WINTON WETLANDS COMMITTEE
OF MANAGEMENT
Memorandum
Date:
20/02/2015
File Ref.:
2015-01 A2
To:
All Tenderers
From:
Julie flack
Re:
Contract No. 2015-01, Construction of a Pedestrian Bridge
In response to enquiries raised in relation to the above contract, I wish to clarify the following
issues.
1
Preparation of steelwork for painting with zinc-in-silicate paint system?
The steelwork shall be prepared for painting or galvanizing in accordance with the specification –
Section 3.4 Steelwork. The specification requires that the steelwork is to be dry abrasive blasted
to remove all mill scale, rust, existing paint coating and foreign matter in order to meet the
requirements of VicRoads - ‘Standard Specifications for Roadworks and Bridgeworks’-Section 631
Protective Treatment of Steelwork.
2
Do the Upper and Lower rails require punching for welding the balustrade dowels?
The rails were designed with the upper and lower rails punched to allow for the dowels to be plug
welded to the railing; for the contractors convenience. The dowels may be welded directly to the
upper and lower rail without punching if desired.
3
How are the tops of piles to be prepared for painting?
The tops of piles extending above the ground were nominated for painting primarily to prevent the
crosshead galvanizing from being consumed by the corrosion of the pile. The specification
required that the tops of the piles to be painted were to be dry abrasive blasted to remove surface
defects. As the site is a sensitive environmental area, the contractor may prepare the piles by
wire brushing surface defects rather than using abrasive blasting.
4
How are the crossheads to be affixed if the piles are out of location?
The design allows for some deviation from the setout point. It was assumed that the contractor
would drill the bolt holes for the crosshead-pile connection on site which would allow the
connection to be located accurately on the pile flange. The crosshead was also extended to allow
for some deviation from the setout point. A shim would be permissible to ensure that the
crosshead was installed level.
5
Can a copy of the Geotechnical Information be supplied?
Attached is the geotechnical investigation for the site. The geotechnical report is attached on a
‘for information only’ basis as there are some differences between the report and the
plans/specifications. For instance, the report investigates the use of various piles which were not
used in the final design.
Julie Flack
Site Development Manager
Consulting Geotechnical Engineers
ACN 005 777 060
RURAL WORKS PTY LTD
WINTON WETLANDS COMMITTEE OF MANAGEMENT
WINTON WETLANDS BOARDWALK
LAKE MOKOAN ROAD, WINTON NORTH
GEOTECHNICAL INVESTIGATION
REPORT NO V1638RD
JUNE 2014
Black Geotechnical Pty Ltd
258 Hyde Street, Yarraville, Victoria, Australia 3013
Ph: 03 9689 0200 Fax: 03 9689 0155 [email protected]
web site: www.blackgeotechnical.com.au
Winton Wetlands Boardwalk
Report No V1638RD, June 2014
2
DOCUMENT INFORMATION
Document Version
version
date reviewed
RD
02/06/2014
reviewed by
NS
Distribution of Copies
version
electronic or hard copy
RD
Electronic
Last Saved:
Project Number:
Author:
Name of Client:
Name / Address of Project:
Document Version:
date issued
02/06/2014
date issued
02/06/2014
version description
First draft
issued to
Steven Cobden – Rural Works Pty Ltd
([email protected],.u)
Jim Grant – Winton Wetlands CEO
[email protected]
2 June 2014
V1638
George Black
Rural Works Pty Ltd
Winton Wetlands Boardwalk
RD
Note that report version is issued as a draft for client comments.
Black Geotechnical Pty Ltd
continued...
