China - PCF Xiaogushan Hydropower Project : environmental assessment (Vol. 2 of 3) : Supplementary EIA report

E966 Vol. 2 THE PEOPLE'S REPUBLIC OF CHINA ZHANGYE XIAOGUSHAN HYDROPOWER PROJECT IN GANSU PROVINCE Supplementary EIA Report East China Investigation and Design Institute Zhangye Xiaogushan Hydropower Co. Ltd. May 2004, Hangzhou FIl!E COP>'  List of Contents 1. Preface .....................................................1 2. EIA of Cascade Hydropower Developments in Heihe River Basin .2 2.1 General of Heihe River basin .................................................. 2 2.2 Cascade Hydropower Developments in River Basin .....................3 2.3 Environment Assessment on Cascade HPPs on Heihe River .......7 3. Environment Assessment of 35kV and 110kV Transmission Lines 13 3.1 General .................................................... 13 3.2 Regional Environment Along Line Route . .................................... 13 3.3 Environment Assessment of Construction . .................................. 16 4. Alternatives Comparison and Analysis . ......................................... 18 4.1 Comparison of Dam ....................... ............................. 18 4.1.1 Engineering Features of Dam Selected . ................................... 18 4.2 Analysis on the case without Xiaogushan HPP ........................ 23 4.3 Recommendation for Dam .................................................... 23 5. Analysis of Rock Specimen .................................................... 24 6. Analysis of Selection of Spoil Areas ................................................ 25 7. Impact Scope ofXia-ogushan Project .. 26 7.1. Impact Scope of Xiaogushan Project .................................. 26 7.2 Reservoir Inundation ............. .. .................. 27 7.3 Road and Traffic .. ................................ 27 8. Analysis of Environmental Influence at Construction Camp ..28 8.1 Design of Construction Camp .28 8.2 Analysis of "Three Wastes" Emission at Camps ..29 8.3 Measure of controlling pollution . .30 8.4 Investment on environmental protection . .31 9. Plan of Xiaogushan dam safe .32 9.1 Plan of construction supervision and quality guarantee .. 32 9.2 Plan of instrumentation ..38 9.3 Plan of operation and maintenance . .38 9.4 Plan for emergence conditions . .39 10. Survey on fishes resources . .45 10.1 Survey on fishes resources .45 10.2 Survey on Terraneous Biology .46 11.Survey of Cultural Relic and Historic Sites . . . 47 1 1.1 Survey organization and surveyors .47  11.2 Surveys ............................................ 47 11.3 Survey result ............................................ 47 11.4 Measures for occasionally discovery of cultural relics ......... ..... 47  i I I i i i I I  1. Preface Based on "Management Categories of Environmental Impact for Construction Projects" and "Rules for Approval of Environment Assessment for Construction Projects" (Order No.15 issued by State Environmental Protection Administration, Nov. 1, 2002), this project is categorized as of water conservancy project, and the environment assessment report of the project should be compiled for approval by Gansu Environment Protection Bureau. Because this project is related to Qilian Mt. National Natural Conservation Area and according to "Rules for Approval of Environment Assessment for Construction Projects", the opinions of the State Environmental Protection Administration had been solicited before approval by local environment management department. Attachments 1 - 5 of the main report contain the related documents and official replies from the State Environmental Protection Administration and Gansu Environment Protection Bureau. Entrusted by Xiaogushan Hydropower Project Co. Ltd. (herein after referred to as XHC), East China Investigation and Design Institute (herein after referred as ECIDI) completed the EIA Report of Xiaogushan Hydropower Project (for World Bank) in January 2004. In April 2004, the Supplementary Report to the above mentioned EIA Report was prepared, which added the following aspects: environmental impact caused by cascade development in Heihe River Basin, environmental impact caused by 35kV and 11 OkV transmission line for power supply, comparative selection of construction schemes, lithological analysis, selection of spoil areas, project impact scope, analysis on environmental impact at construction camps, impact analysis biological environment, dam safety plan, and survey on fishes and cultural relics. -,  2. EIA of Cascade Hydropower Developments in Heihe River Basin 2.1 General of Heihe River basin 2.1.1 Hydrology Heihe River is the second large inland river at the northwest of China, originated from Qiliangshan mountain area at the north of Qinghai-Tibet highland, flowing through Qinghai, Gansu and Inner Mongolia province (district), the total length of main stream 821km, with valley area 11.6 x 104 km2. It is limited at Yinluoxia and Zhengyixia gorge dividing as the upper, middle and lower reaches. The upper reaches divides into the east branch and the west branch, the east branch originated at Jinyaoling 100km long; the west branch originated at Yayaozhang 175km long. Two branches are combined at Huangzhangsi at the northwest