Herald: River Sal in the ICU

River Sal in the ICU

03 Mar 2019 06:54am IST

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03 Mar 2019 06:54am IST

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The river Sal, Goa’s very own river is identified as polluted by the Central Pollution Control Board and this has been caused by sewage discharge by the urban population, cattle washing, solid waste dumping to cite a few reasons. SHWETA KAMAT takes a close look at what are the problems on the ground

River Sal is amongst those 11 rivers that are identified as polluted by the Central Pollution Control Board (CPCB). Considered a lifeline of South Goa, River Sal, is today struggling to exist owing to severe pollution. Sewage discharge by urban population, cattle washing, solid waste dumping are major issues the River is facing, which are caused due to habitation across the river bank. River water is not anymore safe for bathing, fishing or other recreational activities. 

Sal, which is Non-perennial River travels almost 40 Km stretch till it discharges in to Arabian Sea at Mobor. The river flows through urban areas like Verna, Margao, Navelim, Benaulim, Varca, Orlim, Carmona, and Dramapur before it discharged into Arabian Sea. CPCB has classified Sal River (from Stretch Khareband to Mobor) under priority III, having BOD (bio-chemical oxygen demand) level range between 10-20 mg/lit. Almost 22 kms of the river stretch is polluted. 

Following directions from the National Green Tribunal (NGT), the State government constituted a River Rejuvenation Committee (RRC) under the Director Environment, who has prepared a detail Action Plan for the river, after conducting detail study with pollution source identification, possible corrective and preventive actions on short term and long term basis. The committee has proposed Es Rs 47.44 crore rejuvenation plan for the river. 

Brief summary of the Findings 

It is observed that, the parameters like dissolved oxygen (DO) content and the Bio-chemical Oxygen demand (BOD) are well within the prescribed limits throughout the season except in May and September in each year. However, the fecal coliform and total coliform count was found to be higher side at upstream of river, due to discharge of untreated pollutants in river, as well as lack flow of river of fresh water. As the river flows towards the Arabian Sea, the faecal coliforms and Total coliforms values come down well within the range (but not in prescribed limits for use it bathing water). 

Action Plan in two-phased 

Immediate Phase (Short Term)- The budgeted Cost for immediate phase/ short term includes De-Silting, Sanitation facility, Natural Stream Protection. 20.39 Cr. 

Intermittent Phase (Long Term) - This includes the recycle and reuse of the recycled water from the existing STP and Solid waste treatment at a total cost of Rs 27.05 crore. 

Findings and Observations on Testing 

The results of the water sampling are observed from various perspective in order to define the action plan strategies. 

. The parameters like dissolved oxygen content and the Bio-chemical Oxygen demand are well within the prescribed limits throughout the season except in May & September in each year.

. The higher values of BOD are because of the higher temperature and the untreated domestic effluent discharge in river water. The Higher BOD are recorded near Khareband Bridge as there are some natural outfalls observed in the vicinity. 

. As the river flows towards the Arabian sea, the fecal coliforms and Total coliforms values come down well within the range (but not in prescribed limits)

. The river stretch is about 22Km, out of which the 14Km stretch (i.e. up to Navelim and further down up to Hawai Garden). 

. The 70% of the polluted stretch is under the influence of the tidal effects resulting the variation in the parameters. 

. The seasonal variations are observed in the values of faecal coliforms and the total coliforms, the values are higher in monsoon and are lower in other season.

. The DO level are inversely proportional BOD values. It is necessary to revalidate the sampling and testing methods during the Month of Dec 2018. 

. The TC & FC values show high seasonal variance. The FC & TC in Dec. 2018 are very high and it will not be rational to consider these values for defining the strategies for Sal River Action plan 

. The BOD & DO levels can be well within the desired limit with appropriate planning and mechanism in place. Hence it is appropriate to define the action plan strategies in order to control the faecal coliform and Total coliform. 

. The Design concept and Action Plan approach has been defined considering the FC values as 35000 and TC values as 54000 (Nov -2018 values). The higher values (recorded up to FC-54000 & TC-92000) are not considered as these results are observed only twice in last 5 years span.

Action Plan Strategies 

The Sal River is one of the major river stretches in the state. This river stretch is the most polluted stretch and the only stretch which falls under priority III. It is essential to plan for the multi-stakeholder tributary approach for river rejuvenation. The action plan strategy has been defined based on the present status of the river, the results obtained during the monitoring and long term sustainability of the project in order to achieve the desired standards. 

