We worked next to and below fragile, historic brick sewers to underpin and protect them during the subsequent tunneling operations for the construction of the Main Pumping Station Diversion structure.  

The Project

The DC Clean Rivers Project is a major sewer and water infrastructure project intended to minimize sewage outfall to nearby rivers within the Washington, DC metro area. Division I – Main Pumping Station Diversion Structure is a new structure included in the project that connects existing brick sewers to the proposed main pumping shaft.  

The Challenge

Construction of the Division I shaft required deep earth retention constructed in relatively poor soils. Excavation to a depth of approximately 25 feet caused concerns about water inflow into the shaft and the stability of the soft soils near the shaft and tunneling operations as well as below the existing sewer lines.  

The Solution

HBI’s jet grouting provided underpinning and support to the existing utilities, increased passive resistance to the earth retaining system, and reduced water inflow into the excavation.  Additional jet grout columns were strategically added to facilitate the excavation and installation of additional utilities. 

Project Facts


DC Water

Main Contractor(s)

Corman Construction, Inc.

Keller Business Unit(s)

Hayward Baker


Whitman, Requardt & Associates, LLP