Presentation Program OutlinePresentation Program Outline

BACKGROUND / TMDLBACKGROUND / TMDL

WATERSHED CHARACTERISTICS

EROSION HISTORY

PLANNING PROCESS

ALTERNATIVE FORMULATION

BENEFITS - WATER SUPPLY / QUALITY / HABITAT

Background &Watershed TMDLBackground &Watershed TMDLBackground & Watershed TMDLBackground & Watershed TMDL

San Diego Creek / Newport Bay WatershedSan Diego Creek / Newport Bay Watershed

• Located within Orange gCounty, CA– 11 cities + County

• 154 total square miles• 154 total square miles– 118 square miles – SDC watershed

• Three main geographical areas

• Watershed drains into Newport BayNewport Bay

Borrego Canyon WashBorrego Canyon Wash

Sam Diego Creek 

Watershed

Borrego Canyon Wash

Newport Bay

•• Upper Newport Upper Newport BayBayBayBay– State Ecological Reserve

– Habitat for 200+ species of birds includingU B birds, including endangered light‐footed clapper rail & CA least tern

Upper Bay

•• Lower Newport Lower Newport BayBay

Lower Bay– Fully developed and 

channeled harbor

– One of largest small craft 

Lower Bay

pleasure harbors in the United States

Newport Bay and WatershedNewport Bay and Watershed

• Area has experienced dramatic change in land use since 1900

• Agriculture predominant

1947

Agriculture predominant use historically

1983 - 22%2002 5%

20072002 - 5%

• Rapidly urbanizing1983 - 47% urban 2002 - 75% urban

History of Sedimentation Problem

• Changes in land use of area

• Ditch drainages artificially channeledartificially channeled into Upper Newport Bay

Upper Newport Bay

SedimSediment Plume

History of Sedimentation ProblemHistory of Sedimentation Problem

• San Diego Creek 1967

channeled to UNB in 1965

• Major Floods in 1969• Major Floods in 1969 and 1978

• Large amounts of 1975

sediment deposited in Upper Newport Bay

• Ecological Reserve• Ecological Reserve adversely affected

1978

History of Sedimentation ProblemHistory of Sedimentation Problem

Upper Newport BayUpper Newport Bay

Sediment Plume

Early Efforts Early Efforts –– CWA Section 208 PlanCWA Section 208 Plan

• Local agencies sponsored intensive study to address excess di i N Bsediment in Newport Bay

• San Diego Creek Comprehensive Stormwater Sedimentation Control Plan completed in 1983

• Study indicated that bulk of sediment coming from surrounding hills, agriculture, 

d t tiand construction

• Executive Committee formed to continue to implement recommendations of the Plan

Early Efforts Early Efforts –– 208 Plan208 Plan

Consisted of land management practices to reduce sediment at its sources, and structural measures to localize sediment ,deposition and facilitate its management

• Agricultural BMPs• Construction BMPs• Installation of foothill basins• Installation of in‐channel basinsInstallation of in channel basins• Installation of in‐Bay basins• Stabilization of channels w/in developing areas

S di t M it i• Sediment Monitoring

Watershed Sediment BasinsWatershed Sediment Basins

Foothill Basins

In channelIn-channel Basins

In bayUnit I/IIIUnit II In-bay BasinsUnit I

Unit II

Unit I/IIIUnit II

Regulatory Background

• Newport Bay placed on 1996 303(d) list p y p ( )

HIGH priority for TMDL development

• Consent decree entered into October 31• Consent decree entered into October 31, 1997 between USEPA and Defend the Bay

• EPA promulgated TMDL on April 13, 1998 

• March 1999 – State of CA ratified the Sediment TMDL 

Sediment TMDL Targets

• 50% reduction in sediment load to Newport pBay within 10 years (2009)

• No greater than 1% change in Bay habitatNo greater than 1% change in Bay habitat acreages due to sediment deposition

• Depth requirements ( 7 ft MSL) in UNB basins• Depth requirements (‐7 ft MSL) in UNB basins

• Reduced frequency of dredging in UNB

Watershed Monitoring

• 8 streamgaging/sediment i i imonitoring stations

• Based on land‐use– Open spaceOpen space

– Agriculture

– Construction

– Urban

– Mixed

Fluvial Sediment Monitoring

Bay Monitoring

• Topographic/Bathymetric p g p / yand Vegetative Monitoring

– Every 3 years

• Sediment sampling

– Bed, suspended

Sediment Discharge 1983‐2008San Diego Creek at Campus Dr.

