HomeMy WebLinkAboutCouncil Presentation 3-12-2019 NW Drainage StudyNorthwest Marana Drainage StudyKeith Brann, Town EngineerMarch 12, 2019
Purpose & Goals•FY19 CIP project•Detailed hydraulic study of NW Marana–Better existing conditions data–Better understanding of flow patterns•Verify effectiveness of contemplated major infrastructure•Determine if there are minor but effective projects
Phase 1 – Existing Conditions•Early FY19 – Data gathering–Review history of drainage problems–Verify existing drainage infrastructure–Pick up surveys of key infrastructure–Review newer local drainage studies•1stHalf FY19 – Building computer models–“East” model starts with 2009 FEMA mapping model–Modified for non‐regional storm event–20ft Grid west of CAP canal and north of Moore Road–New “West” model–Non‐regional storm event–20 ft Grid north of Twin Peaks RoadStudy Area
Original results from 2009 Tortolita Alluvial Fan Study
Northwest Marana Drainage - East side
Northwest Marana Drainage - West side
48 Hour time lapse
Phase 2 – Alternatives analysis•Review and model major flood control infrastructure previously contemplated–Barnett Channel–Marana Road Channel–Hardin Road Channel–Pinal County Line Channel•Model CAP canal near airport for breach scenario/potential LOMR•Review and model minor problem areas as directed, Possible areas include:–Marana Main street–Various dip crossings–Veteran’s cemetery area
Barnett Channel – modeled as previously designedNo significant improvement in regional flooding
Barnett Channel – With CAP interceptionSignificant Regional ImprovementsFloodplain reduced to Kirby Hughes Road
Marana ChannelNo significant improvement in regional floodingSignificant benefit to localized flooding
Hardin ChannelSignificant Regional ImprovementsFloodplain reduced north of Hardin Road
Marana Airport – Without embankmentsCAP & Twin Peaks Rd Embankments removed from model
Marana Airport – Breach Scenario 1Twin Peaks Rd embankment in placeCAP embankment modeled with 100ft breach
Marana Airport – Breach Scenario 2Twin Peaks Rd & CAP embankments modeled with 100ft breach
Next Steps•Incorporate stakeholder input•Complete drainage model runs•Prepare 15% DCR level designs and cost estimates for certain projects•Finalize master study findings•Identify potential benefit areas•Explore funding alternatives•Supplemental Services to be considered–Detailed design–Letter of Map Revisons