of Qilian county of Qinghai province, flowing at the north 90km to Yinluoxia gorge. The catchment area of the upper reaches is 1.0 x 104 kM2, with river course 303 km long, riverbed gradient 1%o, natural head about 3000m. The middle reaches is from Yinluoxia to Zhengyixia gorge, catchment area 2.56 x 104 km2, with river course 185 km long; The lower reaches is after Zhengyixia gorge, catchment area 8.04 x 104 kM2, with river course 333km long. The runoff of Heihe River is mainly from precipitation of Qilianshan mountain area and melting water from snow, the long-term mean annual flow at Yinluoxia gauge station is 15.80 x 1 08m3, at Liyuanbao gauge station 2.37 x 108M3, and along other tributary 6.58 x 108m3, total long-term mean annual flow from the mountain mouth 24.75 x 108M3. The underground water is added mainly by river flow, the un-repeated quantity of underground water resource and surface runoff is about 3.33 x 108m3. The total of water resource is 28.08 x 108m3. 2.1.2 Ecological environmental condition The natural ecological environment of Heihe River is relatively complex, with more precipitation in the upper reaches but short of heat resource. The forest and meadow ecological system is mainly spreading on back slope at El.2600 - 3400m. The sunshine and land resource in middle and lower reaches is rich, but short of water resource. The most is of barren land ecological environment excluding agriculture ecological system and artificial forest. According to the topography, landform and depth of human development, it can be divided into the south mountainous sub-ecology system, the middle reaches oasis ecological system, and north oasis peripheral desert ecological system of middle and lower reaches. The area of mountainous sub-ecology system is about 43372.5 km2, oasis ecological system 11488.55 km2, desert ecological system 74210.85 km2, accounting for 33.6%, 8.9% and 57.49% of whole valley area respectively. Evidently, the -2 -  proportion of desert ecological system is biggest, the second mountainous sub-ecology system and the smallest the oasis sub-ecological system. 2.1.3 Social and economic condition The major estate in Heihe River basin is of agriculture, and it is centralized in the middle reaches. After 80's, the development of industry and the 3rd industry is rapid. For Gansu province in the middle reaches, the domestic total output value in 2000 is 1080352 x 104 Yuan, in which the agricultural output is 369523 x 104 Yuan, accounting for 34.20%; Industrial output value 385673 is x 104 Yuan, accounting for 35.70%; The 3rd industrial output value is 325156 x 104 Yuan, accounting for 30.10%. 2.2 Cascade Hydropower Developments in River Basin For the purpose of hydropower development, the original Northwest China Investigation and Design Institute prepared "Heihe basin stepped development study" in 1957 D 1960. By this report, there are 11 dam sites from Huangzhangsi to Yinluoxia gorge(Fig.1, Fig.2) including Huangzhangsi, Sandaoheigou, Chouniugou, Sandaowan, Songmugou, Dagushan, Siyangling (Xiaogushan), Longsou, Xiliushui, Yinluoxia, Longxi-l and Longxi-ll, in which Huangzhangsi and Dagushan have regulation capacity and others are riverbed type or diversion type power station. Now, the preparation of existing Longsou project, Xiliushui and Xiaogushan project is based on this report. For the purpose of reasonable development of water resource and solving water-use contradiction, the original Ministry of Water Resources and Hydropower entrusted Lanzhou Investigation and Design Institute to carry out water conservancy planning of Heihe River in 1982. In 1988, Lanzhou Investigation and Design Institute completed 'Water conservancy planning of main stream of Heihe River (including LiYuanhe river)" under the support and coordination of relative provinces (region). This report made a full study of planning result by relative design units. Dagushan was cancelled due to its poor condition of reservoir, short of construction material, poor condition for traffic and construction. The additional survey and alternative comparison was made for Ladongxia, youhulu, Erzhulong, Huangzhangsi. Erlongzhu reservoir in the upper reaches, Caolixi project in the middle reaches, Zhengyixia reservoir, Dadunmen diversion project and Ganmeng water conveyance system project in the lower reaches were recommended. The "Allocation scheme of water quantity in main trunk of Heihe River" was approved by the State Council, which was transferred through SZZE 1997E No.496 document of Ministry of Water Resources to Gansu Province and Inner Mongolia for implementation. In order to implement united management and control of water and create condition for water saving in the middle reaches, the Ministry of Water Resources entrusted Yellow river water resources committee to prepare "Short-term treatment planning of Heihe River" in 2001, which was -3-  approved formally by the State Council in Aug. 2001. This report recommended building Zhengyixia reservoir and Inner Mongolia diversion channel project in the late period of "10th -Five-Year Plan" and construct Huangzhangsi reservoir before 2010. The field survey of each dam-site between Huangzhangsi and Dagushan is not yet carried