Hydrogy_Dam_deisgn
Budget: ₹1,500 – ₹2,500 INR
Overview ( See Full details, in attached file)
A new coal mine and an associated township are proposed to be built in the area near the Golden River
in Tasmania. Torrensville City Council (the Client) has engaged your firm to provide a conceptual
design for a reservoir system for the proposed mining site and nearby township. The reservoir will be
located in the valley of the Golden River to collect water from the upstream catchment and serve as the
water source for the proposed mine site and the township. You are required to carry out the following
modelling and design tasks.
Task 1. Embarkment Dam (25 marks)
An embankment dam is proposed to be built to manage the water flow from the water storage reservoir
to downstream. Geotechnical site investigations have been conducted. Nine boreholes (BH1~9) were
drilled across the valley with the plane layout as shown in Fig. 1.1. Each borehole is 35 m deep from
the ground soil surface. Core samples were collected from the nine boreholes and tested in a soil
laboratory. As illustrated in Fig. 1.2, five layers of different soils were identified from visual observation
and laboratory tests, which are labelled as L1, L2, L3, L4 and L5. Note that L5 is the bedrock. A lens
of L2 can be observed at BH7, where the extent can be assumed as 2.5 m from the centre of the borehole.
1.2 According to the Client requirement, the seepage through the dam (including through the underlying
soil) must be less than 0.85 m3
/day per metre length of the dam. The Client approved the adoption of
SEEP/W as analysis software in calculating seepage rate. The water depth in the reservoir during wet
season is equal to 10m.
The width of the dam top is 5m and dam shell slope is 2:1. The dam height and the material of the dam
should be determined by you in this conceptual design phase (Fig. 1.4). When determine the overall
height of the dam, an extra 5% of the height should be left to accommodate long term settlement. In
addition, a minimum freeboard should be 0.50 m and an additional 0.25m should be taken into account
if there is potential wave action.
The parameters of material and associated cost of the dam are listed in Table 1.2, which is to assist your
design and assess your design budget.
(1) Please assess the seepage and flow rate through the dam as shown Fig.1.4. In your report, the
flow net contours and seepage velocity contours through the dam should be shown and
maximum seepage velocity should be estimated. Also, provide the evidence of your model
setup of boundary condition and explain the reasons of your definition. (5 marks)
(2) To reduce potential hazard at the flow exit, two preliminary design options by using blanket
drain and toe drain are provided in Fig. 1.5 and Fig. 1.6. Please estimate the seepage rates and
show how the drain design options influence the flow net contours through the dam. Also show
the seepage velocity contours and estimate the maximum seepage velocity. Compare the results
with those of (1) and discuss the functionality of the drain system based on the comparison. (4
marks)
(3) You are required to select one of the drain options that have been discussed in (2). If your
calculated seepage did not meet the requirement, propose your design to reduce seepage. The
properties of core material that can be considered are provided in Table 1.2. For constructability
purpose, only one type of core material is recommended to be used in this design. You are
recommended to find available industry design guidelines and other reliable references to
support your design process. (9 marks)
(4) Compare the shape of phreatic line from all your analysis scenarios and explain what are the
reasons of the difference. Based on your final recommendation in (3), describe the changes of
phreatic line when it goes through different materials and explain this phenomenon by using
the knowledge you learned. (3 marks)
A new coal mine and an associated township are proposed to be built in the area near the Golden River
in Tasmania. Torrensville City Council (the Client) has engaged your firm to provide a conceptual
design for a reservoir system for the proposed mining site and nearby township. The reservoir will be
located in the valley of the Golden River to collect water from the upstream catchment and serve as the
water source for the proposed mine site and the township. You are required to carry out the following
modelling and design tasks.
Task 1. Embarkment Dam (25 marks)
An embankment dam is proposed to be built to manage the water flow from the water storage reservoir
to downstream. Geotechnical site investigations have been conducted. Nine boreholes (BH1~9) were
drilled across the valley with the plane layout as shown in Fig. 1.1. Each borehole is 35 m deep from
the ground soil surface. Core samples were collected from the nine boreholes and tested in a soil
laboratory. As illustrated in Fig. 1.2, five layers of different soils were identified from visual observation
and laboratory tests, which are labelled as L1, L2, L3, L4 and L5. Note that L5 is the bedrock. A lens
of L2 can be observed at BH7, where the extent can be assumed as 2.5 m from the centre of the borehole.
1.2 According to the Client requirement, the seepage through the dam (including through the underlying
soil) must be less than 0.85 m3
/day per metre length of the dam. The Client approved the adoption of
SEEP/W as analysis software in calculating seepage rate. The water depth in the reservoir during wet
season is equal to 10m.
The width of the dam top is 5m and dam shell slope is 2:1. The dam height and the material of the dam
should be determined by you in this conceptual design phase (Fig. 1.4). When determine the overall
height of the dam, an extra 5% of the height should be left to accommodate long term settlement. In
addition, a minimum freeboard should be 0.50 m and an additional 0.25m should be taken into account
if there is potential wave action.
The parameters of material and associated cost of the dam are listed in Table 1.2, which is to assist your
design and assess your design budget.
(1) Please assess the seepage and flow rate through the dam as shown Fig.1.4. In your report, the
flow net contours and seepage velocity contours through the dam should be shown and
maximum seepage velocity should be estimated. Also, provide the evidence of your model
setup of boundary condition and explain the reasons of your definition. (5 marks)
(2) To reduce potential hazard at the flow exit, two preliminary design options by using blanket
drain and toe drain are provided in Fig. 1.5 and Fig. 1.6. Please estimate the seepage rates and
show how the drain design options influence the flow net contours through the dam. Also show
the seepage velocity contours and estimate the maximum seepage velocity. Compare the results
with those of (1) and discuss the functionality of the drain system based on the comparison. (4
marks)
(3) You are required to select one of the drain options that have been discussed in (2). If your
calculated seepage did not meet the requirement, propose your design to reduce seepage. The
properties of core material that can be considered are provided in Table 1.2. For constructability
purpose, only one type of core material is recommended to be used in this design. You are
recommended to find available industry design guidelines and other reliable references to
support your design process. (9 marks)
(4) Compare the shape of phreatic line from all your analysis scenarios and explain what are the
reasons of the difference. Based on your final recommendation in (3), describe the changes of
phreatic line when it goes through different materials and explain this phenomenon by using
the knowledge you learned. (3 marks)