i) The field visits were undertaken for assessing the water resources of Sirigaon village in the months of August’08, October 08’ and December 08’. Inspection was made for design and implementation of the recharge structures for augmentation of water resources in the month of January 2009. The field observation indicate that very less water (2-3 m water column) is present in the wells in the months of August and October. All the wells in Sirigaon village had gone dry in the month of December 2008.
ii) The mining activity has led to loss of capping material and at present the bottom of the mine pit has gone below (-20m) for all the three Minng companies.
iii) The ground water level (amsl) contours indicate that the groundwater flow direction is towards the mine pit. Seepage to the pit from the mine wall was also observed during the field visits which may lead to decline of water resources in the Sirigaon village.
iv) Water analysis from the dry wells and mine pits indicate that the quality is suitable for domestic water needs after conventional treatment as well for irrigation after proper sedimentation to avoid suspended matter.
v) It is essential to initiate groundwater recharge activity in a comprehensive and scientific way to recharge the aquifer as well arrest the flow to the mine pits from the aquifer. A comprehensive recharge scheme is accordingly recommended with a framework for implementation. Post-project monitoring needs are included in the overall recharge scheme. The post-project monitoring can be undertaken by NEERI in a project mode for three years.
vi) The findings indicate that silt accumulation has taken place in the neighboring agricultural land and soil fertility has been impaired. The restoration of the degraded land by Integrated Biotechnological Approach (IBA) has been suggested and the cost estimates are made in this regard. The silt accumulation in the agricultural field is caused by the run-off from the overburden dumped material during the monsoon season. Therefore, slope stabilization needs to be carried out to minimize the run off.
vii) The rooftop harvesting structures (60 Nos.) will cost an amount of Rs. 34 lakhs. Construction of recharge wells (60 Nos.) and water absorption trench is estimated at Rs. 73 lakhs. The third priority of construction of subsurface dyke and bentonite grouting will need Rs. 410 lakhs as capital cost. Other costs involved are preparation of Detailed Project Report (DPR), maintenance of the structures and monitoring of the environmental management plan
viii) The total cost of all the priorities for recharge scheme is estimated at Rs. 660 lakhs and the rejuvenation of silt affected soils needs Rs. 1.8 lakh/ha of the land. The cost estimates are based on the present (year 2008 SOR of Govt. of Goa) price level