Winton Wetlands Boardwalk
Report No V1638RD, June 2014
3
CONTENTS
1.0 GENERAL ............................................................................................................................................... 4 1.1 Purpose of investigation .......................................................................................................................... 4 1.2 Proposed development ............................................................................................................................ 5 1.3 Existing conditions & access ................................................................................................................... 5 2.0 SUB-SURFACE CONDITIONS ............................................................................................................... 6 2.1 Reported geology .................................................................................................................................... 6 2.2 Fieldwork ................................................................................................................................................. 6 2.3 Sub-surface profile .................................................................................................................................. 6 3.0 DISCUSSION & RECOMMENDATIONS ................................................................................................ 7 3.1 Earthquake site sub-soil class ................................................................................................................. 7 3.2 Footing recommendations ....................................................................................................................... 7 3.3 Footing settlement ................................................................................................................................... 8 3.4 Footing testing ......................................................................................................................................... 8 3.5 Construction............................................................................................................................................. 8 3.6 Additional testing ..................................................................................................................................... 8 3.7 Validity ..................................................................................................................................................... 8 APPENDIX A ............................................................................................................................................... 10 Figure 1C CPT explanation sheet ............................................................................................................ 10 Plots CPT01, CPT02 & CPT03 ............................................................................................................. 10 Black Geotechnical Pty Ltd
continued...
Winton Wetlands Boardwalk
Report No V1638RD, June 2014
4
1.0 GENERAL
1.1 Purpose of investigation
This report presents the results of a geotechnical investigation performed for the proposed Winton
Wetland Boardwalk, off Lake Mokoan Road, Winton North. An approximate locality plan is shown below.
SITE
Black Geotechnical Pty Ltd
continued...
Winton Wetlands Boardwalk
Report No V1638RD, June 2014
5
GENERAL
Purpose of investigation
continued….
The purpose of the investigation was to:





Determine the sub-surface conditions at the site.
Provide an earthquake Site Sub-Soil Class in accordance with AS 1170.4 – 2007.
Provide recommendations for footing (pile) types, stiffness, founding depth & capacity (axial & lateral).
Provide settlement estimates.
Discuss construction.
1.2 Proposed development
It is understood it is proposed to construct an elevated long span boardwalk over a distance of about 600
m. The proposed elevated boardwalk is in an area where there are large bodies of low lying ground to
the north and south separated by narrow section between sand ridges to the east and west. It is
understood that the boardwalk on either side of the elevated section will be a short span low level structure
taking advantage of sand ridges.
It is understood that the elevated section of boardwalk will in places have a concrete deck and in places
have a timber deck. A single support is proposed at the abutment and pier positions leading to differing
axial loads (highest for the concrete deck) and differing moments (highest for the timber deck).
The maximum advised limit state loads are as follows:



Vertical load - 375 kN.
Maximum moment applied at pile head – 280 kNm.
Lateral load – 167 kNm.
It is understood that a UC pile is preferred because of the pile connection to the deck.
It is understood that it is proposed to use a local contractor to install the piles using a 30 tonne tracked
excavator that can drive a 10.5 m long section. It is understood that the underside of deck is 1.8 m above
the waterway invert level and the maximum length of pile in the ground that can be installed without
splicing is about 8 m.
1.3 Existing conditions & access
The site is within the area occupied by the decommissioned Lake Mokoan water storage. Previously,
when Lake Mokoan was at full supply level, it is understood that the proposed elevated boardwalk area
was under 5-6 m of water. Currently, the land on either side of the elevated boardwalk section is above
the wetland water level. It is understood that the water level has not, since the drought of the 2000s,
reached the storage level that could be attained with the level of the breach in the dam wall. When there
is sufficient inflow into the wetland, it is understood that the minimum water level in the wetland will be
about 600 mm. As noted above, the maximum depth of water at the elevated boardwalk site is about 1.8
m.
The site was inspected on 3 & 4 May 2014 and it was judged that the site would be accessible to a 4WD
ute and the proposed small track mounted investigation rig. The route of the elevated boardwalk was
mostly dry. The fieldwork was programed for 12 May and the proposed access route was via the existing
boat ramp and across the flats that skirt the existing water body. There was heavy rain on 10 May and an
inspection on 12 May indicated that the proposed access route was no longer suitable for a 4WD ute and
possibly not for the investigation rig. An alternative access route was found for the investigation rig via a
previously cleared route through a stand of dead trees that runs directly from the shore line to the
proposed elevated boardwalk. This is the route that will be taken by the low level section of the
boardwalk.
