Abstrak. TPA Ngipik Kabupaten Gresik dalam perencanaannya dibuat dengan menerapkan sistem Sanitary Landfill. Namun saat ini TPA Ngipik telah beroperasi dengan sistem pengelolaan Open Dumping sejak tahun 2003. Penerapan sistem Open Dumping menyebabkan pencemaran mudah terjadi baik pencemaran air, tanah dan udara. Penelitian ini mengorelasikan data resistivitas 2D, uji resistivitas skala laboratorium dan data hasil pemboran. Penelitian ini ditujukan untuk mengidentifikasi sebaran lindi dan kedalamannya berdasarkan korelasi data tersebut. Telah dilakukan pengukuran Resistivitas 2D Konfigurasi Wenner-Schlumberger dengan spasi 0.5 m dan total panjang 15.5 m pada musim kemarau dan musim penghujan. Dilakukan pula pengujian resistivitas skala laboratorium sebagai data korelasi Resistivitas 2D. Hasil penelitian menunjukkan bahwa hasil inversi pengukuran sesuai dengan litologi lempung dengan rentang resistivitas sebesar 0.1 -43.78 Ωm dan telah sesuai dengan data hasil pemboran berupa litologi lempung hingga kedalaman 30 m. Pada lintasan pengukuran juga telah teridentifikasi terdapat sebaran air lindi dengan nilai resistivitas sebesar 0.1 -1.5 Ωm. Kedalaman sebaran air lindi dari hasil penelitian ialah lebih besar dari 1 meter. Kata Kunci : TPA Ngipik, sebaran, air lindi, resistivitas Abstract. Ngipik Landfill at Gresik Regency in the planning will be made with applied sanitary landfill system. But, since 2003 Ngipik Landfill have been operated with Open Dumping System. Applied of Open Dumping System cause a pollution occurred easily, both pollution of water, soil and air. This research correlate 2D Resistivity Data, laboratory scale resistivity test and boring data. The purpose of this research is to identify a leachate migration based on correlation of primer and secondary data. Geoelectrical measurement with wenner-schlumberger array have been done with 0.5 meters space of electrode and 15.5 meters length of line during dry season and wet season. Laboratory scale resistivity test have also been performed as correlation data to 2D Resistivity. The results showed that resistivity inversion appropriate with clay that resistivity value is 0.1 -43.78 Ωm and appropriate with boring data that show clay lithology until 30 meters depth. At measurement line have been identified a leachate migration with resistivity value 0.1 -1.5 Ωm. The depth of leachate migration from this research is more than 1 meters.

D89Abstrak-TPA Ngipik Kabupaten Gresik berdiri dengan sistem Open Dumping selama 14 tahun yang menyebabkan terjadinya pencemaran air tanah oleh air lindi. Untuk mendapatkan kontras yang jelas pada nilai resistivitas yang diduga sebagai sebaran air lindi, dilakukan pengujian resistivitas skala laboratorium. Pengujian ini ditujukan untuk mengetahui pengaruh fluida pada sampel tanah TPA Ngipik. Sampel tanah yang diuji yakni dua sampel dengan dibedakan fluida yang tersaturasi. Digunakan resistivitas dengan konfigurasi Wenner dengan jarak antar elektroda sebesar 1 cm. Didapatkan hasil bahwa sampel A mengalami kejenuhan dan nilai resistivitas yang stabil pada penambahan aquades tetes ke-80. Sedangkan pada sampel B mengalami kejenuhan dan nilai resistivitas yang stabil pada penambahan air lindi tetes ke-40. Nilai resistivitas sampel B dengan kandungan air lindi lebih kecil daripada sampel A dengan kandungan air aquades. Sampel tanah lempung dengan kandungan air lindi lebih konduktif dibandingkan dengan kandungan air aquades.

Using natural soil in landfill sites for landfill construction is common in developing countries such as Indonesia. However, the risk of contaminated soil being used as material needs to be reduced by soil improvement to meet the landfill base requirement. Geopolymer is one stabilization material with high durability towards the contaminants, in which fly ash is one of the best geopolymer raw materials due to its readily great supplies and noble properties. The present study investigates fly ash-based geopolymer (FAG) influence on the treated-contaminated soil properties specifically for landfill liner purposes. The studied soils were collected from Ngipik Landfill, an indiscriminate municipal landfill in Gresik, East Java-Indonesia. The samples were obtained from three different locations around the waste mound and stabilized with FAG at 5, 10, and 15 wt.% of unstabilized soil at its optimum water content compared to the natural soil. The laboratory-scale tests were conducted, including the unconfined compressive strength test, standard compaction proctor, consolidation test, and the permeability test to understand the treated-soil characteristics better. The Scanning Electron Microscope (SEM) analysis was gathered to examine the treated soil's micro-properties. The results denoted that the FAG addition increases the soil's compressive strength up to 36% and reduces the compressibility to up to 60%. The permeability shows a slight decrement in 5% and 10% of FAG addition. The SEM image indicates that the FAG made bonds and fills the void. This study concludes the FAG enhances the mechanical properties of Ngipik Landfill soil despite the contamination.

Abstrak. Tempat Pembuangan Akhir (TPA) Ngipik menggunakan sistem Openg Dumping, sehingga dengan sistem ini akan menyebabkan pencemaran lingkungan salah satunya melalui air lindi yang dihasilkan dari sampah. Telah dilakukan penelitian untuk mengidentifikasi air lindi menggunakan metode Inversi VLF-EM. Dari hasil pengolahan data VLF menggunakan inversi diperoleh nilai resistivitas daerah yang teridentifikasi adanya air lindi berkisar 1.6-2.5 yang sudah tersebar hingga kedalaman 15 m. Hal ini mengidentifikasikan bahwa air lindi sudah tersebar di Area TPA Ngipik. Kata Kunci : Air Lindi, Resistivitas, TPA Ngipik, , VLF-EM Abstract. Ngipik landfill uses Open Dumping system, so with this system will cause environmental pollution, one of them through leachate water generated from waste. Research has been conducted to identify leachate water using VLF-EM Inversion method. From VLF data processing results using inversion and laboratory measurement obtained resistivity value of area which the existence of leachate water is identified ranged from 1.6-2.5 Ωm which have spread to 15 m depth. This indicates that leachate water is already scattered in Ngipik landfill.

Abstract. This paper presents an investigation based on affected areas of earthquakes based on the micro-tremor horizontal-to-vertical ratio (HVSR) method around the Ngipik Landfill, Gresik. Ngipik landfill applies an Open dumping system with no protective layer to prevent groundwater pollution. Hence, the effect of the earthquake was investigated for preliminary assessment of leachate's leakage. The micro-tremor measurements were performed by dividing the area into a grid with a 25m distance. The predominant frequency (f0) ranges between 1.1 and 3.65 Hz and the peak of HVSR (Am) varies from 2.04 to 7.16. The vulnerability index (kg) displayed the level of soil damage due to ground motions; the highest kg values signified the weaker zones during earthquakes and also indicated the leachate spread. The result of this paper might consider to seismic stability analysis of leachate recirculation landfill.