation plan with a better return on investment for the future. Emma Quall is vice president of Aquam Pipe Diagnostics The Santa Monica Department of Public Works worked with Aquam Pipe Diagnostics to execute video inspection and condition assessment services in an effort to investigate the current state of its potable water pipelines.

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