Attachment B Eng report

Page 2

1.0

2.0

3.0

4.0

5.0

6.0

Table of Contents

Summary
Introduction
Project Description

3.1. Scope

3.2 General

3.3. Site Cond itions

3.4 Construction Management Plan

3.5 Construction of Retaining Walls and Excavation

Design Loading Criteria

4.1. General

4.2 Codes and Specifications
4.3. Loading Criteria

4.4 Deflection Criteria

Materials Specification

5.1. Concrete

5.2 Reinforcing Steel
5.3. Formwork

5.4 — Structural Steel
5.5 Screw Piling

Structural Framing System
6.1 General Structural System

6.2 Lateral Resistance
6.3 Drainage

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Appendix MCU Tod Consulting Engineers Drawing List

1.0

14517-— OPO1 General Notes
OP02 General Notes
OP03 Site Plan
OP04 Site Temporary Access and PilingPlan
OP05 Site Construction Works ,Stage 1-3
OPO06 Site Construction Works ,Stage 4-7
OP07 Building Sections
OP08 Construction Details Sheet 1
OPO9 Construction Details Sheet 2
0OP010 Earthworks —Cut Plan

Summary

The proposed residence at 71 Seaview Terrace, Sunshine Beach
comprises the following:

° Generally three living levels
° Access driveway at road /roof level, ramping down to garage level
e External terraced areas, pool and access corridors, stairs and lift

The Structural design of the project will consider the steep sandy nature of
the site and will be carried out in accordance with the relevant Australian
Standard Codes of Practice including but not limited to the following:

e AS/NZS 1170 Part 1 Loading Code: Dead and Live
° AS/NZS 1170 Part 2 Loading Code : Wind

e AS/NZS 1170 Part 4 Loading Code : Earthquakes
° AS2159 Piling Code

° AS 3600 Concrete Structures

° AS 3700 Masonry Code

e AS 4100 Steel Structures

e AS2783 Swimming Pool Code

° Building Code of Australia

The maximum loading deflection criteria to be adopted for the
development is as follows:

a) Horizontal (Lateral) movement (wind and seismic)
Total not greater than Height/500 (at maximum permissible stress
loads)
Inter-storey not greater than Floor to Floor Height/500 (at maximum
permissible stress loads)
b) Horizontal (lateral) movement of retaining walls due to horizontal
loads from retained soil and surcharge — not to exceed height/500.
Cc) Vertical movement (dead plus live load)

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2.0

Slab and beams are to be designed to achieve the following
maximum
deflection criteria

Incremental Deflection
General Span/500 or 15mm (whichever is less)

Long Term Deflection
Slabs Span/500 or 15mm (whichever is less)
Beams Span/500 or 15mm (whichever is less)
Spandrel Beams — Span/500 or 15mm (whichever is less)

Total allowable 20mm max to end spans
(Slab + Beam) 20mm to internal spans
Cantilever Span/250 or 10mm (whichever is less)

The structural framing system is to comprise a reinforced concrete frame
utilising permanent reinforced concrete slabs, beams and columns.
External decks and the garage floors are to be 40 MPa reinforced
concrete slabs and beams. All piled footings are to be founded into very
dense sands, stiff sandy clays or extremely weathered sandstone, at least
5m below any 27° sand slip line projected from the base of the slope, and
at least 7m below existing ground line, whichever is deeper. In some
localised areas, piled footings may need to be founded deeper than these
levels depending on excavation depth / sequence and pile loads.

Introduction

The following design criteria details the required structural performance
criteria for the proposed residence. It establishes the overall structural
performance requirements along with a series of minimum standards for
specific design and construction technical controls of the works.

Reference Documentation:

e Site Survey Drawings by Lawrence & Partners
e Noel Robinson Architectural Drawings dated 23.5.2014
81.269.B13 -
Sk 03.01 Rev. P1
Sk 03.02
Sk 03.03

Sk 05.01
Sk 05.02
Sk 05.03
Sk 05.04
Sk 05.05
Sk 05.06
Sk 05.07
Sk 05.08
Sk 05.09
Sk 05.10

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Geotechnical Report by SCG dated 24.3.2009, and Morrison
Geotechnical Report dated October 2014 , job no. DE 14/231

3.0 Project Description

3.1

3.2

3.3

Scope

The work covers the entire main house building structure including
but not limited to contiguous CFA (Continuous Flight Auger)
concrete piles and both vertical and raked concrete-filled
galvanised screw steel piled footings, slabs on ground, retaining
walls, external pavements, structural steel supports for claddings,
reinforced block walls, suspended reinforced concrete floors, roofs,
walkways, stairs and other minor structural items.

