Slide 1

An Overview of the GWK Retention Treatment Facility and The August 11, 2014 Wet Weather Event

August 19, 2014

Slide 2

Overview Elements

1. Brief History of the GWK Drainage District and GWK

Retention Treatment Facility

2. Design

3. Operations

4. August 11, 2014 Wet Weather Event

5. Next Steps

GWK Drainage System

GWK System Map

GWK System Map: Clawson Vicinity

Towards GWK RTF

Slide 6

GWK RTF Design: Criteria

The GWK RTF is a Pollution Control Facility that

screens out sanitary trash and other solids and

provides disinfection using chlorine before

discharging to the Red Run Drain.

Chlorine contact time and wet weather volume

storage provided using the 124 Million Gallons of

storage capacity available in the facility.

Slide 7

GWK RTF Design: Criteria

Designed to address flows from a 10-year, 1-hour

design event. Peak flow rate into the GWK RTF ≈

3.1 Million Gallons per Minute (7,000 cfs).

GWK RTF construction and upgrades were required

to reduce Combined Sewage Overflows (CSOs) and

be in compliance with MDEQ rules and the Federal

Clean Water Act.

Slide 8

GWK RTF Design: Extent of Pollution Control Facility

Slide 9

GWK RTF Design: Original Influent Weir

Slide 10

GWK RTF Operations Explained: Operator’s Walk-through

Slide 11

August 11, 2014 Wet Weather Event: Event Statistics

WRC has a network of rain gauges that provide

rainfall depth from every wet weather event.

Rain Gauge 0880 is located at the GWK RTF and is

used to determine rainfall amounts for much of the

GWK RTF service area.

Slide 12

August 11, 2014 Wet Weather Event: Event Statistics

Rainfall frequency is determined by referencing

published texts.

At the time of the GWK RTF design “Technical Paper

40” was a reference text.

Today. “NOAA Atlas 14” is the reference text.

Slide 13

August 11, 2014 Wet Weather Event: Radar Rainfall

Slide 14

August 11, 2014 Wet Weather Event: Radar Rainfall

Slide 15

August 11, 2014 Wet Weather Event: Comparison to Design Event

10:0010:30

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0

0.1

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Design Event Recorded Rainfall

Rain

fall

Dept

h (in

ches

)

Slide 16

August 11, 2014 Wet Weather Event: Effect on GWKDD and RTF

August 11, 2014 Wet Weather Event: Effect on GWK RTF

Slide 18

August 11, 2014 Wet Weather Event: Effect on GWK RTF

August 11, 2014 Wet Weather Event: Effect on Red Run Drain

Red Run at GWK Outlet (Dequindre)

August 11, 2014 Wet Weather Event: Effect on Red Run Drain

Red Run at Mound Red Run at Van Dyke

Slide 21

August 11, 2014 Wet Weather Event: WRC Next Steps

Collect community data from basement flooding

Hydraulic study of the GWK facility

Slide 22

Oakland County Executive Office Announcement

“The flooding impacted thousands of individuals who now have many questions about how to recover from this disaster. The Multi-Agency Resource Center (MARCs) will be an opportunity to meet with experts who can answer some of those questions.”

– L. Brooks Patterson

The Southfield MARC will be open 11 a.m. – 7 p.m. Wednesday and Thursday at the Southfield Pavilion, 26000 Evergreen Road south of the I-696 expressway.