l, A D6 500 kV TRANSMISSION LINES FrOP GREA TXEr BA.N-GKO^iK ARE)h E-235 VOL. 26 FINAL DRAFT ENVIRONMENTAL. RL POR E Michtelle. Clark 16 Ociober 1996 EGAT - INVESTMENT PROGRAM SUPPORT PROJECT (WORLD BANK PARTIAL CREDIT GUARANTEE) Contract Number 4719-30-5803-EGAT-BKK-EH!V-CS Consultancy Engineering Services 500 kV TRANSMISSION LINES FOR GREATER BANGKOK AREA FINAL DRAFT ENVIRONMENTAL REPORT Michelle Clark 16 October 1996 Contract Number 4719-30-5803-EGAT-BKK-EHV-CS Consultancy Engineering Services 5/5 CONTENTS Chapter 1 Introduction 1 Chapter 2 Design Options 5 Chapter 3 Landscape and Visual Impact 12 Chapter 4 Socio-economic Aspects 17 Chapter 5 Cultural Heritage 22 Chapter 6 Land Use 25 Q Chapter 7 Water Quality 33 Chapter 8 Flora and Fauna 40 Chapter 9 Electric and Magnetic Fields 47 Chapter 10 Audible Noise 53 Chapter 11 Electromagnetic Compatibility 56 Chapter 12 Conclusions 59 APPENDICES Appendix A References 63 Appendix B List of Abbreviations 64 Appendix C Glossary of Terms 65 SCHEDULE OF TABLES Table 4.1 Key Informants for Socio-economic Field Survey Table 4.2 Community Baseline Data Table 6.1 Land Use Categories along the Proposed 500 kV Transmission Lines Table 7.1 Waterways Potentially Affected by the 500 kV Transmission Line Development Table 7.2 Results of TEAM Surface Water Quality Survey (9 February 1996) Table 7.3 MOSTE Surface Water Quality Classification Table 7.4 MOSTE Surface Water Quality Classification Table 8.1 Species and Abundances of Phytoplankton Table 8.2 Species and Abundances of Zooplankton Table 8.3 Planktonic Organisms as Indicators of Water Quality Table 8.4 Species and Abundances of Benthic Organisms Table 8.5 Benthic Organisms as Indicators of Water Quality Table 9.1 Predicted Electric Field Strengths Table 9.2 Predicted Magnetic Field Strengths 9 SCHEDULE OF FIGURES Figure 1.1 Existing 230 kV Lines (to be Replaced) in the Greater Bangkok Area Figure 1.2 Proposed 500 kV Lines in the Greater Bangkok Area Figure 2.1 Vertical 2x2x2 Portal Tower Fig, ,re00 °.° Hrzna 3 o r -:e Figure 2.3 Traditional Vertical Tower with Single Steel Pole Construction Figure 2.4 Traditional Vertical Tower of Steel Lattice Construction Figure 2.5 Comparison of Final Proposed design with EGATs Existing 500 kV Design Figure 3.1 Comparison of Proposed 500 kV Tower and Existng 230 kV Tower Figure 5.1 Location of Known Archaeological Sites in the Greater Bangkok Area Figure 6.1 Definition of Landscape Elements Figure 6.2 Landscape along Bangkok Noi - Sai Noi Route Figure 6.3 Landscape along Sai Noi - Rangsit Route Figure 6.4 Landscape along Rangsit - Chaeng Watthana Route Figure 6.5 Landscape along Nong Chok - On Nuch Route Figure 9.1 Assumed Phasing for Proposed Quad Circuit 500 kV Line Design SCHEDULE OF PHOTOMONTAGES View 3.1 SCHEDULE OF PHOTOGRAPHS Photo 3.1 Existing 230 kV Transmission Line Crossing Typical Rural Land Photo 3.2 Existing 230 kV Transmission Line Crossing a Real-Estate Project Photo 3.3 Muang Thong Thanee Complex CHAPTER 1 INTRODUCTION BACKGROUND 1.1 The economic growth rate for Thailand during the 61h and 71 National Economic and Social Development Board's (NESDB) Plan Periods (1987- 1991 and 1992 - 1996) has been very high. It is expected that this high economic growth rate will continue, at least during the 81 plan (1997 - 2001). 1.2 One of the effects of this economic growth has been a dramatic increase in electricity demand, especially in the Greater Bangkok Area. This increase in electricity demand has resulted in a requirement for the Electricity Generating Authority of Thailand (EGAT) 'to develop a 500 kV transmission system for this area. K') 1.3 EGAT contracted the National Grid Company plc (NGC) to design these 500 kV transmission lines, in conjunction with two local partners: TRANSEC and TEAM. TRANSEC are a transmission system engineering consultancy, while TEAM are an environmental consultancy. TEAM therefore provided much of the information for the environmental study. PROJECT DESCRIPTION 1.4 The Project involves replacing four existing sections of 230 kV transmission line with 500 kV transmission lines. The four sections (shown in Figures 1.1 and 1.2) and their lengths are listed below: a Bangkok Noi - Sai Noi 29.4 km * Sai Noi - Rangsit 24.7 km * Rangsit - Chaeng Watthana 7.4 km * Nong Chok - On Nuch 17.9 km All the above is to consist of double circuit transmission lines, apart from 1.8 km of the Nong Chok-On Nuch section which will be quad circuit. This will form the line entry to On Nuch Substation. 1.5 EGAT require the new 500 kV transmission line system to be constructed as far as possible along the existing 230 kV transmission lines' alignments using the same Rights- of-Way. The total width of a 230 kV Right-of-Way is 40 metres, ie a corridor of 20 metres either side of the route centre-line. SCOPE OF ENVIRONMENTAL REPORT 1.6 The objectives of the study are firstly to identify the potential environmental impacts due to the Project and, secondly, to recommend mitigation measures to alleviate any adverse impacts. The environmental areas of concern which have been addressed in this report are as follows: 1 * landscape and visual impact * cultural heritage * land use * water quality __ _ * flora and fauna (particularly aquatic ecology and impacts on birds) :s- ~ * effects on human beings (including safety, socio-economic impacts, electric a,.d -magnetic field effects and audible noise) * electromagnetic compatibility 1.7 Effects on climate and air quality were considered, and rated as insignificant. 2 230 kV double circuit Sai Noi twin 1272 MCM Rangsit 230 kV double circuit ft 1l single 127;2 MCM Chaeng Watthana 230 kV double circuit single 1272 MCM Nong Chok 230 kV double circuit twin 1272 MCM Oni Nuch Bangkok Noi Chao Phraya Figure 1.1 Existing 230 kV Lines (to be Replaced) In the Greater Bangkok Area 500 kV double circuit Sal Nol quad 1272 MCM Rangsit 500 kV double circuit quad 1272 MCM Chaeng Watthana 500 kV double circuit Nong Chok quad 1272 MCM 500 kV double circuit quad 1272 MCM 500 kV quad circuit quad 1272 MOM On Nuch Bangkok Nol Chao Phraya Figure 1.2 Proposed 500 kV Lines in the Greater Bangkok Area CHAPTER 2 DESIGN OPTIONS INTRODUCTION 2.1 The parameters driving the design of the new 500 kV transmission lines were as follows: * the restricted Right-of-Way, resulting in a need for a compact line design, both from mechanical {eg conductor blow-out) and electrical (eg EMF) perspectives, * environmental concerns (mainly visual impact), * ease of construction, operation and maintenance, * cost of construction, operation and maintenance. 2.2 Four preliminary tower designs were considered initially: . > * vertical 2x2x2 portal tower of steel lattice construction, * horizontal 3x3 portal tower of steel lattice construction, * traditional vertical tower of single steel pole construction, * traditional vertical tower of steel lattice construction. These are shown in Figures 2.1 to 2.4. ASSESSM ENT 2.3 The vertical 2x2x2 portal tower has the advantages of low EMF levels due to reduced phase separation, longer spans (ie fewer towers and reduced visual impact ) and reduced foundation loads (ie smaller foundations and reduced ground disturbance). However, these advantages are outweighed by the size of the stabilising guys required (ie increased ground-take) and problems with hot line maintenance where new procedures would be required. This tower design was eventually ruled out when EGAT requested the standard ground clearance be increased from 11 metres to 16 metres. 2.4 The horizontal 3x3 portal tower also has low EMF levels due to reduced phase spacing; in addition, it is possible to increase the ground clearance of this design without exceeding the height of conventional towers. However, this design would have introduced even more significant problems for hot line maintenance as well as requiring sizeable stabilising guys, beams and columns. For these reasons, this design was also dismisssed. 2.5 The traditional vertical tower with a single pole construction would also allow reduced EMF levels due to phase compaction and longer spans if 'V" insulation were used. However, this design also has maintenance difficulties and large, expensive foundations which may disturb land drainage. Tthese aspects of the design eventually ruled it out when EGAT requested the standard ground clearance be incraesed from 11 metres to 16 metres. 