California Coastal Commission Permitting For Emergency

Response to the 2010 El Nino Storm Event

Departm

en

t of P

ub

lic Works

July 2011

Presentation / Overview

• Project Area and Vicinity

• History / Background

• Summarize the History of El Nino Storm Damage 1997 to 2010

• Illustrate Potential Impacts to the Lake Merced Tunnel

• Present Project Elements

• Key California Coastal Commission Concerns:• Alternative Analysis • Sand Supply• Sea Level Rise• Monitoring and Maintenance • Public Access and Recreation • Visual Resource • Long Term Planning Efforts

• Funding

Project Area and Vicinity

The project area is located along Ocean Beach and the Great Highway, from Sloat Boulevard to Skyline Boulevard

Project Area

History of Wastewater Facilities

In 1979, in response to the Clean Water Act to improve water quality, the City prepared and the Coastal Commission adopted the San Francisco Wastewater Public Works Plan to address combined sewer overflows.

Following the adoption of the plan, the following facilities were constructed to reduce combined sewer overflows from over 58 to 8 events per year:

• Westside Transport and Storage Structure

• Westside Pump Station

• Lake Merced Transport Tunnel

• Oceanside Treatment Plant and Southwest Ocean Outfall

Wastewater Facilities

West Side Pump Station

Lake Merced Transport Tunnel

West Side Transport Box

Southwest Ocean Outfall

Oceanside Treatment Plant

Summary of Ocean Beach Activities

• This section of coast (Point Lobos to Sloat Boulevard) has been a managed

system that was originally constructed in the early 1900s

• Integrally tied–in to large scale coastal processes in the vicinity

• Beach has experienced an erosional trend, resulting in several studies being conducted by the Corps and City since 1992

• Substantial resources have been spent in seeking solutions

• Significant stakeholder outreach has occurred over this time period

• Major infrastructure is at risk in certain locations, with disastrous consequences if not addressed

• City is seeking interim solution until long-term solution is developed/ funded/ implemented

Erosion Trend–Sloat Parking Lots 1992-2010

South Parking Lot

North Parking Lot

Erosion Trends

Reach 1 Reach 309/07/1995 0 006/23/1997 0 008/15/2000 20 20

08/2001 0 009/30/2002 0 010/26/2003 10 1001/31/2004 0 003/10/2005 0 006/30/2007 0 008/13/2009 0 004/14/2010 20 40

Total 50 feet 70 feet

Beach Elevation Trends

2010 Storm

The El Nino type storms during the winter of 2009/2010 were a result of 7 foot tides and 22 foot run up over an extended period of time along Ocean Beach.

Summary of 2010 El Nino Storm Damage

Reach 3

Reach 2

Reach 1

Potential Impacts to the Lake Merced Tunnel

• The loss of bluff during the El

Nino storm events is encroaching upon the Lake Merced Tunnel.

• Currently, there is 22 feet between the tunnel and the eroding toe of the bluff.

• Jacobs Associates, a consultant for the PUC identified the loss of side slope as a critical concern and recommended in-situ ground improvements to protect the tunnel from additional regression of the bluff slope.

Reach 1

Reach 1

Risk Analysis

A January 2010 type storm would result in 20 to 40-feet of bluff recession.

1.The probability that the Tunnel in Reach 3 would be threatened immediately (within 5 to 7 years) is over 80% without the pile wall. The probability of

roadway closure is over 95% over the same period.

•The probability that the Tunnel in Reach 1 would be threatened in the near future (within 5 to 7 years) is over 80% without the revetment in place.

•The probability that the Tunnel in Reach 2 would be threatened in the near future (within 5 to 7 years) is about 50%.

Reach 1Reach 1

Project Description

SFDPW is requesting to extend the authorization for the emergency revetments

(a) Permitting the constructed EQR that was in response to the 1997 El Nino event.

(b) Permitting and re-grading the 2010 emergency revetment to provide a well-defined transition at the southern end of Reach 1, prevent erosion further south, and reduce the need for additional rock to be imported.

1997 EQR

2010 Rock Revetment 2010 Rock Revetment

Project Description

(c) Permitting proposed pile walls at Reach 2 & 3 to protect the Tunnel from future storm damage.

(d) Permitting the Great Highway south of Sloat Boulevard that was realigned based on traffic counts, factor of safety, storm strengths, and storm reoccurrence analyses.

• Need for structural support to protect the Lake Merced tunnel• Rationale for the Great Highway southbound lane realignment.

Reach 2 Reach 3

Alternatives Analysis

Rea

ch 1

R

each

2

• Moving the southbound roadway east eliminates the immediate need for structural improvements at Reach 2 and other portions of the Great Highway excluding Reach 3.

