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 0.301 mg/L, reaching class IV. The total coliforms are <20–5400 coliforms/L,
which reaches the Class IV groundwater quality standard. In addition, the 13
components are all within the groundwater quality standards I–III, among which
volatile phenol, permanganate index and nitrates are up to standard III. Generally
speaking, the quality of groundwater meets the Class V sanitary standard of
drinking water.
Taking Class III of groundwater quality standards as the reference standard, it
can be seen from the data in the table that the exceedance rate of pH value is 75%,
with an average value of 6.25; the exceedance rate of ammonia nitrogen is 75%,
and the highest value is 0.638 mg/L; the exceedance rate of volatile phenol is 25%,
the highest value is 0.0021 mg/L, and the average value is 0.0017 mg/L; the
exceedance rate of the total coliforms is 100%, and the highest value reaches 5400
coliforms/L.
The project site is a landfill and is affected by its landform, so the hydraulic
connection between groundwater and surface water is greatly affected by the season. In the wet season, the ground water is recharged by the surface water of a
certain creek and gullies; in the dry season, a certain stream and gullies are
recharged by the groundwater. Since Phase I and II Projects belong to the same
hydrogeological unit and Phase II Project is located upstream of Phase I Project, the
water quality downstream of Phase I Project can be used to analyze the groundwater
quality downstream of the whole site. Individual water quality indexes of M4
monitoring well exceed the standard, indicating that the groundwater downstream
of the landfill is affected by landfill leachate. This may be mainly due to the fact that
Phase I Project was built in the 1990s, when the relevant laws and regulations were
not perfect and the understanding of the seepage control project was not so good
that the seepage control work was incomplete, resulting in leachate affecting the
groundwater. In addition, errors may also occur during sampling or testing.
② Water quality of the monitoring well upstream and downstream of
Landfill Phase II Project
Sampling test results of the monitoring wells upstream and downstream of Phase II
Extension Project (Lipu Testing Company Limited in a province in Southeast
China). See Tables 5.76 and 5.77 for details.
According to Tables 5.76 and 5.77, the upstream and downstream water quality
of the Landfill Phase II Project is within the Class III groundwater quality standard,
and the overall water quality is good.
Comparing the data from the two tables, it can be seen that the total hardness,
total dissolved solids and chloride indexes of the downstream water are about 1.8
times those of the upstream water, the nitrate, nitrite, ammonia-nitrogen and iron
indexes of the downstream water are 2.3 times those of the upstream water, sulfate
and fluoride are 1.5 times and 3.75 times respectively, and the contents of other
heavy metal elements are similar.
5.4 Southeast China
243
and reaches Class IV groundwater quality standard. The ammonia nitrogen content
is 0.301 mg/L, reaching class IV. The total coliforms are <20–5400 coliforms/L,
which reaches the Class IV groundwater quality standard. In addition, the 13
components are all within the groundwater quality standards I–III, among which
volatile phenol, permanganate index and nitrates are up to standard III. Generally
speaking, the quality of groundwater meets the Class V sanitary standard of
drinking water.
Taking Class III of groundwater quality standards as the reference standard, it
can be seen from the data in the table that the exceedance rate of pH value is 75%,
with an average value of 6.25; the exceedance rate of ammonia nitrogen is 75%,
and the highest value is 0.638 mg/L; the exceedance rate of volatile phenol is 25%,
the highest value is 0.0021 mg/L, and the average value is 0.0017 mg/L; the
exceedance rate of the total coliforms is 100%, and the highest value reaches 5400
coliforms/L.
The project site is a landfill and is affected by its landform, so the hydraulic
connection between groundwater and surface water is greatly affected by the season. In the wet season, the ground water is recharged by the surface water of a
certain creek and gullies; in the dry season, a certain stream and gullies are
recharged by the groundwater. Since Phase I and II Projects belong to the same
hydrogeological unit and Phase II Project is located upstream of Phase I Project, the
water quality downstream of Phase I Project can be used to analyze the groundwater
quality downstream of the whole site. Individual water quality indexes of M4
monitoring well exceed the standard, indicating that the groundwater downstream
of the landfill is affected by landfill leachate. This may be mainly due to the fact that
Phase I Project was built in the 1990s, when the relevant laws and regulations were
not perfect and the understanding of the seepage control project was not so good
that the seepage control work was incomplete, resulting in leachate affecting the
groundwater. In addition, errors may also occur during sampling or testing.
② Water quality of the monitoring well upstream and downstream of
Landfill Phase II Project
Sampling test results of the monitoring wells upstream and downstream of Phase II
Extension Project (Lipu Testing Company Limited in a province in Southeast
China). See Tables 5.76 and 5.77 for details.
According to Tables 5.76 and 5.77, the upstream and downstream water quality
of the Landfill Phase II Project is within the Class III groundwater quality standard,
and the overall water quality is good.
Comparing the data from the two tables, it can be seen that the total hardness,
total dissolved solids and chloride indexes of the downstream water are about 1.8
times those of the upstream water, the nitrate, nitrite, ammonia-nitrogen and iron
indexes of the downstream water are 2.3 times those of the upstream water, sulfate
and fluoride are 1.5 times and 3.75 times respectively, and the contents of other
heavy metal elements are similar.
5.4 Southeast China
243