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    7. 7.    
Regular City Council Meeting
Meeting Date: 12/03/2019  

Agenda Item
Resolution - Engineering: Consider a resolution authorizing the Mayor to execute Amendment No. 5 to Professional Services Contract No. 12113, with Halff Associates, Inc., for the Stormwater Master Plan.
Item Summary

This amendment increases the budget and extends time for continuing efforts in the professional services contract for Phase 2 of the awarded contract to Halff Associates, Inc., by the City Council on April 9, 2015.  This amendment continues efforts of capturing data for the entire City, including newly annexed areas within the Master Drainage Plan (MDP) model. This effort provides information to both the Development Services Engineering Department and the development community to make informed decisions about newly platted subdivisions in regard to drainage within the City limits. This amendment also includes a design for over excavation of Higinbotham Park to allow for better retention within the park and better drainage within the neighborhood.  Lastly, this amendment will provide for a feasibility study of Northwest Lubbock. This area specifically encompasses the Clovis Highway and Quaker Avenue region to determine potential ways of handling the storm water flows.

This Master Plan will provide a roadmap for the future regarding development practices, modeling techniques, drainage reviews, and capital project prioritization. The purpose is to provide information on potential solutions and cost estimates to aid City staff in managing ongoing development and to address localized drainage issues. The project is intended to provide the City with a tool to identify and prioritize potential drainage and flooding problems, and to develop proactive solutions for effective and efficient stormwater management. This plan is being integrated with the City’s GIS platform in order to provide a more efficient review of new localized drainage analyses and reduce the amount of staff time required to research, evaluate, and respond to new inquiries.

History - Stormwater Master Plan Phases 1 & 2 completed the following major milestone tasks:

The following are minimum tasks developed from Phase 2 (or continued from Phase 1) of the Stormwater Master Plan. This is not necessarily a comprehensive scope of work, but a summary of major tasks associated with this effort.

1. Drainage Criteria Manual (DCM) Ordinance Update
        • Updates of the new DCM have been completed and will be moving forward with a larger ordinance update in the future with the Unified Development Code (UDC). Minor revisions were approved by City Council on Decmber 3, 2019.
        • Finalize changes as needed to the ordinances in support of Stakeholder recommended changes to the DCM.

2. Stormwater Studies for Capital Projects
        • Refine overland and playa flood hazards utilizing detailed 2D modeling to identify Capital Improvement Projects for future fully developed conditions of the watershed.
        • Provided conceptual alternatives for future thoroughfare crossing locations and stormwater infrastructure sizing. Conceptual estimates of probable cost will be developed for flood mitigation alternatives and future planning.

3. Master Drainage Plan (MDP) Updates
          • Implemented updates to the methodologies identified during the pilot study for the Master Drainage Plan.
          • Prioritized Playa Systems for update based on current and predicted growth.
          • Developed MDP Mapping for use by the development community and other stakeholders, to develop inundation areas and expected flowpaths of the stormwater runoff.

4. GIS Application and Data Completion and Delivery
          • Drainage Analysis Review Tracking Application
          • Stormwater Project Tracking Application
          • Model Inventory GIS Database
          • Stormwater Master Plan GIS Data Delivery

The City of Lubbock has not previously had an overall Stormwater Master Plan that encompassed all aspects of drainage criteria and future planning. This master plan will update and is intended to build upon the previously completed Master Drainage Plan Update (last updated 2009-10), Drainage Criteria Manual (last updated 1997), and other studies, and to provide a holistic look at the City’s drainage issues. 

The intent is to ensure that future development practices prevent or reduce the need for another major storm sewer project, but the evaluation is necessary to make any needed modifications to the City’s current standards. As City growth continues and technologies continue to evolve, staff needs to have the proper tools and criteria to guide decisions well into the future. 

Fiscal Impact

Funding is appropriated for this purpose in Capital Improvement Project (CIP) 8595 Storm Water Master Plan - $250,000, CIP 8638 Canyon and Playa Lake Restoration and Restudy - $114,900, and CIP 92655 North Quaker and Clovis Drainage Project - $247,400, for a total of $612,300.

Staff/Board Recommending
Jesica McEachern, Assistant City Manager

Contract Backup
Budget Detail
CIP Detail

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