CAPÍTULO I: EPISTEMOLOGÍA CONSTRUCTIVISTA
4. El impacto de la obra de Kelly en la psicología
• deposit of unauthorised waste
• offensive odours or dust beyond the boundary of the premises
• litter beyond the boundary of the premises • equipment breakdown
• flare or power outage.
The contingency plan must be reviewed after the occurrence of any incident covered by the plan to ascertain the effectiveness of the contingency plan and where, if necessary, it could be further improved.
BPEM requirements to comply with clause 15 (3) and (4) of the Landfill WMP
CONTINGENCY PLANNING
Relevant BPEM objectives
To ensure that all potential incidents are considered and that appropriate measures are planned to deal with them.
Required outcomes of the BPEM
• A contingency plan is in place
• All likely impacts are covered in the preparation of the contingency plan.
• All staff are trained in the implementation of the contingency plan.
Suggested measures of the BPEM
• Review the document after any incidents covered by the plan.
7.11 Management of chemicals and fuels
Landfill operations may use a variety of chemicals and fuels. If these are inappropriately managed they can impact adversely on the environment.
The storage and handling of flammable and combustible liquids should be in accordance with the provisions of AS 1940– 2004 The storage and handling of flammable and combustible liquids and Bunding guidelines (EPA publication 347).
BPEM requirements to comply with clause 15 (3) and (4) of the Landfill WMP
MANAGEMENT OF CHEMICALS AND FUEL
Relevant BPEM Objective
To manage the storage and handling of chemicals and fuels so as to minimise the risk of impact on the environment.
Required outcomes of the BPEM
• Storage and handling flammable and combustible liquids in accordance with the provisions of the AS 1940–2004 ‘The storage and handling of flammable and combustible liquids’.
Suggested measures of the BPEM
• Keep onsite chemical and fuel inventories to a minimum. • Construct bunds for liquid storage areas in accordance with
the appropriate regulatory guidelines and/or standards. • Locate storage areas away from waterways or areas
prone to flooding.
• Implement a contingency plan to handle spills to avoid environmental damage.
Particular measures include keeping inventories to a minimum, bunding liquid storage areas and locating them away from waterways or areas prone to flooding, and having a contingency plan for the management of any spills as part of the site environment management system.
7.12 Disease vector control
Flies, mosquitoes, rats, cats and birds (typical disease vectors) are attracted by food wastes and still waters at landfills. If uncontrolled, these pests can affect public health and surrounding ecosystems.
The main mechanisms for the control of disease vectors are the use of cover material to cover waste daily (see section 7.7) and eliminating any waterbodies that are not required for fire, sediment and leachate control. Other measures, such as scare devices and traps, can also be used to reduce or control infestations.
Professional pest exterminators should be employed to reduce problem infestations of vermin.
Landfills located near airports, close to a surface water supply, or industrial or residential areas that may be affected by bird droppings, need a high level of bird control.
The most successful bird-deterrent strategies rely on a variety of techniques. While the immediate spreading of cover material over the wastes may not entirely deter birds, it can be supplemented with other options, such as nets or monofilament wires over glide-paths or water dams, anti- perch strips on buildings, and active measures such as acoustic bird-scaring devices (gas guns or mimicking distress calls), predator decoys or even using dogs.
Since birds become accustomed to one particular measure, some variation in the active measures used is necessary.
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BPEM requirements to comply with clause 15 (3) and (4) of the Landfill WMP
DISEASE VECTOR CONTROL
Relevant BPEM objective
To minimise disease vectors emanating from the landfill by denying pests food and shelter.
Required outcome of the BPEM
• Cover waste daily.
Suggested measures of the BPEM
• Elimination of any waterbodies at the landfill that are not required for fire, sediment or leachate control.
• Use professional pest exterminators to reduce problem infestations of vermin.
• Vary bird scare methods to avoid any patterns in methods.
7.13 Noxious weed control
Once noxious weeds become established at a landfill, they can spread through surrounding areas and adversely impact farming activities and natural ecosystems. Noxious weeds can become established through colonisation or through introduction by contaminated seed or weed-infested mulch used to revegetate exposed areas of earth. To minimise the risk of introducing weeds through planting, only high-quality seed, free from any noxious weeds, should be used.
Where an area is to be mulched, ensure that the mulch is free of noxious weeds. Where the site accepts green waste to be subsequently used for mulching, a degree of diligence is required to prevent noxious weeds from being added to the green waste heap. Such waste should be landfilled.
Any noxious weeds onsite should be managed by regularly inspecting the site for noxious weeds and eradicating any weeds present through appropriate means.