2.6 Therefore, the preferred transmission line design became a conventional vertical steel lattice tower. This design was optimised to produce a tower which is lighter and cheaper than EGAT's existing 500 kV tower design, while having increased span capacity (reduced visual impact), reduced foundation loads (less ground disturbance) and reduced EMF levels due to phase compaction. 2.7 The final proposed double circuit 500 kV tower design is shown in Figure 5, next to EGAT's existing 500 kV design. CONCLUSION 2.8 Four basic design concepts were considered before the conventional vertical steel lattice tower was chosen. This was preferred because of its maintainability, reduced foundation loads (less ground disturbance for smaller foundations), longer span capacity (reduced visual impact due to fewer towers) and reduced EMF levels (due to phase compaction). Figure 2.1 Vertical 2x2x2 Portal Tower / VT~~ -7 Figure 2.2 Horizontal 3x3 Portal Tower , :d "(',K Figure 2.3 Traditional Vertical Tower with Single Steel Pole Construction IN) PZE P P R <9 Figure 2.4 Traditional Vertical Tower of Steel Lattice Construction IC) Figure 2.5 Comparison of Final Proposed Design with EGAT's Existing 500 kV Design Li i-I 0 Li -1 ii;i. 'tt"|!S li//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ s~~~~~~~~~~~ 'C' CHAPTER 3 LANDSCAPE AND VISUAL IMPACT INTRODUCTION 3.1 The aim of this chapter of the Environmental Report is to describe the existing landscape through which the proposed 500 kV transmission lines would pass. The potential landscape and visual impacts caused by the alterations to the network in the Greater Bangkok Area are also assessed. ASSESSMENT Landscape 3.2 The land along the Bangkok Noi - Sai Noi route is mainly open and agricultural in nature. Therefore, transmission lines can be observed over a long distance. There are some real-estate projects in the vicinity, the land in the Right-of-Way being used as 'open space", ie parks, lakes or treatment lakes/oxidation ponds (Photos 3.1 and 3.2). 3.3 Between Sai Noi and Rangsit, the land consists of agricultural land (paddy fields and veg;,etable plantations), dispersed housing and one major industrial area. The land is generally flat, and so transmission lines can again be seen from great distances. There are also a number of temples along this section of the Project (see Chapter 5), and a crossing of the Chao Phraya river. The existing two 230 kV towers on either bank are painted yellow and white to aid visibility; all the remaining towers are grey. Finally, there are many khlongs in this area; these are used for transportation and irrigation. 3.4 The transmission line route between Rangsit and Chaeng Watthana runs parallel with Khlong Prapa. The majority of this line passes through vacant land, some agricultural areas and low density residential areas. Near Chaeng Watthana substation, the transmission line passes through Muang Thong Thanee, a high-density residential complex which includes some office buildings (Photo 3.3). People from Muang Thong Thanee have their view of the sunrise crossed by the existing 230 kV transmission lines. 3.5 Finally, the Nong Chok - On Nuch transmission line passes through a mainly agricultural area comprising chicken farms, fish culture ponds and grass fields (which are for sale). There are also some housing projects, and khlongs are the major transportation means in this area. In the future, this line route will have to cross a major road interchange (Tab Chang) which is currently under construction. The height of towers in this area will consequently have to increase, and there will be a resultant increase in visual impact. Visual Impact 3.6 Transmission lines can form relatively strong visual features in low-lying and flat landscapes. The potential impacts occur when a transmission line (or any part of a line, such as a tower) intrudes into the view of receptors. The main visual receptors for this Project would be residential. 1 2 3.7 The existing 230 kV transmission lines are judged to have a minor visual impact because they pass through mostly vacant and agricultural land in the suburbs of Bangkok. The towers are far apart, and from a long distance the transmission lines can barely be perceived because their colour is compatible with the sky and background. It is generally agreed that the view of a transmission line is considered insignificant at a distance of greater than 2 km. 3.8 Interviews with key informants (see Chapter 4) revealed that residents did not feel they suffered from any visual impact because the existing lines had been there for a long time and they were 'familiar" objects. 3.9 The proposed 500 kV line design is superficially very similar to the existing 230 kV line designs. This is beneficial because local residents accept the existing structures and are unlikely to be concerned by the fact that the proposed line design has slightly larger towers (Figure 3.1) and more conductors. Distant views of the transmission lines will be almost unchanged. 3.10 The visual impact of the proposed new 500 kV transmission lines compared to the existing situation would be slightly greater, but would not be as significant as the visual impact of constructing a new line in a landscape without transmission equipment. It is therefore better to increase the capacity of the existing network by replacing existing lines than by building more, new lines. MITIGATION 3.11 In the flat, open landscape typical of the area, transmission lines are often highly visible. The facts that the proposed 500 kV towers are slightly larger than the existing towers, and that the 500 kV lines would have more conductors than the 230 kV lines (four compared to either one or two), are compensated for by the superficial similarity of the proposed line design to the existing. Residents are familiar with these structures and accept them as part of the Greater Bangkok Area landscape. 3.12 Given their height, any screening to mitigate the visual impact of the towers (particularly their upper extents) is difficult. Any such screening must be positioned close to the receptor and, as such, would block views of the wider landscape. It is therefore not considered appropriate to suggest screening, such as general planting, for this Project. 3.13 TEAM's visual impact experts recommend that a light colour be used for the towers to minimise their visibility when viewed against the background environment, and the sky in particular. This means that the towers could be left galvanised or painted grey. CONCLUSIONS 3.14 The proposed 500 kV transmission lines would pass through mainly open, agricultural or residential areas. This means that they would be visible over a considerable distance (up to 2 km if there are no intervening features). However, distant views of the 500 kV lines would be almost indistinguishable from views of the existing 230 kV lines. These are accepted by the community as a familiar part of the landscape, and therefore the visual impact of the Project woUld be small, and significantly less than the visual impact of a project which introduced a new line into a landscape without transmission equipment. -Photo 'A1: Existing ')30 k'J Transm.ssion Line C.03ss.ng Typica,l Rural Lancl Photo 3.2: Existing 230 kV Transmission Line Crossing a Real-Estate Project ,/ I4 Photo 3.3: Muang Thong Thanee Complex 15 Figure 3.1 ComDarison of ProDosed 500 kV Tower and Existing 230 kV Tower oooc 00" MOL COOK ) _ff2 -~~~~~~~~~~~~~~~~~~~~"9 WaV OXCK9f .r-X4f !S~~~~~~~~~~~~~~~~~ CHAPTER 4 SOCIO-ECONOMIC ASPECTS INTRODUCTION 4.1 Potential socio-economic impacts arising from the dismantling of the existing 230 kV lines and construction and operation of the proposed 500 kV transmission lines were identified. The study considered the occupations, health, recreation and general living conditions of people living close to the transmission lines. Public attitudes towards the Project were also investigated. ASSESSMENT 4.2 - - Communities in the study area were identified from topography and land-use maps overlaid with administrative maps. This work was confirmed by the field-work. Data was then collected from two sources: = desk study: related documents were studied and analysed, eg subdistrict (Tambon) population records from the Department of Local Administration, and research reports on urban planning, marketing and law. * field study: key-informants in various communities were interviewed to obtain their views about the Project and to discover their peopies' attitudes toward the project. Study Results Documentary Review 4.3 By taking topography and land use maps of the study area and overlaying them with the administrative maps, it can be seen that the four sections of existing 230 kV transmission line pass through many subdistricts of Bangkok, Nonthaburi and Pathum Thani (see Table 4.1). Most areas adjacent to the existing Rights-of-Way for Bangkok Noi - Sai Noi, Sai Noi - Rangsit and Nong Chok - On Nuch are paddy fields, while the land adjacent to the Rangsit-Chaeng Watthana Right-of-Way is mostly idle. There are few communities adjacent to the transmission lines. These have been divided into three categories; rural or agricultural communities, semi-rural traditional communities and housing project or urban communities. Field Data Collection 4.4 TEAM interviewed six key informants on 21 and 22 February 1996. Two of these key informants work for or own housing projects, while the others are community leaders. The key informants also relayed concerns from their villagers. Their details are presented in Table 4.1. Baseline data for the potentially affected communities are presented in Table 4.2. 