700 40

500

600

ands

of t

ons)

25

30

35

es)

TMDL 10-YR TARGET62,500 tons/yr

TMDL running average45 200 tons/yr

300

400

char

ge (T

hous

a

15

20

25

Rai

nfal

l (In

che45,200 tons/yr

100

200

Sedi

men

t Dis

5

10

15

01983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

0

5

Daily Max Annual Load - daily max Rainfall TMDL TargetDaily Max Annual Load - daily max Rainfall TMDL Target

Project Objective & ApproachProject Objective & ApproachProject Objective & ApproachProject Objective & Approach

Project Need Project Need –– Sediment ReductionSediment Reduction

• Borrego Wash Identified as largest contributor of sediment to Newport Bay– One of the few remaining channels with natural, unimproved segmentsunimproved segments

– Channel erosion with substantial stream incision– Severe stream bed degradation and widening

• Rapid urbanization of the watershed– Shea/Baker Ranch Property Development– Great Park– Great Park

• SWRCB identifies funds to be spent on Borrego Wash stabilization project

Project ObjectivesProject Objectives

Primary Project Objectives

• Sediment TMDLSediment TMDL

• Reduced erosion and sedimentation

• Minimizing hydraulic impact to existing floodplain

• Improving public safety

• Preservation of existing biological resources

• Protection of existing public infrastructure and facilities

Secondary Project Objectives

G d t h• Groundwater recharge

• Minimize increased sediment delivery 

• Habitat restorationHabitat restoration

• Public facility protection

Two Phase Study ApproachhPhase 1 – Baseline Existing Conditions Analysis

1 1 D t C ll ti d R h1.1  Data Collection and Research1.2  Field Stream Reconnaissance and Geomorphic  Assessment1.3  Previous Hydrology and Hydraulic Analysis Review1 4 Sediment Data Evaluation1.4  Sediment Data Evaluation1.5  Stream Characterization and Reach Identification1.6  Upstream Watershed Sediment Delivery Analysis1 7 Sediment Budget/Continuity Analysis1.7  Sediment Budget/Continuity Analysis1.8  Fluvial Model Development / Modeling – General Scour 

Analysis1.9 Fluvial Long Term Adjustment Modeling1.9  Fluvial Long Term Adjustment Modeling1.10  Assessment of Existing Stream Response and Channel 

Adjustment

Two Phase Study ApproachPhase 2 – Creek Stabilization / Restoration Alternatives Analysis

2.1 Constraints Analysis and Base Maps2.2 Conceptual Stabilization Alternative Formulation2.3 Preliminary Alternatives Alignment / Geometry / Layout2.4 Geomorphic Channel Restoration Elements2 5 Alternatives Preliminary Engineering General Fluvial Analysis /2.5 Alternatives Preliminary Engineering General Fluvial Analysis /

Hydraulic Sizing2.6 Proposed Conditions Alternatives HEC-RAS Floodplain

Hydraulics2 7 Fluvial Modeling Preliminary Alternatives2.7 Fluvial Modeling Preliminary Alternatives2.8 Hydraulic/Fluvial Model Assessment Restored Channel

Response/Stability2.9 Feasibility Analysis and Selection Recommended Alternative2 10 Pl i L l C t ti C t E ti t2.10 Planning Level Construction Cost Estimate2.11 Preliminary Phasing Analysis2.12 Creek Restoration/Stabilization - Preliminary Feasibility Report2.13 Stakeholder Presentation – Study Resultsy

Borrego Wash – Regional WatershedDrainage Area = 5.23 square milesQ100 = 5,200 cfs (Irvine Blvd.)

