final report1111 - undp
TRANSCRIPT
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NOV. 2016
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Content
Chapter 1 General Information .................................................................................. 1
1.1 Overview .............................................................................................................. 1
1.2 Hydrology ............................................................................................................. 1 1.2.1 Climate ........................................................................................................... 1 1.2.2 Hydrology ...................................................................................................... 2
1.3 Engineering Geology ............................................................................................ 2 1.3.1 Landform........................................................................................................ 2 1.3.2 Strata lithology ............................................................................................... 3 1.3.3 Natural building materials .............................................................................. 3
1.4 Engineering Tasks and Scale ................................................................................ 3 1.4.1 Necessity and advantage ................................................................................ 3 1.4.2 Project scale ................................................................................................... 4
1.5 Project Layout and Main Buildings ...................................................................... 4 1.5.1 Engineering scale and building level ............................................................. 4 1.5.2 General project layout .................................................................................... 5 1.5.3 Main buildings ............................................................................................... 5
1.6 Electromechanical and Metallic Structure ........................................................... 6 1.6.1 Hydraulic machinery ...................................................................................... 6 1.6.2 Electrical connecting system method ............................................................. 6 1.6.3 Main equipment selection .............................................................................. 6 1.6.4 Metal structure ............................................................................................... 7
1.7 Project Management ............................................................................................. 7
1.8 Construction Management Plan ........................................................................... 7
1.9 Labor Safety and Industrial Sanitation ................................................................. 8
1.10 Submerge and Land Requisition ........................................................................ 8
1.11 Water and Soil Conservation .............................................................................. 9
1.12 Environmental Impact Assessment .................................................................. 10
1.13 Project Cost Estimates ...................................................................................... 10 1.13.1 Compilation basis....................................................................................... 10 1.13.2 Unit price ................................................................................................... 11 1.13.3 Total project investment ............................................................................. 11
1.14 Economic Evaluation ....................................................................................... 11
1.15 Conclusions and Suggestions for Future Work ................................................ 11 1.15.1 Conclusions ................................................................................................ 11 1.15.2 Suggestions for future ................................................................................ 12
Chapter 2 Hydrology ................................................................................................. 16
2.1 Overview of the Drainage Basin ........................................................................ 16
2.2 Climate ............................................................................................................... 16
2.3 Basic Hydrological Data .................................................................................... 17 2.3.1 Hydrological station network and information ............................................ 17 2.3.2 Application of the data ................................................................................. 18
2.4 Runoff ................................................................................................................. 19
2.5 Flood ................................................................................................................... 19
2.6 Water-level Discharge Relation Curve at the Dam and Plant Site ..................... 19
2.7 Sediment ............................................................................................................. 21
2.8 Attached Figures ................................................................................................. 22
Chapter 3 Engineering Geology ............................................................................... 25
3.1 Overview ............................................................................................................ 25
3.2 Regional Geology ............................................................................................... 25 3.2.1 Landform...................................................................................................... 25 3.2.2 Strata lithology ............................................................................................. 25 3.2.3 Geological structure ..................................................................................... 26 3.2.4 Hydrological geology................................................................................... 26
3.3 Natural Building Materials ................................................................................. 26
3.4 Conclusions and Suggestions ............................................................................. 26
Chapter 4 Engineering Tasks and Scale ................................................................... 28
4.1 General Situation ................................................................................................ 28 4.1.1 Physical geography ...................................................................................... 28 4.1.2 Social and economic situation ..................................................................... 28 4.1.3 Hydropower resources and the development and utilization situation ........ 29 4.1.4 Necessity of the project ................................................................................ 29
4.2 Scale of Power Generation Projects ................................................................... 30 4.2.1 Power supply range and load forecast ......................................................... 30 4.2.2 Drafting of the scheme ................................................................................. 30 4.2.3 Calculation of hydropower and installed capacity selection ........................ 31
Chapter 5 Project layout and main buildings ......................................................... 35
5.1 Design basis ........................................................................................................ 35 5.1.1 Main technical specifications and references .............................................. 35 5.1.2 Basic design information ............................................................................. 35 5.1.3 Project grade and standards ......................................................................... 36
5.2 Project location and general layout .................................................................... 36
5.2.1 Location of the dam ..................................................................................... 36 5.2.2 Location of the power house ........................................................................ 38 5.2.3 Selection of water diversion method ............................................................ 40 5.2.4 General layout of the project ........................................................................ 41
5.3 Water retaining structures ................................................................................... 41 5.3.1 Layout of the dam ........................................................................................ 41 5.3.2 Stability calculation ..................................................................................... 42 5.3.3 Flood discharge and energy dissipation facilities ........................................ 43
5.4 Open canal diversion method (comparative plan) .............................................. 43 5.4.1 Open canal ................................................................................................... 43 5.4.2 Pressure forebay ........................................................................................... 44
5.5 Penstock (recommended plan) ........................................................................... 45
5.6 Power house and booster station ........................................................................ 46 5.6.1 Selection of the power house location ......................................................... 46 5.6.2 Power house structure .................................................................................. 46 5.6.3 Booster station ............................................................................................. 46 5.6.4 Housing for the use of administration .......................................................... 47 5.6.5 Entrance road ............................................................................................... 47
Chapter 6 Electromechanical and metal structures ............................................... 48
6.1 Units ................................................................................................................... 48
6.2 Access mode to power system and main electrical connection .......................... 50 6.2.1 Access mode to power system ..................................................................... 50 6.2.2 Main connection........................................................................................... 50
6.3 Selection of main electromechanical equipment ................................................ 52 6.3.1 Short circuit current ..................................................................................... 52 6.3.2 Selection of the main electrical equipment .................................................. 52
6.4 Layout of the electromechanical equipment ...................................................... 54 6.4.1 Inner-plant electrical equipment layout ....................................................... 54 6.4.2 Layout of the booster station ........................................................................ 54
6.5 Metallic structure ................................................................................................ 55 6.5.1 Dam and metallic structures at the water intake .......................................... 55 6.5.2 Metallic structure for tailwater ..................................................................... 56 6.5.3 Penstocks...................................................................................................... 56 6.5.4 Main quantities of metallic structures and equipment ................................. 56
6.6 Heating ventilation and fire protection ............................................................... 56 6.6.1 Heating ventilation ....................................................................................... 56 6.6.2 Fire protection .............................................................................................. 57
6.7 Lightning protection and earthing ...................................................................... 60
Chapter7 Project Management ................................................................................ 61
7.1 Introduction ........................................................................................................ 61
7.2 Operation management ....................................................................................... 62 7.2.1 Project dispatching operation ....................................................................... 62 7.2.2 Management and maintenance of the structures .......................................... 62 7.2.3Management and maintenance of metallic structures ................................... 62
7.3 Scope of project management and protection .................................................... 63 7.3.1 Project management scope ........................................................................... 63 7.3.2 Protection scope ........................................................................................... 63
7.4 Project management facilities and maintenance of the equipment .................... 64 7.4.1 Project management facilities ...................................................................... 64 7.4.2 Maintenance of the equipment ..................................................................... 64
Chapter 8 Construction organization planning ...................................................... 66
8.1 Project profile ..................................................................................................... 66
8.2 Construction diversion ....................................................................................... 67 8.2.1 Diversion standards ...................................................................................... 67 8.2.2 Diversion method ......................................................................................... 68
8.3 Selection of the material site and the excavation ............................................... 68 8.3.1 Selection of the material site ........................................................................ 68
8.4 Construction of the project’s main works ........................................................... 68
8.5 Construction of the diversion system ................................................................. 69
8.6 Construction of the power house ........................................................................ 70
8.7 Transportation for construction .......................................................................... 71 8.7.1 Selection of transportation means ................................................................ 71 8.7.2 Outbound transportation .............................................................................. 71 8.7.3 Internal transportation .................................................................................. 71
8.8 General layout of the construction ..................................................................... 72 8.8.1 The planning and layout principle of the construction ................................ 72 8.8.2 Construction zoning and layout planning .................................................... 72 8.8.3 Waste slags site ............................................................................................ 73
8.9 General construction progress ............................................................................ 74 8.9.1 Implementation basis and principle ............................................................. 74 8.9.2 General construction progress...................................................................... 74
8.10 Main construction machinery ........................................................................... 74
Chapter 9 Labor Safety and Industrial Sanitation ................................................. 76
9.1 Design Basis ....................................................................................................... 76 9.1.1 Provisions of the national and local administration ..................................... 76 9.1.2 Technical specifications, procedures and standards ..................................... 76
9.2 Project Overview ................................................................................................ 76 9.2.1 Project location ............................................................................................ 76 9.2.2 Project layout ............................................................................................... 76 9.2.3 Characteristics of natural conditions ............................................................ 77 9.2.4 Project benefit and major hazards ................................................................ 77
9.3 General Layout of the Project ............................................................................ 77
9.4 Labor Safety ....................................................................................................... 79 9.4.1 Prevention of Fire and Explosion ................................................................ 79 9.4.2 Electrical damage prevention ....................................................................... 79 9.4.3 Mechanical damage prevention and crash damage prevention .................... 80 9.4.4 Flood prevention and drowning prevention ................................................. 80
9.5 Industrial Sanitation ........................................................................................... 80 9.5.1 Noise proof and vibration proof ................................................................... 81 9.5.2 Temperature and humidity control ............................................................... 81 9.5.3 Lighting and illumination ............................................................................ 82 9.5.4 Dust proof, antifouling, anti-corrosion and antitoxin .................................. 82 9.5.5 Anti electromagnetic radiation ..................................................................... 82
9.6 Safety and Health Facilities ................................................................................ 82
9.7 Safety Precautions .............................................................................................. 83 9.7.1 Labor safety precautions .............................................................................. 83 9.7.2 Emergency measures ................................................................................... 83
Chapter 10 Inundation Treatment and Land Requisition ..................................... 85
10.1 Overview .......................................................................................................... 85
10.2 Design Basis ..................................................................................................... 85 10.2.1 Laws and Regulations, Specifications and Codes ...................................... 85 10.2.2 Design data................................................................................................. 86
10.3 Inundation Treatment ....................................................................................... 86
10.4 Land Requisition of the Project ........................................................................ 86
Chapter 11 Water and Soil Conservation ................................................................ 87
11.1 Principles and Standards ................................................................................... 87
11.2 Project and Overview of Project Area .............................................................. 87 11.2.1 Overview .................................................................................................... 87 11.2.2 Status and Prevention of soil erosion ......................................................... 88
11.3 Forecast of Water and Soil Erosion .................................................................. 88 11.3.1 Forecasting Basis ....................................................................................... 88 11.3.2 Forecasting Time Period ............................................................................ 88 11.3.3 Content and Method of Forecast ................................................................ 89 11.3.4 Forecast results and comprehensive analysis ............................................. 89
Feasibility report of Chipota falls hydropower station
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Chapter 1 General Information
1.1 Overview
The China - Zambia Renewable Energy Technology Transfer Project carried out
jointly through cooperation by UNDP, Zambia Ministry of Mine Energy and Water
Resources and Ministry of Science and Technology of the People’s Republic of China,
is focusing on the rural electrification in Zambia. By way of capacity building and
demonstration projects, this project will absorb and utilize the Chinese experience to
promote social and economic development in Africa. The project term is 4 years.
CHIPOTA FALLS hydropower station (hereinafter referred to as CHIPOTA
hydropower station) is located on the MULEMBO River, CHELA TAMBULE village,
SERENJE region of the Central Province of Zambia, 400 km away from Lusaka, the
capital. The geographical location of the site is latitude 13°13' 4.8" S, and longitude
30°25' 52.24" E. The river is the third-order tributary of Zambezi River (first-order
tributary is the Luangwa River, and the second-order tributary is Lukasashi River).
The river originates from the Muchinga Mountains, and the source is at an elevation
of 1615m. Above the dam site, the length of the river is about 25.8km, the average
gradient ratio is about 6‰, and the catchment area is about 140km2.
The installed capacity of the project is 2 x 100kW, with a design head of 45.38m,
and a design flow of 0.68m3/s. The average annual power generation capacity is
1.3553 million kWh, with annual installed utilization hours of 6777 hours. The main
works consist of the dam, penstock, power house, tailrace and booster station.
Through the site survey, data collection and sorting in June 2016, a Feasibility
Study Report of CHIPOTA FALLS Hydropower Station was completed in late August
of 2016.
1.2 Hydrology
1.2.1 Climate The Central Province of Zambia has a mild tropical savanna climate, abundant
rainfall, and an average annual temperature of 21℃. It has three seasons throughout
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the year: from May to August, it is the dry, cool season, with the temperature between
15 ~ 27℃, a harvest season for most crops; from September to November, it is the dry,
hot season, with the temperature between 26 ~ 36℃; from December to the next April,
it is the warm, wet season, with the temperature slightly lower than the dry cool
season, and the annual rainfall concentrated in this season. According to the
meteorological data of the Hong Kong Observatory (1961~1991 year), the average
annual rainfall is 1133.6mm.
1.2.2 Hydrology There are no rain-gauge and hydrological stations near the site and rivers
surrounding the site. Thus, it lacks hydrological data.
Runoff
The CHIPOTA hydropower station has a catchment area of 140km2. Since there
is no measured hydrological data at the dam site, the runoff is calculated by
combining the field measurement with the distribution regularities of the average
monthly discharge at Shiwang’andu gauging station, which is located in Northern
Province; thus, the average monthly flow at this site will be determined using the
same process. The results obtained will be re-measured and the imputed results will
correspond to the fact. After calculation, the average annual flow at the dam site of
CHIPOTA hydropower station is 0.68m3/s, for P=25%, P=50%, P=75%. The three
design average monthly flows are respectively 1.14m3/s, 0.68m3/s and 0.4m3/s.
Flood
Since there is no measured flood data at the dam site, it is proposed to adopt the
reverse estimation of the historical flood line to work out the flood discharge, which is
figured out to be 110m3/s.
1.3 Engineering Geology
1.3.1 Landform The site is located in a platform fracture zone. Through long-term erosion of the
river, the platform broke into sections lengthwise along the river and formed
multiple-cascade waterfalls. On the left bank of the river is a dense forest and steep
mountains, and on the left of the ridge is another small tributary. On the right side of
the river are relatively flat mountains. At the elevation position where the
final-cascade waterfall is visible is a relatively flat and open sloping field, where the
Feasibility report of Chipota falls hydropower station
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trees are flourishing but relatively sparse. A traffic road is located on the right side of
the river. Above the visible first-cascade waterfall is flat grassland, which is not
eligible for storage capacity.
1.3.2 Strata lithology The site selection is conducted without carrying out a geological survey, but
with only the general field visit. Above the dam site no adverse geological structure is
found. Portions of rocks in the section of riverbed are exposed. On the left and right
bank is flat grassland where the covering layer is not thick; thus, the excavation of
dam foundation works is relatively simple.
Below the dam site, the riverbed ladders are fault scarps, forming cascade
waterfalls. The fault scarps have no signs of further development towards the
upstream. The rock is dark red, and should be karst-rock, a kind of basalt. It is hard.
The area for the plant is a gentle sloping field with exposed rock. The rock
property is same as that of the riverbed.
1.3.3 Natural building materials The adjacent area of the site is the basalt area, the stone of which is suitable for
water conservancy engineering. In the valley near the site, there is silver sand,
however, which is of high silt content and is only suitable to be used as mortar, but
not structural parts. The timber is mainly weed trees, which can be used as auxiliary
material of scaffolding, while the building materials need to be purchased.
1.4 Engineering Tasks and Scale
1.4.1 Necessity and advantage The area is rich in mineral resources, forests and water resources, but the
development level is not high. The local people mainly live on crop farming. The
social and economic conditions in the region are still at a moderate level in Zambia.
The population near the site is about 15,000. It is where the headman
KABAMBA resides, where there are communities, a primary school, junior high
school (high school to be built), hospital and local court. It is understood that the
residents here basically have no access to electricity for lighting and other living
conveniences; and only a few residents get lighting electricity through household
solar energy devices. It is very necessary to build a power station to supply electricity
for lighting and the processing of agricultural products.
Feasibility report of Chipota falls hydropower station
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Additionally, the development of CHIPOTA hydropower station can enhance
the development of mineral and tourism resources, to promote local economic
development rapidly and stably. At the same time, the project will improve the
electrification, while reducing the consumption of biological fuel and improving the
ecological environment. Therefore, the construction of CHIPOTA hydropower station
is critical.
1.4.2 Project scale The proposal of installed capacity is based on the requirements of recent
household and production use and a 5~10 year projection to ensure that the waterfall
landscape does not change greatly. According to calculations, the recent maximum
household electricity load is 120kW, the guaranteed output power of the site is
154.72kW (P=75%), and the average output power is 246.87kW. Therefore, it is
relatively reasonable to choose the installed capacity of 2×100kW. The index of the
hydropower station is in Table 1-1.
Table 1-1 Calculation Results of Hydropower Index
Item Index
CHIPOTA Hydropower Station:
Design head(m) 45.38
Guaranteed discharge(m³/s) 0.40
Guaranteed output(kW) 154.72
Installed capacity(kW) 2×100
Average annual generation(kWh) 1355,300
Annual utilization hours(h) 6777
1.5 Project Layout and Main Buildings
1.5.1 Engineering scale and building level CHIPOTA hydropower station is a hydropower project mainly for power
generation, with a maximum dam height of 3.5m and an installed capacity of
2×100kW. According to the Design Code for Small Hydropower Station
(GB50071-2002) in China, this project is categorized as level V, whose main
Feasibility report of Chipota falls hydropower station
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buildings, i.e., the dams, powerhouses and penstocks and other temporary buildings,
are categorized as level V. Each building level and the corresponding flood standards
are listed in Table 1-2:
Table 1-2 Building Level and Flood Standards
Building Level Flood Standards(Return Period)
Design Calibrated
Dams 5 10 20
Powerhouses 5 20 50
Penstocks 5 10 20
Other temporary buildings 5 5 Note: Due to the lack of flood data, the actual calibrated flood is estimated to be
110m3/s (Chapter Hydrology).
