OH&S News

Managing sand supply to Barrow Island

The Gorgon Project is one of the world?s biggest natural gas projects, developing the Greater Gorgon and Jansz gas fields which are located about 130 kilometres off the north west coast of Western Australia. The LNG plant, owned by Chevron Australia, is being constructed on Barrow Island by Kellogg Joint Venture (KJV), 56km from the mainland. When constructed it will include a three-train gas processing and compression facility. Barrow Island is an A-Class Nature Reserve, and is home to many plants and animals that are not present on the Australian mainland. As such, it is a critical asset for the conservation of Western Australia?s remaining biodiversity. The protection and conservation of the island?s biological integrity is a central consideration for the development of the facility on the island. For this reason, the most crucial aspect of project management from an environmental point of view has been to ensure the introduction of non-endemic plant, animal and micro-organisms is prevented. The Gorgon Project has committed to world-class quarantine management practices, striving for new benchmarks in bio-security, and any contractors working in conjunction with them have been required to adopt an associated quarantine regime of sufficient rigour to achieve these commitments; specifically a ?zero tolerance to invasions? policy with regard to all operations carried out on the island and in its surrounding waters, on the Australian mainland or in countries outside Australia.

Chevron identified sand and aggregate supply to the project as one of 13 pathways for non-endemic species to reach the island in relation to quarantine management. Prior to finalising its tender documentation for the supply of concrete (including mainland sand and aggregate) to Chevron, Holcim Australia approached 360 Environmental, a Perth-based environmental consultancy firm, to conduct a review of its systems and procedures. 360 Environmental then prepared a Quarantine Management Plan and a Quarries Quarantine Management Plan to extend and support Holcim?s existing procedures, as the specifications for quarantine management were far in excess of anything in Holcim?s previous experience.

Holcim was awarded the Concrete Supply Contract for Gorgon in September 2009 and continued to work with 360 Environmental to develop and implement the plans, procedures, work method statements, check lists and auditing tools both for Holcim?s suppliers and its own operations to ensure client expectations were met. 360 Environmental personnel continue to conduct training, supervision and mentoring to Holcim staff, subcontractors and suppliers.

Sand and aggregate supply for Barrow Island constitutes a high quarantine risk due to interstitial spaces that can harbour invertebrates and seeds. During the quarry assessment and selection process, overburden was tested for organic content to assess potential risk to underlying sand destined for supply to Barrow Island. Overburden assessment at the potential sand quarry consisted of analysing overburden samples in accordance with AS 1141.34 (note that this test is routinely carried out to monitor sand quality regardless of the Gorgon requirements). After a positive outcome from the quarry risk assessment process, Holcim?s Nickol Bay Quarry and Turner River Sand Quarry were selected, based on a combination of their potential to be controlled in a way that would satisfy Chevron?s quarantine requirements and the logistical advantages that accompany their geographical location.

Holcim?s management approach to ensuring compliance with Chevron?s quarantine requirements is two-fold: first, to ensure as far as possible that the quarry sites and in particular their specially managed Quarantine Controlled Areas (QCAs) are free from potential contaminants, and second, to have adequate systems in place so that the quarried material remains uncontaminated during transportation to Barrow Island. Despite the supply of aggregate and sand having been identified as one of the principal risks to bio-security, the measures undertaken at the Nickol Bay Quarry and Turner River Sand Quarry have so far met the project policy of ?zero tolerance to invasions?. The principal actions taken by Holcim to mitigate the risk of contamination at the Turner River Sand Quarry includes double screening of material, quarantine fencing, weed and pest management and careful hygiene management (processing equipment, vehicles, etc.).

