Asia Baru Construction
We are in civil and building construction with particular specialisation in Water Works and Sewerage project ranging from sewerage treatment plant, river intakes, water treatment plants, storage tanks, reservoirs, pipe laying and major diversion...etc
PROJECTS > Construction of Two (2) Anaerobic Digester Tanks

Project Background
The Jelutong Sewerage Treatment Plant was to be constructed on 14.7 hectares of reclaimed land and will treat the entire raw waste from Georgetown, Penang with an ultimate PE of 1.2 million.

The Energy, Water and Communications Ministry had awarded the Contract to WWE Holdings Berhad. Asia Baru Construction was appointed as a civil sub-contractor to construct the two (2) anaerobic digester tanks (20.0m dia. x 16.0m height) by Cipta Wawasan Maju Engineering Sdn. Bhd (CWM), the process turnkey contractor appointed by WWE Holdings Bhd.

The Letter of Acceptance (LoA) was issued to Asia Baru by CWM on 26th October 2006. The possession of site was on 3rd January 2006. Between the receipt of LoA and actual possession at site on 3/1/2006, a lot of preparatory works and planning at head office were carried out. Among them were:
> Proposed location of Contractor's temporary facilities.
> Project Quality Plan (PQP).
> Submission and approval of design mix (G40 concrete) using 50% OPC and 50% GGBS supplied by Buildcon Concrete Sdn. Bhd.
> Method statement for Jumpform metal system and proposed paneling for wall and dome roof of tank.
> Submission and approval of design calculation for Jumpform and shop drawings.
> Design calculation of temporary falseworks and timber truss system to soffit of curved dome roof.
> Method statement to construct the dome roof and soffit formwork retrieval.
> Method statement for watertightness test.

The scope of work for this project comprised of the following major components:
> The Construction and completion of two (2) anaerobic digester tanks.
> Watertightness testing of the two (2) digester tanks and finishes like internal epoxy protective coating, external painting and handrailing along the edge of the tank roof.
Project Information
Client / Owner: Kementerian Tenaga, Air dan Komunikasi, Jabatan Perkhidmatan Pembentungan
Consultant: Sepakat Setia Perunding Sdn. Bhd.
Main Contractor: WWE Holdings Berhad / Cipta Wawasan Maju Engineering Sdn. Bhd.
Sub-Contractor: Asia Baru Construction Sdn. Bhd.
Date of Commencement: 1st January 2006
Date of Completion: 30th August 2007
Project Methodology
Due to the short construction period of 8 months, steel Jumpform system was used for the erection and construction of RC wall instead of the conventional timber formwork system. Figure 1 and Figure 2 respectively shows the sequence of work by using steel Jumpform system for the construction of RC wall and the overall sequence in the construction of digester tank.

The dimension of the tank is 20m in internal diameter x 16m high whereby the thickness of the initial 8m high wall is 800mm thick and the remaining 8m with wall of 500mm thick. Due to this difference in wall thickness and hence the curvature, modification of the Jumpform was required after concreting the 8m height of both tanks.

The tank wall was divided into two (2) panels i.e. semi-circular in plan and with four (4) lifts, each 4m in height. PVC waterstop was incorporated in both vertical and horizontal joint.

Construction of the dome roof proved to quite a challenge because of its 16m height. Owing to the exorbitant costs of using I-beam falsework system, conventional steel scaffolds were finally used but with steel joist system complete with 10mm thick plywood as working platform at the roof ring beam level. From this working platform, 4 identical quadrants of pre-frabricated timber roof truss system of 10m long and height varying from 0.9m to 1.9m of the correct curvature were hoisted up and placed on top of this working platform. 10mm thick plywood was then nailed to the timber truss system to form the soffit formwork to concrete the 250mm thick reinforced concrete dome roof with temporary 2.0m diameter opening for the retrieval of timber truss system and working platform.

For this, a 150mm x 75mm thick rebate was allowed for the 2.0m opening. 150mm thick precast concrete (G40) panel with matching rebate i.e. 2.3m top diameter and 2.0m bottom diameter complete with built-in 800mm diameter gas dome cast at the ground level and hoisted up to seal the opening. 100mm thick 2nd stage in-situ concrete was then placed and compacted on top of the precast unit to provide an effective seal.

Tank No.1 was fully filled to its top water level on 17th July 2006. Leakages to Tank No.1 were repaired using flexible PU grout. Similarly, tank No.2 was put through water tightness test and all leaks were repaired successfully. After passing the water tightness test, the internal walls were brushed down and its surface treated i.e. all pin /bubble holes were filled up with putty and special paint before epoxy protective coat (Fosroc Nitocote EP403) to a total thickness of about 1000 micron was applied.

CPC was issued by CWM after completion of the external painting was in 30th August 2007 and it did not in any way affect the M&E installation works by CWM. The successful completion of this project marked the beginning of Asia Baru foray into seweragee treatment plant construction.