4.0 Predicted Environmental Impacts and Mitigation Measures

Transcription

1 4.0 Predicted Environmental Impacts and Mitigation Measures 4.1 Introduction This chapter deals with the expected impacts and the respective mitigation measures of the project to the environment during construction, operational and decommissioning stages. It indicates the level up to which the proposed plant will benefit the site area in view of preventing adverse environmental impacts. 4.2 Stages and Impacts Considered An Environmental Impact Analysis has been carried out whereby all the possible environmental, socio economic and safety and health aspects and their respective impacts have been considered. The entire project cycle has been analyzed over the following stages (or activities): Construction Operation Decommissioning The impact categories analyzed were: Greenhouse gas emissions Energy consumption Freshwater resources Marine and terrestrial ecosystem Social and cultural issues Land use planning and management Storage and use of harmful substances Air quality, noise and odour Wastewater Solid waste Safety and health hazards 4.3 Outcome of the Environmental Impact Analysis The outcome of this exercise is presented in Table 4.1. Activities that could potentially cause significant environmental impacts have been singled out as those that need further investigation to ascertain the level of environmental stress that they may cause. The aspects that could possibly have a significant impact on the environment have been retained for further analysis. 34

2 Stage Type (E, SE, H&S) N/P Severity Likelihood Significance Table 4.1: Environmental, Socio Economic and Safety Aspects and Impacts Aspect/Activity Impact Level of Significance 1 Construction Phase: Construction of the scrap tyre/rubber and plastic pyrolysis plant 2 Operation Phase: Operation of scrap tyre/rubber and plastic pyrolysis plant Greenhouse Gas Emissions E N Relatively Harmless Energy Consumption E N Relatively Harmless Freshwater Consumption E N Relatively Harmless Marine and Terrestrial Ecosystem Socio-Cultural and Economic Issues SE P Relatively Harmless Land Use Planning and Management E &SE N Relatively Harmless Storage and Use of Harmful Substances Air Quality, Noise and Odour E, SE & H&S N Mild Effect, Easily Correctable Wastewater Generation E N Relatively Harmless Solid Waste Generation E N Mild Effect, Easily Correctable Safety and Health Hazards H&S N Relatively Harmless Greenhouse Gas Emissions E N Relatively Harmless Energy Consumption E N Mild Effect, Easily Correctable Freshwater Consumption E N Mild Effect, Easily Correctable Marine and Terrestrial Ecosystem Socio-Cultural and Economic Issues SE P Relatively Harmless Land Use Planning and Management E &SE N Relatively Harmless Storage of Scrap Tyres and Waste Plastic E & H&S N Mild Effect, Easily Correctable Air Quality, Noise and Odour E, SE & H&S N Harmful but Correctable Wastewater Generation E N Harmful but Correctable Solid Waste Generation E N Relatively Harmless Safety and Health Hazards H&S N Mild Effect, Easily Correctable 35

3 Stage Type (E, SE, H&S) N/P Severity Likelihood Significance Aspect/Activity Impact Level of Significance 3 Decommissioning Phase: Disposal of solid wastes to landfill; Sending toxic materials (used oil and lubricants) to recycling or reuse facilities. Greenhouse Gas Emissions Energy Consumption Freshwater Consumption Marine and Terrestrial Ecosystem Socio-Cultural and Economic Issues Land Use Planning and Management E &SE N Relatively Harmless Storage and Use of Harmful Substances E & H&S N Relatively Harmless Air Quality, Noise and Odour E, SE & H&S N Relatively Harmless Wastewater Generation Solid Waste Generation E N Mild Effect, Easily Correctable Safety and Health Hazards H&S N Relatively Harmless 36

4 Severity to 25 Requires Immediate Action to 20 Harmful but Correctable to 9 Mild Effect, Easily Correctable to 4 Relatively Harmless Likelihood Severity Likelihood 1 No Impact 1 Very Improbable 2 Negligible Impact 2 Not Probable 3 Considerable Impact 3 Rarely Occurring 4 Great Impact 4 From Time to Time 5 Very Great Impact 5 Fairly Regularly E- Environmental Impact N- Negative Impact S- Safety Impact P- Positive Impact SE- Socio Economic Impact 37

