control of groundwater to excavations: barriers and … › wp-content › uploads › 2018 › 06...
TRANSCRIPT
![Page 1: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/1.jpg)
Control of groundwater to excavations:
Barriers and dewateringPresented to IAH – NSW Branch
June 2018
![Page 2: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/2.jpg)
Control of groundwater to excavationsContent
Purpose
Control Methods
Assessment Tools
Empirical
Analytical
Semi-analytical
Numerical
Examples
References
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
2
![Page 3: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/3.jpg)
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
3
01Purpose
![Page 4: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/4.jpg)
Control of groundwater to excavationsPurpose
Why control groundwater to excavations?
Design
• Make inflows/levels more predictable
Construction
• Make the site more manageable
• Reduce treatment volume
• Reduce impacts
Operation
• Reduce on-going cost of pumping/treatment
• Comply with regulatory requirements
• Reduce impacts
• Reduce risk from contamination
Typical introduction to groundwater dewatering
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
4
![Page 5: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/5.jpg)
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
5
02Control methods
![Page 6: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/6.jpg)
Control of groundwater to excavationsControl methods - Barriers
Diaphragm Wall
• Panel construction under bentonite, full reo cage
• Excellent control, Seepage: anchor penetrations & base
Secant pile
• Overlapping piles (hard/soft), reo cage in half piles
• Good control, Limited depth – gaps from splay
Cutter Soil Mix
• Installed in panels like D Wall, soil mixed with cement
• Reinforcement limited to I beams
Jet grout
• Spinning jet cuts and mixed soil with grout
• Can provide good control – typically temporary
• Can be used with secant pile/contiguous piles
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
6
![Page 7: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/7.jpg)
Control of groundwater to excavationsControl methods - Barriers
Soil mix wall
• Soil mixed with bentonite in trench
• Low permeability, non structural
• Control of groundwater flow only
Sheet pile walls
• Interlocking steel sheets
• Typically temporary, sheets reusable
• Vibration during installation can be problematic
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
7
![Page 8: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/8.jpg)
Control of groundwater to excavationsControl methods – Recharge / Extraction
Recharge wells and trenches
• Recharge of clean water to prevent adverse impacts
• Harder to get water into the ground
Extraction wells – capture contaminated water
• Pumping downgradient to capture contaminated
groundwater
• Need to assess existing gradient and flow rate
• Extract at a rate equal to width time the flow rate
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
8
![Page 9: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/9.jpg)
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
9
03Tools
![Page 10: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/10.jpg)
Control of groundwater to excavations - ToolsMaking predictions
Analysis methods
• Empirical
• Analytical
• Semi-analytical
• Numerical
Finite element / finite difference / boundary element
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
10
![Page 11: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/11.jpg)
Control of groundwater to excavations - ToolsMaking predictions
Illustrative section – things of interest
• Flow (q)
• Drawdown (h)
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
11
Q
q
x
h1 h2
Permeability k
![Page 12: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/12.jpg)
Control of groundwater to excavations - ToolsMaking predictions – Flow beneath wall
Flow beneath cut off wall
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
12
Q
q
x
h1 h2
Permeability k
h
![Page 13: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/13.jpg)
Control of groundwater to excavations - ToolsMaking predictions
Flow beneath a wall (Harr 1962 after Polubarinova-Kochina 1952)
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
13
0.25
0.5
0.75
1.0 1.25
1 5
h
b b
s
T
Drawdown h = 12 m Penetration s = 2 m Rock permeability k = 0.01 m/d Rock thickness T = 16 ms/T = 0.125 -> q/kh = 0.95
q = 0.95 x 0.01 m/d 12 m = 0.114 m3/d/m
![Page 14: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/14.jpg)
Control of groundwater to excavations - ToolsFlow beneath cut off wall
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
14
Further useful result
𝜀
![Page 15: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/15.jpg)
Control of groundwater to excavations - ToolsFlow beneath cut off wall
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
15
Further useful result – excavation of limited width (trenches) - Harr 1962
![Page 16: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/16.jpg)
Control of groundwater to excavations - ToolsMaking predictions
Extent of drawdown – Extensive aquifer
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
16
Q
q
x
h1 h2
B
Specific yield Sy
h
Transmissivity (T)
Vertical permeabilty (kv)
Storativity (S)
![Page 17: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/17.jpg)
Control of groundwater to excavations - ToolsMaking predictions
Extent of drawdown – Extensive aquifer (delayed yield –Kruseman and de Ridder (1991) (after Neuman)
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
17
![Page 18: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/18.jpg)
Control of groundwater to excavations - ToolsMaking predictions
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
18
Hunt (2012) provides spreadsheet tools
![Page 19: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/19.jpg)
Control of groundwater to excavations - ToolsMaking predictions
Drawdown extent – recharge balances extraction
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
19
![Page 20: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/20.jpg)
Control of groundwater to excavations - ToolsRecharge design
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
20
Example – Cut off wall
Trapezoidal shape (about 60 m x 60 m)
Permeable horizon underlain by rock
![Page 21: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/21.jpg)
Control of groundwater to excavations - ToolsRecharge design
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
21
Example – Cut off wall
Step 1 – Calculate seepage below wall
Step 2 – Integrate aquifer solution per wall
![Page 22: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/22.jpg)
Control of groundwater to excavations - ToolsRecharge design
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
22
Example – Cut off wall
Step 1 – Calculate seepage below wall
Step 2 – Integrate aquifer solution per wall
Step 3 – Combine for all walls
![Page 23: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/23.jpg)
Control of groundwater to excavations - ToolsRecharge design
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
23
Example – Cut off wall
Step 1 – Calculate seepage below wall
Step 2 – Integrate aquifer solution per wall
Step 3 – Combine for all walls
Step 4 – Include recharge wells
Excel spreadsheet contains the results
Alternate layouts can be tested
Note with recharge the effects are localisedand the nature of the aquifer more widely does not affect the outcome.
