The Flood Control District operates and maintains 22 flood control dams which provide highly beneficial flood protection for significant portions of Maricopa County. Most of these dams are the main flood control features of federal flood control projects of which the District was the local sponsor.
Dam Safety Program
The District's Dam Safety Program is made up of three major components over and above normal operation and maintenance activities:
1. Recurrent Dam Safety Activities
Recurrent Dam Safety Activities primarily include: dam safety inspections, outlet pipe inspections, field surveys, land subsidence monitoring, earth fissure monitoring, and development and updating of Emergency Action Plans. Dam safety inspections are performed on an annual basis by District staff. Inspections of outlet pipes by video camera are performed every five years. Field surveys of the dams are required to monitor physical changes to the dams due primarily to embankment and foundation settlement and land subsidence. Most dam surveys are performed under professional consultant service contracts. Land subsidence occurring at and in the vicinity of dams is monitored through use of an engineering tool developed from satellite imagery known as Interferograms which can detect small-scale vertical ground movements over very large areas. Monitoring for the development of new earth fissures is performed through instrumentation installed at identified earth fissure risk zones at dams. Emergency Action Plans are required for all dams and are updated periodically under consultant contracts.
2. Structures Assessment and Repairs
The Structures Assessment component of the Dam Safety Program assesses and evaluates the physical condition of the District's 22 dams and related features to assure continued compliance with current regulations, and to implement short-term and interim-term measures for the safe operation and proper functioning of the dams required beyond normal operations and maintenance requirements. Phase I Assessments are completed and provide an overall evaluation of the dams pertaining to dam safety and flood protection. Under Phase II of Structures Assessment, site-specific dam safety issues and potential dam safety issues are investigated and repaired or corrected as needed. More extensive interim dam safety repairs are performed as required under Capital Improvement Program (CIP) construction contracts such as the McMicken Dam Fissure Risk Zone Remediation (FRZR) Project.
3. Dam Rehabilitation
Thirteen District dams are currently identified for overall rehabilitation or replacement due to issues of dam safety, urbanization and flood protection. Dam rehabilitation design and construction contracts are programmed in the CIP. The dam rehabilitation component of the Dam Safety Program is anticipated to have a total cost of $250 million over a 25-year period.
Right-of-Way Use Permits
The District owns and maintains flood control facilities and land throughout Maricopa County. In order for an entity to access or use this facility or land, a right-of-way permit must be obtained. The District reviews submittals for proposed utility and roadway crossings at District flood control dams, and provides field inspections of construction by others of non-District utilities and facilities at District-owned structures and property.