Once at the site of the elevated boardwalk, the site was observed to be under up to 200 mm of water and
the investigation rig operator was unwilling to track the rig across the area on the basis that if the rig
became bogged it would be a major operation to recover the rig. The investigation was therefore confined
to the west side of the elevated boardwalk section. As discussed in Section 2.1, it is considered that the
investigation sites will be representative of the conditions along the route of the elevated boardwalk and
that this should be confirmed at the time of construction when there will be better access.
Black Geotechnical Pty Ltd
continued...
Winton Wetlands Boardwalk
Report No V1638RD, June 2014
6
2.0 SUB-SURFACE CONDITIONS
2.1 Reported geology
The Geological Survey of Victoria, 1:250,000 Series, Wangaratta Sheet, suggests the site surface geology
is early Quaternary Period alluvium (Shepparton Formation). The Shepparton Formation is a deep
deposit of over-consolidated clay, with some sand, that has high strength.
The geological map shows the old Lake Mokoan water body with no interpretation of the geology below
the water but the image of the lake is surrounded by mostly Shepparton Formation.
The map shows Silurian Period granite further to the north and west of the lake and Ordovician Period
sedimentary rock further to the east.
2.2 Fieldwork
As discussed in Section 1.3, due to access the investigation was limited to the west end of the site where
three cone penetration tests (CPTs) were conducted to depths of 9.1 m to 12.8 m. CPT01 was terminated
at 11.6 m due to high end bearing resistance. CPT 02 and CPT 03 were terminated at depths of due 9.1
m and 12.8 m due to the rods flexing due to mostly to very high friction.
Plots of the CPTs are included in Appendix A. The plots show cone resistance, friction resistance, pore
pressures and friction resistance.
The test locations were recorded by GPS and are shown below. CPT01 was located close to a silt marker
(a 100 mm x 100 mm timber post) that is believed to be at about CH 650.
2.3 Sub-surface profile
The CPTs encountered relatively uniform sub-surface conditions consistent with the reported Shepparton
Formation alluvial deposits.
The CPTs encountered firm clay becoming stiff at about 1.5 m becoming very stiff to hard at about 5 m.
There is a change to probable sandy clay between 5 m and 7.5 m.
CPT01 & CPT03 encountered a 0.5 m to 1 m thick layer of dense sand at about 9 m. CPT02 may have
encountered refusal in this layer. Below the sand layer, CPT 01 and CPT 03 encountered hard clay to the
termination depths of 11.4 m in CPT 01 due to high end bearing and 12.8 m in CPT 03 due to
accumulated friction. No weak clay, except for the top 0.5 m, or so, was encountered in the cone
penetration tests.
The topography of the site is relatively flat. It is considered the site of the proposed elevated boardwalk is
within the Shepparton Formation and that the strength of the sub-surface along the route of the elevated
section of the proposed boardwalk is unlikely to be less than the strength encountered in three CPTs.
This is discussed in Section 3.6.
Black Geotechnical Pty Ltd
continued...
Winton Wetlands Boardwalk
Report No V1638RD, June 2014
7
3.0 DISCUSSION & RECOMMENDATIONS
3.1 Earthquake site sub-soil class
The Earthquake Site Sub-Soil Class in accordance with AS 1170.4-2007, Structural design actions, Part
4: Earthquake actions in Australia, Section 4, is judged to be Class De due to the deep deposit of alluvial
sediments.
The Hazard Factor (Z) in accordance with AS 1170.4 – 2007 is 0.9.
3.2 Footing recommendations
Driven piles will achieve their capacity from mostly shaft adhesion with some contribution from end
bearing. The sand layer at about 9 m is not thick enough to be a pile end bearing layer.
Driven steel UC piles and CHS piles have been considered.
With a CHS pile, shaft adhesion can be applied over the external surface area of the section and end
bearing can be applied to the full area of the base.
With a UC pile, shaft adhesion can only be applied over the external flange area. End bearing can be
applied to the full area of the base. The reason for this is that as the section is driven, a plug will generally
form over the lower part of the pile and above this plug the soil adjacent to the inside flange and the web
is disturbed and cannot be relied upon. Over the length of the plug, shaft adhesion is contributed by the
external flange and the sides of the soil plug between the flanges. The length of the plug is not known
and cannot be physically measured. However, the effect of the plug can be determined by pile testing
(PDA tests).