1.5.2 General project layout The power station project consists of a dam, penstock, powerhouse, tailrace and
booster station. The dam is arranged in an appropriate position in the upper reaches of
the first-cascade waterfall. The penstocks are laid along the right bank of the river.
The powerhouse is arranged on the gentle slope on the right bank, where the bottom
of the fourth-cascade waterfall is. The booster station is arranged by the upstream side
close to the powerhouse.
1.5.3 Main buildings The dam type is a rubble concrete gravity dam. The crest elevation is 1421.50m,
0.73m below the deck elevation of the upstream bridge. The minimum foundation
plane elevation is 1418 m. The maximum dam height is 3.5m. The length of the dam
axis is 30m. The crest width is 1.50m, and the maximum dam bottom width is 4.00m.
The upstream face is vertical, and the downstream dam slope is 1:0.7. The overflow
face uses WES curve and underflow energy dissipation is adopted.
The power generation water diversion system is arranged on the right bank of
the dam, including the water inlet and penstocks. The design flow is 0.68m3/s. The
water diversion pipelines use a steel pipe structure.
Powerhouse: The power station is the ground powerhouse and adopts a masonry
structure type and a light roof, with a length of 12m, width of 6.8m, height of 4.5m,
and powerhouse ground elevation of 1371.50m. Two sets of stand-alone 100kW
Feasibility report of Chipota falls hydropower station
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Turgo turbine generator units are installed in the powerhouse, with a total installed
capacity of 200kW. The turbine model is XJA-W-46/1×11, and the spacing between
units is 5m.
The booster station is arranged on the upstream side of the powerhouse. The
plane size is 5×5m (length×width), and the ground elevation is 1371.5m. The main
transformer is arranged in the booster station by the side upstream from the
powerhouse.
1.6 Electromechanical and Metallic Structure
1.6.1 Hydraulic machinery After a comparison and selection of installed capacity, the power station is
installed with 2 sets of Turgo turbine generator units with a stand-alone capacity of
100kW and a total installed capacity of 200kW.
The design head of the power station is 45.38m. Through comprehensive
economical comparison, the model of the selected water turbine is XJA-W-46/1×11.
Its rated head is 46m, rated speed is 600r/min, and rated flow is 0.34m3/s.
The model of the generator is SFW100-10/740, with a rated capacity of 100kW,
and a rated voltage of 0.4kV.
Main auxiliary equipment: The model of the speed governor is CJWT-1.
1.6.2 Electrical connecting system method Residents in the vicinity of the power station basically have no access to
electricity for lighting and other living conveniences. It is understood that very few
residents get electricity for lighting through household solar energy devices. This
power station will solve the electricity utilization of 15,000 people in the vicinity.
There is no power grid nearby, thus, the station will operate off the grid. The total
installed capacity of the power station is 2×100kW, and the annual power generation
capacity is 1.3553 million kWh. It is 10km from the power station to the power
supply area, and the power is delivered to the community via 11kV lines and then
stepped down to 400V/200V to the users.
1.6.3 Main equipment selection The triad NDK-2001 low voltage unit intelligent control panels have been
selected as the generator voltage side controller and power distribution unit. Each is
inbuilt with a ME-630A type air circuit breaker. A ZR-VV22-95mm2 type flame
Feasibility report of Chipota falls hydropower station
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retardant PVC insulated cable has been selected as the generator terminal lead,
running with one line per phase.
The 11kV line side switch equipment is of outdoor type. A ZW8-12/630 type
vacuum circuit breaker and isolation switch GW9-12/630 is adopted.
In order to support the generator capacity, the main transformer has adopted a
three-phase oil immersed natural cooling copper core double winding transformer,
which is designed according to the main wiring. The model number is S11-250, 11 ±
5%/0.4kV, and the capacity is 250kVA.
1.6.4 Metal structure The power station is a diversion type hydropower station mainly for power
generation. The metal structured equipment includes one metallic gate (including the
supporting hoist), one φ300 flushing gate valve, one trash rack, a 69t penstock with
accessories, and 6 expansion joints. The distance between the dam and the
powerhouse is short, and the gate hoisting equipment is small in size and of low
operating frequency. If adopting an electric device to control the hoist, the cost will be
high and the maintenance difficult, so we chose to adopt a manual device for it.
The length of the main pipe of the penstock is 530m with a diameter of 650mm,
and wall thickness of 6 ~ 8mm.
1.7 Project Management
CHIPOTA hydro power station is located on the MULEMBO River where
headman KABAMBA lived, in CHELA TAMBULE village, SERENJE area, Central
Province, Zambia. This is a hydropower station mainly for hydropower generation
with an installed capacity of 200kW. During the construction period, a construction
project department shall be established to perform the function of administration; after
the project is built, it will be transferred to the owner who will perform the permanent
operation and administration functions of the project.
1.8 Construction Management Plan
The whole project is arranged on the right bank, where the slope along the river
bank is gentle, and there is more available construction space. Therefore, it is
considered to make use of the existing terrain conditions for production and living
Feasibility report of Chipota falls hydropower station
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during the construction period. The general construction planning principles are: take
construction needs of the main works as the center; make an overall plan; make a
compact layout; fall fewer trees; and make it easy for management. The layout of all
of the construction facilities should: meet the needs of the construction process and be
consistent with the relevant local safety, fire prevention, health and environmental
regulations, etc.
1.9 Labor Safety and Industrial Sanitation
Labor safety includes fire prevention, explosion-proofing, electrical damage
prevention, mechanical vibration hazards prevention and noise dampening. In
addition to making fire protection engineering facilities in the powerhouse, it also
needs to strengthen the fire prevention education. Open flame is strictly prohibited in
the powerhouse. Pressure vessels are all equipped with pressure relief devices, so all
personnel need to take strict precautions against explosion. It is required to regularly
check all of the electrical equipment and the electrician-used safety tools. In the initial
power generation scheme, the electrical part of the power distribution unit, which may
come in contact by the operating personnel, shall be installed with protective railings
and safety signs.
In terms of the structures like the working platform, pedestrian channel, the
various holes, pits and gate slots, water collection wells, hanging hole, shaft and so on,
the fall height of which is more than 2.0m, a 1.2m high fixed protective railing needs
to be installed. A check valve shall be installed on the water pump drainage pipeline
of the mechanical drainage system to prevent water intrusion.
Noise reduction should be made by reasonably arranging the noise sources.
Arrange the main noise sources, such as the main transformer station and switch
station, in the location of the duty room which is far away from the power house. The
partition wall shall be arranged between the duty rooms to reduce the chance of
hearing loss to the operator on duty.
1.10 Submerge and Land Requisition
The dam of the CHIPOTA hydropower station is very low. Below the normal
water level is the natural river course where there is no farmland or submerged houses;
Feasibility report of Chipota falls hydropower station
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thus, there is no submerge loss. According to the geological survey results at the dam
site, both sides of the dam have good stability, and no bank landslide will be caused
after the dam is completed.
According to the junction layout and construction organization design of the
power station, the permanent project land occupied by the CHIPOTA hydropower
station is about 4500m2, which is mainly used for the powerhouse, booster station,
water diversion and power generation system. Temporarily occupied land for the
project construction use is 2000m2, which will be mainly temporarily occupied by a
slag disposal pit and construction enterprises.
1.11 Water and Soil Conservation
The possible newly increased water and soil loss area due to this project mainly
includes the excavation surface area in the main works area, living quarters,
permanent road excavation surface area, material field excavation and stripping area,
slag disposal pit surface area, and temporarily occupied land area, equaling a total of
6500m2.
Prevention and control measures: the prevention and control of the newly
increased water and soil loss area in the project construction area should be led by
engineering measures, such as building flood control and slag blocking structures in
the slag disposal pit; building a slag ridge and drainage around the material field and
construction working face; building drainage ditches on both sides of the construction
road; making use of the control and fast-acting property of the engineering measures
to ensure the recent construction waste slag and solid waste is not out of the ditch and
will not be dumped into the river.
Investment budget estimate: the water and soil conservation project of the
CHIPOTA hydropower station is a supporting project of the main works. The project
mainly includes the soil and stone material field, the abandoned material field, the
temporary construction land and the water and soil conservation design and control.
The remediation content is slag blocking, sod revetment, drainage and greening. The
total investment of the water and soil conservation is 10,600 USD.
Feasibility�report�of�Chipota�falls�hydropower�station�
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1.12 Environmental Impact Assessment
The CHIPOTA hydropower station does not produce waste water, waste gas or
waste residue. The beneficial effects come forth after the implementation of the
construction, and it will be great and lasing for a long period. While the negative
effects may come forth mainly in the implementation process of the construction, it
will be small and lasting only a short period. The requisition of the land is irreversible,
but the other negative effects can all be reduced by adopting certain measures, and
there will be no limiting factors restricting the launch of the project.
The waste water in the construction will be discharged into the river after
treatment in the primary treatment pool, which will be set near the aggregate flushing
field and construction area of the gate and dam project. The waste oil produced by
mechanical maintenance will be treated by building a horizontal-flow type oil-water
separation tank. The sanitary sewage will be treated by a septic tank. Transport
vehicles must be installed with an exhaust buffer to ensure standard vehicle exhaust
emissions requirements. At the same time, the control of construction mechanical
noise will be managed. Supervision and management will set up a specialized
environmental protection management institution to monitor sanitary conditions,
water quality and noise.
The increased investment for the project environmental protection is 8,800
USD.
1.13 Project Cost Estimates
1.13.1 Compilation basis 1) The construction shall be implemented on the basis of the Budget Estimate
Quota of Water Conservancy Construction Project issued by the Ministry of Water
Resources, the People’s Republic of China in 2002
2) The installation project shall implement the Budget Estimate Quota of Water
Conservancy and Hydropower Equipment Installation Project issued by MWR of the
People’s Republic of China in 2002
3) The construction machinery time and cost shall be implemented on the basis
of the Time Cost Quota of Water Conservancy and Hydropower Project Construction
Machinery issued by the Ministry of Water Resources of the People’s Republic of
Feasibility report of Chipota falls hydropower station
12
3) Comprehensive assessment of the investigation and study: there are no
environmental factors limiting the construction of the project. From the perspective of
environmental protection, the project is feasible.
The project has a superior geographical location and significant social benefit. It
is technically feasible with good conditions for the construction. It will play a positive
role in promoting sustainable and stable economic development in the region.
1.15.2 Suggestions for future 1) To investigate the hydrogeological information of the project site, providing
reliable basis for hydrological calculation.
2) To optimize the design of various hydraulic structures.
Feasibility report of Chipota falls hydropower station
13
Table 1-3 Engineering Characteristic Table
S. No. Name of index Unit Parameter Remark
I Hydrology MULEMBO
River
1 Catchment area km2 140
2 Average annual rainfall mm 1133.6
3 Average discharge m3/s 0.68
II Characteristic water level
(I) Powerhouse
1 Submerged water level m 1369.50
III Water diversion system
(I) Dam
1 Dam axis length m 30
2 Dam height m 3.5
3 Crest elevation m 1421.50
4 Crest width m 1.5
5 Bottom width m 4.0
(II) Penstock Outdoor steel tube
1 Main pipe length m 530
2 Main pipe inner diameter mm 650
3 Fork tube diameter mm 400
4 Wall thickness mm 6-8
5 Design total discharge m3/s 0.68
(III) Powerhouse
1 Ground elevation m 1371.50
2 size (L * W* H) m 12×6.8×4.0
3 Mounting elevation of turbine m
1372.08
Feasibility report of Chipota falls hydropower station
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Chapter 2 Hydrology
2.1 Overview of the Drainage Basin
The CHIPOTA hydropower station is located on the MULEMBO River (where
the headman KABAMBA is located), CHELA TAMBULE village, SERENJE region
of the Central Province of Zambia. The river is the third-order tributary of Zambezi
River (first-order tributary is the Luangwa River, and the second-order tributary is
Lukasashi River). The river originates from the Muchinga Mountains, and the source
is at an elevation of 1615m. The length of the river above the dam site is about
25.8km and the average gradient ratio is about 6‰. The catchment area is about
140km2.
2.2 Climate
The central province of Zambia has a mild tropical savanna climate with
abundant rainfall, and an average annual temperature of 21℃. It has three seasons
throughout the year: from May to August, it is the dry cool season, with the
temperature between 15 ~ 27℃, a harvest season for most crops; from September to
November, it is the dry, hot season, with the temperature between 26 ~ 36℃; from
December to April, it is the warm, wet season, which has a relatively lower
temperature than the dry cool season and the annual rainfall concentrated in this
season. According to the meteorological data of the Hong Kong Observatory
(1961~1991 year), the average annual rainfall is 1133.6mm. The rainfall data is in
Table 2-1 below.
Table 2-1 SERENJE Rainfall Records
Climate data Year January February March April May June Total
Rainfall (mm) 1961-1991 279.4 251.6 155.8 42.6 5.3 10.3
Climate data Year July August Septem Octobe Novemb Decembe 1133.6
Feasibility report of Chipota falls hydropower station
17
ber r er r
Rainfall (mm) 1961-1991 0.3 0.3 0.6 15 110.9 261.5
Note: The geological coordinates of the weather station: latitude 13.2°S,
longitude 30.2°E, cited from the Hong Kong Observatory
2.3 Basic Hydrological Data
2.3.1 Hydrological station network and information There are no rain-gauge stations or hydrological stations near the site and rivers
surrounding the site. Thus, it lacks hydrological data.
According to the Site Selection Report of Chipota Falls, Chilambwe Falls and
Nyinaluzi Sites prepared by the International Center on Small Hydro Power, in order
to identify the data of the section runoff, the engineers concluded the value to be 1.3
m3/s through field measurement and identified this value as the monthly average in
April. They used the distribution regularities of the average monthly flow at
Shiwang’andu gauging station located in the northern province to work out the
average monthly flow of the whole year. Based on the average monthly flow series,
they were able to calculate the average monthly flow duration curve of the CHIPOTA
FALLS hydropower station site.
Table 2-2 Annual Flow Conversion Table of Average Monthly flow at CHIPOTA
FALLS SITE
Month 1 2 3 4 5 6 7 8 9 10 11 12
Shiwang’andu
average monthly
flow
12.9 15.5 18.4 15.4 10.9 8.4 7.1 5.5 4.2 3.2 3.2 7.5
Convert coefficient
1.3/15.4≈0.0844
CFS average monthly discharge
1.08 1.30 1.55 1.30 0.92 0.71 0.60 0.46 0.35 0.27 0.27 0.63
F
2.3.
the
mea
whi
that
mea
feas
freq
Figu
Figure 2-1 A
2 ApplicatiAfter acq
site, in ord
asurement s
ich is very
t the averag
asurement v
sibility study
They ra
quency and
ure 2-2 Ave
Feas
Average mo
on of the daquiring the
der to veri
survey of th
close to the
ge monthly
value in A
y will adop
anked the "G
draw the fre
erage month
sibility report of
onthly flow
ata above men
fy the relia
he flow in J
e converted
flow durat
April is con
t the above
GFS averag
equency cur
hly flow freq
of Chipota falls
18
duration cu
ntioned ave
ability of t
June 2016.
d average v
tion curve a
nsistent wit
results for r
ge monthly
rve.
quency curv
hydropower st
urve of the C
erage month
he data, th
The averag
value, which
acquired thr
th the actu
relevant cal
flow" in Ta
ve of the CH
tation
CHIPOTA F
hly flow du
he team con
ge flow in J
h is 0.71m3
rough conv
ual results.
lculation.
able 2-2 to
HIPOTA FA
FALLS SITE
uration curv
nducted a
June is 0.7m
3/s. This sh
verting the
Therefore,
make empi
ALLS SITE
E
ve at
field
m3/s,
hows
field
the
rical
Feasibility report of Chipota falls hydropower station
19
2.4 Runoff
The hydrological data is limited and the project is very unique. The power
station only needs to meet the community households’ demand for electricity;
therefore, there will be no damage to the waterfall landscape. Considering that the
only power supplier requires a high guarantee rate, the design guarantee rate is 75%.
Please check the frequency curve and Q75%=0.4m3/s which supports this claim.
Table 2-3 CHIPOTA Station Site Design Monthly Runoff Table
Item Design monthly runoff (m3/s)
25% 50% 75%
CHIPOTA
hydropower station 1.14 0.68 0.40
2.5 Flood
According to the introduction of headman KABAMBA at the location of the
MULEMBO River, floodwaters will submerg the road bridge upstream the dam site.
The bridge is 1422.23m high and 12m wide, and the riverbed elevation at the bottom
of the bridge is about 1419.50m. Assuming the depth of water at the bridge site is 3m
and the flow rate is 3m3/s, then the flood is estimated to be 110 m3/s of which the dam
will be able to accommodate.
2.6 Water-level Discharge Relation Curve at the Dam and Plant Site
Based on the measurement on the topographic maps of the CHIPOTA power
station in June 2016, we will intercept the river section at the dam site and plant, and
calculate the section flow by using the following formula:
Q ——cross-sectional flow
n ——River reach roughness
R ——Section hydraulic radius
AIRn
Q ×= 21
321
natu
of 5
sele
disc
tabl
Tab
Wat
d
Dis
Watpl
Dis
Accordin
ural river co
5‰, and the
ecting the tu
charge, and
le 2-4.
ble 2-4 Wat
ter level at th
dam site (m)
scharge (m3/s)
ter level at thlant site (m)
scharge (m3/s)
Figu
Feas
I
A
ng to the fie
ourse. The s
e roughness
urning poin
correcting t
ter-Level D
e 1419.5
) 2.2
e 1366
) 3.82
ure 2-3 Wate
sibility report of
——slope
——flow a
eld survey,
slope of the
s adopts 0.0
nt of section
the contrary
ischarge Re
Dam
1420
10.58
1366.5
11.23
er-level Dis
of Chipota falls
20
of the hydra
area, m2
the river w
e water surf
04. We calcu
n, checking
y inflection
elation of th
m and Plant
1421
39.18
1367
19.93
scharge Rela
hydropower st
aulic grade
where the po
face approxi
ulated the f
the relation
amount. Th
he Natural R
Site
1422
68.41 1
1368
46.57
ation Curve
tation
line
ower station
imately ado
flow at each
n between w
he calculatio
River Course
1423 1
100.38 17
1369 1
86.73 13
e at the Dam
n is located
opts the ave
h water leve
water level
on results ar
e at CHIPO
1424 14
73.21 235
1370 13
38.20 200
m Site
d is a
erage
el by
and
re in
OTA
425
5.02
371
0.35
2.7
with
sedi
水位
()
Figu
Sediment
The catch
h less hum
iment quant
1365
1366
1367
1368
1369
1370
1371
1372
0
水位
(m)
Feas
ure 2-4 Wate
hment above
man activity
tity in the ri
50
sibility report of
er-level Dis
e the CHIP
y effect and
iver is small
100
流
厂址水
of Chipota falls
21
charge Rela
POTA powe
d very low
l.
