U.S. Army Corps of Engineers Interim Report
Interim Report for Public Comment
The U.S. Army Corps of Engineers (USACE), with non-federal sponsor, the Harris County Flood Control District (HCFCD), completed its Interim Feasibility Report for the Buffalo Bayou and Tributaries Resiliency Study (BBTRS). The study was released to the public on October 20, 2020.
The study evaluated the feasibility of reducing flood risks along Buffalo Bayou and its tributaries, both upstream and downstream of Addicks and Barker dams. It also included a Dam Safety Modification Evaluation on Addicks and Barker dams.
While no definitive recommendations were made, the Interim Report was roundly criticized for its key findings, that is, the construction of a new reservoir in the Katy Prairie and the potential displacement of residents along Buffalo Bayou.
In December 2021, USACE and HCFCD announced a new path forward for the BBTRS. Following the release of an Interim Report in October 2020, the Assistant Secretary of the Army for Civil Works approved a schedule extension and budget increase for the study. Additional federal funds, in the amount of $1.8M, paired with engineering technical services to be provided by HCFCD using $3.367M in funds from Harris County Commissioner Precincts 3&4, will allow for further study of alternatives, particularly development of a tunnel alternative for consideration in the study.
The tunnel is a central part of the Buffalo Bayou Community Plan prepared by Houston Stronger, a consortium of businesses and civic organizations in Harris County. Other proposed options include increasing storage within Barker and Addicks reservoirs and increasing storage in the upper Addicks and upper Cypress Creek watersheds. With this additional work, a Draft Report is scheduled to be released in the Fall of 2022, and study conclusion in December of 2023. For more information on the BBTRS please visit: https://www.swg.usace.army.mil/Missions/Projects/BBTRS
Buffalo Bayou Community Plan
In 2020, the U.S. Army Corps of Engineers (USACE) issued the Interim Report for the Buffalo Bayou and Tributaries Resilience Study favoring two solutions, channelizing Buffalo Bayou and constructing a reservoir on the Katy Prairie in the Cypress Creek Watershed. However, both face heavy community opposition. Houston Stronger provided critical feedback to USACE and offered a substitute plan known as the the Buffalo Bayou Community Plan that provides a road map to achieve effective flooding solutions with community support.
Preliminary Engineering Study for Large Diameter Tunnels
Phase One of this project provides a high-level look into the feasibility of constructing large diameter deep tunnels to help move stormwater out of Harris County. The study is an initial phase, focused on determining the applicability of tunneling considering the soil types and geotechnical challenges specific to Harris County, evaluating hydraulic capacity and impacts, scheduling and cost projections, and comparing with other active and completed tunnel projects. Summary findings are:
- Geotechnical conditions do not appear to present any remarkable nor non-negotiable concerns.
- Geologic faults may require special design and construction considerations if crossed by the tunnel; not considered fatal flaws.
- Tunnels can move a significant rate of stormwater operating by gravity as an inverted siphon.
- Tunnel cost, including a 50% contingency, for a 10-mile-long, 25- and 40-foot diameter tunnel is approximately $1 billion and $1.5 billion respectively.
In Spring 2022, the Flood Control District completed Phase Two of this feasibility investigation. The purpose of Phase 2 was to identify unmet flood mitigation needs in Harris County’s watersheds and – if possible – develop distinct tunnel concept(s) that would meet those needs, while providing sufficient benefit to justify their construction.
During Phase Two, it was determined that a tunnel system, rather than one or more individual tunnel alignments, should be the focus of further study. This additional study would be needed before a final decision is made on whether to move forward with adding tunnels to Harris County’s stormwater management system.
The Flood Control District could begin Phase Three in the Spring of 2023, once project scope is determined. It is expected that Phase Three would consider further engineering analyses (validation of assumptions, hydrologic and hydraulic modeling, geotechnical investigations, and evaluation of active vs passive systems). It will examine the countywide economic benefits of adding a tunnel system to our current stormwater management network, as well as the process needed to integrate the tunnel system within existing neighborhood drainage, bayous and stormwater detention basins.
Additionally, Phase Three will explore funding strategies to pay for a tunnel system. Community engagement will continue to be a priority, so additional meetings are planned. Once begun, Phase Three of the feasibility study is expected to take approximately three years.
Greater Houston Flood Mitigation Consortium
The Greater Houston Flood Mitigation Consortium is a group of leading researchers from a number of academic institutions who came together to compile, analyze and share a rich array of scientifically-informed data about flooding risk and mitigation opportunities.
The purpose of the research was to provide our public officials with the best possible information available in their deliberations - and to provide residents with information that will help them better understand and advocate for the options that work best for their communities.