WIJAYA, BAGUS ARIEF (2015) STUDI HIDROGEOLOGI PADA RENCANA PENAMBANGAN BATUBARA DI DAERAH MUARA BAKAH, IUP PT. DUTA NURCAHYA, BARITO UTARA,PROVINSI KALIMANTAN TENGAH. Other thesis, UPN "Veteran" Yogyakarta.
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Abstract
Berkaitan dengan rencana PT. Duta Nurcahya untuk membuat bukaan tambang yang baru sehingga studi hidrogeologi sangat diperlukan. Hal ini dikarenakan lokasi rancangan bukaan tambang yang berdekatan dengan sungai
besar di Kalimantan Tengah yaitu Sungai Lahai. Lokasi Sungai Lahai yang sangat dekat dengan lokasi rancangan bukaan tambang berpotensi mempengaruhi kondisi
airtanah disekitar bukaan tambang. Data curah hujan dari Stasiun Meteorologi Muara Teweh selama 14 tahun
(2000-2013) diketahui bahwa curah hujan rata-rata tahunan di daerah penelitian sebesar 3146 mm/tahun, sedangkan hari hujan rata-rata sebesar 189 hari/tahun.
Curah hujan di daerah penelitian tergolong sangat tinggi (hujan sangat lebat), hal ini ditunjukan oleh nilai intensitas curah hujan lebih besar dari 20 mm/jam yaitu
antara 20,12 mm/jam hingga 26,30 mm/jam.
PT. Duta Nurcahya berada pada formasi Warukin. Formasi Warukin tersusun dari batupasir kuarsa berbutir halus, kurang padat dan mengandung sisipan batulempung karbonan dan batulanau karbonan berlapis tebal. Batupasir
yang bertindak sebagai akuifer perlu diketahui karakterikstik dan pengaruhnya terhadap rancangan bukaan tambang. Berdasarkan hasil studi hidrogeologi yang telah dilakukan, diketahui terdapat dua jenis akuifer, yaitu akifer bebas dan akuifer tertekan. Akuifer bebas
terdiri dari batupasir halus. Sedangkan akuifer tertekan terdiri dari batupasir dengan ukuran pasir halus yang terperangkap lapisan batulempung. Sebaran
ketebalan akuifer bebas dan akuifer tertekan di daerah penelitian tidak merata. Akuifer bebas memiliki ketebalan antara 3,00 – 22,60 meter, akuifer tertekan
memiliki ketebalan antara 8,00 – 37,35 meter. Lapisan akuifer secara umum memilik kemiringan dari Barat Daya ke Timur Laut. Hasil pengujian berdasarkan metode slug test diketahui nilai permeabilitas (k) akuifer berkisar antara (1,1294 . 10 v -6 – 5,3528 . 10-6) meter/detik. Sedangkan
melalui uji pumping test pada lubang bor GH_DN_05 didapatkan nilai konduktivitas hidrolik (K) sebesar 1,330 . 10-5 meter/detik. Dilihat dari jenis batuan penyusun akuifer, nilai permeabilitas, dan konduktivitas hidrolik yang kecil maka potensi airtanah di daerah penelitian relatif rendah sehingga pengaruh penambangan batubara terhadap keberadaan airtanah (terutama airtanah bebas)
tidak signifikan. Pada kondisi nilai permeabilitas yang tergolong rendah, aliran airtanah di dalam akuifer relatif terbatas (temporary), terlebih lagi hanya
dipengaruhi oleh perbedaan muka airtanah akibat penggalian dan gaya gravitasi. Berdasarkan hasil analisis kimia terhadap conto air menunjukan bahwa air
di daerah penelitian merupakan air kelas satu (I) dan kelas tiga (III).
Related with PT. Duta Nurcahya’s plan to make the new mine openning so hydrogeological study is needed. It was caused by the location of mine openning
is near to large river in Central Borneo namely Lahai river. Lahai river’s location is very close with mine opennings so it potentially affect groundwater condition
around mine openning. Rainfall data from Muara Teweh Station Meteorology during 14 years
(2000-2013) shows that years rainfall average at research area is 3146 mm/year, meanwhile days rainfall average is 189 days/year. Rainfall in research area is very
high (very heavy rain), it is shown by rainfall intensity value is bigger than 20 mm/hour that is about 20,12 mm/hour till 26,30 mm/hour. PT. Duta Nurcahya is located above Warukin formation. Warukin formation
is composed by quartz sandstone with fine grained, less dense, and inserted carbon mudstone and carbon siltstone. Sandstone which act as aquifer must be
knowed the characteristic and effect to mine opennings.
Based on hydrogeological study has been done, there are two kinds of aquifer that are unconfined aquifer and confined aquifer. Unconfined aquifer is
composed by fine grained sandstone. Meanwhile confined aquifer composed by fine grained sandstone which trapped by mudstone. Distribution of unconfined
and confined aquifer in research area is not spread. Confined aquifer thickness is
about 3,00 – 22,60 meters, unconfined aquifer thickness is about 8,00 – 37,35 meters. Generally the declivity of aquifer layers from South West to North East.
Based on slug test methode the result of aquifer permeability value is about(4,600 . 10-6 – 7,3060 . 10
-7) meter/second. Meanwhile by pumping test methode
the result of hydraulic conducticity values is 1,330 . 10
-5 meter/second. Looked from aquifer stone composer, permeability values, and hydraulic conductivity
value can be concluded that groundwater potenstial in research area is relatively low. The effect of coal mining to the presence of groundwater (especially
unconfined groundwater is not significant. In the condition of permeability value is relatively low, the flow of groundwater in the aquifer is relatively limited, more
that just influenced by differences in groundwater level as a result ofexcavation
and gravity. Based on chemical laboratory analysis’ result shows that water sample at
research area is classified in fisrt (I) class and third (III) class.
| Item Type: | Thesis (Other) |
|---|---|
| Subjects: | T Technology > TA Engineering (General). Civil engineering (General) |
| Divisions: | Faculty of Engineering, Science and Mathematics > School of Engineering Sciences |
| Depositing User: | Eko Yuli |
| Date Deposited: | 12 May 2016 01:47 |
| Last Modified: | 13 Oct 2022 04:19 |
| URI: | http://eprints.upnyk.ac.id/id/eprint/702 |
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