0 150
流量(m3/s)
位流量关系
hydropower st
ation Curve
er station ha
w water an
0 20
系曲线
tation
at the Plant
as thick gro
nd soil eros
00 25
t Site
ound vegeta
sion. Thus,
50
系列1
ation
the
Feasibility report of Chipota falls hydropower station
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2.8 Attached Figures
Figure 2-5 Schematic Diagram of CHIPOTA Site Upstream Basin
Fi
igure 2-6 Sc
Feas
chematic D
sibility report of
iagram of G
of Chipota falls
23
General Lay
hydropower st
yout of the C
tation
CHIPOTA PPower Station
Feasibility report of Chipota falls hydropower station
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Figure 2-7 Topography and Geomorphology in CHIPOTA Power Station Area
Feasibility report of Chipota falls hydropower station
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Chapter 3 Engineering Geology
3.1 Overview
The MULEMBO River is located in CHELA TAMBULE village (where the
headman KABAMBA resides), SERENJE region of the Central Province of Zambia.
It originates from the Muchinga Mountains. There is little geological data for this
project. After an on-site survey, the ground covering layer in the area is not thick and
rocks are exposed. Base on the preliminary judgment, the rocks at the location are
estimated to be basalts, with the rock mass being quite hard. The place is in a good
geological condition.
3.2 Regional Geology
3.2.1 Landform The site is located in a platform fracture zone. Through long-term erosion of
river, the platform broke into sections lengthwise along the river and formed
multiple-cascade waterfalls. On the left bank of the river there is dense forest and
steep mountains. There is another small tributary on the left of the ridge. The
mountain body on the right is relatively flat. A relatively flat and open sloping field at
the same elevation position of the last-cascade waterfall can be found. The forest there
is flourishing, but relatively sparse. Traffic passage is on the right side of the river.
The area above the visible first-cascade waterfall is flat grassland, which is not
eligible for storage.
3.2.2 Strata lithology The site selection was conducted without carrying out a geological survey but
with only a general field visit. No bad geological structure was found at the dam site
and above, and some of rocks at the riverbed are exposed and are estimated to be
basalts. The grassland on both banks of the river are flat. Thus, the excavation of the
dam foundation will be relatively simple.
The riverbed ladders below the dam site are fault scarps, forming cascade
waterfalls. The rock is dark red, and estimated to be karst-rock, a kind of basalt. The
Feasibility report of Chipota falls hydropower station
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rock is hard and has high compressive strength.
The area where the plant will be built is a gentle sloping field, where the rock is
exposed and the rock property is the same as the riverbed.
3.2.3 Geological structure Zambia is a typical inland country, and its territory is on a plateau with little
undulation. The landscape is hilly by appearance, with the average elevation being
above 1000m. The topography of the land slopes from the northeast to the southwest.
The Zambia River and its tributaries, the Kafue River and the Luangwa River, flow
from north to south, while the Zambezi River flows from east to west into the Luapula
River.
3.2.4 Hydrological geology The layer is generally 2-3m in thickness, not very thick where underground
water is not found. But, abundant quaternary phreatic water is distributed in the
quaternary unconsolidated formation at the small valley
3.3 Natural Building Materials
The place around the site is the basalt area, and the rock is available for water
conservancy engineering. In the valley near the site, there is silver sand; however, it is
of high silt content and only suitable to be used as mortar, but not for any of the
structural sections. The timber is mainly weed trees which can be used as auxiliary
material for scaffolding, while the building materials will need to be purchased..
3.4 Conclusions and Suggestions
1. The penstock anchorage block (pier) foundation is made of gravel soil or
gravel containing low liquid limit clay as the bearing layer. The characteristic values
of the bearing force are 260kPa and 220kPa respectively.
2. The soil covering where the plant foundation will be built is very thin; thus, a
masonry foundation should be used.
Feasibility report of Chipota falls hydropower station
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Figure 3-1 Regional Geological Structure
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Chapter 4 Engineering Tasks and Scale
4.1 General Situation
4.1.1 Physical geography
Zambia is located in the inland plateau in the middle, southern part of the African
continent. The elevation ranges between 1000m to 1500m for most of the region,
sloping from northeast to southwest.
Zambia has a mild and cool tropical savanna climate, with an average annual
temperature between 18~20℃. It has three seasons: from May to August, it is the dry,
cool season, with the temperature between 14 ~ 32℃, a harvest season for most crops;
from September to October, it is the dry, hot season, with the temperature between 26
~ 32℃; from November to April, it is the warm, wet season, with the temperature
lower than the dry and cool season. Most of the rainfall in a year occurs during this
season. Annual rainfall is about 1400mm in the northern part, gradually reduces
toward the southern part to 700mm.
CHIPOTA hydropower station is located on the MULEMBO River (where the
headman KABAMBA resides), CHELA TAMBULE village, SERENJE region of the
Central Province of Zambia. The river is the third-order tributary of Zambezi River
(first-order tributary is the Luangwa River, and the second-order tributary is
Lukasashi River). The site is 400 km away from Lusaka, the capital. The geographical
location is latitude 13°13' 4.8" S, longitude 30°25' 52.24" E.
4.1.2 Social and economic situation
The main economic pillars in Zambia include agriculture, mining and services.
The economy is heavily reliant on the copper mining industry. Therefore, its economy
often fluctuates with the changes of mineral industry. In order to change this situation
and promote sustainable development, the government has decided to implement
economic diversification and market oriented economic policies, focusing on the
development of agriculture, tourism, gem development, hydropower and other
Feasibility report of Chipota falls hydropower station
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competitive industries. At present, the economy has achieved continuous growth in
successive years. According to the statistics in 2014 made by the World Bank,
Zambia's GDP and GDP per capita were 27.07 billion USD and 1802 USD
respectively. The actual growth rate and inflation rate in 2014 were estimated to be
5.6% and 7.9%. Therefore, Zambia has a lower middle-income economy.
4.1.3 Hydropower resources and the development and utilization situation Africa has 40% of the world's hydropower resources, but suffering a power
shortage. But, only 8% of the hydropower resources of the entire African continent
have been developed. At present, there are still more than 500 million people without
access to electricity services, and electrification is particularly important in rural areas.
Most small hydropower stations are located in remote rural areas, and they play an
important role for the electrification, promotion of local production, improvement on
living standards and employment in these areas.
Zambia is located in the middle southern part of Africa with abundant water
resources, accounting for 45% of Southern Africa’s water resources. The hydropower
potential is preliminarily estimated to be 6765MW, in which 1715MW has been
developed. Therefore, Zambia has paid much attention on the investment of
hydropower projects.
4.1.4 Necessity of the project This region is endowed with a large potential of mineral resources, forest and
rich water resources, but the development level is not high. Most of the people there
rely on agriculture to make a living. The social and economic conditions in the region
are still at a moderate level in Zambia.
In the area near the site the population is about 15000. There are many
communities in the area, as well as a primary school, junior high school (high school
to be built), hospital and local court. As per investigation, the residents here have
neither electric lighting nor other electrical means of consumption. Only a few
residents achieve lighting electricity through household solar energy devices. This
project will supply electricity for household use, as well as for the processing of
agricultural products. Tt will increase the electrification and reduce the consumption
of biological fuel and improve the ecological environment. Therefore, the
construction of CHIPOTA hydropower station is critical.
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4.2 Scale of Power Generation Projects
4.2.1 Power supply range and load forecast After consulting the Zambian side, the supply range of this project is identified
to only include the 15,000 consumers within the area of the site. Taking 10W/person
as the electricity consumption per capita, 80% as the simultaneity rate for electricity
consumption, the current maximum electricity load is 120KW. Taking the estimated
electrical consumption in the next 5~10 years and the protection of the waterfall
landscape into consideration, the installed capacity of the power station is
preliminarily identified to be 200kW, which can meet the present demands, as well
future demands.
4.2.2 Drafting of the scheme As per the topographic and geologic conditions, two schemes are drafted in the
feasibility study and compare different selections of the dam site, plant site and water
diversion method as follows:
Scheme I: The dam is about 25m upstream the existing bridge and the
powerhouse is on the flat land at the bottom of the gentle slope on the right bank of
the 4th cascade waterfall. Water is diverted to the pressure forebay through an open
canal and then diverted to the power house by penstocks.
Scheme II: The dam is located at about 25m downstream the existing bridge and
the powerhouse on the hillside half-way up the gentle slope on the right bank of the
4th cascade waterfall. Water is diverted directly from the dam to the power house by
penstocks.
The advantages and disadvantages of the two schemes are shown in table 4-1.
Table 4-1 Comparison of the two schemes
Item Advantages and disadvantages
Advantages Disadvantages
Feasibility report of Chipota falls hydropower station
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Scheme I
1. The dam will be upstream of the little bridge, with a shorter dam axis andsmaller amount of labor. 2. With a crest elevation of 1422m, the head loss of the open canal is small. 3. The power house is close to the riverbed, on flat ground, with small excavation quantity and short tailrace.
1. Because the dam is located upstream the little bridge, the diversion structure shall be lengthened which will go across the road, leading to an increase of labor time, and a more difficult construction and construction diversion. 2. An open canal occupies a larger area. A greater amount of excavation and abandoned slags are liable to cause soil erosion and damage the ecological environment. The construction of an open canal needs a large quantity of aggregates and a pressure forebay at the end needs to be built, so the construction period will be longer. 3. The ground elevation of the power house is low which does not meet the flood prevention requirement and will influence the safety.
Scheme II
1. The dam is located downstream the little bridge. The broad downstream riverbed supports construction diversion. 2. Penstock has little effect on the ecological environment, needs small earth-rock project quantity and short construction period and is convenient for the management and maintenance in the following operation. 3. The layout of the plant area is rational, which is in favor of the delivery and installation of the equipment. It avoids the impact of a flood, favoring the safety of the power station.
1. With longer dam axis, the project quantity is increased. 2. With a crest elevation of 1421.5m, the penstock head loss is increased.
Taking all factors into consideration, Scheme II is more suitable and is
recommended by this feasibility study.
4.2.3 Calculation of hydropower and installed capacity selection Based on the actually measured CHIPOTA topographic map and taking the
influence of backup water level and mounting elevation of the units into consideration,
the gross water head of the power station will be 50.0m. As per the preliminary layout
plan, the penstock will be about 530m long. According to the hydrological calculation,
the design average monthly flow at the site will be Q50%=0.68m3/s, which is identified
as the design reference flow. As an only power supply, the station needs a high
guarantee rate. The design guarantee rate of the power station is identified to be 75%
and the guarantee flow is Q75%=0.4m3/s.
(1) Calculation of pipe diameter
The pipe diameter is calculated as per the following formula:
Feasibility report of Chipota falls hydropower station
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732.5
HQD =
In the formula: D=pipe diameter(m);
Q=Reference flow (m3/s),Q50%=0.68 m3/s;
H=Calculated head (m),H=50.00m;
The pipe diameter of the penstock at the CHIPOTA hydropower station is
D=0.65m;
(2) Calculation of head loss
The penstock of CHIPOTA hydropower station is 530m long, and the frictional
head loss is calculated as per the following formula:
In the formula: L=Pipe length(m),L=530m;
D=Pipe diameter(m),D=0.65m;
V=Flow rate in pipe (m/s),V=2.05m/s;
Partial head loss is calculated as per the following formula:
∑h 局=g
V
2
2
⋅ζ
Table 4-2 Statistical Table of the Partial Head Loss Coefficient
Loss position ζvalue Quantity Total Horn mouth 0.2 1 0.2
Bottom valve 0.7 1 0.7 Gate valve 0.1 1 0.1
Elbow and bend 0.3 3 0.9 Gate slot 0.2 1 0.2
Total 2.1 The total head loss is h△ frictional+∑hlocal=4.17+0.45=4.62m
So the net head of power station is: hnet=50.00-4.62=45.38m。
(3) Calculation of hydroenergy
1) Calculation of guarantee output
When the design guarantee output P=75%,the guarantee flow Q75%=0.4m3/s,
the corresponding head loss will be 1.65m and the net head is 48.35m.
When the average output coefficient is proposed to be 8.0, then the guarantee
Feasibility report of Chipota falls hydropower station
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output is:
Nguarantee=A×Qguarantee×Hguarantee=8.0×0.4×48.35=154.72kW
2) Calculation of average output
When the design guarantee output P=50%,the average flow Q50%=0.68m3/s,
the corresponding head loss will be 4.62m and the net head is 45.38m.
Ndesign= A×Qdesign×Hdesign=8.0×0.68×45.38=246.87kW
(4) Installed capacity selection
1) Select the installed capacity based on the guarantee output. Considering the
requirement for power supply reliability, taking 1.5 as the installation coefficient, the
installed capacity of the power station is 232.08kW.
2) When selecting the installed capacity based on the average output and the
installed capacity of the power station is 246.87kW.
When ensuring the electricity supply and the waterfall landscape, installed
capacity of the power station is preliminarily identified to be 2×100kW.
Feasibility report of Chipota falls hydropower station
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The index of the hydropower station is shown in Table 4-3.
Table 4-3: Table of Calculation Results of Hydroenergy Index
Item Index
CHIPOTA hydropower station:
Design head(m) 45.38
Guarantee flow(m³/s) 0.40
Guarantee output(kW) 154.72
Installed capacity(kW) 2×100
Average annual power generation capacity
(104 kW.h) 135.53
Annual utilization hours(h) 6777
Feasibility report of Chipota falls hydropower station
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Chapter 5 Project layout and main buildings
5.1 Design basis
5.1.1 Main technical specifications and references (1) Standard for Classification and Flood Control of Water Resources and
Hydroelectric Project SL252-2000; (2) Design Specification for Stonemasonry Dam SL25-2006; (3) Specifications for Seismic Sesign of Hydraulic Structures SL203-97; (4) Design Code for Hydropower House SL266-2014; (5) Design Specification for Intake of Hydraulic and Hydroelectric Engineering
SL285—2003; (6)Code for Fire Protection Design of Hydraulic and Hydroelectric Engineering
SL329—2005; (7) Design Criterion ofReservoir Management SL106—96; (8) Hydraulic Design Handbook.
5.1.2 Basic design information (1) Task for engineering development
With an installed capacity of 2×100kW and a design annual power generation of
1.3553 million kWh, the engineering task of CHIPOTA hydropower station is mainly
for power generation.
(2) Rock physical and mechanical indexes
Dam foundation physical and mechanical indexes adopted in the stability
analysis and calculation are as follows:
(3)Weak weathered basalt:
Bulk density:2.69-2.73g/cm³;porosity: 0.73%-1.10%;
Saturated compressive strength: 700—800kg/cm2.
Friction coefficient f rock/rock=0.55-0.65
f concrete/rock=0.60-0.65
(4) Dam body anti-slide stability safety coefficient
Basic combination (normal operation condition): Kc≥1.05
Special combination (check condition): Kc≥1.00
(5) Seismic intensity
Feasibility report of Chipota falls hydropower station
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With seismic intensity being less than VI degree, seismic defense will not be
considered.
5.1.3 Project grade and standards CHIPOTA hydro power station is a hydro power project aiming at power
generation, with a maximum dam height of 3.5m and an installed capacity of 2×
100kW. According to Design Code for Small Hydropower Station (GB50071-2002),
this project is a V grade project, with the dam, power house and penstock of its main
construction being in the category of 5thgrade and other temporary constructions of
the 5thgrade. See table 5-1 for the construction grade and the corresponding flood
standards.
Table 5-1 Construction grade and flood standards
Construction Grade Flood standard
(recurrence interval) Design Check
Dam 5 10 20 Power house 5 20 50 Penstock 5 10 20 Other temporary construction 5 5 Note: Due to lack of flood data, the actual check flood is estimated to be 110m3
/s.
5.2 Project location and general layout
5.2.1 Location of the dam Dam site plans
The site of the dam shall be located at a suitable place upstream from the 1st
stage waterfall. There will be a traffic bridge and road about 50m upstream from the
waterfall. With exposed rock and a shallow coverage layer, the geological conditions
are good. Both banks of the dam site are flat grasslands, without requisite conditions
for a reservoir. Through field reconnaissance, two feasible options of dam sites for
CHIPOTA hydropower station are decided: the upper site is 25m upstream from the
traffic bridge and the lower site is 25m downstream from the traffic bridge, which are
50m apart. Comparison shall be made based on the aspects of topography, geology,
flood impact, construction, water head utilization, etc., and the optimum shall be
adopted.
Feasibility report of Chipota falls hydropower station
37
Comparison of the plans
From the view of topography: 1. Mountains on either bank of the upper dam site
are basically symmetrical. The water flow is straight and unhindered with a riverbed
elevation of 1419.70m;
2. Mountains on the banks of the lower dam site are asymmetrical with left bank
steep and right bank flat. The riverbed changes from narrow to wide with an elevation
of 1419.30m and the long dam axis is favorable for the flood discharge and energy
dissipation.
From the view of geology: the two dam sites are not far apart, with similar
lithology of the bedrock at the under-part of the riverbed and basically the same
hydrogeological condition. Both upper and lower dam sites are of granite geology
with hard and intact rock. There is no large fault passing by near the dam site that will
cause instability and leakage.
From the view of flood impact: 1. The upper dam site locates upstream from the
traffic bridge, when discharging flood, no farmland, buildings, etc., will be submerged,
so the dam height has only to meet the requirement for water diversion.