BPEM requirements to comply with clause 15 (3) and (4) of the Landfill WMP
NOXIOUS WEED CONTROL
Relevant BPEM objective
To manage the landfill site so that it does not become a source of noxious weeds.
Required outcomes of the BPEM
• Minimise the introduction of noxious weeds to the site. • Eradicate any noxious weeds that have established
themselves onsite.
Suggested measures of the BPEM
• Ensure that all plantings from seed are from only high- quality seed. Mulch should be completely free of weeds. • Regular inspection of the site for the presence of noxious
weeds. Record their presence and, if necessary, implement a control program.
• Where pest plants need eradication, this is to be done by appropriate means. If the problem is large or current methods are not working, seek the advice of the local council or the Department of Sustainability and Environment.
• Become involved in the local Landcare group to develop regional strategies to eradicate regional noxious weeds.
7.14 Performance monitoring and reporting
In order to assess the performance of the measures taken to protect the environment from any potential
environmental impacts by the landfill, monitoring, assessment and reporting of the results are required. EPA’s requirements for monitoring and auditing are detailed in Landfill licensing guidelines (EPA publication 1323) and submission of annual performance statements are given in Annual performance statement guidelines (EPA publication 1320).
BPEM requirements to comply with clause 15 (3) and (4) of the Landfill WMP
PERFORMANCE MONITORING AND REPORTING
Relevant BPEM objective
To monitor and report on the performance of measures taken to protect the environment from potential impacts from a landfill and to identify and address any arising environmental issues.
Required outcomes of the BPEM
• Preparation of a verified monitoring program in accordance with Landfill licensing guidelines (EPA publication 1323).
• Monitoring of the environment in accordance with the verified monitoring program.
• Submission of an annual performance statement.
Suggested measures of the BPEM
• Develop a workplace culture of identifying any potential environmental issues and taking corrective action before any impacts occur.
• Incorporate into the environment management system both on and offsite inspections by staff to check on any emerging environmental problems or the effectiveness of existing controls.
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8
Best-practice rehabilitation and
aftercare
Many of the chronic impacts of landfilling occur long after the landfill has closed. While these impacts can be mitigated by good design and operation, best-practice rehabilitation and long-term aftercare of the site will further minimise the potential of any detrimental impacts from the landfill.
Best practice for rehabilitation and aftercare is
considered very early in the design and operation phase of the landfill. This section of the Landfill BPEM applies to all existing landfills and closed sites.
8.1 Rehabilitation
8.1.1 Rehabilitation plan
To ensure that the objectives of rehabilitation are achieved, a conceptual rehabilitation plan must be developed as part of the initial landfill design.
The rehabilitation plan should deal with afteruse options for the site and provide a blueprint for the final surface contours and cap design of the landfill.
The rehabilitation plan should include:
• the potential afteruses of the site, taking into
consideration current and likely future land use in the area surrounding the site
• operational requirements, to ensure that the capping is designed to suit the intended afteruse
• surface contours before and after settlement • specifications and materials to be used in the final cap • preservation/installation of environment performance
control or monitoring features.
8.1.2 Progressive rehabilitation
Progressive rehabilitation of a landfill involves the closure and rehabilitation of each cell once filling has been completed during the operating life of the landfill. These works are effectively a staged closure of the landfill that occurs while the active cell is being filled.
Landfill cell rehabilitation works include: • capping and revegetation in accordance with
regulatory requirements
• installation and ongoing maintenance and replacement of gas and leachate collection infrastructure
• decommissioning of infrastructure no longer required. Environmental and management benefits of progressive rehabilitation include:
• collection and treatment of landfill gas during its peak generation period
• minimising the generation of leachate and offensive odours
• facilitating materials budgeting through the staged use of capping materials over the life of the landfill
• achieving cost recovery during the economic life of the landfill
• meeting financial assurance requirements.
8.1.3 Triggers for rehabilitation
Implementation of the progressive rehabilitation at a landfill should be consistent with the conceptual rehabilitation plan prepared during the initial landfill design. A landfill licence-holder should, where operationally practicable, sequence operations to complete the filling of each cell in turn, rather than leaving one or more partly filled cells inactive and not fully rehabilitated.
Where cells cannot be fully rehabilitated due to the layout of the site and the sequencing of filling, intermediate (temporary) capping must be installed.
In order to take best advantage of its inherent benefits, rehabilitation of a landfill cell should be initiated once: • the landfill cell contents have reached the approved
pre-settlement contours, allowing sufficient height to build the landfill capping within the pre-settlement contours
• further filling of the cell is operationally no longer required or feasible
• there has been a lawful direction to cease filling the cell
• the landfill is to be closed or
• two years have elapsed since commencement of filling.
