Projects

Project Name: San Tan West Area Drainage Master Study (ADMS)

44

Project Manager:
Contact by phone at (602) 506-5469 or by email

Project is in Supervisor District:

• District 1: True
• District 2: False
• District 3: False
• District 4: False
• District 5: False

You can find your Supervisor District by clicking here.

Project Type: Study

Project Description:

The San Tan West Area Drainage Master Study (ADMS) officially started June 20, 2012 and was completed in November 2013. The boundary of the study area is the East Maricopa Floodway on the west, Sonoqui Wash on the north and east, and Hunt Highway on the south. The study area included the contributing watershed in Pinal County. The focus of the study is to collect and compile information on drainage and flooding problems, develop a detailed existing conditions hydrology (water flow) model using an advanced computer modeling technique called FLO-2D, and to prepare a flood hazard assessment for the area. The data collection and geomorphic (landform) assessment efforts are nearing completion, and the hydrology modeling work is underway.

The upper watershed south of Hunt Highway is mostly undeveloped but there are some low-density residential developments located in the mile strip on the south side of the highway east of Power Road. The north/south roadways in these developments become the primary routes for flood flows during storm events. Runoff east of Power Road is channeled through and around a new development into retention basins along the south side of Hunt Highway. Storm flows in this area overtop Hunt Highway and create flooding problems along and north of Hunt Highway. At Power Road, there is an existing 17-lot subdivision to the west on Gila River Indian Community land south of Hunt Highway. An old existing dike running parallel to Hunt Highway south of this development was put in place by farmers many years ago to protect farmlands north of Hunt Highway. The dike is not an engineered structure, and historical information indicates that it was maintained by the farmers at one time, but maintenance has lapsed as more farmers sell their land to residential developers.

North of Hunt Highway, land ranges from a few farms and orchards to low-density residential to new subdivisions. In the less developed areas, runoff is primarily sheet flow (runoff with a shallow depth over a broad area) to local natural washes. The natural washes in this area also vary from well-maintained to completely blocked. There appear to be significant drainage issues in the majority of the watershed. There is no consistent plan to accommodate runoff, and large volumes of sedimentation (accumulations of dirt and debris) are evident in all areas of older development. The Queen Creek area experiences local drainage problems with even minor storms. Most of the culverts at Hunt Highway are clogged. After a runoff event, sediment removal along the roadway shoulders throughout the watershed requires substantial effort. Sediment along the shoulders confines subsequent runoff to the streets, further compounding flooding and maintenance issues.

This completed project sets the stage for development of flooding mitigation projects that can be incorporated directly into Capital Improvement Programs of the primary stakeholders, including the Flood Control District of Maricopa County, Queen Creek, Gilbert, Pinal County.

Last Updated: 2/23/2021 1:11:46 PM