2. The lower dam site locates downstream from the traffic bridge and the
normal pool level of the dam will be restricted by the traffic bridge. When discharging
flood, the submergence depth of the traffic bridge increases (according to on-site
survey, the traffic bridge was always submerged during the flood season over the
years); however, due to less utilization of the bridge, short-term submergence will not
bring about any big effect.
From the view of construction: 1. With a shorter dam axis, the upper dam site
needs correspondingly smaller work quantities; however, its thicker covering layer
will lead to bigger excavation quantity. The diversion structure shall be lengthened
which will go across the road, leading to an increase of work quantities, harder
construction, longer construction period and harder construction diversion.
2. With a longer dam axis, the lower dam site needs larger work quantities for
the dam body; however, the work quantity for the diversion structure will be reduced,
crossing with the road will be avoided and it will be much easier for construction
diversion.
From the view of water head utilization: the normal pool level of the upper dam
site is 1422.00m, while the lower dam site is 1421.50m. With a difference of 0.5m,
the advantage in water head utilization is not obvious.
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Through comparison, the two dam sites are near to each other, with basically the
same topographic and geologic conditions. Both have no submergence loss and little
impact from flood. They have little difference in water head. However, the upper dam
site has larger diversion structure quantities and the diversion structure spreads across
the road causing more difficult construction and diversion, as well as a longer
construction period. For the lower dam site, though its dam body quantities will be
slightly larger than the upper dam site, the length of the diversion structure will be
shortened, crossing with the road will be avoided and it will be much easier for
construction diversion at the same time.
Taking all factors into consideration, the lower dam site, which is more rational,
will be the suggested plan of this feasibility study.
Figure 5-1 Bridge near dam site
5.2.2 Location of the power house Power house site plan
The power house will be located on the gentle slope of the right bank at the same
elevation with the last stage seeable waterfall (riprap bridge). According to field
reconnaissance and topographic maps and taking the factors of water head utilization,
geological conditions, layout of the penstock, tailwater connection, basic excavation
quantity, etc., into consideration, the optimum plan shall be decided.
Plan I: The power house shall be located at the bottom of the gentle slope, in the
open area on the right bank close to the riverbed. The ground elevation is
1367.00m~1368.00m and the design elevation of the power house shall be 1367.50m.
Plan II: The power house shall be located on the slope half-way up the gentle
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slope, with the ground elevation of 1371.0m~1373.0m and power house design
elevation of 1371.50m.
Comparison of the plans
From the view of water head utilization: the ground elevation of Plan I is 4.00m
lower than Plan II, so the utilizable water head of Plan I is higher.
From the view of plant area layout: for Plan I, the plant site is flat with the gate
of the power house facing southwest and the booster station being placed behind the
power house. For Plan II, the ground elevation is higher than Plan I and there is open
ground in front of the southwestward gate which connects the access road naturally.
The booster station locates at the upstream side of the power house, which facilitates
the transport and installation of the equipment.
From the view of tailwater connection: according to the units installation
drawing, now that the bottom plate elevation of the tailwater pit is 1.55m lower than
the ground elevation of the power house and the design water depth is 0.2m, the
tailwater level of Plan I is 1366.15m, while that of Plan II is 1370.15m. Through field
survey and consultation with local residents, the submergence water level over the
years was about 1369.50m, so Plan I fails to meet the flood prevention requirement.
When a flood comes, there is a risk of tailwater reverse flow, which affects the normal
operation of the power station.
From the view of foundation excavation quantity: Plan I has an open and flat
ground, needing smaller foundation excavation quantity while Plan II needs a slightly
larger foundation excavation quantity than Plan I.
Take all factors into consideration, Plan II is more rational and will be the
recommended plan of this feasibility study.
Figure 5-2 riprap bridge and sloping land near the plant site
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5.2.3 Selection of water diversion method Water diversion plan
Based on the comparison in chapter 4, the two diversion methods of open canal
diversion and penstock diversion are proposed. Take the aspects of water head
utilization, construction condition, environment impact, project management, project
investment, etc. into consideration and choose the best the plan.
Plan I applies an open canal to divert water. The open canal is laid along the
contour on the right bank of the river course, connecting to a pressure forebay at the
end. After the forebay, there is pipeline laid along the hillside to the power house.
Plan II applies a penstock to divert water. The penstock goes out directly from
the dam to the power house along the hillside on the right bank of the river course
according to landform.
Comparison of the plans
From the view of water head utilization, open canal diversion for small
hydropower station normally adopts 1/1000 canal slope with smaller water head loss
than penstocks, therefore, the gross water head in Plan I is higher than Plan II.
From the view of construction condition, the construction of open canal in Plan I
needs a large quantity of aggregates. A pressure forebay at the end needs to be built. A
lack of local labor and field mining of stone materials will lead to a slow construction
progress and long construction period. Plan II applies penstocks to divert water for
power generation directly from the dam, which requires fewer materials and a simpler
construction process, and the construction progress can be guaranteed under the
condition of less labor force.
From the view of environmental impact, an open canal in Plan I occupies a larger
area. A greater amount of excavation and abandoned slags are liable to cause soil
erosion and damage the ecological environment. While in Plan II, the laying of
penstocks needs smaller earth-rock quantities and a shorter construction period, which
causes little impact on ecological environment.
From the view of project administration, the open canal in Plan I crosses the
forest land. Litters like leaves are likely to accumulate. Regular cleaning is needed,
which increases the administrative cost. While in Plan II, the penstock is laid directly
from the dam to the power house. When water overflows the dam, litters like leaves
are not easy to accumulate, so it is convenient to maintain.
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From the view of project investment, Plan II adopts a penstock, which will
obviously cost more than Plan I.
In sum, Plan I features a higher utilizable water head and a smaller investment.
While its disadvantages in the aspects of ecology, construction period and
administration are prominent, the loss outweighs the gain. Though the investment of
Plan II is higher, the construction progress is faster. Being environment-friendly and
convenient in maintenance, Plan II is generally more rational. Therefore, Plan II will
be the recommended plan of this feasibility study.
Figure 5-3 Slope on the right bank
5.2.4 General layout of the project According to the comparison of the plans, the power station project in Plan I
(comparative plan) consists of a dam, an open canal, a pressure forebay, a penstock, a
power house, a tailrace, booster station etc. Plan II (recommended plan) consists of a
dam, penstock, power house, tailrace, booster station, etc. The dam will be located at
a suitable place upstream from the 1st stage waterfall. The open canal or penstock will
be laid on the right bank along the river. The power house will be on the right bank
gentle slope under the 4th stage waterfall. The booster station will be placed on the
opposite side of the power house.
5.3 Water retaining structures
5.3.1 Layout of the dam The dam will be a rubble concrete gravity dam, which will be designed based on
the requirements of Design Specification for Concrete Gravity Dams DL5018-1999
and relevant laws, rules and regulations, referring to dams of the same type. It will
also take into consideration the comprehensive factors of the natural geological
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conditions, natural building materials, the overall arrangement requirements of the
project, etc.
Plan I (comparative plan): according to the layout of the open canal, the dam
crest elevation is determined to be 1422.00m, 0.23m lower than the bridge deck. The
lowest foundation plane elevation is 1418.50m. The maximum dam height is 3.50m.
The dam axis length is 24.00m. The dam crest width is 1.50m, and the maximum dam
bottom width is 4.00m. The upstream face will be vertical and the downstream will
have a slope of 1:0.7. The overflow face uses a WES curve and underflow
energy dissipation is adopted.
Plan II (recommended plan): On the premise that the dam height meets the water
intake arrangement and hydraulic conditions, the elevation of the dam crest is set to
be 1421.50m, 0.73m lower than the elevation of the small bridge deck. The lowest
foundation plane elevation is 1418.00m. The maximum dam height is 3.50m. The
dam axis length is 30.00m. The dam crest width is 1.50m, and the maximum dam
bottom width is 4.00m. The upstream face will be vertical and the downstream will
have a slope of 1:0.7. The overflow face uses a WES curve and underflow
energy dissipation is adopted.
5.3.2 Stability calculation Since the cross sections of the two plans are basically the same, stability
calculations are the same as well. Choose one of the plans for calculation, taking Plan
II as an example:
(1) The gravity dam calculation shall be performed as per the requirements of
Design Specification for Concrete Gravity Dams DL5018-1999, shear resistance
strength formula shall be used for sliding resistance stability calculation and the
material mechanics method shall be applied in the stress calculation.
(2) Calculation conditions
Normal pool water level is 1421.50m and there is no water downstream.
Design flood level: (none).
Check flood level is 1423.00m and the corresponding downstream water level is
1422.30m.
Riverbed elevation is 1419.30m.
Shear resistance friction coefficient in riverbed stability calculation f=0.55.
(3) Load combination
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The following three combinations of load are the control condition of gravity
dam stability calculation.
a. Basic combination: reservoir normal water level without downstream water,
self-weight of the dam and uplift pressure, etc.
b. Special combination: check flood level and corresponding downstream water
level, self-weight of the dam, uplift pressure, etc.
(4) Stress calculation results
The material mechanics method is applied in the stress calculation, see table 5-2
for the results. We can know from the table that the stress value should meet the
requirements of design specification.
Table 5-2 Stress Calculation Results unit: Kpa
Calculation condition Dam
σ1(Upstream side) σ2(Downstream side)
Basic combination 218.33 331.23
Special combination 182.98 366.58
(5) Sliding resistance stability calculation results
Shear resistance strength formula is applied for sliding resistance stability
calculation, see table 5-3 for the results. The calculation results meet the requirements
of the specification.
Table 5-3 Foundation Plane Sliding Resistance Stability Calculation Results
Calculation condition Basic combination Special combination
Dam 1.59 1.36
5.3.3 Flood discharge and energy dissipation facilities According to the design, a WES practical weir is adopted as an overflow weir.
Since the overflow weir is not high and the downstream riverbed foundation is good,
underflow energy dissipation is applied and no other dissipation engineering is
needed.
5.4 Open canal diversion method (comparative plan)
5.4.1 Open canal Plan I adopts an open canal to divert water, with a design discharge velocityof
0.68 m3/s and a canal length about 380m. The longitudinal slope adopts 1/1000. After
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44
calculation, a 1.2m×1.4m canal cross section can meet the requirement and the
design water depth is 0.75m. The canal uses M7.5 stone masonry lining with M10
mortar finishing on the inner side and 100mm thick C20 concrete for the bottom plate.
5.4.2 Pressure forebay In Plan I, the water diverted from the open canal shall be regulated by a pressure
forebay before entering the penstock.
According to the layout of the project diversion system, the forebay shall be laid
on the hillside of the right bank. The design dimension of the cross section is 6.0m
long, 5.0m wide and 4.0m deep. A stone masonry side wall and 200mm thick C20
concrete inner lining are adopted for seepage prevention, and the bottom plate shall be
poured with 250mm C20 concrete.
(1) Normal water level
Normal water level of canal end, i.e., the normal water level of pressure forebay
is 1422.0m.
(2) Lowest water level
The minimum water depth to prevent pressure the forebay from producing
cyclones is calculated as per the following formula:
of which,
C=coefficient, 0.5~0.7, symmetric water intake applies the smaller value
V=water velocity inside the pipe, in full capacity operation V=2.05m/s
A=diameter of the pipe
It is calculated that the power station △h=1.22 m and the lowest water level is
1420.78.
(3) Highest water level
Considering the actual landform of the forebay, the spillway will not be set in the
forebay. Instead, it will be located close to the riverbed upstream the canal. The
overflow weir of the spillway adopts a WES practical weir, with a water depth of
0.3m, therefore, the highest water level of the forebay is:
∇H highest=1422.00+0.3+304*1/1000=1422.60m
(4) Forebay roof elevation
The highest water level of the forebay plus 0.3m safety freeboard is the roof
elevation of CHIPOTA power station
21
aVCh =Δ
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forebay∇H=1422.60+0.3=1422.90m.
(5) Forebay width
According to the actual landform and the requirement of the forebay regulation
volume, the design net width of the forebay in CHIPOTA hydropower station is 6m.
(6) Forebay length
According to the landform and the regulation volume, the forebay length of
CHIPOTA hydropower station is 5m, the total forebay volume is 120 m3 and the
regulation volume is 75m3.
5.5 Penstock (recommended plan)
(1) Selection of the pipeline
In order to guarantee the safe operation of the penstock, the pipeline is laid
mostly along the stable ridge with the total length of the penstock’s main pipe being
530m.
(2) Configuration of the pipeline
According to the specification, an exposed penstock structural analysis method is
applied to calculate the penstock. The main pipe axis is 530m long, with 6 anchorage
blocks and 6 expansion joints along the line. The diameter of the main pipe is 650mm,
the pipe wall thickness is 6-8mm calculated as per the initial estimate formulaδ≥
[PD]/[2φ〔σ〕](the allowed stress 〔σ〕is 160Mpa) and the space between
supporting piers is 5-8m. The total weight of metal works is about 69t.
(5) Anchorage blocks and supporting piers
The anchorage block balances the axial unbalanced force caused by the turning
of the penstock by its self-weight. The anchorage blocks will be built on a rock
foundation with greater base dimensions; thus, the foundation stress will meet the
requirement and recheck will not be performed. The weights of the anchorage block
need shall be calculated as per formula ∑∑ − Yf
XKG=
, with the safety coefficient
K=1.5, and the friction coefficient between anchorage block and rock foundation
f=0.5. The weight of each anchorage block is calculated and listed in the following
table. Anchorage block 6#, with a larger size and buried underground, will be used in
the bifurcation of the main pipe and needs no calculation.
Anchorage Block center Block center Weight for Volume for Actual
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block No. elevation (m) design water
head (m)
block
calculation (t)
block
calculation (m3)
volume of the
block (m3)
1# 1420.00 1.50 86.08 35.87 36.75
2# 1417.00 4.50 77.75 32.40 32.40
3# 1411.75 9.75 22.22 9.26 18.00
4# 1406.05 15.45 25.66 10.69 18.00
5# 1388.30 33.20 25.64 10.68 18.00
The supporting pier balances the normal component forces from the weights of
the penstock, the water inside the pipe, the friction force between the steel pipe
support and the pier by its self-weight. With greater actual volume and most of it
being buried underground, the supporting pier bears smaller horizontal force; thus, the
requirements can be met.
5.6 Power house and booster station
5.6.1 Selection of the power house location The power house is of the diversion type ground power house. It will be placed
on the right bank gentle slope under the 4th waterfall, taking factors of topographical,
geological and traffic conditions into consideration. According to the comparison of
the power house site plans, Plan II is more rational than Plan I. The power house shall
be located halfway up the gentle slope, with a ground elevation of 1371.00m~
1373.00m, and a power house design ground elevation of 1371.50m. The design
tailwater level is 1370.15m, 0.65m higher than the submergence water level.
5.6.2 Power house structure The power house applies a masonry structure. According to the layout and the
mounting requirements of the generators, the space between generators shall be 5.0m.
The dimension of the power house is 12×6.8×4.5m and the roof applies a light, steel
roof truss.
5.6.3 Booster station The booster station is placed on the opposite side of the power house, with a
plane dimension of 5×5m and the ground elevation of 1371.50m. The main
transformer is located at the side close to the power house.
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5.6.4 Housing for the use of administration The housing for the use of administration applies a masonry structure, which is a
1-story, 2-bay building very near to the entrance road, with an area of 20m2.
After the completion of the main works in the plant area, treatment shall be taken
to the disturbed slope and the revetment. Afforestation and beautification of the
environment shall be carried out as well to make the plant area look tidy.
5.6.5 Entrance road The traffic is convenient in the plant area. There is only a need to select a route
from near the dam to build a road with sand-gravel pavement 3.5m wide and about
650m long.
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Chapter 6 Electromechanical and metal structures
CHIPOTA hydropower station has an installed capacity of 200kW, with 2×
100kW units installed. The model of the turbine is XJA-W-46/1×11. The model of
the two generators is SFW100-10/740. There are two speed governors, and two sets of
φ400 intake valves as well. A plane metal gate shall be installed at the intake of the
dam equipped with a 2t manual screw hoist. The dimension of the gate is(width×
height)0.9m×0.9m. There shall be a φ300 gate valve at the sand flushing orifice.
6.1 Units
(1) Power station original data
Normal water level: 1421.50m
Ground elevation of the power house: 1371.50m
Design tailwater level: 1370.15m
Installed capacity: 200kW
Installed sets: 2
Guaranteed output: 154.72kW
Annual power generation: 1.3553 million kWh
Annual utilization hours: 6777h
Design water head: 45.38m
(2) Selection of turbine type
Based on hydropower calculation, with design water head being 45.38m and a
monthly average discharge being 0.4m3/s when the design guaranteed ratio is 75%
(the guaranteed output is 154.72kW), 2 sets of units with 100kW unit capacity are
selected.
Since the water head of the power station is 45.38m, the following types of units
can be suitable: Francis turbine, Turgo turbine and cross-flow turbine. Below is a
comparison of the representative units that suit the water head of the power station.
The Francis turbine gives higher efficiency at rated point and higher utilization
of water head; however, it’s more complicated than the other two, and with a smaller
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runner it is more difficult to manufacture. The efficiency of Turgo turbine is relatively
lower, but with a simple structure it is convenient to maintain and it has a wider
working condition range at rated point. The cross-flow turbine has higher efficiency
than the Turgo turbine, a simple structure and smaller unit power output; however,
there are fewer factories producing this type at the present. After comprehensive
comparison, model XJA-W-46/1×11 units are selected.
Turbine model: XJA-W-46/1×11.5
Rated water head: 46m
Rated discharge: 0.34m/s
Rated output: 111kW
Rated rotation speed: 600r/min
Generator model: SFW100—10/740
Rate capacity: 100kW
Rated voltage: 0.4kV
Power factor: 0.8
Speed governor model: CJWT-1
Excitation: generator matched static silicon controlled excitation
Intake valve model:Z941H—10φ400
(4) Selection of the auxiliary equipment
a. Inner plant hoisting machine
In the installation of the units, the maximum hoisted parts in the plant are 2.5t.
