NEPAL ELECTRICITY AUTHORITY

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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

1 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.: Project Name: Issued on: Invitation for Bids No.: ICB No.: Employer: Country: Credit No NP Grid Solar and Energy Efficiency Project GSEEP/ICB-071/72-01 GSEEP/ICB-071/72-01 Nepal Electricity Authority Nepal VOLUME II-PART 2 OF 2 April 2015 The Project Manager Grid Solar and Energy Efficiency Project Distribution and Consumer Services Directorate Nepal Electricity Authority Durbarmarg, Kathmandu, Nepal Tel.: Fax.: mmddcsd@gmail.com Acronyms

2 Table of Contents 1. General Description of Project Sites 2. General Survey Report of Selected Project Sites

3 Topographical Survey 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 Location Co-ordinates District Hydropower plants Northing Easting 1 Devighat 1.1 Raatmatey Area Charghare VDC 27 O O Nuwakot 1.2 Keraghari Area Charghare VDC 27 O O Nuwakot 1.3 Staff Quarter Area Bidur 27 O O Nuwakot Municipality 1.4 Forebay Ground Charghare VDC 27 O O Nuwakot 2 Trisuli 2.1 Area 2 Bidur Municipality 27 O O Nuwakot 3 Kulekhani I 3.1 Markhu Markhu VDC 27 O O Makwanpur

4 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

5 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

6 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.

7 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.

14 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:

Geotechnical Survey This volume presents details of geotechnical investigation of the three existing hydropower plants where solar panel will be placed. 1 General Description 1.

27 Geotechnical Survey 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.

28 Fig. 2: Location of Raatmatay, Keraghari, Staff quarer area and Forebay ground, Devighat hydropower plant site Fig.3 Raatmatay area, Devighat

29 Fig. 4: Keraghari, Devighat Fig. 5: Staff quarter area, Devighat

30 Fig. 6: Forebay area, Devighat Fig. 7: Location map, Trishuli hydropower plant

31 Fig. 8: Area 2, Trishuli

32 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.

Most of epicenters of earthquakes are found to be located in the unstable zones.

33 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.

5g may occur in 50 years, making the country very vulnerable to earthquake.

34 Seismic hazard map of Nepal is also shown in Fig 14. Figure 14 shows that earthquake with a peak acceleration of g 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 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

35 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 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

36 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 Loose Medium Dense Dense 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 < Soft Medium Stiff Stiff Very Stiff >30 Hard

37 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:

38 Table 5: Major soil profile in each bore logs Site/Area BH No Depth Soil type Devighat/Ratamatey m Devighat/Keraghari 1 Reddish clay 2 Devighat/ Staff 1 quarter area 0-2m 2-4m Devighat/ Forebay 1 0-2m 2-4m Trishuli/ Area m 2 2-4m Sand with gravel Gravel with boulders Gravel with sand Gravel with sand and boulder Sand with gravel and fines Gravel with sand and boulders Trishuli/ Reservior pond 1 0-1m 1-4m 2 0-2m 2-4m 3 0-1m 4 1-4m Kulekhani/Markhu 1 0-2m 2-4m 2 0-3m 3-4m Sand with fines Sand with gravel and boulders Sand with gravel and fines Gravel with sand and fines Gravel with sand and fines Gravel with sand and boulders Clay with gravel Gravel with boulders 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 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.

39 4.2 Laboratory Investigation Results 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 Natural moisture content of soil is approximately 9-36%. Liquid limit of soil is in the range of Soil samples are low to medium plastic silts and clay 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/m 2. Corresponding undrained shear strengths are in the range of KN/m 2 for the tested samples. Cohesion and friction angle of the tested cohesionless samples were in the range of KN/m 2 and , 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.

40 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 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. 2 2 q 0.22N BW 0.67(100 N ) D W ns (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) f q 2 B 0.3 q ( KN / m ) 35( N 3) F R 2B p d w 2 (2) where q p is the net allowable bearing pressure for allowed settlement of 25 mm, N is the corrected SPT, B is the width of the footing, R w is the water table correction factor (R w = 1+z 2 /B), where z 2 is the depth of water table from footing level, F d is the depth factor (F d = 1+0.2*D/B 1.2) ii. Meyerhof (1956) For B > 1.2m, for open foundations 2 B 0.3 q ( KN / m ) 8N F R B p d w 2 (3) F d is given by F d = D/B 1.33.

