HCFCD Raises Questions about Army Corps’ Buffalo Bayou Interim Report

In October, I reported on the Army Corps’ 210-page Buffalo Bayou and Tributaries Resiliency Study (BBTRS) Interim Report.

First look at Corps’ alternatives to reduce flooding on the West Side of Houston

Harris County Flood Control District (HCFCD) provided eight pages of detailed comments on it. HCFCD shared concerns expressed by the public about certain alternatives such as the widening of Buffalo Bayou. HCFCD also expressed that they hoped the Corps would not prematurely rule out some alternatives. The biggest: a flood tunnel.

HCFCD felt the Corps needed to put a sharper pencil to tunnel cost estimates and weigh those against the environmental impact/costs of widening Buffalo Bayou.

High-Level Concerns

Flood Control expressed six high-level concerns:

  1. The Corps seemed to ignore a wealth of studies conducted by HCFCD on the study area and arrived at different conclusions.
  2. The Interim Report presents benefits only in terms of annualized monetary values. “Water surface elevation reductions, numbers of structures benefitted, and the locations of benefits are curiously absent in the main report.” HCFCD believes some cost estimates should be revisited. “In particular, we believe the Interim Report overestimates stormwater tunnel costs and underestimates costs, both environmental and economic, of large-scale conveyance improvements to Buffalo Bayou.”
  3. Estimated project costs are so high, and their benefit/cost ratios so low, that HCFCD anticipates funding challenges on both the federal and local levels. The 2018 Flood Bond did not allocate money for any of the alternatives proposed by the Corps. “However, smaller scales of the alternatives could be more affordable and acceptable to the public, and as a result, are more likely to be funded and implemented. These variations, both for structural and nonstructural alternatives, warrant more attention moving forward.”
  4. The District recommends that “the full array of alternatives be consistently evaluated for environmental impacts, both beneficial and adverse. For example, we see opportunities for habitat restoration associated with the Addicks and Barker excavations…” But “…environmental impacts associated with the Buffalo Bayou channel improvement alternative are underestimated…” HCFCD believes that closer environmental inspection, right-of-way evaluation and public opposition, Buffalo Bayou expansion will not be deemed plausible.
  5. The Corps’ report acknowledges that a non-structural alternative exists to improve water control operations at the existing reservoirs and to update the reservoir’s Water Control Manual. Unfortunately, the Corps does not elaborate much on these alternatives, but HCFCD believes “Operational changes could reduce the scale of alternatives necessary to achieve the desired level of resilience. Plus, modified operations alone could reduce flood risks and mitigate erosion and slope failures along Buffalo Bayou downstream of the reservoirs, both of which are problems that the study aims to address.”
  6. Purchasing additional property upstream of the current reservoirs would require non-federal cost sharing. The Flood Control District questions the rationale for “commingling ownership responsibility with the Corps.” The District says, “We need to more fully understand why the Corps feels it is our responsibility to participate financially should this alternative move forward.”

Detailed Concerns

The report then goes into eight pages of amazingly detailed comments in a spreadsheet format. Most amount to requests for more information or clarification.

For instance:

Buffalo Bayou Widening: Costs vs. Benefits

“What are assumed costs for stream habitat loss associated with deepening Buffalo Bayou 11‐12 feet? How many acres of land would have to be acquired for this alternative, at what cost? How many parcels and/or structures? Please also summarize benefits of this alternative?”

HCFCD comments also include several suggestions:

Excavating Reservoirs: Way to Reduce Costs

Re: additional excavation of the Barker and Addicks reservoirs to increase their storage capacity, HCFCD said the following. “We feel there is an opportunity to further value engineer this alternative by stockpiling material within the reservoirs to create hills which will help limit haul costs.”

Tunnel Cost Estimates Too High; Need to be Weighed Against Tradeoffs

Re: the construction of tunnels to create an alternate route for floodwaters to Galveston Bay, HCFCD said this. “The tunnel cost is shown as $6.5B to $12B. This is significantly higher than estimates prepared during the District’s Phase 1 tunnel study…” The District estimated that a tunnel capable of conveying 10,000 cfs from the reservoirs to the Houston Ship Channel would cost $3 to $3.5 billion including a 50 percent contingency. That’s about a half to a third of the cost estimated by the Corps.

HCFCD fears that tunnels may have been prematurely eliminated from evaluation. Especially because environmental impacts associated with widening Buffalo Bayou were not considered in the decision to drop the tunnels from consideration.

Posted by Bob Rehak on 12/4/2020

1193 Days after Hurricane Harvey