City Solves a Failing Sewer Problem with HDD and Drill Drop Methods


City Solves Failing Sewer Problem with HDD and Drill Drop Methods

Authors:

Chris Petta, PE, Mott MacDonald, Cleveland, Ohio
Rory Ball, PE, Mott MacDonald, Cleveland, Ohio
Glenn Duyvestyn, PE, PhD, Mott MacDonald, Houston, Texas
Don Ramm, PE, City of Independence, Ohio
Clark Merdes, PE, City of Independence, Ohio

Abstract: The City of Independence recently completed a challenging gravity sewer project that included an uphill approximately 2,800-foot long horizontal directional drill (HDD) crossing through an S-curve. A 24-inch diameter bore was drilled to install 16-inch outer diameter, DR7.3 HDPE product pipe maintaining a minimum one (1) percent slope to sustain gravity sewer flow. Independence Excavating (Indy-X) was retained as the Prime Contractor, with DRS Enterprises and McKinney Drilling hired on as the Horizontal Directional Drilling (HDD) and vertical drilling contractors, respectively. The project rerouted an existing sewer line that was in jeopardy of failure with no option to implement bypass flow. At the downstream end of the HDD, the project installed a 50-foot deep drill drop structure tapping into the existing 7.5-foot internal diameter Cuyahoga Valley Interceptor Sewer (CVI), which is located approximately 350 feet from the Cuyahoga River. This paper provides insight into how some of the design and construction challenges were evaluated and conquered on the project. Design challenges included determining the most appropriate and cost-effective construction methods, tie-in location, routing, and vertical/horizontal alignments.

Trenchless construction methods evaluated as part of this work included: HDD, microtunneling, pipe jacking, auger bore, and pipe ramming. HDD was selected as the preferred construction method with a final alignment consisting of: a horizontal S-curve, a slight compound curve, drilling within a narrow easement, and an elevation difference between HDD entry/exit of approximately 90 feet. In addition, significant coordination was completed with the Northeast Ohio Regional Sewer District (NEORSD) regional sewer district regarding the new connection location, drop structure design, construction sequence, and tap- in procedures. Trenchless construction challenges included, but were not limited to, having limited HDD workspace due to surrounding delineated wetlands, controlling surface runoff, torque requirements for uphill drilling and reaming, and drilling fluid management and dealing with an inadvertent return. Once the HDD product pipe was installed, a couple other construction challenges encountered were: drill drop structure support of excavation (SOE) issues and HDPE product pipe partial beads that were not completely removed; which both were overcome by adapting means and methods and using creative solutions. Other challenges, not directly associated with the trenchless component of the project included managing additional project costs and local resident expectations.

Publication Date: 2018

Presented at:
NASTT’s 2018 No-Dig Show Palm Springs, California
March 25-29, 2018 | Paper Number: MM-T2-03


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