Roslindale, MA
MWRA, High Level Sewer
Scope/Solutions
The High Level Sewer (HLS) is a masonry conduit built around 1901. Following a large rainstorm, the HLS developed internal pressure that caused water to overflow through the manholes and flood parts of the Roslindale neighborhood. The manholes were bolted down to prevent future flooding. A couple years later, during a heavy rain storm, the HLS was pressurized again, resulting in failures of manholes, cracking of the masonry conduit, movement and cracking at bends in the sewer line, and significant leakage. SGH was retained to perform an emergency condition assessment, evaluate risk of pressurization during future storm events, and develop a repair program.
Highlights of our work on this project include the following:
- Performed manned internal inspection of approximately 1,600 ft of HLS while in operation
- Inspected the exterior of the HLS in eight test pit excavations
- Evaluated rainfall data and hydraulic analysis before and after a connection bypass to Stony Brook planned by MWRA to lower water levels during a severe storm
- Performed structural evaluation and damage assessment of the conduit by finite-element soil-structure interaction analysis
- Determined risk associated with pressurization of the HLS in future storms before bypass installation
- Developed an emergency response procedure
- Identified two areas that needed emergency repairs, prepared design and bid documents, hired the contractor, performed bid evaluations, and monitored construction
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Project Summary
1998
Completion Date
Solutions
Failure Investigation
Services
Structures | Advanced Analysis
Markets
Infrastructure & Transportation
Client(s)
Massachusetts Water Resource Authority
Specialized Capabilities
Repair & Strengthening | Buried Infrastructure | Computational Mechanics
Key team members
Additional Projects
Northeast
Court Square Parking Garage
Set in the urban area of Court Square, the new 193-space parking garage was scheduled to be built following the demolition of an existing structure. SGH was prime consultant, function designer, and structural engineer of record for the project.
Northeast
Charlestown Bus Facility Shoreline Stabilization and Yard Improvements
The existing steel sheet pile seawall, which protects the facility from flooding and river erosion, was severely deteriorated. SGH investigated the failing seawall, including the pavement and soil loss behind it, and designed new shoreline stabilization and drainage systems.