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NEPAL ELECTRICITY AUTHORITY (An Undertaking of Government of Nepal)
Distribution and Consumer Services Directorate
BIDDING DOCUMENT
FOR Design, Planning, Engineering, Procurement (Manufacturing/Supply),
Construction/Erection, Testing, Commissioning and Five Years of Operation &
Maintenance of 25 MWp Grid Tied Solar Farms
(EPC Contract)
Single-Stage, Bidding Procedure
IDA Cr.: Credit No. 5566-NP
Project Name: Grid Solar and Energy Efficiency Project
Issued on: …………………
Invitation for Bids No.: GSEEP/ICB-071/72-01 ICB No.: GSEEP/ICB-071/72-01
Employer: Nepal Electricity Authority
Country: Nepal
VOLUME II-PART 2 OF 2
April 2015
Acronyms
The Project Manager
Grid Solar and Energy Efficiency Project
Distribution and Consumer Services Directorate
Nepal Electricity Authority
Durbarmarg, Kathmandu, Nepal
Tel.: +977-1-4153145
Fax.: +977-1-4153146
E-mail: [email protected]
Table of Contents
1. General Description of Project Sites
2. General Survey Report of Selected Project Sites
Name of the Project: Grid Solar and Energy Efficiency Project Location: Development Region: Central Development Region Zone: Bagmati and Narayani District: Nuwakot and Makwanpur
S.No. Description of Hydropower plants
Location Co-ordinates District
Northing Easting
1 Devighat
1.1 Raatmatey Area Charghare VDC 27O 52’ 58.47” 85O 7’ 29.78” Nuwakot
1.2 Keraghari Area Charghare VDC 27O 52’ 47.67” 85O 7’ 23.67” Nuwakot
1.3 Staff Quarter Area Bidur Municipality
27O 53’ 43.32” 85O 8’ 15.65” Nuwakot
1.4 Forebay Ground Charghare VDC 27O 53’ 23.43” 85O 7’ 59.94” Nuwakot
2 Trisuli
2.1 Area 2 Bidur Municipality
27O 56’ 35.56” 85O 9’ 28.36” Nuwakot
3 Kulekhani I
3.1 Markhu Markhu VDC 27O 37’ 8.87” 85O 9’ 2.61” Makwanpur
Topographical Survey
Site Location
The following images shows the areas within the premises of Devighat Hydropower Plant,
Trisuli Hydropower Plant and Kulekhani I Hydropower Plant where the installation of the Grid
Solar Power Plant will take place.
Fig 1: Site Location of different Hydropower Plants
Fig 2: Location of Raatmatey, Keraghari, Staff Quarter area and Forebay ground in Devighat
Hydropower Plant
Fig 3: Location of Markhu in Kulekhani I Hydropower Plant
Control Survey
For the international reference a Global Positioning System was followed using the
sophisticated GPS instrument to find the easting, northing and elevation of the stations in the
field. Benchmarks were established by painting to be identified as permanent structure.
Using a Total Station an open traverse was carried establishing new stations covering
entire survey area of project area. Topcon Total Station with least count 1" for measuring
horizontal angles and standard reflecting prism of an accuracy ± 5ppm was used.
Detail Topographical Survey
Various categories of survey under this heading were conducted to obtain information
and parameters necessary for the design purposes.
While surveying we located all existing right of way property lines and easement
including type size and bearings. Existing structures such as buildings, fences retaining
wall, Roads, trees, electric poles and other details were accurately described.
Survey Data processing and Mapping Works
Following survey standards, a complete check of survey data was made. “Softwel Dtm”
software was used for plotting the points and generating the minor contours at interval of 1 m
followed by major contours at interval of 5 m with annotation.
All the existing features such as road, buildings, trees, rivers, walls, Kholsi (Water
Stream), cliff, rock, boulder, high flood level, water level, bridges etc. were identified and the
crossing axis alignment was assumed to generate the cross-sections. The detailed topographical
map of related location was plotted as per the required standards and scale and
presented in the following pages.
Shadow Analysis
Shadow Analysis is a tool for analyzing daylight conditions. Analyses are presented in the
form of colorful pictures – different colors denote different amount of exposure to sun
light. Shadow Analysis helps understand daylight conditions. PV arrays should be installed
in a shade-free location. To get the information about the shading of the sunlight on the
selected areas of the three hydropower plants, shadow analysis was performed.
A site assessment involves determining whether the location of the PV array will be
shaded, especially between the hours of 9 a.m. and 4 p.m. solar time (the study was conducted
from 7 AM to 6 PM). This is important, as the output of PV modules may be significantly
impaired by even a small amount of shading on the array.
