This document summarizes a presentation about using explosive compaction to improve ground conditions at the Seymour Dam in Vancouver, BC. Explosive compaction involves drilling holes, inserting explosive charges at intervals, and detonating them to densify soils from 50-80 feet deep without excavating. It describes the existing dam, need for upgrading, explosive compaction process used including panel development, drilling, blasting, and extensive monitoring of settlements, pressures, and vibrations. The conclusion is that settlements of 1-3 feet were achieved without lateral dam movement, and explosive compaction was more cost effective than traditional excavate and replace methods.

1. 62nd Annual Meeting • 2005 • Peter Kiewit Sons’, Inc.

2. 62nd Annual Meeting • 2005 • Peter Kiewit Sons’, Inc.
Deep Ground Improvement
using
Explosive Compaction
Dario Gnoato - Western Canada

3. Presentation Outline
• Background on the Existing Dam
• Why the Need for Upgrading
• Explosive Compaction (EC)
• What is it?
• How does it Work?
• Explosive Compaction Program
• Panel Development
• Drilling and Casing the Holes
• Blasting
• Conclusion

4. Seymour Dam - Vancouver, BC
• Built in 1959
• Vancouver’s main
Water Reservoir
• Annual Rainfall
exceeds 189 inches
• 90ft high x 1300ft
Concrete Structure
• 90ft high x 1600ft
Earth Filled Structure
Zone to be
Improved
0 to 20ft Cut
& Fill
20 to 50ft
Dynamic
Compaction
50 to 80ft
Explosive
Compaction

5. What is Blast Densification?
“A Way to Densify the Ground Without Having
to Remove and Replace It”

6. How Does Blast Densification Work?
Blast
Charge
Drill Hole

7. Blast Densification Pressure Waves
• Compression &
Shear Stress Waves
Travel Through the
Granular Soil &
Water

8. Blast Densification Displacement
• Displaced Material
Settles to a Denser
Configuration

9. Explosive Compaction Program (EC)
Three Components
1. Development of EC Panels
2. Drilling & Casing the Blast Holes
3. Blasting the Holes

10. Explosive Compaction Panels

13. 1 Panel 1
Excavation: 22,100 yd3

14. 13
15
14
16
Panels 13 - 16
Excavation: 2,400 yd3

15. 23
Panels 2 - 3
Excavation: 45,600 yd3

16. 4
5
6 8
Panels 4 - 8
Excavation: 44,100 yd3

17. 9
Panel 9
Excavation: 1,900 yd3

18. 10
11
12
Panels 10 - 12
Excavation: 32,700 yd3

19. EC Earthworks
Basic Equipment
• 35ton Rock Trucks
• 345 Excavators
• D6 Dozers
• 148,000yd3 total
• Costs $2.90/yd3
(NIC maintenance)
• Production 150yd3/hr

20. EC Earthworks - Problems
• 35% of Native is 6yd3 +
boulders
• Largest to date 180yd3

21. EC Drilling and Casing
• 780 – 70ft x 6“
Cased Holes
• Water Tight 4“
PVC casing
Installed

22. EC Drilling Equipment
2 – Down the Hole Hammer
Reverse Circulation Drills
Production = 10ft/hr
= 0.27MHr/ft

23. EC Drilling Equipment
Symmetrix Drilling System
by Rotex
Modular Drilling System,
consists of:
1. Casing Shoe that is
Welded to the First
Casing
2. Ring Bit that Rotates
Freely on the Casing
Shoe
3. Pilot Bit that Locks to the
Ring Bit

24. EC Drilling Equipment

25. EC Charge Pattern
• 20 Drill Holes/Blast
• 4 Decks/Hole = 80
Decks/Blast
• 2400 lbs Explosive/
Blast
• 0.3 lbs/yd3 Powder
Factor
• Each Bench is
Blasted 3 Times
25ft
25ft
15ft
55ft
#4
#3
#2
#1 55lb
42lb
11lb
11lb

26. EC Blasting – Equipment
• Orika i-kon Digital
Detonators
• Timing from 1st to the 80th
Deck can Not Vary More
than 0.1%
• Totally Programmable
• 2-Way Communication with
Blast Control Equipment
• Delay Time 0-15,000ms with
1ms Increments
• Very Expensive - $45 vs $4
for standard Electric Type
Detonator

