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Published byDarcy Barnaby Parrish Modified over 9 years ago
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David Kerr, PE Lessons Learned from recent challenging HDD installation
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GHD @ NC AWWA – WEA 2015 Setting the stage The plot: Background - behind schedule before we started Design - this is easy! Bidding - storm brewing Construction - challenges, changes, and what went wrong (and right!) Conclusion - it’s all good - lessons learned
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GHD @ NC AWWA – WEA 2015 Background: need for the project Major industrial client New $4 billion facility (4-5 year construction) Several off-site staging areas Area A - administration and laydown Needed water and sewer services Negotiated with the county to provide water and sewer services Can you do it faster! Industry County
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GHD @ NC AWWA – WEA 2015 Background: need for the project Design 3,100 lf 8-inch water main 8-inch sewer casing 4-inch force main 8-inch re-use main (future) Connect to the existing sewer force main Connect to the new county installed water main Can you do it faster?
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GHD @ NC AWWA – WEA 2015 Design – this is easy! No Easements Good Understanding of Local Geology Power Company Borings WWTP Design Borings Some From Industry Power Plant Report Pipe Material Selection Fusible PVC Permits North End: Industry Permits South End: Less than 5,000 Sq. Disturbance
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GHD @ NC AWWA – WEA 2015 Design – this is easy!
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GHD @ NC AWWA – WEA 2015 Bidding – storm brewing Bidding Questioned the use of fusible PVC – stood by design No new soil borings – added to contract Material classification – no change No rock boring bid item – added a contingent item
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GHD @ NC AWWA – WEA 2015 Construction – challenges Schedule Industry Permit delays Can we do it faster? Notice to proceed Conditional - october 2014 Began searching for alternative access
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GHD @ NC AWWA – WEA 2015 Construction – challenges Alternative access Power easement Across two (2) properties Industry Bank owned property Not all drivable without temporary improvements Environmentally sensitive areas
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GHD @ NC AWWA – WEA 2015 Construction - changes OK go! Industry gave access Active construction site Non-improved roads Changing conditions
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GHD @ NC AWWA – WEA 2015 Construction – changes Stormwater Pond
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GHD @ NC AWWA – WEA 2015 Construction – what went wrong
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GHD @ NC AWWA – WEA 2015 Construction – what went wrong
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GHD @ NC AWWA – WEA 2015 Construction - what went wrong
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GHD @ NC AWWA – WEA 2015 Construction – what went wrong Soil conditions Coastal plain deposits Silty sand Gravel Compacted sand Rock fragments Means and methods right? Drill head selection/plan
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GHD @ NC AWWA – WEA 2015 Construction – what went right All pipes passed testing Third pipe installed with no issues Sewer pumping station operational Water main operational All before industry staff moved in
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GHD @ NC AWWA – WEA 2015 Conclusions – lessons learned Define soil conditions clearly Take the time for soil borings even if you have decent information When working with other contractor’s schedules, have a contingency plan A full time coordinator may be needed Make sure contractor is following frac out plan Fusible PVC cannot be handled like HDPE Bend angles cannot exceed tolerances Ballast water MUST stay no higher than ground elevation Develop a detailed pipe handling plan prior to work
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GHD @ NC AWWA – WEA 2015 Thank You! Questions? david.kerr@ghd.com
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GHD @ NC AWWA – WEA 2015 www.ghd.com
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