In the present study, shadow analysis was conducted from real field data where shadow zone
was identified from 7 AM to 6 PM in one hour intervals. The resulting data was presented in
form of shadow map given below:
This volume presents details of geotechnical investigation of the three existing hydropower
plants where solar panel will be placed.
1 General Description
1.1 Site description
There are three sites in the project. Three hydropower stations: Devighat, Trishuli and Kulekhani
I. The site location map of all sites in google earth is shown in Fig. 1.
Fig. 1: Site location of different hydropower stations
Accurate locations of the site along with its surrounding information along with the location of
bore holes are shown in Figs 2 to10.
Geotechnical Survey
Fig. 2: Location of Raatmatay, Keraghari, Staff quarer area and Forebay ground, Devighat
hydropower plant site
Fig.3 Raatmatay area, Devighat
Fig. 4: Keraghari, Devighat
Fig. 5: Staff quarter area, Devighat
Fig. 6: Forebay area, Devighat
Fig. 7: Location map, Trishuli hydropower plant
Fig. 8: Area 2, Trishuli
Fig. 10: Markhu, Kulekhani with bore hole positions
2 General Geology, Geomorphology and Seismicity
2.1 General Geology and Geomorphology
Geologically, Nepal has been divided into five different zone such as Terai zone, Sub-Himalaya,
Lesser Himalaya, Higher Himalaya and Tibetan Tethys zone as shown in the geological map of
Nepal in Fig. 11.
The present sites Devighat, Trishuli lies in lesser Himalaya zone composed of Kn (Kuncha) rock
group which is composed of bedded schists, phyllites, metasandstones and quartzites. However,
at site, these rocks are completely weathered upto a depth of 4m and residual soil is only found at
sites. Similarly, Markhu, Kulekhani site also lies in lesser Himalaya zone but composed of
Bhimphedi group (Bh) rocks. Bh group mainly consists of schists and quartzites. At site,
however, only residual soil in the form of clay, clay with gravel and gravel with sand were found.
The location of sites in geological map is shown in Fig. 12.
Fig 11: Geological map of Nepal (Dahal 2006)
Fig. 12: Site location in geological map
2.2 Seismicity
Due to Tectonic Forces, Himalayan zones and the neighboring areas are seismically very active.
Most of epicenters of earthquakes are found to be located in the unstable zones. The frequency
and intensity of earthquakes are found at the weakness of the crust such as major faults, major
bends or major acres. Location of Nepal in the Himalaya along with major tectonic boundary and
various longitudinal zones of the Himalaya are shown in Fig 13.
Seismic hazard map of Nepal is also shown in Fig 14. Figure 14 shows that earthquake with a
peak acceleration of 0.3-0.5g may occur in 50 years, making the country very vulnerable to
earthquake.
Fig 13 Location of Nepal in the Himalaya along with major tectonic boundary and various
longitudinal zones of the Himalaya (Bhandary et al. 2013)
Fig 14 Seismic hazard map of Nepal (source: USGS)
3 Geotechnical Survey
3.1 Methodology
3.1.1 Field work Procedure
Field works involved percussion Drilling mechanism for drilling and sampling of the boreholes
where it was applicable to the maximum depth of 20m from the ground level and SPT were taken
at every 1m intervals and are recorded. Borehole logs were prepared at the site on the basis of the
visual observation of the soil obtained from the boreholes. The boreholes logs are attached to the
annexes are later verified by lab test results.
3.1.2 In-situ Tests
Field works involved Percussion Drilling mechanism for drilling and sampling of the boreholes
in the proposed area to the depth of 4m from the ground levels and SPT were taken at every 1m
intervals and are recorded. Borehole logs were prepared at the site on the basis of the visual
observation of the soil obtained from the boreholes. The boreholes logs are attached to the
annexes are later verified by lab test results.
Standard Penetration Test (SPT):
It consists of driving a Split Spoon Sampler with an outside dia. of 50 mm into the soil at the
base of borehole. Driving is accomplished by a drop of hammer weighing 63.5 kg falling freely
through a height of 750 mm onto the drive head. First of all the spoon is driven 150mm into the
soil at the bottom of the borehole. It is then driven further 300mm and the number of blows (N
values) required to drive this distance is recorded.
