Ecoengineering 3 PROJECT DESCRIPTION

Transcription

1 BESTCRETE AGGREGATES LIMITED EIA FOR MINING OF SAND AND GRAVEL AT PINE POAD, MATURA 3 PROJECT DESCRIPTION This chapter describes the proposed mining of sand and gravel (pitrun) by Bestcrete Aggregates Limited (BAL) at Pine Road, Matura. It begins with an overview of the project, and then describes: < Mining Reserves, < Mining Operation, < Transport and Processing, < Rehabilitation, < Workforce and Equipment, < Ancillary Facilities, < Utilities, < Waste Management, and < Project Schedule. 3.1 Project Overview In September 2009, Bestcrete Aggregates Limited (BAL) was granted a Quarry License by the Ministry of Energy and Energy Industries (MEEI) {now the Ministry of Energy and Energy Affairs (MEEA)} to conduct quarrying activities on approximately 209 acres of state land within the Melajo Forest Reserve. The proposed quarry site is located within the prolific gravel-bearing Valencia - Matura area. The site is located on Pine Road, which is off the Toco Main Road, Matura, County of St. Andrew/ St. David (see Figure 1-1). It comprises part of the Melajo Forest Reserve, which was planted with pine trees and has been harvested and released for Quarrying by the Forestry Division of the Ministry of Housing and the Environment. The vegetation at present consists of secondary vegetation. The property is surrounded on all sides by State lands of the forest reserve, its northern boundary is defined by the Melajo River, its southern boundary by Pine Road and its eastern boundary by Tractor Road. In view of the depth of the water table estimated at 15 to 20 feet, it is envisaged that the majority of pitrun will be mined dry. The extracted material will be transported by road to an off-site facility where it will be converted to construction materials (sharp sand, 10 mm, 25 mm and 40 mm gravel and ballast) to be used by the company. Ecoengineering 13 of 118 environmentally appropriate development for the Caribbean

2 BESTCRETE AGGREGATES LIMITED EIA FOR MINING OF SAND AND GRAVEL AT PINE POAD, MATURA 3.2 Mining Reserves General Sand and gravel occur naturally along the foothills of the Northern Range. The gravel belt encompasses Wallerfield, Valencia and Matura in the north-east. The sand and gravel deposit consists of a heterogeneous mixture of clay, sand and gravel which grade laterally and vertically into one another. The gravel deposits are associated with impurities (clay and silt) which may comprise 0 % to 40% of the deposit. The major associated sediment types associated with the gravel deposits are as follows: < Overburden generally ranges from 6 inches to 15 feet thick and consists of soil (6 inches to 18 feet thick) and clay. This is removed to expose the underlying commercial deposits. < The interburden may range from 1 foot to 20 feet thick and may comprise the interbedded clay bands that separate individual gravel units or the underlying basal rocks. < A fine, well-sorted white to yellow, pure marine sand is located in some areas along Pine Road and in some areas it is in beds in excess of 8 m thick. < Pitrun occurs as thin beds and lenses overlying the basal clay. Bank pitrun of marine origin occurs on the proposed quarry site Initial Survey Seven boreholes were drilled to a depth of 30 metres by Trintoplan Consultants in February 2010 and the locations are shown in Figure 3-1. The reserves of pitrun are estimated at 1.8 million cu yards or 5 30,000 cu. yd. /month. Cross sections of the site are shown in Figures 3-2, 3-3 and 3-4. The Mine Design Plan is provided in Appendix D. 3.3 Mining Operation The operation at Matura will consist of mining only as no processing will be conducted on the site. The various processes involved in the Mining Operation are as follows: (a) Mobilisation and Site Preparation, (b) Clearing of Vegetation and Overburden, (c) Winning of Gravel Deposits, and (d) Transportation to the Processing Plant. Ecoengineering 14 of 118 environmentally appropriate development for the Caribbean

