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City engineering says microtunneling run completed on East Bayshore pipeline
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Summary
Public Works engineering staff reported successful completion of a microtunneling installation on East Bayshore to avoid deep open‑cut excavation amid groundwater and utility conflicts; staff described daily settlement monitoring, special pipe materials and that the method shortened construction time from months to weeks.
Engineering staff told the committee that contractors recommended a microtunneling approach for a complex segment on East Bayshore and Corporation Way where groundwater and multiple utilities made open‑cut excavation risky and slow.
Rajeev (engineering staff) said the microtunneling run replaced an earlier plan for open cut, which would have taken an estimated six to seven months; the microtunneling installation took roughly three to four weeks and crews completed the run the week of the presentation. Staff described daily settlement monitoring using surface survey points and inclinometers, with a settlement limit of 1 inch; monitoring showed movements well below the threshold.
The presentation included technical details: contractors used fiber‑reinforced pipes (not the city’s typical HDPE or standard SD pipes) with higher load capacity for this method, specialized hydraulic cooling systems for the tunneling machine, slurry separation and recycling systems, and grouting around adjacent sewer pipes to stabilize voids. Staff said they monitored nearby sewer and utility lines carefully during operations and performed grouting where necessary to prevent settlements or loss of support.
Committee members recognized the complexity and engineering controls used to protect adjacent infrastructure and congratulated the team for completing the run on schedule.