4.5 Potential problems and impacts reported by the key informants relate to both the construction and the operational periods of both the existing 230 kV transmission lines and the proposed 500 kV transmission lines. They can be summarised as follows: 1-7 * Temporary dikes of paddy fields and fish ponds in the Right-of-Way were damaged by construction equipment and vehicles during the construction of the existing 230 kV transmission lines (village head of Ban Lam Nok Faek). * TV interference from the existing lines already affects the villagers' TV reception, particularly those living close to the transmission line. This TV interference is more frequent durinc the rains or damp (hiah humiditv\ nenrods (I(risada Nakhon 18 and Ban Saeng Bua Thong). This subject is covered in detail in Chapter 11. * The electric field from the existing line apparently causes fluorescent light bulbs to be brighter or causes them to light automatically during the rains or damp periods (Ban Saeng Bua Thong). * A concern that reduced ground clearance may obstruct community development or construction work in the area (Krisada Nakhon Housing Project 18). * The visual impact of the transmission lines indirectly affected the real-estate business of the Ban Saeng Bua Thong housing project. The Krisada Nakhon 18 housing project managed to mitigate this impact by using the area in the Right-of- Way for recreation (a narrow lake). Consequently, the housing units closest to the lake (and therefore also the existing transmission line) had been chosen first by customers. - ) * Residents are concerned about danger when commuting across the Right-of- Way, especially during rain or damp periods (Ban Saeng Bua Thong and Ban Khiong Nai So). 4.6 In spite of the concerns listed above, all the key informants agreed with the proposed 500 kV transmission line project. The reasons for this can be summarized as follows: * The 500 kV project will be able to transmit electrical power efficiently and adequately for a consumption which has increased continuously. * fThe project is necessary for economic growth and development of Thailand. 4.7 Most respondents' perception of the impact of the 500 kV transmission lines as compared to the 230 kV lines was that the negative impacts would increase slightly because the Rights-of-Way were remaining 40 metres wide. However, the key informant from Krisada Nakhon 18 was worried that residents living close to or commuting across the Right-of- Way may be endangered by the higher voltage and also that the TV interference would occur more strongly than at present. 4.8 The key informants made some suggestions for implementation of the 500 kV Project: * The vertical conductor-to-ground clearance should be greater than the existing line and according to international standards. * A public relations program should be undertaken to inform farmers and/or agriculturalists who have land within the Rights-of-Way to avoid negative impacts from and to the 500 kV Project during construction. This should occur 3 to 4 months in advance of construction for paddy fields and not less than 1 year before construction for fish ponds. * The transmission line towers and conductors should be visible from a long distance. * The transmission line towers and conductors should be insta!led carefully in order to ensure the safety of both residents and workers. Zr .~ Potential Impacts Construction Period 4.9 Most of the areas which the existing 230 kV transmission lines pass through are agricultural (especially paddy fields) and so the majority of affected people are farmers or agriculturalists. Construction work may disturb their daily living, interrupt their farming activities and damage their crops. The main activity which is likely to generate those impacts is erecting new 500 kV towers at new positions. 4.10 In addition, the ability of residents to travel may be affected if their access roads cross construction areas. 4.11 Another possible impact during construction is due to conflict between residents and the Project's officers and workers. This problem may stem from: * affected people having no information or understanding about the Project. - affected people not receiving adequate consideration and/or fair compensation. * the Project's officers or workers behaving improperly. Operational Period 4.12 There was a feeling that residents living adjacent to or commuting across the Rights-of- Way would be more worried because of the voltage increasing from 230 kV to 500 kV. The fact is that the proposed 500 kV transmission lines will still be safe because they will be designed and built to international safety standards. Sufficient clearance would be provided to enable the land Lunder ant near to the lines to be used nnrmarly. Hwn ever, care is always needed when carrying long ladders or irrigation pipes or using high machinery under the lines. 4.13 Real-estate developments close to the Rights-of-Way may have difficulty marketing properties in the vicinity of transmission lines because customers generally dislike the .alien" structures and worry about danger. However, there are already 230 kV transmission lines and these have a similar impact to that of the proposed 500 kV transmission lines. The incremental impact due to the change from 230 kV to 500 kV would be minimal. MITIGATION 4.14 Measures taken during the works and controlled by the contract for the work would seek to minimise disturbance and damage. These measures include protection of watercourses and reinstatement of damage such as accesses, gates, fences and dykes. Assets and crops or trees which are damaged by the construction work should be adequately compensated for. Where the farmer would prefer to carry out his own reinstatement and be reimbursed by EGAT, this could be arranged. 4.15 Where roads would be crossed by construction of the new lines or dismantling of the existing lines, all suitable precautions should be taken including the use of safety equipment and appropriate signage to drivers warning of any hazard. 4.16 If complaints are received, a prompt response should be provided. The Project's officers and workers should maintain a good working relationship with the local people. 4.17 Residents should receive reliable information about the Project, including details of the Project aims and timescales, the possible impacts and the mitigative measures which are to be undertaken. Concerns about increased danger from the higher voltage transmission lines would be addressed by a public education programme. 4.18 Problems associated with real-estate developments already exist due to the presence of the existing 230 kV transmission lin es. EGATs decision to increase the standard ground clearance required from 11 metres to 16 metres should allay concerns over interference with community development or construction work. The additional impact due to the proposed 500 kV transmission lines is therefore minimal, and no mitigative measures are proposed. CONCLUSIONS 4.19 Impacts during the construction period mainly consist of disturbance to farming activities -. in the Rights-of-Way. This disturbance can be minimised by maintaining good communication with affected landowners and considerate working practices. 