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Bankside Update Page
Background
History
Remediation Objectives
Health and Safety Plan
Contamination Risks
Human Health Risks
Environmental Risks
Air Monitoring
Materials Handling
Stormwater Management
Air Quality
Spill Contingency Measures
Background
The biggest remediation project in Canterbury will start in April 2009 when the investigation and clean up of the World War II fuel depot at Bankside commences.
Originally built in 1942 as the main fuel store base for the ‘secret’ Te Pirita airfield, the site has been used as a dumping ground since the 1980s, despite it being situated on private land owned by SPBL.
The 1991 Resource Management Act made landowners responsible for clean up costs and SPBL anticipates the clean up will cost several million dollars. The Ministry for the Environment has allocated $100,000 towards the investigation from its Contaminated Sites Remediation Fund. Environment Canterbury is contributing towards the investigation costs and working in partnership with SBPL as project advisor.
The remediation is challenging - largely because it is not known what has been dumped in the pit.
The pit is located within a rural area on Breadings Road, Bankside in the Selwyn District. The site lies 320 m northwest of State Highway 1. The site comprises a brick lined pit of approximately 24 m in diameter and 10 m deep. It was built to hold 750,000 gallons (or 2.8 million litres) of fuel.
History
By early 1942 the lightening speed at which the Japanese army was moving down through the South Pacific after its attack on the American forces at Pearl Harbour raised security concerns in New Zealand. The looming possibility of a Japanese invasion demanded an increased effort to defend New Zealand’s shores. The United States was also looking for additional airfields in the region that would be safe bases and refuelling stations for its aircraft.
Te Pirita, near Horarata on the Canterbury Plains was identified as an ideal site for a secret airfield and associated aviation fuel depot. Work began on building air-strips and at nearby Bankside, a massive below-ground, brick-lined tank. The site would be the base for a squadron of American B-17 Flying Fortresses. The depot was still under construction when the Japanese advance was halted and the threat of invasion evaporated. The Te Pirita airfield was no longer needed, work ceased and the site slowly reverted to farmland.
Today, the Bankside fuel depot site is the largest and most intact example of all the blast walls built during the 1940s war effort in New Zealand. It is also one of only five remaining tanks out of the 15 originally built. Its historical significance saw it listed as a Heritage Site in the Selwyn District Plan and recently received a Category II registration from the Historic Places Trust.
The newspaper clipping below was one of the first public announcements about the Te Pirita airfield appearing in November 1945.
 Remediation Objectives
The overall remediation objective of the project is to safely remove the waste materials in the pit. Contamination of natural soils beneath the pit floor may remain, requiring further investigations and potentially remediation works.
There has been no detailed assessment of the waste materials contained in the pit. However, it is understood that the pit is likely to contain a variety of potentially toxic, flammable and potentially explosive materials including pesticides and herbicides (empty unwashed drums and partially full or full drums), miscellaneous chemicals, tyres, batteries, metals wastes, asbestos containing materials, general domestic wastes, and contaminated soils. In addition there is an unsubstantiated suggestion that some ordnance materials may also have been disposed at the site beneath the general waste.
Health and Safety Plan
Prior to any work commencing on site a comprehensive Health, Safety and Environment Plan (HSEP) will be prepared and implemented.
The HSEP will include (but not be limited to the following):
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Roles and Responsibilities, and the Line of Authority (eg. Site Safety Officer)
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Emergency Response and First Aid
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Fire Prevention and Control
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Worker and Visitor Induction requirements
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Visitor Management
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Detailed Assessment of Hazards and Mitigation/Management Measures required
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Health and Safety Management Zones
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Personal Protective Equipment (PPE) requirements and PPE Upgrade (trigger) Levels
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Personal Hygiene and Decontamination Procedures
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Confined Space Entry/Exit Procedures
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Air Monitoring requirements (dust and vapour)
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Worker Health Monitoring
The HSEP shall be prepared and site works carried out in accordance with relevant regulations, codes of practice and guidelines including but not limited to:
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Health and Safety in Employment Act 1992/2000
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AS/NZ 2865-2001 Safe Working in Confined Spaces
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Health and Safety in Employment Asbestos Regulations (1998)
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Health and Safety Guidelines on the Cleanup of Contaminated Sites (OSH, 1994)
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Approved Code of Practice for Safety in Excavation and Shafts for Foundations (OSH, 1995)
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Resource Management Act (1991)
Following is some specific detail on how mitigation will be carried out on site.
Contamination Risks
Of the potential contaminants identified the pesticides and herbicides, dinitrophenol, and ACM, are considered to be of the most significance with respect to potential risk to human health. Mitigation measures put in place for these potential contaminants will be sufficient for protection against other contaminants that may be encountered during the remedial works program (eg. petroleum hydrocarbons, heavy metals). Due to the health and safety risk of personnel working in a confined space with hazardous chemicals, “end dumped waste” will be removed without placing personnel in the pit.
