New Haven Land Trust Presentation

8/3/2019 New Haven Land Trust Presentation

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Pond Lily Dam RemovalPublic Meeting

PROJECT UPDATE

MILONE & MACBROOM

Pond Lily Dam Removal

PRESENTED BY:

Jeanine Armstrong Gouin, P.E., Vice PresidentJenn Hoyle, Water Resource Engineer

Milone & MacBroom, Inc.

Cheshire, Connecticut

January 30, 2012

Project Goals & Objectives

Restore River Habitat to a More Natural Condition Restore River Habitat to a More Natural Condition

Enable Anadromous and Resident Fish Passage

Provide Flood Relief

Mitigate Liability Associated with Dam Failure

Maintain and Enhance Habitat

Enable Anadromous and Resident Fish Passage

Provide Flood Relief

Mitigate Liability Associated with Dam Failure

Maintain and Enhance Habitat

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Promote Environmental Education & PassiveRecreation

Promote Environmental Education & PassiveRecreation


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Work Completed To Date

Project Kick-Off Meeting

Project Kick-Off Meeting

Field Survey and Base Mapping

On-Site Assessment: Spillway and Dam Inspection

Ecological Communities Identification

Sediment Probing and Sampling

Field Survey and Base Mapping

On-Site Assessment: Spillway and Dam Inspection

Ecological Communities Identification

Sediment Probing and Sampling

MILONE & MACBROOM


Hydraulic Assessment & Flood Analysis

Alternatives Analysis

Preliminary Design

Hydraulic Assessment & Flood Analysis


Preliminary Design

Pond Lily Dam

191-foot long spillway

Six-feet high

Stone Masonry

Construction with

Concrete Cap

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Spillway is in Poor

Condition


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West River

Watershed West River: 34.6 square

miles

Pond Lily: 16.6 square miles

(47% of West River

watershed)

32% developed, 50%

forested (5% increase in

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1985 and 2006)

18 river miles between

Bethany and West Haven

Harbor

Observed Wetlands

Vegetation cover types

native as well as non-

native and invasive plant

species

The ond is slowl fillin

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with sediment and

transitioning to wetland


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Observed Wildlife

Mammals

white tailed deer

eastern chi munk

Birds

Canada goose

mallard

common raccoon

Virginia opossum

gray squirrel

striped skunk

ground hog

American robin

woodpeckers

European starling

common grackle

red winged blackbird

house + song sparrows

Northern cardinal

black-capped chickadee

Retiles & Amphibians

painted turtle

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u e mouse

white-breasted nuthatch

American goldfinch

blue jay

snapp ng ur e

Eastern garter snake

American toad

northern water snake

Fishery Resources

bluegill

largemouth bass

brown bullhead

white sucker

American eel

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blueback herring American shad


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Sediment Types

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Sediment

Thickness

Sediment thickness ranges

rom ess an a oo o ve

feet, with the majority of

the pond in the range of

three to four feet of

accumulated sediment.

Approximately 7,500 cubic

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ar s o se ment n t eproposed channel.


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Dam Alternatives:

Do Nothing

Total Dam Removal (spillway and embankment)

Full Spillway Removal (full depth, full width)

Partial Spillway Removal (full depth, partial width)

Channel Restoration Alternatives:

Left Bank Alignment

Sediment Alternatives & Issues:

Do Nothing (allow natural erosion)

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Right Bank Alignment

Thalweg Alignment

Full Removal

Partial Removal, In-Situ Stabilization

On-Site vs. Off-Site Disposal Quality & Quantity Considerations

Alternative 4

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Preliminary Design Considerations

Dam Removal

Elimination of the long-term liability associated with

the dam

Appropriate management and long-term stability of

accumulated sediment

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Restoration of a whole riparian ecosystem, including

the stream corridor and floodplain


Sustainable Urban Greenway & Nature Preserve

Evergreen screenings

Native understory tree and shrub masses

The stream bank community

The floodplain community

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Scrub Shrub Wetland

Herbaceous Meadow with Large Fern Groves


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Public Interaction & Education

Create an environment that is conducive to site access

Embrace educational opportunities

Create a people-friendly environment

Plan for future site amenities, such as walking trails,

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,

areas

Create a safe environment

NEXT STEPS

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Preliminary Design: Channel Design

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The proposed channel is a low gradient single stem alluvial channel

with connectivity to a well-defined floodplain.

Preliminary Design: Flood Analysis

West River in the project

reach has a low slo e..

Under existing conditions,

dam is overtopped.

Removal of the spillway

will reduce upstream

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.

Little flood control relief

during major storm events.


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Preliminary Design: Fish Passage

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Design creates an easily passable reach that will allow the migrating

alewife and herring easy access to upstream ponds for spawning.

Current Project Status

Preliminary design completed. Preliminary design completed.

Grant applications for necessary funding in

progress.

Grant applications for necessary funding in

progress.

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Next Steps

1. Permitting New Haven City Plan Department

Dam Safety Permit (CT DEEP)

Water Diversion Permit (CT DEEP)

Flood Management Certification (CT DEEP)

401 Water Quality Certificate (CT DEEP)

Section 404 Permit (USACE)

2. Final Design & Construction Documents

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3. Contractor Selection4. Construction

New Haven Land Trust Presentation

Documents

Transcript of New Haven Land Trust Presentation