RP174V. 3 July 2003 Foreword I. Task Description Napo Township, Tianyang COunry, Public Disclosure Authorized Naji Navigation Complex is placed by Naji Village, which is about 38km downstream of Baise City. The Complex is multi-purposely built for water resources utilization, majoring in navigation, giving attention to power generation, irrigation and other aspects. It will also act as a counter-regulation reservoir for Baise Hydraulic Complex. It is on the fourth step to be built in the Overall Planning of Yujiang River. The normal water storage level of the reservoir is 115m, backwatered to the lower approaching channel of Baise Hydraulic Complex, which is in the upstream. The total length of the reservoir is about 56km, and the total capacity is 103 million m3 . The reservoir area compromises Youjiang District of Baise City and Tianyang County, the geographic coordinate is round east longitude 23°44' - 23°53', north latitude 106032' - 106 47', as detailed in the Location Map (Drawing 1). Up till now, the engineering geological investigation and geological hazard evaluation for completed. Whenever taken into account Public Disclosure Authorized the preliminary design of the Project has been that there are rich mineral resources in the reservoir area and the areas along the banks of the reservoir, in purposes of guaranteeing the safety in the mining production on both banks of the reservoir area as well as the normal operation of the reservoir after the completion of the Project, Nanning Non-ferrous Metal Foundation Work Survey Institute has undertaken the investigation and study on the relationship between the coal mines and the reservoir, as entrusted by Guangxi Xijiang Waterway Construction and Development Co. Ltd., and as required by the World Bank in its faxed dated June 11 and June 18 of 2003 as well as the Third Meeting of the Dam Safety Panel held on May 25 of 2003. In accordance with the Investigation and Research Program, the aims and tasks of the task include the following: Public Disclosure Authorized a. To investigate and find out the distribution of mineral resources and the distribution of production activities in the reservoir area and the areas around the banks, to find Out the relationship and the functions among the state-owned coal mines, the township coal mines, the individual coal mines and the illegal coal mines; b. To confirm the distance between the reservoir and the safety operation of the coal mining activities, to check for the potential coal mine resources in the reservoir area; c. To investigate and find out the characteristics of the stratum lithology and the faulted structure in the reservoir area and the area around the banks, the characteristics of hydrogeology and the engineering geology in the coal mine areas, as well as the relationship between the safety in reservoir operation and the safety in coal mine production; Public Disclosure Authorized d. To investigate and find out the influence extent of the coal mining in the reservoir and the areas around the banks to the safety in reservoir operation, as well as the influence extent of the reservoir to the mining activities, so as to forecast the potential geological hazards such as the inundation and immersion as well as the leakage of the reservoir; I CFnLF NWP'Y e. To investigate the influence of the amplitude of the water in the river for the past years on the exploited mines, for instance, the history of coal mine flooding because of the swelling of the river; f. To give a comprehensive evaluation on the above-said influence factor for the potential reservoir water storage and the coal mining, as well as the potential geological hazards, and to propose a scientific and reasonable solution and measures. The Special Report on the Relationship between Coal Mines and the Reservoir for Naji Navigation Complex, including the main text and the attached drawing, is provided at the last, so as to offer an external and true evaluation for the Client and related departments. II. Process of the Task The task commenced on June 20, 2003. On the basis of related information collection on the reservoir area and the peripheral foundation geology, mineral geology, hydrogeology and engineering geology, the field investigation starts on June 26, 2003, and finished on July 1. The indoor clear up, the compilation of the report and the attached drawings are preliminarily finished by the first half of July. The Special Report on the Relationship between Coal Mines and the Reservoir, including the main text and the attached drawings, was provided to the Client on July 11. The main quantities of the task are detailed in Table 1-1. Main Quantities of the Task Table 1-1 Task Quantity Scale Geological Investigation for the Minerals along the Banks 60km' 1: 10000 of the Reservoir (field sketching) Worked-out Area Investigation along the Banks of the 40km 1: 10000 