Human Health Risks
A number of the pesticides and herbicides potentially present are known or suspected carcinogens (eg. 2,4-D, DDT, chlordane, lindane) and/or mutagens (DDT) and teratogens (Aldrin). Potential human health exposure routes comprise inhalation (dust and vapours), ingestion, skin absorption, and skin and/or eye contact. Exposure to chemical hazards will be controlled by a combination of monitoring, good hygiene practices, decontamination procedures, site set up and wearing appropriate personal protective equipment. These control measures will be set out in a site specific safety plan (HSEP) to be prepared for the works.
Environmental Risks
Potential risks to the environment primarily comprise potential product releases (eg. burst drum), the generation of potentially contaminated dust, and potential discharge to the environment of contaminated stormwater.
Transport of waste materials will be carried out in accordance with the relevant provisions of the Transit New Zealand Act 1989, the Dangerous Goods Land Transport Rule 1999, NZS 5433: 1999 - The Transport of Dangerous Goods on Land, and with any other relevant legislation. Waste removed offsite will be traced to approve waste disposal sites using the WasteTRACK system authorised by the Ministry for the Environment.
Air Monitoring
Potential adverse effects on air quality are primarily expected to be from odour and dust related to the remediation. All possible steps will be taken to mitigate any potential effects and an extensive air monitoring program will be used to actively manage the remediation process and ensure that mitigation measures are appropriated.
An air discharge consent will be obtained from Environment Canterbury to cover the project. Air Quality monitoring equipment shall be installed and operational at least one week prior to the commencement of the waste extraction programme, and shall not be terminated before the site has been declared fully remediated.
The air quality programme shall be implemented to identify:
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Total suspended particulate levels (TSP), volatile organic compounds (VOC) and agrichemical contaminants at the site boundary.
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Visible dust emissions within the site or beyond the boundary.
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Odour within the site or beyond the boundary.
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When use of water suppression or other mitigation measures have been required.
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Weather conditions including wind direction, strength, direction and rainfall.
Continuous monitoring equipment will have trigger levels set for total suspended particulate and volatile organic compounds based upon the health effects of the contaminant. If the trigger level is reached an audible warning alarm will activate and work on site shall stop until the reason for the alarm is identified and measures are taken to reduce or eliminate the risk, if required. Work shall not commence again until the continuous monitoring data indicates it is safe to do so or if the source of the exceedence can be proven to be from other than contaminated areas.
In order to prevent and to provide for abatement and control of any environmental pollution arising from the proposed remediation works, the following procedures are to be implemented at the site.
Materials Handling
All waste materials will be transferred to sealed skips placed on the bottom of the pit prior to being removed from the pit. The containment provided by the sealed skip will reduce the potential for spillage of contaminants to ground during removal from the pit.
The sweep zone for the crane and/or digger will be lined with plastic draining back towards the pit or the processing area to further limit the potential for any discharge of contaminants to ground.
All material segregation and steam cleaning will be undertaken on the concrete processing pad with all spillage and water drainage retained for offsite disposal.
Stormwater Management
Waste Processing will only occur within the concrete processing area. The concrete processing area has a nib wall around it and is designed to hold flow from rainfall events. The processing slab drains to a silt trap and then to a pump chamber. Pumped wastewater is piped to a 20 m3 holding tank.
Drainage from areas where contaminants are being handled (eg. crane sweep zone) will be discharged to the water storage system associated with the processing area. Any discharge to the pit will be limited to accidental spill or emergency conditions.
Waste water from the site (processing area and toilets and ablutions) will be regularly pumped from the holding tank using a vacuum truck and disposed of at an approved facility.
In addition to the above, a silt fence will be erected along the south-eastern boundary of the site to prevent any eroded soil from leaving the site.
Air Quality
Dust
The principal air quality concern associated with the works is the potential for generation of dust. The following procedures shall be used to prevent dust generation:
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Application of water sprays during all stages of waste removal and processing.
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The floor of the processing area will be concrete (enabling easy cleaning if required) and a 3 m high dust fence will be erected around it.
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Unsealed support zone roads will be topped with clean granular aggregate sealed with “Lignosite” of other approved dust suppressant.
Vapours
During the waste removal works there is the potential for generation of toxic vapours. Mitigation measures such as water sprays will be applied to reduce the offsite discharge of vapours. Continuous vapour monitoring will be undertaken during the remediation works program.
Odours
The remedial works may result in generation of odours which may be transmitted offsite downwind of the remediation works area and could potentially result in a nuisance for surrounding properties. However, the immediate surroundings of the site are rural, with the nearest dwelling to the site 500 m away, and as such, odour issues are not likely to be a problem.
If significant odour is generated, an odour suppressant may be applied onsite as required.
Noise
All activities will be governed by the requirements of “NZS 6803P: 1999 “Acoustics - Construction Noise”.
Spill Contingency Measures
In the event that mitigation measures are unable to adequately control a potential impact due to extreme weather conditions or if an uncontrolled incident were to occur, the following contingency measures are proposed to ensure that any impacts are managed correctly.
Spill response plan to be followed in the event that contaminated soils or other hazardous waste is released from a truck on route to disposal/treatment facility. The spill response plan must also address other potential contaminants that could be discharged to land or water, such as fuel. The spill response plan will be prepared by the Remediation Contractor.
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