out, the main engineering parameters are not clear. Therefore, the environment assessment for upstream projects is based on information of Dagushan upstream and Xiliushui project downstream and also considering the construction of Huangzhangsi reservoir. See Attachment 6 for the details of "plan of stepped development upstream Heihe River". The main engineering parameters of Huangzhangsi, Dagushan, Xiaogushan and Xiliushui project are listed in Table 2-1. -4 -  Table 2-1 Main engineering parameters of Huangzhangsi, Dagushan, Xiaogushan and Xiliushui project No. Description Huangzhangsi Dagushan Xiaogushan Xiliushui I. Hydrology 1 Catchment area 7648km2 8230km2 9427.8km2 9884.1 km2 2 Long-term mean discharge 39.3m3/s 47.6m3/s 47.7m3/s 49.3m3/s 3 Recorded max. discharge 603m3/s 131 Om3/s 1150m3/s 4 Historic max. discharge 2300m3/s 2300m3/s 5 Recorded max. flood (day) 1.82* 108m3 0.73x 1 08m3 0.73x 108m3 6 Long-term mean suspended load 192.2x 104tVa 221 x 104t/a 221x 104t/a 7 Long-term mean sand content 1.4kg/m3 1.4kg/m3 1.4kg/m3 8 Recorded mean sand content 140kg/m3 140kg/m3 140kg/m3 9 Long-term mean bed-load 25x 104t/a 25x 104t/a II. Reservoir 1 Checked flood level 2633.1m 2200.9m 2055.4m 1922.93m 2 Designed flood level 2630.2m 2198.2m 2049m 1920m 3 Normal storage water level 2629.2m 2196.6m 2060m 1920m 4 Limited water level in flood period 2692.2m 2196.6m 1918.Om 5 Dead water level 2580.0m 2122.Om 2049m 1870m 6 Backwater length 12km 20km 3.055km 8km -5-  7 Total storage capacity 4.41 x 103m3 4.49x 108m3 140x 104m3 8620x 104m3 8 Storage capacity under normal 3.96x 108m3 4.15x 108m3 140x 104m3 8620x 104m3 storage water level. 9 Regulated storage capacity 3.4x 1 03m3 3.51 x 108m3 130x 104m3 2000x 104m3 10 Dead storage capacity 0.56x 1 08m3 0.64x 1 03m3 4800x 104m3 Ill. Power plant index 1 Installed capacity 33MW 62MW 98MW 135MW 2 Long-term mean power output 3.804x 103kW- h 5.0702x 108kW h 3 Annual utilization hours 3882h 3756h IV. Inundation loss and permanent land occupation 1 Flooded farmland 1 000mu 2 Inhabitant relocation 268 3 Flooded housing 526 rooms 4 Permanent land occupation V. Main structures 1 Dam height 202.4m 120.5m 26.5m 144.5m 2 Dam type Rock-ffacing Concrete arch dam Barrage 3 Flood releasing structure spillway e flood Overflowing Spillway releasing tunnel 4 Type of powerhouse Diversion type Diversion type Diversion type Diversion type -6-  2.3 Environment Assessment on Cascade HPPs on Heihe River 2.3.1 Analysis on mutual dependence of Xiaogushan dam and other dams The Xiaogushan dam is the third hydropower project planned in the upstream reach of the Heihe River, with the Xiliushui HPP on ist upstream side and the Dagushan HPP on its downstream side. Analysis on the water stage connection, the tail water of the Xiaogushan HPP is connecting the reservoir of Xiliushui HPP, and there is no dependence relationship to each other. The two HPP's can operate independently and will not influence each other in operation. The Dagushan HPP has a high dam (133m high) and has its normal reservoir water level at 2167m. Therefore, the tail water level of Dagushan HPP is predicted to be at El. 2043m. The normal reservoir water level of the Xiaogushan HPP is at El. 2042m. The tail water of the Dagushan may directly flow into the reservoir of the Xaogushan. Construction and operation of the Dagushan HPP will not affect the normal operation of the Xaogushan HPP and the construction of Xaogushan will neither influence the development of Dagushan HPP. The operation of the two HPP's will not be affected by each other. Analysis from the viewpoint of engineering safety, as the Xiaogushan HPP and other HPP's have their own dam safety plan, the operation of each HPP will not induce safety problem in normal operation conditions, except in the case of occurrence of big accident. 2.3.2 Analysis on influence of hydrology situation The 11 cascade developments on the upstream reach of Heihe River are all located in the experimental district of the state-level Qilian Mt. Natural Conservation Area, outside of the buffer district and central district. The Xiaogushan EIA Group of Gansu Provincial Environmental Science and Design Institute made site survey for 5 times from 2001 to 2004 and investigated into the relevant literatures. They concluded that the environmental impact caused by the hydropower projects to be built on the upstream reach of Heihe River be mainly to the hydrological conditions, i.e., (1) reducing water flow at part of the river sections and forming water-reduced river section, (2) lowering the flood water level due to storing and retarding floods and cutting flood peak. 2.3.2.1 Analysis for influence of hydrology situation (1) Cuffing flood peak By the flood computation, the peak flood at Yinluoxia gauge station after construction of Huangzhangsi reservoir will be reduced to 659 m3/so 1311 m3/so accounting for 230 O 47O o reducing water level 1 o 3.9m. The flood peak is more large and the flood peak cutting effect is more notable. The flood peak cutting and flood mitigation effect of middle and small reservoirs 7 -  in section between Yinluoxia and Dagushan is also notable. The peak flood after construction of Dagushan reservoir will be reduced to 700 m3/sEi 