Reservoir (field sketching) Hydrogeological Investigation along the Banks of the 100km 1: 10000 Reservoir (field sketching) _ Engineering Geological Investigation along the Banks of the 60kmi 1: 10000 Reservoir (field sketching) I In addition, we would like to extent our sincere thanks to the officers and experts from the Fourth Survey Branch of Guangxi Geological Investigation Institute, the Information Center of Guangxi Land Resources Department, the Administration Bureau for Small Coal Mines of Guangxi, Baise Land Resources Bureau, Tianyang Land Resources Bureau and Gonlou Branch of Youjiang Mine Bureau, who have offered assistance and institutions during the information collecting, field investigation and report preparation of the task. 2 Chapter 1 Reservoir Geology, Hydrogeology, Engineering Geology Section 1 Reservoir Geology I. Stratum lithology There are Carboniferous, Permian, Triassic, Eocene, Quaternary stratum in and around the reservoir area. Tertiary and Quaternary strata distribute most principally. Here is description of the lithology. 1. Quaternary (Q) Quatemary stratum in the reservoir area can be distinguished as Holocene alluvium (Qa1 4 h) and Pleistocene alluvium. (Qa3p ) a. Pleistocene alluvium (Qal4 h) It is mainly located along the banks of Youjiang River. The banks are composed by neoteric floodplain (Q 4h2) and the first terrace by the river (Q al4h' ) . Lithology is yellow, lark silt or clay silt, and gray, caesious, yellow, lark sand and scree gravel. The thickness is 0.7-33.1m. b. Pleistocene alluvium. (Qalp) It is mainly distributed along the banks of Youjiang River. They are composed by the second, third and fourth terrace by the river banks. The terraces are in dualistic structure. The top is brown silt clay in plastic or hard plastic form. The lower is sand and scree gravel. The thickness is 43-84m. 2. Eocene (E) It is the principal stratum in the reservoir area, which is divided into Pliocene Dongjun Group (E 2d) , Nadu Group (E 2n) , Baigang Group (E 2b) , Oligocene Fuping Group (Elf), and Jiandu Group(Elj). Lithology is mudstone, silt mudstone, soil sandstone, silt sandstone, sandstone, gravel sandstone. Eocene Nadu Group (E 2 n), Baigang Group (E 2b), Oligocene Fuping Group (E3f) are the principal coaly stratum of Baise coalfield. The coaly stratum are 10 - 40, 2 - 7 available. The total thickness is over 600-3000m. 3. Tertiary (T) It distributes around basin periphery, composed by Miocene Lamu group (T21), Baipeng Group (T 2 bf) , Paleocene Luolou Group (T 11) a. Miocene Lamu Group (T21) 3 It is celadon thin or thick calcrete, sand mudstone, quartzite, calcicolous mudstone, calcicolous silt sandstone. The thickness is 8 6 8-1697m. b. Miocene Baipeng (T2b]) It is thin or mid-thick calcrete mudstone, silt quartzite, calcicolous silt sandstone. The thickness is > 1900m.. c. Paleocene Luolou Group (T1 l) It is gray -dark gray thin or mid-thick calcicolous mudstone, sand mudstone and gray rock. The thickness is 58-277m. d. Permian (P) It distributes in the east-south reserVoir, where is south of Napo county. The scope is small, including Upper Heshan Goup (P 2h) and Lower biologic Reef (Pbls) (i) Upper Heshan Goup (P 2 h) It is lark folium mudstone , dark gray folium argillite, argillite mudstone, ash rock and lapillus. The thickness is> 155m. (ii) Lower biologic Reef (Pbls) It is gray and dark gray thick cascade biologic crumbs. The thickness is 15-389m. e. Carboniferous upper (C 2 ) Carboniferous upper is distributed in the east-south reservoir, where is south of Napo county. The scope is small, including Maping Group (C2pm) and Huanglong Group (C2 h) (i) Maping Group (C 2pm) It is fleet gray and gray thick cascade lime, biologic crumb lime, flint lime, argil. The thickness is 137-352m. (ii) Huanglong Group (C 2h) It is fleet gray and gray thick cascade lime, biologic crumb lime, oolite. The thickness isll12-138m. II. Geologic Formation 4 a. Regional Geologic Formation The reservoir locates Xinlin-Baise ruche, which is part of the south-china quasi-mesa Youjiang River renewed geosyncline. The Youjiang River great rupture affects main formation. Part of the rupture, Yongle-Tianyang section, passes from north to west 7-8km from north of the reservoir. The pressing- tensing rupture trend from north-east of north-west with obliquity of 60° -80° and trend of NW310° - 3200 .Some wide crack along the rupture is over 100 m width. The rupture divide the stratum below upper Paleozoic with depth of 10-15km. It is not deep rupture. The period is yinzhi-yanshan in Cenozoic action. Youjiang River great rupture affect the inclined basin and following formation. Details are in formation program chart 1-1. b. Geologic Formation in Reservoir Area Reservoir locates in Baise Basin, which is a constructional fault basin, strip tension in orientation 2900 , 50km total length, 7-13kni width, 25km width within reservoir.