In a statement, the Flood Control District of Maricopa County announced that it has been authorized to initiate the design of the rehabilitation project by the Maricopa County Board of Supervisors.
The rehabilitation – which in total is expected to cost US$98M – focuses on the 34ft-high McMicken Dam located between US 60 and Peoria Ave, and the McMicken Outlet Channel and McMicken Outlet Wash in the City of Surprise and unincorporated Maricopa County. The Flood Control District owns, operates and maintains the dam and outlets, which protect more than 80,000 residents and $6B in property from flooding hazards.
The resolution to move ahead with design places on hold a 2004 Feasibility Cost Share Agreement between the District and the US Army Corps of Engineers (USACE). Since 2004, the District has worked with USACE to develop a plan for the rehabilitation project to correct deficiencies in the physical structures, protect the structures from ground subsidence and earth fissures, and extend the useful life of the structures. The goal is to improve the 55-year-old dam and outlets to current dam safety standards.
The agreement stipulated USACE contribute $2.3M toward the total $4.9M cost of the design of the project. To date, USACE has delivered $300,000 due to limited available federal funds. By placing the feasibility cost share agreement on hold, the District can proceed without USACE to implement solutions to address the current deficiencies while still keeping viable the possibility of future federal funds.
The District’s Rehabilitation Project design phase is anticipated to be completed in 2014. The design stems in part from the District’s Wittmann Area Drainage Master Plan study, which identified McMicken Dam and its outlets as integral parts of a larger plan to reduce flooding hazards in northwestern Maricopa County.
“McMicken Dam has been an essential component of the county’s flood control infrastructure since 1956,” said Maricopa County Supervisor Max Wilson, who represents District 4 in which the dam is located. “The decision to move ahead on improvements to the dam and outlets ensures citizens, businesses and agriculture will be protected from flooding, and further emphasizes the county’s commitment to the long-term viability of Luke Air Force Base.”
“This is one of seven rehabilitation projects being pursued by the District to upgrade key structures in our inventory of 22 flood control dams,” said Tim Phillips, the District’s chief engineer and general manager. “In our 20-year long-range plan, these projects are anticipated to make more than $200M in improvements to a system of dams that provide critical regional flood hazard protection.”
In 1951, prior to the construction of the McMicken Dam Project, Luke Air Force Base suffered significant damage due to heavy flooding. The dam and outlets were constructed by USACE in 1956 in direct response to this flooding event and other floods that damaged agricultural land. Today, the structures provide enhanced flood protection for property located directly downstream, including Luke Air Force Base and significant portions of the Surprise, El Mirage, Sun City, Youngtown, Litchfield Park, Avondale, and unincorporated areas of Maricopa County in the West Valley.
During a storm, rainfall runoff from Trilby Wash and other tributary washes is detained behind the dam and released in a controlled fashion along the outlet channel and outlet wash to its final outfall into the Agua Fria River. Without the Project in place, this stormwater would travel through residential subdivisions, business development, and the air force base facility.
