Oroville Emergency Spillway Repair Owner: CA Dept. of Water - - PowerPoint PPT Presentation

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Oct 11, 2022 456 likes •705 views

Oroville Emergency Spillway Repair Owner: CA Dept. of Water Resources (DWR) General Contractor: Kiewit Drilling Subcontractor: Drill Tech Drilling & Shoring, Inc. Presented by: Brett K. Mainer, P.E., G.E. Drill Tech Drilling &

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Oroville Emergency Spillway Repair

Owner: CA Dept. of Water Resources (DWR) General Contractor: Kiewit Drilling Subcontractor: Drill Tech Drilling & Shoring, Inc.

Presented by: Brett K. Mainer, P.E., G.E. Drill Tech Drilling & Shoring, Inc.

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Secant Pile Scope of Work

605ea secant piles (5 piles per panel – 121ea

panels)

35’ to 92’ in depth
36” diameter piles spaced 24” on center
Minimum depth into fresh rock = 15’
Rebar cages in secondary piles

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Site Settings, Geological Data

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Top of Guide Wall Top of Secant Piles Wall Planned Fresh Rock Elevation Actual Drilled Tip Elevation New Plan Pile Tip Elevation

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Installation Procedure

Guide Wall was excavated / formed / poured
Overburden (fill, topsoil and weathered rock) was drilled with conventional

rotary drills using core barrels

Holes were flattened using a “hole flattener”, which is a modified core barrel
Magnets inserted in hole to retrieve any steel left behind
Downhole hammers (BG-50/BG-40/RTG-25) were used to punch through

rock to planned depth

Hole cleaning with cleanout buckets and spin bottoms
Rebar cage placement in secondary piles
Concrete placement

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Drill Equipment Summary

Overburden:
Bauer BG-40 1)
Bauer BG-24 (2ea)
Hammer:
Bauer BG-50
Bauer BG-40
Bauer RTG-25 (2ea)

1) Replaced with BG24 in Nov 2017 when needed on another project

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BG-40 BG-24 BG-50

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BG-50 RTG-25 BG-24

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Hole Flattener

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Hammer Drill Set Ups

3 large air compressors per Hammer Drill
Combinations of 1300cfm, 1600cfm and 1170cfm compressors
Desired pressure to maintained = 200-225psi
Multiple hammer combinations used
Mono Hammers the primary tool
Center Rock Hammers and Bits
Atlas Copco Hammer and Bits
Cluster Drills Also used for Primary Holes only
Center Rock Cluster Drill
Keystone Cluster Drill

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Hammers (Mono and Cluster)

Mono hammer Keystone Cluster Hammer Center Rock Cluster Hammer

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Hammer production rates

Total hammer drill rig shifts:
552 shifts during 162 operation days.
Average production per rig shift:
37.65 LF/rig shift.
Average production per operation day:
128.3 LF/day.

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Challenges

Rock strengths 30,000psi to 52,000psi
Rock strata was primarily composed of amphibolite
Constant destruction of tooling (Total Tooling Bill > $3M)
Concrete Placement in Hot Weather
Ground Water
Allowable Verticality Tolerance = 1.5” per 10’ = 1.25%
With only 12” of theoretical primary pile between secondary piles,

piles over 40’ in depth could still be in tolerance and intersect

Rain during the winter months

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Drilling Sequence

1st drilling sequence:
A-E-C
C-A-E
Secondary (B-D) piles
Deep Secondary Drill Holes would wander through the C piles and intersect
Sequence Revised to:
C-C-C
A-A-A
E-E-E
Secondary (B-D) piles

A B C D E A B C D E

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Drill Tech QC Form

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Job Quantity Summary

Number of Piles 605 Overburden Drilled 13,312 LF Fresh Rock Drilled 20,781 LF Total Weight of Cages 1,074,800 lbs Total Concrete Poured 11,580 CY Total Manhours Worked 61,708 Hrs Total Recordable Injuries

ZERO

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Final Accomplishment

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