Method Statement detailing the Protective Measures on ... · Method Statement detailing the ... of...

Method Statement

detailing the

Protective Measures on Declared Monument

Buildings

at

Former Marine Police Headquarters, KIL 11161

Conditions Imposed under Section 5(12) of Environmental Impact Assessment (EIA) Ordinance, Cap.499

Application for Permission to Apply Directly for Environmental Permit Application No.: DIR-094/2003

Project Proponent: Flying Snow Limited

Prepared By: All Arts Architectural Design and Research Limited

March 2004

Method Statement detailing the Protective Measures on Declared Monument Buildings

1. Background Information

1.1 The Submission

1.1.1 This Method Statement (MS) detailing the protective measures on the Declared Monument Buildings at Former Marine Police Headquarter (FMPHQ), KIL 11161(the Subject Site) is prepared and submitted under the condition imposed under the Environmental Impact Assessment (EIA) Ordinance, Cap. 499, regarding application for permission to apply directly for Environmental Permit [Application No.: DIR-094/2003] and the Permit Condition 2.4 of Environmental Permit No. EP-184/2004 (the Permit).

1.1.2 This MS outlines the objectives, standards, scope and implementation schedule of the protection measures for:

the Main Building of Former Marine Police Headquarters, the Stable Block, the Signal Tower and the Accommodation Block of the Former Fire Station

during the earthworks and building works stage within this site of cultural heritage.

Main Building of FMPHQ Stable Block Accommodation Block of Former

Fire Station Signal Tower

All Arts Architectural Design and Research Limited

1



2

1.2 The Declared Monument Buildings

1.2.1 The buildings of historic significance highlighted in Item 1.1.2 of this section are regarded as the “Declared Monument Buildings”(DMB) referred in the Permit Conditions. The location plan of the DMB is shown in Appendix I-1. The FMPHQ and its compound, including the DMB have been declared as monuments under the Antiquities and Monuments Ordinance (Cap. 53) on 23 December 1994.

1.2.2 The Main Building of FMPHQ, Stable Block and Signal Tower are located at the central and northern portion of the Subject Site at an elevation of about 14.5 mPD whereas the Accommodation Block of Former Fire Station is located at about 4 mPD at the same level of Salisbury Road.

1.3 Other Applicable Ordinances

1.3.1 The MS involves protective measures that are in themselves defined as “building works” under the Buildings Ordinance. The Buildings Ordinance is considered the applicable ordinance in this regard. Before commencement of these works, approval and consent have to be issued by the Buildings Authority.

1.3.2 Under Section-6 of Antiquities and Monuments Ordinance (Cap.53), no person shall- excavate, carry on building or other works, plant or fell trees or deposits earth or

refuse on or in a proposed monument or monument; or demolish, remove, obstruct, deface or interfere with a proposed monument or

monument, except in accordance with a permit granted by the Authority (the Antiquities Authority). This permit is referred as “Section-6 Permit” in this MS.



3

their exother p

2. Objectives and Standards

2.1 Objectives

2.1.1 This MS of protective measures forms part of the overall conservation scheme of the project.

2.1.2 The objectives of the MS shall follow that of the overall conservation scheme, which are:

to produce a restoration of a complete Victorian-Colonial complex to an international standard that will be acknowledged as one of the best of its kind in the Asia-Pacific region;

to produce an economically viable reuse of the Lot, while preserving the setting and the fabric of the Historic Buildings;

to make limited and controlled intervention to the Lot and the Historic Buildings in order that their future heritage value are not diminished by inappropriate and non-Reversible alterations or additions.

2.1.3 Down to the construction level, the protection measures aim to preserve the DMB at isting locations and elevations and protect them from adverse ground movement and

otential impacts by physical and management measures.

2.2 Standards

2.2.1 The conservation aspects of the project would be carried out to an international standard, reference should be made to established international principles; Charters to be respected, in particular:

1964 – Venice Charter (ICOMOS)

1978 – Burra Charter (Australia ICOMOS)

2.2.2 Involvement of conservation experts in preparation of conservation schemes, method statement for protection and project supervision through out the project. The Technical Schedule and Conservation Guidelines established by the relevant Authority are followed.