West Branch Watershed

Main Stem Creek

Foothill Ra

Study Reach10,500 ftToro

Regional Watershed SettingRegional Watershed Setting

Upstream LimitUpst ea t

Downstream Limit

Historical Erosion IssuesHistorical Erosion IssuesHistorical Erosion IssuesHistorical Erosion Issues

Previous Channel Erosion Studies

• Channel erosion studies initiated in 1982 by Stanley W. Trimble, UCLA Dept. of GeographyTrimble, UCLA Dept. of Geography

• In 1983, just under 200 cross‐sections installed across earthen channels of all sizes and types and surveyed

• Surveyed annually – new profiles added/subtracted

• By 1993, results showed that channel erosion furnished more than 50% of sediment yield from San Diego Creekmore than 50% of sediment yield from San Diego Creek

Watershed Channel Erosion Study 2006Watershed Channel Erosion Study 2006Dr. Stanley W. Trimble, UCLADr. Stanley W. Trimble, UCLA

Channel Erosion Studies in WatershedDr. Stanley W. Trimble, UCLA

Total Miles of Channel by Condition

Borrego Wash Watershed 1938 and 1983Borrego Wash Watershed 1938 and 1983

From: Trimble report, November, 2004

Lateral Bank Migration 1952 Lateral Bank Migration 1952 ‐‐20032003

From: Trimble report, November, 2004

Primary Sediment Source Reach ErosionPrimary Sediment Source Reach Erosion

From: Trimble report, November, 2004

Baseline Watershed Processes AssessmentBaseline Watershed Processes AssessmentBaseline Watershed Processes AssessmentBaseline Watershed Processes Assessment

Detailed Engineering Investigation Detailed Engineering Investigation andandPlan Formulation ProcessPlan Formulation Process

Establishobjectives andaims of project

Use guidinggeomorphic

principles for

Collect geomorphic

and physical data

Watershedhydrology and

rainfall

Evaluate physical and

environmentalsite conditions assessment Constraints /

Sediment Sources

Floodplainh d li

Analyze hydraulicd hi

Sedimentt t

Application ofi i l

Evaluatet tihydraulics and geomorphic

datatransport empirical

geomorphicrelationships

restoration Options and

technical assessment

Channel Sediment Source IdentificationChannel Sediment Source Identification

Geomorphic Assessment of Historical Sediment Volume Lost from topography changes

60%

25%25%

5%

10%

Watershed GIS DatabaseWatershed GIS Database

Vegetation Survey

Soil Types

Watershed LanduseWatershed Landuse

Watershed Erosion Potential Watershed Erosion Potential 

FEMA Flood Hazard MappingFEMA Flood Hazard Mapping

Geomorphic Historical TrendsGeomorphic Historical Trends

Stream Reach Identification / Characterization

• Evaluate hydraulically and geometrically similar lengths a uate yd au ca y a d geo et ca y s a e gt schannel– Statistical analysis to determine reach locations

• Average hydraulic parameters for reach

• Average sediment characteristics

• Average channel geometry

Borrego Wash – Reach Identification

Borrego Wash – Reach Identification

General Reach Characteristics

Reach No.

Description Length (ft) Avg. Slope

Entrance of wildlife corridor to existing grade control1

Entrance of wildlife corridor to existing grade control structure/dry weather crossing.

550 0.017

2Existing grade control structure/crossing to the downstream side of the existing landfill.

1,450 0.017

3Downstream end of existing landfill to existing grade control structure near utility corridor.

920 0.017

4Existing grade control structure to upstream end of existing landfill.

660 0.019

5Upstream end of existing landfill to downstream end of proposed Baker Ranch development.

1,300 0.018

6Downstream end of proposed Baker Ranch development to existing vertical drop immediately downstream of the 2,740 0.0166 existing vertical drop immediately downstream of the exposed sandstone channel section adjacent to the nursery.

2,740 0.016

7Existing vertical drop at sandstone channel section to upstream end of sandstone channel section.

480 0.052

Upstream end of sandstone channel section to upstream end8

Upstream end of sandstone channel section to upstream end of proposed Baker ranch development.