A significant component of the project is staged the construction of
the contiguous piled retaining structures which form part of the
permanent structure.

Cantilevered reinforced concrete contiguous piled walls are utilised
throughout the building works to provide a completely stable
building platform during all the construction stages, and these will
also greatly enhance the completed building’s capacity to resist
lateral loads and add significantly to the stability of all areas uphill
of the proposed works by limiting the extent of any future surface
sand slips.

Once the contiguous piled walls are completed and fully tied back
to each other via a system of ground beams and floor slabs at the
three main floor levels, the remainder of the structure can be
readily constructed on a safe and stable building platform using
traditional blockwork and floor formwork methods.

General
The proposed residence comprises the following:

° Three living levels to the main residence
e Access driveway at road/roof level.
° External terraced areas, pool and access corridors

Site Conditions

The information discussed below has been interpreted from the
geotechnical reports by Morrison Geotechnical (dated September
2009) and SCG Consulting Engineers dated 24 March 2009.

In brief, boreholes drilled across the site encountered fairly
consistent upper layer conditions comprising loose sands gradually
increasing in density with depth. Deeper surface conditions vary

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3.4

across the site from dense sands to very stiff sandy clays overlying
extremely weathered sandstone at approximately RL33.

Ground water seepage and springs are likely to be encountered at
any hard impermeable layers following wet weather.

Due to the topography of the site all precautions must be taken to
minimise risk of surface sand slips and possible flow of loose
surface sands from excavated trenches and building platforms.

The existing surface sands are very loose and slope at gradients of
between 23° and 32°.

The additional Geotechnical information provided in the Morrison
Geotechnical Report to 22.4m depth will be used to further develop
the structural design, and refine construction procedures.

Preliminary assessment indicates extremely weathered rock at
approx RL33.3, which will significantly reduce the risk of slope
instability and provide massive horizontal restraint to retaining
walls.

The loose surface sands are very prone to erosion and slippage,
particularly where vegetation is disturbed or removed, or
stormwater becomes concentrated.

Construction Management Plan

The site is located at the northern end of a sealed access driveway
off Seaview Tce, with no off-site parking and set down areas for
construction equipment. The size of vehicles accessing the site is
limited by the width and layout of the common driveway.

The Contractor will face various challenges on this project due to
the limited access, however it is clear that local Builders have had
sufficient experience with these types of sites eg, at the adjacent
homes in Seaview Tce; the recent construction of Mr Pat Rafter’s
house at 48 Seaview Tce; and current construction along Park Rd,
Noosa.

We suggest that the site is sufficiently large to accommodate all
construction vehicles and equipment/materials storage, providing
the Contractor plans his work carefully, and builds staged
temporary access ramp/platforms similar to our layout on Tod
Consulting drawing 14517-P4.

During the initial piling stage of the project there will be very few
subcontractors (Piling Contractor and part-time Surveyor) on site
and therefore “Stage 1 Temporary Access Area” of about 700m?
indicated on Drawing 14517-P4 should be adequate for all access,

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parking and storage. Total number of cars on site would be less
than five.

Once the contiguous piling is completed, screw piling will be
completed over the site and again there would be few other
Subcontractors involved in the works that time. (Piling Contractor
and Part-time Surveyor)

By this stage the Contractor should have extended his temporary
access/parking/storage platform across to the northern area of the
building, “Stage 2 Temporary Access Area” indicated on 14517 —
P4, greatly increasing parking, access and storage for materials.
Total number of cars on site would not exceed 10. During this time
there would still only be about 4-5 different subcontractors on site:-

Concretor/formworker

Reinforcing fixing

Plumber / Electrician ( both part-time)
Surveyor (part-time)

By the time the builder is constructing the floor slabs, we would
expect the number of subcontractors will increase up to
approximately 10 occasionally, but the accessible area for parking
and storage will be greatly increased, to include some areas of the
permanent structural driveway slab, probably exceeding 1500m?.

The successful Contractor will be required to provide, as a
contractural condition of the building approval, a detailed
Construction Management Plan appropriate for this site and the
extent of piling, excavation and concreting work. The Plan shall
cover the following issues:-

e Pre-construction

Submit a programme, construction method statements, traffic &
parking management plan, environmental and erosion
protection measures, nominated tree protection measures, etc
as per specifications, for approval. Complete Existing Condition
Dilapidation Inspection reports on all surrounding buildings,
structures, and access driveway. Establish all slope stability
survey monitoring points.

e Initial Site Access and Parking
Construct temporary benching and turn-around areas on site
and establish site office, temporary utilities connections, and
recheck survey monitoring. Build sediment & erosion control
measures, temporary stormwater collection and disposal.