• At Reach 3, alternatives such as pile walls, rock revetments, buried seawalls, and no-action were explored. Pile walls were selected because other alternatives would require construction on National Park Service property and additional permit approvals.

Rea

ch 3

Sand Supply

• With the primary source of sand originating from off-shore systems, the reduction of sand supply threatens the existing beach.

• Shoreline erosion along the bluffs is not sufficient to replenish beach sand and the geology of the bluffs does not contain an adequate supply of compatible sand to support the beach long term.

• Even with the abandonment of the southbound lanes and the allowance of bluffs to retreat, there is not enough land for a beach to establish itself in front of the Lake Merced Tunnel.

Sea Level Rise

• The structure generally can accommodate up to 3-4 feet of sea level rise,

after which the overtopping could be more frequent than once every 100 years.

• Example at Reach 1: The existing beach bluff will further be threatened by storm swells given sea level rise.

Revetment height

4 feet sea level rise

Run-up from 22 foot storm swells

during El Nino storms

Exi

stin

g 30

foo

t re

vetm

ent

Sea Level

Monitoring and Maintenance

• A Monitoring and Maintenance Plan will be developed to:

• Track the rate of shoreline erosion • Monitor performance of the structures• Establish triggers for management actions

•The Monitoring and Maintenance Plan will need be amended in response to adopted and implemented Beach Nourishment Plan and Ocean Beach Master Plan.

Public Access and Recreation

Establish and maintain existing beach access via sand ladder along Sloat Blvd.

Reposition existing rock in 2010 revetment to create a ramp for beach access

Provide a path along the original southbound traffic lanes for lateral access

In the Public Access Plan, there are several proposals to reestablish beach access.

1 2

3

2

3

1

Visual Resource

• The visual condition at Ocean Beach in the 3000 feet project area varies from rubble to naturally eroding bluffs.

• The 1997 EQR was constructed in an area lined with rubble.

• The 2010 revetment was designed to protect infrastructure and natural bluffs.

• The remaining 2000 feet of the project area is lined with rubble and other debris.

1997 EQR Rock, rubble and debris from retreating bluffs

Rock revetment in response to the 2010 El Nino storm event

Rubble and other debris along the project area from eroding bluffs

Long Term Planning Efforts

SFDPW continues to support collaborative long term planning processes in order to maintain the sustainability of the City’s infrastructure and to preserve wildlife habitats, beach access, and natural processes.

Current Long Term Planning Efforts • NPS – General Management Plan

• Draft EIS 08/2011 – 09/2011

• USACE & NPS – The Beach Nourishment Plan• Draft Report 10/2011• Draft EA 11/2011

• SPUR – The Ocean Beach Master Plan • Concept Plan 12/2011 – 01/2012

• SFPUC – Sewer System Improvement Program • Present – 2014

When implemented, these plans individually or collectively would serve as guiding documents to the future of Ocean Beach and Great Highway Corridor.

Funding

Year Purpose CCSF ($)

CA DBW Grants ($)

Federal Grant for USACE work ($)

1996 Revetment 500,0001999 Initial Sand Nourishment 350,0002000 Sand Nourishment 298,000 100,0002001 Sand Nourishment and Beach Post Monitoring 400,000

Reconnaissance Phase of Corps Project 100,000

Studies for Long Term Solutions 470,000 1,100,000

2002 Detour Southbound Lane 342,8592005 Ocean Surveys and USACE Labor for the

alternatives report200,000

2006 Completed near shore surveys and continuing to monitor the pilot study disposal site 200,000

2008 & 2009 Army Corps 933 Program Study 744,000

2010 & 2011 Revetment, Roadway Repairs, Drainage Corrections

2,500,000

Technical Studies 500,000TOTAL $5,360,859 $1,200,000 $1,244,000

To date, $7.8 million dollars has been spent to provide emergency response beach nourishment, study, and monitoring primarily south of Sloat.

Conclusions

• The permit request by the City is only the minimum structures that directly protect

its infrastructure related to the impact of the El Nino storm event, namely relocating the roadway where feasible, installing the two revetments, and identifying the need to install two pile walls.

• Over the past 15 years, the City’s responses to the area have been episodic as isolated El Nino type storms are triggering emergency responses. As the dynamic situation at Ocean Beach unfolds, the ability to address future El Nino type events depends on the ability of stakeholders and public agencies to determine and implement short and long term solutions in non emergency situations.

• Over the past 15 years, the City has funded sand nourishment projects, assisted the USACE in federal appropriations for long term planning, supported USGS ongoing studies and monitoring, prepared numerous monitoring reports, generated technical studies on risk analysis and alternatives, engaged stakeholder groups and supported the SPUR Master Plan effort.

Questions?