1110 m3/sL accounting for 240 Ei 380 . Xiaogushan, Xiliushui and Yinluoxia reservoir are of daily-regulated reservoir and the flood peak cutting effect is not obvious. In a word, the development of terraced power station at upper reaches of Heihe River can reduce efficiently flood peak. By preliminary estimation, the flood peak at Yinluoxia gauge station will be reduced to 1359 m3/sE1 2421 m3/sE accounting for 47FE 850 . Therefore, the development of terraced hydroelectric station has notable regulation role to distribute annual river runoff and increase flow in dry year and dry period, and raise utilization rate of river runoff to facilitate the enforcement of water distribution scheme. (2) Sedimentation The development of terraced power station of upper reaches of Heihe River can silt sand and increase sand content in water step by step. Refers to Fig.2-3 for sand content of each power station. By the survey, the suspended load and bed-load upstream of Heihe River is 20%. By 50 years operation of Yinluoxia and Dagushan reservoir, the suspended load is 20% and bed-load is fully silted, see Table 2-2 for the sedimentation of each station. By the field survey, the long-term suspended load at Qilianshan gauge station is 40.7 x 104 t/a, annual mean sand content 0.93 kg/m3; at Zamashike gauge station 104.8 x 104 t/a, annual mean sand content 1.48 kg/m3; at Yinluoxia gauge station 262.4x 104t/ao annual mean sand content 1.68kg/m3; at section between Qilian and Zamashike to Yinluoxia 116.9x 104t/a. By the analysis, after the operation of Huangzhangsi, Dagushan, Xiaogushan and Xiliushui power station, the annual sand transit at Yinluoxia gauge station will be reduced for 260.04 x 104Vta, and the sand remaining is only 2.36 x 104t/a. Sedimentation of Huangzhangsi, Dagushan, Xiaogushan and Xiliushui project Table 2-2 Description Huangzhangsi Dagushan Xiaogushan Xiliushui Long-term 39.3m3/s 47.6m3ls 47.7m3ls 49.3m3ls mean discharge Long-term mean sand 1.2kg/m3 1.4m3/s 1.4m3/s content Long-term mean 150.24x 104tVa 192.2x 104t/a 221x 104t/a 228.06x 104Vta suspended load - 8-  Long-term 52.86x 104tVa 38.44x 104t/a 25x 104tVa 25x 104tVa mean bed-load. Annual inflowing sand 203.1x 104tVa 230.6x 104tVa 246x 104t/a 253.06x 104t/a content Long-term mean 168x 104tVa 192x 104t/a 201.8x 104 Va 207.45x 1 04ta sedimentation Long-term mean sand 35.1 x 1 04ta 38.6x 1 04ta 44.2x 1 04ta 45.61 x 1 04ta discharge -9-  Inflow sand 203.1 x 104tt/aO suspended load 150.24x 104Vta[lbed load 52.86x 104t/aIZ Huangzhangshi Sediment 168x 104t/a Inflow sand 27.5x 104t/a[L suspended load 22 x Discharge 35.lx 104t/a[l suspended 104t/a O bed load 5.5 x loado 104t/a[l Sediment 51.18x 104t/a Dagushan . Inflow sand 15.4x 104t/a D1 4 bed load 3.08 x 104t/a 12 Discharge 11.42x 10 t/i suspended suspended load 12.32 x 104t/a[l Sediment 22.07x 104t/a Xiaogushan 4 Inflow sand 7.06x 104t/aiO 104 bed load for all _Discharge 4.75x t/a suspended Sediment 9.45x 104t/a Xiliushui < Inflow sand 9 x 104t/a L Discharge 4.75x 104t/aE suspended suspended load 7.2 x 104t/a[L bed load 1.8x 104t/a Sediment 9.45x 104t/a Yinluoxia 4 Sand discharge to Yinluoxia gauging station Fig. 2-3 Sedimentation Diagram of Cascade HPPs on Heihe River - 10-  2.3.2.2 Analysis on utilization of water resource of Heihe River Basin The development of terraced power station of upper reaches of Heihe River will efficiently regulate ecological and agricultural water supply of whole basin, ensure water discharge at Zhengyixia project, increases water supply for downstream natural vegetation, promote updating and recovery of oasis downstream, of lower reaches, at the same time helpful to raise guarantee level for water supply in irrigation area at the middle reaches and alleviate shortage of water supply during peak period in irrigation area at the middle reaches. LI 1 0 Benefit of ecologic water supply Huangzhangsi and Dagushan reservoir are head project in the water conveyance system of Heihe River and the centralized way is used for water supply to the downstream area to ensure the implementation of water distribution scheme of the State Council. The centralized way for water supply will greatly increase water conveyance efficiency of river channel at middle and lower reaches, increase ecologic water supply of Erjina county and play important role for ecologic water supply. L 20 Benefit of agriculture water supply The middle reaches of Heihe River is of drought area, annual precipitation only 110mm, but annual evaporation 1923mm, where belongs to irrigation agricultural oasis district and the crop growth is depended mainly by irrigation water. The shortage of water supply in crucial growth of plant will seriously cause reduction of agriculture products. By the benefit calculation method recommended by "Economic appraisement specification of water conservancy project" and considering local real condition, the water-shortage loss way is used for computation of benefit of middle reaches (with wheat for representative). By the survey in the middle reaches, if one time of watering is missed for crops in crucial growth period in Apr. o May (about 15-20 days), the crops reduction is about 30%, the net volume for one time watering about 60m3 /mu and