Leachate in L F Leachate can be defined

Leachate in L. F Leachate can be defined as liquid that has percolated through. S. W and has extracted dissolved or suspended material from it (S. W) It composed of: 1. Liquid that has entered the left from external source (surface drainage, rainfall, G. W). 2. Liquid produced from the decomposition of the wastes. In its movement through S. W, both chemical and biological constituents are picked up and the pollutant contents in atypical leachate as shown in table. Constituent BOD(mg/l) TOC COD TSS PH value Alkalinity Org (N) (mg/l) rage 2000 -30000 15000 -20000 3000 -45000 200 -1000 5. 2 -8. 5 1000 -10000 10 -600 typical 10000 6000 18000 500 6 3000 200 The quantity of leachate formed in a L. F is a function of the amount of external water entering the L. F. Leachate quantity depends on the following factors: 1. Final cover material (carefully graded) and permit runoff without causing erosion. 2. Surface slope to provide and accelerate runoff (2 -4%). 3. Type of vegetation cover and amount. 4. Permeability of cover material. 1

5. Settlement of cover material. 6. Surface drainage around fill area. Gas and leachate at Movement and Control: The gas generated in L. F Should be either 1. Vented to the atmosphere or. 2. Collected for the production of energy ( in large L. F sites). The leachate should be either: 3. Contained within the L. F. 4. Removal for treatment. Gas Movement: Over 90% of the gas volume produced from a L. F site consists of and When gas present in the air concentration between 5 -15% it become explosive (due to present of However there is no ) in a L. F when concentration reached this critical level and so no danger of L. F will explode. - Most of the methane gas escape to the atmosphere sine its density is lower than that of and the air (density that of of COdensity - But lateral movement of was observed at 400 ft from the edge of the fill area. 2

- For unvented L. F the extent of lateral movement depend on the characteristics of the cover material and surrounding Soil. - This may lead to accumulation of the gas below building and close to sanitary L. F. - gas is denser than air (1. 5 times and 2. 5 timesas dense as ) So it tend to move to bottom of L. F and even to the under laying formation unit it reach the under ground water, as is heightly soluble in water, it lower the PH and increase hardness and mineral content of g. w as follow: 3