Mobile profiled-steel-made supporting frame is adopted, equipped with a manual
hoist with a lifting capacity of 5t.
b. Technical water supply system of the units
Technical water supply shall be determined by the manufacturer of the units.
c. Drainage system
The cooling water and other seepage water shall be drained directly to the
downstream riverbed.
d. Oil system
The quantity of turbine oil and insulation oil in this power station is small, so two
0.2m3 gasoline barrels shall be equipped.
e. Maintenance tools
In order to meet the requirements for maintenance and exchange of operating
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units and the auxiliary equipment, this power station shall be equipped with one set of
tools for routine maintenance.
Table 6-1 Hydraulic mechanical equipment table
No. Name Equipment specification & model
Quantity
1 Turbine XJA-W-46/1×11 2 sets
2 Generator SFW100-10/740 2 sets
3 Speed governor CJWT-1 2 sets
4 Excitation Static silicon controlled excitation
2 sets
5 Intake valve Z941H-10φ400 2 sets
6.2 Access mode to power system and main electrical connection
6.2.1 Access mode to power system The residents in the nearby areas of the power station mostly have no access to
illumination and other household electricity. It is known that very few residents have
solved the problem of illumination through household solar devices. This power
station will power a population of 15,000 in the nearby areas. There is no power grid
nearby, thus, the station will operate off the grid. The total installed capacity of this
power station will be 2×100kW and annual power generation will be 1.3553 million
kW.h. The distance from the power station to the supply area is 10km. A 11kV line
will be adopted to deliver electricity to the community. After the voltage is reduced to
400V, the electricity will be supplied to the users.
6.2.2 Main connection (1) Connection of the generator voltage side and increased voltage side
There are 2 sets of units in this power station. The rated voltage of the generator
is 0.4kV. There is one single circuit of outgoing line from the high voltage side,
without nearby loads. According to the combination of generator and transformer, the
two types of main connection schemes are analyzed, see figure 6-1 for details.
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Scheme 1 Scheme 2
Figure 6-1 Scheme 1: Enlarging unit connection is adopted at the generator voltage side and
the two units share one main transformer; transformer-line group connection is
adopted at the increased voltage side. Connection of this scheme is simple and clear
and is convenient to maintain. It simplifies the connection at the high voltage side,
occupies less land and needs smaller excavation and less investment. Its disadvantage
is that when the main transformer is under failure or overhaul, the electricity from the
two generators can’t be transmitted. However, the failure rate of the main transformer
is low, requiring longer overhaul cycle and shorter outage time.
Scheme 2: Unit connection is adopted at the generator voltage side, with one unit
connecting to one transformer; Single bus connection is adopted at the increased
voltage side. This scheme operates flexibly. With small failure influence range and
simple relay protection, it features higher reliability. However, there will be more high
voltage electrical equipment, leading to increases of space for equipment layout and
investment on the whole electrical connection. Based on the above analysis and considering the actual operation experience of
small-sized hydropower station, scheme 1 is recommended.
(2) Plant electricity, power supply to the plant area and dam area
The rated voltage of the generator is 0.4kV, so the plant electricity and the power
supply to the plant area will come directly from the 0.4/0.23kV voltage bus of the
generator.
One set of DC220/50Ah DC system shall be equipped.
Please refer to enclosed Main Electrical Connection Diagram.
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6.3 Selection of main electromechanical equipment
6.3.1 Short circuit current Because it operates as an independent system (take 0.8 as the power factor of the
system and 25kVA as the contralateral breaking capacity), the short circuit current of
the recommended electromechanical connection scheme is calculated. See Figure 6-2
for the system connection and equipment parameters and table 6-2 for the calculation
results of short circuit current.
10KVLG-3510Km
Figure 6-2
Table 6-2 The calculation of short circuit current
Short circuit point
T=0s Short circuit
current(KA)
T=0.6s Short circuit current
(KA)
T=1s Short circuit
current(KA)
Short circuit current peak value(KA)
d1 1.52 1.48 3.82
d2 6.94 3.87 18.01
6.3.2 Selection of the main electrical equipment The selection of electrical equipment form bases on the principle that it should
be advanced in technology, rational in economy and simple and convenient in
maintenance. It should also meet the requirements of latest regulations and
specifications.
Technical parameters of the electrical equipment are selected under normal
working conditions and the performances of the electrical equipment are examined as
per different short circuit circumstances. Both of the above two should be met at the
same time.
Preliminary selection
The control and distribution devices at the generator voltage side will apply a
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triad NDK-2001 low voltage generator unit with intelligent control panels, inside of
each installed with a ME-630A air circuit breaker, which is safe and reliable in
operation and convenient in maintenance. The outgoing lines of the generator will
adopt a ZR-VV22-120mm2 flame retardant PVC insulated cable, with one single line
per phase.
The switching device at the 11kV line side is of outdoor type, using a
ZW8-12/630 vacuum circuit breaker as its circuit breaker and GW1-10/630 as its
disconnector.
To match with the capacity of the generator, the main transformer will apply a
three-phase oil-immersed two copper core winding transformer with natural cooling.
According to the main connection design, its model is S11-250, 12.1±5%/0.4kV,
with a capacity of 250kVA.
Key parameters of the main electrical equipment with voltages of each level are
shown in enclosed diagram.
Check the equipment with short circuit current To simplify the calculation, take the total current of the corresponding short
points as the short circuit current to check the equipment. The full opening time of the
circuit breaker is 0.1s. Back-up protection action time at the 11kV side is 0.5s and the
thermal stability calculation time is tjs=0.6s; protection action time at the 0.4kV side
is 1s and the thermal stability calculation time is tjs=1s.
All the equipment selected has been checked to be acceptable.
Generator excitation
The generators in this power station adopt static silicon controlled excitation
system, which is powered directly by the generator. The excitation system shall be
supplied by the manufacturer of the generators.
Plant-service power supply and DC system
Plant-service power supply adopts a GGD distribution panel.
DC system of this power station adopts non-maintaining lead-acid battery, with
complete sets of DC equipment with a rated voltage of 220V and a capacity of 50 AH.
As the DC power source of the station, it shall meet the requirement for DC loads in
the operation of automatic devices for plant control, protection and safety, the
operation of circuit breakers, emergency lighting, etc.
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6.4 Layout of the electromechanical equipment
This power station applies a diversion-type ground power house located at the
right bank of the riverbed. The mounting site is at one side of the entrance gate of the
power house.
6.4.1 Inner-plant electrical equipment layout According to the layout characteristics of the main electrical connection and low
voltage horizontal hydro-generator, the two triad panels of the generator, two
excitation panels, one plant service panel and one DC panel shall all be placed at the
downstream side of the units.
6.4.2 Layout of the booster station According to the key project layout, topography and geomorphology near the
power station and the direction of the incoming and outgoing lines, the booster station
is located close to the power house opposite to the entrance gate of the power house.
This arrangement is simple and clear, featuring unhindered incoming and outgoing
lines, compact arrangement and less occupation of area.
Table 6-3 Electrical equipment material No. Name Specification Unit Qty A Generator & equipment nearby 1 Units control panel NDK-2001 pc 2 2 Excitation panel NWLC pc 2
3 Shared panel for wiring and main transformer
GGD-02 pc 1
4 Battery and charging feedback panel
pc 1
5 Plant electricity distribution box pc 2
B Main transformer and booster station equipment
1 Transformer S11-250/11 12.1/0.4kV set 2 2 11kV circuit breaker ZW8-12/630,630A set 1 3 11kV disconnector GW1-10/630A set 1 4 Voltage transformer JDZXW-11 set 1 5 11kV arrester YH5WS-12.7/50 set 1 C Conductor and cable 1 Cable ZR-VV 22-120,1kV m 200 2 Cable ZR-VV 22-70,1kV m 180 3 Cable ZR-VV-3×10+1×6, 0.6/1kV m 20 4 Cable kVVP7*1.5 m 300 D Lighting luminaire Indoor and outdoor set 1
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E Auxiliary equipment 1 Electricity pole Steel structure set 2
2 Pin insulator pc 3
3 Suspension insulating strip pc 6
4 Ball-end hoist pc 3
6.5 Metallic structure
This is a diversion-type power station mainly for power generation. Metallic
equipment includes two metallic sluice gates (including the hoisting machine), one
φ300 sand flushing gate valve, one trash rack, 69t penstocks and accessories and 6
expansion joints. The dam is very near to the power house, so the hoisting equipment
is small scaled and seldom used, therefore, manual actuator shall be adopted.
The details of the metallic structure is shown in table 6-4.
6.5.1 Dam and metallic structures at the water intake a. Working gate and the hoisting equipment at the intake
There shall be a plane metallic sluice gate at the intake of the dam with a 2t
manual screw hoist.
Technical properties of the working gate and its hoisting equipment are as
follows:
Dimension of the orifice(width×height): 0.9m×0.9m
Design water head: 2~4m
Orifice type: open
Sluice gate type: metallic gate
Sluice gate dead weight: 0.85t
Orifice number: 1 orifice
Sluice gate number: 1
Hoisting machine: 2t manual screw hoist
b. The trash rack at the intake is arranged with an angle of 70°, as per hydraulic
requirement and shall be cleaned manually.
Main technical properties of the trash rack are as follows:
Dimension of the orifice(width×height): 1.2m×1.8m
Design water head: 2.0m
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Dead weight: 0.4t
Orifice number: 1 orifice
Rack number: 1
Clean method: trash be cleaned by manpower
c. Gate valve at the sand flushing orifice
There shall be one Φ300mm sand flushing orifice in the dam equipped with a
Z541H-100I DN300 gate valve.
6.5.2 Metallic structure for tailwater The overhaul of the power station will not be influenced by normal water level,
so there won’t be a tailwater sluice gate.
6.5.3 Penstocks The penstocks are in total 530m long, with a diameter of 650mm and tube wall
thickness of 6~8mm. Q345C spiral pipes are adopted as steel material and the
penstocks and the supporting structures have a total weight of 69t. (see chapter 5
Design for the details).
6.5.4 Main quantities of metallic structures and equipment Table 6-4 Main quantities table of metallic structures and equipment
No. Item Specification Unit Qty. Remarks
1 Sand flushing gate valve of the dam Z541H-100I DN300 1
2 Embedded parts t 0.12
3 Intake sluice gate 0.9×0.9 m t 0.85
4 Embedded parts t 0.12
5 2t manual hoist set 1
6 Trash rack of the dam 1.2×1.8 m t 0.4
7 Penstocks φ650,δ=6--8mm t 60
8 Expansion joints φ650 pc/t 6/4.5
6.6 Heating ventilation and fire protection
6.6.1 Heating ventilation The power house of this station is of ground type. The main power house is a
one-story building with good ventilation, so the natural ventilation method shall be
adopted. Smoke exhaust measures shall combine with the ventilation system.
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6.6.2 Fire protection 1. General conditions and characteristics of the project
This is a runoff diversion-type power station, focusing on power generation, with
an installed capacity of 200kW. The main power house of the station is a single story
ground building, 12m long, 6.8m wide and 4.5m high. There are 2 turbine generators
with a space of 5.0m. Each unit is equipped with 6 panels beside it at the downstream
side.
The booster station is located opposite to the entrance gate of the power house,
5m long and 5m wide, equipped with one main transformer and a 11kV outgoing line.
2. Design basis of fire protection
(1) Specification on Compiling Preliminary Design Report of Small Hydropower Stations SL179—2011;
(2) Electrical-mechanical Design Code of Hydropower Plant DL/T5186; (3) Code for Fire Protection Design of Hydraulic and Hydroelectric Engineering
SDJ278; (4) Design Code for Heating Ventilation and Air Conditioning of Power House of
Hydropower Station DL/T5165; (5) Fire Protection Specification in Building Design GBJ16; (6)Code of Design for Water Spray Extinguishing Systems GB50219-95; (7)Code for Design of Extinguisher Distribution in Buildings GBJ50140; (8) Code for Design of Automatic Fire Alarm System GB50116; (9) Typical Extinguishing and Protection Regulation of Electrical Equipment
DL5027; (10) Code of Design for Sprinkler Systems GB50084. 3. Design principle
(1) Carry out the principle that “Fire Prevention First, Prevention and Control
Combined” and abide to the specification and relevant policies.
(2) Adopt fire retardant materials for construction and decoration materials, etc.
(3) The design should guarantee that the fire driveway, fireproof space,
emergency exit, emergency smoke exhaust, illumination, etc. meet the requirement of
relevant specification.
(4) Take full advantage of the sufficiency of water source of hydraulic and
hydroelectric project.
(5) Choose qualified products tested by relevant product quality supervision and
inspection departments for firefighting equipment, which should be safe and reliable,
convenient in use, advanced in technology and rational in budget as well.
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(6) Meet the requirement that “relying mainly on self-rescue while seeking for
aid from outside”.
4. Fire protection design
Based on the equipment installed in the buildings of the project and its purpose,
according to the regulations in Code for Fire Protection Design of Hydraulic and
Hydroelectric Engineering SDJ278-90 and Fire Protection Specification in
Building Design GBJ16-87 (2001 version), the fire risk classification and fire
resistance rating of the buildings in the project are listed in table 6-5.
Table 6-5 Main production building fire risk classification and fire resistance rating
table
No. Building/structure name Fire risk classification Fire resistance rating
Remark
1 Main & auxiliary powerhouse and mounting room
4th 2
2 Central control room 3rd 2
3 Main transformer site 3rd 2
4 Distribution device structure 4th 2
Fire protection of buildings
This power station is of diversion-type with buildings located dispersedly, which
mainly consists of the dam, steel pipeline, power house and booster station. With
electromechanical equipment densely placed inside the power house and operation
and management staff concentrated, the plant area shall be the key area for fire
protection in this project.
The permanent buildings of the power station adopt a masonry structure frame,
which caters to the specified fire resistance rating. There are driveways straight to
each building as well.
The space between buildings conforms to the requirement of fire protection
distance and there are evacuation routes inside each building which meet the
requirement of fire safety. The fire protection of the buildings and the
electromechanical equipment shall be arranged under integrated consideration.
Firefighting pipelines shall be buried, with one hydrant set inside the power house.
The fire water shall be fetched from the penstock and the fire protection area shall
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cover the whole building. A suitable number of fire extinguishers shall be equipped as
well. The fire hydrant shall be hung on the wall, 1.2m above ground, equipped with
one 20m long hose and one fire nozzle of 13mm diameter.
Fire protection of electromechanical equipment
1) Fire protection of power house electromechanical equipment
Besides 1 fire hydrant, there shall be 3 portable powder extinguishers, and 3
portable foam extinguishers as well. Openings and holes of switching box,
distribution panel and automatic device panel shall be plugged with fire retardant
materials.
2) Fire protection of booster station and outside of the plant
The booster station is small in area, so the focus of fire protection is the main
transformer loaded with a large quantity of oil. One sand box shall be equipped near
the inlet of the booster station as well.
Fire water supply
The fire water shall be connected to the fire hydrant in the power house after
decompression before the gate valve of the penstock.
Fire electricity
According to the regulations in Code for Fire Protection Design of
Hydraulic and Hydroelectric Engineering (SDJ278-90), emergency illumination
power source shall be connected to the DC system of the power station.
Emergency illumination shall be set in the main power house.
Main firefighting equipment Table 6-6 Main firefighting equipment table
No. Equipment name Main specification & model Unit Qty. Mounting
place 1 Indoor fire hydrant DN50 pc 1 Power house
2 Portable powder extinguisher MF8 pc 3 Power house
3 Portable foam extinguisher MP8 pc 3 Power house
4 Sand box pc 1 Booster station
5 Gas mask pc 2 Power house
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6.7 Lightning protection and earthing
The overvoltage protection of all level voltage distribution equipment shall be
arranged as per the requirements of specifications and regulations, see electric main
wiring diagram for details. A group of zinc oxide arrester is set at the 11kv side to
guarantee that lightning incoming surge will not jeopardize the main transformer,
generators and main electrical equipment under any operation mode.
Install lightning band for direct lightning strike protection of the power house.
The lightning band shall be connected with the column steel structure of the power
house by welding, with earthing bodies arranged along the wall. The earthing
resistance is required not to exceed 10Ω.
The earthing networks in the switching station and power house are formed
jointly by the horizontal earthing trunk and vertical earthing electrodes. Apply -50mm
×5mm galvanized flat steel for earthing trunks, -50mm×5mm galvanized flat steel
for earthing wire and 2.5m long φ50mm×4mm steel pipe for earthing electrodes.
The burial depth of the earthing bodies shall be 0.8m. The earthing resistance of the
main earthing network is required to be smaller than 4Ω, otherwise, remedial
measures, using two earthing bands to connect with the main earthing network of
switching station and power house, shall be taken so as to meet the requirement.
The main earthing network of the power house shall be welded to be like a mesh
with foundation reinforcing steels of 3 meter’s spacing before pouring the turbine
piers. It shall be welded with the tailwater pipe, diversion pipe and the shell of the
turbine. There should be at least two connection points with the two earthing bands in
the cable duct as well. The earthing resistance shall not exceed 4Ω. All of the outside
casing of the electrical equipment and the neutral line of the generator in the power
house shall be connected to the main earthing network.
The outside casing and frame of the electrical equipment in the switching station
should be connected to the earthing network in the switching station.
The equipment earthing and lightning earthing all over the power station should
be mutually independent.
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Chapter7 Project Management
7.1 Introduction
CHIPOTA hydro power station is located on the MULEMBO River where
headman KABAMBA lived, in CHELA TAMBULE village, SERENJE area, Central
Province, Zambia. This is a hydropower station mainly for hydropower generation
with an installed capacity of 200kW. During the construction period, a construction
project department shall be established to perform the function of administration; after
the project is built, it will be transferred to the owner who will perform the permanent
operation and administration functions of the project.
The establishment of CHIPOTA hydro power station’s administrative
organization abides by the following principles:
1. On the premise of ensuring safety in production and operation, constantly
enhance the enterprise’s economic benefits and perfect its management function,
optimize labor combination and use labor scientifically, rationally and economically;
2. The management organization should be simplified, with clear functions and
flexible operation;
3. With a small installed capacity and small number of workers, build only
necessary places for production, office work and resting;
This project is a small (II type) project with a total installed capacity of 200 kW.
