Photo Credit: STRUCTURAL
The Hickey Run Aerial Sewer Crossing located in the U.S. National Arboretum in Washington, DC, was significantly impacted by record-setting flooding and erosion. Inspections of the 51-in diameter, concrete encased Eastside Interceptor revealed spalled concrete at the upstream abutment and a compromised foundation. Along the embankment, crews discovered an eroded void beneath the footer and the exposed backside which had been subject to severe weather and record-high creek levels.
DC Water sought an emergency design-build repair to restore capacity, extend the life of this asset, and protect against future degradation. The Department of Energy and Environment approved a “permitting later and urgent repair first” approach. The design-build approach led by DC Water brought together the project team to collaboratively develop a multi-faceted solution for the structural repair of this critical wastewater structure. The in-situ rehabilitation consisted of 58 LF of the aerial sewer crossing and critical support structure.
Crews performed concrete enlargement and repairs. Micropiles and new piers were installed to stabilize the foundation. CFRP and GFRP strengthening systems were installed on the pipeline encasement. The team provided site access and implemented environmental and safety controls to perform repairs with little impact to the environment.
Leveraging Design-Build for Emergency Repairs
DC Water was able to manage the immediate need for structural rehabilitation by leveraging design-build delivery. The design-build approach allowed the project team to collaboratively develop a cost-effective, multi-faceted renewal solution. With this approach, the team was able to maintain the integrity of the environment by acting quickly to prevent pipe failure and contamination of the creek, while also limiting the disruption to flora and fauna. Environmental and safety controls were implemented to mitigate these risks. In addition to achieving cost and schedule goals, the structure’s service- life was extended by 50 years.
Design-Build Team
| Client/Owner: | DC Water |
| Engineer: | Structural Technologies |
| Design-Build Contractor: | Structural Preservation Systems, LLC |
| Specialty Contractors: | Avon Corporation |
| Construction Duration: | 6 Months |
| Project Cost: | $2.1 Million |