Fig 17 Standard Penetration Test Procedures
Table 3: Relation of N value to Relative Density and friction angle for granular soils
N value Relative Density Friction Angle
0-4 Very loose 26-30
4-10 Loose 28-34
10-30 Medium Dense 30-40
30-50 Dense 33-45
Over 50 Very Dense <50
Fig 18 Angle of shearing resistance for different SPT N value
Table 4: Relationship of N Value to Strength and Consistency for Cohesive Soils
N value Consistency Strength Qu
<2 Very Soft < 25
2-4 Soft 25-50
4-8 Medium Stiff 50-100
8-15 Stiff 100-200
15-30 Very Stiff 200-400
>30 Hard 400-800
3.1.3 Sampling
(i) Disturbed Sample:
Before any sample was taken, the borehole was cleaned up of loose disturbed soil deposited
during drilling operation. The samples which were obtained from bailer and in the SPT tubes
were preserved as representative disturbed samples for finding out physical properties. The
samples thus obtained were placed in airtight double plastic bags, labeled properly for
identification and later transported to the lab for analysis.
(ii) Undisturbed Sample:
Undisturbed samples were extracted using thin Shelby tube sampler. The moisture content was
maintained as natural.
3.2 Laboratory Tests
Disturbed and Undisturbed samples were collected and transported to the laboratory for the
following tests.
Sieve analysis
Natural Moisture Content
Bulk density and Dry Density
Specific Gravity
Direct shear test
Consolidation test
Unconfined compression test
4 Observation and Results
4.1 Field Investigation Results
The drilling works were carried out from the ground level to a depth of 4 m. The major soil
profiles in each bore log are shown in Table 5:
Table 5: Major soil profile in each bore logs
Site/Area BH No Depth Soil type
Devighat/Ratamatey 1
0-4m
Reddish clay
2
Devighat/Keraghari
1
2
Devighat/ Staff
quarter area
1 0-2m
2-4m
Sand with gravel
Gravel with boulders 2
3
4
Devighat/ Forebay 1 0-2m
2-4m
Gravel with sand
Gravel with sand and boulder Trishuli/ Area2 1 0-2m
2-4m
Sand with gravel and fines
Gravel with sand and boulders 2
Trishuli/ Reservior
pond
1 0-1m
1-4m
Sand with fines
Sand with gravel and boulders
2 0-2m
2-4m
Sand with gravel and fines
Gravel with sand and fines
3 0-1m
1-4m
Gravel with sand and fines
Gravel with sand and boulders 4
Kulekhani/Markhu 1 0-2m
2-4m
Clay with gravel
Gravel with boulders
2 0-3m
3-4m
Clay with sand and gravel
Blackish medium stiff clay
Measured Standard Penetration Test (SPT) values are found in the range of 5 to more than 50 in
the in-situ soil strata at different levels. Standard Penetration Tests (SPT) was conducted on each
bore holes at 1m interval, starting the first test at 1m. Laboratory test such as grain size
distribution, dry unit weight, natural moisture content, specific gravity, Shear strength properties
of soil samples were conducted on disturbed soil samples extracted with standard procedure
using Shelby (thin wall) tubes and from bailer. The bore log profile is shown in Appendix I.
4.1.1 Ground Water Table
Ground water tables (GWT) were not found during the soil investigation works. As the site has
water only during the rainy season, during soil investigation, the water table in the bore hole was
not observed.
4.2 Laboratory Investigation Results
4.2.1 Index Properties
The result of physical and index properties of soil samples collected from different depths are
presented in the attached summary sheet.
The grain size distribution curves of soil sample are classified as USCS Soil Classification
System in which most of the soil fall in ML groups. Specific Gravity determination on selected
soil samples is in the range of 2.32 to 2.70.
Natural moisture content of soil is approximately 9-36%. Liquid limit of soil is in the range of
31-47. Soil samples are low to medium plastic silts and clay.
4.2.2 Strength Parameters
Unconfined compression tests were conducted on undisturbed samples. Unconfined compressive
strength for the tested samples was in the range of 75 to 275 KN/m2. Corresponding undrained
shear strengths are in the range of 37.5-137.5 KN/m2 for the tested samples. Cohesion and
friction angle of the tested cohesionless samples were in the range of 0-30.2 KN/m2 and 5.6-
38.2°, respectively.
5 Bearing Capacity Analysis
5.1 General
Bearing capacity of footing is the ultimate load that the soil can take without shear failure or
excessive settlement. Thus the foundation should be designed against both shear failure and
excessive settlement. In this report, the allowable settlement of soil is taken as 25mm. If the
allowable settlement increases, the bearing capacity will increase accordingly. For the foundation
of solar panel, isolated or strip footing may be used.