cross volume about 111m3. According to the market price of wheat, one time watering lost of wheat in crucial growth period is 190.8 Yuan, economic benefit about 1.72 Yuan/m3. The long-term mean water supply from upstream reservoirs to middle reaches is 32000000 m3 and the agriculture economic benefit 56000000 Yuan. (3) Analysis on water-reduced river section The Xiaogushan HPP will divert the Heihe River water through a long diversion tunnel, which will form a 11.5km long water reduced section. The The Xiaogushan EIA Group of Gansu Provincial Environmental Science and Design Institute has compared this water-reduced section with the runnel having similar ecological conditions, and found that a discharge of - 11 -  1.6 m3/s can meet the minimum ecological requirement of the water-reduced section. The discharge of 1.6 m3/s was selected after comparing to the downstream Xiliushui runnel. At present, the yearly average discharge of the runnel is 1.5m3/s, which can satisfy the growth of bush fallow and grasses in the gully, and the ecological conditions at the gully is better than the Xiaogushan water-reduced section. Therefore, it is deemed that the biological water supply requirement in the section should be satisfied by this 1.6 m3/s discharge. Except the dry season, the air temperature rises from April and May, and the ice in the river channel will be thawing, which will supplement part of biological water supply. In June - September, the floods come and rainfall concentrate, which will satisfy the water demand for sustaining biological conditions. In October -November, rainfall reduces and river flow reduces. As the herbaceous plants get drooping, thus, the biological water demand is reduced. Therefore, the discharge of 1.6 m3/s for dry season can meet the biological demand in the water-reduced section. To ensure the discharge of 1.6 m3/s for dry season, the EIA Group recommends arranging water release passage in design of the dam. (4) Analysis on impact to habitation of organism The cascade developments on upstream reach of Heihe River will raise the water level in the reservoir areas, enlarge the water surfaces, increase the humidity and reduce temperature difference, which will be favorable for the growth of plants in vicinity of the reservoirs, and provide a better habitat conditions for animals with plenty of food. The reservoirs of the cascade hydropower plants are at high altitude, mostly above El. 2000m, the average temperature of the reservoir water is low (0.40 to14.3E), thus, the hydrobios species is limited and population structure is simple, and quantity of each species is small. Alga is the most popular species found there. After reservoir impoundment, the quantity of predominant alga species in dystrophic water bodies will be reduced a little, and that in moderately nutrient water bodies will be increased a little. (5) Impact to water quality The upstream watershed of Heihe River is of Class I functional zone for water environment. No pollutant is allowed to discharge into the water bodies in construction and operation phases of the project, and the local environmental protection authorities should inspect regularly and irregularly the operation of the environmental protection facilities, so as to ensure the environmental protection measures in the EIA to function well. The small amount of oils that discharged into the water bodies during maintenance of the power plant will not reduce the function of water bodies as a whole. - 12 -  3. Environment Assessment of 35kV and 110kV Transmission Lines 3.1 General ( 1 ) 35kV transmission line The construction scale of Xiaogushan 35kV transmission line is: started from "T" joint of 11# post of Longhe line (1# post of new line) to 35KV substation of Xiaogushan power station, 26.443 km long. In which, new line is 24.443 km, rebuilding line 2.0 km. The line route is shown in Fig.3 o 1. ( 2 ) 11 OkV transmission line The construction scale of 110kV transmission line is: to build two circuits 11OkV transmission line from 11OkV Heihe substation to Xiaogushan step-up substation, wire type LGJ-240, 19.0 km long. Double grounding lines will be set, zinc steel stranded wire on the left grounding line and OPGW communication optic line on the right grounding line. The line route is shown in Fig.3 o 2. 3.2 Regional Environment Along Line Route 3.2.1 Landforms and geology ( 1 ) 35kV power supply transmission line The transmission line route is crossing two landforms dividing as high and middle mountainous region and alluvial plain. The alluvial plain section is from "T" joint to snecked-slope, where the landform is relatively flat, wide, most of desolate land, local farmland at EI.1700 o 2000 m, line length 4.0 km. The alluvial plain is formed by cobble and gravel, sandstone, quartz, granite, metamorphic rock, relative dense - mid-dense, size 5 E 10cm; 1.0 m thick yellow silt soil is covered locally. The high and middle mountainous region is from snecked-slope to Xiaogushan 35kV substation, where is precipitous, most of barren land at EI.2000 o 2930 m, line length 22.5 km. The strata of high and middle mountainous region is of yellowish brown and brick red color sandstone, lilac and shallow gray coarse sandstone, middle