By Lynda Myer
In order to construct a deep tunnel and new sewer facilities in Alexandria in Virginia, US, North American sister companies Nicholson Construction and Berminghammer are collaborating on piling works on this project.
Including a new combined sewer overflow (CSO) tunnel to manage four overflow areas, advancing the US$454M (£367M) River Renew project is up to Alexandria’s wastewater treatment provider, Alex Renew.
The scheme is due to help prevent around 530M.l of combined sewage – a mixture of rainwater and sewage – from polluting Alexandria’s waterways every year.
While in November 2020, the contract of design and constructing the River Renew tunnel system was awarded to a Traylor-Shea joint venture (JV), Pittsburgh-based Nicholson’s portion of the work for the JV includes the installation of a tangent/secant pile support of excavation (SOE) system for the outfall structure adjacent to Alexandria’s water treatment plant.
The 120 EA, 0.6m auger cast, or continuous flight auger (CFA), piles drilled up to approximately 15m in depth, will be the contents of the SOE.
For the drilling, Nicholson will use a Berminghammer H-28 leads and drill mounted on a Manitowoc 999 crane.
Considering that supporting the long reaches (18m) required for the River Renew project that are not possible with traditional rigs is important, Nicholson purchased Berminghammer’s H-28 system for CFA drilling.
Berminghammer was able to provide the H28 system to meet a very quick turnaround for the works, which began this month.
According to Nicholson Construction project manager Michael Bianco: “We’re really leveraging the benefits of belonging to this global group and the experience and technologies that are available to us from our sister companies.”
“The Berminghammer team has been very helpful in this effort – and with their help, we can effectively do our part for this massive infrastructure project that is going to provide clean waterways for millions of people in the Virginia metro area,” added Bianco.
Locating at over than 30m beneath the city, the Waterfront tunnel with 3.2km length and 3.7m width is being excavating by Tunnel boring machine (TBM) Hazel, which was lowered into its launch shaft last August. Its progress was 91m to date, excavating 3,000t of soil. The Herrenknecht manufactured TBM weighs 345t and has a diameter of 4.47m.
The Traylor-Shea design-build team has been supported by Jacobs Engineering and Corman Kokosing Construction.
The determined date for completion of River Renew project is late 2025.
