CDM News - August 2007 - (Page 7)

“Relying on microtunneling helped minimize the project’s impact on these residents and the community … [it] was a highlight of the project’s success.” — Emily A. Baker, P.E., city engineer graphic ridge line, with the depth of cover for the new storm sewer ranging from approximately 8 to 25 feet. As such, trenchless construction methods were reviewed, with ultimate selection of microtunneling—an extension of the pipe jacking technique that uses a remotely controlled microtunnel boring machine. “Using traditional, open-cut construction methods would have required deep excavations and the use of extensive excavation support systems, while causing signiﬁcant disruptions to property owners, commuters, and the general public,” explained Christopher Patackis, P.E., BCEE, CDM project manager. Inconveniences to the public during construction of this project were magniﬁed due to the tight construction work area, conflicts with existing utilities, and proximity to existing residential structures. “Relying on microtunneling helped minimize the project’s impact on these residents and the community,” continued Baker. “This is a dense area with on-street parking and houses located close to the road. Eliminating unnecessary construction was imperative and a highlight of the project’s success.” Final design of the new combined sanitary and storm sewers included construction of an estimated 3,300 linear feet of pipe, ranging from 10 to 72 inches in diameter, with approximately 750 linear feet of new 48-inch diameter storm sewer installed through microtunneling. Microtunneling, which began in June 2005 and was accomplished in a single drive from a constructed downstream jacking pit, was completed in 12 working days, with a best singleday production of 100 feet. Once under way, construction was affected by the discovery of petroleum-contaminated soil and groundwater in the vicinity of the microtunneling jacking pit. A work plan was developed for the sampling, testing, and disposal of petroleumcontaminated soils removed as spoil from microtunneling operations, soil from excavation of the jacking pit, and petroleum-contaminated groundwater. “The use of trenchless construction methods provided additional benefits after discovery of petroleum-contaminated material, since production rates were not significantly compromised and direct contact with contaminated material was reduced,” added Patackis. A comprehensive public communications program was also implemented throughout the project life cycle, keeping residents abreast of the project during the study, design, and construction phases. Residents were educated through a variety of sources, including newspaper articles, direct mailings, public meetings, and the city’s Web site. “Because the area is so urban and residential, it was critical for us to keep our residents informed,” explained Baker. “The communications program provided a point of contact for questions, scheduling information, and peace of mind about the project.” Since the project’s completion, a number of signiﬁcant rainfall events have occurred, including a 200-year, 6-hour duration storm in June 2006. Despite these events, no flooding has been reported in the project area—helping ensure this historic community continues its reign as a residential, commercial, and tourist destination for years to come. | Elizabeth A. Sprouse For information on CDM’s work using trenchless technologies, visit www.cdm.com/trenchless. Stakeholder Communication Contractors used micro-tunneling during the construction of the new storm sewer, eliminating the need for deep excavations and support systems. 7 http://www.cdm.com/trenchless

Table of Contents Feed for the Digital Edition of CDM News - August 2007

Contents Envisioning Tomorrow’s Dublin Initiative & Innovation Stabilize Mercury Mines Preserving Old Town Alexandria Taking a Hard Look at Concrete Corrosion Perspective: Harnessing Bioenergy Engineering Better Lives CDM Announces Award-Winning Projects People Highlights

CDM News - August 2007

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