2.2.3 The standard of works mentioned in the MS will follow that of Permit Condition issued under the Antiquities and Monuments Ordinance, Approval and Consent Conditions under the Buildings Ordinance as well as the TM–EIAO.



4

3. Descriptions of Earthworks and Building Works

3.1 General

3.1.1 The MS of protective measures for the DMB are prepared in relation to the protection of the site of cultural heritage during the earthworks and building works stages.

3.1.2 The earthworks and building works are elaborated according to the stages of construction in Item 3.2 of this Section while their potential impacts and proposed protective measures are described in Section 4.

3.2 Stages of Construction

Site Formation [Involving earthworks] 3.2.1 Site formation includes bulk excavation, demolition of existing temporary structure

and construction of retaining walls. The Main Building of FMPHQ, Stable Block and Signal Tower will be protected and preserved in-situ by means of construction of retaining walls.

3.2.2 Subject to the result of the site investigation and detail design, a preliminary proposal of using pile wall /concrete ring /steel ring as the retaining wall to retain the DMB is considered feasible.

3.2.3 After the construction of the retaining walls for DMB, the earth will be removed in phases by open cut excavation until the level of the hill was brought down to the existing pedestrian level.

Building Foundation [Involving earthworks and building works] 3.2.4 The construction of building foundation involves shallow foundation work and

installation of piles to support the future new buildings. Replacement pile or / and shallow foundation on reliable stratum appears to be suitable to support the future buildings composed of retail facilities.

3.2.5 The earthwork involves localized excavation and piling work. To facilitate the excavation process, backhoe with breakers shall be employed to excavate the ground to the founding levels.

3.2.6 A system of shallow foundation and some piles is proposed for the new building subject to current available information. No new foundation would be employed for the monument buildings for the aim of minimum intervention according to current information. The proposal shall be reviewed from time to time.

Superstructure Works [Involving building works] 3.2.7 Conventional reinforced concrete structure will be adopted for the new building.

Structural system adopting a beam/slab or flat slab arrangement with column frames and shear walls appears to be feasible. The works will involve erection of formwork and falsework, fixing of reinforcement and concreting.


4. Potential Impacts and Proposed Protective Measures

4.1 Pre-Construction Phase

Impacts

4.1.1 There are protective measures at the pre-construction phase that will be carried through stages of work for the purpose of protection of the DMB.

4.1.2 During this phase, there are site mobilization, the preparation of site equipment, delivery of construction materials and construction of site hoarding. There will be site vehicles and construction plants in the site.

4.1.3 The potential impact will be the accidental damage of the DMB during the mobilization, the transportation of the construction plants, demolition of temporary structures and during the subsequent foreseeable work stages.

Proposed Protective Measures Chain Link Fence

4.1.4 In order to keep an effective distance between the construction vehicles and heavy machinery from the Main Building of FMPHQ and Stable Block, a chain link fence was constructed along the periphery of the two monument buildings and the vehicular access road.

Chain Link Fence at around Main Building (View 1)

4.1.5 The chain link fence is of 3000mm in height and at a minimum distance of 2000mm from the Main Building and Stable Block. It is constructed of steel and has three access doors. It is connected to the existing chain link fence at both ends in order to provide a complete separation.

4.1.6 The construction material, details, alignment, location of access doors of the chain link fence were approved by the issuance of Section-6 Permit under Antiquities and Monument Ordinance (Cap. 53) on 26 September, 2003. The approval letter and the layout plan of the chain link fence are shown in Appendix II-1 and Appendix II-2 respectively.

4.1.7 The chain link fence will be removed to give way for piling works associated with the retaining wall around Main Building of FMPHQ and Stable House. The protection measures will be replaced by other temporary fence-off structures to be described in the earthwork section.

Chain Link Fence at around Main Building (View 2)


5


Proposed Protective Measures (cont.)