4.20 Concerns during the operational period mainly relate to safety issues. Sufficient clearance would be provided to enable the land under and near to the new 500 kV transmission lines to be used normally. However, care is always needed when carrying long ladders or irrigation pipes or using high machinery under any overhead transmission lines. 20 Table 4.1: Key Informants for Socio-economic Field Survey Line Section Key Informant Location Bangkok Noi - Sai Noi Chief of Social Facilities Krisada Nakhon 18 Housing Project Division Community Leader Ban Lat Kra Chet, Village No. 6, Bang Ku Rat Subdistrict Sai Noi - Rangsit Owner Bang Saeng Bua Thong Housing Project, La Harn Subdistrict Village Head Ban Kroen, Village No.1, Bang Kra Dee Subdistrict Nong Chok - On Nuch Village Head Ban Lam Nok Faek, Village No.10, Saen Sab Subdistrict Village Head Ban Khlong Nai So, Village No. 20, Minburi Subdistrict Table 4.2: Community Baseline Data Category Community Number of Households housing project Krisada Nakhon 18 300 Ban Saeng Bua Thong 125 agricultural Ban Lat Kra Chet 77 traditional semi-rural Ban Kroen 228 Ban Lam Nok Faek 36 Ban Khlong Nai So 90 A-21 CHAPTER 5 CULTURAL HERITAGE INTRODUCTION 5.1 The known archaeology and cultural heritage of the study area is outlined and the possible impacts discussed. Since the proposed 500 kV development will be within the Rights-of-Way of the existing 230 kV transmission lines, there will be no significant effect on cultural heritage other than small changes to the existing visual impact (as described on Chapter 3) and a small possibility of disturbing archaeological remains. ASSESSMENT 5.2 During the last week of February and the first week of March, 1996, field surveys were conducted by TEAM along the four existing 230 kV transmission lines which will be replaced by the proposed 500 kV transmission lines. In addition, a desk study of archaeological sites in the Greater Bangkok Area was also carried out. The objective of the surveys was to identify existing cultural or historical sites in the vicinity of the Rights- of-Way. Temples and MosQues 5.3 The following temples and mosques were identified in within a corridor of 1 km either side of the centre-lines of the existing 230 kV transmission lines: * Wat Sai Noi (about 600 m to the east of Bangkok Noi - Sai Noi). * Wat Bang Khu Lat (about 900 m to the west of Bangkok Noi - Sai Noi). * Wat Bang Waeg (about 300 m to the east of Bangkok Noi - Sai Noi). * Ban Lam Ri Mosque (about 600 m to the south of Sai Noi - Rangsit). * Wat Saphan Sung (about 300 m to the south of Sai Noi - Rangsit). * Wat Nam Won (about 700 m to the north of Sai Noi - Rangsit). * Wat Chinwararam (about 500 m to the south of Sai Noi - Rangsit). * Wat Kroen (adjacent to Sai Noi - Rangsit). * Wat Daowadung Bon (about 400 m to the south of Sai Noi - Rangsit). * Wat Na Wong (about 900 m to the east of Rangsit - Chaeng Watthana). * Wat Weruwanaram (about 1 km to the east of Rangsit - Chaeng Watthana). Wat Mai Lam Nok Khwaek (adjacent to the Nong Chok - On Nuch). * Wat Thong Samrit (about 800 m to the north of Nong Chok - On Nuch). * Wat Pak Bung (about 600 m to the south of Nong Chok - On Nuch). * Wat Lat Bua Khao (about 700 m to the east of Nong Chok - On Nuch). - * Wat Damrongsatthatham (in front of On Nuch Substation) * Thab Chang Mosque (about 800 m to the northeast of Nong Chok - On Nuch). 5.4 Only two temples are located adjacent to the existing 230 kV transmission lines, namely Wat Kroen and Wat Mai Lam Nok Khwaek. At these sites, the existing 230 kV transmission line can be seen over the temples as a component of their view. For other temples and mosques within 1 km of the centre-line, the transmission lines and supporting structures could not be clearly observed within their visual context. .TX2 Archaeol-ciy 5.5 There were no archaeological findings reported during construction of the existing 230 kV transmission lines, and no findings have been recorded within the existing Right-of- Way. The nearest archaeological evidence was found in the heart of Bangkok, at Ko Rattanakosin and Krung Thonburi (see Figure 5.1). This consisted of ancient cannons andu boats. 5.6 Potential disturbance to archaeological remains only occurs during construction activities; there would be no impact due to the operation of the proposed 500 kV transmission lines. MITIGATION 5.7 For the majority of the cultural sites identified, the proposed transmission lines will not be clearly observable within their visual context and so no mitigation measures are proposed. For the two temples which are adjacent to the proposed 500 kV lines, the - presence of the existing 230 kV lines means that any additional visual detriment will be small. 5.8 The project area is a long way from known archaeological finds; it is therefore unlikely that any site of archaeological importance will be disturbed by the construction activities. In addition, a significant percentage (between 23 and 32%) of the proposed 500 kV towers will be sited over the foundations of the existing 230 kV towers (see Chapter 6). This will minimise the amount of additional ground disturbance, and therefore the likelihood of disturbing archaeological remains. 5.9 In the event of significant remains being identified, EGAT would aim to minimise damage and, if appropriate, seek alternative tower locations. Otherwise, arrangements would be made for a suitable level of site recording of archaeological remains prior to and/or during construction works. CONCLUSIONS 5.10 The potential impacts from the Project consist of the loss of or damage to sites of archaeological importance and the adverse impact on the setting of cultural sites. 5.11 It is anticipated that the small increase in the size of the towers would not materially affect the setting of sites. Therefore, no known sites of cultural or historical interest would be affected more adversely than they already are by the existing 230 kV transmission lines. 5.12 There are no known archaeological sites along the existing Rights-of-Way, and it is unlikely that any will be found. If significant remains were found, damage to the site would be limited as far as was practicable and a suitable level of site recording would be arranged prior to and/or during construction works. 23 NONTh1A RniPj GRAPHIC SCALE J ~~~~~~~~~~~~~~ - ~~~~~~~~~~~~NABONIAL HIGH-WAYS C / - / 9- ~~~~~~~~~~~~~~~~~PROVINCIAL HIGHWAYS C N. ~~~~~~~~~~RAILWAYS if - / ~~~~~~~~~~~~~~~~~~~~~~~RIVER CANAL 'I flAj~~~~~~~~~~~ 1 i /~ ArPE A (to KRAS ly~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~U I BAGKO BIl ,FROMM( -KZ(. Kblo~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~,L IfOfl ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ c CHAPTER 6 LAND USE INTRODUCTI ON 6.1 A field survey of land uses was conducted along the existing four sections of 230 kV transmission line by TEAM during the last week of February, 1996. 6.2 The construction of the proposed 500 kV lines would temporarily affect some land uses along the route. In the longer term, the physical presence of the proposed towers and conductors would affect farming operations to some extent. There may also be an occasional need for access to land to inspect, maintain, adjust, alter, replace or repair the transmission lines. ASSESSMENT 6.3 The land use results from the field survey along the existing 230 kV transmission lines are presented in Table 6.1. This information is also presented graphically in Figures 6.1 to 6.5. The main land use within the area is agriculture, in particular paddy fields (56%), b,utI also ru. and vegetabie cuitivation and poultry and fish farming. Other land uses include urban (ie housing), institutional land (eg schools and temples), and a small amount of industry. 16% of the land has been abandoned. Potential Impacts During Construction 6.4 Dismantling of the existing 230 kV lines and construction of the proposed 500 kV lines would cause temporary interference to agriculture on land used for access and/or materials storage. Potential Impacts During Operation 6.5 During operation of the line, only the area immediately beneath each tower would be removed from cultivation. In addition, the immediate tower surroundings would take on the characteristics of field margins, ie typically having slightly lower yields and a greater chance of weed problems. This impact has already occurred due to the presence of the existing 230 kV line and therefore it is expected that any further change to the land use patterns along the proposed routes will be minimal. 