27. EC Blasting – Equipment
• Orica i-kon Logger
• Communicates with
Detonators
• Assigns the
Predetermined Time
Delay

28. EC Blasting – Equipment
• Orica i-kon Blaster
• Communicates with
Logger to Receive
the Blast Data
• Communicates with
Detonators for Final
Check of the Status
of all Detonators Prior
to Blast

29. EC Blasting – Material
1. Dyno Nobel IREMITE TX
• Cap Sensitive packaged
Explosive Emulsion
• Resistant to Dead
Pressing
• No Powder Headache
• Water Resistant
• Insensitive to Low
Temperatures
2. Dyno Nobel Pentolite Cast
Booster
• High Performance
• Insensitive to Freeze/
Thaw Cycles

30. EC Charge Loading Procedure
• Dewater PVC Casing
Pipe to Minimize
Hydraulic Shock
Effects on Explosive
Decks
• We Do Not want
Sympathetic
Detonation

31. EC Charge Loading Procedure
• Each Explosive Deck
is Primed Using an
i-kon Electronic
Detonator + Pentolite
Cast Booster
• Load Required
Charge Weight of
Iremite TX Explosive
into each Deck

32. EC Charge Loading Procedure
• Each Detonator is
Verified & the Firing
Time is Input using an
i-kon Logger
• Stemming Material is
Loaded into Blast
Hole

33. EC Charge Loading Procedure
• Once the Complete
Pattern has been loaded,
the Detonators are Wired
into Series Circuit using
i-kon specialized Clips &
Harness Wire
• The Complete Blasting
Circuit is Checked &
Verified Electronically
using the i-kon Logger
before Hook Up to the
i-kon Blaster

34. EC Blast Equipment

35. EC Blast

36. EC Data Monitoring
• 6 Seismographs situated throughout the site, these are
Used To Monitor Movements (Peak Particle Velocity)
Scaled Distance PPV vs. Rh/W
1/2
1.0
10.0
100.0
1000.0
1.0 10.0 100.0 1000.0
R/W^0.5 (m/kg^0.5)
MeasuredPPV(mm/s)
Pass 1 (measured)
Pass 2 (measured)
Pass 3 (measured)
Y=2500*X^(-1.5)
Y=4500*X^(-1.5)

37. EC Data Monitoring
• 18 Piezometers used to measure Pore Pressures
at the Toe of the Existing Dam (6 vibrating wire,
6 strain gauge & 6 pneumatic type)
Electric Piezometer DH04-2A(E) - Panel 9A - Pass 2
Layout 2, Blast on October 18, 2004 (16:42:55)
200
205
210
215
220
25 30 35 40 45 50 55 60 65
Time (seconds)
ElevationofWater(m)
DH04-2A(E)
Piezo. elev. 184.4 m
Time of Blast
18m = 59ft Water
Head Increase

38. EC Data Monitoring
• 9 Deep Settlement Posts
• Over 100 Survey Shots Pre & Post Blast
• Survey Monitoring of existing 84” diameter
Water Line that is 30yds from some of the Blasts
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
28-A
pr-04
28-M
ay-04
27-Jun-04
27-Jul-04
26-A
ug-04
25-S
ep-04
25-O
ct-04
Date
CumulativeChangeinElevation(m)
TMP-A TMP-B TMP-C TMP-D TMP-E TMP-F TMP-G TMP-H TMP-H2 TMP-I TMP-J TMP-K
TMP-L TMP-M TMP-N TMP - mg97 TMP - mg98 TMP - mg99 TMP-J1 TMP-J2 TMP-K1 TMP-K2 TMP-L1 TMP-L2
TMP-O TMP-P TMP-Q TMP-R TMP-S TMP-T
April May June July August Sept Oct
0.2m
0.1m
-0.1m
-0.2m

39. EC Data Monitoring
• Post Blast Standard
Penetration Tests in
order to Confirm
Compaction

40. Extensive Blast Confirmation
• High Speed Video Camera to Monitor the Nonel
Blast Tubes (80 tubes/blast)
• 80 Coaxial Cables/Blast, 1 per Deck
• 1 High Speed Piezometer (10,000 readings/sec)
• 1 Geophone set up at the Center of the Blast
Pattern to Record Transient Pressures
• 6 Seismographs

41. Conclusion
• Settlements are 1 to 3 ft
• Dam Toe has Not Moved
Laterally
• Owner Considers the
Program Very Successful
• Why Do It this Way?
• Excavate and Replace
$23.30/yd3
(NIC processing costs)
• Explosive Compaction
$9.10/yd3