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

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• 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

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Oso Creek Barrier ProjectConstructed 1970’s – Modified 2008

Oso Creek Barrier Diversion Operated Successfully for > 35 Years

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– 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

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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

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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

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Groundwater Wells

Pumping Facility Embedded into Side of Upper Basin to Draw Flows

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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

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34

Basin Inflow

Creek Habitat Return FlowQmin= 0.3 cfs

Force main to Reservoir

Pumping Facility has Desilting, Straining, and Return Flow to Creek

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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

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Project Design Features Construction – Rubber Dams

North Dam Foundation

Inflatable Dam Installation Process

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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