Trends and Sustainability of Groundwater in Highly Stressed Aquifers (Proc. of Symposium JS.2 at 193 the Joint IAHS & IAH Convention, Hyderabad, India, September 2009). IAHS Publ. 329, 2009. Integrated assessment of risk for contaminated sites due to on- site sanitation systems in mining area, Karnataka, India H. K. RAMARAJU University Visveswaraya College of Engineering (UVCE), Jnanabharathi Campus, Bangalore University, Bangalore-560056, Karnataka, India [email protected] Abstract The sanitation coverage in rural households of India is very low. A field study was carried out in the Kolar Gold Field mining residential area. The residents of the study area depend on bore wells and resort to septic tanks for disposal of domestic waste. The main objective of this study is to assess the impact of septic tanks/low cost sanitation systems on groundwater and soil environment in the unsaturated zones of the soil. The hydraulic conductivity of the soil in the study area varied from 0.13 to 0.31 m day-1. Higher concentration of nitrates and chlorides in well waters show that groundwater is getting contaminated with on-site sanitation effluents. Higher concentrations of major metals, salts and gases were also observed because the geology of the particular area has influence on the quality of water. Based on the investigations, appropriate technological options are proposed. Key words bacteriological; hydrogeological; infiltration; nitrification; onsite sanitation systems; unsaturated zones; weathered rock INTRODUCTION Water for human consumption is perhaps becoming more vulnerable due to various strains on its qualitative and quantitative counts. Different types of pollution are making the issue more complicated and costly for mitigation. The sanitation aspect has to include a lot more issues, rather than only emphasising the construction of sanitary latrines. Even sanitary latrines require extensive post-surveillance on their proper upkeep and use. The issue of proper drainage systems for liquid waste conveyance (for processing) is another area which warrants improvement. There are also various other components of sanitation which are required to be dealt under one comprehensive management programme. The next hazard is the dust from the “Mill Tailing Dumps” all around Kolar Gold Field (KGF) called “Cyanide Dumps” because of their content of cyanide used to extract the gold from the ore. The continuous mining activity of the last 100 years in this area has resulted in the accumulation of huge dumps of mining waste (mill-tailings) occupying about 10% of the total land in the township; these tailing dumps rise to a height of about 30 m from the ground. Now the general public of all age groups have been affected by the cyanide dust which is spreading all over the KGF. The cyanide spill occurred in an area already stressed, deteriorated and contaminated with heavy metals from historic mining and mineral processing operations. Similar cyanide spills and tailings dam failures are likely to occur in the future (Lottermoser, 2007). The pressure of our growing population and the increasing affluence of our society have resulted in more and more people buying home sites in the relatively isolated areas. These home sites often require individual wells and sewage disposal systems. In many rural and suburban or old developed towns, especially in developing countries, like India, sewer-less sanitation would appear to be the only feasible and appropriate method of providing on-site sanitation. Septic tank systems/cesspools/pit latrines are low cost sanitation systems used for the disposal of domestic wastes in these undeveloped areas. Septic tanks are reported to be the major contribution to groundwater contamination. The existing septic tank system, developed nearly a century ago, has many functional inadequacies. Their performance depends on their design, construction, nature of wastes, climate, regional geology, topography, physical and chemical composition, nature of soil mantle, and care taken in periodic maintenance (Chen, 1988). According to the World Health Organisation (WHO) report “at least 2.5 billion people in developing countries lack an adequate system for disposing of their faeces”. The present study aims at checking environmental conditions to assess the extent of contamination from on-site sanitation systems. Copyright © 2009 IAHS Press 194 H. K. Ramaraju A field study was carried out in the KGF mining residential area in the district of Kolar. The field investigation was limited to the 23 blocks/areas, where the sewerage system is non-existent. The migrants from the study areas depend on bore wells/tankers/piped water supply and resort to septic tanks/cesspools/pit latrines/open defaecation for disposal of domestic wastes. A majority of the disposal systems are faulty designs and their performance is far from satisfactory. BACKGROUND Kolar Gold Fields has been famous for its ore exploitation since the end of the 19th century. However, in the late 1980s, the mine activity