5 4.3.1 Noise and Dust Generation during Construction Level of Significance: 8 (Mild Effect, Easily Correctable) Aspect/Activity: Air Quality and Noise Generation Negative Environmental Impact: It is expected that the use of heavy machinery during construction works will give rise to some noise and dust pollution which unless mitigated can become an environmental nuisance. The construction activities will consist of: Site preparation excavation by cutting and filling to form a site platform; Erection of the scrap tyre/waste plastic pyrolysis plant and associated facilities; Construction of the office building. The activities mentioned will be the main source of noise and dust. The promoter will ensure that construction works are not carried out during undue hours or at night time. The site will be enclosed to avoid causing dust nuisance to the surrounding environment. It will be regularly sprayed with water to minimize dust generation onsite. There will be no nuisance caused by dust and noise to the neighbourhood, due to the absence of inhabitants in the immediate vicinity of the site. The noise level will be within prescribed limits of neighbourhood noise according to the Environmental Protection (Environmental Standards for Noise) Regulations 1997 as shown in Table 4.2. Table 4.2: Neighbourhood Noise Exposure Limits 07:00 18:00 hrs 60 db(a) L eq 18:00 21:00 hrs 55 db(a) L eq 21:00 07:00 hrs 50 db(a) L eq Emissions from machines will be in line with the Emission Standards (see Table 2.1) and Ambient Air Quality Standards (see Table 2.2) in force in Mauritius as per the Environmental Protection (Standards for Air) Regulations

6 4.3.2 Solid Waste Production during Construction Level of Significance: 6 (Mild Effect, Easily Correctable) Aspect/Activity: Solid Waste Generation Negative Environmental Impact: It is expected that the construction phase will produce solid waste (construction and domestic wastes), which unless mitigated can become an environmental nuisance and be source of eyesore. Construction wastes will comprise excavated materials, general construction wastes like wood, scrap metal and concrete, chemical wastes from servicing/maintenance of machineries and waste from site workers. The 15 workers onsite will generate around 14 kg domestic waste daily assuming that 0.9 kg per day domestic waste is produced per worker. The remaining amount of construction wastes is expected to be approximately 1,000 kg/day. The site boundary will be closed with a compound enclosure wall, hence reducing visual impacts to the surroundings. The quantity of waste materials arising from the construction phase is not expected to be high as most of the construction waste will be used as backfill. Designated containers for the disposal of domestic solid waste will be provided onsite and these would be sent to Mare Chicose landfill by a licensed waste carrier. All practical measures will be taken to avoid and minimize wastes to be landfilled by waste segregation and recycling. A separate area will be designated for storage and monitoring of toxic wastes, like used oil (as per Annex 6C). They will be collected in drums to be sent for recycling by a licensed carrier Energy Consumption during Operation Level of Significance: 5 (Mild Effect, Easily Correctable) Aspect/Activity: Energy Consumption Negative Environmental Impact: Electricity consumed during the operation phase has been estimated at 200 kwh on a daily basis for the two implementation phases of the project. 39

7 The detailed power requirement for the machinery to be used onsite is found in section No mitigation measures are necessary as this is not an excessive quantity that will affect power supply in the region Water Consumption during Operation Level of Significance: 5 (Mild Effect, Easily Correctable) Aspect/Activity: Freshwater Resource Consumption Negative Environmental Impact: Given that the number of employees during operation to be 10 and that the rate of consumption if at 162 litres per day per person, the workers will be requiring approximately 1.6 m 3 per day of water. Water storage should allow for two days of water supply, hence a reservoir of around 4 m 3 capacity has to be provided. The emission control equipment (wet scrubber) will have a water consumption of 0.7 m 3 /day. The facility will be consuming water at around 1.6 m 3 per day and the wet scrubber will have a makeup water requirement of 0.2 m 3 /day (30% of water consumed). Hence, no mitigation measure is required as this is not considered to be an excessive quantity Opportunity for Employment Creation during Operation Level of Significance: 1 (Relatively Harmless) Aspect/Activity: Socio-Cultural and Economic Issues Positive Socio-Economic Impact: The project is expected to create direct employment for around 10 people. During operation of the plant, the type of jobs created will be as follow: 40

8 For collection and transportation of scrap tyre and plastic: Lorry drivers Scrap tyre and plastic collectors For operation of the pyrolysis plant: Plant manager Engineers Process operators Electricians Mechanics Chemists Administrative officers Cleaners Creation of employment is a positive impact; therefore no mitigation measure is necessary Risks Associated with Storage of Scrap Tyres and Waste Plastics Level of Significance: 6 (Mild Effect, Easily Correctable) Aspect/Activity: Storage of Scrap Tyres and Waste Plastic Negative Environmental and Health & Safety Impact: The pyrolysis plant will be functioning in semi continuous process; hence storage of the raw materials (waste tyres and plastics) will be required. In this regard, the risks associated to the storage of scrap tyres and plastics have been considered. The major impacts linked with tyre storage are as discussed below: Risk of tyre fires Tyre fires are severe potential environmental impacts. When they burn in the open air, the tyres combust incompletely and produce air pollution. The latter comprise conventional air pollutants like particulates, carbon monoxide, sulphur oxides, nitrogen oxides and volatile organic compounds and hazardous pollutants like Polycyclic Aromatic Hydrocarbons (PAHs), dioxins, furans, hydrogen chloride, benzene, polychlorinated biphenyles (PCBs) and heavy metals (lead 41

