Trenchless Technology

Fall Canada 2018

Trenchless Technology is the premier communications vehicle for the trenchless industry. Through our multiple platforms, readers receive insights into the trenchless industry, as well as keep connected to the latest news, products and projects.

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Page 17 of 39

18 T R E N C H L E S S T EC H N O LO GY C A N A DA FA L L 2018 B R I T I S H C O LU M B I A'S C A P I TA L R EG I O N A L D I S T R I C T, a regional municipality that includes Victoria, the province's capital , is in the midst of a $765 million, multi- year, Wastewater Treatment Proj- ect to provide tertiary treatment for wastewater prior to its discharge in the Strait of Juan de Fuca. The CRD, as the district is referred, is the last major coastal community in North America that discharges untreated sewage into the marine en- vironment . Benefitting the core area municipalities of Victoria, Esquimalt , Saanich, Oak Bay, View Royal , Lang- ford and Colwood and the Esquimalt and Songhees Nations, the project is being built to comply with federal and provincial wastewater regula- tions by Dec. 31, 2020. A key component of the overall project is the construction of the McLoughlin Point Wastewater Treat- ment Plant , in Esquimalt . The plant is being constructed by Harbour Re- source Partners a consortium of firms including – AECOM Canada, Graham Infrastructure, HRD/CEI, SUEZ, Gra- ham Capital and Michels Canada. When complete the plant will con- nect to the Clover Point and Macau- lay Point pump stations and treat up to 108 megalitres a day. In order to connect to Clover Point , an undersea pipeline across Victoria Harbour was required between Og- den and McLoughlin points. Due to the location and volume of marine traffic — including a busy cruise ship and ferry terminal — trenchless tech- nology was the preferred method. It was decided horizontal directional drilling (HDD) would be the only vi- able option. Michels Canada was subcontracted using a design-build approach to ex- ecute the 940-m HDD under Victo - ria Harbour. The restricted available workspace required the HDD to have a complex curve geometry to enable precise entry and exit point require- ments by the owner coupled with extremely limited pipe management space in downtown Victoria. The final HDD design included an entry angle of 18.5 degrees and an exit of 12 degrees with 178 m of tangent and 762 m of horizontal and vertical curve of 1,000 m radius. The project included not only the HDD portion but the pipe makeup and management of the 42-in. by 1-in. steel pipe single pull section. The formation identified through- out the crossing was extremely chal - lenging . The extensive geotechnical program required boreholes and rock testing as well as probing that con- firmed extreme undulations that pro - vided various depth of cover along the final HDD profile. The geotechni- cal investigation showed highly frac- tured and low RQD granodiorite with the inclusions of faults. Extensive bathymetric surveys were required for design and to provide Michels with a model which could be trusted. The final HDD alignment included surface casing on the Ogden Point (pipe side) with the 60-in. surface casing installed starting at 1.8 m be- low the existing grade and less than 1 m above sea level . This required the HDD rig to be dug into an engi- neered trench due to site limitations with the back of the HDD rig only meters from the primary cruise ship access for Victoria. The final align- ment was just under 80 m below sea level , including approximately 15 m of ocean, 15 m of sediment and 50 m of bedrock. The drilling was com- pleted through hard rock formation, requiring mud motors and hard rock tooling and ended at elevation 4.7 m above sea level on McLoughlin Point . I M P R O V I N G T H E M A R I N E E N V I R O N M E N T HDD Under the Victoria Harbour By Trenchless Technology Canada Staff

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