6.6 Additional, temporary disruption may also occur when access is required for maintenance or repair of the proposed 500 kV line. MITIGATION 6.7 During construction, because the Project consists of a linear development, it is unlikely that any one area would be compromised for more than one growing season. Landowners will be informed of work schedules in advance so that they can plan accordingly. Any damage to land (eg to temporary dikes in paddy fields and fish ponds) A,>5 will be reinstated by EGAT, or appropriate compensation agreed where this is not possible. 6.8 Disturbance to land will also be minimised because a signifcant percentage of the new towers would be located on the site of existing towers. Until the final tower spotting exercise, precise statistics are not available. However alonn Bangkok Noi - Sal Nol, between 14 and 23 towers out of a total of 68 will be located at existing positions (ie between 20 and 33%). Along Sai Noi - Rangsit, of a total of 59 towers, between 19 and 25% will be at existing locations. There are only 20 towers between Rangsit and Chaeng Watthana, and between 6 and 8 of these will be at existing positions. Finally, of the 40 double circuit towers between Nong Chok and On Nuch, between 14 and 16 (representing 35 to 41 %) will be located on existing sites. 6.9 During operation, routine maintenance would be arranged with the landowner to avoid times when the crop is sensitive and therefore minimise any disruption. When urgent maintenance or repair is needed, EGAT would seek to minimise any disruption caused by access and working. CONCLUSION 6.10 The main land use along the proposed routes is agricultural. Disturbance caused during dismantling the existing 230 kV line and constructing the proposed 500 kV line would be minimised by liaising with the local landowners and choosing appropriate working times. 6.11 Impacts due to the operation of the proposed 500 kV lines already exist along the chosen routes because of the presence of the existing 230 kV lines, and would be minimised by the re-use of existing tower sites where practicable. 2 Lb Table 6.1 Land Use Categories along the Proposed 500 kV Transmission Lines Land Use Categories: Coverage in hectares Transmission LinesI U2 U3 U5 Al A4.1 A5.1 A8 A9.1 Al A1 U2 M1 W A9.1 M1 A4.1 Bangkok Noi - Sai Noi 6.50 1.25 - 100.5 3.50 11.25 - 11.25 1.75 12.00 Sai Noi - Rangsit 8.75 12.50 0.75 88.75 0.50 2.25 - - 1.50 10.00 Rangsit - Chaeng Watthana - 2.00 - - - 2.00 - - - 34.00 Nong Chok - On Nuch 16.50 5.00 - 36.50 - - 3.00 3.00 3.00 15.50 - 7.75 2.75 % of Total Land Area _ 7.86 5.14 0.19 55.88 0.99 3.84 0.74 0.74 0.74 6.62 0.80 15.78 0.68 U2 Urban U3 Institutional Land U5 Industrial Land Al Paddy Field A4.1 Mixed Orchards A5.1 Vegetables A8 Poultry Farm and Fish Pond A9.1 Fish Pond Ml Idle Land W Water Body 027 5e SINGLE HOUSE INDUSTRIAL PLANT ROW HOUSE RONG RIAN (SCHOOL) HIGHRISE BUILDING 0 X ILARGE BUILDING 4AGRICIULTURAL AREA Figure 6.1 Definition of Landscape Elements K CJ kJ ~~~ ~ ~ ~~~~ri r t i+or. -~~~~~~~ - - | r40.000 E 645,000 E 650.000 E 655,000 ELj SWt \ ~ \-i /1,545,000 N q,4\ $ s , ~~~~BAN KHLONG CHEK (2)|o 2KU " \.At > WAT AND RONG FIAN WAT SAI NOI | GRAPHIC SCALE BAN KHLDNG TA SANG (I)< .tJ X *- * t X \ /- HIGHWAY ROAD Sol , r| V 4t/J/ 0 U L \ 7i4e;vH~~~~~~AKORN KARNBIN lHA] 2/ / _ \ n h 4 R~~~~~~~~~~~~~~UNGARUN MLLAGE 7/9 \ X \ ~~~~~~CHATRADA VILLAGE e ? %% ~~~~g = ~~~CHOKPRACHA VILLA1 |/ R/ / POOPU MLA 3 X/s ' 1,535,00Lt N \ PRACHANUPPRILAlHUSH // ,, \ PRACHAHIVES VILLAGE /| CHEUJNKAMOL NIVAS I 1 \WT BUA KHWAN let/ // @ ' @ ~~~~~~~~CHEUNKAML)L NIVAS 2 //w - \TH~~~~~ANAKARN SONGKAO UAE|g RATANA THU8 E T It, /- // R _ ~~~~~~~~~KA TPRAPH A -- ----------- - / s I X * /A/ /~~I X -1,530,000 N |// Figure 6.4: Landscape Along Rangsit - Chaeng Watthana Route r - r r r - T I r , 1 1 LT r X T r - r r- I~~~~~~~~~~~~~~~~~~T 6800000 E 5.OE69000 E 695.000 E 700.000 E BAN LAW MOK < 'WE 0 1 2 KM. GRAPHIC SCALE 1.523.00) N LEGEND is// / ,.'BW 26> v 8AN K ONG SAM N..15 Hi/.' . HIGHWAY ROAD so / A SO t-I- -i RAILWAY 2 9 />J > z ~~~~~~~~~~~~~~KHWANG LAM PLATIU /-*SNL OS SINGLE HOUSE 2 tAT 7 RATC&I^CIX/ ' . _ / S ROW HOUSE BAN,'KOLONO JP CNANC B°,,84 r RKHWANG KHLONG SONG N NU . HIGHRISE BUILDING -1 LARGE BUILDING 1,520,COP( NL / E KHLONC I 1 I A INDIUSTRIAL PLANT KHET BANG " ^ S 2 * i _ PONG RIAN (SCHOOL) Al TEMPLE RON0 RIANJ SURAO THAP CH-AE AGRICUJLTURAL AE .AT DA.-08 SAT.1101 BAN PAKl KHLONGBEON t / KHWAG LAI KRAANG 1.515.000 N ! ILI _ ILI I I I I 1- 1 _ ___Fig I - ILdcp ln I L N Chok ___ _ FIgure 6.5: Landscape Along Nong Chok - On Nuch B.- Ij c - iINDUSTRIAL PLANT . SINGLE HIOUSE RONG RIAN (SCHOOL) RO(W HOUISE HIGHRISE BUILDING A GRICULTURAL AREA LARGE BUILDING FIGURE 2 LANDSCAPE ALONG 500 KV TRANSMISSION LINE FIGURE 1 LANDSCAPE ALONG 500 KV TRANSMISSION IINE wo. rw C t . . v # .s. ._E~~~~~~ ~~~I I I I I I I I I I I - - 1 I 640,000 C 65.000 t I 55.000 E K~~~~~~~~~~~~~~~~~~ AMP0CA SAl NOI 1 545,000 7 I'5A ' CHtK l2) 0 1 2KU _ AND ROANG RIAN A11 SA, NO GRAPHIC SCALE , 6-N OAIKJN( 2) | - ! \j - AIRIN WlO,NG t. SANG (1) 4 '6 tlU HL0UC TA CHO 1\ \// HIGHWAY ROAD - sai _ i | 9 *|- \ | - -- ~~~~~~~~~~~~~~~~~~~~KHLONG \f I J _ || | RAILWAY - \ \ 9 , io 8A~~~~~~~ NONG KRADI11(2) ..\_ _ _ , 12 *| * 5 s . S INGLE HOUSE .Iurx wHLONs sl Ut* * * i 6ANX WN SA1NAf/ .. l j ROW HOUSE 0 HIGHRISE BUILDING \\ 6AN N 0"G PHLAO N CAU,(3)l ^| * i / \ t \ H535.000 U - a LARGE BUILDIIf 4*\ , | \ - d INDUSTRIAL PLANT RDNG RIAN (SCHOOL) \B\ _____ \_ | | X 6AN KHL GC IA UIUANC, \ 40t / X I _ TEMPLE \\ Lo A.0 I . LU ,1~ AGRIOLJLTU1IAL AREA \\,N T0IK CHU^ B,* AN ITALAT SANG KHV > ; n BAN BANC YAI (3)) : *\ ' /X\\ \ - BAR UA (1) Z \ \ ) BAN KHLONG SANG SANO . \ HAN KHLONC BANC KA HLO N \ IAH P0116 P101 6 lIlAt PAN K 6AN W1A "0KUN SRI -525,000 N L W^N TALIN~~~~C. C iJ BAN KLANC NA (2) /@,. (3\ BAN KHLONC AAN Pl - . - - A \ |} FAN KHLGUC 6ANG I X (TI s ~~~~~~~~1,520,000 N- \ r 8AN KHL 6ANCWAEK (1) BANR[7HAIT I) _ . . .... .. 1512000 FIGURE LANI)SCAPE ALONG 500 KV TRANSMISSION LINE -' L BANGKOK NOI SUBSTATION - SAI NOI SUBSTATION -NW ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~- RANG $RAD -v -- HIGH W AY .NOUSTRIAI. RHTA t [, 2 = KHONC aD ROW H0USE s RONG RlS XSCHCNN NNA .-)(310 . . U 4 w WAT SAPHAN *3N - NOIT SAB.ST O N- RUN A 0045~~~~~~~~~~~~~~~~N MAN SAF-NAN SANG WlA? CHINWARNANAI T*~p A lIAN Al, ) N.~~~~~~~~1,..0 N N ~~~~~~~~~~~~~~~~~LEGEND - HICHWAY ROAD '- SINGLE HOUSE d INDUJSTRIAL PLANT Sol ~~~~~~~ROW HOUJSE RONG RIAN (SCHOOL) KHLONG 210' -H4+± ~~~~~~~ ~ ~ ~~~~~RAILWAY 0 HIGHRISE DUJILDING T EM-PLE GRAPHIC SCALE ~~~~~~~~~~~~~~~~~~~~~~~C LARGE BUILDING AGRICUTURAL AREA FIGURE LANDSCAPE ALONG 500 KV TRANSMISSION LINE .4.-3 SAI NOI SUBSTATION - RANG SIT SUBSTATION -/ /,,."<0 . 0 1 2Km. (( ( / i *\ GRAPHIC SCALE I.Al NA\ NG \LEG \ , )- -- | HIGHWAY ROAO -- KHLOIIG , -/ --i-f- RAILWAY :' / -SINGtE HOUSE rm ROW HOUSE .j | X / * <; - //< 0 HIGHRISE BUILDINC - 1.5.0.000 N el X | r TtPPRAtARN W L L //5/ O LARGE BUIA TEPPRATARND ALLA INDUSTRIAL PL 0 1 0 4 ~~~~~~~~~~~~~~~~~~RONG RIAN (SCo-I - Wt AUA4G Tl4 }0 6 A' WAT tRUWAtAtHAR @ _KHLONG -I/-H-+--t |RAILWAY - - ~~~~~~~~~~~~~~~~KHWANG LAM I'LATlU - / r > S KHWANG LAU PLAnU / - e SINGLE HOUSE _ _ an ROW HOUSE RAl (HI.ONT IHAP CIIANO 8 / l KHWANG I'KHLONG SONG N NUt r HIGHRISE BUILOING -t.5200o2N ~/ .1.I I 'BAN MA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~LARGE BUILDING _.2000 / 1 8^N KHLONC U^1 CHAN \ ( y INOUSTRIAL PLANT RONG RIAN (SCHOOL) |r / It KHET LAT KRABANGIE EPLE RONG -RI+,|| p 4; + - AGRICULTUFAU L AREA /- A / lO§CJLAT KRA9iC / <_ > -| LA I I I I I I I ! I I I I I I I I~ ~ ~~ ~ I I I I I I FIGUPE V' LANDSCAPE ALONG 500 KV TRANSMISSION LINE NONG CHOCK SUBSTATION - ON NUCH SUBSTATION CHAPTER 7 WATER QUALITY INTRODUCTION 7.1 Due to the location of the Greater Bangkok Area in the central plain of the Chao Phraya river, many of the khlongs and waterways were crossed during the 230 kV transmission line development. A list of affected water courses is presented in Table 7.1. These waterways will potentially be the receptors of any aquatic pollution generated by the 500 kV transmission line development. 