8.1.4 Site afteruse
In considering options for the use of the site after landfilling, the location of the landfill, needs of the local community, surrounding land uses and nature of the operation should all be considered. The relevant
regulatory and planning authorities should be consulted, as they might have a strategic plan for the area that identifies how that land could potentially be used. Proposals for the use of the filled landfill site should be flexible enough to allow for changes in community attitudes or planning requirements in the long period between commencement of landfilling and final rehabilitation.
Regular reviews of afteruse options are a good way of ensuring that the operation of the landfill does not alienate desired afteruses of the site. Understanding the afteruse during operation ensures that the final surface profile of the landfill is consistent with the desired afteruse.
For example, final landforms comprised entirely of steep slopes are generally inconsistent with public open-space use.
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Common afteruses of landfills include sports grounds, public open space and golf courses. Closed landfill are not suitable sites for building or structures, as landfill gas emitted from the cap presents a safety risk and the capping of a landfill is not a stable platform to build on. Historically, some landfills have been developed for commercial or industrial building development.
Developments on landfill sites should only occur after an assessment that the landfill site no longer presents a risk. This will require complete risk assessment of the risks of landfill gas and the impacts of settlement on buildings and services such as water mains, gas and roads.
Closed landfills are considered to be contaminated sites and any end-use developments — including development of land in the surrounding buffer area — will require assessment by an EPA-appointed auditor.
Water features, such as ornamental lakes or ponds, should be avoided on landfills, as they may leak due to cracking of their liner from differential settlement of the landfill over time. This leakage may release significant volumes of water to the landfill, thus generating significant volumes of leachate.
8.1.5 Settlement and final surface profile
A landfill is subject to long-term settlement, as waste decomposes and consolidates. This settlement has significant impacts on the final surface profile, the landfill cap and potential afteruses for the site.
The rate and degree of settlement are dependent upon: • proportion of putrescible wastes
• thickness of the landfill
• period over which wastes were placed in cell • the degree of compaction
• the moisture content of the wastes
• the degree of surcharging or loading placed on the cap. Long-term settlements for well-compacted landfills vary significantly and can range from 10 to 30 per cent. Most of the settlement occurs within the first few years of the cell closure, the result of waste compressing under its own weight and the weight of the cap. After this initial compression, settlement will continue for many years, as a result of consolidation and biodegradation processes within the waste.
A landfill receiving largely non-putrescible wastes will have a lower range of settlement. Where landfill cells are filled rapidly, the settlement of the closed landfill will be higher than for an equivalent thickness of wastes placed over a longer period.
The landfill cap design is governed by limiting water infiltration into the landfill and gas migration through the cap; these are a function of the materials used in the cap and its shape. The gradient for a completed cap should be sufficient to prevent water ponding on the cap to
minimise infiltration through the cap. Gradients of about five per cent will adequately shed water.
Where the proposed after use of the landfill require a gradient of less than 5% the cap design may need to incorporate additional levels of protection. Cap gradients of less than 1% are likely to have issues with water ponding in areas of differential settlement.
Caps should not be steeper than 20%. Caps steeper than this can have erosion problems and are more difficult to maintain than flatter caps. Steep caps will require specific engineering controls to ensure that they are stable. These controls will, typically, relate to relieving any seepage water pressures within the cap. They will also require features such as cut-off drains and rock beaching on drainage lines to control water erosion. In addition, the surface layer should be vegetated as quickly as possible to further control erosion. Until the vegetation becomes established, this revegetation program should be
augmented with measures such as mulch or erosion mats to control erosion.
Since compaction of wastes along near-vertical side walls is difficult, the wastes along the walls of the landfill may exhibit the highest initial rate of settlement. The landfill cap needs to make allowance for this by providing sufficient thickness of the cap to ensure that run-off from the cap is not collected in depressions along the
perimeter of the landfilled area.
The landfill aftercare program must include inspections of the cap, checking for differential settlement and
indicators that the integrity of the low-permeability cap has been compromised. The frequency of the inspection program will be largely determined from the observed rate of settlement.
The use of plants on the landfill caps must consider the particular requirements of the cap design, and vegetation used must be compatible with the cap design.
Conventional caps require plant roots not to penetrate the barrier layer underlying the topsoil layer. Phytocaps use different principles than conventional caps and require different vegetation strategies (see section 8.1.7 for further information).
8.1.6 Landfill cap
A key element of the rehabilitation is the capping of the landfill. The design objectives for the final landfill surface or capping are:
• minimising infiltration of water into the waste, ensuring that the infiltration rate does not exceed the seepage rate through base of the landfill
• providing a long-term stable barrier between waste and the environment in order to protect human health and the environment
• preventing the uncontrolled escape of landfill gas • providing land suitable for its intended afteruse.