It may be economical to lease additional vacant land in the area
to provide temporary parking of construction vehicles, and
storage of equipment and materials. A vacant lot exists on
McAnally Drive.

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3.5

Parking would be prohibited in the access driveway running
from Seaview Tce to the site, and in the Council Beach Carpark.

e Contiguous Piling

Complete ground injection grouting (to ensure there is
absolutely minimal disturbance to surface sands,) temporary
access tracks and/or platforms, and install reinforced CFA
contiguous pile walls. The grout piling rig can be off-loaded in
Seaview Tce and driven on rubber tracks to the site, as
discussed with a Piling contractor, cement grout and reinforcing
is to be delivered progressively as the piling proceeds.
Temporary parking and materials storage will be at the south
west corner of the site.

e Excavation Works
A small excavator will be sufficient to remove and load sand into
normal-sized tip trucks for removal from site, perhaps with a
small hoist, Conveyor or crane from lower terraced areas.
Stockpiling of material on site will be limited by Geotechnical
approval to avoid localised surface slips. Subject to more
detailed analysis it may be possible to stockpile some materials
in areas where the stiff clays and/or weathered sandstone are
closer to the surface.
Temporary access ramps & terraces can then be constructed
below the contiguous piled walls to create additional temporary
parking and storage areas across the site. Refer to our drawing
14517 - P4.

e Foundations and Screw Piling
Once the main bulk excavation levels have been achieved,
stable terracing can be prepared to expand access, parking and
material storage on-site.

The Screw Piling Rig can be brought in on rubber mats from
Seaview Terrace, and piles delivered in short lengths and
welded together on-site as lengths of pile are installed.

e Structural Works
The foundation beams, pile caps, floor beams, slabs, columns,
and load-bearing walls etc, can be constructed by traditional
methods with materials being delivered readily via the access
driveway as required. The length of construction materials will
be limited by the size of delivery vehicles which can safely
access the bitumen driveway.

Construction of Retaining Walls and Excavations
The majority of the site is sloping at approximately 26° towards the

north-east while the south-east and north-west areas of the block
slope much more steeply at around 32° towards the east.

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Any material above a 27° line projected from the base of the hill of
slope is considered unstable and totally unsuitable for supporting
any permanent foundations or landscape structures.

The area along the western boundary slopes at approximately 26°
and up to 30° at the north-west corner. The area west and uphill of
the site slopes at a more gentle slope, and is occupied by light-
weight timber residential structures, and a reinforced concrete pool
supported on deep piled foundations.

Our design and suggested construction procedure has taken into
account the critical staged nature of the proposed excavations,
close proximity of adjacent properties (especially the piled pool
structure), the additional soil loadings due to the uphill gradient, the
loose and unstable nature of the upper sand layers (particularly
when vegetation is removed or disturbed) and the limitations of
piling machine size which can access the site.

The key features of our design and construction proposed are:-

e Stabilise surface sands to a depth of approximately 3m, along
BOTH western and south-western boundaries using URETEK
(or similar) ground injection

e Establish survey markers across site and on adjacent properties
for continual regular monitoring during construction

e Install extensive “Sediment/Erosion Control” fences

e Install temporary stormwater collection and disposal system;
install permanent spoon drain and gully pits along west
boundary.

e Avoid ground vibrations by avoiding percussion piling and/ or
compaction.

e Prepare engineered truck turn-around area(s) and access
tracks/ramps

e Construct piled temporary access or engineer-designed cut-fill
access for 50T CFA pile rig and complete the western
contiguous piled walls

e Progressively remove sand east of the new western CFA piled
wall, and construct permanent driveway slab in sections
between the western piled wall and the piled wall on the
seaward side of the driveway.

e Extend temporary access/storage/ramp areas towards north
and back to south-east

e Complete the third CFA piled wall which forms the lower level
platform, and gradually remove the sand to form the lower level
bulk excavation platform

e At all times the retaining walls are fully connected back to the
uphill adjacent wall, drainage is in place, and the CFA piling rig
is operating on stable flat platforms without any risk of slip or
toppling

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e Floor slabs laterally restrained by raking piles will provide
additional permanent horizontal strutting to the base of retaining
walls.

e Excavated sand can be removed by small hoist, conveyor belt,
or crane to dump trucks and used as excellent clean fill at
another project

e Piling contractors have advised it is quite feasible to move the
CFA piling machine on rubber matting or use rubber tyres on
the tracks from the Seaview Terrace cul-d-sac to the site

e Once the contiguous piled retaining systems, piling, screw piles
and raking piles are in place (gradually progressing downslope),
the remaining work will be typical load-bearing walls and formed
in-situ reinforced concrete construction

e Sub-floor drainage will be connected through all contiguous
piled walls into vertical “wick” drains at approx. 6m centres

e Separate subfloor drains will be provided to relieve any
localised ground water build-up.

