Environmental Assessment Using Integrated Risk Based Approach (IRBA) at Cahaya Kencana Landfill Site

—Cahaya Kencana landfill site located above the land belonging to the local government of Banjar District with land area 35,5 Ha, where used for Cahaya Kencana landfill 16,5 Ha, Kehati park 7,5 Ha, the remaining unused land is 11,5 Ha. Cahaya Kencana landfill site has been implementing the sanitary landfill system since 2014 with the existing area of 8.089,73 m 2 and the calculation results shows that sanitary landfill area can only use until the year 2021. So the goal that is to be achieved from this research is to evaluate the technical aspects and environment of Cahaya Kencana site with decision making tools. One of them through the assessment of environmental risk index or Integrated Risk Based Approach (IRBA). Risk Index (RI) assessment results using IRBA obtained 524,007 value with a category of moderate hazard evaluation, so that Cahaya Kencana site can be forwarded and rehabilitated into controlled landfill gradually. The strategy that needs to be done in the framework of Cahaya Kencana site is modifications of leachate treatment unit design.


I. INTRODUCTION
HE population growth in Banjar District is very rapid and increased especially in the capital of the district, Martapura subdistrict. This condition is also directly proportional to the increase in urban waste production. The increase in waste production led to increased area disposal. Cahaya Kencana landfill has been implementing the sanitary landfill system since 2014 until now with a condition that is almost full. Volume of garbage entered from the year 2014 to 2018 which is transported to the landfill reaches 376.621 m 3 or an average of 206,37 m 3 /day. Surely the problem requires environmental management as soon as possible, one of them by doing a risk assessment. It is necessary because lot of open dumping areas that are left abandoned without the proper mitigation [1].
Integrated Risk Based Approach (IRBA) was first used as a decision making tool in the location of Perungudi (PDG) and Kondungaiyur (KDG) in the city of Chennai, India where the calculation obtained the value of RI in the location of PDG of 569 and the location of the KDG 579 [2], [3]. Meanwhile, in the location of Eneka, Nigeria research obtained the value of RI 452,3 [4]. Other studies at Igbatoro landfill [5] have been found that the impacts include high health and environmental risks and the degree of silence on the impact of communities, where the risk index (RI) value gained is 571,58. Rehabilitation landfill needs to be carried out due to soil pollution in the landfill area is usually polluted by leachate [6].
Cahaya Kencana landfill apparently has leachate contamination in the sanitary landfill area with the resistivity value of soil tainted in the range of 1,50 -4,34 Ωm at a depth between 0,75 meters to 13 meters [7].

A. Description of the Studi Site
The research location is located at Cahaya Kencana landfill at Lihung village, Karang Intan sub district, Banjar district, province South Kalimantan. Where for the retrieval of loose garbage samples is garbage truck that comes from Sekumpul street, while for the sampling of solid waste samples derived from sanitary landfill area. Location of Cahaya Kencana landfill located at 03 O 27'29.0" Southern Latitude (SL) and 114 O 55'28.2" East Longitude (EL). Figure 1. explains the location of this research.

B. Risk Assessment
Risk Index/ RI calculated with this formula [3]- [5]: Where: Wi = Weightage of the with variable ranging from 0 -1000 Si = Sensitive index of the with variable ranging from 0 -1 RI = Risk Index variable from 0 -1000 Risk Index (RI) can be used for classification of landfill sites to be closed or rehabilitated. A value of 0 indicates no or less danger, a value of 1 indicating the highest potential danger. The higher the value indicates greater risk to human health and the actions that must be taken immediately at the site of landfill. The next priority decreases with the total decrease in value. Lowest values indicate low sensitivas and small environmental impacts. Hazard-level evaluation criteria based on the risk index value of landfill can be seen in table 1.

III. RESULTS
The measurement of maps with ArcGIS 10.2 software is derived data that the closest water source used in operational and maintenance activities in Cahaya Kencana landfill site is the river used for irrigation with the closest distance is 967 meters ( pebble sand, which can be assumed as a rough sand that has a permeability value between 1-0.01 cm/sec [9]. Distance Cahaya Kencana site with conservation forest or critical habitats that is the education forest based on Banjar district spatial plan year 2013-2032 is 2.205 meters (2,2 km) (  Accumulation rate uses 2,75 liters/person/day according to the major city classification [11].
The level of garbage in sanitary landfill in Cahaya Kencana site is 10 meters high with land area of 8089,73 m 2 . The results of future landfill age are obtained 1 year or until year 2021. While based on the results of the community kuisoner, it is obtained that the average community as much as 60% received the existence and rehabilitation of open waste landfill.
Laboratory test results obtained leachate results for the BOD parameter has value of 210 mg/L, COD has value of 501,73 mg/L, and the TDS has value of 2.254 mg/L. Solid waste moisture content is 58,23%. Quality of water well in Cahaya Kencana site can not be used as a source of drinking water. Because the parameter of hardness water has a value of 1444,20 mg/L, E. Coli as much as 1,3 x 10 3 amount/100mL Through Table 4. we can perform optimal processing efficiency on each pond, with a modification design. For example for anaerobic pond lenght, the comparison is 1/5, so the existing pond can be blocked into 5 parts. So that leachate can be processed optimally according to the hydraulic retention time (HRT). This also applies to each other pond with the addition of the connecting floodgates of each partition. This water door can be opened at the time of the

IV. CONCLUSION
Risk Index (RI) assessment results using IRBA obtained 524,007 value with a category of moderate hazard evaluation, so that Cahaya Kencana landfill site can be forwarded and rehabilitated into controlled landfill gradually. Leachate treatment unit can be design modification, so that the resulting effluent will be in accordance with the quality standards that have been set.