Seite - 284 - in Book of Full Papers - Symposium Hydro Engineering

Table 4 Dredging in Wlingi Dam Year Dredging with Spoil Bank Disposal (m3) Dredging with Riverine Disposal to Channel Below (m3) 2013 150,800 100,031 2014 283,148 110,140 2015 377,384 2016 100,436 250,475 2017 115,020 Source: Perum Jasa Tirta I 5. FINANCIAL ANALYSIS OF SEDIMENT MANAGEMENT 5.1 CALCULATION OF FLUSHING AND DREDGING COST As a basic for evaluation of financial aspects assumed as follows:  Flushing costs include flushing operational costs, lost potential revenue costs from water services and the cost of losses of electricity production due to discontinued hydropower operations.  The amount of sediment due to flushing is calculated based on the average of flushing data for 5 years (2009 to 2013, since 2014 and 2015 have no flushing, whereas 2016 and 2017 volumes of sediments are flushed greatly considering 2 years previously not flushing)  Loss of hydropower production is assumed based on the operating hour loss multiplied by the installed capacity multiplied by 75% (34,000,000 x 38 x 0.75 = 969,000 kWh)  Dredging unit price refers to the existing unit price estimate in Wlingi Reservoir, which is Rp 64.100 / m3. Analysis of unit price as attached  Tariff of water service for hydropower based on tariff which is valid in 2017 at Jasa Tirta I Public Corporation, which is Rp 167 / kWh  Value of electricity benefit is calculated based on the basic electricity tariff issued by National Electricity Company in 2017 is Rp 1.352 / kWh  Flushing is assumed not influence to irrigation because the flushing implementation is less than 2 days (38 hours) and not carried out during the dry season.  During flushing there is no loss due to the temporary interruption of irrigation water supply, domestic and industrial raw water due to the relatively short implementation period.  Operational cost of flushing based on the existing data in Jasa Tirta Public Corporation is Rp 133.330.000, 284