According to Rural Hydroelectric Power Plant Manpower and Budget Standards and
the actual condition that the power station adopts automatic operation with less staff
on duty, the personnel quota of this project is 6, of which, 5 for production and 1 for
administration.
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Table 7-1 Departments and personnel quota list
No. Departments Quota (person) Remark
A Management staff 1
B Production staff 5
1 Hydraulic and electromechanical operation 4
2 Overhaul 1
Total 6
7.2 Operation management
7.2.1 Project dispatching operation
This project is of pressure diversion type and the discharge is adjusted
automatically by the speed governor of the turbine. The water overflows the weir crest
during shutdown.
7.2.2 Management and maintenance of the structures
(1) Dam
Since the inlet gate and the flushing gate valve are seldom used, and the flow
velocity is high, the erosion and cavitation of the valve, switching facility, gate valve,
etc. shall be inspected timely each year during the low-water season. If necessary,
overhaul must be arranged.
(2)Water diversion system for power generation and the power house
Apart from the regular maintenance and inspection, inspection and maintenance
at the same time of the overhaul of the units should be arranged on the wetted parts of
penstocks, main power house, etc. Maintenance and regular overhaul and test should
be carried out on all of the electromechanical devices as per relevant regulations and
specifications.
7.2.3Management and maintenance of metallic structures
There are 530m of penstock totaling 69t, 1 sluice gate, 1φ300 sand flushing gate
valve, 1 trash rack and 1 set of gate slots in this power station, bearing the tasks of
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water level control, flood discharge, sediment ejection, water conveyance, protecting
the safe operation of the units, etc. Regular maintenance, rust and corrosion
prevention should be carried out according to the requirements of regulations,
specifications and the design. The corrosion prevention of the penstocks adopts
coating materials of longer protection period and stricter construction technology to
prolong the service life of the penstock. No matter which anti-corrosion measure is
taken, the surface of the steel plate shall be pretreated to remove the rust to meet the
specified cleanliness and roughness before anti-corrosion coating. Trial operation
shall be performed on the discharge equipment before the flood season, so as to
guarantee flexible and reliable operation and timely input.
7.3 Scope of project management and protection
7.3.1 Project management scope
The management scope of this project should include: the key project area and
the production and living area.
The key project area includes: surrounding areas of diversion dam, penstock,
power house, tailrace, booster station, fire water supply facilities, communication
facilities, entrance traffic facilities, etc., 20m away from the outer contour of the
structures.
The production and living area include: permanent buildings in production and
living area.
The land and project occupied land within the management scope are under
unified management of the Management Department, and destruction of grasses and
trees, burial of tombs, erecting of electric poles, stacking of sundries, building of
houses, etc. are forbidden inside.
In case there is any conflict, the local regulations in Zambia shall prevail.
7.3.2 Protection scope
Project protection scope: 200m away from the boundary of the project
management scope.
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Attention should be paid to the water and soil conservation and environment
protection in the above mentioned protection area.
In case there is any conflict, the local regulations in Zambia shall prevail.
7.4 Project management facilities and maintenance of the equipment
7.4.1 Project management facilities
Management facilities in the management area of this project include: diversion
system, power house, communication facilities for electricity dispatching, permanent
buildings in production and living area and traffic roads.
Permanent buildings
Permanent buildings are divided into 2 parts: (1) the production plant and its
auxiliary part and (2) the building for living and welfare. The construction areas of
each part are: 81.6m2for production plant and 20m2for living.
Permanent traffic roads
There are already roads around the project area to link with the outbound traffic.
A simple sand-gravel road needs to be paved into the power house.
Management facilities
Because the installed capacity of this project is very small, there will not be any
special hydrological observation facilities, transportation means will not be purchased
and SPC telephones from the telecom department shall be used for communication.
7.4.2 Maintenance of the equipment
(1) Engineering inspection
The aim of engineering inspection is to avoid accidents, therefore, signs of
abnormality must be caught in time, causes must be analyzed and preventive
measures against accidents must be taken.
Patrol-inspection on hydraulic structures like the dam, penstocks, power house,
etc. should be carried out from the construction period to the operation period,
including daily patrol-inspections, regular patrol-inspections and patrol-inspections
under special circumstances.
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(2) Engineering inspection
Since the project scale is small, only the dam water level will be observed at the
site with a fixed water gauge.
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Chapter 8 Construction organization planning
8.1 Project profile
CHIPOTA hydropower station is located on the MULEMBO River where
headman KABAMBA lived, in CHELA TAMBULE village, SERENJE area, Central
Province, Zambia, with an installed capacity of 200kW.
The main structures of this project include the dam, penstocks, power house,
tailrace, booster station and living area.
(1) Hydrometeorological conditions
Central Province of Zambia has a Savannah climate, featuring a mild climate,
plentiful rainfall and an annual average temperature of 21℃. There are three seasons
all the year round: a dry and cool season from May to August with a temperature of
15~27℃, which is the harvest season for most of the crops; a dry and hot season
from September to November with a temperature of 26~36℃; and a warm and
humid rainy season from December to April, with a lower temperature than the dry
and cool season, which concentrates the precipitation of the whole year. According to
the meteorological data from Hong KongObservatory (1961~1991), the multi-year
average precipitation is 1133.6mm.
(2) Topographic and geologic conditions
The station site is locatedin a platform breaking zone. Under long-term scouring
of the river, the platformbrakes longitudinally along the river course, forming
multi-level waterfalls. The left bank of the river is covered with deep forest on a steep
slope, with a small branch river lying on the left side of the ridge. The right bank of
the river is relatively smooth. There is a flat and vast sloping land with the same
elevation with the last level visible waterfall. The trees grow well but relatively sparse.
The traffic road is on the right side of the river. Above the visible first-cascade
waterfall is flat grassland, which is not eligible for storage capacity.
No defective geological structure is found above the dam site. Part of the
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riverbed rock of this river reach is exposed with a flat grassland on both banks. The
covering is not thick, so the excavation of the dam foundation will be relatively
simple.
Below the dam site, the riverbed ladders are fault scarps, forming cascade
waterfalls. The fault scarps have no signs of further development towards the
upstream. The rock is dark red, and should be karst-rock, a kind of basalt. It is hard.A
plant area lies on the gentle sloping land, with exposed rock. The rock properties are
the same with the riverbed.
(3) External and internal traffic and the supply condition of wind and water
It is 400km from the Capital Lusaka to SERENJE area of Central Province, with
a trunk road equivalent to a secondary asphalt road. It is 20km from the trunk road to
the power station, connected with a flat earth road. Vehicles may be transported after
some slight repair of the earth road. It is 10km from the local community to the
station, linked with a forestry path.
The construction water will be pumped directly from MULEMBO River, while
living water is connected to the community. The dam site and plant site shall be
equipped with two 50kW diesel generators, respectively, to supply construction
electricity.
8.2 Construction diversion
8.2.1 Diversion standards
According to Standard for Classification and Flood Control of Water
Resources and Hydroelectric Project (SL252-2000), this project is a V grade project,
with the dam, power house and diversion structure being in the category of 5th grade.
The flood recurrence interval is 10 years for the earth-rock cofferdam. According to
the project quantities and the construction plan, taking foundation ditch submergence
loss and the impact to the construction into consideration, the diversion adopts a
three-year frequency flood standards of low-water season in May ~August.
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8.2.2 Diversion method
(1) Dam diversion
Diversion method: the construction diversion of the dam adopts a one-step
diversion. It will consist of building an earth cofferdam downstream the little bridge
and diverting water downstream the dam by way of the excavated diversion canal on
the left bank. The cofferdam shall be about 22m long and the diversion canal about
45m long. The height of the cofferdam and the excavation depth of the diversion canal
can be adjusted according to the earthwork equalization of the diversion canal and the
dam.Material for the cofferdam: a combination of bags of clay and earth-stone
material.
(2) Plant area diversion
The plant area is on the right bank of the river. Tailwater from power generation
will be drained to the river through tailrace. The ground of the plant area is relatively
flat, several meters higher than the river course which normally has a low water level.
The construction of the plant is very convenient and there will not be any need for a
cofferdam or construction diversion.
8.3 Selection of the material site and the excavation
8.3.1 Selection of the material site
The layout of the project construction is relatively scattered and there are not
many sand and aggregate materials used in this project. Besides stones, the sand and
aggregate materials needed by the project shall use local materials from site.
8.4 Construction of the project’s main works
The header project consists of structures like the dam, intake sluice gate,etc.
Excavation of the foundation
Drain the waterlogging, seepage water and surface water in the foundation ditch
timely to ensure that the excavation will not be disturbed by water.
Earthwork excavation: drill holes manually, load explosives manually
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usingpneumatic drills, , perform presplitting blasting and stage excavation from top to
bottom and from the bank slope to the riverbed and adopt a millisecond short delay
extrusion step blasting.
Slag discharge: Collect and load the slag manually, discharge the slag with
trolley to the slag stacking site downstream from the dam.
Casting of the rubble concrete
The rubble concrete strength grade is C20. A trolley will be the main method for
the placement of concreteinto the tank and manpower will be applied for embedding
stones. Compact the concrete with aninsertion vibrator and sprinkle water manually
for maintenance. After the casting of rubble concrete coverage, the clearance of the
tank shall follow.
8.5 Construction of the diversion system
The diversion system includes water intake and penstocks.
Engineering of the intake
Earthwork excavation: adopt step excavation from top to the bottom. Drill holes
with pneumatic drills, apply surrounding presplitting blasting.
Masonry: Stones are carried manually. The mortar shall be carried to each
masonry site by manpower. Mortar base slurry method shall be applied in the
constructionand the masonry rises evenly layer by layer.
Concrete construction: concrete shall be delivered by manpower. After placement
of concrete, scrape manually and compact the concrete with insertion vibrator. When
the strength of the lower layer concrete reaches 25kg/c ㎡, prepare for the casting of
the upper layer; meanwhile, chiseling of the concrete surface shall be done before
casting of the concrete.
Reinforcing bar and formengineering: implement according to
Technical Code for Construction of Small Hydropower Station (SL172—96).
Construction of the penstocks
The pipeline is 530m long. Drill holes with pneumatic drills step by step, load
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explosives manually and adopt presplitting blasting. The slags shall be delivered out
by manpower.Those can be utilized shall be used as masonry aggregates for the
anchorage blocks and supporting piers, while the abandoned slags shall be stacked
nearby and used for planting grasses and trees as per water conservancy requirements
after completion of the project.
Processing and mounting of the steel pipe: the steel pipe shall be molded and
processed as per design dimension in the factory, transported to the plant area by a 15t
truck and lifted and welded on site by applying a hoisting machine.
Concrete casting of the anchorage locks and supporting piers: the concrete shall
be mixed in a mixer, delivered to the construction site by trolleys, scraped and
vibrated by manpower.
8.6 Construction of the power house
The power house is a masonry structure frame power house, with 2 horizontal
hydro-generators installed inside.
Foundation excavation
The excavation of the power house foundation takes the elevation of 1371.50m
as the datum plane, above which open excavation shall be applied and below which
trench excavation is used. The excavation of the side slope should abide by the
procedure from top to bottom.
The earthwork excavation adopts step excavation from top to the bottom. Drill
holes with pneumatic drills, load explosives manually and adopt presplitting blasting.
The slags shall be collected by a bulldozer, loaded to a 5t dump truck by a backhoe
excavator and delivered to the area 30m’s range on the right, downstream from the
power house.
Foundation masonry
The power house adopts stone masonry strip foundation. The mortar is mixed in
the mixer and the stones are laid manually, with C20 concrete ground ring-beam on
top.
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Power house
The power house adopts masonry structure. According to the layout of the
generator units and the installation requirement, the space between units shall be 5.0m,
so the dimension of the power house shall be 12×6.8×4.5mand the roof applies light
steel roof truss.
Mounting of the units
In the installation of the units, the maximum hoisted parts in the plant are 2.5t.
Mobile profiled-steel-made supporting frame is adopted, equipped with a manual
hoist with a lifting capacity of 5t.
8.7 Transportation for construction
8.7.1 Selection of transportation means
Based on the actual condition of this project and external traffic, the
electromechanical equipment shall be delivered by sea and road jointly and all of the
construction materials shall be deliveredmainly by road transport.
8.7.2 Outbound transportation
It is 400km from the Capital Lusaka to SERENJE area of Central Province, with
a trunk road equivalent to a secondary asphalt road. It is 20km from the trunk road to
the power station, connected with a flat earth road. Vehicles may be transported after
some slight repair of the earth road. It is 10km from the local community to the
station, linked with a forestry path. In this design, a 650m long 3.5m wide
sand-gravelroad to the power house will be enough to meet the requirement.
8.7.3 Internal transportation
Internal transportation connects the work areas, warehouse and slag stacking site
inside the construction site and all of the production and living areas, which must be
linked to the outbound transportation. The internal transportation of this project is in
good condition and the materials will be delivered by simple road transport.
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8.8 General layout of the construction
8.8.1 The planning and layout principle of the construction
The whole project is located on the right bank, where the bank slope is gentle,
providing many available construction sites. Therefore, the production and living area
during the construction shall make best use of the existing topographic conditions and
be placed on the gentle slopes near the engineering area. The general layout and
planning of the construction shall follow the principles of
construction-need-orientation, overall consideration and planning, compact layout,
less deforestation and convenience for management, living and production. The layout
of each construction facility should make its best to meet the construction requirement
of the main work, avoiding interference and repetitioustransport of the materials. It
will make rational utilization of thetopographic condition and try to realize compact
arrangement so as to reduce preparation work. The division and layout of the sites
should conform to the regulations of the country relating to safety, fire protection,
public health, environment protection, etc.
8.8.2 Construction zoning and layout planning
Sincethe layout of the project is scattered, the construction of the project shall be
carried out by blocks and by zones based on the characteristics of the project,
topographic and traffic conditions and the organization form of construction
management. The whole project can be divided into three parts of construction zones:
dam, penstocks and power house.
Dam construction zone
The dam construction zone mainly focuses on the construction of the diversion
and sand flushing facilities of the dam and the upper part of the penstock. The planned
area of temporary buildings in this construction zone is 100m2, occupying a floor area
of 130m2, which is located near the project zone.
Penstock construction zone
The penstock construction zone contains the construction of penstocks. The
living and production facilities are located on the gentle slope near the curve of the
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penstock. The area ofall of the temporary buildings in this construction zone is
planned to be 300m2, occupying afloor area of 450m2, which is located on the right
sides of the penstock.
Power house construction zone
The construction of the power house includes the construction of power house,
tailrace, booster station and the lower part of the penstock. The total area of various
temporary buildings is planned to be 400m2, occupying a floor area of 500m2, which
is located around the plant area. See table 8-1 for the areas of permanent and
temporary housing in each construction zone.
Housing for living and officeswill be built on the open land near the power house.
Six integrated board houses with a dimension of 6m×2.4m will be adopted.
Table 8-1 Area list for living and administration camps and temporary warehouses
8.8.3 Waste slags site
The site will make best use of the rock slags produced in the excavation of the
buildings’ foundations. Those that cannot be utilized shall be delivered to the waste
slags site. Part of the slags excavated from the plant area will be used as engineering
material, while the residue backfills the low-lying part by leveling the ground. No
extra slag site shall be arranged.
No. Items Building area(m2
)Floor area(m2
) Remark
1 Dam construction zone Temporary building 100 130 Temporary
land use
2 Penstock construction zone
Temporary building 300 450
Temporary land use
3 Power house construction zone
Temporary building 400 500
Temporary land use
4 Housing for living and offices 86.4 120 Temporary land use
Temporary land use in total 886.4 1200
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8.9 General construction progress
8.9.1 Implementation basis and principle
The construction progress of this project shall be controlled as per the average
level of the power stations of the same type in China. According to Code for
Construction Organization Plan of Building Engineering GBT50502-2009,as based
on the actual situation of the project, the construction progress shall be divided into
four stages: project starting period, project preparation period, main works
construction period and project completion period.
8.9.2 General construction progress
(1) Project starting period
The proprietor shall take charge to start the work of external traffic, construction
electricity, communication, landexpropriation, public bidding, etc. with a planned
time table of 2 months.
(2) Project preparation
Main jobs that should be done during this period are: ground leveling, internal
traffic, diversion engineering, building of temporary housing and construction plant,
etc., with a planned time table of 1 month.
(3) Main works construction period
This period starts from the beginning of the project to the time when all of the
units generate power, with a planned construction period of 11 months.
(4) Project completion period
This period starts from the time when all of the units generate power to the time
when the project is completed and accepted, with a planned time table of 1 month.
8.10 Main construction machinery
See table 8-2 for the main mechanical equipment needed in this project.
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Table 8-2 Main mechanical construction equipment table
No. Equipment name Specification Unit Qty. Remark
1 Pneumatic drill YT-24 set 5
2 Down-the-hole drill YQ150A set 2
3 Air compressor 4L-20/8 set 2
4 Water pump 3B33 set 2
2B31A set 2
5 Backhoe WY40-HZ set 1
6 Crawler bulldozer TS-140 set 1
7 Truck crane QC20 set 1
8 Excavator 200 set 2
9 Concrete mixer 0.4 m³ set 3
10 Diesel generator 50kW set 2
11 Lithotripter set 1
12 Sand producing system set 1
13 Transport hopper set 10
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Chapter 9 Labor Safety and Industrial Sanitation
9.1 Design Basis
9.1.1 Provisions of the national and local administration Document of the Ministry of Power Industry, China Renewable Energy
Engineering Institute---Notice on Adding the ‘Labour Safety and Industrial
Sanitation’ in the Compilation of a Feasibility Report (S.D.G.S [1997] No.0014).