Sources of the pollutants (Situation & Problem Identification): The entire stretch was studied from the pollution, tidal and eco-sensitive aspects. The river is entirely rain fed river and does not fall in the perennial river stretches. 

. The river system is receiving the major quantity of surface runoff from the urbanised area in Madgaon & Verna towns. 

. The other possible source of the pollutants is discharge from the Verna Industrial Areas which is not clearly identified as the river is not accessible in the vicinity. This can be observed from the water flowing near Seralim Road Bridge. As the river flows in the urbanised area (further downstream), the untreated domestic effluent from the Margao city is discharged in to the river. 

. Two STP’s are located along the bank of the river having capacity 20 MLD & 7.5 MLD respectively. Both the STP’s are functioning and outlet parameters is been monitored and maintained in the prescribed limit. 

. The sewerage system is laid along the river is more than 30 years old and having several leakages. The domestic effluent from all residents might not be connected to the municipal sewer and directly discharged into the river.

. Open defecation from the residents along the bank is also the major source of the pollutants. The domestic animals washing, is also observed on the downstream of Margao

. The development / human settlement along the river stretch and discharge of the domestic effluent is the major source of the pollutant along the stretch on downstream of Margao

Identified points of pollution with cause 

. The higher BOD are observed along the urbanized areas of Madgaon which are justified by mixing of untreated sewage in river.

.  The domestic effluent is been discharged in to the river downstream of Khareband Bridge

. The natural outfall is polluted due to the domestic effluent discharge from unauthorized connections. 

. The effluent discharge from the slaughter house is discharged in to the river through the storm water drain. These outfalls are to be identified and connected to municipal sewer network, after localized treatment. We will issue directive to localized treatment of water from slaughter house before releasing into water body

. The solid waste is disposed along the bank of the river at many locations

.The road development and the bridge construction work is in progress. The river flow is diverted for construction facility. The water stagnation is observed on the upstream side due to flow diversion. (Near Navelim bypass)

. Natural outflow near Navelim STP

. The domestic effluent is discharged in Navelim area.

. Sewage Discharge from Telaulim & Sirlim Village:

. The domestic effluent discharge from the Kankanmoddi and the surrounding areas are the source of the pollutants in this vicinity.

. The solid waste dumping near Orlim Bridge is observed. The tourist and the residence are dumping the plastic and glass bottles.

. The dead / waste fish been discharged in to the river causing the sources of pollution near Mobor Jetty.

Major Concerns: The ground water sampling also need to be conducted in the river stretch in order to define the action plan strategies. Apart from the domestic / industrial effluent, chemical runoff from the field is contributing to the water quality problems as non-point source pollution. 

Apart from water quality issues, non-availability of flowing water is also problematic in the Sal basin throughout the season. Inefficient water usage patterns in domestic, industrial and agricultural sectors are contributing to the water quality problems of the River. 

Being a non-perennial river, it is sluggish throughout the year except during high flow periods during the monsoon season. This seasonal variation reflects that river water composition is influenced by annual cycles. 

Biological and geological breakdown in the summer season leads to the accumulation of chemicals during the dry session, followed by dilution of those chemicals by monsoonal rainfall. The river flows are disturbed at many places due to the development and encroachment in the vicinity. 

The geological formation in the Deccan Plateau is the major concerns of the river rejuvenation. The sewerage system is not in place and the Septic tanks are located close to the river bank and the tidal effects in the vicinity. 

The seepage of the overflow may lead to the surface water from the joints of the laterite. Based on the above observations, following action points are proposed.

Conclusion & Remark: 

. The river stretches within the state are different than the other river stretches within the country. The travel distance of the Sal River is 40km and it originates on the hillock on eastern side. 

. The river stretch is polluted mostly due to the urbanization on the either bank & inefficient Sewerage collection conveyance & treatment mechanism. 

. Public participation involvement of all the stake holders (like Environment Department, State Pollution Control Board, Public Works Department, Directorate of Municipal Administration, Urban Local Bodies and Social Welfare Department of the State of the Goa) is essential to make this mission successful. 

. The State Government shall establish the mechanism with responsibility entrusted to the respective department. 

. The State Government shall form the authorized committee with all the stake holders, residence from the local areas, Urban Local Bodies, Health Department for long term suitability of this project. 

. The success of the proposal will be dependent on the comprehensive action by the various State department like Water Resources Department, SIDCGL, PWD, DMA & ULB. The estimation and the items considered for the Action Plan shall be thoroughly checked by the respective department. The respective department will take appropriate action, feasibilities analysis of the proposals, detailed estimate and execution of the work in a stipulated time frame
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