layer shape, block structure, fissures developed, about 1.5m surface strongly-weathered and middle weathered for the rest. In which the 2.0km at the north of Xishui township is of yellow silt soil on the surface, about 1.0m thick, o 5.0 m thick pebbles underneath. The basic seismic intensity along the line is o (2 ) 11 OkV power supply transmission line I13 -  Xiaogushan power supply transmission line route is crossing Sunan autonomous county and Zhangye city area of Gansu province. The transmission line is from Xiaogushan outgoing line to Heihe 11OkV substation, the landform along the route is unity, strata simple and geological condition is relatively good. Based on "Earthquake dynamic parameter classification of China" the basic seismic intensity along the line is L , acceleration velocity 0.15g and the earthquake reaction feature period 0.40s 3.2.2 Hydrology condition ( 1 ) 35kV power supply transmission line The project is at Xiliushui water system of Heihe River basin, from Xishui township to Xiaogushan 35kV substation (about 5.2km) over Xishui river for four times. The terrain along the transmission line is relatively high without flood and erosion condition, therefore, the project area does not meet flood and erosion impact. (2 ) 11 OkV power supply transmission line The project is at Heihe water system of Heihe River basin, crossing over for two times at the north of Xiaogushan station and Yinluoxia. The valley at crossing point is narrow, and the transmission line over the valley with one span and Heihe River inside the valley. 3.2.3 Ecological environment ( 1 ) 35kV power supply transmission line The soil type along the transmission line is of cold felty-soil and calcimorphic soil. The felty-soil is mainly distributing on upper part of two sides of valley and calcimorphic soil in alluvial plain. Few anthropogenic alluvial soil are distributing in Xishui township by human cultivation activities. The vegetation in the project area is typical natural steppe, a good winter-spring lawn, and agriculture planting in partial gentle area (mainly at Xishui township) with wheat and oil plants. There is no woods and bush on both sides of hill, few willow, pine and popla planting in Xishui township area. Grass is mainly of Krause's spear grass, purple flower spear grass, flat ear wheatgrass, coverage 30 - 70%, production quantity 65 - 95 kg/mu. w 2Di 11 OkV power supply transmission line The route of transmission line is mainly of mountainous area or huge hill except 2.0km flat area(alluvium deposit) at outgoing line section of - 14 -  substation. The felty-soil is mainly distributing on upper part of two sides of valley and calcimorphic soil in gentle plain. There is no woodland, grassland and agriculture crops along the line; The natural vegetation is mainly of Krause's spear grass, purple flower spear grass, plat ear wheatgrass, coverage 50 450 , with a natural environment landscaping. 3.2.4 Social environment El 1 ri 35kV power supply transmission line Xiaogushan 35kV transmission line is routing in open wasteland, barren mountain, with sparse crowd. Only Bajiaowan village of Xishui township is at 5.2km away to the substation. This village has population of 288, farmland 444mu, lawn area 10275mu, forest land 30mu. Villagers are mainly engaged in the agriculture production and animal husbandry, do not have industrial enterprise, average income per capita is 3800 Yuan/person. There is no historic site and key cultural relic protection unit in this area. Ci 2W 110kV transmission line Xiaogushan 11OkV transmission line is routing in open and barren mountains, without village and population distribution along the line. There is no historic site and key cultural relic protection unit in this area. The social environment is simple and there is no sensitive object and spot by the environment impact. 3.2.5 Land occupation Li 1 El 35kV transmission line This project has 105 posts and towers including 45 straight-line post, tensile post and terminal post; 60 straight-line tower, line-pulling tower and tensile tower. The land occupation is divided into permanent land occupation and temporary occupation. The permanent land occupation is for the base of post, tower and protection facilities, and temporary occupation for the construction. By the calculation, the permanent land occupation is about 16039m2W in which 16000 m2 is for base of tower and protection area and 39 m2 for the base of post; The temporary land occupation is about 2963 mi2. The permanent land occupation is of wasteland and partial herbage site(belongs to Bajiaowan village), in which the wasteland area is 12562 mi2L natural herbage land 3477 M2. Li 20 11 OkV transmission line This project has 100 posts and towers including 83 straight-line post and corner post; 17 straight-line tower, corner tower and terminal tower. By the calculation, the permanent land occupation is about 4629M2Wo in which 4533 M2 is for base of tower and protection area and 96 M2 for the base of post;- The temporary land occupation is about 5465 m2. They are all of wasteland. - 15 -  3.3 Environment Assessment of Construction 3.3.1 Environment assessment in construction period The total construction period of two projects is 