Steel Hoardings 4.1.8 A steel hoarding and covered walkway is

constructed around the project site. There are two portions of the steel hoarding that locate within the Declared Monument Boundary which are: (A) constructed at the space between the

Accommodation Block of Former Fire Station and the existing slope.

(B) Constructed at the space between the Main Building of FMPHQ and the northern site boundary.

Steel Hoardings (A) constructed next to the Accommodation Block of the Former Fire Station

4.1.9 There will be machinery for bulk excavation and transportation of the excavated materials in the site formation or earthwork phase. The proposed gantry of the site will be located next to the Accommodation block of Former Fire Station. In this connection, a steel hoarding is proposed to screen off the site of earthwork and the Accommodation Block of Former Fire Station and to keep a physical separation.

4.1.10 The hoarding between Main Building and northern site boundary is to maintain a clear physical separation and to outline a definitive heritage protective zone for the subsequent construction stages.

Steel Hoardings (B) constructed between the Main Building of FMPHQ and the northern site boundary

4.1.11 The steel hoarding for Item 4.1.8 (A) is of 4500mm in height and constructed of steel beams on concrete base. The steel hoarding for Item 4.1.8 (B) is of 2400mm in height and constructed of steel channels with corrugated sheets on concrete base. The layout, construction details and materials of these portions of steel hoarding were approved by Buildings Department on 13 November 2003 and by the issuance of Section-6 Permit under Antiquities and Monument Ordinance (Cap. 53) on 17 January 2004. The Section-6 Permit approval letter and the location plan of the portion of steel hoarding are shown in Appendix III-1 and Appendix III-2 respectively.


6



7

Scaffolding and tarpaulins around existing barracks during demolition

4.1.12 The existing barracks at the foreground of FMPHQ Main Building have to be demolished under Lease Conditions. In order to screen off the demolition site from the DMB, scaffolding and tarpaulins are employed around each of the barracks.

4.1.13 The scaffolding should be at least 3500mm high and firmly related to each other and the ground. The scaffolding also includes the protection for the demolition of an existing water tank and pylon. The layout plan of the scaffolding is shown in Appendix IV-2.

4.1.14 The layout, construction details, materials and other technical requirement of the scaffolding were approved by Buildings Department on 10 October 2003 under the demolition plan submission and by the issuance of Section-6 Permit under Antiquities and Monuments Ordinance (Cap.53) on 8 December 2003. This letter of approval for Section-6 Permit is shown in Appendix IV-1.

4.1.15 The scaffolding and tarpaulins will be removed upon completion of the demolition work for the barracks.

Establishment of a Control Zone for the construction crane

4.1.16 During the Building Construction stage, there will be tower crane for mobilization and delivery of materials around site. The exact height of tower crane will be designed by the building contractor.

4.1.17 During the delivery process, there may be risk of accidental damage of DMB due to fall of materials when such materials are carried across the buildings by the tower cranes.

4.1.18 A Control Zone demarcating the overhead space of DMB to be restricted from the entry of the tower cranes will be established during the subsequent building stages. Appendix V-1 shows the layout and alignment of such Control Zone.

4.1.19 No overhead entry of the tower crane into the Control Zone will be allowed except by written request by the building contractor. In such circumstances, the duration, reasons and enhanced protective measures during such process of the entry will be assessed by the project team including project architect, engineer and conservation consultant. Technical Competent Person from the contractor should be present monitoring the whole process of entry of the tower cranes.



8

4.2 During Earthworks and Building Works

Impacts

4.2.1 The ground condition of the site of cultural heritage is prone to certain degree of effect due to the substantial earthworks to be carried out in the site. The monument buildings within the site will be subject to geotechnical and structural effect such as:

Ground Settlement Building Settlement Tilting Deformation

4.2.2 The above geotechnical impacts and consequences will also be causative of the piling, installation of soil nails and construction of the retaining pipe-pile wall. The work procedures and methodology employed are critical to the mitigation for such adverse effects.

4.2.3 As the stability of the DMB relies heavily on the soil capacity of the site, it would be potent to ensure the integrity of such existing soil mass during the process of its eventual removal in the stage of bulk excavation. The protection of the soil mass is the protection for the DMB.

