Austin’s Brazos Duct Bank

Project Background

Austin’s Brazos Duct Bank project aimed to provide an accessible and maintainable duct bank system to provide power to the downtown grid. It involved designing and installing a series of nine 5-inch conduits within a duct bank using the micro-tunneling method. This project was crucial to Austin Energy’s downtown distribution energy plan to provide a more resilient energy system. Its location on the banks of Lady Bird Lake made it particularly important to minimize the impact on the area.  

 HVJ was selected for this project through the City of Austin’s (COA) qualification-based selection process, acting as a sub-consultant to Jacobs. Our role was to perform geotechnical investigations, including a comprehensive Geotechnical Data Report. This report would be pivotal for the Project Tunnel Engineer in preparing project specifications and the baseline report.  

Given the project’s reliance on micro-tunneling, the city needed to engage a geotechnical firm with in-depth knowledge of the local geological conditions and expertise in specialty drilling and laboratory testing. HVJ’s team brought this expertise to the table, leveraging deep experience with geologic formations in the area, in-situ packer testing, and laboratory testing required for the specialized tunneling project. 

Practice: Geotechnical Engineering

Sector: Energy

Location:  Austin, TX

Services: Geotechnical Field Exploration and Laboratory Testing


The Problem

 Several unique challenges required innovative solutions and extensive pre-planning. First, the location is in a busy downtown area with a portion traversing through a cherished park near the lake. We needed to minimize disruptions to local businesses and traffic. Ensuring the preservation of natural resources and landscaping in the park and nearby business centers was a top priority. Another challenge was the terrain at the project site being unsuitable for a conventional truck-mounted rig, which is typically used for drilling borings. To address this, a track rig was used to drill the borings, but careful handling and pre-planning were required to mitigate rutting. 

The Goal

Our goal was to conduct geotechnical investigations with minimal disruption to local businesses and traffic. Achieving this goal was a multi-step process. We first needed to obtain city permits, coordinate with the Parks and Recreation Department, and ensure adherence to all city regulations. We then needed to communicate with local businesses to outline the plan, prepare them for what to expect, answer questions, and determine optimal blackout hours to minimize disruption. Before drilling could begin, we did extensive pre-planning and preliminary site visits to develop a strategy for strategic mat placement and rig arrangement to reduce rutting. We developed a traffic control plan to keep traffic flowing as smoothly as possible during work 

Our Solution

We used several strategies to implement a comprehensive solution to this project’s challenges: 

  • We used a track rig for drilling that allowed us to access uneven terrains. The rig was equipped to perform packer testing to determine the permeability of the bedrock. 
  • We conducted preliminary site visits to identify site constraints, arrange logistics, and ensure we had a plan to overcome challenges such as protecting the landscape. 
  • Before starting, we held a site meeting with the client, project stakeholders, and representatives from nearby businesses. We presented our contingency plans, established clear lines of communication, answered questions, and set realistic expectations for any potential issues. 
  • We employed an experienced field engineer to oversee field exploration. This engineer maintained constant contact with the Project Manager. 

The Results

Our extensive background work before beginning drilling enabled a smooth project. There were no surprises for the client or businesses during the field exploration process. The all-stakeholder site meeting was particularly effective because we responded directly to their questions or concerns before work started.  

Technically, the field exploration was completed successfully. Our team members used their experience and knowledge of the area to determine that single packer testing and a point load test would be most suitable and reliable.  

We were honored to work with the Jacobs team on this high-profile project. The Jacobs team provided invaluable assistance and collaboration. HVJ takes pride in owning the solution for any challenge that may arise, and in this case, strong communication and pre-planning diligence enabled a successful outcome.  

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