PROJECT DESCRIPTION
Existing and aged timber wharf structures at PrimePort were unable to provide safe and reliable mooring for increasingly large vessels. In conjunction with the wharf upgrades carried out to extend the structures useful lines, new shore bollards were designed and constructed to provide reliable high load capacity bollards for three wharves at PrimePort.
The upgrade programme was carried out in a live port environment, requiring careful planning and minimal effects on operators. The new bollards now provide assurances for safe and effective mooring for increasing vessel requirements and meet current design standards.
CLIENT BRIEF/PROJECT CHALLENGES
The existing timber wharf structures at PrimePort have limited capacity for large bollard loads. With larger vessels mooring at PrimePort additional large bollard capacity was required for the No.1 & No.1X wharves and the North Mole container terminal.
THE SOLUTION
The shore bollard solution for each wharf was bespoke due to the differences in original construction of the backland.
The No.1 wharf seawall was constructed from friction bearing mass concrete blocks. The shore bollard solution included drilling oversized holes in the existing concrete seawall and installing concrete filled steel piles which were grouted into the concrete seawall and extended into the bollard beam. Additional steel piles were drilled into tight fitting holes along the front of the bollards to interlock the concrete block seawall.
The No.1X wharf breakwater was constructed using similar mass concrete blocks as was used in No.1 wharf seawall. However, as it is a breakwater this extends out into the harbour with both sides exposed to the sea. Over time the concrete blocks have deteriorated and there are gaps between the concrete blocks allowing water to flow through the breakwater. An alternative solution was required that consisted of a larger number of smaller diameter concrete filled steel piles installed on raked angles. A cutting blade was used to ensure the piles were drilled tight to the concrete blocks. The piles were partnered with a series of dowel bars drilled and grouted into the top of the seawall and embedded into the new concrete bollard beam. This solution utilised the limited space available from existing pipe line constraints.
The North Mole was originally formed from random rubble around 1940. The North Mole was extended with the addition of an adjacent random rubble mole and the construction of a new timber wharf in the late 1960s. The zone between the two random rubble moles was filled with loose beach shingle. The optimum location for the new shore bollards was located between the random rubble moles. The shore bollard solution used large diameter concrete filled piles to provide the uplift capacity whilst the majority of the lateral load is resisted by passive pressure on the large concrete bollard beams into which the shore bollard units are fixed.
OUTCOME/CLIENT BENEFITS
Large vessels apply significant forces to mooring infrastructure and failure of mooring systems can result in sizable cost to the client.
The No.1 and North Mole shore bollards have provided PrimePort with reliable 100T bollards for mooring large vessels.
Due to the original construction and deterioration of the No.1X breakwater, the new shore bollards were limited. However, through innovative design we were able to achieve 50T capacity for each of the No.1X shore bollards.
All shore bollard solutions replaced bollards previously connected to the existing timber wharves resulting in higher bollard capacities and a robust load path for the bollard forces.
