Upper Malletts Creek

Stormwater Conveyance Study

Project UpdateSeptember 30, 2013

Items to Review and Discuss• Alternatives

▫ Review alternative selection process

▫ Present modeling results and recommendations

• Discussion

• Next step – Final Report and City Council Presentation

Meeting Purpose• Discussion of project recommendations

• Gather public feedback

Project Goals• Reduce probability of flooding by improving

stormwater management

• Identify cost of implementation per level of service

• Do not adversely impact downstream interests

• Maintain and/or enhance water quality

• Long term sustainability

Available Information

• Website

▫ Online at www.uppermallettsstudy.org

• Online Flood Reporting Tool

Original Alternatives

Alternative Development

Alternative Packages

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Lawton Park High High X X X X X

Eisenhower Park High Medium X X X X X

Lans Basin Medium High X X X X

Pioneer HS (W of 7th) Low Low X

Pioneer HS (E of 7th) Low Low X X X

Cardinal Homes Low Medium X X X

Las Vegas Low Low X X X

Areas Outside of City Boundary 1 2 3 4 5 6 7

Ice Cube Medium Low X

Meadowinds Basin Low Low X

Flooding Map – March 15, 2012

Eisenhower/Churchill Park

Drainage Area

Initial Volume (cu. ft) 425,000Conceptual Volume 390,000Surface Area (acres) 1.9Anticipated Costs $1,250,000

Flooding Map – Post Eisenhower

Pioneer/Scio Church Improvements

Drainage Area Initial Volume (cu. ft) 80,000Conceptual Volume 400,000Surface Area (acres) 2.8Anticipated Costs $1,000,000

Flooding Map – Post Pioneer

Lawton Park

Drainage Area

Initial Volume (cu. ft) 825,000Conceptual Volume 340,000Surface Area (acres) 1.4Anticipated Costs $4,500,000

Flooding Map – Post Lawton

LocationOriginal Est.

VolumeConceptual

Volume

Lawton Park825,000 340,000

Eisenhower Park425,000 390,000

Pioneer (E. of 7th)80,000 400,000

Total 1,330,000 1,130,000

Volume Comparison

Footing drain analysis

Footing Drain Flow as PercentageOf Overall System Flow

94.2%

5.8%

• Measured flow approximately 5 gallons per minute

• Study using conservative flow of 10 gpm

• Total system flow is 483 cubic feet per second

• Total footing drain flow is 28 cfs

Footing drain analysis

Footing Drain Flow as PercentageOf Eisenhower Basin Flow

Footing Drain Flow as PercentageOf Lawton Basin Flow

2.2%

97.8%

5.4%

94.6%

No flow attributed to Pioneer basin due to drainage area specifics

Discussion

Next Steps

• Prepare report

• Presentation to Ann Arbor City Council

Gather Information

Public Engagement

Upper Malletts Creek Stormwater Conveyance Study TimelineP

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Preliminary Alternatives Analysis &

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Draft Study

Report

Final Study Report

Finalized Alternatives Analysis &

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Data Collection, Monitorin

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Upper Malletts Creek

Stormwater Conveyance Study

Project UpdateSeptember 30, 2013