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Presentation Topics Outline
SMWD Alternative Water Supplies
Background /Objectives / Funding
Watershed Planning / Constraints
Design and Hydraulic Operation
Basin Design Features
Basin Construction
SMWD Water Supplies / Alternative Sources
Santa Margarita Water District
SMWD Service
Area
• 50th Anniversary• Provides Water and Wastewater Service to over
155,000 residents• Over Next 20-30 years ~40,000 More Residents
Indoor Use13,400 AF
(February low flows)
27,000 AF Potable Water
MWD
Outdoor Use13,600 AF
WastewaterChiquita, 6.4 MGD, 7,200 AFOso Creek, 2.0 MGD, 2,200 AFSOCWA, 2.2 MGD, 2,500 AF
Ocean Outfall6,300 AFRecycled Water
5,600 AFChiquita, 3,800 AFOso Creek, 1,800 AF
Runoff
Urban Return Flows1,800 AF
Oso Barrier, 1,120 AFHorno Basin, 180 AFTrabuco, 300 AFDove Canyon, 200 AFFuture: Gobernadora
SMWD 2014 Water Supply
District’s Existing RW System
• ~ 2,740 Dedicated Irrigation Meters
• ~ 1,260 Non-Domestic• Future ~ 3,000 Non-Dom
Coto de Caza Non-Domestic System
Currently • Usage ~ 1,370 afy• Purchase 1,210 afy
MWD water• 160 afy well water
SMWD Proactively Seeks Multiple Types of Non-Potable Sources
8
• Reclaimed Water– Oso Creek WRP (2.0
MGD)– Chiquita WRP (5 MGD)– SOCWA, IRWD, TCWD
• Urban Runoff Capture– Oso Creek Barrier Project– Dove Canyon Basin– Horno Basin
• Imported Water (Portola Reservoir)
Non-Domestic Irrigation
Water Sources
Imported Water
Urban Runoff
Capture
Recycled Water
SMWD Leader in Sourcing Dry Weather Nuisance Flow for Recycled Water
9
Oso Creek Barrier ProjectConstructed 1970’s – Modified 2008
Oso Creek Barrier Diversion Operated Successfully for > 35 Years
10
– 2 Million Gallons Per Day– Mixes w/ Oso Creek WRP Effluent– Pumped to Upper Oso Reservoir
Facility Planning Background and Objectives
Gobernadora Detention Basin Location
Basin Location – Aerial Image (2006)
Coastal Sage
Gobernadora Environmental Restoration Area
Coto de Caza
Design Constraints• Groundwater• Biological Habitat• Available R/W• Floodplain• Topography• Natural alluvial
Creek
Basin Provides Multiple Objectives / Benefits
Groundwater Recovery
Stormwater Treatment Flood Peak Attenuation
Stream Stabilization
Groundwater Infiltration
Project Background and Objectives
• District’s Goals– Capture Urban Runoff– Protect Downstream Facilities
• 10” and 16” sewer force main• 36” Regional Water Transmission Main
• RMV/OC Public Works– Storm water management– Protect downstream GERA
• OC Parks– Connect two Regional Wilderness Parks
• Multiple Benefits for Multiple Partners• Improved/Leverage Funding Opportunities
• Reuse Urban Runoff up to 800 afy• Possible Forebay for additional xfer of RW
for add’l 400 afy• Reduce Impacts of Storm Events• Stream Stabilization• Improved OC Parks Trail System
Gobernadora Multi-Purpose BasinNon-Domestic Water Supply
Cost and Funding Sources
17
Total Project Cost
$23.4 M
RMVLand Transfer Value
($2.0M)
RMV Cash Contributions
($9.8 M)
SMWD General Fund Contributions
($0.2 M)SMWD
CFD ($3.2 M)
OC ParksCash Contribution
($0.7 M)
Prop. 50 Funds($2.5 M)
Prop 1E Funds($5.0 M)
Regional Watershed Planning
Regional Watershed Analyses
• San Juan Creek = 176 sq. miles• RMV SJC Watershed = 20.85 sq. mi.
SJC U/S RMV = 79 sq. mi.SJC D/S RMV = 106 sq. mi.
RMV Ranch Plan Development
Highlights of Stormwater Facilities• 32 miles storm drain pipe• 21 storm drain outfalls to creeks (27
total reserved 6 future use)• 22 detention basins – 8 regional• Local Detention Basin areas = 87.8 acres• Regional Detention Basin = 87.8 acres• WQ Basin areas = 46.8 acres• HM Basin areas = 88.2 acres
Facility Planning – Existing Conditions & Constraints
Hydrology – Tributary Watershed Characteristics
Gobernadora Watershed = 3,797 acres
Wagon Wheel Watershed = 1,128 acres
Site Field Characteristics
Site Field Characteristics
Existing Creek 100-Year Floodplain
Gobernadora Creek Experienced Significant Erosion and Sedimentation Issues• Constant amount of urban dry weather flows• Erosion of the proposed basin area with 3 acres loss
of land• Sedimentation downstream
March 2005
“prevent this from happening”
Source: Balance Hydrologics, Inc., 2006
Creek Erosion Between Preliminary to Final Design
• Preliminary design performed in 2008.