12 months, peak construction period 35 persons/day. The construction is basically by manual because the project area is in huge mountain, inconvenient traffic condition and hard for operation of mechanical equipment. By the construction characteristics, the construction for land occupation, ground clearing, excavation and base placement will result different level of impact on and atmospheric environment for the project area. El 1 Fl Analysis of ecological environment Due to the construction of post and tower and land occupation, which will result change of land use and missing of original surface overburden by ground clearing, excavation and treading, and increase of naked land. Firstly, the land use feature occurs certain change of structure of present situation, and easy to cause water and soil loss for excavated area; Secondly, the exposure of deep soil can initiate the change of physical and chemical nature, causing lose of soil fertility, poor of structure, and change of soil microorganism crowd. The damage of protection layer and vegetation of construction area will cause reduction of vegetation, weakening resisting ability of outside environmental of land system, reducing the stability of original ecological system. But the project construction is only for a short period and has temporary and instant behavior, and the temporary land occupation has recoverable features. 35kV transmission line The permanent land occupation of 35kV transmission line is only 0.16hm20 and 941z for the protection area no change of land use; Only 962 m2 land is changed from wasteland and herbage to construction land, which is very little proportion and from long-term analysis, the influence is very tiny and accords with the national construction land requirement. The temporary land occupation is 1 5.60%,for which the surface vegetation will be recovered within 3-5 years after leveling when the project is completed and the influence is also very little for ecological environment. For occupying desolate grass land of felling 22 poplar in Bajiaowan village, the project unit has paid the compensation fee according to the national relevant compensation stipulation and standard, in which 6000 Yuan for desolate grassland and 1200 Yuan for the trees. On certain level, the compensation makes the natural and social environmental influence of Bajiaowan village falling into a minimum level. 11 OkV transmission line The permanent land occupation of 110kV transmission line is only - 16-  0.046hm2 E and 940 for the protection area no change of land use; Only 272 m2 land is changed from wasteland and herbage to construction land, which is very little proportion and from long-term analysis, the influence is very tiny and accords with the national construction land requirement. The temporary land occupation is 54.14%,for which the surface vegetation will be recovered within 3-5 years after leveling when the project is completed and the influence is also very little for ecological environment. (2) Analysis of atmospheric environmental influence During the construction period, the rock blasting and base excavation will result in dust pollution locally. The most area along the line is of mountain, gully, and more excavation for the base of post and tower. According to relevant information, the mechanical rock drilling dust quantity is 4.8g/s (by dry drill) without dust-proof facility, and the dust density in air for long time operation will be 1000mg/ m3, which will cause heavier influence for air quality of the operation area. There are some blasting spots for the two transmission lines, the dust is different when the blasting way and explosives volume is variable. According to the information, the dust quantity of mineral operation is 25 g/m3, the larger size dust will fall in short period after the blasting but size El 10mm dust not easy to fall and suspend in air, which will cause unfavorable influence for ambient environmental (mainly at operation area). 3.3.2 Environment assessment for operation period tl 1 0 Impact on land resources After the completion of 35kV and 11OkV transmission line and leveling of construction area, the surface vegetation will be resumed gradually along with the production operation of project, and the unfavorable influence for land resource will disappear gradually through the recovery of ecological environment. E 201 Impact by pesticide and weed killer The construction area has no farmland and woodland and is of natural environment, very few human activities for ecological environment, therefore, there is no any insecticide and chemical material of weed killer to intervene this area. And according to the plan of Qilianshan National Natural Protection Zone, the line route is not in the plan, therefore, in the operation period after the construction of project there is no way to use any insecticide and weed killer and chemical influence to post and tower base facilities. - 17 -  4. Alternatives Comparison and Analysis 4.1 Comparison of Dam Xiaogushan power station is linked with Dagushan project upstream and Xiliushui project downstream, 11.18km longE head 161mE mean slope 14.4 %.O This section is in " V" shapen rapid current, river surface 30 o 50 m wide. There are 3 dam-sites that satisfy the condition for dam construction, 1# dam-site, 2# dam-site and 3# dam-site. 1# dam-site is located at 0.3km downstream Shilaban gully, 2# dam-site located at 1.8km downstream 1# dam-site, 3# dam-site located at 4.15km downstream 1# dam-site, refers to Fig.4-1 for specific location. 