RESERVOIR SEDIMENT MANAGEMENT RESERVOIR SEDIMENT MANAGEMENT LOS - - PowerPoint PPT Presentation

RESERVOIR SEDIMENT MANAGEMENT

LOS ANGELES COUNTY FLOOD CONTROL DISTRICT

RESERVOIR SEDIMENT MANAGEMENT

LOS ANGELES COUNTY FLOOD CONTROL DISTRICT

Presented by: Sterling Klippel, PE

LA County Flood Control District

Owns and operates complex flood protection and water conservation system that includes:

• 14 major dams
• 162 debris basins
• 500 miles of open channel
• 27 spreading grounds facilities

Water Conservation

San Gabriel River Water Conservation System

Sediment Concerns

• Fires accelerate sediment

accumulation

• Reduced reservoir capacity
• Potential to block outlet works
• Increased flood risk to

facilities/communities downstream

• Creates increased risk for dam

safety

Image Credit: NASA

RESERVOIR SEDIMENT MANAGEMENT PROJECTS RESERVOIR SEDIMENT MANAGEMENT PROJECTS

Devil’s Gate Dam and Reservoir

Watershed Size: 31.9 sq. mi. Percent Burned: 68% (100% undev.) Original Capacity: 3.7 MCY Remaining Capacity: 1.3 MCY Planned Sediment Removal: 1.7 MCY Construction Period: 2018 – 2023

Image Credit: Arroyo Seco Foundation

Cogswell Dam and Reservoir

Watershed Size: 39.2 sq. mi. Percent Burned: 90% Original Capacity: 19.8 MCY Remaining Capacity: 16.8 MCY Planned Sediment Removal: 2.6 MCY Construction Period: 2018 – 2020

Big Tujunga Dam and Reservoir

Watershed Size: 82.3 sq. mi. Percent Burned: 87% Original Capacity: 10.1 MCY Remaining Capacity: 8.0 MCY Planned Sediment Removal: 2.0 - 4.4 MCY Construction Period: 2019 – 2023

Pacoima Dam and Reservoir

Watershed Size: 28.2 sq. mi. Percent Burned: 96% Original Capacity: 9.8 MCY Remaining Capacity: 4.3 MCY Planned Sediment Removal: 3.0 - 5.2 MCY Construction Period: 2020 – 2024

San Gabriel Dam and Reservoir

Watershed Size: 202.7 sq. mi. Percent Burned: N/A Original Capacity: 86 MCY Remaining Capacity: 71 MCY Planned Sediment Removal: 5 MCY Construction Period: 2019 – 2024

A SUSTAINABLE DEVIL’S GATE A SUSTAINABLE DEVIL’S GATE

A Sustainable Devil’s Gate

Following extensive community outreach and involvement, the Board approved the Devil’s Gate Reservoir Sediment Removal and Management Project. Protecting Communities Community‐Based Solutions Enhancing Native Habitat and Recreation

Protecting Communities

• The Station Fire caused 1.3 MCY
• f additional sediment to enter

Devil’s Gate Reservoir.

• Reservoir does not have

adequate capacity for a major storm event.

• Until sediment is removed,

there is significantly increased flood risk to 650 parcels and 447 structures along the Arroyo Seco.

Project Overview

Restores flood protection capacity and reduces flood risk

• 1.7 MCY project maximum
• 800,000 CY annual maximum

Establishes a permanent maintenance area for annual sediment removal

• Reduces need for major sediment

removal project in the future

Community‐Based Solutions

Since 2010, the Flood Control District has been listening and working with cities and community groups on efforts to address their concerns regarding the Project. As a result of these efforts, the project has been significantly enhanced:

Low emission trucks that meet EPA standards Access to trails during non- work hours and weekends with new wayfinding signage No truck traffic or staging on residential streets 70+ acres of enhanced

• pen space with native

vegetation

Enhancing Native Habitat and Recreation

Objectives

• Enhance recreational opportunities throughout Hahamongna Watershed Park.
• Restore habitat to attract a wide diversity of wildlife.
• Create high quality nesting habitat for least Bell’s vireos and southwestern willow

flycatchers.

• Provide a more pleasing experience for birdwatchers, hikers, equestrians, and

those that want to connect with nature.

Enhancing Native Habitat and Recreation

Enhancing Native Habitat and Recreation

Enhancing Native Habitat and Recreation

Thank You

Sterling Klippel, PE Principal Civil Engineer Stormwater Engineering Division