Priority should be given to the removal of pollution sources in the prioritized
pollution control sites. For the removable pollution sources, it is necessary to
specify the removal method, scope, destination and other contents. For
non-removable pollution sources, the reduction of emission source intensity should
be strengthened, and stricter control requirements should be made on the seepage
control measures and existing time of pollution sources.
5. Risk assessment of groundwater pollution
According to the monitoring data, the annual average PH value of the monitoring well is 6.25, which is faintly acid and reaches Class IV groundwater quality
standard; the ammonia nitrogen content is 0.302 mg/L, reaching Class IV; the total
coliforms are <20–5400 coliforms/L, up to Class IV. In addition, the 13 components are all within the Class I–III groundwater quality standards, among which
volatile phenol, permanganate index and ammonia nitrogen are up to Class III. In
general, the groundwater quality reaches Class V water quality standards.
According to the Guidelines for Health Risk Assessment of Groundwater Pollution,
when the groundwater pollution plumes do not involve the recharge runoff area and
protection area of underground drinking water sources (in-use, standby, emergency
and planned water sources), and the toxic and harmful substances in groundwater
do not exceed Class III standards in the Quality Standard for Ground Water (GB/T
14848-93), Standards for Drinking Water Quality (GB 5749–2006) and other
relevant standards, the health risk assessment of groundwater pollution will not be
started.
(1) Forecasting model
Although strict seepage control measures have been taken in the landfill area, in the
event of broken seepage control layer, the structure leakage of the regulating tank
and leachate treatment station, sewage pipeline leakage, and other emergency
conditions, the leachate will leak into the groundwater environment, which may
cause pollution to the groundwater environment in a certain range in a certain
period of time.
Due to the complex process of migration and transformation of pollutants in
groundwater, there are such functions as adsorption, precipitation, bioabsorption,
chemical and biological degradation. Based on the principle of maximum risk, this
prediction and evaluation does not consider biodegradation such as adsorption and
chemical reaction when simulating pollutant diffusion, but only consider the diffusion process and law of typical pollution due to convection and dispersion.
According to the Technical Guidelines for Environmental Impact
Assessment-Groundwater Environment (HJ 610–2016) and in combination with
this field investigation, the hydrogeological conceptual model of pollutant transport
in the landfill area and downstream groundwater is generalized into a
one-dimensional hydrodynamic dispersion problem of one-dimensional steady
5.4 Southeast China
251
pollution control sites. For the removable pollution sources, it is necessary to
specify the removal method, scope, destination and other contents. For
non-removable pollution sources, the reduction of emission source intensity should
be strengthened, and stricter control requirements should be made on the seepage
control measures and existing time of pollution sources.
5. Risk assessment of groundwater pollution
According to the monitoring data, the annual average PH value of the monitoring well is 6.25, which is faintly acid and reaches Class IV groundwater quality
standard; the ammonia nitrogen content is 0.302 mg/L, reaching Class IV; the total
coliforms are <20–5400 coliforms/L, up to Class IV. In addition, the 13 components are all within the Class I–III groundwater quality standards, among which
volatile phenol, permanganate index and ammonia nitrogen are up to Class III. In
general, the groundwater quality reaches Class V water quality standards.
According to the Guidelines for Health Risk Assessment of Groundwater Pollution,
when the groundwater pollution plumes do not involve the recharge runoff area and
protection area of underground drinking water sources (in-use, standby, emergency
and planned water sources), and the toxic and harmful substances in groundwater
do not exceed Class III standards in the Quality Standard for Ground Water (GB/T
14848-93), Standards for Drinking Water Quality (GB 5749–2006) and other
relevant standards, the health risk assessment of groundwater pollution will not be
started.
(1) Forecasting model
Although strict seepage control measures have been taken in the landfill area, in the
event of broken seepage control layer, the structure leakage of the regulating tank
and leachate treatment station, sewage pipeline leakage, and other emergency
conditions, the leachate will leak into the groundwater environment, which may
cause pollution to the groundwater environment in a certain range in a certain
period of time.
Due to the complex process of migration and transformation of pollutants in
groundwater, there are such functions as adsorption, precipitation, bioabsorption,
chemical and biological degradation. Based on the principle of maximum risk, this
prediction and evaluation does not consider biodegradation such as adsorption and
chemical reaction when simulating pollutant diffusion, but only consider the diffusion process and law of typical pollution due to convection and dispersion.
According to the Technical Guidelines for Environmental Impact
Assessment-Groundwater Environment (HJ 610–2016) and in combination with
this field investigation, the hydrogeological conceptual model of pollutant transport
in the landfill area and downstream groundwater is generalized into a
one-dimensional hydrodynamic dispersion problem of one-dimensional steady
5.4 Southeast China
251