720 0.021

Streambed Profile VariationStreambed Profile Variation

Floodplain HECFloodplain HEC‐‐RAS Work Map RAS Work Map ––Cross Section LocationsCross Section Locations

Floodplain Hydraulic CharacteristicsFloodplain Hydraulic Characteristics

30

35 Legend

Vel Total 100-yr

Velocity Profile

15

20

25

Vel T

otal

(ft/s

)

Top Width Profile

400

g

Top Width 100-yr

5

10

Top Width Profile

300

Wid

th (f

t)

0 2000 4000 6000 8000 10000 12000 140000

Main Channel Distance (ft)

100

200

Top

0 2000 4000 6000 8000 10000 12000 140000

Main Channel Distance (ft)

Sediment  Continuity AnalysisSediment  Continuity Analysis

Borrego Wash 100-Year Storm Event Sediment Yield Summary - Aggradation/Degradation (Feet)

3 00

2.00

3.00

Yang

Van-Rijn

Ackers-White

0.00

1.00

R5 R4 R3 R2 R1

n/D

egra

datio

n MPM

-2.00

-1.00

Agg

rada

tion

-4.00

-3.00

Reach

Alternative Formulation ProcessAlternative Formulation ProcessAlternative Formulation ProcessAlternative Formulation Process

General Alternative ProcessGeneral Alternative Process

Technical Issues / ConstraintsTechnical Issues / Constraints

• Adjacent projects– Alton Parkway roadway – Shea / Baker Ranch– Wildlife Corridor– USMCAS/FAA Uses

• Physical constraints– Elevation/slope– GeologyGeology– Vegetation

• WatershedHydrology– Hydrology

– Sediment delivery• Other

ili i– Utilities

Alternative Creek Stabilization Methods

Technical Guidance for Natural Stream Stabilization Design

Alternatives – Reach Matrix

Category 2 – Flow Redirection

Category 3 – Structural Revetments

Category 3 – Structural Revetments

Category 4 – Other Structural Techniques

Category 4 – Other Structural Techniques

Category 5 – Biotechnical Techniques

Category 5 – Biotechnical Techniques

Category 6 – Channel Geometry Modification

Category 7 – Channel Alignment Modification

Category 7 – Channel Alignment Modification

Systems Alternative FormulationSystems Alternative Formulation

Summary of Systems Alternatives Summary of Systems Alternatives Generated From Initial ScreeningGenerated From Initial Screening

Alternative No. Identifier Alternative No. Identifier

1.1Rehabilitate Grade Control

5.1 Groins

1 2 New Grade Control 5 2 Bank Stabilization w/ Terraces1.2 New Grade Control 5.2 Bank Stabilization w/ Terraces

1.3Stabilized Bank Protection

5.3 Hybrid Combination

2.1Sediment Basin / Grade Control Only

6.1Stabilized Earth w/ Grade Control Channel Filly

2.2Groins / Terraced Channel

6.2Stabilized Earth w/ Grade Control Existing Channel Elevation

2 3Bank Stabilization / 

6 3 Bypass2.3Terraced Channel

6.3 Bypass

2.4 Minimum Stabilization 6.4 Stabilization

3.1Bank Stabilization/Groins / Terraces

7.1Stabilized Earth w/ Grade Control

Terraces

3.2Groins w/ Bank Stabilization

7.2 Cascade Step‐Pool

3.3 Minimum Stabilization 7.3 BypassGrade Control Stabilized Earth w/ Grade

4.1Grade Control Rehabilitation

8.1Stabilized Earth w/ Grade Control

4.2New Grade Control w/ Bank Stabilization

8.2 Bypass

Alternative Ranking Alternative Ranking –– Stakeholder ProcessStakeholder Process

Numerical Alternative Ranking Matrix

Numerical Alternative Ranking Matrix

Recommended Project SystemRecommended Project SystemRecommended Project SystemRecommended Project System

Recommended ProjectAlternative Identifier Description

1.3 Stabilized Bank ProtectionMaintain existing grade control. Toe protection opposite bank of roadway rip-

rap and stabilize eroded banks or areas of high potential erosion with vegetated planting and geotextile wrap. Join D/S Alton Parkway improvements.

2.3 Bank Stabilization / Terraced Channel

Stabilize existing eroded banks, slopes and install groins with floodplain terrace.

3.1 Bank Stabilization / Groins / Terraces

Stabilize eroded banks thorough regarded to stable slope, provide toe protection, create vegetated floodplain terraces outside active

f ff /Terraces streambed for vegetative buffer, and utilize rock bendway weirs/groins.

