Arroyo Mocho Medeiros Parkway Project - Zone 7 WaterArea of high groundwater recharge potential...
Transcript of Arroyo Mocho Medeiros Parkway Project - Zone 7 WaterArea of high groundwater recharge potential...
Public Meeting
Zone 7 Boardroom
February 13, 2018
Arroyo Mocho Medeiros
Parkway Project
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Flood Control District for Eastern Alameda County
Water Wholesaler
– City of Livermore
– City of Pleasanton
– Dublin San Ramon Services District
– California Water Service Company
– Untreated water supplier to agricultural users
Groundwater Basin Manager
Not a Land Use Planner
ZONE 7 WATER AGENCY
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Project Overview
Objective is to Discuss
–Flood Risk Reduction
–Sediment Management
–Planting
–Access and Site Use
AGENDA
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MEDEIROS PARKWAY OPPORTUNITIES
SMMP Goals
Reduce flood risk through
effective flood control system
Ecologically-focused projects
Watershed-wide view –
downstream connectivity
(WQ, GW recharge, sediment
management, etc.)
Fiscally responsible
Corresponding opportunities at
Medeiros Parkway
Flood attenuation onsite to relieve flooding
downstream
Rare opportunity to preserve and enhance
alluvial woodland and riparian vegetation, and
aquatic habitat complexity
Area of high groundwater recharge potential
Improve water temperature - 303d listing
Chronic sedimentation at Holmes Street
bridge requiring periodic cleanout to maintain
capacity and reduce flood risk
Attractive for grant opportunities looking at
multi-benefit projects
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Arroyo
Road
College Avenue
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FLOOD ATTENUATION BASIN
LOWERED FLOODPLAIN
SEDIMENTATION ZONE
SEDIMENTATION ZONE
RAISED TRAIL
LOWERED TRAIL
SECONDARY CHANNELS
OAK WOODLAND WILLOW - COTTONWOOD
SYCAMORE ALLUVIAL WOODLAND
WILLOW – COTTONWOOD [existing]
CULVERT
MAIN CHANNEL [existing]
Arroyo
Road
College Avenue
Conceptual Plan
February 2018
Spring 2018
– Engineering Design effort
continues
– CEQA Public Draft
o 30-Day public review period
Summer 2018
– CEQA Final Document and
Certification
– Permitting
Fall 2018
– Final Engineering Design
Spring – Fall 2019
– Construction
ESTIMATED PROJECT TIMELINE
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Best Opportunity to Comment (to aid in
meeting $500,000 grant deadline)
Opportunity to Comment at Zone 7 Board
Meeting(s)
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PROPERTY RESPONSIBILITIES AND PARTNERSHIPS C
ity
of
Liv
erm
ore
•Recreation Planning
•Routine Trail Maintenance
•Vegetation Maintenance (trails)
Pu
blic S
afe
ty
•Fire Safety
•Homeless
•Public Safety
Zo
ne
7 W
ate
r A
ge
ncy
•Regional Flood Control
•Vegetation Maintenance (in-channel, habitat)
•Groundwater Management
Existing Flood Risk
– Downstream flooding at Stanley Blvd
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FLOOD RISK REDUCTION
February 1998, Stanley Blvd January 2017, Holmes St
Opportunity to reconnect floodplain
– Flood Attenuation Basin on north side of the bike trail
Detain high flows: 10- to 25-year storm
– Larger storm like the January 2017 storm would enter the basin
Standing water present for up to a few days
FLOOD RISK REDUCTION
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Arroyo
Road
College Avenue
FLOOD ATTENUATION BASIN
Excavation to increase basin
capacity
– Existing Capacity: ~27 acre ft
– Proposed Capacity: ~65 acre ft
– More Excavation = More Storage +
Higher Cost
– Fit Neighborhood Setting
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FLOOD ATTENUATION BASIN
2-3 ft
7-8 ft
3-4 ft
Estimated excavation depths
elevation 493’
100 yr flood elevation 485’
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Example of a 2:1 slope Example of a 3:1 slope
FLOOD ATTENUATION BASIN
Reduce accumulation at Holmes Street Bridge
SEDIMENT MANAGEMENT
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Does not eliminate need for sediment management at the
bridge
Encourages natural sediment accumulation in areas upstream
of bridge
Depressions along channel
Minimize area affected by sediment removal
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SEDIMENT MANAGEMENT
SEDIMENTATION ZONE
SEDIMENTATION ZONE
Arroyo
Road
College Avenue
Targeted Plant Communities
– Sycamore Alluvial Woodland Habitat
– Oak Woodland Habitat
– Willow/Cottonwood Habitat
Preserve mature native trees as much as feasible
– Sycamores and oak in flood attenuation basin
– Almond tree in flood attenuation basin
PLANTING PLAN
14 Oak woodland Willow-cottonwood Sycamore alluvial woodland
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PLANTING PLAN A
rroyo R
oad
College Avenue
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OAK WOODLAND WILLOW - COTTONWOOD
SYCAMORE ALLUVIAL WOODLAND
WILLOW – COTTONWOOD [existing]
Arroyo
Road
College Avenue
Promoting Native Species
Reducing/removing invasives
– Blackberry, tree of heaven, ivy/periwinkle
– All or select eucalyptus to be removed
o ~ 5-7 impeding work
o High fire hazard, propagate, allelopathic (inhibit growth of other plants)
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PLANTING PLAN
Target communities – more sparse, canopy results in less
brush, less weedy grass land
Consulted with Livermore-Pleasanton Fire Department
Maintenance Program
– Routine mowing
– Invasives removal
– Watering
– Limbing of dense willows
FIRE RISK
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Emergency Services
– Continued access for Police
and Fire
Recreation
– Same access points
– Continued access to all
areas
– Temporary closure during
construction
– City of Livermore continues
to maintain bike trail
ACCESS AND SITE USE
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Maintenance Work
– Trail Maintenance
– Vegetation Maintenance
– Sediment Removal
– Bank Repairs
Vehicular access at South S Street
o Gated or bollards
MAINTENANCE ACCESS
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