e Grout piled walls will be patched and grouted where necessary

e A “dry” internal masonry wall and drained cavity will be provided
at all contiguous piled retaining walls

e Back-fill over URETEK grouting with topsoil and re-vegetate for
perimeter planting as per Landscape Details

4.0 Design Loading Criteria

4.1

4.2

General

The following outlines the design loading criteria for the project.
Notwithstanding this outline, the structure will allow for all imposed
loads as outlined by the relevant Australian codes, and any loads
imposed from the selected construction methodology for the project
works. The loads during construction of the contiguous piled wall
must be analysed at every incremental stage of excavation and
strutting.

Construction loads, especially loaded trucks and stored materials
will be agreed and confirmed with Contractor prior to
commencement of construction. This is particularly important for
the first stage construction of the driveway slab.

Codes and Specifications

The structural design of the project will be carried out in accordance
with the relevant Australian Standard Codes of Practice including
but not limited to the following:

AS/NZS 1170 Part 1 Loading Code Dead and Live
AS/NZS 1170 Part 2 Loading Code Wind

AS/NZS 1170 Part 4 Loading Code Earthquakes
AS 3600 Concrete Structures

* *& & &

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4.3

* AS 3700 Masonry Code
* AS 4100 Steel Structures
* Building Code of Australia

Loading Criteria
Refer to the architectural documents for the extent of different floor

use areas and hence different live and super-imposed dead
loadings, unless noted otherwise:-

Dead Load

Floor slabs and beams self weight as calculated
Floor finishing — lobby and terraces Internal 2.0 kPa

(tile and bed) External 3.0 kPa

Air con and plumbing services,

and light weight ceiling 0.75 kPa + point loads
Other 0.5 kPa

Masonry partitions (where required) self weight as calculated
Soil, waterproofing, insulation self weight as calculated
Live Load*

Balconies and stairs 4.0kPa

Residential areas 3.0 kPa (Point Load 1.8 kN)
Internal garages 5.0 kPa (Point Load 9 kN)

Driveway, Service Vehicle
Delivery/Loading Area 15.0 kPa (Point Load 31 kN)
(or construction loading)

Mechanical and electrical
plant rooms 8.0 kPa (min) (Point Load 4.5 kN)

External Terrace Areas 5.0 kPa (min)

«x Design Live Load must never be less than construction
loading

Earthquake Load

The building will be designed for seismic load in accordance with
the relevant Australian Standard being AS/NZS 1170.4.
e Importance Level 2
e Soil Factor: Class Ce (most of loose sand layer to be removed
from building platform)
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4.4

e Earthquake Design Category |

Wind Load

The building will be designed for wind loads in accordance with the
relevant Australian Standards (being AS/NZS 1170.2) for the
following parameters:

Basic Wind Velocity VF - 57m/s (Ult Strength Limit State)
Region - B

Terrain Category - 2.0

Multiplier factors Mz, cat = 0.96, Ms = 1.0, Mh = 1.3
Design Wind Speed - 72 m/s Ult limit state

- 60 m/s Permissible Stress Design

Soil Retaining Structures:
Refer also to final Geotechnical Report

Soil Density = 19 kN/m®
Horizontal Pressure - sloping backfill Ko = 0.75;
horizontal backfill Ko = 0.5
Surcharge: adjacent blocks — allow 10 kPa L.L. surcharge.
Provide vertical wick drainage behind all contiguous piled retaining
structures at 6m centres
Provide continuous sub-soil drains behind all conventional retaining
walls
Factor of safety against sliding:- temporary 1.2, permanent 2.0

Deflection Criteria

a) Horizontal (Lateral) movement (wind and seismic)
Total not greater than Height/500 (at permissible stress
loads)
Inter-storey not greater than Floor to Floor Height/500 (at
permissible stress loads)
b) Vertical movement (dead plus live load)
Slabs and beams are to be designed to achieve the following
maximum deflection criteria:

Incremental Deflection
General Span/500 or 15mm (whichever is less)

Long Term Deflection

Slabs Span/500 or 15mm (whichever is less)
Beams Span/500 or 15mm (whichever is less)
Spandrel Beams = Span/500 or 15mm (whichever is less)

Total allowable 20mm to end spans

(Slab + Beam) 20mm to internal spans

Cantilever Span/250 or 10mm (whichever is less)

Pre camber As required

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5.0 Materials Specification

5.1

drawings)

5.2

5.3

5.4

Concrete
Concrete Strengths (generally, unless noted otherwise on
It is envisaged the following concrete strengths will be used for

various elements across the design, taking special care with
respect to the highly corrosive marine environment.