9 and arsenic). Consequently, short and long term health problems such as skin and eye irritation, cancer, depression and nervous system ailments may be created. Risk of tyre leachate contaminating groundwater, surface water and soil Tyre leachate will be dependent upon factors like tyre size, amount of steel exposed, chemical environment, permeability of soil, distance to groundwater table, distance from tyre storage site, contact time with water, vertical water flow through soil, horizontal groundwater flow and leachate compounds at site. Risk with health consequences Improper storage of tyres may become a potential breeding ground for mosquitoes, rodents and other animals. These living organisms, when infected may transmit diseases to humans. The major risk associated with waste plastic storage, when not properly stored, is the risk of transmission of diseases due to accumulation of water. Plastic may also be source of land pollution if stored in the open and may fly away during windy weather. The designated tyre storage area will be on level site away from surface watercourses, flood zones and groundwater recharge points as per EPA Guidelines of South Australia (2010). The area will have a concrete flooring to eliminate the risk of contamination due to leachate. Flammable or combustible liquids and ignitable materials will not be stored near to tyre stockpiles. The facility will accommodate around 50 MT of tyres with a storage capacity for 6 days. The stockpile will be arranged in a neat manner. A specific area will be designated for the storage of waste plastics to limit its impact to the environment. The area will be covered to protect the waste against rainfall, thus eliminating the risk of water accumulation. Hence, the risk of mosquito proliferation will be eradicated. The storage facility will also be enclosed for protection against prevailing wind. Therefore the risk of plastics flying away from site will be reduced. 42

10 4.3.7 Flue Gas Emission and Noise Generation during Operation Flue Gas Emission Flue Gas Emission Level of Significance: 12 (Harmful but Correctable) Aspect/Activity: Air Quality Negative Environmental and Health & Safety Impact: In the pyrolysis plant, the pyrolysis reactor will not contribute to GHG emissions as it does not require oxygen, thus does not produce CO 2. Also, since the wastes do not comprise halogens as shown in Table 4.3 and 4.4, there will be no production of hazardous emissions like dioxins and furans. Production of hydrogen chloride (HCl) is avoided by the absence of polyvinyl chlorine (PVC) in the mixed plastic waste. However, there will be generation of particulates due to the composition of tyre (see Figure 4.1) consisting of rubber, carbon black, metal, textile, zinc oxide, sulphur and additives. Particulate matter (PM 10 ) will comprise carbon black, sulphur, zinc oxide, clay filler, calcium carbonate, magnesium carbonate and silicates (EPA, 1991). Table 4.3: Composition of Tyre Material Car Tyre (%) Truck Tyre (%) Rubber / Elastomers Carbon Black Metal Textile Zinc Oxide 1 2 Sulphur 1 1 Additives Source: MWH, 2004 Table 4.4: Composition of Mixed Plastic Material High Density Polyethylene (HDPE) Low Density Polyethylene (LDPE) Polyethylene (PE) Polyethylene Terephthalate (PET) Polypropylene (PP) Polystyrene (PS) Chemical Formula (C 2 H 4 ) n (C 2 H 4 ) n (C 2 H 4 ) n (C 10 H 8 O 4 ) n (C 3 H 6 ) n (C 8 H 8 ) n 43

11 Figure 4.1: Component of Tyre Source: Evans, 2006 The pyrolysis units are expected to have minimal air pollution impacts because most of the pyrolysis gas generated in the pyrolysis process will be burned as fuel in the process. During burning, the organic compounds will be destroyed. Assuming complete combustion, the products will be water, carbon dioxide, oxygen and nitrogen from excess air, and hydrogen from pyrolysis gas. Nitrous oxides are expected to be produced at temperatures above 1,300 o C (EPA, 1999), but since the process takes place below 760 o C, no NO x will be generated. 44

