Analisis Manajemen Risiko pada Pekerjaan Underwater Dalam Penutupan Inlet Bottom-Outlet di Bendungan Cirata

Faris Al Rasyid, Prof. Dr. Techn. Ir. Danang Parikesit, M.Sc. (Eng)., IPU., APEC.Eng., QRGP

2026 | Tesis | S2 Teknik Sipil

Bendungan Cirata merupakan infrastruktur strategis Pembangkit Listrik Tenaga Air (PLTA) yang memegang peran vital dalam sistem kelistrikan Jawa–Madura–Bali (JAMALI), termasuk fungsi black start dan pengendali frekuensi. Namun, salah satu bangunan pelengkapnya, yaitu saluran bottom outlet , mengalami kebocoran sejak tahun 2021 yang diduga berasal dari kegagalan High Pressure Gate (HPG). Perbaikan menyeluruh mensyaratkan penutupan inlet bottom menggunakan hemispherical bulkhead yang harus diturunkan di bawah air pada kedalaman 45–60 meter. Pekerjaan ini memiliki risiko tinggi terhadap personel, sistem, maupun lingkungan kerja, terutama karena struktur telah terendam lebih dari 35 tahun, kondisi trashrack tidak pasti, serta crane barge jarang dioperasikan dan kurang terawat.
Penelitian ini bertujuan untuk mengidentifikasi, menganalisis, dan memprioritaskan risiko dalam proses penurunan hemispherical bulkhead menggunakan kombinasi metode HAZOP (Hazard and Operability Study) dan FMEA (Failure Mode and Effect Analysis). HAZOP digunakan untuk mengidentifikasi deviasi dari kondisi operasi normal secara sistematis dengan pendekatan guide words pada sepuluh node operasional, sedangkan FMEA digunakan untuk mengevaluasi tingkat keparahan (Severity), kemungkinan terjadinya (Occurrence), dan kemampuan deteksi (Detection) untuk menghasilkan Risk Priority Number (RPN) sebagai dasar prioritas risiko. Data primer diperoleh melalui pemeriksaan bawah air menggunakan penyelam, ROV, side scan sonar, pengukuran batimetri, laser scanner, serta Focus Group Discussion yang melibatkan para ahli bendungan dan pemangku kepentingan terkait. 
Hasil penelitian menunjukkan bahwa pengembangan SOP penutupan menghasilkan 10 aktivitas dengan 15 risiko teridentifikasi dan 38 ancaman (penyebab), yang dianalisis menjadi 38 skenario deviasi pada HAZOP. Integrasi dengan FMEA menghasilkan 8 failure modes level High (RPN 64–80), 13 Moderate to High, 14 Moderate, dan 3 Low to Moderate. Risiko paling kritis meliputi kecelakaan penyelaman pada kedalaman lebih dari 50 meter (decompression sickness, narkosis, oxygen toxicity), tertutupnya kembali pintu trashrack saat pengangkatan guide wire eksisting, ketidaksepakatan pola operasi tiga waduk kaskade, serta kegagalan pengoperasian trashrack. Berdasarkan hasil prioritisasi tersebut, dirumuskan empat alternatif penutupan, dan Alternatif 4 yaitu implementasi bertahap dengan memitigasi risiko Prioritas 1 dan 2 (34 task) sebelum perencanaan penurunan, dilanjutkan dengan risiko Prioritas 3 dan 4 (28 task) pada tahap persiapan, direkomendasikan sebagai pilihan paling seimbang antara penurunan risiko dan keterlaksanaan operasional. Penelitian ini memberikan kontribusi akademik berupa integrasi metodologi analisis risiko HAZOP–FMEA yang jarang diterapkan pada pekerjaan bawah air untuk bendungan di Indonesia, serta panduan praktis bagi operator PLTA dalam melaksanakan pemeliharaan infrastruktur kritis secara aman dan berkelanjutan.

Cirata Dam is a strategic hydroelectric power plant (HEPP) that plays a vital role in the Java–Madura–Bali (JAMALI) electricity system, including black-start and frequency-control functions. However, one of its appurtenant structures, the bottom outlet, has experienced leakage since 2021, presumably due to a failure of the High Pressure Gate (HPG). A comprehensive repair requires closing the Inlet bottom with a hemispherical bulkhead, which must be lowered underwater to a depth of 45–60 meters. This operation poses High risks to personnel, systems, and the working environment, particularly because the structure has been submerged for more than 35 years, the trashrack condition was uncertain, and the crane barge had rarely been operated and maintained.
This study aims to identify, analyze, and prioritize the risks associated with the hemispherical bulkhead lowering process using a combination of the Hazard and Operability Study (HAZOP) and Failure Modes and Effects Analysis (FMEA) methods. HAZOP was applied to systematically identify deviations from normal operating conditions using guide words on ten operational nodes, while FMEA was used to evaluate Severity, Occurrence, and Detection to generate the Risk Priority Number (RPN) as the basis for risk prioritization. Primary data were obtained through underwater inspections using divers, ROVs, side-scan sonar, bathymetric surveys, and a laser scanner, as well as Focus Group Discussions involving dam experts and relevant stakeholders.
The results show that the development of the standard operating procedure yielded 10 activities, 15 identified risks, and 38 threats (causes), which were analyzed into 38 deviation scenarios in HAZOP. The integration with FMEA resulted in 8 High-level failure modes (RPN 64–80), 13 moderate-to-High, 14 moderate, and 3 low-to-moderate. The most critical risks include diving accidents at depths exceeding 50 meters (decompression sickness, narcosis, oxygen toxicity), the trashrack gate reclosing during the removal of the existing guide wire, disagreement over the operating pattern of the three cascade reservoirs, and failure of trashrack operation. Based on the prioritization, four closure alternatives were formulated, and Alternative 4, a staged implementation that mitigates Priority 1 and 2 risks (34 tasks) before the lowering plan, followed by Priority 3 and 4 risks (28 tasks) during the preparation stage, is recommended as the most balanced option between risk reduction and operational feasibility. This research makes an academic contribution by presenting an integrated HAZOP–FMEA risk analysis methodology that is rarely applied to underwater dam works in Indonesia, as well as practical guidance for HEPP operators on maintaining critical infrastructure safely and sustainably.

Kata Kunci : Analisis Risiko, Cirata, Bottom outlet, Inlet bottom-outlet, HAZOP, FMEA