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11 BESTCRETE AGGREGATES LIMITED EIA FOR MINING OF SAND AND GRAVEL AT PINE POAD, MATURA Mobilisation and Site Preparation It is expected that the mining operation will last approximately five years. A site office will be constructed with concrete blocks and masonry with dimensions roughly 20 feet long x 20 feet wide close to the entrance of the quarry. The site office will serve the following purposes: < Storage for tools, minor equipment and parts; < Offices for company s staff and government s checker; < Lunch room for staff; and < Watchman s quarters. A 30 feet wide access road will be constructed through the site to access the pitrun deposits ensuring that there is a minimum 15 m setback from the Melajo River. The road will be constructed using the Kolbelco SK335 Excavator or equivalent and New Holland D350 Bulldozer or equivalent. A drain (3 feet wide and 3 feet deep) will be constructed on the shoulder of the road to ensure rapid drainage and maintenance of an acceptable surface. Figure 3-5 shows a sketch of the layout for proposed quarry Clearing of Vegetation and Overburden Land clearing will be kept to a minimum, with just enough being cleared to facilitate an efficient mining operation. Based on the geological map, areas underlain by clay will be left undisturbed in their original state, as far as practical. The extraction of pitrun will be conducted in a progressive, organized manner from west to east. The reserves are mainly concentrated in the middle of the site, so not all 209 acres will be cleared. A buffer zone will be left along the Melajo River (15 m) and along Pine Road (8 m) which will be left under vegetation. Approvals will be obtained from the Forestry Division to clear and remove any remaining pine trees from the area that is to be worked. The remainder of the vegetative cover will then be removed using bulldozers. Ecoengineering 15 of 118 environmentally appropriate development for the Caribbean

12 BESTCRETE AGGREGATES LIMITED EIA FOR MINING OF SAND AND GRAVEL AT PINE POAD, MATURA Once the vegetation has been cleared, the top soil (0.5 m to 0.75 m) and overburden (5 m to 10 m) will be stripped away to expose the useable sand and gravel. Clearing and stripping will be done using a Kolbelco Excavator and New Holland Bulldozer or equivalent units. The top soil will be stored on a section of worked area for later site rehabilitation. Even though most rainfall onto this mine percolates into the sand, channels will be cut to effectively manage overland flow Winning of the Gravel Deposits The gravel deposits will be excavated using the Strip Mining Method which is the safest, most efficient and cost effective manner of winning the gravel and which is the dominant method of excavation practised by the majority of sand and gravel quarry operators. This method allows maximum extraction of the gravel and affords continuous rehabilitation of the land on a phased basis through backfilling. The steps involved are as follows: < Using the bulldozer and the excavator, vegetation and overburden over 2 acres on the eastern boundary will be cleared to the gravel layer and capped. The topsoil will be stored on a levelled section of the worked area for use in later rehabilitation. The overburden will be placed temporarily on a section of the 2 acre parcel and used in progressively restoration. < Gravel will be excavated in a north-south direction in strips 50 feet to 60 feet wide and 200 feet long. Any interbedded clay encountered will be stockpiled on the overburden area. The rate of excavation will be approximately 30,000 cu. yd. /month (1,500 cu. yd/ day). < Successive north-south strips will be excavated until the entire 2 acre parcel is mined. < Test pits will be excavated 17 feet to 20 feet below the previous excavation to evaluate the potential for deeper gravels. If deeper gravels are encountered excavation in this area will be carried out using dragline cranes. < Successive 2 acre parcels will be cleared and all shallow gravel will be extracted to exhaustion or to the limit of the available equipment. < Borehole testing will be conducted and if deeper gravels are encountered areas of commercial gravel and clay or non-commercial gravel will be identified. < If commercial gravel is identified, beginning at the eastern boundary and using the strip mining method, the second level of gravel will be excavated to the limits of the excavator. In the event that additional reserves are encountered at depth, a dragline will be used to recover the remaining reserves below the groundwater table. Ecoengineering 16 of 118 environmentally appropriate development for the Caribbean

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15 BESTCRETE AGGREGATES LIMITED EIA FOR MINING OF SAND AND GRAVEL AT PINE POAD, MATURA Exhausted areas will be progressively backfilled. Vegetation and overburden will be placed at the base and a 12 inches layer of top soil will be placed on the surface. < At the end of the quarrying all mined areas will be backfilled and levelled. On average, 20,000 metric tonnes to 30,000 metric tonnes of pitrun will be stockpiled on-site. 3.4 Transport and Processing Bestcrete is negotiating with Readymix (West Indies) Limited to process their pitrun at Readymix facility in Melajo, off Tapana Road. This facility is Source Registered and operates under Source Registration No. WWG 91 from the Environmental Management Authority (see Section B.4.5 of Appendix B). A letter indicating Readymix willingness to process pitrun material from the BAL Matura Quarry is included in Appendix D. The following sub-sections describe the transport of pitrun to the Readymix facility, Readymix processing plant, the water recovery system at Readymix, and the transport of processed sand and gravel to Bestcrete s Block Manufacturing Plant Transport of Pitrun Pitrun material excavated at the Bestcrete Matura Quarry will be transported to the Readymix (West Indies) Limited facility in Melajo, off Tapana Road for processing (see Figure 3-6). Pitrun will be excavated at an average rate of approximately 30,000 yd 3 per month, or approximately 1,500 yd 3 per day. This will be transported in a fleet of eight 20 yd 3 trucks. Therefore, there will be 75 truck trips per day transporting material from the quarry, and 75 trips per day of empty trucks returning to the quarry Processing Plant Readymix processing plant is described in more detail in Appendix D.II, and summarized hereunder. Processing of pitrun material at the Readymix facility is done using four types of equipment: < Primary Separator, < Hydrocyclones, < Vibrating Wash Screens, and < Crusher. These are shown in the Process Flow Block Diagram in Figure 3-7. Ecoengineering 17 of 118 environmentally appropriate development for the Caribbean