12 Table 4.5 shows the typical composition of pyrolytic gas used for energy recovery in the gas burner for the scrap tyre pyrolysis unit. Table 4.5: Gas Composition from the Pyrolysis of Scrap Tyre Constituent Volume Percent (%) Density (kg/m 3 ) Weight Percent (%) Hydrogen Methane Ethane Propane Propylene Isobutylene Isobutane Butane Butene Trans-Butene Iso-butene-2 trace Source: EPA, 1991 Table 4.6 shows the typical composition of pyrolytic gas used for energy recovery in the gas burner for the waste plastic pyrolysis unit. Table 4.6: Gas Composition from the Pyrolysis of Mixed Plastic Constituent Weight Percent (%) Hydrogen 0.22 Methane 2.87 Ethane 3.39 Ethene 5.65 Propane 1.26 Propene 5.53 Butane 6.35 Butene 0.24 Source: William, 2006 The pyrolysis reactor will have emissions which unless mitigated may cause environmental nuisances. A wet scrubber will be used which will minimise the impacts of emissions to the environment. 45

13 Wet Scrubbing Wetted packed towers are the simplest and most commonly used approaches to gas scrubbing. The principle of this type of scrubber is to remove contaminants (NO X, SO X, fly ash, particulate matter) from the gas stream by passing the stream through a packed structure which provides a large wetted surface area to induce intimate contact between the gas and the scrubbing liquor. The contaminant is absorbed into or reacted with the scrubbing liquor. The packing of the tower is normally a proprietary loose fill random packing designed to encourage dispersion of the liquid flow without tracking, to provide maximum contact area for the 'mass transfer' interaction and to offer minimal back pressure to the gas flow. The reactivity between the contaminant and the scrubbing liquor influences the system designer's determination of gas and liquor flow and the height and diameter of the packed bed. A demister is fitted at the top of the tower to prevent entrainment of droplets of the scrubbing liquor into the extraction system or stack. Figure 4.2 below shows an example of a wet scrubber installed in a rubber tyre pyrolysis plant in South Africa. Figure 4.2: Wet Scrubber System 46

14 Fugitive emissions will comprise volatile organic compounds (VOC). It is considered that for 100 MT of tyres per day, 50 kg of VOC (EPA, 1991) are emitted. Therefore it is estimated that the plant (5 MT/day) will have about 2.5 kg/day of VOC. The latter will be reduced with good supervision and good maintenance practices, good training of personnel and use of specific components (pumps, valves and compressors) Noise Generation Level of Significance: 12 (Harmful but Correctable) Aspect/Activity: Noise Generation Negative Environmental and Health & Safety Impact: The plant will give rise to noise which unless mitigated can become an environmental nuisance. The promoter will ensure that works are not carried out during undue hours or at night time. It is expected that equipment like shredder (72 dba), valves (85-90 dba) and pumps (<85 dba) will be the main sources of noise within the factory. The expected noise level at 500 m and 1000 m will be 58 dba and 45 dba respectively. The noise level will be within prescribed limits of industrial noise according to the Environment Protection (Environmental Standards for Noise) Regulations 1997 as shown in Table 4.7. The pyrolysis plant will be operated 12 hours daily, hence disturbance due to noise is not expected during undue hours or at night. Table 4.7: Industrial Noise Exposure Limits 07:00 21:00 hrs 60* db(a) L eq 21:00 07:00 hrs 55* db(a) L eq *Apply to a tonal character adjustment of +5 db(a) to the measured value where the noise has a definite continuous note such as a whine or hiss. 47

15 4.3.8 Wastewater Generation Level of Significance: 12 (Harmful but Correctable) Aspect/Activity: Wastewater Generation Negative Environmental Impact: For calculation of domestic wastewater, given the total number of employees to be 10 during operation, each person may be assumed to consume 162 litres of water per day. Domestic wastewater generation is expected to be 1.3 m 3 per day assuming that 80% of the water consumed ends up as wastewater. Water will be used as the scrubbing liquor in the flue gas cleaning operation. This results in cooling of the gas and triggering the reaction of SO x with water to form ozone and sulphuric acid. This acidic wastewater produced has to be treated. The domestic wastewater (1.3 m 3 /day) from the toilets will be channelled to a manhole for connection to a septic tank and leaching field in accordance with the requirements of the Wastewater Management Authority. The layout plan in Annex 7 shows where the toilets and manholes will be located onsite. The proposed scrubber is of the wet type one. Water is sprayed into scrubber, through nozzles located at the base and the middle of the scrubber. This results in cooling down of the gas and triggering the reaction of SO x with water, to occur H 2 SO 3 and H 2 SO 4. Some chemical foaming agent (having similar properties to a detergent) is injected in the water line going through the dust and fly ash collector. The ph of the water being pumped to the scrubber is adjusted. The reaction tank is supplied with NaOH from the reagent tank. Under normal conditions, Na 2 SO 4 (sodium sulphate) is dissolved (100%) in the water, thus effluent is produced every time until saturation of the solution. The wastewater containing Na 2 SO 4 is then pumped to bag filters. The clean water coming out of the bag filters is then recycled to the spray nozzles of the wet scrubber. This unit is the perfect example of a sustainable technology, as there is resource conservation in terms of water consumption. The particulate solids obtained from the bad filter will then be collected and allowed to dry prior to disposal at the landfill. 48

