MEIC Ltd completed the role of Civil Contractor for sister company, Glan Agua Ltd on the Design Build Contract for the Merck Millipore WWTP Compliance and Capacity Upgrade. Civil Works included:
Earthworks and Excavations
Bulk earthworks was required to reduce the levels (particularly the Eastern and Northern areas) of the existing WWTP. A geosynthetic clay (or similar approved) lined swale and catchment pond was constructed to the Eastern and North-Eastern boundaries of the site to serve as environmental protection to the adjacent lands during the construction works. The type of liner used is a Bentomat AS50 geosynthetic clay liner (GCL) (or similar approved). Bentomat AS50 consists of a layer of natural sodium bentonite encapsulated between woven and non-woven geotextiles, which are needle-punched together to provide internal reinforcement. The internal reinforcement minimizes clay shifting, thus allowing the GCL to maintain consistent low permeability and maximum performance under a wide variety of field conditions.
The bulk excavations generally lowered the level of the areas where works were to be constructed. Any sides to the bulk excavations were battered back at a safe angle to ensure slope stability.
Modifications to the existing fence line included provision of three new sets of access gates at the Western boundary of the WWTP site. New galvanised palisade fencing (to match existing) was placed along the revised site boundary to the North, East and South of the site.
Construction of concrete hardstandings and concrete roadways within the entire footprint of the site, such that all areas of the site will be sealed to prevent runoff from potentially contaminating the underlying ground in the event of a spillage.
The entire surface area of the site including rooftops are drained into a stormwater collection network. The stormwater network shall discharge into the existing pumping station, where it shall then be pumped to the existing stormwater manhole outside the South Western end of the WWTP site.
The stormwater collection network was designed and constructed in accordance with <Clause 2.4> and its sub-clauses of Section 6: Civil, Structural and Architectural Specifications of the Contract Documents.
Aeration Tank No. 2 / Catch and Release Tanks Piled Foundations:
This is involved the construction of 40 no. Ø450 mm CFA end bearing piles, each capable of transmitting vertical loads of up to 650 kN and horizontal loads of up to 50 kN. A piling platform was constructed to accommodate the piling rig. The excess pile lengths were cut and trimmed to cut-off level. The piled foundations were designed, constructed and tested in accordance with the provisions of the Institution of Civil Engineers (ICE) Specification for Piling and Embedded Retaining Walls (SPERW).
Reinforced Concrete Base Slab:
A reinforced concrete base slab was designed and constructed in accordance with the CSA Specification. The multi-purpose slab shall be designed to incorporate the pile caps and ground beams and to transfer the design loads from the Aeration Tank to the piled foundations.
Glass-Lined Steel Tank:
Aeration Tank No. 2 was constructed using a glass-lined steel tank and a glass-reinforced plastic (GRP) roof. The tank was constructed on top of the reinforced concrete base slab, with a 150 mm thick “seal pour” concrete base. The tank was provided with a low level access manway and an access ladder with a viewing platform at eaves level. The roof was constructed of ‘beam and infill’ GRP to allow the removable diffusers to be lifted out of the tank.
MCC and Laboratory Building
The MCC and Laboratory (MCCL) Building shall be constructed in accordance with the building regs and the roof shall be designed for Factory Mutual (FM) approval.
Dewatering Building Extension
Extension of the existing sludge dewatering building.
The site roadways were constructed of 175 mm thick reinforced concrete. High yield steel mesh reinforcement provided throughout. The roads was designed and constructed in a manner such that optimum stormwater drainage conditions can be provided. Expansion joints were provided for. Precast concrete kerbing were constructed along the perimeter of the site to provide a liquid retaining seal and thus ensure that no leakage to ground can occur.
The roadways will be delineated from the hardstandings by permanent linemarking.
Various plinths shall be provided to the following structures:
Generator and Fuel Tank
These plinths will be reinforced concrete and shall be individually designed and constructed to transfer the loadings from the various structures to the supporting ground beneath.