Title
Intergovernmental Agreement with Flood Control District of Maricopa County for 51st Avenue and Dobbins Road Storm Drain Project (Ordinance S-48077)
Description
Request authorization for the City Manager, or his designee, to enter into an Intergovernmental Agreement with the Flood Control District of Maricopa County for the 51st Avenue and Dobbins Road Storm Drain Project. The design phase will include final design, rights-of-way acquisition, temporary construction easements, and utility relocations. Further request to authorize the City Treasurer to accept, and the City Controller to disburse, all funds related to this item. The estimated project cost for the design phase is $3.5 million of which the City's cost share is estimated to be $1.75 million.
Report
Summary
In late 2015, the Flood Control District of Maricopa County (FCDMC), in partnership with the City of Phoenix, initiated a study to update the Laveen Area Drainage Master Plan for the South Phoenix/Laveen area using new mapping and comprehensive flood model software. The updated study used data gathered from heavy rains and flooding that occurred in August and September of 2014. The study included analysis of existing regional drainage improvements such as detention basins, channels, storm drains and culverts, much of which had been constructed based on recommendations from earlier versions of the regional drainage master plans. Construction efforts prior to this study focused mainly on the downstream portion of the overall recommended regional system to provide an outfall for future improvements closer to the foothills. The study recommends additional regional drainage facilities extending further up into the watershed area to address neighborhood flooding issues that became more apparent during the 2014 storms.
The regional rainfall-runoff model now covers the entire study area. The new model identifies sources of stormwater flows so mitigation alternatives can be developed. Flood prone areas known as Areas of Mitigation Interest (AoMIs) were identified through the updated study. A total of five potential mitigation alternatives were developed and presented at two public meetings held in May of 2017, at which time, comments were received from attendees. After further technical analysis of potential mitigation alternatives, the following alternative component is proposed as one of the recommended drainage master plans for the study area.
Financial Impact
The estimated cost for this design phase is $3.5 million, which includes final design, rights-of-way acquisition, temporary construction easements, and utility relocations. The terms of the Intergovernmental Agreement between the City and the FCDMC will jointly cost share for project development of the 51st Avenue and Dobbins Road Storm Drain Project. The cost-share distribution between the City of Phoenix and FCDMC will maintain an overall 50/50 cost share, which is the standard cost- share allocation for projects funded by FCDMC. The City's contribution for the design phase of this project will be up to $1.75 million dollars and is available in the City's five-year Capital Improvement Program (CIP) budget.
Location
The project is generally located along 51st Avenue, between Dobbins Road and Sunrise Drive extending towards Olney Avenue the existing South Mountain Freeway Drainage Basin.
Council Districts: 7 and 8
Department
Responsible Department
This item is submitted by Deputy City Managers Mario Paniagua and Karen Peters, and the Street Transportation and Public Works departments.