16 4.3.9 Potential Safety and Health Hazards during Operation Level of Significance: 6 (Mild Effect, Easily Correctable) Aspect/Activity: Safety and Health Hazards Negative Health & Safety Impact: It is expected that the operation of the pyrolysis facility may present potential safety and health hazards due to machines used onsite unless mitigated. All workers will be provided with appropriate personal protective equipment such as protective helmet, gloves, steel-toes shoes; all approved by a safety and health officer. Signboards will be placed in appropriate places on the site to prevent any accidents. Fire extinguishers will also be placed in calculated areas. The access routes shall be well maintained and accessible at all times for emergency vehicles. No open air burning will be allowed within 300 m from storage facility and no welding or other heat generating devices within 60 m (EPA, 2010). A fuel spill contingency plan and emergency preparedness plan have been prepared as per Annex 8 and Annex 9 respectively Metal Waste and other Scrap during Decommissioning Level of Significance: 9 (Mild Effect, Easily Correctable) Aspect/Activity: Solid Waste Generation Negative Environmental Impact: It is envisaged that at the end of the 20 lifetime of the pyrolysis plant, the latter would be decommissioned, which will generate metal waste and other scrap. They will consist of dismantled parts of the plant. Since scrap metal will only degrade slightly in the environment and these wastes would occupy space if land-filled, a better option would be to send the wastes to recycling facilities. Other 49

17 scraps produced from the decommissioning phase will be segregated and will be reused or recycled to reduce the amount of waste disposed at the landfill 50

18 4.15 Summary of Mitigation Measures Table 4.8 represents a summary of the mitigation measures discussed in this chapter. Table 4.8: Summary of Mitigation Measures Activity Aspect Impact Mitigation Measure 1. Construction 2. Operation Noise and dust generation Solid waste production Noise and dust generation from use of heavy machinery 14 kg/day domestic waste Around 1,000 kg/day construction waste Electricity consumption from Around 200 kwh of electricity will - CEB be consumed daily 1.6 m 3 /day of water will be drawn Water consumption from CWA mains and 0.2 m 3 /day - as makeup water to wet scrubber Creation of employment 10 jobs will be created - Risks associated with storage of scrap tyres and waste plastics Risk of tyre fires Risk of tyre leachate contaminating groundwater, surface water and soil Risk of transmission of diseases Civil works will not be carried out during undue hours and night time. Noise will be within prescribed limits for neighbourhood noise exposure limits: 07:00 18:00hrs 60 db(a)l eq 18:00 21:00hrs 55 db(a)l eq 21:0 07:00hrs 50 db(a)l eq Site will be fenced to reduce dust propagation. Site will be sprinkled with water. Construction waste will be used as backfill. Waste will be segregated for recycling and composting. Remaining waste will be sent to landfill. Toxic wastes will be transported by a licensed carrier for recycling. Around 50 MT of tyres will be stored on level site (EPA, 2010). Concrete flooring for storage facility. Combustible or flammable liquid will not be stored near storage area. Plastic storage area should be enclosed and protected against rain and wind. 51

19 2. Operation Activity Aspect Impact Mitigation Measure 3. Decommissioning Flue gas emission Noise generation Wastewater generation Potential safety and health hazards Metal and other scrap No harmful emissions (dioxins and furans) produced Noise generation from factory is expected to be 58 dba and 45 dba at a distance of 500 m and 1000 m respectively 1.3 m 3 /day domestic wastewater generated and m 3 /day wastewater from wet scrubber Risk of accidents and injuries Generated from dismantling of plant Emissions will be in accordance with standards, with <100 µg/m 3 PM % PM removal with wet scrubber. Plant will operate 12 hours per day. Noise generated will be with respect to industrial noise exposure limits, that is: 07:00 21:00 hrs 60 db(a) L eq 21:00 07:00 hrs 55 db(a) L eq Domestic wastewater will be channelled to septic tank and wastewater from wet scrubber will be recycled back PPEs will be provided to workers onsite. Signboards will be placed onsite to avoid risk of accidents. Fire extinguishers will be provided onsite. Access route for emergency vehicles will be well maintained. No burning within 300 m from storage area and no welding within 60 m. Scrap metal will be recycled Other scraps will be segregated for reuse or recycling 52