Effluent Disposal

Effluent Disposal From Thar Coalfields

  • Name of Scheme: Construction of 50 Cusecs Drainage and Waste Water Effluent Channel from Mining Area of Thar Coalfield Block No.II.
  • Scope: In order to initiate mining activity in Thar, there is need of appropriately sized effluent disposal system. It has been assessed by RWE that bottom aquifer will involve disposal and pumping of about 25-30 cusecs from a mine of size 6.5mtpa. In addition, 5-7 cusecs of effluent shall also be generated by power plant of size of 1000MW. Thus, it is expected that Thar Coal fields require a robust effluent disposal system for disposal of at least 50 cusecs of effluent for initial projects.

For the purpose of Construction of 50 Cusecs Drainage and Waste Water Effluent Channel from, Mining Area of Thar Coalfields, the PC-II has been prepared so that the feasibility Study may identify and confirm source of disposal for waste water and effluent drainage to fulfill requirements and the mechanics, to dispose of the same or to reused for irrigation purposes at Vajihar.

The PC-II has been approved by PDWP amounting Rs. 15.979 million and the Sindh Irrigation and Drainage Authority (SIDA) has been assigned the task to complete the Feasibility and prepare PC-I within two months.

A preliminary survey and hypothetical analysis shows that there are a limited number of options available where and how to dispose effluent Water into the natural hydrological system. The common option is to return the water either to the land, local water ways and lakes, or to salt sinks, such as the ocean. The following are the possible option.

1. Treatment of effluent and use of water within and the outer proximity of Power Plant.

2. Develop an effluent retention pond/ponds battery sufficiently beyond the Power Plant activity area with the perspective that equilibrium is obtained between effluent quantity and natural evaporation cum infiltration.

3. Option 2 above but with installation of evaporation accelerators (sprinkling upper layers of brackish water into air under controlled mechanism)

4. Conveying effluent to agricultural area and using partially treated effluent for agriculture and other appropriate usages – Agriculture-forestry system and solar evaporators.

5. Conveying and pouring effluent through gravity flow into similar water quality vast water body i.e. Rann of Kutch

6. Option 5 above but with provisions of small supporting intermediate retention evaporation ponds.

7. Conveying and disposing effluent into nearest brackish water flowing stream i.e. Left Bank Outfall Drain

8. A combination of options 1, option 2 and option 4 whereby portions of effluent are utilized through permutation and combination.

9. Deep well injection of effluent into the aquifer.

Option-5: Conveying and pouring effluent into gravity flow connected similar water quality vast water body.

This option was investigated during preliminary field survey in order to adopt safe and economical alignment as per social/ environmental constrains, initially the GIS model desktop study concluded various possible alignments by following natural contours from Block-II to Ran of Kutch, as the general topography of the area didn’t permitted for continues gravity flow due to series of high dunes ridges ranges from 370- 200 ft, Therefore the alignments filtered on contour constrains by considering the following controlling factors.

1. Accessibility through existing infrastructure of roads/ natural trails/ tracks.

2. Possible gravity flow by compromising length increase.

3. The minimum damages to local Traies, Dug wells and other water resources.

4. Keeping the alignment away from the agriculture land as much as possible.

Therefore it is proposed the alignment off-takes from Block-II effluent line which contain combine waste water attends contours of 200 to 300 ft, through pressure pipe line in total length of 11.92 miles with intermediate transition tanks and pumping station arrangement, as cumulative lift of 100 ft excluding pipe line losses. The remaining section of pipe line attended continues gradient from 170 to 70ft with total length of 14.65 mile) upto proposed outfall into Dharm ran pat of run Kutch Pakistan territory, which is a natural depression connected to active seer sea creek system highly saline water body.