Evaluasi Kolam Pengendapan (Settling Pond) Limbah Beton Ready-Mix pada Batching Plant

Abstract

Air cucian dari batching plant dan mixer truck menghasilkan limbah cair beton sebanyak 7,5 m3 yang mengandung sedimen rata-rata sebesar 1,5 m3/hari. Limbah tersebut dialirkan dan diendapkan pada kolam pengendapan (settling pond). Kolam pengendapan (settling pond) untuk limbah beton ready-mix pada site Sedayu belum berfungsi secara maksimal karena limbah tidak terendap sempurna dan mengalir langsung ke sungai serta frekuensi pengerukan kolam sampai 8 kali dalam satu bulan. Penelitian bertujuan untuk menganalisis kapasitas kolam pengendapan yang sesuai serta frekuensi pengerukan kolam. Tahapan penelitian meliputi analisis curah hujan rencana dengan metode Gumbel, debit limpasan, dan waktu pengerukan. Curah hujan rencana untuk periode ulang hujan 2 tahun diperoleh sebesar 103,88 mm dan rata-rata intensitas hujan 9,4 mm/jam. Berdasarkan hasil analisis diketahui bahwa kapasitas kolam yang ada sebesar 67,2 m3, lebih kecil daripada standar kapasitas minimal yang berlaku. Site Sedayu membutuhkan kolam pengendapan berkapasitas 75,74 m3, dengan panjang 14 m, lebar 4 m, dan kedalaman 1,4 m. Kolam pengendapan direkomendasikan untuk dikeruk secara berkala, setiap 25 hari.

Waste water from the batching plant and mixer truck produced concrete liquid waste 7.5 m3/day which contained sediment of 1.5 m3/day. The waste was flowed and deposited in the settling pond. The settling pond for ready-mix concrete waste at the Sedayu site has not functioned optimally because the waste was not completely settled and flowed directly into the river and the frequency of dredging is up to 8 times/month. The research aimed to analyse the capacity of a suitable settling pond and the frequency of pond dredging. The stages of the research included planned rainfall analysis using the Gumbel method, runoff discharge, and dredging time analysis. The planned rainfall for the 2 years rainfall returned period was 103.88 mm and the average rainfall intensity was 9.4 mm/hour. The analysis result showed that the existing settling pond capacity was 67.2 m3. This capacity is smaller than the standard of settling pond minimum capacity. The Sedayu site needed a settling pond with a capacity of 75.74 m3, with 14 m in length, 4 m in width, and 1.4 m in depth. The settling ponds is recommended to dredge periodically, every 25 days.