(5) Existing monitoring wells of the typical site only monitor the leakage from the
rigid landfill pit, but do not monitor disposal units that may contain toxic and
harmful wastewater, including ① flue gas cleaning wastewater containing
heavy metal pollutants and washing water of the highly toxic waste drum
containing cyanide of the incineration workshop; ② effluent containing heavy
metal pollutants from the physico-chemical workshop; ③ oily wastewater of
the comprehensive utilization workshop; ④ sewage treatment station; ⑤ the
dismantling workshop of waste lead-acid batteries producing electrolyte and ⑥
the oil storage and transportation depot generating waste organic solvents.
(6) The background wells and diffusion wells of the typical site do not take into
account the flow field conditions of the target aquifer. With the help of the
calculation function of numerical simulation software, the collected aquifer
permeability coefficient, porosity and dispersion coefficient are not adopted for
the parameter calibration, but substituted into the numerical model based on the
flow field in June 2015, so as to analyze the capture of the particular pollutant
Pb by the existing groundwater monitoring, and demonstrate and showcase the
effectiveness and rationality of existing monitoring wells. The numerical simulation results indicate that due to the poor permeability and weak dispersity of
the target aquifer of the typical site, the pollution range of the landfill caused by
groundwater immersion is small. Only when the pollution control monitoring
well is close to the point of failure can the characteristic pollutants in the landfill
pit enter the monitoring well under the convection or dispersion of groundwater. If the pollution control monitoring well is far away from the point of
failure, no pollution information can be captured.
(7) According to the requirements of the Draft Guide for the comprehensive disposal site, 16 monitoring wells shall be arranged at the typical site. If the
disposal units that do not produce wastewater and effluent are not considered,
and only monitor the disposal units that produce waste water and effluent
containing toxic and harmful substances, the number of monitoring wells can
be reduced to 10. Furthermore, the existing 6 monitoring wells of the typical
site can be comprehensively utilized. After the final optimization, the typical
site shall have at least 13 monitoring wells, consisting of 6 existing monitoring
wells and 7 monitoring wells to be built. Seven monitoring wells to be built in
the typical site include: ① one pollution control monitoring well in the
lead-acid battery recovery workshop, ② one pollution control monitoring well
in the physico-chemical treatment workshop, ③ one pollution control monitoring well in the incineration workshop, ④ one pollution control monitoring
well in the mineral oil recovery workshop, ⑤ one pollution control monitoring
well in the oil storage and transportation depot, ⑥ one pollution control
monitoring well in the rigid landfill pit and ⑦ one pollution control monitoring
well in the sewage treatment station. One full-field background well and one
full-field diffusion well of the existing six monitoring wells at the site shall be
used as upstream background monitoring wells, one landfill background well at
the northern end of the rigid landfill pit and two pollution monitoring wells at
the southern end shall be used as pollution control monitoring wells of the rigid
328
5 Application Cases
rigid landfill pit, but do not monitor disposal units that may contain toxic and
harmful wastewater, including ① flue gas cleaning wastewater containing
heavy metal pollutants and washing water of the highly toxic waste drum
containing cyanide of the incineration workshop; ② effluent containing heavy
metal pollutants from the physico-chemical workshop; ③ oily wastewater of
the comprehensive utilization workshop; ④ sewage treatment station; ⑤ the
dismantling workshop of waste lead-acid batteries producing electrolyte and ⑥
the oil storage and transportation depot generating waste organic solvents.
(6) The background wells and diffusion wells of the typical site do not take into
account the flow field conditions of the target aquifer. With the help of the
calculation function of numerical simulation software, the collected aquifer
permeability coefficient, porosity and dispersion coefficient are not adopted for
the parameter calibration, but substituted into the numerical model based on the
flow field in June 2015, so as to analyze the capture of the particular pollutant
Pb by the existing groundwater monitoring, and demonstrate and showcase the
effectiveness and rationality of existing monitoring wells. The numerical simulation results indicate that due to the poor permeability and weak dispersity of
the target aquifer of the typical site, the pollution range of the landfill caused by
groundwater immersion is small. Only when the pollution control monitoring
well is close to the point of failure can the characteristic pollutants in the landfill
pit enter the monitoring well under the convection or dispersion of groundwater. If the pollution control monitoring well is far away from the point of
failure, no pollution information can be captured.
(7) According to the requirements of the Draft Guide for the comprehensive disposal site, 16 monitoring wells shall be arranged at the typical site. If the
disposal units that do not produce wastewater and effluent are not considered,
and only monitor the disposal units that produce waste water and effluent
containing toxic and harmful substances, the number of monitoring wells can
be reduced to 10. Furthermore, the existing 6 monitoring wells of the typical
site can be comprehensively utilized. After the final optimization, the typical
site shall have at least 13 monitoring wells, consisting of 6 existing monitoring
wells and 7 monitoring wells to be built. Seven monitoring wells to be built in
the typical site include: ① one pollution control monitoring well in the
lead-acid battery recovery workshop, ② one pollution control monitoring well
in the physico-chemical treatment workshop, ③ one pollution control monitoring well in the incineration workshop, ④ one pollution control monitoring
well in the mineral oil recovery workshop, ⑤ one pollution control monitoring
well in the oil storage and transportation depot, ⑥ one pollution control
monitoring well in the rigid landfill pit and ⑦ one pollution control monitoring
well in the sewage treatment station. One full-field background well and one
full-field diffusion well of the existing six monitoring wells at the site shall be
used as upstream background monitoring wells, one landfill background well at
the northern end of the rigid landfill pit and two pollution monitoring wells at
the southern end shall be used as pollution control monitoring wells of the rigid
328
5 Application Cases