Taking the analogy of ancient Greek philosophers, the environmental management of any industry must examine in part or in detail the five basic elements of nature: water, air, earth, fire and aether.
Water management in Australia is vital for many extractive operations? survival. Proper design controls should be in place to maintain the appropriate balance between harvesting for operational uses (dust suppression and processing), in conjunction with separation of excess water through installation of devices that divert clean water around the operation to prevent dam overloading.
Air quality for all quarries is basically the management of dust that is emitted from the site. Poor planning can create large areas of disturbed dusty surfaces that are quickly swept into dust clouds in high wind periods. We all know that a water cart will not win in high winds on a bull dust surface! Quarry operators must consider their location with regard to prevailing winds and local neighbours. Minimising the amount of disturbed surfaces and careful quarry planning with regard to progressive stripping and rehabilitation can reduce the amount of these disturbed surfaces.
The earth element in this analogy is geology and geography. Geology forms the basis of the raw materials quarries extract as well as the soil constituents that must be used to assist with the ongoing rehabilitation. Geography is the landscape of the surrounding area of the quarry as well as the interaction with local community, ie your neighbours.
Fire management is not always considered one of the major elements of a quarry?s function but consideration should be given to the role of quarries in fire emergency situations, such as bushfires and spontaneous combustion, and how management can assist the fire services.
Aether was considered to be the stuff that the gods breathed, not air as mere mortals do. In this context, perhaps we can consider government authorities such as local councils, the Environmental Protection Agency (EPA), the Department of Planning, the Department of Environment and Climate Change, and the Department of Primary Industries as the ?gods? that we must pay homage to!
To discuss water generally across Australia is virtually impossible but the basic principles of harvesting and diversion apply everywhere. Quarry operators must evaluate their water consumption requirements and then, based upon average rainfall data (and possible evaporation rates), determine how much needs to be harvested and how much clean water needs to be diverted.
If dirty water is required to be discharged then tests should be undertaken to ensure it meets your prescribed water guidelines. All operators must ensure that they do nonimpact on or alter the downstream water quality. Quality guidelines will vary depending upon your catchment and downstream water uses. Electrical conductivity, pH and total suspended solids or turbidity are typical tests for assessing the water quality. Up and downstream samples can also assist in deciding whether your operation is blending into the local environment.
Acidity and alkalinity of the water is measured by pH. The pH of acid water is 1.0, alkaline water is 14 and neutral water has a pH of 7.0. A rough guide of 6.5 to 8.0 is usually within the Australian and New Zealand Environment and Conservation Council (ANZECC) Guidelines for Aquatic Ecosystems, but to be sure, check with your local EPA office.
Conductivity is a measure of dissolved salts or salinity, and is measured in micro Siemens per centimetre (?Scm-1). Fresh drinking water is up to around 700 ?Scm-1, 11,000 ?Scm-1 will kill couch grass, and ocean salt water is around 10,000 to 15,000 ?Scm-1.
Total suspended solids is a measure of the amount of solid, sediment particles in the water. Values over 50mg per litre typically require some treatment. Turbidity is the measurement of the amount of light that can pass through the water. It is usually measured in Nephelometric Turbidity Units (NTU) and values of less than 70 to 100 NTU are generally acceptable.
Airborne particles can cause air pollution, a major environmental issue affecting people?s health, visibility and climate.
There are three main ways of measuring air pollution, ranging from non-automatic, semi-automatic and automatic utilising simple physical and chemical techniques or more sophisticated electronic techniques. Non-automatic monitoring methods are generally cheaper and easier to operate but do not give as much accuracy or resolution as automatic methods.
This type of monitoring is also known as passive sampling which can take several forms, depending on the analyst, of interest and environment.
By far the most common form of passive sampling in the quarry industry is the use of static dust gauge monitoring to investigate particulate matter made up of predominantly dust particles which, because of their size, rapidly settle from the air. This dust can be a nuisance by soiling property in the vicinity of its point of emission. This type of sampling can be used to establish long-term trends and to investigate localised dust fall. Some important points to keep in mind when sampling and interpreting static dust gauge results are:
? The level of monitoring is directly related to the number of houses and type of industry around the site. For example, a quarry in a rural setting may have no requirement for dust sampling while a quarry adjacent to a school may have a number of samplers.
