Posted 26 June 2001  [RCT]

 

Submarine Tailings Disposal (STD) of Newmont Minahasa Raya

(PT. NMR) at Buyat Bay, North Sulawesi, Indonesia:

 The Impacts on Seabed Contour and Fishing Ground

 

 

Veronica A. Kumurur^1* & Markus T. Lasut^2*

E-mails: vkumurur@yahoo.com  and  mlasut@hotmail.com

 

 

¹ Architecture Dept., Faculty of Engineering, Sam Ratulangi University, Manado, Indonesia

² Toxicology & Marine Pharmaceutics, Faculty of Fisheries and Marine Science,

Sam Ratulangi University, Manado, Indonesia

^* Center for Environmental Studies and Natural Resources (CESNR/PPLH-SDA),

Research Institution, Sam Ratulangi University, Manado, Indonesia

 

 

Summary

 

This review highlights significant impacts of STD system applied by PT. NMR in Buyat Bay. The application of the system causes negative impacts on the marine ecosystem and life quality of traditional fisherman. The impacts include change on seabed contour, change on marine productive areas, decreasing the number of fish species that used to be caught, and change on fishing ground for traditional fisherman. The negative impact on economic aspect include decreasing the family income from fishing activity, increasing the risk to fishing, and extra cost for health insurance.

 

 

Introduction

 

In Indonesia, STD (submarine tailings disposal) system has been firstly applied in 1996 by a gold mining company, Newmont Minahasa Raya (PT. NMR), North Sulawesi, to discharge their tailings. The system has some pre-requirements that have to be approved, i.e. 1) the tailings must be deposited at deep water seabed; 2) the tailings must be deposited in low productive areas; 3) the tailings will not alter fishery (mari-culture, sanctuary, and fishing ground); 4) No toxic and heavy metals substances from the tailings that will be bio-accumulated to human food chain; and 5) the tailings will not alter other marine activities (example: tourism, beach recreation, and shrimp farming) (Kuntjoro, 1999).

             PT. NMR has chosen the STD system by using on-land tailings slurry line, in which outfall (the end of tailings pipeline) placed at ± 82m depth and ±900m horizontally distance from upper intertidal area or beach line at Buyat Bay, North Sulawesi Province, Indonesia (Anonymous 1994). Some impacts occur due to the system directly or indirectly, such as alter seabed contour of Buyat Bay, covering a large productive seabed area, change fishing ground, and affect economic aspect of traditional fisherman. These impacts have been reviewed and highlighted in this paper.

 

 

The Impact of STD of PT. NMR

 

1. The Impact on Seabed Contour

          Since 1996, PT. NMR discharges the tailings of slurry (liquid and solid forms) to Buyat Bay at ±82m depth (Anonymous 1994). In period of October 1 to December 31, 1998, amount of tailings discharged to the bay approximately 349,000 m³ (192,000 tons of solid) (Anonymous 1998). The amount of tailings discharged to the bay is ±2,000 per day. Change in seabed contour is a significant impact due to this activity. The impact can be seen on the bathymetric map comparison between the map published in 1995 (Figure 1) by Bakorsurtanal, Indonesia, (“Peta Lingkungan Pantai Tahun 1995") and the map published in 1997 by PT. NMR (Fig. 2).

 

 

 

 

 

 

Figure 1. The Bathymetric Map of Buyat Bay. Modified from “Peta Lingkungan Pantai Tahun 1995” published by Bakosurtanal, Indonesia. (Original map scale of 1:15,000)

 

 

 

 

Figure 2. The Bathymetric Map of Buyat Bay. Modified from bathymetric map published in 1997 by PT. Newmont Minahasa Raya (NMR).

 

 

 

             Figure 2 shows that approximated geographical coordinate of the tailings outfall is located at ±82m depth while at 30-50m depth shows in Figure 1. It clearly shows a difference between both maps. Assuming that we believe the map published by Bakorsurtanal, Indonesia, (of course we are), what happened at the time? Do PT. NMR used bathymetric map published in 1995 by Bakorsurtanal, Indonesia, when they want to locate the tailings site at Buyat Bay or they used their own bathymetric map as same as the map published in 1997? Clearly, at the same geographical coordinates (between both maps), the measured depth is different. Why? No body knows whether PT. NMR made a little manipulation in data to show deeper area to fulfill the pre-requirement for their STD or something else (assumed that at deep water can be found a thermocline). A deep marine water is a pre-requirement to set up STD (Ellis et. al. 1995). Figure 3 shows a bathymetric map made in 1999 by Research Team of Center for Environmental Studies and Natural Resources (CESNR/PPLH-SDA), Research Institution, Sam Ratulangi University (Anonymous 1999).

          An analysis has been carried out on Figure 2 & 3 and the result shows that the seabed area (in width) of Buyat Bay at 0-10m, 10-20m, 40-50m, and 50-60m are 100m square; at 20-30m, 30-40m, 50-60m, 60-70m, and 70-80m are 200-350m square; at 80-90m is 150m square. While in Figure 3, at 0-10m, 10-20m, 20-30m, 30-40m, and 40-50m are ±100m square; at 50-60m, 60-70m, and 70-80m area ±550-750m square; at 70-80m (at the end of tailings pipeline) is 550-750m square.

 

 

 

 

 

Figure 3. The Bathymetric Map of Buyat Bay. Modified from bathymetric map published in 1999 by Research Team of Center for Environmental Studies and Natural Resources (CESNR/PPLH-SDA), Research Institution, Sam Ratulangi University (Anonymous 1999).

