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Oct
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ANDREW SMITH, PE, CFM LAURIE BROWN
MCCLAY VALLEY DETENTION BASIN RETROFITS
AGENDA
Project Background
Water Quality in Detention Basins
Improvement Features
Proposed Project Improvements
Questions
2
PROJECT BACKGROUND
3
PR
OJE
CT
BA
CK
GR
OU
ND
PROJECT BACKGROUND
4
2012 Stormwater Masterplan •Basins Identified for Water Quality Retrofits •Black & Veatch team selected for improvement design
Meeting with trustees on May 20th Hydrologic and Hydraulic Investigations
WATER QUALITY IN DETENTION BASINS
5
WA
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R Q
UA
LIT
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N D
ET
EN
TIO
N B
AS
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WATER QUALITY
6
Methods of WQ Improvement
• Removal of Sediment
• Nutrient Uptake
• Detention of Small Events
• Filtering Overland Flow
IMPROVEMENT FEATURES
7
IMP
RO
VE
ME
NT
FE
AT
UR
ES
• Improved McClay Valley Outlet
• Debris screen to prevent clogging of the outlet
• Low flow outlet for small events
• Improved Francis Howell Outlet will provide Water Quality Improvement
• Debris Screen
• Plate with holes drains small events
• Overflow outlet for larger storms
MODIFIED OUTLET
8
IMP
RO
VE
ME
NT
FE
AT
UR
ES
• Provides Water Quality Improvement
• Prevents Sediment Accumulation in Basin
• Assists with Flood Control
• Prevents debris from clogging outlet
SEDIMENT FOREBAYS
9
Sediment Forebay Locations
IMP
RO
VE
ME
NT
FE
AT
UR
ES
• Native Plantings
• Provides Water Quality Improvement
• Habitat for Fish and Aquatic Species
SHORELINE TREATMENT
10
PROPOSED PROJECT IMPROVEMENTS
11
PR
OP
OS
ED
MC
CL
AY
VA
LL
EY
IM
PR
OV
EM
EN
TS
• Rebuild Spillway and Outlet
• Replace existing apron
• Provides WQ Storage
• Reduces downstream flows
• Re-shape/Revegetate Basin
• Replace Downstream Pipe with Open Channel
• Sediment Forebay
• Remains a Dry Detention Basin
FRANCIS HOWELL BASIN IMPROVEMENTS
12
PR
OP
OS
ED
MC
CL
AY
VA
LL
EY
IM
PR
OV
EM
EN
TS
• Modified Outlet
• Permanent Pool lowered to original 554 elevation
• Provides WQ Storage
• Reduces downstream flows
• Eliminate Overtopping
• Dredge Sediment
• Shoreline Treatments
• South Bank Stabilization
• Sediment Forebay
MCCLAY VALLEY BASIN IMPROVEMENTS
13
PR
OP
OS
ED
MC
CL
AY
VA
LL
EY
IM
PR
OV
EM
EN
TS
BASIN IMPROVEMENTS
14
EXISTING CONDITIONS
10/28/2013
16
PROPOSED ENHANCEMENTS
EXISTING CONDITIONS
26 December 2012 PowerPoint Sample
18
PROPOSED ENHANCEMENTS
QU
ES
TIO
NS
19
QUESTIONS
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