Trenchless Technology

DEC 2018

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28 T R E N C H L E S S T EC H N O LO GY D EC E M B E R 2018 der a design-build contract for the Capital Regional District . As part of the project , a new pipeline had to be installed underneath the harbor to convey wastewater to the new plant . Due to the length of more than 3,000 ft through very hard granitic rock, the joint venture decided the crossing was to be constructed by Horizontal Directional Drilling . The high anticipated stresses during pull back, required a 1-in. wall 42-in. di- ameter steel pipe to be specified. The pipe laydown area went through a quiet residential neighborhood in the City of Victoria, where commu- nity activities were organized includ- ing paintings by local schools on the pipeline. Corrosion protection was neces- sary since the pipe was to convey raw sewage. Exterior pipe coatings were also necessary where the pipe passed through potentially corrosive over- burden soils. Drilling was completed in April 2018, three months ahead of schedule. The project was completed in June 2018 with the successful test- ing of hydrostatic pressure for leak- age. The WWTP construction is cur- rently under way and is scheduled to be completed in 2020. Black & Veatch Corp. City of Minneapolis Water Main Replacement Faced with an aging 54-in. water main that is more than 70 years old, the City of Minneapolis contracted with Black & Veatch to perform a study, detailed design, and construc- tion management services to replace the water main. The initial study concluded that replacing the exist- ing water main with a new pipeline tunneled beneath the Mississippi River would be the best long- term alternative to balance both cost and water main maintenance. The design included 920 lf of 48 in. water main under the Mississippi River using microtunneling . Shorter sections of open-cut construction methods are required to connect the new 48 in. water main to existing piping . The working shaft will be approximately 20 ft in diameter, and the retrieval shaft will be 10 ft in diameter. Both shafts will be constructed using wa- ter tight ground support systems to mitigate high groundwater inflows and prevent migration of a contami- nated groundwater plume. The re- trieval shaft will be 130 ft deep to ac- commodate the existing topography. The project will also include the re- placement of 48-in. piping installed vertically in an existing , 80-ft deep shaft constructed in 1917. The annu- lar space in this shaft will be grouted once the new pipe is installed. Hatch Corp. Regional Municipality of Halton's Mid-Halton Effluent Outfall Construction of the Regional Mu- nicipality of Halton's $80 million Mid-Halton Effluent Outfall was completed earlier in 2018. Hatch managed this project from the Envi- ronmental Assessment stage through preliminary design , detailed design and construction . The project was completed entirely by tunneling and included two 50-m deep shafts, 4.2 km of onshore tunneling beneath residential and commercial neigh- borhoods and 2.1 km of offshore tunneling beneath Lake Ontario. The tunnel was mined to 3.5m in di- ameter and lined to 2.6 m in diam- eter. Offshore, the tunnel intersected with 18 pre - drilled riser/diffuser as- semblies. Onshore, the shaft at the wastewater treatment plant was fin- ished as a baffle - drop structure and included a micro - turbine unit to generate electricity from the falling effluent . CDM Smith Providence Water Emergency Repair, Risk Assessment & Inspection Providence Water (PW), Rhode Island's largest water utility, has been relying on the expertise of CDM Smith professionals for its Prestressed Concrete Cylinder Pipe (PCCP) assessment and rehabilita- tion needs for more than 20 years. Following a catastrophic failure of its 102-in. prestressed concrete cylinder pipe (PCCP) aqueduct in 1996 that caused significant property damage and interrupted water supply to their wholesale customers, PW retained CDM Smith to perform emergency repair services and develop a com- prehensive investigation program for PW, including a pipeline risk assess- ment and inspection program, which has facilitated systematic repairs to the 78-in. and 102-in. Supplemental Tunnel and Aqueduct (STA). CDM Smith has assisted PW with the im- plementation of the program. Most recently in 2017, CDM Smith completed rehabilitation of approxi- mately 1,285 lf of 78-in. PCCP via sliplining to restore the structural in- tegrity of the aqueduct . Data collected from visual , structural sounding , and electromagnetic (EM) inspections, compared with previously developed failure risk curves and repair prioriti- zation of distressed pipes, identified highly distressed 78-in. PCCP pipe in need of immediate repair. These pipe reaches were repaired with 69- in. diameter centrifugally cast , fi- berglass reinforced, polymer mortar (CCFRPM) using a combination of sliplining and open-cut construction methods. Cardno Subsur face Utility Engineering – Phoenix South Central LRT Project Cardno was selected as a Util - ity Engineer on the Valley Metro program management team for the South Central LRT project in Phoe- nix , Arizona, providing subsurface utility engineering services utilizing the ASCE 38-02 standards as well as survey/mapping services, as part of the team with HDR . The Cardno field investigations team mapped more than 700,000 lf of subsurface utili- ties through two phases, effectively mapping 80 percent more utilities than were on utility record alone. The investigation discovered more than 125 unknown utilities stretch- ing more than two miles of undocu- mented lines. These findings greatly reduced the risk of impacts on this project . The project included con- ducting records research (CI /ASCE 38-02 Quality Level D), field observa- tions (Quality Level C), designating

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