9.1.2 Technical specifications, procedures and standards
1) Code for design of occupational safety and health of hydropower projects
(NB35074-2015)
2) Code of safety operation in power engineering construction(Part of
substation)(DL5009.3-2013)
3) Code for fire projection design of hydropower projects (GB50872-2014)
4)Technical code of construction and installation for hydroelectric and hydraulic
engineering(SD267-88)
9.2 Project Overview
9.2.1 Project location
CHIPOTA hydropower station is located on the MULEMBO River (where the
tribe chief KABAMBA resides), CHELA TAMBULE village, SERENJE region of the
central province of Zambia. It is 400 km away from the Capital Lusaka, located at
latitude 13°13' 4.8" S and longitude 30°25' 52.24" E.
9.2.2 Project layout
The powerhouse is a diversion-type ground plant. The powerhouse and booster
station are located at the gentle slope on the right bank at the bottom of the
fourth-cascade waterfall. The newly built 650m permanent road makes outgoing
traffic relatively convenient. The management room is located close to the hillside
beside the incoming road. Layout of the whole powerhouse area is relatively simple.
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9.2.3 Characteristics of natural conditions
The central province of Zambia has a mild tropical savanna climate, abundant
rainfall, and an average annual temperature of 21℃. It has three seasons throughout
the year: from May to August, it is the dry cool season, with the temperature between
15 ~ 27℃, a harvest season for most crops; from September to November it is the dry
hot season, with the temperature between 26 ~ 36℃; and from December to April, it is
the warm wet season, with the temperature slightly lower than the dry cool season,
with the annual rainfall concentrated in this season. According to the meteorological
data of the Hong Kong Observatory (1961~1991 year), the average annual rainfall is
1133.6mm.
9.2.4 Project benefit and major hazards
The installed capacity of the hydropower station is 200kW, and the long term
average annual power output is 1,355,300kWh.
After the project is completed, major hazards consist of the following:
1) Combustible substances in the powerhouse may cause fire;
2) A large number of high and low voltage electrical equipment in the
powerhouse may cause personnel injury in the case faulty handling or accident;
3) The hydro- turbine generator, air compressor and other equipment in the
powerhouse will generate excessive noise during operation, which may cause hearing
loss, as well as affect the health of the managing personnel;
4) The wires and cables in the powerhouse will produce poisonous gas if caught
fire, which will affect the personnel’s health and cause poisoning.
9.3 General Layout of the Project
This project is a diversion-type ground powerhouse, with the main powerhouse
being only one story and 12m long by 6.8m wide. It is parallel to the riverbed, with
the mounting site and the entrance gate on the right. The main powerhouse will be
equipped with two sets of 100kW inclined type turbine-generator units, with a spacing
of 5m between them.
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The power station has a set fire extinguishing system with a water supply coming
from the pipe of the circulating pump inside the powerhouse. A fire hydrant and other
fire extinguishing equipment should be installed in the main powerhouse and booster
station to meet the fire extinguishing requirements.
The engineering area should have a reliable solution of electrical storm
protection. A lightning belt should be installed on the roof, connected to the column of
the steel structure of the power house by welding, with a grounding device arranged
along the wall.
The CHIPOTA hydropower station is located in a mild climate, and the main
powerhouse will adopt a natural ventilation system.
The booster station is located at the opposite side of the powerhouse entrance
gate, adjacent to the powerhouse and is facilitated for electrical connection. The main
transformer is arranged inside the booster station, which is facilitated for operation
and maintenance of the main transformer. 1.7m high fences should be installed around
the perimeter of booster station in order to guarantee the safety of all personnel and
prevent any risk of electric shock. A clear path of at least2m wide between any high
voltage electrical equipment and the fence should be maintained in order to guarantee
the safety of all personnel.
The simple design of the powerhouse allows for natural light to enter the
structure during the day. It is also fitted with artificial lighting to light the facility
during the night. The main powerhouse has been equipped with emergency
illumination to ensure lighting is provided during any electricity outages.
Regularl inspections are required for all electrical equipment and tools in order to
prevent any electrical damage and ensure personnel safety,
Mechanical equipment inside the powerhouse must meet the requirements and
specifications of any proper safety distance. The safety requirements of the protective
enclosure and the protective shield of mechanical equipment should be in accordance
within the provisions of the relevant standards. All mechanical equipment shall meet
the qualifications and standards in regards to reliability and safety performance.
When the inlet and–outlet lines of the booster station are put into operation, any
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and all safety requirements of construction should be met.
9.4 Labor Safety
Labor safety is the guarantee of normal operation of the hydropower station,
which includes fire prevention, prevention of explosion, electrical damage prevention,
mechanical damage prevention, dropping damage prevention, flood prevention and
drowning prevention in the main powerhouse and booster station.
Due to the presence of a large number of electrical equipment inside the plant,
the inspection personnel and maintenance personnel are at risk of electrical injury or
accidental electric shock caused by improper handling. The main high-voltage
equipment is located in the booster station, where improper handling or carelessness
may cause personal injury. Qil tanks, cables and other flammable material in the plant
increase the risk of fire and damage to the electrical equipment andthe plant.
Malfunction of the pressure relief devices, such as the compressed air tank, oil
pressure device in the speed regulator, main transformer and other pressure vessels
increase the risk explosion.
9.4.1 Prevention of Fire and Explosion
Heating using open fire is strictly prohibited in all workplaces of the hydropower
station. A reliable electrical storm protection and grounding system should be installed
in the plant, booster station and other structures.
Besides 1 fire hydrant, there shall also be 3 portable dry powder extinguishers
and 3 portable foam extinguishers. 1 sand box shall also be equipped near the entry of
the booster station. A water supply shall be connected to the fire hydrant in the plant
after decompression, in front of the gate valve of the penstock.
9.4.2 Electrical damage prevention
The main transformer of this project shall be installed outside. 1.7m high fences
should be installed around the perimeter of the booster station in order to guarantee
the safety of all personnel and prevent any risk of electric shock. The fence door shall
be installed with a lock, as well as a yellow warning sign: "Beware of Electric Shock".
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A clear path of at least 2m wide between any high voltage electrical equipment and
the fence should be maintained.It is strictly prohibited to set up a communication wire
line, broadcasting line and low voltage line on the high-voltage equipment framework.
There is also a large number of low-voltage equipment in the plant that may increase
the risk of injury and should be operated with caution in order to decrease the risk of
injury. In the transition periodfrom the initial stage of operation to the normal stage of
operation, protective railings and safety signs should be installed around the
distribution devices using electricty. Operating safety distance of operating personnel:
a distance of at least 0.6m wide should be maintained between live distribution units
with a voltage below 35kV and the railing. The voltage of working lights used by the staff are required to meet provisions of
the GB/T3805-93 Extra-low Voltage (LEV) Limit Value. Lighting fixtures must be
installed at least 2.4m above the floor., If the voltage of the fixture exceeds provision
of the Extra-low Voltage (LEV) Limit Value, effective measures should be taken in
order to prevent electric shock.
9.4.3 Mechanical damage prevention and crash damage prevention
Set slots to fix the temporary protective railings at the holes and pits that may
form a falling height of more than 2m during maintenance.
9.4.4 Flood prevention and drowning prevention
Set reliable drainage facilities on the ground floor of the main powerhouse and
the booster station. The outlet elevation of all drains, pipes and channels going to the
outside of the building should be higher than the downstream flood level of the
powerhouse. The water pump drainage pipeline of the machinery drainage system
should be set with a check valve.
9.5 Industrial Sanitation
Industrial sanitation includes noise and vibration proofing, temperature and
humidity control, lighting and illumination, dust proofing, antifouling, anti-corrosion,
anti-toxicity and anti electromagnetic radiation, etc.
Water turbines, generators and other equipment may produce noise which may
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greatly harm the hearing function of the staff and may cause hearing loss. For
long-term staff that are working in the powerhouse, the high humidity inside may
cause arthritis.
When the water turbine generator, transformer, circuit breaker and other
equipment are in operation, they will produce excessive noise. When the circuit
breaker trips, the noise may exceed 115dB, which can seriously impact one’s physical
and mental health: hearing loss, and a variety of diseases, such as heart disease,
hypertension, neurosis, etc. In high temperature and humidity work environments,
especially where the relative humidity is higher than 75% and the temperature is
higher than 35℃ , it is easy to develop symptoms of rheumatism arthritis.
Flammable and explosive materials in the powerhouse will produce low fluorine
compounds, noxious smoke and other harmful substances in the course of operation.
There is an increased risk of health issues if there is poor ventilation. Personnel
exposed to microwave radiation may develop the following health issues:
dysfunction of the nervous system, blood circulation system, reproductive system,
blood micro elements, physiological metabolism, etc. All safety precautions should be
considered and necessary protective health gear should be worn.
9.5.1 Noise proof and vibration proof
Reasonably arrange the noise sources to reduce the harm of noise to human ears.
Arrange any loud equipment in the duty rooms far away from the powerhouse. Set
partitions between each duty room and use an indoor air conditioner with silence
design in the control room and main offices. The personnel on duty should enter the
powerhouse with ear protection to reduce the harm of industrial noise.
When choosing a water turbine generator type, the manufacturer is required to
choose and install equipment with a noise level not exceeding 85dB (A), so as to
reduce the noise level of the working environment.
9.5.2 Temperature and humidity control
This plant has a one-story powerhouse with good ventilation. But, it is also
necessary to open the windows from time to time for ventilation to ensure proper
temperature and humidity and health of the staff in the workplace. In the general duty
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places and unattended places, do a good job of mechanical ventilation to promote the
lifespan of the equipment and health of the inspecting personnel.
9.5.3 Lighting and illumination
The project has been designed to make full use of natural light in the day, and at
night with artificial lighting. All of the workplaces should be installed with
illuminators according to the requirements. The main powerhouse has been equipped
with emergency illumination to ensure the lighting needs in case of accidents.
9.5.4 Dust proof, antifouling, anti-corrosion and antitoxin
When the mechanical braking device is put into operation, it will produce dust,
and part of the braking devices that contain asbestos products may decompose and
produce harmful substances during the braking process. Therefore, the brake material
is preferred to use mechanical brake parts with good wear resistance and less dust.
Any industrial waste oil shall not be discharged into the watercourse and shall be
delivered to the designated location after treatment.
The storage battery in the DC system is a fixed lead-acid maintenance free
battery, which will emit a small amount of gas during operation. As long as the
ventilation is strengthened, there will be no need for special treatment.
9.5.5 Anti electromagnetic radiation
For staff exposed to microwave radiation, they should reduce the harm of
electromagnetic radiation to the human body mainly through the control of operating
time. When the electric field intensity is 111KV/m, 15KV/m and 20KV/m, the
operation time should be respectively limited to 3h, 1.5h and 10min.
9.6 Safety and Health Facilities
In regards to the safety and health agency, the safety engineers shall be
responsible for carrying out safety and health publicity and education, engineering
monitoring, safety equipment repair and maintenance to ensure the normal operation
of electrical equipment. Safety engineers are required to have a rich experience of
project management and work safety; be familiar with laws and regulations,
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specifications and standards relevant to safety and health aspects; be familiar with the
performance and usage of various monitoring equipment; can timely discover and
deal with security risks; and can take emergency rescue measures when an accident
happens.
A safety and health agency needs to be equipped with anacoustimeter,
thermometer, hygrometer, multimeter and necessary safety publicizing equipment.
9.7 Safety Precautions
9.7.1 Labor safety precautions
In accordance with the requirements of GB2894 Safety Signs, safety signs
should be made and hung up in a conspicuous location. Safety signs include No
Crossing, No fire, Electric Shock, Beware of mechanical injury, Watch your step,
and Ear defenders.The location of firefighting equipment and safe evacuation exit
signs shall also be clearly marked.
The safety engineers should do a good job of safety publicity, standardize the
safety operation of the staff and regularly maintain the safety facilities to ensure the
safety of the staff. Emergency measures should be taken once a safety accident
occurs.
9.7.2 Emergency measures
When any equipment breaks down, the main equipment will be under protection
of automatic protection device. Parts of equipment without automatic protection
device will require emergency repair or be replaced by spare equipment to ensure the
safety of system operation.
In case of personal electrical injury, poisoning, mechanical or dropping damages
or other personal injuries, emergency measures should be taken to treat the wounded.
If the personnel experiences electrical injury, we should first switch off the electricity
and then treat the injured. In case of poisoning, the poisoned should be immediately
carried out of the room and receive treatment from the medical staff. For patients who
go into shock, they should immediately receive artificial respiration and be helped to
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recover respiratory function with the greatest efforts. In case of fire, firefighters and
security personnel should immediately organize an emergency evacuation from the
emergency exit and immediately organize fire fighting. For all of the wounded
personnel, paramedics should organize a timely rescue, and if necessary, contact the
hospital for additional help.
In case of over-level flood, the management and the relevant local departments
will organize flood-fighting and emergency rescues to ensure the safety of the
facilities.
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Chapter 10 Inundation Treatment and Land Requisition
10.1 Overview
The CHIPOTA hydropower station is a diversion-type hydropower station with
an installed capacity of 2×100kW. The main project consists of the dam, penstocks,
plant, tailrace and booster station, etc. The hydropower station is primarily aimed for
power generation. The maximum height of its water-retaining dam is 3.5m and the
normal water level is 1421.50m.
10.2 Design Basis
10.2.1 Laws and Regulations, Specifications and Codes (1) The Law of Land Administration of the People's Republic of China
(1999.1.1);
(2) Forest Law of the People's Republic of China (1998.7.1);
(3) Notice on the Relevant Issues Concerning Construction Land of Water
Conservancy and Hydropower Projects (G.T.Z.F [2001] No. 355);
(4) Interim Measures on collection and usage of the Fees for Forest Vegetation
Regeneration(C.Z [2002] No. 73);
(5) Specifications on land requisition and resettlement design for Construction of
Water Resources and Hydropower Projects (SL290-2009);
(6) Compilation and Calculation Standard of Design Budget Estimation for
Hydropower Project (2002 Edition);
(7) Design Code for Small Hydropower Station (GB50071 - 2014);
(8) Other relevant laws, regulations, policies and professional technical
specifications.
This design shall be temporarily implemented in accordance with the existing
laws and provisions established by China, the inundation and land requisition
operations shall be undertaken by the owner in accordance with the provisions
established in Zambia.
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10.2.2 Design data
(1) The measured topographic map (1:1000);
(2) Construction layout of CHIPOTA hydropower station;
(3) Other relevant data.
10.3 Inundation Treatment
The diversion dam of the CHIPOTA hydropower station is very low, and below
the normal water level is the natural river course. There is no loss without farmland
and houses inundated.
According to the geological survey of the dam site, both sides of the dam show
high level of stability. Therefore, it will not cause bank landslide once completed.
10.4 Land Requisition of the Project
Land requisition includes both permanent as well as temporary requisitions in
accordance with the project area, construction area, living area and plant. The
construction area comprises construction campsites, construction sites, and the
abandoned slags field.
1) Permanent land requisition
According to the project layout and construction design, the permanent land
requisition of the CHIPOTA hydropower station is about 4,500m2, which principally
comprises the plant, booster station, diversion power system and entrance road.
2) Temporarily land requisition
The temporarily land requisition of the hydropower station is about 2,000m2,
mainly comprising the abandoned slags field and constructor area.
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Chapter 11 Water and Soil Conservation
11.1 Principles and Standards
The water and soil conservation measures should be a part of the overall design
of the project, and should be designed, constructed and operated observing the same
standards as the main project.
The standards observed for water and soil conservation measures are the
following: (1) Technical Regulation on Water and Soil Conservation of Development and
Construction Projects (GB50433 - 2008);
(2) Standards for Classification and Gradation of Soil Erosion (SL190 - 2007);
(3) Comprehensive control of Water and Soil Conservation—General rule of
planning (GB/T15772 - 2008);
(4) Comprehensive control of Water and Soil conservation—Regulation of
acceptance (GB/T15773 - 2008);
(5) Comprehensive control of Water and Soil Conservation—Method of benefit
calculation (GB/T15774 - 2008);
(6) Technical specification for Comprehensive control of Soil and Water
Conservation - Technique for erosion control of gullies (GB/T16453 - 2008);
(7) Cost constituents and Calculation standards for Design Budget Estimate of
Water Conservancy and Hydropower Project.
This design shall temporarily be implemented in accordance with the existing
laws and provisions of China; the owner shall complete procedures pursuant to
provisions established by Zambia.
11.2 Project and Overview of Project Area
11.2.1 Overview
CHIPOTA hydropower station is mainly aimed for power generation. It presents
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a rubble concrete gravity dam, with a maximum height of 3.5m, a design installed
capacity of 2×100kW and an average annual output of 1,355,300 kWh. The project
consists of the dam, penstocks, plant, tailrace and booster station. The pipelines are
arranged on the right bank of the river course and laid along the hillside. The booster
station is arranged on the upstream side of the plant. The total project duration is 13
months, with its main part requiring 10 months out of the overall duration.
11.2.2 Status and Prevention of soil erosion
CHIPOTA hydropower station is located on the MULEMBO River (where the
tribe chief KABAMBA resides), CHELA TAMBULE village, in the SERENJE region
of the central province of Zambia. The site is located in a platform fracture zone.
Based on the soil erosion module diagram of similar areas, we have analyzed the
water and soil erosion conditions combined with spot-surveying. We conclude that the
main status is surface erosion, with a loss intensity varying from slight degree to
moderate degree.
11.3 Forecast of Water and Soil Erosion
11.3.1 Forecasting Basis
The erosion of this construction project includes any and all excavation exposed
surface, abandoned slags surface and side slope, resulting from the lack of observance
of protective measures. We will analyze and forecast the possible water and soil
erosion and associated hazards.
11.3.2 Forecasting Time Period
The forecast is divided into two periods: the construction period and the
operation period. The operation period is mainly to generate electricity without
erosion. Therefore, the erosion mainly occurs in the construction period and the initial
operation period. The forecast period of water and soil erosion will be determined
according to the project construction period (12 months) and the natural enclosure
restoration time. For the purposes of this project, the period will be 1 (one) year.
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11.3.3 Content and Method of Forecast
The content for water and soil erosion forecast mainly includes:
(1) Forecast of original landform and vegetation damage;
(2) Forecast of amount of abandoned slags;
(3) Forecast of the possibly caused water and soil erosion area and the total
amount of newly increased erosion;
(4) Forecast of damage from water and soil erosion.