4.1.1 Engineering Features of Dam Selected (1) Dam 1# dam-site is of barrage 2# dam-site gravity dam, 3# dam-site double arched dam, designed by Gansu provincial investigation and design institute, see Table 4-1 for the hydraulic parameters. 3 dam-sites satisfy the requirement of tunnel and road except the hub project, see Table 4-2 for the engineering quantity. The hub structure of 3 dam-sites is: stepped diversion for 1# and 2# dam-site, tunnel diversion for 3# dam-site, diversion discharge 678m3/s. See Table 4 m 3 for discharge and length of diversion tunnel. See Table 4 E 4 for investment of hub, tunnel and road of 3 dam-sites. Table 4-1 Hydraulic parameters of Xiaogushan HPP sites in selection Description Unit 1 # dam site 2# dam site 3# dam site Normal water level /normal tailrace m 2060/1920.5 water level Water level raised m 20 42 60 Total storage Parameters capacity of 104m3 140 1417 4173 reservoir Length of power m 9840 8182.4 5822.4 diversion tunnel Head loss m 19.52 17.73 14.24 Net power head m 119.98 121.77 125.26 Main Dam type Barrage Gravity Arch dam structures Crest elevation 2063.2/2027 2062.5/2010 2062.5/1985 /base elevation - 18 -  Dam height 36.2 52.5 77.5 Crest length/crest 82/5 125/5 207.8/5 width Dam body factor 1.15 0.9 0.25 Number of bottom 2-8x 7 2-7x 8 3-4x 6 outlet (No.El Wx H) Surface outletEl No. 2-1Ox 13 2-1Ox 8 2-1Ox 12 oWx Ho _- Table 4-2 Engineering quantity of Xiaogushan HPP sites in selection Quantity Description Unit 1# dam site 2# dam site 3# dam site Excavation and filling 104m3 5.52 15.43 29.1349 Concrete placement 104m3 4.48 11.91 19.88 Main structure Steel bar t 1521 1580.2 3205 consolidation\curtain 104m 0.35\0.55 0.683\1.57 grouting Length of tunnel/size m 3570.2/6 2360/6 0/6 Rock excavation 104m3 12.9593 8.5664 0 C20 steel concrete lining 104m3 2.8699 1.8971 0 Tunnel Bending of steel bar 104t 0.1722 0.1138 0 Consolidation grouting/backfilling 104m/1 04m2 4.29/2.54 2.84/1.68 0/ grouting Temporary access km 16 3 10 Road_ .________ Refurbishing road km 20 5 5 Table 4-3 Main structure of Xiaogushan HPP at selectable sites Construction way Description Unit 1# dam site 2# dam site 3# dam site Diversion mode m3/s\% 678\20 678\20 678\20 Diversion discharge\flood m3/s\% 133\5 1300\5 standard P Discharge\length m 31 0\805 240\805 of tunnel\size Table 4-4 Investment of Xiaogushan HPP at selectable sites I19 -  No. Description Unit 1 # dam site 2# dam site 2# dam-site 1 Main structures 104Yuan 4420.61 8296.98 12883.4 2 Tunnel 104Yuan 7676 5074 0 3 Permanent road 104Yuan 2440 4190 3035 4 Temporary road 104Yuan 2344 1650 2436 Total investment 104Yuan 1688.64 19214.98 18354.43 Percentage I L 100 114 109 (2) Environment condition of selectable dam sites The geological structure of 3 dam-sites is identical, slate of Silurian system, dense and hard, strong resistance of weathering, no surface wearing on rock and unfavorable breaking structure. See Table 4 [I 5. See Table 4-6 for landform of 1 #, 2# and 3# dam-sites. The surface water of 3 dam-sites is from Heihe and Xiliuhe river, with mean discharge 50.5m3/s. The runoff is mainly from precipitation and snow melting from Qilianshan mountain area, runoff distributed uneven in a year, the most runoff centralized in Jun. - Sept., accounting for 68.2%; water falling period in Oct. - Nov., accounting for 10.5%; winter dry period in Dec.- Mar. the runoff added by underground water, accounting for 9.6%; the water in Apr.- May accounting for 11.7%. The distance for 3 dam-sites in within 1 1.18 km, the runoff quantity is almost the same. Geologic structure and landform of optional selectable dam sites Table 4-5 Description 1# dam site 2# dam site 3# dam site 5 - 8 cm thick 5 - 10 cm thick alluvium pebble and alluvium pebble and gravel layer and Two banks are of Siluriangrvl lyro 6-8mspewh Rock type system slate, developed in gravel layer on 6-18cm slope wash foliation mode. valley and left bank, on riverbed and two foliation mode. Silurian system banks, Silurian slate for the rest system slate for the rest hard and dense, good * hard and dense, . developed in weathering resistance, no good weathering foliation mode, good strongly-weathered layer in resistance, no weathering Rock surface strongly-weathered resistance, no character no fracture structure in layer in surface strongly-weathered dam-site area, only local thin no mayor fracture layer in surface layer crushed stone on the left structure in dam no mayor fracture bank, overburden 10cm thick area structure in dam - 20 -  area Table 4-6 Landscaping of optional dam-sites 1 # dam site 2# dam site 3# dam site river surface at dam * river straight at dam section 40m wide C at section, river surface 52m 39m wider in v a m shape El.2040.3m wide S in " v" shape slope at two banks gentle at upper part and steep at . . rock exposed, left bank slope lower part, upper slope 40 hill body steep, no major 58E 620 E: right bank slope 44 5 50