5.2 Depth of Foundation
The depth of foundation is governed mainly by factors like scour depth, depth to ground freeze
and the nature of the subsoil strata to place the foundation. The types of foundation analyzed
comprise an open foundation. The depths used in the analysis are 2m from ground position.
5.3 Computation of Bearing Capacity in soils
The bearing capacity analysis has been carried out for foundation soil at 2.0 m depth from
ground. In the analysis, both shear failure and settlement criteria are taken into account. The
bearing capacity analysis was carried out based on the results of SPT N-value. The open
foundation is a large footing extending over a great area.
5.3.1 Cohesionless soil
The well-known Teng’s equation has been used to compute bearing capacity of soil on the basis
of shear failure criteria. The width of foundation used in the analysis is varied. For solar panel,
either isolated footing or strip footing can be used.
The following equation is used to determine bearing capacity from shear failure criteria.
qfns WDNBWNq )100(67.022.0 22 (1)
The bearing capacity of open foundation for cohesionless soils can also be obtained using
settlement criteria as explained by different researchers below:
i. Teng (1969) based on the curves developed by Terzaghi and Peck (1948)
2
2 0.3( / ) 35( 3)
2p d w
Bq KN m N F R
B
(2)
where qp is the net allowable bearing pressure for allowed settlement of 25 mm, N is the
corrected SPT, B is the width of the footing, Rw is the water table correction factor (Rw= 1+z2/B),
where z2 is the depth of water table from footing level, Fd is the depth factor (Fd = 1+0.2*D/B ≤
1.2)
ii. Meyerhof (1956)
For B > 1.2m, for open foundations
2
2 0.3( / ) 8p d w
Bq KN m N F R
B
(3)
Fd is given by Fd = 1 + 0.33 D/B ≤ 1.33.
Experimental results have shown that Teng’s and Meyerhof’s equations for bearing capacity
(BC) are too conservative. Bowles (1988) has increased BC by 50 % and given by:
iii. Teng’s Equation (modified)
2
2 0.3( / ) 53( 3)
2p d w
Bq KN m N F R
B
(4)
Eq. (3) is also proposed by Teng for 40 mm settlement.
iv. Meyerhof’s Equation (modified)
2
2 0.3( / ) 12.5p d w
Bq KN m N F R
B
(5)
For the settlement of 40 mm, net allowable bearing pressure is given by:
''
25p p
Sq q (6)
v. Bearing Capacity from IS Code (2950 – 1956):
I.S. 2950 – 1956 gives the code of practice for design and construction of raft foundation:
For 25mm settlement,
qsafe (KN/m2) = 17.5 (N – 3)RW (7)
vi. Bearing Capacity from IS Code (6403 – 1971):
I.S. 6403 – 1971 accepted Teng’s equation for 40 mm settlement, without depth factor, given by
2
2
2
0.3( / ) 55( 3)
2p w
Bq KN m N R
B
(8)
vii. Peck’s method
Peck’s method is also considered for analysis for evaluation of safe bearing pressure of footing.
The safe bearing pressure is evalauted as:
NSCq wnp 41.0 (9)
where
Cw= water table correction factor given by
Cw = 0.5 + 0.5 × Dw / (Df + B)
Using the relationships suggested above the analysis was carried out. The results of analysis are
summarized in Table No. 2.
5.3.2 Cohesive soil
To calculate the bearing capacity of cohesive soil, Both the Terzaghi’s method and Skempton’s
method will be used. The bearing capacity equations are:
Terzaghi’s net ultimate bearing capacity equation is:
L
BCq
nu3.017.5 (10)
Similarly, Skempton’s net ultimate bearing capacity is given by:
cnuCNq (11)
5.2B
Dfor 2.012.015 f
)(
L
B
B
DN
f
recC (12)
The safe bearing capacity is obtained by dividing net ultimate bearing capacity by factor of
safety, FS (=3).
The calculated bearing capacity with major soil type is shown in Table 6.