7.2 Although the proposed 500 kV development will be limited to the existing Rights-of-Way, -- the construction activities will still involve soil disturbance and the use of heavy machinery. Therefore, there may be some impact on the local water quality in the form of additional suspended solids and spills of oil or grease during the construction period. ASSESSMENT 7.3 Data has been collected on the existing water quality data as the baseline for future impact assessment. A sampling program was undertaken by TEAM on 8 and 9 February, 1996. to examine the existing w'ater quality along t Ri,gh+-of-Way. 'Te sampiing stations were as follows: i Station 1: Khlong Prapa, near Ngam Wong Wan Intersection Khlong Prapa at the sampling point was about 20 m wide, with quite turbid water of a brownish colour. The flow was relatively low. No floating weeds or garbage was observed in Khlong Prapa. This station was located about 20 m from the edge of the existing 230 kV transmission line Right-of-Way. * Station 2: Chao Phraya River at Wat Kroen, Tambon Bang Kra Dee, Amphoe Muang, Changwat Phrathum Thani This station was located at the pier in front of Wat Kroen, about 15 m from the river bank. This area suffered in the flood of November 1995. The water was ) relatively clear with normal flow. Water hyacinth were present along the river bank. Upstream and downstream from the sampling station, there were 5-10 sand barges docking along the bank. In addition, a tapioca factory was located next to the wat and a log terminal was approximately 100 m away. This sampling point was about 50 m from the 230 kV transmission line Right-of-Way. * Station 3: Khlong Phra Pimon at Wat Sai Noi, Tambon Sai Noi, Amphoe Sai Noi, Changwat Nonthaburi This station was in front of Wat Sai Noi. The khlong was densely covered with water hyacinth, although an H2S odour was perceptible from the khlong where the water was blackish. Small communities were observed on the bank opposite Wat Sai Noi. This station was about 50 m from the existing transmission line Right-of- Way. 7.4 Analysis of the samples revealed that the quality of the waterways during the dry season (February, 1996) was relatively consistent (Table 7.2). The water temperature ranged from 25 to 270C and the pH from 8.0 to 8.7. The conductivity was found to be relatively low in Khlong Prapa (230 pmho/cm) and up to 320 pmho/cm in Khlong Phra Phimon (due 1'33 to the high levels of H2S dissolved in the water). This high conductivity also correlated vith a relatively high total solids of 412 mg/l and a relatively low dissolved oxygen (DO) of 3.9 mg/l in Khlong Phra Phimon. 7.5 Overall, the water in Khlong Prapa and the Chao Phraya was soft (alkalinity of 88-92 mg/I) with relatively high DO (ahout 6 mng/). 0! and nrease contamination was detected at the relatively high concentration of about 2.0 mg/l. From the above analyses, the three waterways, ie Khlong Prapa, the Chao Phraya river (at Wat Dao Wadung) and Khlong Phra Phimon, can be classified as rank 3, 3 and 4 according to the Ministry of Science, Technology and Environment (MOSTE) standard (Reference 7.1). Definitions of these water quality classes are given in Tables 7.3 and 7.4. Potential Impacts 7.6 As operation of a high voltage transmission line does not involve any emissions, the only potential long-term impact on water resources consists of alteration to drainage patterns due to the interruption of existing drainage. -;) 7.7 The major potential impacts on water quality arise from construction activities and are as follows: * surface run-off from the construction sites. * wastewater from the temporary office and construction camps. * wastewater contaminated with oil or grease from machinery. 7.8 Surface run-off from construction sites will have increased suspended solids due to the soil disturbance associated with tower foundation construction. The potential impact will be minimised because only the relatively small area around the tower base will be affected. Therefore, the potential impact due to increased suspended solids in surface run-off is not expected to be significant. 7.9 Dismantling the existing 230 kV transmission lines will involve minimal soil disturbance because, in general, the towers will be removed to ground level and the concrete foundations left in place. 7.10 Temporary offices and construction camps will be equipped with sanitary latrines which will take care of all domestic waste prior to discharge into nearby waterways. Thus the potential negative impact of wastewater disposal is negligible. 7.11 The 500 kV transmission line development will utilize a large amount of heavy machinery and construction equipment. Routine maintenance of this equipment will be restricted to within designated maintenance areas or garages. In these facilities, waste oil will be contained in designated containers and properly disposed of. Therefore, any potential impact due to oily contamination should not occur. 7.12 There will be no adverse effects on water quality due to the operation of the proposed 500 kV transmission lines. ,Z3L4 MiTIGATION 7.13 The Rights-of-Way for the 500 kV transmission lines already exist because of the 230 kV development. Therefore, only minimal additional clearing will be necessary. 7.14 Detailed tower locations would be agreed with reference to protection of existing drainage and dikes. Crossing of ditches and drains (where necessary) would be carried out by the construction of temporary bridges, able to bear the weight of plant and loads without damage to the integrity of the watercourse. Where any field drains or dike systems are disturbed during construction, these would be reinstated. 7.15 Surface run-off from construction sites will mainly be a problem in the rainy season. The major construction activities will therefore be scheduled for the dry season (November - April). In addition, the area disturbed during tower construction will be kept to a minimum. 7.16 Good housekeeping procedures will minimize any potential water contamination due to - oily waste and chemicals. Adequate sanitary latrines will be constructed at all temporary -_) offices and construction camps. -, CONCLUSIONS 7.17 The fact that the proposed 500 kV transmission lines are to be built in existing Rights-of- Way means that the impact on water quality in the area is expected to be small. This smnal impact w,ll be further, estricted by working in the d,y season (when practicable) and by proper control of wastewater from the construction sites. 7.18 There will be no impact on water quality during the operational phase of the 500 kV transmission line project. This is because there are no emissions caused by the operation of a high voltage transmission line, and because care will be taken not to interfere with existing drainage patterns. 35 Table 7.1: Waterways Potehtially Affected by the 500 kV Transmission Line Development Route Waterway Name Class Bangkok Noi - Sai Noi Kh!onr' Phra Phinom 4 Khlong Ta Chom Khlong Nai Lik Khlong Som Nuk Khlong Bang Yai Khlong Mahasawat Khlong Bang Noi Khlong Bang Chuk Nang Khlong Bang Phai Khlong Bang Weak . - Khlong Bang Khi Kaeng Khlong Bang Chak Sai Noi - Rangsit Khlong Lam Ri Khlong Lak Khon Khlong Lam Pho Khlong Lam Yai Khlong Bang Tanai Khlong Ko Kriang Khlong Bang Khu Wat Tai Khlong Bang Khu Wat Nua Chao Phraya River 3 Rangsit - Chaeng Watthana Khlong Rangsit Prayoonsak 3 Khlong Ban Mai Khlong Bang Talad Khlong Bang Khem 5 Nong Chok- On Nuch Khlong Mae Chan Khlong Lam Bung Khwang Khlong Al So Khlong Song Ton Nun Khlong Sam Khlong Si Khlong Lam Phaeng Phouy Khlong Bung Yai Khlong Lam Nok Khwaek Khlonq Lad U-Ta-Phao 4t36 Table 7.2: Results of TEAM Surface Water Quality Survey (9 February 1996) l___ .