Three driven steel pile sections have been considered. These are a 310 UC, a 337 CHS and a 424 CHS.
The design geotechnical strength capacities for a pile section with an 8 m embedment are shown in Table
3.2.1. The top 1 m of the pile is assumed not to contribute to pile capacity. There is a second row for the
310 UC, which assumes a plug develops over the lower 3 m of the pile. Table 3.2.1 also shows the ratio
of moments resisting and causing overturning and the maximum moment in the pile due to the applied
moment and the lateral load. The table also shows the pile length required to achieve the design limit
state vertical load. Moment capacity has been assessed using the Brinch-Hansen method.
Table 3.2.1. Pile capacities and lengths
DGS capacity of pile with 8 m
embedment, kN
Pile section
Shaft
End
Total
adhesion
bearing
310 UC no
115
110
225
plug
310 UC 3 m
165
110
275
plug at base
337 CHs
195
100
295
424 CHS
245
155
400
Moment capacity of pile with
8 m embedment
Max moment
Moment ratio
in pile, kNm
embedment
for
375 kN, m
5.5
700
16.5*
5.5
700
11
6.25
7.7
700
685
9
7
Table 3.2.1 indicates that the only pile that will achieve the required design geotechnical strength capacity
of 375 kN, based on static soil mechanics, with an embedment of 8 m, is a 424 mm CHS section.
Actual pile capacity is often greater than that predicted by static soil mechanics. It is very likely that, on
test, a 337 CHS section will achieve the required capacity.
*It is considered likely that the 310 UC (no plug) will achieve the design limit load at about 12 m due to
increasing strength at depth indicated by CPT01 and CPT03.
The two best options appear to be:

A 310 UC with 12 m embedment and with a splice (the first pile should be PDA tested at the time of
driving to determine if the splice is required).

A 337 CHS with an 8 m embedment (also PDA tested while driving).
Black Geotechnical Pty Ltd
continued...
Winton Wetlands Boardwalk
Report No V1638RD, June 2014
DISCUSSION & RECOMMENDATIONS
8
continued…
3.3 Footing settlement
The theoretical maximum post construction settlement of any of the proposed driven piles due to ground
compression is less than 5 mm.
3.4 Footing testing
PDA tests should be performed on at least of 15% of the piles.
The remaining pile capacities should be confirmed by driving to a minimum set and energy determined by
CAPWAP analysis.
If piles are adopted that require a higher capacity than that predicted by static soil mechanics, the piles
should be PDA tested while driving. If the piles initially fail, they should be re-tested after 24 hours when
they will most likely pass due to set-up caused by the dissipation of excess pore pressures generated by
the driving.
The design geotechnical pile capacity should be determined using the reduction factors contained in
VicRoads BTN 1996/001.
The geotechnical strength reduction factors for the testing of ‘representative’ and ‘represented’ piles are
indicated below in Table 3.4.1 (assuming the ‘representative’ piles are PDA tested and analysed using
CAPWAP).
Table 3.4.1. Geotechnical Reduction Factors for Pile Testing
pile type
geotechnical strength reduction factor, ɸg
Representative (tested)
0.8
Represented (not tested)
0.7
The approximate pile capacity can be assessed by the Hiley Formula as installation proceeds. Details
can be provide when pile capacity, hammer size and drop are known.
3.5 Construction
Unless the subgrade significantly dries out it will be necessary to construct a road to and along the route
of the elevated boardwalk section to provide access for the pile driving rig and equipment trucks.
As a minimum, it is considered that in the elevated boardwalk area this will require a 750 mm, or so, of
gravel layer placed in a single layer to bridge the weak surface soil. The surface of the single layer should
be compacted to about 95 % standard.
3.6 Additional testing
As noted previously, it was only possible to access the west end of the proposed elevated boardwalk
route. Whilst, it is considered likely that the strength of the sub-surface along the route of the elevated
boardwalk will be similar to that encountered in the three cone penetration tests, this should be confirmed
by additional cone penetration tests along the route.