4.2.4 The impact to DMB during the building work stage is expected to be of similar nature to that of the earthworks stage, that is the vibration effect and ground movement.

Proposed Protective Measures

Prohibition of Percussive Piling 4.2.5 For the protection works to the DMB, replacement piling method is considered more

suitable than the displacement piling or percussive piling for it would induce less vibration due to driving force and in turn generates less adverse impact on the monuments as well as the surroundings. Based on the available ground investigation information, the proposal of the protection works are shown in Appendix VI-1.

4.2.6 This proposal of piling work has been vetted by Buildings Department and Civil Engineering Department and has been approved on 13 February 2004. The proposal is also under Section-6 Permit approval.

Prohibition of Blasting 4.2.7 Local open cut excavation with a safe slope angle in front of the Main Buildings of

FMPHQ, Stable Block and Signal Tower will be carried out during the bulk excavation period. According to the geotechnical assessment result, the site is mainly composed of fill and in-situ materials with small percentage of rock at lower level near to the junction of Canton road with Salisbury Road. In this connection, no blasting is anticipated.


Avoidance of concurrent pipe pile driving 4.2.8 In order to avoid the generation of cumulative ground vibration impact on the DMB,

the concurrent pipe pile driving for tree ring retaining structure and retaining walls for Main Building of FMPHQ, Stable Block and Signal Tower less than specified distance when the pipes are about to penetrate the bedrock will be prohibited.

4.2.9 The prohibition of concurrent pipe pile driving less than specified distance is also subject to the control under the relevant subsidiary regulations under the Buildings Ordinance.

Sufficient temporary support for the Monument Buildings 4.2.10 There will be no additional foundation system for the monument buildings. In this

connection, their stability relies on the integrity and capacity of the originally existing ground soil mass. During the bulk excavation period when the existing soil is removed in stages, temporary structures have to be installed following the stages of work. They included:

Shoring System Temporary Soil Nails Ground Anchors

4.2.11 These protective measures are geotechnical works. They have been vetted by Buildings Department and Civil Engineering Department and has been approved on 13 February 2004 under the site formation plan submission. The site formation plan submission is also under Section-6 Permit application process.

4.2.12 These temporary supporting structures are installed to achieve a conjunctive effect for the overall lateral support. As there may be unforeseen ground condition during the course of excavation. The layout will be subject to amendment when such problem occurs. The layout plan of these supporting structures is shown in Appendix VII-1.

Installation of monitoring system and checkpoints 4.2.13 The performance of the protective measures have

to be checked by a monitoring system in which checkpoints on settlement and ground movement will be assigned.

4.2.14 The installation for the checkpoints such as ground settlement markers, building settlement markers, tilting markers, piezometers, inclinometers, load cells, crack tell-tales, strain gauges, etc. All monitoring records include graphical plots and tables should be kept on site for inspection during Qualified Site Supervision as if required under the Buildings Ordinance.

An installed telltale for an existing crack at FMPHQ

4.2.15 In case of contingent geotechnical situations, actions should follow that advised and designed by qualified site supervisor or other professional


9



10

consultants responsible for the works.

Enhanced protection during heavy rainfall 4.2.16 There should be enhanced protective measures of earthwork during heavy rainfall.

All earth works for the Declared Monument Buildings shall be graded and sealed to

Ensure run-off and to avoid ponding Prevention of collection of rainwater at around Declared Monument Buildings

by devising proper temporary surface channel and discharge points during the construction period.

4.2.17 These associated protective works are included in the site formation plan submission and has been approved by Buildings Department on 13 February 2004. The submission is also under approval process of Section-6 Permit application.

4.2.18 In any case of occurrence of adverse effects due to heavy rainfall on the Declared Monument Buildings, immediate reporting to Architect and Engineer should be taken by the contractor.

Good Site Practice and Management 4.2.19 To submit to Architect, Engineer and Conservation Consultant for approval on use

of heavy machinery, method statement and programme intended to be carried out on site during the earth work and building work stages.

