Last September, tunneling was used to replace a 48-inch diameter corrugated metal pipe (CMP) culvert that had been in service for 25 years on Route 4 in New Castle County, DE.
This was the first use of tunneling and pipe jacking of storm sewer in the history of the Delaware Department of Transportation (DelDOT). The project proved to DelDOT that tunneling and jacking using reinforced concrete pipe is a cost-saving construction alternative to the open-cut method.
For this project, DelDOT received the 2009 American Concrete Pipe Association’s Project Achievement Award. The award is based upon public involvement and education, use of new materials or large diameter concrete pipe or precast boxes, use of new technologies, innovation, complexity, cost effectiveness and environmental benefits.
In the summer 2008, Eastern States Construction of Wilmington DE, contacted Tenbusch Inc. of Lewisville, TX, to explore the cost and availability of equipment to tunnel the job. Eastern States submitted a proposal to replace the existing CMP with 54-inch diameter RCP, as originally specified, by tunneling instead of open cut. The cost savings to the state was approximately 30 percent of the original contract amount.
Tenbusch supplied Eastern States Construction with a tunneling shield and a 250-ton hydraulic jacking unit. Rinker Materials – Concrete Pipe Division (CEMEX) supplied the concrete pipe. The tunneling shield protected the men as they removed the existing CMP and excavated as necessary to accommodate the new RCP. As the tunnel was excavated, the hydraulic jacking unit provided the necessary force to jack the 54-inch RCP column under the roadway. The contract allowed 75 days to complete the project. Eastern States took only 15 days to tunnel the culvert.
Al Tenbusch, president of Tenbusch Inc. says, “The problems associated with the lowest cost and short service life products chosen for culverts and sewers in years past are beginning to escalate. Tunneling with long service life products can provide states, counties and cities with a less-expensive option to rehabilitate or replace deteriorating culverts with minimal disruption to motorists.” 972.221.2304, www.tenbusch.com