began to decrease due to a progressive increase of the production cost, connected to several factors (geological, managerial, socio-economic). Eventually, the mine exploitation was put to an end in 2001, leading thousands of former employees and their families to hardship. The women living in the KGF mining area are specifically concerned with access to water, community toilets, and with domestic waste management. Since the closure of the mine in 2001, the services under the responsibility of the mining authorities have been stopped. In the rural area of Bangarapet and Mulbalgal taluks, people affiliated to Kolar Gold Fields Women’s Association (KGFWA) are requesting improvement of access to water. It means that operation and maintenance systems have to be developed in order to allow the beneficiaries to take its responsibility (at some locations in partnership). In order to provide an adequate sustainable access to basic services to the requesting people, a technical feasibility study was carried out. OBJECTIVE OF THE STUDY This study is the result of a request coming from ADER (an NGO-non-governmental organization), France. Indeed, since the closure of the mine in 2001, the provision of water and all the social services for the KGF town families, guaranteed before by the mining society, have been stopped, e.g. the operation and maintenance of the public toilets. Therefore, the toilet infra- structures have slowly deteriorated. Since 1999, ADER has been supporting access to basic services project requested by its partner KGFWA. Thus, experience has been achieved in toilet repair/renovation; 50 community toilets were renovated during 2003–2005. At the same time, a sanitation awareness programme has been implemented towards the families who took responsibility for the operation and maintenance of the community toilets. The main focus of the technical feasibility study is to assess, at each location, to what extent the toilet use is eco-friendly and assesses the impact to the groundwater and preservation of natural resources. DESCRIPTION OF THE STUDY AREA Kolar district is known worldwide for its rich gold deposits. It is bound by north latitude from 12°46′ to 13°56′ and east longitude from 77°21′ to 78°35′. KGF is situated at 12°57′ north and 78° east in the southeast corner of the Kolar District of Bangarpet Taluk in the State of Karnataka (Fig. 1), at the tri junction of Andhar Pradesh, Tamil Nadu and Karnataka. Mean annual temperature is around 23.8°C. KGF lies in the rain shadow area where average rainfall per annum is 820 mm, the population of KGF is 3 lakhs, as per 2001 census. The mining area has a population of 1.5 lakhs. The mining area, which is owned by Bharat Gold Mines Limited (BGML) a Government of India Enterprise, has 4900 ha (12 253 acres) of land, of which approx. 1600 ha (4000 acres) are in use. Karnataka Urban water Supply and Drainage Board has a reservoir at Bethamangala, 10 km away from Kolar Gold Fields. The plant capacity is 8494.34 million litres. Bharat Earth movers Limited (BEML), manufacturer of earth-moving equipment, is located at KGF and requires 10 lakh litres per day. A number of bore wells have been installed to augment the water supply. The KGF area is covered by red sandy soil, with light texture varying from sand or gravel to loamy, and is highly leached. Integrated assessment of risk for contaminated sites due to on-site sanitation systems in a mining area195 Fig. 1 Location map of Bangarpet Taluk, Kolar District. KGF town consists of an immense expanse of gneisses classified as Peninsular gneisses, and granites of different phases with green stones, dolerite and amphibolite dykes. The quality of the groundwater is governed by the mineralogical composition of the rocks. In the absence of major sources of water like rivers, the KGF depends heavily on groundwater. But the groundwater table has receded beyond 200 m depth. Hence most people get their drinking water from outside town and only use local water for non-drinking purposes. Some make trips to nearby safe sources (1–4 km) to get a can of drinking water. The localities are using bore well water for non-domestic purposes. Few bore wells are supplying water for other nearby wards. The geology of the particular area has a tremendous influence on the occurrence and quality of water, and its movement in the zone of saturation below the surface. The chemical constituents present in groundwater are derived generally from the geo-environment in which they occur and the anthropogenic activities. The common constituents found in water are suspended impurities like bacteria, algae and silt/clay, dissolved impurities like salts (Ca, Mg, Na), metals (Fe, Mn, Pb), gas (O2, CO2, H2S and CI) and organic matter; few water samples from bore wells of various wards were collected to study the quality. METHODOLOGY OF INVESTIGATION Physical site surveys were carried out during October 2006 to know the status of on-site sanitation systems and to select sampling points for water and soil collection.