____ Water Quality Z Parameters Khlong Prapa Chao Phraya river Khlong Phra Phimon air temperature in °C 26 25 29 water temperature in DC 25 *25 27 depth in metres 2.5 2.0 2.7 transparency in metres 0.5 0.5 0.5 pH 8.7 8.2 8.0 Conductivity in pmho 230 250 320 turbidity in NTU 58.0 45.0 29.0 alkalinity in mg/I 88.0 92.0 112.0 total solids in mg/I 360.0 372.0 412.0 suspended solids in mg/l 67.5 47.0 38.0 hardness in mg/l 111 107 129 DO in mg/l 6.0 5.9 3.9 oil & grease in mg/l 2.2 2.0 2.2 NO3 - N in mg/l 0.62 0.71 0.53 cloud cover in % 0 0 0 time of sampling 1000 1130 1400 Class e Table 7.4) 3 3 i~~~~~~~~~~~~~"1 Table 7.3: MOSTE Surface Water Quality Classification (Reference 7.1) [arameters U n Standard Values for Class (see Table 7.4) Parameters Units j StatistiC 1 2 3 | 4 | 5 temperature n' n' n n' pH n 5 9 5 9 5-9 DO mg/l P20 n 6 4 2 - BOD (5 days, mg/I P80 n 1.5 2.0 4.0 - 20 °0) coliform bacteria - total MPN/100 ml P80 n 5,000 20,000 - fecal MPN/100 ml P80 n 1,000 4,000 NO3 - N mg/i max n 5.0 5.0 5.0 NH3- N mg/l max n 0.5 0.5 0.5 phenols mg/i max n 0.005 0.005 0.005 Cu mg/I max n 0.1 0.1 0.1 Ni mg/l max n 0.1 0.1 0.1 Mn mg/I max n 1.0 1.0 1.0 - Zn mg/! max n 1.0 1.0 1.0 - Cd mg/l max n 0.005* 0.05** 0.05** Cr (hexavalent) mg/i max n 0.05 0.05 0.05 Pb mg/I max n 0.05 0.05 0.05 - Hg (total) mg/l max n 0.002 0.002 0.002 - As mg/l max n 0.01 0.01 0.01 CN mg/I max n 0.005 0.005 0.005 Radioactivity - gross Bq/l max n 0.1 0.1 0.1 - gross Bq/l max n 1.0 1.0 1.0 Pesticides - DDT mg/i max n 0.05 0.05 0.05 - BHC mg/l max n 1.0 1.0 1.0 - Dielrin mg/l max n 0.02 0.02 0.02 - Aldrin mg/i max n 0.1 0.1 0.1 - Heptachlor & Heptachlor mg/I max n 0.1 0.1 0.1 epoxide - Endrin mg/l max n none none none no value n' expected ambient temperature, but changing by less than 30C n expected naturally occurring concentration P percentile value * 0.05 mg/l when water hardness not more than 100 mg/l CaCO3 0.05 mgA when water hardness more than 100 mg/l CaCO3 Table 7.4: MOSTE Surface Water Quality Classification (Reference 7.1) Classifications Condition and Beneficial Usages Class 1 Extra clean, fresh surface water resources, suitable for: (1) conservation (water treatment not required, only ordinary processes for destruction of pathogens) (2) ecosystem conservation (where basic living organisms can proliferate and breed naturally) Class 2 Very clean, fresh surface water resources, suitable for: | . (1) consumption (but requiring ordinary water treatment before use) (2) aquatic organism conservation (may be in support of fisheries) (3) fisheries (4) recreation Class 3 Medium clean, fresh surface water resources, suitable for: (1) consumption (following ordinary water treatment before use) (2) agriculture Class 4 Fairly clean, fresh surface water resources, suitable for: (1) consumption (but requiring special water treatment before use) (2) industry (3) other activities Class 5 The resources which are not covered by Classes 1 to 4, suitable for: (1) navigation ,J~~~~~~~~~~~~~~~~re CHAPTER 8 FLORA AND FAUNA INTRODUCTION 8.1 Potential impacts to the ecology of an area from the construction and operation of a new transmission line normally include loss of habitats (mainly at tower bases), loss of species due to habitat loss, fragmentation of habitats, severance of ecological corridors and disturbance to bird feeding or roosting activities. 8.2 The four sections of proposed 500 kV transmission line pass through the Bangkok -. Metropolitan Area, which has already been developed into a combination of residential, N industrial and agricultural land. Therefore, there is little wild flora or fauna remaining in the Rights-of-Way. In addition, the presence of the existing 230 kV transmission lines mean that any ecological impacts mainly already exist. 8.3 The assessment of flora and fauna has therefore been divided into two parts; potential impacts on the aquatic ecosystem due to an increase in suspended solids in adjacent waterways (mainly of concern should construction activities take place during the rainy season = sec Chapter 7) and other considerations assocaited with bird fiight paths. ASSESSMENT Aqati Ecology 8.4 Three waterways were selected as representative of the waterways potentially affected by the proposed development. These were Khlong Prapa, Chao Phraya river and Khlong Phra Phimon. The sampling stations used by TEAM for their initial study were the same as those used for the water quality study (Chapter 7). 8.5 All three watercourses were found to be dominated by phytoplankton (Table 8.1). However the dominant genus was different in each case. Coscinodiscus gigas was the dominant genus for Khlong Prapa, while Oscillatoria sp. and Microspora sp. were the dominant genera for Chao Phraya river and Khlong Phra Phimon respectively. The overall cell densities for Khlong Phra P,imon, Chao Phraya river and Khlong Prapa were 3.4 x 1 06, 2.0 x 1 05 and 1.8 x 1 05 cellsiM3 respectively. 8.6 Using the planktonic indicator species for water quality (Table 8.3), Ceratium sp. (an indicative species for moderate levels of pollution) was identified only in Khlong Prapa. - Oscillatoria sp., Fragilaria sp., and Spiruline sp. were found in high densities in the Chao Phraya river and Khlong Phra Phimon; these indicate a relatively high pollution load. 8.7 No benthic species were collected from Khlong Prapa due to the strong flow and drifting of the sediment (Table 8.4). The density and diversity of benthos were also low at Chao Phraya river and Khlong Phra Phimon. Only three genus were collected; Tubificid worm was the dominant group. The tubifex worm is associated with high pollution loads because it can survive in very poor environmental conditions, ie low DO, high Biological Oxygen Demand (BOD) and high H2S levels (Table 8.5). 8.8 Therefore, this initial survey indicates that the three sampling locations are not ideal aquatic ecosystems; this corresponds with the analyses of water quality contained in Chapter 7. Bearing in mind that the new 500 kV development will be located within the existing 230 kV Rights-of-Way, and thus only minimal additional land clearing will be required, and the fact that the waterways around the project area are already in a relatively poor condition ecologically, the impact on aquatic ecosystems will be relatively rninor. Bird Flight pathsa 8.9 There is extensive data on which bird species are most at risk from injury or fatal collision with transmission lines. Generally, the birds most likely to be at risk are large species with poor flight manoeuvrability (and occasionally poor visual acuity) or birds with high flight speeds (such as birds of prey). 8.10 Significant flocks of birds usually fly along the shoreline or mountain ridges. The study - - area is concentrated on the plains of the Chao Phraya river, and therefore major bird movements would not be expected in this area. TEAM's wildlife expert indicated that the only known migratory bird in this region is the Barn Swallow (Hirundo rustica) which flies each winter from its Siberian breeding grounds to the central business district of Bangkok (Silom). They arrive from the north, and therefore the proposed 500 kV transmission lines would not obstruct their passage. 8.11 There are no records of birds being injured by collision with existing EGAT transmission lines (including the existing 230 kV lines) in Thailand. MITIGATION 8.12 As already stated, there are no sites of significant ecological interest in the vicinity of the proposed 500 kV transmission lines. However, general guidelines would be followed to preserve the existing wildlife potential. Damage to trees, dyke systems and grassland would be avoided where possible. Where the lines would pass over or close to trees which could infringe safety clearances to live conductors, the trees would only be removed if absolutely necessary; preferably, they would be 'lopped" prior to the construction of the lines. Aquatic Ecog y 8.13 The mitigative measures already described in Chapter 7 (to maintain the quality of waterways in the study area) will also minimise distUrbance to the aquatic ecosystems. These measures included minimizing the disturbed area during construction, concentrating the major construction activities during dry season (November - April), minimizing any potential contamination due to the oily waste and chemicals by good housekeeping and constructing sanitary latrines at all temporary offices and construction camps. Bird Flight paths 8.14 Although there is no evidence to suggest that the proposed 500 kV transmission lines would present a risk to birds, if a problem with bird fatalities were to arise, the possibility of placing "deflectors" or 'markers" on the shieldwire to make the line more visible to birds would be examined. A-i CONCLUSIONS 8.15 The existing 230 kV lines are in an area which has already been developed for a mixture of residential, industrial and agricultural uses. Therefore, there is little wild flora or fauna left in the study area. 8.16 TEAM's aquatic ecology survey indicated that the ecosystems present in the waterways which could potentially be affected by construction work are already poor. If the mitigative measures proposed in Chapter 7 (to maintain water quality) are applied, the potential disturbance to aquatic life is minimal. No impact is expected on aquatic ecology during the operational phase. 