When the access road recommended in Section 3.5 is constructed, it is recommended that additional
CPTs are conducted along the route of the elevated boardwalk to confirm the findings of this investigation.
3.7 Validity
If sub-surface conditions different from those described above are encountered during construction the
recommendations contained in this report may not be valid and the company should be contacted.
The report recommendations should not be applied to any development other than that described in
Section 1.2 without reference to the company.
Black Geotechnical Pty Ltd
continued...
Winton Wetlands Boardwalk
Report No V1638RD, June 2014
9
BLACK GEOTECHNICAL PTY LTD
Black Geotechnical Pty Ltd
continued...
Winton Wetlands Boardwalk
Report No V1638RD, June 2014
10
APPENDIX A
Figure 1C
Plots
Black Geotechnical Pty Ltd
CPT explanation sheet
CPT01, CPT02 & CPT03
continued...
FIG. 1C
Consulting Geotechnical Engineers
ACN 005 777 060
DESCRIPTION OF CONE PENETRATION TEST
A Cone Penetration Test involves using hydraulic rams to push 36mm diameter rods into the soil from within a
ballasted truck or drill rig. Attached to the end of the rods is a cone containing various strain gauges which
measure the geotechnical properties of the soil as the cone is pushed into the ground. Measurements are taken
every centimetre. In general, three different cones can be used in a CPT investigation.
Standard Friction Cones provide qc (tip resistance), fs (sleeve friction) and inclination. The qc is used to
determine the strength of the soil. Using qc and fs together allows the determination of the friction ratio, Rf (= fs/
qc x 100%), which helps identify soil type. Measuring inclination allows the operator to determine if the cone is
being bent in the soil, and therefore prevents damage. Plots are also corrected for deviation from vertical. A
15cm cone can be used where adverse soil conditions are expected.
Piezocones incorporate a pore-pressure sensor (u2), along with qc, fs and
inclination, allowing highly accurate identification of very thin soil layers and
differentiation between similar soil types; qc is corrected for pore-pressure
effects to provide qt. Piezocones also enable dissipation testing, where the
dissipation of excess pore pressures is measured to estimate parameters for
coefficient of consolidation and rough estimates of permeability.
qt
fs
u2
Rf
Example of a piezocone and how the data obtained is presented.
qc
u2
fs
data connection
Mechanical Cones provide qc only, however, Example of a mechanical cone.
they are very robust and are useful for testing
in adverse conditions such as detecting voids
within cemented sands, probing extremely
weathered rock profiles or for use in areas of
CPT Soil Behaviour Type chart.
fill of unknown composition.
Whichever type of cone is used, all data is logged
electronically via on board computer systems within each truck.
Interpreting the soil type in the field is possible using this soil behaviour
type chart from Robertson et al., 1986, by comparing cone resistance
(qc) against friction ratio (Rf = fs/qc x 100). More accurate determination
of soil type is possible by using normalized data after the fieldwork is
complete.
BIT’s 6x6 DAF CPT rig.