4.2.20 To provide the appropriate frequency of supervision by technically competent persons (TCPs) during the whole process of earth work and building works within the declared monument boundary as if required under the Buildings Ordinance.

4.2.21 To site cranes, mobile plants and heavy machinery as far away from the Declared Monument Buildings as possible. In all cases of transportation of heavy machinery and materials to and away from the DMB, the operation should be over-looked by the resident competent person provided by the building contractor. The construction site setting has to be monitored by the professional personnel from the contractor, architect and engineer streams.



11

5. Implementation Schedule of the Proposed Protective Measures

Ref: Proposed Protective

Measures Location of the

Measure Who

implement When to

implement *Applicable Ordinances

or Regulations

Objectives of the recommended measures

& main concern to be addressed

4.1.5 To construct chain link fence of 3000mm high and at a minimum distance of 2000mm from the Main Building & stable Block

Around the Declared

Monument Building of

FMPHQ

Contractor Before construction

was commenced

A&MO

To keep away the construction vehicle and heavy machinery from the Monument Buildings

4.1.8(A) To erect steel hoardings of 4500mm high

Besides Accommodation Block of Former Fire Station and


was commenced

A&MO &

BO

To protect the DMB from the proposed earth work and excavation work by clear physical separation

4.1.8(B) To erect steel hoardings of 2400mm high

Along northern

boundary of FMPHQ site


was commenced

A&MO &

BO

To maintain a clear separation and outline a definitive heritage protection zone

4.1.13 Scaffolding and tarpaulins around existing barracks during demolition

Surrounding existing barracks,

water tank and pylon to be demolished

Contractor Before Demolition

A&MO &

BO

To enclose the barracks during demolition to prevent any adverse impact and damage to the adjoining Monument Buildings

4.1.18 Establishment of a Control Zone to limit the entry of overhanging tower cranes

Site Contractor During Building

Work Stage

A&MO

To prevent the accidental falling of materials during delivery by the tower cranes

4.2.5 Prohibition of percussive piling

Site Contractor All Phases A&MO &

BO

To eliminate possibility of generating any significant ground vibration impact on the DMB

4.2.7 Prohibition of blasting

Site Contractor All Phases A&MO &

BO

To eliminate possibility of generating any significant ground vibration impact on the DMB



12

Ref: Proposed Protective Measures

Location of the Measure

Who implement

When to implement

*Applicable Ordinances

or Regulations

Objectives of the recommended measures

& main concern to be addressed

4.2.8 Avoidance of concurrent pipe pile driving near the tree ring and the Main Building of FMPHQ when the piles to about to penetrate the bedrock.

Site Contractor During earthwork

stage

A&MO &

BO

To minimize the generation of cumulative ground vibration impact on the DMB

4.2.10 Installation of temporary supporting structures

Site Contractor During Earthwork

and building work stage

A&MO &

BO

To provide lateral support to the DMB during process of bulk excavation and building work stage and to ensure the stability of the excavated soil mass

4.2.14 Installation of checkpoints including ground and building settlement markers, tilting markers, piezometers, inclinometers, load cells, crack tell-tales and strain gauges



A&MO &

BO

To provide a continuous monitoring system on the DMB during the earthwork and building work stage.

4.2.16 Construction of enhanced measures to protect the open earthwork during heavy rainfall


stage

A&MO &

BO

To mitigate any adverse impacts due to heavy rainfall during the earthwork and building work period on the stability of DMB

4.2.21 To ensure site cranes, mobile plants and heavy machinery to be placed far from the DMB and site work to be supervised by competent personnel



A&MO &

BO

To minimize the possibility of any adverse effect or damage to the DMB in the process of site mobilization or due to poor construction site management

Abbreviation A&MO – Antiquities and Monuments Ordinance BO – Buildings Ordinance Notes * Reference should be made to Section. 1.3.3



13

Appendices

Method Statement detailing the Protective Measures on ... · Method Statement detailing the ... of...

Documents

Transcript of Method Statement detailing the Protective Measures on ... · Method Statement detailing the ... of...