16 BESTCRETE AGGREGATES LIMITED EIA FOR MINING OF SAND AND GRAVEL AT PINE POAD, MATURA Primary Separator The primary separator consists of a dry vibrating screen onto which pitrun material is placed. This separates the pitrun into a coarse fraction and a fine fraction. The fine fraction consists of sand and silt, and this is directed to the hydrocyclones. The coarse fraction consists largely of gravel-sized particles with some sand and silt adhering, and this is directed to the vibrating wash screens Hydrocyclones The fine fraction from the Primary Separator is mixed with water and pumped up to one of two Hydrocyclone units, which discharge sand particles through one port, and mixed water and silt through another. Sand is transported to stockpiles by conveyor belts, while silty water flows into the water recovery system (see Section 3.4.3, below) Vibrating Wash Screens The coarse fraction from the Primary Separator is washed over Vibrating Wash Screens to remove adhering silt and sand, and to separate the gravel into different sizes. The 3/8-inch gravel is held in hoppers from which they are discharged to trucks. The ¾-inch gravel is moved via conveyor belts to stockpiles, and the oversize is moved by conveyor belt to the Crusher Crusher Gravel and cobbles larger than ¾-inch size are moved to the Crusher via conveyor belt, to be broken up into smaller pieces and returned to the intake of the Vibrating Wash Screen for processing Water Recovery Silty water from the Hydrocyclones and the Vibrating Wash Screen is recovered for re-use as wash water, using one of two processes: Clarifiers or Settling Ponds (see Process Flow Block Diagram in Figure 3-8). Ecoengineering 18 of 118 environmentally appropriate development for the Caribbean

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23 BESTCRETE AGGREGATES LIMITED EIA FOR MINING OF SAND AND GRAVEL AT PINE POAD, MATURA Clarifiers The Readymix facility includes three Jadair Water Settler / Clarifiers. Wastewater from one of the Hydrocyclones and from the Vibrating Wash Screen is pumped into a mixer tank where polymer is added. This mixture is then fed into in the main tank of the Settler / Clarifier, where the polymer enhances the formation of large flocs. The flocs (coalesced suspended solids) sink to the floor of the main tank, and clarified water overflows from the main tank and is piped back for reuse. A moving paddle system scrapes the settled flocs out of the tank, down a chute. They are piled up to allow continued de-watering, and then placed within the compound to fill in low areas Settling Ponds The alternative water recovery system is a series of settling ponds, the layout of which is shown in Figure 3-9. The topography of the land is used to allow flow by along most of the system. The water recovery system centers on a reservoir from which relatively silt-free water is pumped to the Hydrocyclones and the Vibrating Wash Screens. Outflow from the Clarifiers (see Section , above) also flows into this reservoir. From the Hydrocyclones and the Vibrating Wash Screens, silty water flows via a drain to the Primary Settling Pond where much of the silt settles out of the water. Water then flows from the Primary Settling Pond via a drain to the Secondary Settling Pond, where the settling of sediment continues. From the Secondary Settling Pond, water flows into the Tertiary Settling Pond via a pipe, and settling of sediment continues. Water is discharged from the Tertiary Settling Pond via a drain which discharges into the upper reaches of the reservoir. Over time the ponds will become silted up, and they are then dredged using an excavator. The settled silt which is removed from the ponds is placed within the compound to fill in low areas. Ecoengineering 19 of 118 environmentally appropriate development for the Caribbean