Black Geotechnical Pty Ltd
258 Hyde Street, Yarraville, Victoria, Australia 3013
Ph: 03 9689 0200 Fax: - 03 9689 0155 - Email: [email protected]
web site: www.blackgeotechnical.com.au
qt in MPa
0
0
5
Sleeve f riction (f s) in MPa
10
15
20 0
0.1
0.2
0.3
u2 in MPa
0.4 -0.2
0
Friction ratio (Rf ) in %
0.2
0.4
0.6 0
2
4
6
8
-0.5
<- Depth in m to reference level / corrected for inclination
-1
-1.5
-2
-2.5
-3
-3.5
-4
-4.5
-5
-5.5
-6
-6.5
-7
-7.5
-8
-8.5
-9
-9.5
-10
-10.5
-11
u2
CPTask V1.33
150
10
Client: Black Geotechnical
cm²
cm²
G.L. 0
W.L.: 0
Project:
Winton Wetlands Boardwalk
Location: Winton North
Position:
Predrill :
0
Date:
5/12/2014
Cone no.:
C10CFIIP.C11073
Project no.:
D127
CPT no.:
CPT_01
1/2
qt in MPa
-11
0
5
Sleeve f riction (f s) in MPa
10
15
20 0
0.1
0.2
0.3
u2 in MPa
0.4 -0.2
0
Friction ratio (Rf ) in %
0.2
0.4
0.6 0
2
4
6
8
-11.5
<- Depth in m to reference level / corrected for inclination
-12
-12.5
-13
-13.5
-14
-14.5
-15
-15.5
-16
-16.5
-17
-17.5
-18
-18.5
-19
-19.5
-20
-20.5
-21
-21.5
-22
Test Complete at 11.64m qc > 20MPa
Pushing 12 ton Hole closed at 0.3m
u2
CPTask V1.33
150
10
Client: Black Geotechnical
cm²
cm²
G.L. 0
W.L.: 0
Project:
Winton Wetlands Boardwalk
Location: Winton North
Position:
Predrill :
0
Date:
5/12/2014
Cone no.:
C10CFIIP.C11073
Project no.:
D127
CPT no.:
CPT_01
2/2
qt in MPa
0
0
5
Sleeve f riction (f s) in MPa
10
15
20 0
0.1
0.2
0.3
u2 in MPa
0.4 -0.2
0
Friction ratio (Rf ) in %
0.2
0.4
0.6 0
2
4
6
8
-0.5
<- Depth in m to reference level / corrected for inclination
-1
-1.5
-2
-2.5
-3
-3.5
-4
-4.5
-5
-5.5
-6
-6.5
-7
-7.5
-8
-8.5
-9
-9.5
-10
-10.5
-11
Ref usal at 9.1m Rods f lexing
Hole closed at 9.1m dry
u2
CPTask V1.33
150
10
Client: Black Geotechnical
cm²
cm²
G.L. 0
W.L.: 0
Project:
Winton Wetlands Boardwalk
Location: Lake Mokoan Road Winton North
Position:
Predrill :
0
Date:
5/13/2014
Cone no.:
C10CFIIP.C11073
Project no.:
D127
CPT no.:
CPT_02
1/1
qt in MPa
0
0
5
Sleeve f riction (f s) in MPa
10
15
20 0
0.1
0.2
0.3
u2 in MPa
0.4 -0.2
0
Friction ratio (Rf ) in %
0.2
0.4
0.6 0
2
4
6
8
-0.5
<- Depth in m to reference level / corrected for inclination
-1
-1.5
-2
-2.5
-3
-3.5
-4
-4.5
-5
-5.5
-6
-6.5
-7
-7.5
-8
-8.5
-9
-9.5
-10
-10.5
-11
u2
CPTask V1.33
150
10
Client: Black Geotechnical
cm²
cm²
G.L. 0
W.L.: -9.4
Project:
Winton Wetlands Boardwalk
Location: Lake Mokoan Road Winton North
Position:
Predrill :
0
Date:
5/13/2014
Cone no.:
C10CFIIP.C11073
Project no.:
D127
CPT no.:
CPT_03
1/2
qt in MPa
-11
0
5
Sleeve f riction (f s) in MPa
10
15
20 0
0.1
0.2
0.3
u2 in MPa
0.4 -0.2
0
Friction ratio (Rf ) in %
0.2
0.4
0.6 0
2
4
6
8
-11.5
<- Depth in m to reference level / corrected for inclination
-12
1.6754 ->
1.5255 ->
-12.5
1.7238 ->
-13
-13.5
-14
-14.5
-15
-15.5
-16
-16.5
-17
-17.5
-18
-18.5
-19
-19.5
-20
-20.5
-21
-21.5
-22
Ref usal at 12.81m Rods f lexing
Hole closed at 12.4m w et at 9.4m
u2
CPTask V1.33
150
10
Client: Black Geotechnical
cm²
cm²
G.L. 0
W.L.: -9.4
Project:
Winton Wetlands Boardwalk
Location: Lake Mokoan Road Winton North
Position:
Predrill :
0
Date:
5/13/2014
Cone no.:
C10CFIIP.C11073
Project no.:
D127
CPT no.:
CPT_03
2/2