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8/3/2019 New Haven Land Trust Presentation
1/11
1/30/20
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
MILONE & MACBROOM
Pond Lily Dam Removal
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
Pond Lily Dam Removal
Hydraulic Assessment & Flood Analysis
Alternatives Analysis
Preliminary Design
Hydraulic Assessment & Flood Analysis
Alternatives Analysis
Preliminary Design
Pond Lily Dam
191-foot long spillway
Six-feet high
Stone Masonry
Construction with
Concrete Cap
MILONE & MACBROOM
Pond Lily Dam Removal
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
MILONE & MACBROOM
Pond Lily Dam Removal
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
MILONE & MACBROOM
Pond Lily Dam Removal
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
MILONE & MACBROOM
Pond Lily Dam Removal
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
MILONE & MACBROOM
Pond Lily Dam Removal
blueback herring American shad
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Sediment Types
MILONE & MACBROOM
Pond Lily Dam Removal
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
MILONE & MACBROOM
Pond Lily Dam Removal
ar s o se ment n t eproposed channel.
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Alternatives Analysis
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)
MILONE & MACBROOM
Pond Lily Dam Removal
Right Bank Alignment
Thalweg Alignment
Full Removal
Partial Removal, In-Situ Stabilization
On-Site vs. Off-Site Disposal Quality & Quantity Considerations
Alternative 4
MILONE & MACBROOM
Pond Lily Dam Removal
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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
MILONE & MACBROOM
Pond Lily Dam Removal
Restoration of a whole riparian ecosystem, including
the stream corridor and floodplain
Preliminary Design Considerations
Sustainable Urban Greenway & Nature Preserve
Evergreen screenings
Native understory tree and shrub masses
The stream bank community
The floodplain community
MILONE & MACBROOM
Pond Lily Dam Removal
Scrub Shrub Wetland
Herbaceous Meadow with Large Fern Groves
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Preliminary Design Considerations
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,
MILONE & MACBROOM
Pond Lily Dam Removal
,
areas
Create a safe environment
NEXT STEPS
MILONE & MACBROOM
Pond Lily Dam Removal
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Preliminary Design: Channel Design
MILONE & MACBROOM
Pond Lily Dam Removal
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
MILONE & MACBROOM
Pond Lily Dam Removal
.
Little flood control relief
during major storm events.
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Preliminary Design: Fish Passage
MILONE & MACBROOM
Pond Lily Dam Removal
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.
MILONE & MACBROOM
Pond Lily Dam Removal
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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
MILONE & MACBROOM
Pond Lily Dam Removal
3. Contractor Selection4. Construction