4.2 New Grade Control w/ Bank Stabilization

Abandon existing drop structure and construct two new grade control structures to break drop and stabilize narrow channel width section. Grade control located at the upstream and downstream ends of the narrow channel section.

Rock spurs / groins fields as well as the stabilized graded banks revegetated

5.3 Hybrid CombinationRock spurs / groins fields as well as the stabilized graded banks, revegetated

floodplain terraces with buried rock sill and brush windrows and created define active channel, stabilize eroded banks through reshaping, rock toe protection with brush layers (combines alt 5.1 and 5.2).

6 3 BypassParallel bypass RCB to divert main flood flows from Creek, stabilize existing

eroded channel banks through filling on Baker Ranch side and excavating on FAA side, stabilize bottom of existing channel with buried6.3 Bypass excavating on FAA side, stabilize bottom of existing channel with buried rock sills, provide toe protection each bank with brush layering, vegetate channel banks.

7.3 BypassParallel bypass RCB to divert main flood flows from Creek, stabilize existing

eroded channel banks through filling on Baker Ranch side and excavating on FAA side, stabilize bottom of existing channel with buried rock sills, provide toe protection each bank with brush layering,

t t h l b kvegetate channel banks.

8.2 BypassParallel bypass RCB to divert main flood flows from Creek, stabilize existing

eroded channel banks through filling on Baker Ranch side and excavating on FAA side, stabilize bottom of existing channel with buried rock sills, provide toe protection each bank with brush layering, vegetate channel banks.

Preliminary Stabilization Design

Reaches 1 & 2 – 2,000 ft

Reaches 1 & 2 – 2,000 ft

R h 1 $152 000Reach 1 = $152,000Reach 2 = $520,000

Reaches 3 & 4 – 1,580 ft

Reaches 3 & 4 – 1,580 ft

R h 3 $236 000Reach 3 = $236,000Reach 4 = $484,000

Reach 5 – 1,300 ft

Reach 5 – 1,300 ft

R h 5 $1 101 000Reach 5 = $1,101,000

Reach 6 – 2,740 ft

Reach 6 – 2,740 ft

Reaches 6 – 2,740 ft

Reach 6 = $6523000

Reach 6 – 2740 ft

Reach 6 = $6523000

Typical Sections Reach 7 & 8Typical Sections Reach 7 & 8

Reaches 7 & 8 – 1,200 ft

Reaches 7 & 8 – 1,200 ft

Summary of Construction CostsSummary of Construction Costs

Alternative IdentifierReach Length

(ft) Const. CostAlternative Identifier (ft) Const. Cost

1.3 Stabilized Bank Protection 400 $ 146,000.00

2 3Bank Stabilization / Terraced

Channel 1 400 $ 473 000 002.3 Channel 1,400 $ 473,000.00

3.1Bank Stabilization / Groins /

Terraces 1,100 $ 232,000.00

4 2New Grade Control w/ Bank

St bili ti 400 $ 477 000 004.2 Stabilization 400 $ 477,000.00

5.3 Hybrid Combination 1,040 $ 1,084,000.00

6.3 Bypass 2,700 $ 8,414,000.00

7.3 Bypass 475 $ 1,236,000.00

8.2 Bypass 725 $ 3,528,000.00

8,240 $ 15,590,000.00

Water Quality BenefitsWater Quality Benefits

• Reduction of sediment downstream to UNBeduct o o sed e t do st ea to U

• Removing major source of sediment making it difficult to achieve sediment TMDL

• Improving the water quality downstream San Diego Creek Channels

• Reducing sediment deposition in downstream habitat and sediment basins

• Intercepting urban dry weather flows for• Intercepting urban dry‐weather flows for restored vegetative corridor

Watershed Habitat RestorationWatershed Habitat Restoration

• Restoration of vegetative habitat corridor

• Creation of new habitat features within the• Creation of new habitat features within the adjacent floodplain

• Stabilization / protection of vegetation from erosion• Stabilization / protection of vegetation from erosion

• Connecting regional wildlife corridor to proposed Great Park Wildlife CorridorGreat Park Wildlife Corridor

• Creation of approximately 50 acres of new habitat