International Journal of Advanced Science and Technology Vol. 29, No. 7, (2020), pp. 2375-2382 Geochemical Evaluation of Contaminated Soil for Stabilisation Using Microbiologically Induced Calcite Precipitation Method [1]Jodin Makinda, [2]Khairul Anuar Kassim, [2]Kamarudin Ahmad, [2]Abubakar Sadiq Muhammed, [2]Muttaqa Uba Zango [1],[2] School of Civil Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, 81310, Skudai, Johor Malaysia [1] Faculty of Engineering, Universiti Malaysia Sabah, 84000, Kota Kinabalu Sabah, Malaysia Abstract Abandoned mines contaminated with heavy metal wastes pose health risk and environmental hazard. Common methods in managing these wastes include pond storage, dry sacking, underground and ocean disposal and phytho-stabilisation but these does not address the associated risks regarding migration of contaminated liquid or when the soil structure is compromised during natural disaster such as earthquake. Due to these limitations, microbiologically induced calcite precipitation method (MICP) is an exciting alternative as it is sustainable and environmentally friendly. This research evaluates mine waste obtained from two sites; Mamut and Lohan Dam, both located at earthquake-prone Ranau Sabah, Malaysia, in term of their physical, mineralogy and morphological characteristics for stabilisation using MICP. Physically, mining wastes from Mamut are of well graded soil with sand (53.9%) and gravel (43.5%), classified as SW (USCS) and A-1-a (AASHTO). Meanwhile, waste from Lohan Dam are of sand (49.9%) and gravel (10.1%), classified as SM (USCS) and A-4 (AASHTO). Constant head test of the soils from the sites showed results of 3.607 x 10-1 and 3.407 x 10-2 cm/s respectively indicate high permeability. Mineralogy assessment using inductively coupled plasma atomic emission spectroscopy (ICP-OES) showed high level of iron (Fe) with 528.08 and 2931.38 mg/L respectively. Other heavy metals detected include copper (Cu), 24.39 and 4.33 mg/L, lead (Pb), 2.53 and 0.53 mg/L, manganese (Mn), 5.71 and 3.64 mg/L and arsenic (As), 0.71 and 0.31 mg/L; some higher than Malaysia’s Ministry of Health and United Nations’ Food and Agricultural approved standards. Morphological observation of the size, shape and soil texture under scanning electromagnetic (SEM) further indicate the necessity and suitability of both sites for stabilisation using MICP. Index Terms—Contaminated Soil, Microbiologically Induced Calcite Precipitation, Mine Waste, Soil Stabilization I. BACKGROUND, MOTIVATION, OBJECTIVES In 1970s, Malaysia was one of the world’s leading countries in minerals production of tin, copper, bauxite, gold and ilmenite. Indeed, mining was one of the major contributor to the GDP, producing almost 31% of the world tin output in 1979 but the production fell by 90% over the last 15 year [1]. Due to the exhaustion of mineral deposits, low prices and high operating costs, many of the mines are now abandoned include sites in Bukit Botol, Bukit Ibam, Panching, Sg Lembing, Kota Gelanggi, Padang Piol and Kg Awah in Pahang [2] and Mamut in Sabah [3]. Heavy metal wastes from abandoned mines are known to pose health risk to the surrounding settlement and potential hazard to the environment. For example, Mamut cooper mine which was in operation from 1975 to 1999 generated about 350 Mt of waste, of which 250 Mt are rocks and overburden materials and over 100 Mt of tailings. The wastes from this mine were dumped at various sites near the areas [4]. Compared to other developing countries, Malaysia has not inherited such a serious legacy of contaminated land and most of the identified possible sources of contaminations come from motor ISSN: 2005-4238 IJAST 2375 Copyright ⓒ 2020 SERSC International Journal of Advanced Science and Technology Vol. 29, No. 7, (2020), pp. 2375-2382 workshops, petrol stations, fuel depots, railway yards, landfills, industrial sites and ex-mining land. Probably due to this, little works have been carried out in identifying and stabilizing contaminated lands. Currently, most methods in management of wastes include pond storage, dry sacking, underground disposal, ocean disposal and phytho-stabilisation does not address the associated risks regarding migration of contaminated liquid or when the soil structure is compromised during natural disaster such as earthquake. Other approaches on remediation of contaminated mine waste are by using stabilizers to bind the waste particles thus immobilizing the contaminants and minimizing leaching into the surrounding environment. Among the previous studies include immobilization of sulfates and heavy metals in gold mine tailings by sodium silicate and hydrated lime [5], treatment of acid mine drainage using limestone and activated sludge [6], stabilization of arsenic