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Windsor Woods Tide Gate

Stop the Tide, Save the Storage

July 31, 2020

Hampton Roads Adaptation Forum

2

Presenters

Michael Bumbaco III, PE City of Virginia Beach Stormwater

Nicole Dane, PE Michael Baker International

Curtis HickmanWetland Studies and Solutions Inc.

PROJECT AREA

3

AtlanticOcean

Chesapeake Bay

Oceana Naval Base

City ofVirginia

Beach Limits

Lynnhaven River

MountTrashmore

Park

PROJECTAREA

N

TownCenter

4

Total Project Area – 2,600 Acres (8,500 Parcels)Windsor Woods – 1,300 Acres (3,700 Parcels)

Princess Anne Plaza – 1,100 Acres (3,800 Parcels)The Lakes – 185 Acres (1,000 Parcels)

Total Assessed Value – $2B

Windsor WoodsPrincess Anne

Plaza

TheLakes

▪ Flooded Homes and Property Damage

▪ Flooded Roads

▪Access Limited for:

o Emergency First Responders

oCity Maintenance Crews

oResidents

▪Areas Isolated until Flooding recedes

5

The Problem = Flooding

▪ Infrastructure is ± 50 years old (Built in 1960’s)

▪Area is Fully-Developed

▪ Existing storm drains are inadequate or non-existent

▪ Lack of storage

▪ Elevations in the area are low and flat

▪ Frequency & severity of storms is increasing

▪Area is tidally influenced

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Why the Problem?

PROJECT AREA

Tidal Influence & Natural Drainage

Patterns7

PROJECTAREA

AtlanticOcean

Chesapeake Bay

N

City ofVirginia Beach

Limits

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Risk Assessment Map

Sewells Point Tide Gauge Data

24-Hour Precipitation Return PeriodNorfolk Airport Rain Gauge (NOAA/NWS)

Hurricane Matthew

▪ Rainfall from Hurricane Matthew (Oct 2016) resulted in extreme flooding

▪ 800 Residences Reported Damage (Modeling approximates over 1,400)

▪ Many streets were impassable

▪ Flood Insurance Rates have significantly increased

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Flooding from Hurricane Matthew (2016)

4412

Work Leading to the Tide Gate?

▪ Public Outreach and Involvement

▪ Windsor Woods Stormwater Management System Flood Mitigation Plan -CDM Smith - April 2018

▪ Final Windsor Woods Drainage Improvements PER –Michael Baker – September 2019

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Overall Solutions

▪Gates to Block Incoming Tide

▪ Stormwater Pump Stations

▪Additional Storage

▪ Flood Barriers

▪ Storm Drains

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Overall Preliminary Concept Plan(Recommended Infrastructure)

Lynnhaven P

kw

y

Lake

Windsor

Lake

Trashmore

Northgate Plaza

Ball Fields

POTENTIAL STORMWATER

STORAGE

NEW STORM DRAINS WILL BE

INSTALLED THROUGHOUTTHE PROJECT

AREA

POTENTIAL NORTH PUMP STATION,

TIDE GATE & BARRIER

LOCATION

WINDSOR WOODS PUMP STATION, TIDE GATE &

BARRIER LOCATION

POTENTIAL SOUTH TIDE GATE,

CHANNELS & BARRIER

LOCATION

Windsor Woods Tide Gate Project

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▪ Windsor Woods Tide Gate Selected by City to Move Forward

o Tide Gate (60 feet wide; 4 bays)o Pump Station (750 cfs)o Barriers (100-year)

Gate Blocks Incoming Tide Stormwater Storage

Windsor Woods

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Lake Trashmore

Natural Drainage Patterns

Windsor Woods

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Tidal Impacts

Lake Trashmore

Windsor Woods19

Proposed Pump

Station

Proposed Tide Gate

Lake Trashmore

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Proposed Barrier

Windsor Woods

Lake Trashmore

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Windsor Woods Tide Gate & Pump Station Site

Lake Windsor

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Windsor Woods Tide Gate & Pump Station Rendering

Lake Windsor

Windsor Woods Tide Gate Rendering

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Windsor Woods Tide Gate & Pump Station Rendering

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Windsor Woods Tide Gate & Pump Station Site

Lake Windsor

Lake Windsor

Lake Windsor

Mount TrashmoreSkatepark

Mount TrashmoreSkatepark

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Lake Windsor – Ex. Conditions (Low Tide)

Water Level at Low Tide

Thalia Creek

Lake Windsor

High Tide –

Low Tide –

UPSTREAMDOWNSTREAM

Available Storage Capacity at Low Tide

Natural Flow of Drainage

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Lake Windsor – Ex. Conditions (High Tide)

Water Level at Low Tide

Thalia Creek

Lake Windsor

Water Level at High TideHigh Tide –

Low Tide –

Tide Fills Available Storage

Incoming Tide

UPSTREAMDOWNSTREAM

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Lake Windsor – Ex. Conditions During Storm

Lake WindsorThalia

Creek

UPSTREAMDOWNSTREAM

Storage Capacity Exceeded Quickly and Flooding Occurs

Low Tide –

High Tide –

Water Level at Low Tide

Water Level at High Tide

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Lake Windsor – After Tide Gate Installation(Post-Improvements)

Water Level at Low Tide Lake

Windsor

Water Level at High Tide

Tide Gate in the Open Position

Normal Water LevelHigh Tide –

Low Tide –

UPSTREAMDOWNSTREAM

Thalia Creek

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Lake Windsor – After Tide Gate Installation(Post-Improvements)

Water Level at Low Tide

Lake Windsor

Tide Gate in the Closed Position

High Tide –

Thalia Creek

UPSTREAMDOWNSTREAM

Low Tide –

Storage Now Available Since Tidal Influence Eliminated

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Lake Windsor – After Gate & Pump Installed

Lake Windsor

Tide Gate and Pump Station In

Operation

High Tide –

UPSTREAMDOWNSTREAM

Pumps Used to Maintain Water

Levels Behind Gate

Additional Storage Created

by Pump Drawdown

Low Tide –

Thalia Creek

Regulatory

Pump Station

Storage(Water Quality)

Gates & Barriers

Storm Drain Network

Key Program Components

Regulatory Permitting

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▪ Permitting o Corps and DEQ Individual Permits

o Early Regulatory Coordination and Agency Involvemento Public Outreach and Buy Ino Alternatives Evaluation – Couldn’t Have Found a Better Site

▪ Aquatic Life o Frequency and Duration of Closureo Maintenance of Low Flow o Intake Structures – Entrainment

This is a Great Site for LEDPA!!!

34LEDPA – Least Environmentally Damaging Practicable Alternative

Fish Passage - Frequency and Duration of Closure

▪ Typically open during “Sunny Day” conditions

▪ Closed ~5-8 times a year

▪ ~24 to 48-hour pre-storm pump down

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Maintenance of Low Flow - Aquatic Life

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Intake Structures - Entrainment

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Intake Structures

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All Permits Received

▪ USACE and DEQ Individual Permits Issued

▪ No VMRC Permit Required

▪ A separate permit will be necessary for the larger pump.

▪ And the process starts again!

Future Permits

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Summary/Take-Aways

▪ Tide gate is the first project in this multi-faceted Long-term Program

▪ Permitting is Critical for Large Water Dependent Projects

▪ Regulatory Coordination needs to be Integral in Planning Process

▪ Public Involvement/Buy-In Important

▪ Pre-Storm Planning & Preparation is Critical

▪ Long-Term Operation & Maintenance Required

▪ Construction Anticipated Spring 2021

Thank You!

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