embankment remediation project - california … dam remediation project slide 3 local faults could...

Overview of theEmbankment Remediation

Project

May 2015

Perris Dam Remediation Project

Location of Perris Dam and Lake

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State Water Project

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Local Faults Could Produce Large Motion That Affects Dam

Design Earthquake - San Jacinto Fault ZoneMagnitude Mw7.5 @ 5 miles from Dam

Dam Features

• Construction 1970 – 1972• Type of Dam – Earthfill• Dam Height – 126 feet• Dam Length – 2.2 Miles

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Embankment Design and Construction

• Embankment Section– Primarily Silty Sand– Inclined Sandy Clay Core– Compaction Requirements

• DWR Standard– (20,000 ft-lb/ft3)

ZoneSpec.70-25

AverageAs-Placed

1 97% 98%2 97% 101%

Zone 1

Zone 3Zone 4

Zone 2Zone 2

Crest El. = 1600 ft

Toe El. = 1480 ft

41 3.2

1

31

11

0.51

Zone 2

10' Riprap

Dam Axis

Bench

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Embankment Design and Construction

• Foundation Preparation– 3 ft excavation beneath Zone 2

• Remove organic material & loose surface sands

– 6 ft excavation beneath Zone 1 (core)• 10-25 ft Core Trench

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Example of Cross Section Evaluation

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Material moist (pcf) sat (pcf) K2,max ' (deg) c' (psf)  (deg) c (psf) Kh (ft/day) Kh / KvZone 1 128 134 0.35 100 22 600 14 1000 0.01 10Zone 2 134 139 0.35 100 33 0 13 1800 0.1 10Zone 3 134 139 0.35 100 40 0 40 0 5 1Zone 4 134 139 0.35 100 40 0 40 0 5 1

Shallow Alluvium 129.5 136 0.35 160 35.5 0 23 500 0.5 10Deep Alluvium 129.5 136 0.35 160 35.5 0 14 2300 0.5 10Weathered Rock 145 145 0.32 N/A N/A N/A N/A N/A 0.5 10

Bedrock 165 165 0.28 N/A N/A N/A N/A N/A 0.01 10

Summary of Field ExplorationSPT Drill Holes = 120

SPT’s = 1,318CPT Drill Holes = 139

Red Areas Indicate Problem Soils

Design Evaluated with FLAC

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RemediationZone

RemediationZone

Perris Dam and Lake

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Design and Review

• Division Of EngineeringResponsible for design, development of plans and specifications, administration and inspection of construction contract

• Division of Safety of Dams (DSOD)As dam regulator, ensures a safe design

Approves design analysis, plans, and specifications

Oversees the construction in accordance with the approved designs

• Board of Consultants (BOC)Appointed by the Director of DWR

Comprised of a group of experts

Performs independent review of the dam design

Approves design work for construction

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Design Concept

• Remove and replace loose shallow soils

• Improve the deeper foundation soils by CementDeep Soil Mixing (CDSM)

• Construct a stability berm on the downstream sideof the dam and include drainage features

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Perris Dam Remediation Project Slide 12

• Clearing and Grubbing• Lake Bed Haul Roads• Sitework• Production Blasting• Controlled Blasting• Rock Processing and Stockpiling (Filter and Drain)• Dewatering at Dam Toe and Borrow Area• Seepage Collection System (Remove and Replace)• Relief Well System (Remove and Replace)• Cement Deep Soil Mixing (CDSM)• Stability Berm• Right Abutment Dam Repair

Construction ContractScope of Work

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Project Overview

Foundation Treatment and Stability Berm

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Foundation Treatment

CDSM

Berm

Removal and Replacement

New Haul Road

Outlet Structure

Controlled Blasting

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Controlled Blasting

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•Low ground velocity restriction

•Protect existing facilities

Production Blasting

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Production Blasting

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Rock Processing and Stockpile

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•Rock from blasting usedfor filter and drainsystem

•Cleanness requirements

•Segregation requirements

•Limited work andstaging areas

Seepage Collection System

Perris Dam Remediation Project October 31, 2013 Slide 21

•Manage the existing system's flowing water

• Remove existing wells and drain system

• Construct new system at berm

Design Phase Test Sections

• DWR conducted testing to evaluate design andconstruction of the foundation treatment, otherconstruction features, dewatering.

• Identified potential problems• Provided confidence in the design• Refined design of foundation repairs. Resulted in final design

with shallower excavation and confirmed CDSM treatment.

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Test Sections

Dewatering Test Excavation Area

CDSM Test Section Area

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Test ContractPre-drilling

Perris Dam Remediation Project October 25, 2013 Slide 24

Test ContractSoil Mixing using Multi-Auger Method

Multi-Auger Rig

Installing CDSM Test Cells

Spoil Area

Batch Plant

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Test Section Soil mixing using CSM method

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CDSM Spoils

Spoil Trench

Test Section - Soil Mixing Operation

Multi-Auger Method CSM Method

CSM Spoils

Spoil Trench

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Sheet PilesEductor Wells

Large Dewatering Wells

next view

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Evaluated Dewatering Methods

Evaluated Excavation and Drilling Methods

Dewatering Test Excavation

Geologic Investigation

Large WellLarge Well

Eductor Wells

Sheet Piles

Geologic Investigation

Dewatering Test Excavation

http://www.water.ca.gov/lakeperris/Perris Dam Remediation Project Slide 30