Trenchless Technology

DEC 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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26 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 Jacobs Water Rehabilitation for Emergency and Potable Supply in West Potomac Park The existing water conveyance system located within the National Mall in Washington, D.C ., serves the Washington Monument , Lincoln Memorial , WWII Memorial and the Vietnam War Memorial . The proj- ect included the replacement of 12,000 lf of water mains and 3,000 ft of services installed between 1908 and 1942 by the War Department . Horizontal directional drilling was the preferred trenchless installation method to install new HDPE pipe. The project required minimization of the construction footprint given the year-round high pedestrian activity in the area . Subsurface conditions encountered were fill (fat clays and silts) to sands and gravels overlying low shear strength alluvial deposits. The horizontal alignment followed the existing system however the ver- tical alignment was between 8 to 12 ft below the ground surface avoid ex- isting utilities and to remain above the weak alluvial deposits. Unexpect- ed challenges encountered included historic buried foundations for WWII barracks, working in close proximity to the curious public and creatively managing shallow cover to reduce the potential for inadvertent returns (hydro fracture). Mott MacDonald Bergen Basin Sewer Reconstr uction in Queens The wastewater collection system for the neighborhood of South Ozone Park in Queens passes beneath the heavily traveled Belt Parkway before reaching the Jamaica Water Pollution Control Plant at the western end of JFK International Airport . When the sewer reaches capacity, combined sewer overflows cause untreated wastewater to reach the narrow inlet of Bergen Basin. From there, it flows into Jamaica Bay, the site of impor- tant habitat and a wildlife refuge. Mott MacDonald provided trench- less and tunneling expertise for the construction of a new interceptor sewer under the Belt Parkway. The alignment passed through artificial fill and glacial outwash, beneath a sewer with only inches of clearance, beneath water mains, and below a high-pressure gas main. Probe holes were drilled using horizontal di- rectional drilling to provide greater certainty that there would be no im- penetrable obstacles to the drives be- neath the Belt Parkway. The project was completed successfully, at a cost less than the original estimates. By eliminating a wastewater bottleneck, combined sewer overflows will be significantly reduced and the water quality of Bergen Basin and Jamaica Bay improved. Stantec South Surrey Interceptor Johnston Road Section – Phase 2 The South Surrey Interceptor John- ston Road Section – Phase 2 project consists of an approximately 800 m (2,624 ft) long , 3,050-mm (10-ft) di- ameter gravity sewer in Surrey, Brit- ish Columbia. Currently under con- struction, the interceptor will collect sewage from South Surrey, White Rock and Langley and convey it to the Annacis Island Wastewater Treat- ment Plant . The contractor elected to use a 3.6-m (11.8-ft) outer diameter microtunnel boring machine to in- stall the reinforced concrete pipe us- ing two straight drives and 2 drives with horizontal curves. This is be- lieved to be the largest microtunnel project (by diameter) ever completed in North America. The longest drive will be approximately 355 m (1,164 ft). Key project challenges include tunneling beneath business parks and city streets, bouldery ground, and tunneling near several utilities. Stantec 's responsibilities included performing the geotechnical inves- tigation, preliminary and detailed design, and contract administration and inspection during construction. AECOM Capital Regional District Wastewater Treatment As part of a joint venture, AECOM is providing a new state-of- the-art wastewater treatment plant (WWTP) on a point of land across the harbor from Victoria, British Columbia un- TOP 50 T R E N C H L E S S E N G I N E E R I N G F I R M S THE TOP 10 IN TRENCHLESS ENGINEERING Leading Design Firms Apply Innovative Trenchless Solutions to Big Projects in 2018

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