41 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 B 0.3 q ( KN / m ) 53( N 3) F R 2B p d w 2 (4) Eq. (3) is also proposed by Teng for 40 mm settlement. iv. Meyerhof s Equation (modified) 2 B 0.3 q ( KN / m ) 12.5N F R B p d w 2 (5) For the settlement of 40 mm, net allowable bearing pressure is given by: q p S ' ' qp (6) 25 v. Bearing Capacity from IS Code ( ): I.S gives the code of practice for design and construction of raft foundation: For 25mm settlement, q safe (KN/m 2 ) = 17.5 (N 3)R W (7) vi. Bearing Capacity from IS Code ( ): I.S accepted Teng s equation for 40 mm settlement, without depth factor, given by 2 B 0.3 qp( KN / m ) 55( N 3) R 2B 2 w2 (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: q 0. C NS (9) np 41 where C w = water table correction factor given by C w = D w / (D f + B) w

42 Using the relationships suggested above the analysis was carried out. The results of analysis are summarized in Table No 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: B q nu.7c L 5 (10) Similarly, Skempton s net ultimate bearing capacity is given by: q CN nu c (11) D Df for 2.5 ( ) f B N (12) C rec B L B 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) Devighat/Ratamatey 1 Cohesive (silt, clay) 2 Cohesive (silt, clay) Devighat/Keraghari 1 Cohesive (silt, clay) 2 Cohesive (silt, clay) Devighat/ Staff quarter 1 Cohesionless area (sand, gravel) 2 Cohesionless (sand, gravel) 3 Cohesionless (sand, gravel) 4 Cohesionless (sand, gravel) Devighat/ Forebay 1 Cohesionless (sand, gravel) Trishuli/ Area2 1 Cohesionless (sand, gravel) Depth (D) Width (B) 6 2m 1m m 1m m 1m m 1m m 1m m 1m m 1m m 1m m 1m m 1m 411 Net Allowable Bearing Capacity (q na, KN/m 2 )

43 2 Cohesionless (sand, gravel) 50 2m 1m 411 Kulekhani/Markhu 1 Cohesive (silt, clay) 2 Cohesive (silt, clay) 5 2m 1m m 1m 57 KN/m 2 Fig 19: Open foundation bearing capacity sample calculation (Trishuli/ reservoir pond/ BH-2)

44 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/m 2 ) 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 7 References: USGS (United State Geological Survey): 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: / Dahal, R., K., 2006, Geology for Technical Students, Bhrikuti Academic Publications, Kathmandu, Nepal, 756p.

45 Project: Soil Investigation Works for Nuwakot Beltar Site Location : Nuwakot, Makwanpur Site/Area Devighat/Ratamate USCS Percentage of Atterberg Limits Unconfined Natural Sand Moist Dry compression Direct shear test (at Classification Fine Clay Limit Limit Index content Gravity Silt & Liquid Plastic Plasticity Moisture Specific BH No Depth (m) Gravel Coarse to Density Density strength (2m 2m depth UD sample) medium depth UD) System % % % % % % % % gm/cc gm/cc KN/m 2 c (kpa) φ 1 0-1m CL m CL Devighat/Keraghar 1 0-1m CL Devighat/ Staff quarter area 2 0-1m CL m CL m SP m SP m SP Devighat/ Forebay 1 0-2m GP Trishuli/ Area m SP Trishuli/ Area m SP m CL m CL m CL Kulekhani/Markhu 4 2-3m CL m SM NA m SM NA

Boreholes. Implementation. Boring. Boreholes may be excavated by one of these methods: 1. Auger Boring 2. Wash Boring 3.

Boreholes. Implementation. Boring. Boreholes may be excavated by one of these methods: 1. Auger Boring 2. Wash Boring 3. Implementation Boreholes 1. Auger Boring 2. Wash Boring 3. Rotary Drilling Boring Boreholes may be excavated by one of these methods: 4. Percussion Drilling The right choice of method depends on: Ground