presentation program outline
TRANSCRIPT
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Presentation Program OutlinePresentation Program Outline
BACKGROUND / TMDLBACKGROUND / TMDL
WATERSHED CHARACTERISTICS
EROSION HISTORY
PLANNING PROCESS
ALTERNATIVE FORMULATION
BENEFITS - WATER SUPPLY / QUALITY / HABITAT
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Background &Watershed TMDLBackground &Watershed TMDLBackground & Watershed TMDLBackground & Watershed TMDL
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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
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Borrego Canyon WashBorrego Canyon Wash
Sam Diego Creek
Watershed
Borrego Canyon Wash
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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
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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
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History of Sedimentation Problem
• Changes in land use of area
• Ditch drainages artificially channeledartificially channeled into Upper Newport Bay
Upper Newport Bay
SedimSediment Plume
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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
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History of Sedimentation ProblemHistory of Sedimentation Problem
Upper Newport BayUpper Newport Bay
Sediment Plume
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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
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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
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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
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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
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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
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Watershed Monitoring
• 8 streamgaging/sediment i i imonitoring stations
• Based on land‐use– Open spaceOpen space
– Agriculture
– Construction
– Urban
– Mixed
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Fluvial Sediment Monitoring
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Bay Monitoring
• Topographic/Bathymetric p g p / yand Vegetative Monitoring
– Every 3 years
• Sediment sampling
– Bed, suspended
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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
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Project Objective & ApproachProject Objective & ApproachProject Objective & ApproachProject Objective & Approach
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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
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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
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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
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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
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Borrego Wash – Regional WatershedDrainage Area = 5.23 square milesQ100 = 5,200 cfs (Irvine Blvd.)
West Branch Watershed
Main Stem Creek
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Foothill Ra
Study Reach10,500 ftToro
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Regional Watershed SettingRegional Watershed Setting
Upstream LimitUpst ea t
Downstream Limit
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Historical Erosion IssuesHistorical Erosion IssuesHistorical Erosion IssuesHistorical Erosion Issues
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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
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Watershed Channel Erosion Study 2006Watershed Channel Erosion Study 2006Dr. Stanley W. Trimble, UCLADr. Stanley W. Trimble, UCLA
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Channel Erosion Studies in WatershedDr. Stanley W. Trimble, UCLA
Total Miles of Channel by Condition
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Borrego Wash Watershed 1938 and 1983Borrego Wash Watershed 1938 and 1983
From: Trimble report, November, 2004
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Lateral Bank Migration 1952 Lateral Bank Migration 1952 ‐‐20032003
From: Trimble report, November, 2004
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Primary Sediment Source Reach ErosionPrimary Sediment Source Reach Erosion
From: Trimble report, November, 2004
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Baseline Watershed Processes AssessmentBaseline Watershed Processes AssessmentBaseline Watershed Processes AssessmentBaseline Watershed Processes Assessment
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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
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Channel Sediment Source IdentificationChannel Sediment Source Identification
Geomorphic Assessment of Historical Sediment Volume Lost from topography changes
60%
25%25%
5%
10%
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Watershed GIS DatabaseWatershed GIS Database
Vegetation Survey
Soil Types
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Watershed LanduseWatershed Landuse
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Watershed Erosion Potential Watershed Erosion Potential
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FEMA Flood Hazard MappingFEMA Flood Hazard Mapping
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Geomorphic Historical TrendsGeomorphic Historical Trends
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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
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Borrego Wash – Reach Identification
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Borrego Wash – Reach Identification
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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
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Streambed Profile VariationStreambed Profile Variation
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Floodplain HECFloodplain HEC‐‐RAS Work Map RAS Work Map ––Cross Section LocationsCross Section Locations
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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)
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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
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Alternative Formulation ProcessAlternative Formulation ProcessAlternative Formulation ProcessAlternative Formulation Process
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General Alternative ProcessGeneral Alternative Process
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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
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Alternative Creek Stabilization Methods
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Technical Guidance for Natural Stream Stabilization Design
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Alternatives – Reach Matrix
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Category 2 – Flow Redirection
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Category 3 – Structural Revetments
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Category 3 – Structural Revetments
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Category 4 – Other Structural Techniques
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Category 4 – Other Structural Techniques
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Category 5 – Biotechnical Techniques
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Category 5 – Biotechnical Techniques
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Category 6 – Channel Geometry Modification
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Category 7 – Channel Alignment Modification
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Category 7 – Channel Alignment Modification
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Systems Alternative FormulationSystems Alternative Formulation
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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
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Alternative Ranking Alternative Ranking –– Stakeholder ProcessStakeholder Process
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Numerical Alternative Ranking Matrix
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Numerical Alternative Ranking Matrix
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Recommended Project SystemRecommended Project SystemRecommended Project SystemRecommended Project System
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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.
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Preliminary Stabilization Design
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Reaches 1 & 2 – 2,000 ft
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Reaches 1 & 2 – 2,000 ft
R h 1 $152 000Reach 1 = $152,000Reach 2 = $520,000
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Reaches 3 & 4 – 1,580 ft
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Reaches 3 & 4 – 1,580 ft
R h 3 $236 000Reach 3 = $236,000Reach 4 = $484,000
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Reach 5 – 1,300 ft
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Reach 5 – 1,300 ft
R h 5 $1 101 000Reach 5 = $1,101,000
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Reach 6 – 2,740 ft
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Reach 6 – 2,740 ft
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Reaches 6 – 2,740 ft
Reach 6 = $6523000
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Reach 6 – 2740 ft
Reach 6 = $6523000
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Typical Sections Reach 7 & 8Typical Sections Reach 7 & 8
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Reaches 7 & 8 – 1,200 ft
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Reaches 7 & 8 – 1,200 ft
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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
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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
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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
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