with basic oxygen furnace [7], phosphate treatment for the remediation of contaminated mine waste [8], application of coal combustion by-products in mine site rehabilitation [9], use of clay liners, whose essential material is bentonite to decrease the hydraulic conductivity of landfills [10], Portland cement application to control acid mine drainage generation from waste rocks [11], use of fly ash for backfilling abandoned room and pillar mines [12], use of Si-rich substances to regulate the mobility of pollutants in soil and water and enhance the plant resistance to its toxicity [13] and use of serpentinite and concrete waste to raise pH level and removing metal ions concentrations from acid metal drainage [14]. However, question is still arising on the use of these industrial based by-products as they alter the pH of groundwater and thus may cause serious environmental problems and contribute to the ecosystem disturbance [15]. Since MICP is considered as newer, more inventive and environmentally sustainable compared to the other methods, a wider application of this technique in geotechnical engineering should be explored. MICP is a biologically driven calcium carbonate (calcite or CaCO3) precipitation technology, either controlled or induced. When it is biologically controlled, organism independently synthesizes minerals unique to the species regardless of the environmental conditions while induced mechanism produces CaCO3 somewhat dependent of environmental condition[16]. The factors affecting the effectiveness of the treatment include type of bacteria, treatment method, temperature, bacteria concentration, pH, degree of saturation and most importantly the geochemical properties of soil [17]. This research reports the preliminary geochemical evaluation made on mine wastes collected from several points near abandoned Mamut Copper Mine, Ranau, Sabah, Malaysia shown in Figure 1. While MICP is gaining popularity to treat problematic soil such as liquefaction, internal erosion, settlement and frost damages, its potential in treating contaminated soil, particularly of mine waste is still not explored fully. The research is motivated by the increase in land contamination in Malaysia and particularly in the study area, some infrastructures were reportedly damaged due to a 6.0 magnitude earthquake on 5th June 2015, causing ground failure and rising fear of wall of open pit in abandoned mines breaking, causing water to flow out to the water resources utilised by nearby residents [18]. II. MATERIALS AND METHODS A. Materials Sampling was conducted near the abandoned Mamut mine and Lohan Dam about 8 Km away where the tailings were piped, routed and deposited. The GPS coordinates for both locations are as shown in Table 1. Table 1: Sampling Locations Sample Location Mamut 6°1′ 37.7″ N, 116°39′ 21.0″E ISSN: 2005-4238 IJAST 2376 Copyright ⓒ 2020 SERSC International Journal of Advanced Science and Technology Vol. 29, No. 7, (2020), pp. 2375-2382 Lohan Dam 6° 0' 45.936'' N, 116° 44' 20.004'' E The samples were collected at depth of 0.5 m to 3.0 m of the soil profile and submitted to Geotechnical Laboratory, Universiti Malaysia Sabah for geotechnical tests. Figure 1: Location of Study Area [19] B. Geotechnical Test The geotechnical properties determined were their natural moisture content, sieving analysis, Atterberg limits, pH, specific gravity and organic matter. Dry and wet sieving method was used to determine the particle size distribution of coarser and finer soil respectively. pH was measured by pH meter and specific gravity, permeability and organic matter were measured according to British Standard. Following the tests, the mine wastes were classified based on their particle size, particle distribution and texture using two major classification systems; AASHTO and USCS. All laboratory tests were performed at according to BS 1377: Part 2: 1990. C. Mineralogy Test The air dried and powdered sample were then made into pressure, digested and analysed using inductively coupled plasma optical emission spectrophotometer (ICP-OES) to determine the concentration of heavy metals and major elements. All mineralogy and morphology tests were performed University Industry Research Laboratory, Universiti Teknologi Malaysia. D. Morphology Assessment A scanning electron microscope (SEM) with a maximum magnification of about 1000x were used to generate high-resolution images and precisely measures very small features on the surface of the soil sample. III. RESULTS, DISCUSSION AND CONCLUSION A. Geotechnical Properties Table 2 and Figure 2 show the geotechnical properties and gradation curve aof both Mamut and Lohan Dam soil. Based on the particle size distribution, Mamut contains 97.4% coarse grain compared to 60.0% for Lohan