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Overview of theEmbankment Remediation
Project
May 2015
Perris Dam Remediation Project
Location of Perris Dam and Lake
Perris Dam Remediation Project Slide 2
State Water Project
Perris Dam Remediation Project Slide 3
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
Perris Dam Remediation Project Slide 4
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
Perris Dam Remediation Project Slide 5
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
Perris Dam Remediation Project Slide 6
Example of Cross Section Evaluation
Perris Dam Remediation Project Slide 7
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
Perris Dam Remediation Project Slide 8
RemediationZone
RemediationZone
Perris Dam and Lake
Perris Dam Remediation Project Slide 9
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
Perris Dam Remediation Project Slide 10
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
Perris Dam Remediation Project Slide 11
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
Perris Dam Remediation Project Slide 13
Project Overview
Foundation Treatment and Stability Berm
Perris Dam Remediation Project Slide 14
Perris Dam Remediation Project Slide 15
Foundation Treatment
CDSM
Berm
Removal and Replacement
New Haul Road
Outlet Structure
Controlled Blasting
Perris Dam Remediation Project Slide 16
Controlled Blasting
Perris Dam Remediation Project Slide 17
•Low ground velocity restriction
•Protect existing facilities
Production Blasting
Perris Dam Remediation Project Slide 18
Production Blasting
Perris Dam Remediation Project Slide 19
Rock Processing and Stockpile
Perris Dam Remediation Project Slide 20
•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.
Perris Dam Remediation Project Slide 22
Test Sections
Dewatering Test Excavation Area
CDSM Test Section Area
Perris Dam Remediation Project Slide 23
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
Perris Dam Remediation Project Slide 25
Test Section Soil mixing using CSM method
Perris Dam Remediation Project Slide 26
CDSM Spoils
Spoil Trench
Test Section - Soil Mixing Operation
Multi-Auger Method CSM Method
CSM Spoils
Spoil Trench
Perris Dam Remediation Project Slide 27
Sheet PilesEductor Wells
Large Dewatering Wells
next view
Perris Dam Remediation Project Slide 28
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