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Title:
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Request Authorization to Amend Intergovernmental Agreement with Flood Control District of Maricopa County for 27th Avenue and Olney Avenue Storm Drain Project (Ordinance S-45471)
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Title
Request Authorization to Amend Intergovernmental Agreement with Flood Control District of Maricopa County for 27th Avenue and Olney Avenue Storm Drain Project (Ordinance S-45471)
Description
Request to authorize the City Manager, or his designee, to amend Intergovernmental Agreement (IGA) with the Flood Control District of Maricopa County (FCDMC) for the 27th Avenue and Olney Avenue Storm Drain Project. Further request authorization for the City Treasurer to accept, and the City Controller to disburse, all funds related to this item. The request is to amend the original IGA for the City to undertake construction of the three drainage basins ahead of the proposed 72-inch storm drain. The estimated overall project cost is $6 million, of which $950,000 will include the construction of the three drainage basins. In addition, the City will operate and maintain the proposed three basins and the 72-inch storm drain when completed.
Report
Summary
In late 2015, the FCDMC, in partnership with the City, 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. Floodprone areas known as Areas of Mitigation Interest (AoMIs) were identified through the updated study. A total of 11 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, two project elements include three drainage basins and 72-inch diameter storm drain.
Due to the urgency of implementing a portion of this project earlier to prepare for the 2019 monsoon season, this request to amend the original IGA would be for the City to undertake construction of the three drainage basins ahead of the proposed 72-inch storm drain. The three drainage basins are on approximately five acres along 23rd Avenue north of Olney Avenue and along 22nd Avenue north of Olney Avenue. Currently through the executed IGA, the FCDMC is to perform the final design and implementation of the basins. With this amendment, the FCDMC would provide the City the project design for the City to lead the management of construction of the drainage basins. Also, through the existing IGA, the City is responsible for obtaining the required land for the basins. The estimated cost for constructing the drainage basins is $950,000. The project also included seeking a Federal Emergency Management Agency (FEMA) proposed Hazard Mitigation Assistance (HMA) grant for the drainage basins, which was withdrawn due to the urgency of completing the basins before the upcoming 2019 monsoon season. FEMA had not made a final decision prolonging the necessary project development requirements to implement the project before the 2019 monsoon season.
Financial Impact
The terms of the IGA between the City and the FCDMC includes a joint cost share for project development and implementation of the 27th Avenue and Olney Avenue 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 projects included in the IGA are the:
Durango Regional Conveyance Channel Project, which was previously approved by the City Council on Oct. 4, 2017.
South Phoenix/Laveen Drainage Projects.
Rawhide Wash Project.
The City's contribution of up to $3 million is available in the Street Transportation Department's five-year Capital Improvement Program budget.
Concurrence/Previous Council Action
The IGA was recommended for approval at the Transportation and Infrastructure Subcommittee meeting on Feb. 13, 2018, by a vote of 4-0 and City Council approved on March 7, 2018.
Location
The project is generally located north of Olney Avenue and along 23rd and 22nd avenues.
Council District: 8
Department
Responsible Department
This item is submitted by Deputy City Managers Karen Peters and Mario Paniagua, and the Street Transportation and Public Works departments.