Public Meeting

Zone 7 Boardroom

February 13, 2018

Arroyo Mocho Medeiros

Parkway Project

1

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

2

Project Overview

Objective is to Discuss

–Flood Risk Reduction

–Sediment Management

–Planting

–Access and Site Use

AGENDA

3

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

4

Arroyo

Road

College Avenue

5

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

6

Best Opportunity to Comment (to aid in

meeting $500,000 grant deadline)

Opportunity to Comment at Zone 7 Board

Meeting(s)

7

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

8

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

9

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

10

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

12

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

13

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

15

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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