![Page 24: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/24.jpg)
Control of groundwater to excavations - ToolsNumerical methods
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
24
Use where analytical methods are too crude
Complex profiles
Free surface problems (drained walls)
Regional impacts
![Page 25: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/25.jpg)
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
25
04Examples
Northside storage tunnel – grouting control
Tempe – soil mix wall
Barangaroo Stage 1A – diaphragm wall
![Page 26: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/26.jpg)
Northside Storage Tunnel
![Page 27: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/27.jpg)
NST Background
Sydney Water Project - Collects four main sewer overflows
15.8km from Lane Cove River to North Head STW
Tunnel invert RL-43m to RL-96.5m
Northern branch tunnel 3.7km long to Scotts Ck. Tunnelling by
four TBMs (3.8m to 6.6m dia.)
Tunnel unlined
Project completed before the 2000 Olympics
![Page 28: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/28.jpg)
NST – Long Section
![Page 29: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/29.jpg)
Northside storage tunnel - Middle Harbour - Clontarf
![Page 30: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/30.jpg)
Middle Harbour Long Section
Middle HarbourMiddle HarbourClontarf Reserve
Sediments
Hawkesbury Sandstone
![Page 31: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/31.jpg)
NS 35-OB1 Drawdown - Trial
0mm
6mm
Settlement
Drawdown
Pumping
5L/s 8L/s0m
10m
![Page 32: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/32.jpg)
Grouting at Clontarf
Probe ahead grouting
Annular patterns of up to 56 holes
Grout take 3.75kg/uL/m
180t cement
Advance slowed from 225m/week to 5m/week (one month for
worst 25m)
Inflow limited to 18L/s
Permeability controlled to 1uL
![Page 33: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/33.jpg)
![Page 34: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/34.jpg)
Northside Storage Tunnel – Clontarf
-25
-20
-15
-10
-5
0
01-Jan-00 01-Jul-00 01-Jan-01 01-Jul-01 01-Jan-02 01-Jul-02 01-Jan-03 01-Jul-03 01-Jan-04 01-Jul-04 01-Jan-05
Date
NS
48
Gro
un
dw
ater
Lev
el (
mA
HD
)
-100
-80
-60
-40
-20
0
Set
tlem
ent
(mm
)
Groundw ater Lev el
SettlementTunnelling with Grouting
Ahead of Face
April to June 2000
Post tunnel
grouting
Spikes in groundwater level due to
surcharge (filling) events
100mm
0mm
25m
0mS
ettle
ment
Dra
wdow
n
Surcharge Events
Grouting after construction
Jan 2000Date Jan 2005
![Page 35: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/35.jpg)
Control of groundwater to excavationsNorthside Storage Tunnel
- No numerical modelling – evaluation carried out by direct extrapolation from
measurement and simple hand calculation
- Demonstrated construction without grouting control would result in very high inflow
(> 100 L/s) and cause settlement of piled syphon
- Grouting proved effective though time consuming
- Early waring allowed rescheduling of other operations to avoid delay to overall
program
- Ground – tightened up with time
- Monitoring proved a useful tool to evaluate performance during construction and
during operation
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
35
![Page 36: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/36.jpg)
Control of groundwater to excavationsTempe landfill remediation
Tempe Landfill
- Operated from early 1900’s
- Up to 17 m fill underlain by
alluvial/residual soils and sandstone
- Leachate entering Alexandria Canal
- 1.6 km soil/bentonite wall and drain
- Used long reach excavator (20 m)
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
36
![Page 37: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/37.jpg)
Control of groundwater to excavationsTempe landfill barrier
Soil mix wall
• Wall performance tested by closed cell – not conclusive
• Alexandria Canal tidal
• During construction monitoring assess performance
• Series of wells either side of alignment
• Monitoring demonstrated stopping of tidal response and raised
groundwater level
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
37
![Page 38: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/38.jpg)
Control of groundwater to excavationsBarangaroo Stage 1A
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
38
![Page 39: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/39.jpg)
