Landfill Leachate- Groundwater- Proof read

There is a danger of contaminating groundwater sources especially in
unlined landfills since the leachate could reach the water table. Once
groundwater is contaminated, health and environmental risks will occur.
Therefore, leachate control in landfills is an important aspect of
municipal solid waste management. Leachate within the body of a landfill
site is rarely static. Water enters the landfill principally as rainfall
infiltrating from the surface, but in some cases also as surface or
ground water inflows (Appendix A). Any resulting leachate which is not
contained and managed within the site, could seep through the base or
sides of the site or overspill to the surface. Calculating the volume
and predicting the composition of leachate that will be generated can
evaluate the pollution potential.

The different factors that affect leachate composition advance aerobic
or anaerobic conditions that allow different chemical reactions to take
place. Most landfill leachates have high biological oxygen demand,
chemical oxygen demand, ammonia, chloride, sodium, potassium, hardness
and boron levels8. Ammonia is a contaminant, which may be used as an
indicator of contamination, particularly in terms of surface water, as
it can be toxic to fish at low concentrations (1 mg/l)8. Chloride is a
mobile constituent and can also be used as an indicator of
contamination. The leachate from landfills for non-hazardous waste may
produce reducing conditions beneath the landfill, allowing the solution
of iron and manganese from the underlying deposits.

Leachates from landfill sites for non-hazardous waste often contain
complex organic compounds, chlorinated hydrocarbons and metals at
concentrations which pose a threat to ground and surface waters9.
Solvents and other synthetic organic chemicals are significant since
they are hazardous at very low concentrations and are resistant to
degradation. Moreover, they may be transformed in some cases into more
hazardous compounds. Landfills have the potential to produce leachate
for several hundred years.