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INTRODUCTION TO TRENCHLESS TECHNOLOGY. Traditional Methods. First suited for “gre enfield” Low tech – little change over past 50 yrs. Level of planning & implementation basic “ Non-greenfield” – surface disruptions, underground utilities. Trenchless Technologies.
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Traditional Methods • First suited for “gre enfield” • Low tech – little change over past 50 yrs. • Level of planning & implementation basic • “Non-greenfield” – surface disruptions, underground utilities
Trenchless Technologies • Thrust Boring & Pipe Jacking (pre-1900’s) • Auger Boring (1940) • Impact Moling (1962) • Directional Drilling (1971) • Impact Ramming (1980) • Pipe Bursting (1980’s)
Definition ofTrenchless Technologies “A family of methods, materials, and equipment capable of being used for the installation of new or replacement or rehabilitation of existing underground infrastructure with minimal disruption to surface traffic, business, and other activities.”
New Construction Techniques H.D.D. Pipe Bursting Micro tunneling Pipe Jacking Auger Boring
Horizontal Directional Drilling • Lengths of 15 - 1800 m • Diameters of 25 - 1200 mm • Applications: • utility conduits • Pipelines • gravity sewers • force mains • horizontal remediation wells • geotechnical investigations
Pipe Bursting • Lengths of 100 - 900 m • Diameters of 75 - 1060 mm • Applications: • replacement of force mains • replacement of gravity sewers Static Head Pneumatic Head Hydraulic Head
Microtunneling • Lengths of 25 - 225 m • Diameters of 250 - 3050 mm • Applications: • gravity sewer installations
Pipe Jacking • Lengths of up to 490 m have been achieved • Diameters of 1060 - 3050 mm • Applications: • large diameter gravity sewers and force mains
Auger Boring • Lengths of 12 - 150 m • Diameters of 200 - 1500 mm • Applications: • relatively short crossings of pipes and conduits
TWO CASE HISTORIES (一)Pipe Bursting (二)Horizontal Directional Drilling
Alternatives • Parallel the existing gravity trunk sewer with a new gravity trunk sewer • Construct a series of 5 new pumping stations and pump to adjacent sewerage area
Parallel Trunk Sewer • Advantages • Maintains gravity flow • Disadvantages • Construction in silty sand to clayey material 3 to 6 metres deep with high groundwater in close proximity to Millstone River, a highly sensitive Coho salmon habitat stream. • Additional right-of-way would be required • Cost Estimated at $5.1 million
Pumped Option • Advantages • Minimizes environmental impacts as pump stations and forcemains for the most part would be constructed in existing right-of-ways. • Disadvantages • Added undesirable long term operational costs to the City of Nanaimo • Cost Estimated at $5.2 million
Pipe Bursting Researched as a Possible Alternative • Advantages • Less environmental impact as excavation is minimized • Gravity flow maintained • No additional right-of-ways required • No long term operational and maintenance costs associated with pump stations • More cost effective than alternatives • Disadvantages • Upsize required at the upper limit of PB technology in North America; however, there had been limited success • Lengths 100m to 175m • Limited availability of contractors in North America with capability to perform upsize of this nature
Demonstration Section • Ability to burst project lengths (100m to 175m) • Ability to burst pipe couplings • Ability to burst concrete encasement • Although some difficulties encountered, remaining project was subsequently awarded
650mm (26”) 750mm (30”) 350mm (14”)