Table 6 – Computation of Bearing Capacity of Foundation
Site/Area BH No Major soil type SPT value
(N)
Depth
(D)
Width (B) Net Allowable
Bearing Capacity
(qna, KN/m2)
Devighat/Ratamatey 1 Cohesive (silt,
clay)
6 2m 1m 68
2 Cohesive (silt,
clay)
7 2m 1m 80
Devighat/Keraghari
1 Cohesive (silt,
clay)
7 2m 1m 80
2 Cohesive (silt,
clay)
7 2m 1m 80
Devighat/ Staff quarter
area
1 Cohesionless
(sand, gravel)
40 2m 1m 323
2 Cohesionless
(sand, gravel)
33 2m 1m 262
3 Cohesionless
(sand, gravel)
30 2m 1m 236
4 Cohesionless
(sand, gravel)
26 2m 1m 198
Devighat/ Forebay 1 Cohesionless
(sand, gravel)
50 2m 1m 411
Trishuli/ Area2 1 Cohesionless
(sand, gravel)
50 2m 1m 411
2 Cohesionless
(sand, gravel)
50 2m 1m 411
Kulekhani/Markhu 1 Cohesive (silt,
clay)
5 2m 1m 57
2 Cohesive (silt,
clay)
5 2m 1m 57
Fig 19: Open foundation bearing capacity sample calculation (Trishuli/ reservoir pond/ BH-2)
KN/m2
6 Recommendation
Geotechnical profile along different bore hole shows both cohesive soils and cohesionless soils at
different depths. The depth of foundation can be kept as 2m and either the isolated footing
(rectangular/ square, size 1-2m) or the strip footing (width = 1-2m) can be adopted. The
recommended bearing capacity for different sites along with dominant soil profile is as follows:
Site/ Area Soil type Recommended
bearing capacity (KN/m2)
7 References:
USGS (United State Geological Survey):
http://earthquake.usgs.gov/earthquakes/world/nepal/gshap.php
Bhandary, NP; Yatabe R; Dahal RK; Hasegawa S and Inagaki H (2013): Areal distribution of
large scale landslides along highway corridors in central Nepal. Georisk: Assessment and
Management of Risk for Engineered Systems and Geohazards,
DOI:10.1080/17499518.2012.743377
Dahal, R., K., 2006, Geology for Technical Students, Bhrikuti Academic Publications,
Kathmandu, Nepal, 756p.
Devighat/ Raatmatay Cohesive (silt, clay) 68
Devighat/ Keraghari Cohesive (silt, clay) 80
Devighat/ Staff quarter area Cohesionless (sand, gravel) 198
Devighat/ Forebay ground Cohesionless (sand, gravel) 411
Trishuli/ Area 2 Cohesionless (sand, gravel) 411
Kulekhani/ Markhu Cohesive (silt, clay) 57
USCS
Coarse to
mediumFine
% % % % % % % % gm/cc gm/cc KN/m2 c (kPa) φ°
1 0-1m CL 89 47 33 14 32.1 1.82 1.38 2.32 75.4
2 0-1m CL 76 45 33 12 29.6 1.78 1.37 2.45 95.7
1 0-1m CL 80 42 33 9 25.4 1.69 1.35 2.55 92.4
2 0-1m CL 83 42 35 7 27.8 1.72 1.35 2.49 85.9
1 0-1m CL 75 35 24 11 32.4 1.58 1.19 2.56 15 32.4
2 1-3m SP 34 1 17.8 1.92 1.63 2.67 0 33.2
3 1-2m SP 36 1 15.4 1.87 1.62 2.62 0 31.8
4 1-2m SP 38 1 16.2 1.72 1.48 2.66 0 30.9
Devighat/ Forebay 1 0-2m GP 83 1 12.8 1.69 1.50 2.67 0 35.2
1 0-1m SP 29 5 13.4 1.81 1.60 2.64 2 36
2 1-2m SP 29 4 15.6 1.76 1.52 2.68 1.2 35.9
1 2-3m CL 86 43 26 17 34.2 1.68 1.25 2.59 150.8
2 2-3m CL 82 43 25 18 29.8 1.59 1.22 2.52 172.4
3 2-3m CL 88 43 27 16 35.9 1.72 1.27 2.55 275.4
4 2-3m CL 87 44 26 18 34.6 1.82 1.35 2.61 200.4
1 0-1m SM 23 31 NA 15.2 1.86 1.61 2.64 15.4 9.8
2 2-3m SM 34 33 NA 16.4 1.88 1.62 2.62 30.2 5.6
Specific
Gravity
Unconfined
compression
strength (2m
depth UD)
Liquid
Limit
Plastic
Limit
Plasticity
Index
Classi-
fication
System
Gravel
Dry
Density
Sand Silt &
Clay
77
61
66
66
68
14
18
Direct shear test (at
2m depth UD sample)
11
24
20
Trishuli/ Area2
Trishuli/ Area5
Percentage of Atterberg LimitsNatural
Moisture
content
Moist
Density
Kulekhani/Markhu
63
Devighat/Keraghari
Devighat/ Staff
quarter area25
65
12
Depth (m)BH NoSite/Area
Devighat/Ratamate
17
16
13
Project: Soil Investigation Works for Nuwakot Beltar Site
Location : Nuwakot, Makwanpur
