Mohave County works to mitigate flood risks
Mohave County works to mitigate flood risks
Mohave County is located in the northwestern part of Arizona. Like many other parts of the state, Mohave County has small to significant flooding events throughout the year. Many communities in the county are located on (or near) a floodplain, meaning they have higher levels of flood risk.
In the Fort Mohave community, rapid growth and development of homes and streets have changed the natural flow of water, preventing it from naturally being absorbed into the ground. Inadequate drainage is also common in many areas where people live. Winter precipitation and monsoon storms tend to bring heavy rainfall to the area, stressing flood control measures.
The Sunrise Vistas community has a channel along the east side of the subdivision. The channel capacity is insufficient to hold heavy water flows. When exceeded, the water spills into backyards, flooding the residential structures.
“The Sunrise Vistas subdivision was built at a time when construction standards and permitting requirements were less stringent than they are today. The flooding risk was not studied in any significant detail in the design process and county involvement in the design and construction was minimal,” said Randall Gremlich of the Mohave County Flood Control District. “As a result, flooding problems developed soon after construction. In an effort to mitigate the flooding problems, the developer later built two small channels on the upstream sides of the development to route water around the homes. These small channels helped in minor storms but there was still damage to the vulnerable homes in larger storms.”
According to Gremlich, Mohave County started plans to enlarge the channels to protect the development from flooding and erosion in the event of a 100-year flood. They began to obtain land for the channels in 2010. “However, funds for construction of the project were reduced due to the recession and other projects with a higher priority. The project was then put on hold.”
In 2014, Mohave County Flood Control District applied for a Pre-Disaster Mitigation Grant (PDM) from the Federal Emergency Management Agency (FEMA) through the State of Arizona to reduce or eliminate flooding and erosion risk to people and property by mitigating along the perimeter of the housing subdivision.
The PDM grant is an annual non-disaster program used to implement natural hazardous mitigation. Hazard mitigation is when a community/government takes steps to reduce or eliminate risk to people and/or property.
“The grant was awarded in the amount of $437,628.75 with a match requirement from Mohave County of $145,876.25,” said Gremlich. “The grant allowed for the construction of the channel widening on the east side of the subdivision. [The channel widening that was designed for the north side of the development is still on hold and is expected to be built in the future.]”
The Arizona Department of Emergency and Military Affairs (DEMA) assists its partners with grant applications, and when approved, works with them through the project. A DEMA Project Specialist was assigned to work with Mohave County during the extent of the project.
“Our role during the mitigation project is to oversee a project that has been awarded. We first start off with a site inspection where pictures are taken before work begins and a meeting is conducted going over expectations and what is required of the applicant,” explained Erik Anderson, DEMA Mitigation Project Specialist. “We require the applicant to fill out quarterly reports. We ensure they are following their procurement procedures and following FEMA rules as to how they award contracts. We audit their force accounts (look over time sheets and equipment logs), and keep in contact with them during milestone events.”
In February 2016, work began on the channel to accomplish two things: widen the channel in order to move excess runoff flows away from the subdivision, and to install erosion protection. Over the next few months, the channel was widened and concrete grade control structures were installed to help the excess water flows. Rip rap (rock or other material) was placed along the edge/sides of the channel to protect the east property line of the subdivision from erosion.
The project was finished in August on 2016. Not only will the residents be at a smaller risk for flood damage, but the county and residents may save money.
“The completed project greatly reduces the amount of storm runoff flowing through the Sunrise Vistas development,” said Gremlich. “The reduction in storm flows has allowed for an application to FEMA to revise and reduce the mapped Special Flood Hazard Areas (SFHA). When the FEMA maps are revised almost all the SFHAs within the development will be gone and the requirement for the homeowners to have flood insurance will largely be gone, thus saving the residents a significant amount of money on their flood insurance premiums.”
When a project is completed, DEMA conducts a final inspection report. Anderson traveled to Mohave County to review the final work and write the report.
“We took pictures of the project. We looked at the final cost and compared it against what was awarded. We reviewed all the documentation that is needed for them to successfully go through audit,” said Anderson. “A report is put together, signed, and then sent off to audit.”
Anderson explained that the project is in audit, where all the reports and documentation is reviewed. Once everything has been satisfied, Mohave County will receive final payment.
The Sunrise Vistas project is another way in which DEMA and its local partners work together to improve the state and make communities safer for residents.
“DEMA was very helpful in obtaining the federal grant money and was helpful in navigating the paperwork and making the necessary inspections,” said Gremlich. “They were always available and helpful in answering questions and in making the process work.”