2024.02.06 Prado Dam Spillway Modifications - Pre Bid Conference SAMS Version.pdf

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For Official Use Only (FOUO) // Unclassified This document is FOR OFFICIAL USE ONLY (FOUO). It contains information that may be exempt from public release under the Freedom of Information Act (5 USC 552). It is to be controlled, stored, handled, transmitted, distributed, and disposed of in accordance with USACE policy relating to FOUO information and it is not to be released to the public or other personnel who do not have a valid “need to know” without prior written approval of an authorized USACE official.

For Official Use Only (FOUO) // Unclassified This document is FOR OFFICIAL USE ONLY (FOUO). It contains information that may be exempt from public release under the Freedom of Information Act (5 USC 552). It is to be controlled, stored, handled, transmitted, distributed, and disposed of in accordance with USACE policy relating to FOUO information and it is not to be released to the public or other personnel who do not have a valid “need to know” without prior written approval of an authorized USACE official.

06 February 2024

PRADO DAM

SPILLWAY MODIFICATIONS

PRE-BID CONFERENCE AND

SITE VISIT

AGENDA

Project Design Team Project Site Visit Logistics Project Background Project Objectives Design Challenges Design Overview Life Safety Risks During Construction Preconstruction Services and Early Work Items RFI’s and IDaC

DRIVING DIRECTIONS TO PRADO VISITOR’S CENTER

• While traveling East on I-91 from Orange County, exit at Exit 47 at Serfas Club / Auto Center Drive.

• At the light, turn left (North) onto Auto Center Drive.

• Then proceed straight through the next two traffic lights.

• After the crest of the bridge (beyond the West Corona Train station), turn left on Pomona- Rincon Drive (there is not an accurate street sign). Once you turn left, the business Duralum will be on your right.

• Follow this road straight past the guard shack to the Prado Office Trailer complex. Park in the visitor parking on the right, which is the parking lot outside of the fenced complex.

Address:

Prado Dam Visitor’s Center 2493 Pomona-Rincon Rd Corona, CA 92878

Do not put Prado Dam into your phone!!

PARKING FOR PRADO PRE-BID SITE VISIT STOP #1

POC: MAJ Sean Hutchison

USACE: 951-455-6523

N

SITE TOUR

Spillway

Outlet Works

SR-91

SR71

Dike

Main Embankment

Auxiliary DikeNN

PROJECT BACKGROUND

Project History

Original Prado Dam constructed from 1938 to 1941 Flooding in 1938 resulted in 115 deaths and $1.6B

(2022 dollars) Primary purpose is flood control Reservoir generally dry

Project History

1980’s studies concluded that the dam would only provide a 70-year level of flood protection and could not safely pass the PMF

Part of ongoing Santa Ana River Mainstem (SARM) Project to improve flood protection and infrastructure along 75 miles of the Santa Ana River – authorized in 1986

Spillway Raise Project to increase the spillway crest 20 feet originally authorization in 1986

Embankment was raised 28.4 feet and a new outlet works was constructed from 2004 to

Outlet Works

Main Embankment

SR-71 DikeSR-71

OW

Discharge Channel

Spillway

Ogee Crest Structure

SR-91

Auxiliary Dike Embankment

NN

EXISTING SPILLWAY

PROJECT OBJECTIVES

Elevated risks associated with the spillway chute were identified in 2019 and a DSMS was subsequently initiated in February of 2020 Missing critical spillway defensive measures

No foundation anchors No waterstops No continuous reinforcement across joints Undersized slab with single mat of reinforcement Erosion resistant foundation Joint offsets into flow

Individual Risk = probability of loading x probability of failure

Societal Risk = probability of loading x probability of failure x consequence

This is a consequence driven project with a significant downstream PAR

Prado TTX – Spillway Modifications Project Update

Prado Dam

SARM Spillway Raise

Dam Safety

Prado Spillway Modifications

DESIGN CHALLENGES

Challenging foundation conditions Mudstone and poorly cemented sandstone Vertical jointing Foundation defects consisting of faults and shears Low strength Expected settlement Swell pressures

DESIGN CHALLENGES

Significant seismic hazard OBE = 0.32g MCE = 1.14g

DESIGN OVERVIEW

Left Embankment Connection

Right Embankment Connection

Arced Labyrinth Control

Structure

New Spillway Flat Chute

50’x50’ Slabs

New Spillway Chute Walls –

40’ Tall

New Steep Chute Slab and Walls

RCC

Foundation

Access Roads and SART not shown

Crest El.

576.0

Crest El.

565.5 Crest El.

575.5

Crest El.

563.0

Crest El.

563.0

Crest El.

573.5

Crest El.

574.0

Invert El.

535.0

12’x15’ Gated Access Portals

Composite Embankment Connection

Composite Embankment Connection

Borrow Areas (primary)

Staging and Stockpile

Areas

Fill Areas

Batch Plant Exclusion

AreasBorrow Areas (if needed)

Site Access

N

Foundation Preparation Shaping and treatment Slaking bedrock Removal of swelling materials below chute slabs Mud mat, dental concrete, slush grout

Fine grained materials and shears in chute

Shears and faults beneath the control structure

Dewatering Contractor design Dewatering specialist GDR and GBR High on left drops off to the right Alluvium groundwater sensitive to reservoir pool but always subject to nuisance groundwater at depth