Floor slabs and beams 32 MPa min internal,

40 MPa external
Load bearing walls and columns 32 MPa min internal,
(typical) 40 MPa external
Foundations 25 MPa min/40 MPa max
Pool 40 MPa

External structural concrete elements of the building will have a
design durability classification B2, which complies with Table 4.3
AS 3600. (40 MPa concrete with 50mm external cover).

Reinforcing Steel

High strength Ductile Grade 500 MPa reinforcing steel will be used
in the design.

Formwork

Formwork class is to be in accordance with the architectural
specifications and the relevant Australian Standards. Tolerances
are to be suitable for the purpose to which they are to be used, but
shall not exceed a maximum deviation of 6mm measured over a 3
meter straight edge. Permanent steel formwork (Condek or similar)
may only be used in internal areas to support suspended concrete
slabs, and must be rigidly propped in accordance with the supplier's
written specification.

Structural Steel

Structural steel elements of the building will be designed in
accordance with the relevant codes. These elements will have a
design durability which complies with AS/NZS 4100. All external
steel and exposed internal steel shall be hot dipped galvanised
and painted with coat of an approved high-build zinc-rich epoxy
paint, followed by a top coat of Polysiloxane, or Polyurethane.

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5.5 Screw Piling

All screw piling is to be hot dipped galvanised and epoxy painted
for the upper 2m, as well as filled with concrete grout.

6.0 Structural Framing System

6.1 General Structural System:

The proposed building is a three-storey reinforced concrete
structure with a reinforced concrete contiguous piled retaining wall
system to support excavations of up to about 3.5m. A mixture of
grout replacement piles and concrete-filled galvanised screw piles
are proposed to support vertical loads, and a range of raking
painted and galvanised screw pile are intended to provide
additional horizontal stability to the foundation by acting in either
tension or compression.

Structural System Summary:

e 450mm diameter contiguous CFA piled retaining walls, founded
sufficiently below excavation level to provide vertical capacity
and passive resistance to horizontal soil pressures
Screw piles ranging from 50-80T to support column loads
Raking screw piles to provide additional horizontal resistance to
soil loads, wind and earthquake loads

e Reinforced concrete ground beams and slabs will be used to
provide adequate permanent horizontal “strutting” of retaining
walls and rotational stability to pile/slab/upper column
connections, and to resist bending moments caused by pile
eccentricity

e Sub-floor areas will be drained to relieve any potential build-up
of ground water pressure

e Areas behind contiguous piled walls will be fully drained by
using drilled-in steel “wick” drains, connected through the base
of the wall and discharged appropriately

e Upper structure comprises reinforced concrete columns, walls
and beam/slab system

e Roof slabs will need a high grade trafficable waterproof
membrane or a trafficable slab may be considered over an
insulated waterproofing layer on the structural slabs.

e Garden terrace and mounded soil areas will be generally
constructed on suspended slabs over voids to avoid imposing
additional soil loads to the steep sandy slopes

e The elevated timber walkway running east-west from R.L.34 to
R.L.26.2 will be supported on 7-8m deep piles, designed to
withstand lateral drag of the loose surface sands.

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6.2 Lateral Resistance

The lateral resistance to wind, earthquake and lateral soil forces will
be provided by a combination of reinforced concrete and blockwork
bracing walls, contiguous piled walls, column/beam framing action.
Raking tension and compression piles will be designed and RPEQ
certified by others based on their own design-installation methods
and shall have the capacity to safely resist horizontal loads from
wind, earthquake and lateral soil pressures, with a permanent
factor of safety against sliding exceeding 2.0.

It is clear that the construction of the fully strutted and braced deep
contiguous piled walls will add significantly to the general stability of
the slope and of the areas uphill from all sections of new work,
including the adjacent properties.

6.3 Drainage

The areas behind the contiguous piled retaining walls will be
drained by the use of vertical perforated “wick” drains at
approximately 6m centres, connected through the piled wall just at
the underside of the floor slab level.

The design will include 100mm sleeved agricultural drain lines in
gravel and geotextile at the bottom of all retaining walls and under
all floor slabs in cut areas throughout the building.

Properly designed temporary and permanent drainage and silt

collection must be installed to avoid the risk of surface sands
washing off site, during and after construction of the project.

BARRY GEORGE - MIE(Aust). CPEng. NPER3, RPEQ 1924

TOD CONSULTING ENGINEERS

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