Pantano Wash Bank Protection: Speedway Blvd. to Tanque Verde Rd.

On July 30, 2006 a major storm event destroyed 300 linear foot section of gabion rock basket bank protection adjacent to the Kolb Executive Park, placing the business park buildings and parking structures in potential danger. Across the bank a 300 linear foot section of rock and rail bank protection for the Pantano Townhomes also failed, in the vicinity of a major Tucson Electric Power transmission pole. Following the storm the Pima County Regional Flood Control District (RFCD) and Federal Emergency Management Agency (FEMA) personnel inspected the damaged and noted that the toe of the grade control structure immediately upstream of the Executive Park and the soil cement bank protection adjacent to the City of Tucson Mullins Landfill could also fail. RFCD and FEMA provided temporary rock rip rap bank stabilization in December 2006 to reinforce the failed and weakened sections of bank protections and the grade control structure.

The July 30th, 2006 event passed 15,900 cubic feet per second (cfs) of flood water under the Broadway Boulevard Bridge. This storm event represented a 30 to 35 year flood event for the Pantano Wash, or an annual probability of 3 percent for having a flood event of this flow magnitude or larger.

The RFCD hired Psomas consulting engineers to evaluate the stability of the existing bank and bank protection on the Pantano Wash between Speedway Boulevard and Tanque Verde Road and to develop plans for Phase 1. Phase 1 will provide a permanent replacement for the failed gabion, rock and rail bank protection and grade control structures, utilizing FEMA funding. Phase 2 and 3 of the project will include building soil cement extensions under the existing bank protection that did not failed for the sections downstream and upstream of Phase 1, providing additional grade control structure at Tanque Verde Road Bridge, constructing pedestrian underpass ramps at Speedway Boulevard and Tanque Verde Road and developing linear park improvements for the entire reach. Phase 2 and 3 will include a paved multi-use pathway and introduce native vegetation in select sections next to the pathway.

Phase 1 is currently schedule to begin construction in January 2010 and be completed by September 2010, utilizing FEMA and County funding. Construction of Phase 1 is estimated to cost $4.08 million, and the total project cost for all three phases is currently estimated at $8.35 million.