Wells and well points in alluvium is required

Regional Groundwater

Flows

Monoliths separated by control joints in slab and contraction joints in

RCC

Slabs discretized by construction joints

Wall heights ranging from 28 feet to 41 feet tall

Change in elevation at downstream nose walls

Labyrinth reinforcement drawings included in solicitation package

Remaining features reinforcement drawings still under development

Pounds of reinforcement per cubic yard was included in Amendment 4

Nose wall reinforcement is very congested

Slotted 8” C900 PVC Pipe Solid 8” C900 PVC Pipe Slotted 18” C900 PVC Pipe Solid 18” C900 PVC Pipe Slotted 12” C900 PVC Pipe Solid 12” C900 PVC Pipe

Left embankment toe drain right embankment toe drain

Groundwater collection pipe

Left chute collection pipe

Right chute collection pipe

DESIGN

OVERVIEW

RCC embankment connection monoliths (right and left side) Reinforced grout enriched vibrated RCC for exterior faces Embankment placement in conjunction with RCC placement

RCC Corner monoliths Reinforced concrete walls buttressed with RCC Anchored at interface

Embankment connections Zoned earthfill Zone I is Zone II and vice versa Zone II interface with RCC Filters and drains are continuous Toe drains for each side Built concurrent with RCC

– RCC to lead embankment placement by no greater than 5 feet

Structural connection and joint types Flat chute slab control joint Longitudinal and transverse Centered over underdrains Keyed Waterstop Lap splice bars Bond breaker

Structural connection and joint types (cont.)

Steep chute slab control joint Generally same as flat chute No underdrains Leveling concrete instead of

RCC

Foundation key pedestal and reinforcement joint types (cont.)

Slab to wall footing contraction joint Plain dowel Double waterstop Bond breaker No key Longitudinal drain joint types (cont.)

Wall footing to wall footing control joint Keyed Waterstop Lap splice bars Bond breaker joint types (cont.)

Wall stem to wall stem contraction joint Plain dowel Single waterstop Bond breaker No key

New Access Roads and SART Recreational trail O&M access roads for underdrain collection and conveyance system

Surface drainage features currently under design

EVALUATION OF CONSTRUCTION SEQUENCES

Eight alternatives evaluated in total Discretized by construction seasons

Dry Season – April 16 to Nov 14 Wet Season – Nov 15 to April 15

Hydrologic loading for each sequence step Independent evaluations of four alternatives Design Team Evaluation Risk Team Evaluation

Part A

1. Control structure to El.

2. Cycles 1 and 7 to El. 567

3. Demo chute slabs and place RCC

4. Corner monoliths RC walls to El.

CURRENT PREFERRED CONSTRUCTION SEQUENCE

Wier wall (Cycles 1) to El 567

Wier wall (Cycle 7) to El

Corner monolith

Corner monolith

Left cofferdam Temporary RCC Abutment El 567

Control structure weir walls (Cycles 2‐6) to El 543

Demo and place RCC

CURRENT PREFERRED CONSTRUCTION SEQUENCE

Right cofferdam El 567

Ogee demo to El. 535.0

Embankment connection to El. 567

Embankment connection to El. 567

Left cofferdam 567 Slab and Wall construction

Part B

1. Cofferdams to

El. 567 connected to Cycles 1 and 7

2. Corner monoliths to El.

3. Embankment connections to El. 567

4. Continue chute slab and wall construction

Embankment connection to El. 594.4

Control Structure to final crest elevations

Remove cofferdams

Slab and Wall construction

Embankment connection to El. 594

1. Cofferdam removal

2. Embankment connections to El. 594.4

3. Continue chute slab and walls

4. Control structure to final crest elevations

PRECONSTRUCTION SERVICES

Collaboration Workshop

Contractor Deliverables

• Construction Sequencing

Plan

• Constructability Report

• Design Conflicts Analysis

Report

• Construction Schedule

• Construction Cost Estimate

Government Deliverables

• Life Safety Risk Analysis

Report

• Least Risky Construction Sequence

• Vested Construction Plan Ready for Execution

• Prepared Site Ready for Construction Production

EARLY WORK ITEMS

EARLY WORKING ITEMS

Clearing and Grubbing Must be completed outside the nesting season – September 16 through February 14

Once completed must be maintained Environmental requirement

Soundwall Installation Must be completed outside the nesting season – September 16 through February 14

Once completed must be maintained Environmental requirement

EARLY WORK ITEMS

SCG Gas Removal Abandoned gas line beneath footprint of right embankment connection

Backfilled with grout Differing information regarding exact location – three potholes

BID SCHEDULE

BID SCHEDULE

CONSIDERATIONS AND RESTRICTIONS

Working hours Monday through Friday – 7:00am to 6:00pm Excludes federal holidays Exceptions for concrete placements subject to municipal noise restrictions Site security Transient population resides in reservoir limits Security program submittal Security manager

Construction work limits

Wildlife Corridor

Wildlife corridor Provide and maintain a minimum of 12 feet of walkable space through the wildlife corridor at night and during all non‐work hours for wildlife to use.

If the wildlife corridor requires temporary blocking for construction purposes, the total blocking time may not exceed 24 hours or two consecutive nights without prior coordination and approval by Contracting Officer

Haul roads All haul roads withing CWL are available for use Improvements subject to approval by the Contracting Officer Pre and post construction survey required

Water for construction Reservoir water may not be used for construction

IDAC AND RFI’S

Drawing package 310 total drawings 192 drawings issued as part of solicitation 26 drawings issued “for construction” as part of early work items 118 additional drawings will be available to successful offeror

Majority of reinforcement drawings Additional excavation sections and details Additional sections and details for access roads and SART Surface drainage plans, sections, and details Swing gate sections and details Miscellaneous details

IDAC AND RFI’S

Consider uniqueness of early contractor involvement for this project

Non-IDaC drawings will not be made available for proposal phase Electronic files will not be made available Utilize all available information Bid quantities provided in the bid schedule Thermal restrictions for mass concrete placements