• Large storm event December 2010
• Erosion between Preliminary Design reduced available footprint of basin by over 3 acres
• Increased environmental regulatory areas
High Groundwater Near Surface
Overview of Proposed Facility
Existing Site Condition – Pre-project
Milestone No.1 Construction
Milestone No.2 – Completed Basin
Division of Basins
Peak Flood Attenuation FromUpper (35 AF) and Lower (100 AF) Basins
Basin Embankment SectionLength DSOD
JurisdictionStorage Volume
Embankment Height
Variation
Embankment Height from
SpillwayUpper Basin 1,400 feet No 34 AF 10-15 feet 7.4 feet (wall)
Intermediate / Separation Berm
900 feet No N/A 12 feet 4.3 feet
Lower Basin 1,440 feet No 2(49 AF) 15-16 feet 12 feet
Primary Spillway Hydraulics / Dissipator
• Trapezoidal broad crest weir• Tumbling flow element dissipator• Designed for intercepted Q1500-year = 3,400 cfs
– Maximum flow depth y1500-year = 3.2 feet
Facility Operation – Dry Weather / Flood Flows
Milestone No.2 – Completed Basin
Inflatable Dams – Upper Basin
Inflatable Dams – Flood Flow Conditions
Inflatable Dams – Dry Weather Diversion
Lateral Channel Side-Weir Hydraulic Performance
• Weir Length = 200 feet• Sharp Crest Weir• Height above channel = 7.4 feet• Crest to top channel = 6.3 feet • Downstream Rubber Dam = 6 feet
Side Weir Hydraulics – Spatially Varied Flow Analysis
Storm Event Hydraulic method Lag (hr) Runoff (ac-ft) Peak Flow
(cfs)Bypass (cfs)
Channel To Basin (cfs)
2-yr EV 1.279 118.0 387 387 0
5-yr EV BAS 1.067 217.9 803 803 0
10-yr EV BAS 0.938 432.2 1848 1575 273
25-yr EV BAS 0.856 732.6 2695 2043 652
50-yr EV BAS 0.821 873.2 3159 2269 890
100-yr EV BAS 0.795 991.6 3630 2500 1130
100-yr HC (AMCIII) BAS 0.73 1796.3 5329 3320 2009
100-yr HC (AMCIII) with Sediment HEC-RAS 0.73 1796.3 5329 2807 2522
1000-yr HC (AMCIII) BAS 0.73 2637.5 7665 4405 3260
1500-yr HC (AMCIII) BAS 0.73 2784.6 8057 4585 3472
Normal Dry Weather Conditions – Water Reuse Functions
Upper Basin Water Quality Treatment & Recharge
12
3
4
Dry weather diversion gated culvert
Return Water Flow for habitat
SMWD Pump Station
UPPER BASIN
LOWER BASIN
Force Main
Dry Weather Flow Diversion Operation
Two 80’ Deep Recovery Wells that Lift to Distribution Pumps’ Suction
50
Groundwater Wells
Pumping Facility Embedded into Side of Upper Basin to Draw Flows
51
Upstairs Electrical Control Room
Isolation Valves from Basin (storm flows and maintenance
Access Hatches to Wet and Dry Wells
Inflow from BasinHabitat Return flow to creek
Force main to upper reservoir
Water Reclamation Pump Station Designed w/ Four Different Sections
12
34
Basin Inflow
Creek Habitat Return FlowQmin= 0.3 cfs
Force main to Reservoir
Pumping Facility has Desilting, Straining, and Return Flow to Creek
53
Pump Station Features:
• 2 Blowers Rubber Dams• 2- 100 hsp pumps (500
gpm each 550 ft head)• VFD
• Hydroneumatic tank for force main
• PLC and Manual Controls• SCADA radio control
Flood Flow Operations
Channel Side Weir
Upper to Lower Basin Spillways
Outlet Spillways to Channel
Gravity Outlet
LOWER BASIN = Flood Control
Lower Dam Inflated
Upper Dam Deflated
Gravity Outlet
Flood Flow Operations – Specialty Features
Lower Dam Inflated
Upper Dam Deflated
Portable Generator Connection
Manual Dam Control
Stream Gauge Sensor 1
Stream Gauge Sensor 2
Flood Control Operation
Flood Control Operation – Lower Dam Inflated• Intercept Q=2,000 cfs out of the Q100 = 5,330 cfs• D/S Flood Control Rubber Dam height = 6 ft
• Hydraulic control for side weir operation• Stilling well at rubber dam with water level transducer
• Height of Side Weir = 7.4 ft• Total Project Flood Storage = 99 (D/S) + 34 (U/S) = 133 AF
Project Design Features Construction – Pump Station
Pump Station Structure Foundation
Pump Station Structure Initial Construction Item
Pump Station & Creek Return Pipe
Pump Station – Constructed
Pump Station – Dry Well
Pump Station – Dry Well
Pump Station Construction
65
Project Design Features Construction – Rubber Dams
North Dam Foundation
Inflatable Dam Installation Process
73
Inflatable Dams – Installed
Project Design Features Construction – Side Weir
Channel Side Weir - Installed
Project Design Features Construction – Basin / Embankment
Perimeter Embankment Section
Embankment Stability Analysis
Primary Outlet Spillway to Channel
Two Separate Gated Low Level Outlet
Low-Level Outlet Lower Basin
Temporary Creek Relocation – Water Control
Extensive Groundwater Dewatering Operation
Revetment Installation
Project Design Features Construction – Primary Spillway
Summary - Unique Multipurpose Water Resources Facility
• Automated operation for dry / flow floods• Multiple benefits beyond flood and water
recycling leverage public grant funding• Successful public/private partnership• Dual agency operation and maintenance• Innovative hydraulic operation through
flexibility provided by inflatable dams