24 BESTCRETE AGGREGATES LIMITED EIA FOR MINING OF SAND AND GRAVEL AT PINE POAD, MATURA Transport of Product When pitrun material is processed, the product streams consists of sand and gravel suitable for use in construction works, and silt which is carried away in the wastewater. Processing of pitrun from the Matura Quarry is expected to yield 75 percent of useable product. Based on an intake of 1,500 yd 3 per working day, product is expected to be produced at a rate of 1,125 yd 3 per working day. This will be transported from the Readymix facility to Bestcrete s Block Manufacturing Plant on the Churchill Roosevelt Highway in Mausica (see Figure 3-10) in a fleet of twelve 20 yd 3 trucks. Therefore, there will be 57 truck trips per day transporting processed sand and gravel from the Readymix facility. 3.5 Rehabilitation Rehabilitation of the worked out areas will be progressive. That is, rehabilitation will be carried out at each completed portion of the quarry, rather than after the entire deposit has been excavated. A Rehabilitation Plan has been developed for the site and is presented in Appendix E. When the quarrying is completed it is expected that approximately 50% of the site will be under approximately 5 feet to 10 feet of water while the remainder will be dry. The preferred after-use for this site is forestry since this was the original land use. 3.6 Workforce and Equipment The workforce at the quarry will be as follows: < Quarry Supervisor, < 4 Heavy Equipment Operator, < 20 Truck Drivers, < 2 Quarry Checkers, and < 2 Security Officers. It is envisaged that the majority of the pitrun will be mined dry, given the depth of the water table (15 ft to 20 ft). The following equipment will therefore be utilized: < 2 D350 New Holland Bulldozers or equivalent, < 2 SK335 Kolbelco Excavators or equivalent, < 1 Water Truck, and < 8 Ten Wheeler Dump Trucks. Ecoengineering 20 of 118 environmentally appropriate development for the Caribbean

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29 BESTCRETE AGGREGATES LIMITED EIA FOR MINING OF SAND AND GRAVEL AT PINE POAD, MATURA 3.7 Ancillary Facilities Proposed ancillary facilities include: < 1 Site office; < 1 Diesel Storage Tank (1000 gallons); and < 3 Water Storage Tanks (1000 gallons, each). It should be noted that diesel fuel is the only hazardous substance used in this project. A digital copy of the Material Safety Data Sheet (MSDS) is provided in Appendix Z to this EIA Report. 3.8 Utilities Utilities will be provided to the proposed quarry as follows: < Water will be trucked to the site for drinking and wash down purposes, including wetting of the road. < Since this will be a daylight operation no electricity will be required from T&TEC; however a generator will be utilized where necessary. < All telecommunications will be by mobile phones. 3.9 Waste Management The types of waste that will be generated from the quarry include: < Solid waste, < Sewage, and < Domestic wastewater. Approximately 2 to 4 million cubic meters per annum of overburden will be generated. However neither overburden nor topsoil are considered waste materials and will be stored and reused on the site for rehabilitation of worked out areas. Effluent from settling ponds will be pumped to the Melajo River after sediment has settled. Used oils and lubricants will be disposed off-site. Ecoengineering 21 of 118 environmentally appropriate development for the Caribbean

30 BESTCRETE AGGREGATES LIMITED EIA FOR MINING OF SAND AND GRAVEL AT PINE POAD, MATURA Solid waste will be collected in large bins placed at strategic locations and removed to the Heights of Guanapo landfill for disposal. This will comprise: < Packaging material. < Old tyres. < Discarded containers, barrels, pieces of wood, old tools, hoses and miscellaneous items. < Domestic waste (soft drink cans, food containers, paper cups, wrapping material, etc). Chemical toilets will be utilized on the site when operations commence and 2 toilets and 2 urinals will be constructed with a septic tank and soakaway system in accordance with standards outlined by the Water and Sewerage Authority (WASA). Used oils and lubricants as well as chemicals will be stored in barrels and collected by the Solid Waste Management Company for recycling. The mining will be conducted in such a way to create a system of retention ponds for all stormwater discharge. Water will only be discharged to the river after sediment has settled Project Schedule Mining of pitrun will continue until recoverable reserves have been excavated. Given the size of the reserve it is estimated that the quarry will continue to operate for approximately 5 years. Clearing and grubbing of the area will commence 2 weeks after the awarding of a mining license starting from Tractor Road and proceeding westward using a bulldozer, excavator and trucks. Approximately 5 acres will be cleared at a time. The phased rehabilitation will commence in the dry season and will continue throughout the project; but rehabilitation efforts will be concentrated in the dry season. Ecoengineering 22 of 118 environmentally appropriate development for the Caribbean