Double screening of the sand at Turner River Sand Quarry is one of the important measures in place to minimise the risk of contamination, both in terms of unwanted vegetation and also any fauna that may have found its way into the sand. The quarry has two project-dedicated screens that it uses for this purpose. Fencing is used as a quarantine barrier at both Turner River and Nickol Bay to ensure that all Quarantine Controlled Areas (QCAs) have closed off access to pests. Operational areas within the Turner River Sand Quarry are delineated by a perimeter fence and gate. The fences are covered with shade cloth to a height of 1.8 metres as a wind break to reduce ground-tumbling, windblown and other material, especially airborne seeds, entering the Quarantine Controlled Area. The fences also have cloth skirting, which minimises the risk of pests burrowing their way into the QCA. Comprehensive weed and pest management on-site is crucial in ensuring that non-indigenous species are discouraged from inhabiting the area. Post-emergent broad-spectrum herbicide was applied initially to all weeds and plants within the perimeter fence. Residual insecticide and pre-emergent herbicide to remove habitat, food sources and shelter for pests are applied at regular intervals to the quarry area inside the perimeter fence; no plants of any form are tolerated within the operating areas of the quarry. Quarry topsoil removal and storage practices at the quarry minimise the risk that the sand mining operations are not contaminated by topsoil or any insect or plant material. Traps and bait can also be used in the quarry area to catch and kill, as well as hold trapped vertebrates and invertebrates for identification and inspection. The main focus is on known vermin and domestic pests such as ants, termites and snails, as well as locally important species such as frogs. Chevron?s requirements for laboratory testing of samples taken from Turner River Sand Quarry are not onerous. Provided that the correct quarantine processes and procedures are in place, assessment is based more on systematic and frequent visual inspections.

At the Nickol Bay Quarry, aggregates are quarried from two broad depth classes, less than three metres below ground surface and greater than (lower) than three metres below ground surface. These to depth classes have different levels of perceived risk for contamination. Aggregates sourced from less than three metres below ground surface are considered to be at higher risk of contamination, so additional quarantine management measures are required for these aggregates. Aggregates extracted from less than three metres below ground surface undergo washing to minimise the risk of contaminants prior to stockpiling or direct loading for transport. Aggregates must be kept in quarantine-compliant containers or stockpiles to prevent contamination post-processing. To minimise the risk of contamination, freshly quarried material can be stockpiled on a hardstand (a prepared, compacted and well-drained surface not capable of sustaining plant, vertebrate and invertebrate activity) and covered with tarpaulins that have been sprayed or impregnated with an insecticide with residual properties. Other measures include regular herbicide and pesticide treatments and thorough quarantine pre-start checks on all project-dedicated machinery and its allocated transport fleet, and systematic tarping, sealing and tagging procedures.

A project-specific quarantine challenge presented itself in March 2011 when Holcim reported an increase in frog activity at Turner River Dune, following a period of heavy rainfall. Holcim initiated a ?stop-work?, causing a pause in sand supply to Barrow Island. Holcim sought advice from Chevron and KJV, and engaged 360 Environmental to undertake a reconnaissance survey to assess the issue.

Four of the frog species identified at the dune presented a real risk of surviving the transport route to Barrow Island. The four species of most concern were burrowing species with the demonstrated ability to withstand extended periods without access to standing water, taking their moisture requirements from damp sand, the same conditions as the damp and sealed contents of the half-height containers used for transportation.

As a result of the assessment conducted by 360 Environmental, several measures were undertaken to reduce the risk of frogs entering the logistics chain. It was recommended that free water should be minimised as far as practical, objects (such as old vehicle tyres) prone to collecting water be removed, and that additional herbicides and pesticides should be applied around the extraction area to remove potential habitat, food sources and shelter. It was also suggested that a ?survey pad? near the screening plant be smoothed at the end of every day and inspected for tracks in the morning to monitor frog activity. During high risk periods for frog activity it was decided that sand destined for Barrow Island should be loaded immediately after screening rather than stockpiled for any length of time.

Monitoring for frogs at Holcim?s batch plants on Barrow Island has also been undertaken. Holcim was awarded a Quarantine Operational Response Award by Chevron Australia in recognition of its response to the frog outbreak at Turner River Dune and its subsequent management of the risk. There have been no quarantine breaches involving Holcim on this project to date.

In summary, Holcim?s approach to the Gorgon Project is based around practical, preventative environmental and quarantine management rather than resorting to highly analytical or technical measures. It is a case in point of how effective a comprehensive but low-tech management system can successfully achieve compliance with highly stringent quarantine requirements.?

Mary Rose Sidgwick is a technical writer at Perth-based environmental consultancy firm 360 Environmental.

Leave a Reply

Send this to a friend