Draft Water Safety Plan
Kandana Water Treatment Plant
Catchment and intake
Surface water: Kalu Ganga
Capacity (Max.):60,000 m3/day
• Kalu Ganga is the second largest river basin (2719 km2), starting from central hills (2250m) and running across the wet zone.
• Main sources of water of the river are mountainous forests in the central province and the Sinharaja Forest Reserve.
• Largest amount of water (4000 m3) is discharged to the sea at Kalutara after travelling across Sabaragamuva (Ratnapura) and Western (Horana, Mathugama, Kalutara) provinces (129km).
• Upper part of the basin has steep slope and lower part has mild slope.
• Upper part of the catchment is highly affected by intensive cultivation of permanent export crops (Tea, Rubber, etc.) and urban centres.
• Middle part is flowing through well populated urban areas and export crop cultivated areas.
• Lower part is mainly affected by paddy cultivation and also it is affected by flood due to hydrological and topographical characteristics of the basin during southwest monsoon season.
o Extensive clearing of natural vegetation
o Using agrochemical and various chemical manures
o Dumping urban solid waste
o Encroachment of Reservations
o Gem Mines & Washing
o Sand Mining
Total capacity of Kandana Treatment Plant is 60,000 m3/day.
• 500,000 populations are serviced and supply areas are Horana, Bandaragama, Panadura, and Moratuwa.
• Water abstraction point is Kandana.
• Conventional treatment process is processed.
Typical Hazards and Hazardous Events Identification
|Hazardous Events |Hazards | |Meteorology and weather patterns |Flooding | | |rapid changes in source water quality | |Seasonal variation |Changes in source water quality | |Mining |Deterioration of water quality | |Sand Mining |River bank erosion | |Gem Mining & washing |Lowering the river bed level | | |Blocking the flow paths of the drainage | |Agriculture |Microbial contamination, Pesticides, Weedicides, Nitrate, Phosphate | | |Slurry and dung spreading | | |Disposal of dead animals | |Forestry |Pesticides, PAHs-poly aromatic hydrocarbons(fires) | |Industry (including small scale and |Chemical and microbial contamination | |sites) |Potential loss of source water due to contamination | |Transport-Roads and Railways |Pesticides, Chemicals...