There are many methods applied for the purpose of water and soil erosion
forecasts. Based on the actual condition of the project and the maneuverability of each
method, the following forecast methods may be applied in different areas: the natural
slope ratio accumulation method for the abandoned slags filed and the analogue
method for each prevention and control subarea.
11.3.4 Forecast results and comprehensive analysis
(1) Disturbance of the original landform, damaged land and vegetation
conditions
Disturbance ground area of the CHIPOTA hydropower station mainly refers to
the construction requisition area and directly affected area, including the main project
area, stone materials field, abandoned materials field, temporary construction facilities
(construction warehouse, temporary stockyards, construction road etc.). Details are
shown in table 11-1:
Table 11-1 Disturbance area, damaged land and vegetation area (unit: m2)
Category No. Project name Total
Project
construction
area
1 Main project area 1863
2 Living area 140
3 Permanent road 3750
4 Soil and stone materials
f ield 150
5 Abandoned slags f ield 100
6 Temporary construction land 300
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Total 6303
(2) Forecast of total amount of newly increased water and soil erosion
Possible newly increased erosion area of the project mainly includes the
excavation surface area, living area, area of the permanent road, the exploiting
stripping area of the material field, abandoned slags filed and temporarily land area,
which account for a total area of 6500m2.
Based on the field survey, the project adopted a natural slope ratio accumulation
method and an analogue method to forecast the amount of water and soil erosion in
the construction period and the affecting period. The total amount of newly increased
erosion of the project is expected to be 60t.
(3) Forecast of damage from water and soil erosion
The project has disturbed the ground area in the construction process and caused
the formation of an amount of abandoned slags. Provided proper prevention and
control measures are not taken, an area of 6500m2 will face soil erosion of up to 60t.
Therefore, we must pay attention to the water and soil conservation requirements of
the project, keep the erosion under effective control and reduce its levels to the
minimum extent.
11.4 Prevention and Control Scheme for Water and Soil Erosion
11.4.1 Prevention and control principle and objective
The purpose is to restore or rebuild the damaged forest land and other water and
soil conservation facilities as soon as possible, protect the ecological environment,
reduce erosion to allow for the restoration rate of disturbed land up above 98%.
In the case of land that has observed a reduction or loss in its water and soil
conservation function as a result of the effect of excavation, filling and other activities
in the construction process, we should timely take engineering and vegetation
measures to restore or improve its water conservation functions, allowing for the
erosion control treatment to reach a level higher than 91%. We should also control the
newly increased erosion and insure the control rate is above 98.6%.
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The abandoned slags should be located centrally and both engineering and
vegetation measures should be taken to allow for the protection rate of abandoned
slags to reach 95%, thus allowing for a reduction and control of the sediment entering
the river.
For permanently and temporarily requisition land, measures such as recultivation,
planting, as well as other afforesting measures should be taken in order to increase the
vegetation restoration rate up to 86%, and the vegetation coverage rate up to 71%.
11.4.2 Prevention and control responsibility
The water and soil erosion prevention and control scheme include the following
two aspects: (1) The key administration area of the construction refers to the main water
and soil conservation damage area which includes the dam, penstocks,
plant and the construction road as well as the renting land during the
construction period. Additionally, it should also include land aimed at
temporarily construction work.
(2) The area damaged by water and soil erosion as a result of construction
activities is a directly affected zone, and responsibility is to be assumed
by the constructor.
11.5 Measures of Water and Soil Conservation
11.5.1 Overall layout of water and soil conservation measures
Taking the abandoned soil (stone) field and the main project prevention area as
the key flood control area, take systematic prevention and control measures and form
a feasible erosion prevention and control system. The water and soil conservation
scheme of the project area should be mainly based on the biological measures and
should be supported by the engineering measures. Biological measures are mainly the
afforestation of the main project area and the affected area, foresting of the abandoned
slags field and material field. There are only a few areas in need of engineering
measures, mainly in the form of supplementation.
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11.5.2 Layout of prevention and control engineering measures
The construction technique of CHIPOTA hydropower station is not complicated
and there will not be many types of disturbance. Although quantity of abandoned soil
and stones and slags is small, the construction will cause new water and soil erosion.
Therefore, the water and soil conservation facilities must be implemented
simultaneously with the main project to provide a timely control of the erosion. The
residue blocking facilities must be completed prior to the main project so as to avoid
erosion.
(1) Key project area (penstocks, plant)
Key buildings of the CHIPOTA hydropower station include the dam, penstocks,
plant, among others.
For the excavation area, we can reclaim the forestry land, create water
conservation forest and plant grass, conduct a rational allocation of trees, shrubs and
grass; restore vegetation as soon as possible to conserve water and soil. For the plant
area, we can make an overall garden landscape design and improve traffic.
(2) Abandoned soil (stone) field
We should combine engineering measures and vegetation measures. Make the
abandoned soil (stone) site a retaining engineering, so as to play a important role of
the retaining wall in water and soil conservation.
11.5.3 Water and soil erosion monitoring
Newly increased water and soil erosion of the project is mainly caused by the
abandoned slags, so the focus of the water and soil monitoring is the abandoned slags
area. The key point is to monitor the quantity and damages of water and soil erosion,
as well as the engineering benefit of water and soil conservation.
11.5.4 Remedial measures for water and soil erosion
If water and soil erosion occurred, we should set debris dams in the downstream
river course to block the upstream erosion sediment and timely remove them to the
abandoned slags field on gentle land.
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11.6 Construction Organization Design and Budget Estimate
11.6.1 Construction organization design
(1) Organization and management measures
The owner will be responsible for the organization and implementation of the
water and soil conservation scheme, coordination with the main project and
delegation of supervision with qualified supervisory company. The water
administrative department will be in charge of the supervision and inspection of the
implementation of the water and soil conservation scheme and acceptance of relevant
facilities.
(2) Technical assurance measures
This scheme should be designed and taken as the basis for construction and
acceptance after validation by the water administrative department.
(3) Funding sources and arrangements
Required funds of the water and soil conservation project will be included in the
total project investment plan and be raised by the owner. The aforementioned funds
will be used for its specific purpose only.
11.6.2 Budget estimate for water and soil conservation
The water and soil conservation project of the CHIPOTA hydropower station is a
supporting project of the main project, which mainly includes the design for water and
soil conservation, the soil and stone materials field, the abandoned materials field and
the temporary construction land. The remediation content is slag blocking, sod
revetment, drainage and afforesting. The total investment of the water and soil
conservation is 10,600 US Dollars.
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Chapter 12 Environmental Impact Assessment
12.1 Regional Environmental Conditions of the Project
12.1.1 Engineering overview
CHIPOTA hydropower station consists of the dam, diversion pipelines,
powerhouse and booster station, etc. The power station has an installed capacity of
2×100KW, a design head of 45.38m, a design discharge of 0.68m3/s, an annual power
generation capacity of 1,355,300 kWh, and 6777 installed utilization hours.
12.1.2 Natural environmental conditions
Engineering geology
The site is located in a platform fracture zone. Through long-term erosion of the
river, the platform broke into sections lengthwise along the river and formed
multiple-cascade waterfalls. On the left bank of the river there are dense forest and
steep mountains, and on the left of the ridge there is another small tributary. On the
right side of the river there are relatively flat mountains; at the elevation position
where the final-cascade waterfall is visible there is a relatively flat and open sloping
field, where the trees are flourishing but remain relatively sparse. Traffic road is
located on the right side of the river. Above the visible first-cascade there is flat
grassland, which is not eligible for storage capacity.
Hydrology and weather
The central province of Zambia has a mild tropical savanna climate, abundant
rainfall, and an average annual temperature of 21℃. It has three seasons throughout
the year: from May to August it is the dry cool season, with temperatures between 15
~ 27℃, a harvest season for most crops; September to November is the dry hot season,
with temperatures between 26 ~ 36℃. December to April is the warm wet season,
with temperatures slightly lower than those observed in the dry cool season; the
annual rainfall is concentrated in this season. According to the meteorological data of
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Hong Kong Observatory (1961~1991 year), the average annual rainfall is 1133.6mm.
12.2 Preliminary Environmental Impact Assessment
The construction of the power station has little influence on the natural
environment. The project is located in an area of no farmland submersion or cultural
relic protection, and the project covers an area of general forestland. Its adverse
effects are mainly observed in the requisition of the construction land in the social
environmental aspect. The owner of the project is responsible for the treatment of the
requisited construction land, and implements negotiable compensation for the project
land acquisition according to relevant provisions and the current reality. The problem
of project land occupation can be properly solved.
From an environmental perspective, there is no major environmental issue to
obstruct the project, making the development of the CHIPOTA hydropower station
project feasible.
12.3 Design Basis and Standards
Design basis (1) Environmental Quality Standard of Surface Water (GHZB1-1999);
(2) Ambient Air Quality Standard (GB3095-96);
(3) Noise Limit for Construction Field (GB12523-90);
(4) Technical Specification for Comprehensive Treatment of Water and Soil
Conservation.
Design Standards (1) GHZB1-1999 Environmental Quality Standard for Surface Water;
(2) GB5749-1992 Sanitary Standard for Drinking Water;
(3) GB5084-1992 Farm Irrigation Water Quality Standard;
(4) GB8978-1996 Comprehensive Sewage Discharge Standard;
(5) GB3095-1996 Atmospheric Environmental Quality Standard.
The information contained in this design shall abide by the existing laws and
provisions established by China. Provided any corresponding regulations from
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Zambia were applicable, the Owner shall complete procedures pursuant to the
provisions established in Zambia.
12.4 Design of Environmental Protection Measures
12.4.1 Ecological environmental protection measures
(1) To strengthen the work of protection and recovery of forest and grass
upstream.
(2) To strengthen the construction supervision and environmental protection
education. Legal and environmental protection education should be carried out for the
benefit of construction personnel as well as for the awareness promotion of relevant
laws and regulations of the state and the identification of the national protected wild
animals in the construction area. It is required to have the staff understand the
significance and effect of wild animal protection and understand that the protection of
wildlife is the duty of every citizen.
12.4.2 Treatment measures for the construction and production of wastewater and
domestic sewage
In order to protect the water quality of the river, engineering treatment measures
should be taken to manage the construction wastewater.
(1) Wastewater treatment scheme for the sand and stone material processing
system.
As the artificial sand and stone material processing system consumes large
amounts of water, it is suggested to set a wastewater treatment circulatory system to
reduce the discharge of wastewater. The wastewater pollutants produced by the sand
and stone material processing system are mainly sediment suspended solids. In a
wastewater treatment project, the process for reducing the suspended solids content is
relatively simple, reaching the discharge requirements simply through sand setting
and a sedimentation treatment. Add coagulant in the treatment process to accelerate
sedimentation.
(2) Waste water treatment scheme for concrete mixing system
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The concrete mixing system itself does not discharge production wastewater, but
produces wastewater in the flushing process. The concentration of suspended solids
and PH value of the wastewater is high, allowing for a centralized treatment.
According to the requirements of the comprehensive wastewater discharge standard
established by the national and local environmental protection department, the
concentration of suspended solids of the treated wastewater should be lower than
70mg/L, with a PH value between6-9. In a wastewater treatment project, the process
applied for the reduction of the suspended solids content and the PH value is
relatively simple, reaching the discharge requirements simply though sedimentation
and the addition of acidoid.
(3) Treatment measures for sporadic decentralized wastewater
In the construction process, when it is difficult to provide centralized treatment
to some flowing, decentralized wastewater sources, we should try to use the terrain
conditions to dig drainage ditches and set sumps to allow the wastewater to receive
natural sedimentation before entering the river to reduce sediment content.
(4) Treatment measures for the construction of domestic sewage
The construction of domestic sewage mainly contains suspended solids, BOD,
COD, nitrogen, phosphorus and other nutrients, which do not reach comprehensive
sewage discharge standards, and can be discharged after being treated through a
small-sized integrated wastewater treatment equipment. The medical sewage of the
construction medical station can be discharged following the disinfection treatment.
In the construction of the living area, public toilets with septic tank should be built.
12.4.3 Treatment measures in the construction of a waste residue
In order to effectively prevent rainwater erosion from causing water and soil loss
and the waste residue collapse, such waste residue field should provide a slope
reinforcement treatment and build a retaining wall. In addition, in order to restore the
vegetation landscape in the construction area, we should timely provide new soil on
the waste residue field after the completion of the construction work, and plant shrubs,
trees with a well-developed root system and a strong drought resistance capability.
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12.4.4 Protective measures against dust and noise
In the dry season, water the construction road to reduce the levels of dust; the
construction excavation process includes a wet dust removal operation; use a sealed
cement injection pump for loading and unloading cement in the transportation process;
concrete mixing equipment should be equipped with dust remover. The construction
personnel working near the noise source should wear protective anti-noise earplugs
and earmuffs.
12.4.5 Greening measures in the construction area
The permanent living area and office area should adopt point-line-surface
combined small garden type with green lawns, hedges, flowers, fruit trees and some
ornamental plants to create a beautiful work and living environment for the power
station workers.
We should fully carry on the site remediation and greening work for the
temporary construction land (including the slags field and each production area) after
the completion of the construction work. The original cultivated land should be
restored according to relevant provisions of the state, and the rest of the temporarily
occupied land should be greened to the furthest extent possible.
12.4.6 Health protection measures
In view of common infectious diseases and various infectious diseases that may
be caused by the project construction in the project area, from the three links, namely,
the source of infection, the transmission way and the susceptible population, the
following comprehensive protection measures should be taken:
(1) The construction unit shall provide necessary medical equipment and
prevention and treatment medicine against infectious diseases in the construction site,
establish and perfect the disinfection and isolation system, improve the disinfection
measures and prevent iatrogenic infection.
(2) We should spread prevention knowledge of infectious diseases among the
engineering staff, mobilize people to carry out regular mosquito, fly and rodent
eradication and other patriotic health campaign to improve environmental hygiene and
strengthen personal hygiene protection.
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(3) The construction area should adopt a centralized water supply system, and
the water quality and hygiene requirements should meet the national Sanitary
Standard for Drinking Water (GB5749-85). For decentralized water supply, sufficient
protection of the water sources should be provided to ensure drinking water safety.
12.5 Environmental Monitoring
The project is a small water conservancy and hydropower project, and will not
produce wastewater or gases in the operation process. The water quality will not get
worse after the power generation process, so the environmental monitoring program
will mainly be for the construction period.
12.5.1 Construction production of wastewater and domestic sewage monitoring
During the peak period of the construction production, the production of
wastewater discharged from the main construction subsidiary enterprises will be
uniformly monitored through sampling 1-2 times, and the monitored items will
mainly consist of the PH value, suspended solids and petroleum. In the dam area and
living and office area of the powerhouse, we will collect domestic sewage 1-2 times
for monitoring, and there will be 7 main monitoring items, namely, the PH value,
suspended solids, COD, BOD5, ammonia nitrogen, total phosphorus and coliform.
The purpose of this monitoring program is to understand the discharge of wastewater
and its influence over the river water quality.
12.5.2 Construction noise pollution and air pollution monitoring
The project is small, and the monitoring points are located in the main
construction and production sites, living areas and on both sides of the construction
and transportation main road. The items to be monitored are: levels of noise, SO2,
NO2, and total suspended particulates. It will be better to set the monitoring time in
the early and middle stage of the construction, in order to provide the basis for labor
hygiene protection of the construction personnel.
12.5.3 Population health condition monitoring in the construction area
To timely grasp the physical health of the construction personnel and effectively
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control the spreading of infectious diseases, we should monitor the health condition of
the construction personnel throughout the construction period, focusing on monitoring
the incidence rate change of insect borne infectious diseases like malaria, epidemic
encephalitis B and water-borne infectious diseases like bacillary dysentery, typhoid
fever, paratyphoid fever, viral hepatitis, etc. to provide the basis for construction
management. This work should concurrently be under the management the
construction medical station or the township health center.
12.6 Budget Estimation of Environmental Protection Design
Environmental protection investment refers to the environmental protection
investment projects of the power station project and the environmental protection
measures taken in order to reduce any adverse effects of the project. Environmental
protection investment of the project includes three sections including environmental
protection investment in the construction area, population health protection
investment, and environmental protection, monitoring and supervision during the
construction period. The total environmental protection investment in the construction
period is 8,800 US Dollars.
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Drawings of CHIPOTA FALLS Station
1. Hydraulic-Plane Layout of CHIPOTA FALLS Station (Compared Plan) 01
2. Hydraulic-Plane Layout of CHIPOTA FALLS Station (Recommended Plan) 02
3. Hydraulic-Plane Layout of Dam (Compared Plan) 03
4. Hydraulic-Plane Layout of Dam (Recommended Plan) 04
5. Hydraulic-Design Diagram of Dam (Compared Plan) 05
6. Hydraulic-Vertical Section of Dam (Compared Plan) 06
7. Hydraulic-Design Diagram of Dam (Recommended Plan) 07
8. Hydraulic-Vertical Section of Dam (Recommended Plan) 08
9. Hydraulic-Design Diagram of Diversion System (Compared Plan) 09
10. Hydraulic-Design Diagram of Diversion System (Recommended Plan) 10
11. Hydraulic-General Plane Layout of Plant Area (Compared Plan) 11
12. Hydraulic-General Plane Layout of Plant Area (Recommended Plan) 12
13. Hydraulic-Plane Layout of Powerhouse 13
14. Hydraulic-Layout of Turbine-generator Units 14
15. Construction Organization-Layout of Construction Diversion (Compared Plan) 01
16. Construction Organization-Layout of Construction Diversion (Recommended Plan) 02
17. Construction Organization-Plane Layout of General Construction (Recommended Plan) 03
18. Construction Organization-Layout of Dam Construction Area (Recommended Plan) 04
19. Construction Organization-Layout of Penstock Construction Area (Recommended Plan) 05
20. Construction Organization-Layout of Dam Construction Area (Recommended Plan) 06
21. Construction Organization-Construction Progress Chart 07
22. Electric-Plane Layout of Electromechanical Equipments 01
23. Electric-Plane and Section of Booster Station 02
24. Electric-Main Electrical Connection Diagram 03