Control of groundwater to excavationsBarangaroo Stage 1A
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
39
![Page 40: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/40.jpg)
Control of groundwater to excavationsBarangaroo Stage 1A – Ground conditions
• Site contained deep fill (highly transmissive) over alluvium and a sloping rock profile
• Rock profile contained buried cliff lines
• Diaphragm wall constructed to allow excavation 8 m below sea level
• Wall needed to reach rock at depth of up to 30 m
• Tanked structure with tie down piles a thick base slab connected to the diaphragm wall
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
40
![Page 41: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/41.jpg)
Control of groundwater to excavationsBarangaroo Stage 1A – Ground conditions
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
41
![Page 42: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/42.jpg)
Control of groundwater to excavationsBarangaroo Stage 1A – Ground conditions
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
42
• Constructed by Menard Bachy
• 700 m long diaphragm wall (6 m x 1 m panels) up to about 30 m deep
performed very well
• Anchors installed above sea level to reduce seepage
• Construction inflows less than 3 L/s (beneath the wall)
![Page 43: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/43.jpg)
Control of groundwater to excavationsBarangaroo Stage 1A – Ground conditions
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
43
• Monitoring of piezometers during wall construction
• Full tidal response 40 m back from the water of Darling Harbour
• Tidal response inside the wall dropped dramatically as D wall
panels near monitoring bores were completed
![Page 44: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/44.jpg)
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
44
05Closing
![Page 45: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/45.jpg)
Control of groundwater to excavationsClosing
Comments
• Various proven groundwater control methods available
• Barrier methods are mature
• Assessment methods revolve around flow estimation and
assessment of impact
– Best to extrapolate for local experience
– Analytical methods quite satisfactory
– Semi-analytical methods can address more complex
situations
– Numerical methods
• Examples
– Monitoring valuable to evaluate performance
Paraphrasing the great John Booker
Use simple hand calculations where possible
If necessary use analytical or semi-analytical methods
If desperate use numerical methods
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
45
![Page 46: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/46.jpg)
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
46
06References
![Page 47: Control of groundwater to excavations: Barriers and … › wp-content › uploads › 2018 › 06 › IAH...Control of groundwater to excavations : Barriers and dewatering A presentation](https://reader033.vdocument.in/reader033/viewer/2022060423/5f19d2f394aa5751bf55a9ea/html5/thumbnails/47.jpg)
Control of groundwater to excavationsReferences
• Boulton, N.S. (1963) Analysis of data from non-equilibrium pumping tests allowing for delayed yield from
storage. Proc. Inst. Civil Eng., 26, Paper No. 6693: 469-482.
• Edelman, J.H. (1972) Groundwater Hydraulics of Extensive Aquifers, International Institute of Land
Reclamation and Improvement, Wageningen, The Netherlands.
• Hantush, M.S. (1967) Flow to wells in aquifers separated by a semipervious layer. Journal of
Geophysical Research, 72(6), 1709-1720.
• Harr, M.E. (1962) Groundwater and seepage, McGraw-Hill.
• Huisman, L. (1972) Groundwater recovery, Macmillan.
• Hunt, B. (2012) Groundwater analysis using Function.xls, Civil Engineering Department, University of
Canterbury.
• Kruseman, G.P. and N.A. DeRidder 1979. Analysis and evaluation of pumping test data. International
Institute for Land Reclamation and Improvement, Wageningen , The Netherlands.
• Polubarinova-Kochina (1952) Theory of groundwater motion. Gostakhizdat, Moscow, 1952.
• Theis, C.V. (1935) The relation between the lowering of the piezometric surface and the rate and
duration of discharge of a well using ground-water storage. Trans. Am. Geophys. Union, 16: 519-524.
• Verruijt, A. (1970) Theory of groundwater flow, Mcmillan.
12 June 2018Control of groundwater to excavations : Barriers and dewatering A presentation to IAH – NSW Branch
47