? Records of wind speed and direction are important to interpret the results of the sampling, especially when deciding whether dust pollution emanates from your operations or another source.
? The gauges are prone to vandalism and tampering, especially when situated in suburban environments. These should be noted in the sampling report so that any anomalous results can be accounted for.
? Where possible, background dust levels should be taken prior to the commencement of quarrying. This will help the operator determine how his operations have impacted the local environment.
This group of samplers is often referred to as active samplers and typically involve pumping a known volume of air through a collection medium for further analysis. Samples can be taken each day, thereby providing measurements for shorter periods of time, but at a relatively low capital cost compared with automatic monitoring methods. High Volume Air Sampling (HVAS) is one example of an active sampling technique familiar to many quarry operators. Automatic sampling
Automatic sampling or continuous sampling is used when a higher degree of accuracy is needed and a greater risk of harm to the environment may be involved. The equipment may be highly technical and expensive to run and monitor. The advantage is that results are available in real time. The technique can be applied to dust monitoring using either conventional collection mediums or optical measurements.
Management of dust
Dust management in general is common sense. Use of water carts will assist in the reduction of dust during extraction and hauling operations and operations should cease when excessive wind (eg >36 kph) is experienced. Vehicle movements should be kept to a minimum to avoid unnecessary dust generation. Revegetation of disturbed areas whether final or temporary will also reduce the areas prone to nuisance dust.
Daily monitoring of wind speed and direction is a useful guide to assessing whether quarry activities are likely to have adverse effects on neighbouring residents. The process can be as sophisticated and expensive as online weather stations with alarms activated when wind speed and direction exceed specified limits, or as simple as a nominated person to use a hand-held anemometer to record wind speed and direction at certain times during the day. Visual assessments should be made when changes in the weather occur.
The source rocks for quarries vary from site to site but typically include hard rock varieties such as basalt, conglomerate, andesite, granite, and quartzite and softer rocks (ie less consolidated) including sand, gravel, clay and soil. These are extracted and processed, if required, and trucked to customers.
The weathered zone of these deposits or upper most 0.5 metres is made up of the soil profile, which contains leached components of the source rock below as well as some nutrients resulting from thousands of years of vegetation overlying the weathering bedrock.
Soil layers or profiles are important for the successful regeneration of the site. The top-most layer contains a valuable seedbank which can provide free vegetation for rehabilitation if stored and re-used correctly. Lower soil profiles from closer to the bedrock are generally less fertile and will require soil supplements to promote effective growth. Best practice is to strip and store these layers separately, then replace over finished faces as the same layers, allowing the seedbank the greatest chance of regeneration with minimal outside assistance.
The local surrounding environment can play a great role in the life of a quarry and good operators are sensitive to these issues which include the local community, upstream catchment activities, downstream uses and their immediate neighbours. Solid, open and consistent interaction with your local community can assist by taking the mystery out of what you are doing, and being involved in local community programmes shows your industry cares about the area in which it operates.
Appropriate fire management plans are recommended and should be part of the quarry safety plans. The basic element of fire management is to liaise with the local fire authorities, and determine whether you would be visited by your State fire brigade or the rural fire services. Organise a site visit so they can review your site, make sure they have keys to locks on gates in case of emergencies and also get them to assess your fuel potential in the surrounding bush areas. Sometimes a controlled burn can also be arranged as part of an exercise to reduce fuel near houses and practice for the local fire services. Ensure they are aware of the location of dams and overburden stockpiles that can be used in fire fighting.
In any quarry operation, consent must be obtained from the appropriate government authorities (?Gods?) prior to works commencing. It pays to ensure your quarry plan encompasses realistic goals as far as extraction and rehabilitation activities are concerned in order to avoid costly mistakes and remediation later. Liaison with consent authorities and other stakeholders will assist in reaching mutually agreeable outcomes.
A detailed plan of management and ongoing annual reporting of site activities are often an important consent condition applied to quarries. These can provide a platform for communicating to authorities your good work as far as monitoring and rehabilitation activities, and outlining future intentions or changes to the original plan.
Greg Thomson is the principal consulting geologist for VGT Environmental Solutions