a lowest water level of 2.31 m (January 7, 1994), 1.57 m (February 3, 1981), and
−1.25 m (October 25, 1980); and an average water level of 2.79 m, 2.49 m, and
between 0.18 and 3.47 m respectively.
(2) Overview of geological environment
The ground around the landfill is low and level, with an elevation of 2.4–4.0 m
above sea level and the soil composed of clayey loam and silty soil. A 17 m thick
gley aquiclude exists at the ELE. of −5 to −22 m below the intertidal zone of the
landfill, so that the surface water and landfill percolate are less apt to seep downwards. The shallow groundwater is saline water.
The groundwater in the landfill area is at the level of about 3.0–3.5 m, which
flows from the land to the sea. The surface phreatic water and the first layer of
confined water are saline water, unusable in industrial and agricultural production
or human consumption. The water sources in this area are mainly from the Dazhi
River and deep layers of groundwater.
Multiple aquifers are developed in the Quaternary loose soils of the assessment
area, as shown in Table 5.107, including the phreatic aquifers, micro-confined
aquifer and the first to fifth layers of confined aquifers. The various aquifers have
greatly varied hydrogeological conditions due to difference in ages, hydrodynamic
conditions and genetic types.
The phreatic-micro-confined aquifers are predominant in the landfill, with the
hydrogeological conditions being estuarine-littoral facies deposit. The surface depth
of the phreatic aquifer is generally 5–10 m, and the top depth of the micro-confined
aquifer is 15–22 m, with a thickness ranging between 2 and 15 m. The variation
during a year is correlated to the scale and duration of the atmospheric precipitation
of the corresponding period. The phreatic aquifer is chiefly recharged by the
influent seepage of atmospheric precipitation, and secondly by the infiltration of
farmland irrigation water and lateral recharge of surface water.
About 10 m thick sandy loam layer, 17.3 m thick clay layer and the first confined aquifer are distributed from the surface to −5.6 m, from −5.6 to −22.9 m, and
below −22.9 m respectively. Four layers of aquicludes and confined water are
found alternately from below the first confined aquifer, with the sedimentary layers
about 400 m thick in total. The layers are separated by impermeable beds, without
hydraulic connection.
According to the measurement of Shanghai Bureau of Geology and Mineral
Resources, the soil osmotic coefficient of the Old Port area is that for the sandy
loam soil (from surface to −5.6 m), with a horizontal osmotic coefficient Kh of
2.5 Â 10
−4 cm/s and a vertical osmotic coefficient Kv of 1.9 Â 10
−7 m/s. It can be
inferred that a 17 m clayey aquiclude is distributed from surface −5 to −22 m in the
Old Port Area.
330
5 Application Cases
−1.25 m (October 25, 1980); and an average water level of 2.79 m, 2.49 m, and
between 0.18 and 3.47 m respectively.
(2) Overview of geological environment
The ground around the landfill is low and level, with an elevation of 2.4–4.0 m
above sea level and the soil composed of clayey loam and silty soil. A 17 m thick
gley aquiclude exists at the ELE. of −5 to −22 m below the intertidal zone of the
landfill, so that the surface water and landfill percolate are less apt to seep downwards. The shallow groundwater is saline water.
The groundwater in the landfill area is at the level of about 3.0–3.5 m, which
flows from the land to the sea. The surface phreatic water and the first layer of
confined water are saline water, unusable in industrial and agricultural production
or human consumption. The water sources in this area are mainly from the Dazhi
River and deep layers of groundwater.
Multiple aquifers are developed in the Quaternary loose soils of the assessment
area, as shown in Table 5.107, including the phreatic aquifers, micro-confined
aquifer and the first to fifth layers of confined aquifers. The various aquifers have
greatly varied hydrogeological conditions due to difference in ages, hydrodynamic
conditions and genetic types.
The phreatic-micro-confined aquifers are predominant in the landfill, with the
hydrogeological conditions being estuarine-littoral facies deposit. The surface depth
of the phreatic aquifer is generally 5–10 m, and the top depth of the micro-confined
aquifer is 15–22 m, with a thickness ranging between 2 and 15 m. The variation
during a year is correlated to the scale and duration of the atmospheric precipitation
of the corresponding period. The phreatic aquifer is chiefly recharged by the
influent seepage of atmospheric precipitation, and secondly by the infiltration of
farmland irrigation water and lateral recharge of surface water.
About 10 m thick sandy loam layer, 17.3 m thick clay layer and the first confined aquifer are distributed from the surface to −5.6 m, from −5.6 to −22.9 m, and
below −22.9 m respectively. Four layers of aquicludes and confined water are
found alternately from below the first confined aquifer, with the sedimentary layers
about 400 m thick in total. The layers are separated by impermeable beds, without
hydraulic connection.
According to the measurement of Shanghai Bureau of Geology and Mineral
Resources, the soil osmotic coefficient of the Old Port area is that for the sandy
loam soil (from surface to −5.6 m), with a horizontal osmotic coefficient Kh of
2.5 Â 10
−4 cm/s and a vertical osmotic coefficient Kv of 1.9 Â 10
−7 m/s. It can be
inferred that a 17 m clayey aquiclude is distributed from surface −5 to −22 m in the
Old Port Area.
330
5 Application Cases