 

 

             Figure 4 shows a cross-section (parallel with the tailing pipeline) has been made to compare seabed contour between the bathymetric map published in 1997 by PT. NMR and the map made by Research Team of CESNR (PPLH-SDA Unsrat) measured in 1999. There is a change in slope from the beach line to the tailing outfall. It was 5^o (8,9%) to 2,2^o (3,8%). From the result can be concluded that the Buyat Bay is not suitable (unfit) to set up STD system. The slope needed to set up a STD system for marine and coastal mining is 10-20^o (Kuntjoro, 1999).

 

 

 

 

 

Figure  4. A cross-section map (A-A) of tailing pipeline of PT. NMR at Buyat Bay.

 

 

2. The Impact on Fishing Ground

          Covering marine productive areas on seabed of Buyat Bay can alter marine ecosystem and make it unstable. Besides the tailings form a mount-like shape of sediment on seabed, they are distributed in area of 18-20m depth and 1 km in distance from the tailings outfall (Anonymous 1998). The covered area is marine productive areas for fishes, in which fisherman can catch fishes. The impact of this condition is decreasing in fish species used to be caught by the fisherman.

          Before PT. NMR dispose their tailings to the bay, number of fish species used to be caught by the Buyat Fisherman is 59 species. After 1997, it reduces to 13 species. The reduction is approximately 22.03%. Further impact is the fishing ground for traditional fisherman that used to be 75m become 1,200m to 4,500m from the beach line (Anonymous 2000). Consequently, the safety of the traditional fisherman to fish is higher.

 

 

 

Figure 5. Fishing ground of traditional Fisherman at Buyat Bay. The sketch made based on data collected on June 2000 (Anonymous 2000).

 

 

3. The Impact on Economic Aspect

 

          The change on the fishing ground at Buyat Bay due to tailings disposal affects economic aspect of entire traditional fisherman at Buyat Pante Village (approximately 53 families). Most of the fisherman got income from fishing activity. Before 1996, the average incomes of those families were Rp. 500,000 – Rp. 750,000 per family per month. After 1996 (after STD operated), the average incomes decrease up to Rp. 100,000 per family per month. Apparently, directly or indirectly, the change of fishing ground and unstable ecosystem are due to the tailings. Moreover, the tailings are consisted toxic and danger wastes (limbah B3) that can be accumulated to the fish and other biota as food sources of the fisherman and other coastal communities (Lasut & Veronica 2001). It needs extra cost for health check up.

          Concerning the change of fishing ground, the traditional fisherman must spend extra effort to fishing offshore, approximately 1,2 to 4,5 km. It causes more risk (unsafe) and more operational cost for them. As the result, the condition, directly or indirectly, can cause decreasing in life quality (Fig. 6).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 6. Scheme of relationship between life quality of Buyat Community and Submarine Tailings Disposal (STD) at Buyat Bay

 

 

 

References

 

 

 

Anonymous. 1994. Studi analisis dampak lingkungan kegiatan pertambangan emas di Minahasa dan Bolaang Mongondow,  Sulawesi Utara, Indonesia. Laporan Akhir, Laporan Utama. PT. Newmont Minahasa Raya, Jakarta.

 

Anonymous. 1998. RKL/RPL Report: Period October 1-December 31, 1998. PT. Newmont Minahasa Raya.

Anonymous. 1999. Kajian Kelayakan Pembuanagn Limbah tailing Ke laut di Perairan Teluk Buyat Sulawesi Utara. Laporan Akhir, Pusat Penelitian Lingkungan Hidup & Sumberdaya Alam (PPLH-SA UNSRAT) Universitas Sam Ratulangi bekerjasatna dengan Badan Pengendalian Dampak Lingkungan Kantor Menteri Negara Lingkungan Hidup, Indonesia (BAPEDAL-KLH).

Anonymous, 2000. Laporan Kegiatan Pemetaan Partisipatif masyarakat Pantai Buyat. Walhi Sulawesi Utara, Manado.

Anonymous. 2001. Kontaminasi Arsen (Ar) dan Merkuri (Hg) pada Masyarakat Buyat. Laporan Penelitian. Dalam Minamata ke Minahasa: Pencemaran Lingkungan di Teluk Buyat Akibat Aktifitas Pertambangan PT. Newmont Minahasa Raya. Walhi Sulawesi Utara, Manado.

Ellis, D.V., G.W. Poling & R.L. Baer. 1995. Submarine tailings disposal (STD) for mines: an introduction. Marine Georesources and Geotechnology 13: 3-18.

Kuntjoro, D. 1999. Sistem penempatan tailing di dasar laut. Page 11-21 in A.R. Ginting (ed.). Proceeding: submarine tailing placement (STP). Kawil Dep. Pertambangan & Energy, Prop. Sulawesi Utara bekerjasama dengan Fak. Perikanan & Ilmu Kelautan Unsrat, Manado.

M.T Lasut & V.A Kumurur, 2001. Penurunan Kualitas Lingkungan Perairan Teluk Buyat Akibat Aktifitas Tambang PT. Newmont Minahasa Raya: Tinjauan Singkat. Dalam Minamata ke Minahasa: Pencemaran Lingkungan di Teluk Buyat Akibat Aktifitas Pertambangan PT. Newmont Minahasa Raya. Walhi Sulawesi Utara, Manado.

M.T Lasut & V.A Kumurur, 2001. Pollution in Marine Coastal Environment: A Consideration for Designing Sustainable Development of Marine Resources. Ekoton 1(1): 22-28.

V.A Kumurur. 2001. Tentang Posisi Pipa Buangan Menurut Peta Bakosurtanal: Kajian Lepas. Dalam Minamata ke Minahasa: Pencemaran Lingkungan di Teluk Buyat Akibat Aktifitas Pertambangan PT. Newmont Minahasa Raya, Walhi Sulawesi Utara, Manado.