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Stormwater: A New Environment

A New Strategy

Overview

• Norfolk leading in developing adaptation strategies

• Current infrastructure conditions

• New normal—rainfall conditions are changing

• Adaptation approach

• Prioritization discussion

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Government Funding Focus

• Federal Government• Coastal & river flood risk reduction

• US Army Corps of Engineers assists local gov’t to fund floodwalls, berms, etc.• Requires 35% local match

• Commonwealth of Virginia• Stormwater

• No-interest loans and small grant program to improve water quality and control water quantity

• Local Government• Stormwater quality and quantity management

• Coastal flood management

3

Norfolk Leadership: Innovation in Action

Dutch Dialogues VIRGINIA

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Overdue for an Upgrade

• Design Standard➢ 10 year rain event—5.5

inches of rainfall within a 24 hour period

• Current System Capacity➢ 2 year rain event—3.5 inches

of rainfall within a 24 hour period

Current Stormwater System

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Rainfall Exceeding 2-year Rain Event

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The New Normal

• Heavy rainfall events are increasing

• Potential 20% increase in design standard➢Today’s 10yr is tomorrow’s 6yr

event

• More than 50% of rainfall events occur during elevated tidal events➢Making it difficult to clear the

systemP. Pomerenk Dec. 2016, Trends in Rainfall…

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Ground Conditions

PercentImpervious

Surface

• The yellow, orangeand red areas are mostly paved or hard—causing more water to run off more quickly

Current Conditions

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Citywide Trunk-line Capacity & Condition Analysis

Low PriorityMedium PriorityHigh Priority

Current Conditions

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Constrained Under Ground

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Storage Zone

Infiltration Zone

Green Infrastructure Best Practices Zones

Current Conditions

• Purple areas show where water can move into the ground using raingardens, pervious pavers, etc.

• Green areas show where the water table is high so that water will sit on top rather than move into the ground.

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Resilient Layered Strategy

Goal is to hold as much rain as close to where it falls as possible

• Retain

• Absorb

• Clean

• Release

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New Stormwater Retention Strategy• Increase underground capacity

• Pipes to increase flow and storage

• Cisterns

• Increase above ground capacity• Ponds/Wetlands

• Restored Creeks

• Bioswales

• Rain Gardens/Corner bumpouts

• Pervious Pavement

• Cisterns

• Rain barrels

• Increase system clearing ability• Pumps and force mains

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City Council Policy & Citizen Engagement Leading the Way

• Green Infrastructure Plan

• New Zoning Code

• Stormwater Fee Reduction program

• Vision 2100

• Retain Your Rain grants

• Adopt a drain program

• WAZE Connected Citizens Program

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Prioritization of Stormwater Projects

Current Methodology• Problem areas

• Capacity of existing systems

• Existing infrastructure

• Location of recently completed CIP or large projects

• Private property values

• Infrastructure conditions

• Classification of road

• Critical city infrastructure

• Economic development focus area

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Combined FY 2019 Operating and CIP Budget

Capital Projects$8,600,000

Infrastructure O&M$5,284,354

Debt Service$3,727,006

Street Sweeping$2,082,128

Engineering Program$1,883,541

Administrative Costs$1,330,571

Environmental Program$955,494

36%

4%

6%

22%

16%

9%

8%

Total FY 2019 Investment

$23.9 Million

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Council Discussion

What keeps Norfolk viable?

• Resident Concerns• Keep our houses from flooding

• Keep mobility

• Reduce neighborhood flooding

• City Prioritization?• Keep critical transportation networks clear

• Transformational projects

• Coordinate invest with large infrastructure projects

St. Paul’s Area Transformation

Ohio Creek: Upgrading existing systems

Fairmount Park

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New Revenue Investments

• $5M • 2 neighborhoods – master plan, trunk lines, 2 phases of construction

• St. Paul’s design & construction

• Upgrade equipment, operations and maintenance

• $10M• 4 neighborhoods - master plan, trunk lines, 3 phases of neighborhood construction

• St. Paul’s design & construction

• Upgrade equipment, operations and maintenance

• $15M• 4 neighborhoods - master plan, trunk lines, 4 phases of neighborhood construction

• St. Paul’s design & construction

• Add check valves to outfalls

• Upgrade equipment, operations and maintenance

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