8.17 There is no evidence of an existing risk to birds caused by the operation of EGAT's existing transmission lines. There is therefore no reason to suppose that there will be a significant risk to birds posed by the proposed 500 kV lines. iL.2 Table 8.1: Species and AbUndances of Phytoplankton Abundances in cells/m3 Phylum Scientific Names Chao Phraya Khlong Phra Khlonn Prapa river mon Bacillariophyta (diatom) Coscinodiscus gigas 85,100 15,200 17,100 C. nitidus 2,300 Diatoma elongatum 6,900 7,600 133,000 Synedra tabulata 2,300 2,533 60,800 S. affinis 2,300 2,533 - S. ulna - 11,400 Ethmodiscus gazellae 2,300 - Melosira sp. 2,300 - 5,700 Surfrella robusta - 1,900 Bacillaria sp. 7,600 Pleurosigma sp. 5,700 Fragilaria construens 1,900 Gyrosigma sp. - 3,800 Cyanophyta (blue green algae) Oscillatoria sp. 4,600 38,000 1,164,700 Dictyosphacrium pul/chellumr 2,533 - Rivularia sp. 2,533 7,600 Spirulina major - 7,600 Lyngbya contorta - 3,800 Trichodesmium lacustre 1,900 Tribonema sp. 1,900 Chlorophyta (green algae) Spirogyra ionia 4,600 . 7,600 Pediastrum simplex 2,300 5,700 P. biradiatom - 22,800 Derbesia sp. - 10,133 11,400 Basicladia chelonum 2,533 - Microspora sp. - 25,333 1,369,900 Closterium gracilo - 100,700 Cl. cornu - 24,700 Cl. ehrenbergii - 1,900 Cl. moniliforme - 1,900 Euglenophyta (Euglenoids) Eugelna acus 39,100 - - E. granulata 6,900 - - Phacus pleuronectes - 1,900 P. longicauds ' 1,900 Pyrrophyta (dinoflagellates) Ceratium furca 4,600 - - Unidentified 1 2.533 5,700 |TotalI 165,600 _ 111,464 | 2,992,500 _ 4-3 Table 8.1: Species and Abundances of Zooplankton Abundances in cells/mr3 Phylum / Scientific Names Chao Phraya Khlong Phra Khlong Prapa river Phimon Arthropoda Nauplius (unidentified) 4,600 12,667 100,700 Copepod (unidentified) 2,300 2,533 7,600 Moina sp. - 1,900 Bosmina sp. - 1,900 Protozoa Centroptxis aculcata 2,300 11,400 Cyttarocystis cassis 2,300 - Tintinnopsis sp. - 2,533 - Loucophrys patula - 2,533 - Chilodonella sp. - 2,533 Loxodes magnus - 2,533 - Difflugia sp. - 1,900 D. acuminata . 9,500 Astramocba radiosa 9,500 Gaxeletta hexamcma 5,700 Euglypha tuberculata 1,900 Arcel'a polypoia 1,900 Rotifera Keratella valgn - 10,133 117,800 K. cochleariss - 17,733 49,400 K. scrulata - 12,667 47,500 Filini'a terminata - 2,533 9,500 F. brachiata - 2,533 - F. opoliensis - 1,900 Ploesoma triacanthum - 2,533 Brachionus pala - 2,533 - Br. plicatilis - 9,500 Br. faScatus - 11,400 Polyarthra sp. - 1,900 Pompholyx salcata - 9,500 Testudinella sp. - 11,400 Albertia typhylina - 5,700 Hexamema mira - 3,800 Annelida Maupasia sp. - 2,533 Mollusca Bivalve larva - 5,067 Unidentified 5,067 - Total 11,500 88,664 433,200 4 4 Table 8.3: Planktonic Organisms as Indicators of Water Quality (References 8.1 and 8.2) Water Quality Organisms High Pollution Load Medium Pollution Load Low Pollution Load SLaurIUesrrlus sp. Staurastrum sp. / Cyclotella sp. . Dinobryon sp. V Mallomonas sp. Oocystis sp. ._ _ Peridinium sp. / Ceratium sp. V Tabellaria sp. / Anabaena sp. / Aphonizomenon sp. / Microcystis sp. Melosira sp. / Fragilaria sp. Synedra sp. Oscillatoria sp. Spirulina sp. _/ _ Table 8.4 Species and Abundances of Benthic Organisms Abuncdances in indivduaIs/m2 Organisms . Chao Phraya Khlong Phra Khlong Prapa river Phimon Phylum Annelida Class Oligochaeta (Earthworm) Family Naidiae 88 Family Tubificidae 220 396 Phylum Mollusca Class Gastropoda Order Mesogastropoda Family Ampullariidae Pila sp. 88 - Order Neogastropoda Family Marginellidae Rivomarginella sp. 88 Total 308 572 45 Table 8.5: Benthic Organisms as Indicators of Water Quality Water Quality Organisms High Pollution Medium Pollution Low Pollution Load Load Load Ephemerella sp. (mayfly) _ Nais sp. (worm) / Asellus sp. (bug) / Sialis sp. (alderfly) / Chironomussp. (midge) / Tubifex sp. (worm) / Limnodrilus sp. (worm) / CHAPTER 9 ELECTRIC AND MAGNETIC FIELDS INTRODUCTION 9.1 This section considers the environmental consequences of the electric and magnetic fields produced near transmission lines. The effects include possible effects on health, perceptible -effects of high electric fields, such as "microshocks", and effects on implanted heart pacemakers. The effect of power-frequency magnetic fields on certain electronic equipment such as cathode-ray-tube-based visual display units (VDUs) is covered in Chapter 1 1. 9.2 The relevant data on possible health effects have been reviewed by a number of national and international authorities and their conclusions are also presented. ASSESSMENT Field Magnitudes 9.3 The electric field produced by a transmission line depends on the voltage of the line, which remains essentially constant. The magnetic field depends on the current carried by the line, which varies according to the demand for power at any given time. 9.4 The field strengths at ground level near transmission lines are greatest directly below the conductors and fall as the distance from the line increases. The precise field strengths at any given point depend on a number of additional factors, including the spatial configuration of the conductor array and the arrangement of the three electrical phases. For all the following calculations, it has been assumed that the phasing on the double circuit lines is transposed, ie the phase order on one side of the tower is the reverse of that on the other. The situation for the quad circuit section is slightly more complicated, and has therefore been illustrated in Figure 9.1. 9.5 EGAT's technical specification states that the electric field strength should not exceed 15 kW/m within the Right-of-Way or 2 kV/m at the edge of the Right-of-Way. Magnetic field strengths with load currents of 4 kA per circuit should not exceed 15 pT at the edge of the Right-of-Way. Electric Fields 9..6 The electric field near ground level beneath a transmission line is strongest where the conductors are closest to the ground, normally at mid-span. The ground-level field strength diminishes towards the towers, partly because the clearance is normally greater there and partly because the towers have a screening effect. The field strength also generally diminishes with lateral distance from the line. 9.7 Objects on the ground such as fences, trees or buildings have a screening effect similar to that of the towers and ground-level field strengths in their neighbourhood are reduced. Most buildings efficiently screen their interiors against external sources of electric fields. 147 9.8 Calculated rms (root-mean square) electric field strengths in kilovolts per metre (kV/m) at one metre above ground level are shown in the Table 9.1. The calculations assume that the conductors are horizontal at clearances of 13 and 16 metres above ground level, and that the ground is also flat and horizontal. 9.9 In practice, the field strengths are unlikely to reach the maximum values quoted because conductor clearances would n-iormaily be greater than 13 metres (the standard clearance will be 16 metres at mid-span) and because of the screening effect of buildings, vegetation and other objects on the ground. Magnetic Fields 9.10 The ground-level magnetic field of a transmission line is strongest where the conductors are closest to the ground and its strength diminishes with lateral distance from the line route. However, unlike the electric field, the magnetic field is not much screened by the towers, vegetation or buildings. 9.11 -Calculated rms (root mean square) magnetic field strengths in microtesla (pT) at one metre above ground for the proposed line designs are shown in Table 9.2. The calculations assume that the conductors are horizontal at clearances of 13 and 16 metres above ground level and that the ground is also flat and horizontal. Loads currents are assumed to be 4 kA per circuit. 9.12 The field strengths would rarely attain these extreme values, because conductor clearances are normally greater than the design minimum and because load currents are normally less than the 4 kA assumed in the above calculations. Effects on People Electric Fields 9.13 A person standing in an electric field of about 10 kW/m would have an alternating current induced in his or her body which could reach approximately 150 pA, about a thousand times less than is needed to power a small flashlight bulb and too small to be directly perceptible (most people cannot perceive currents less than 500 pA). However, the electric field itself could cause perceptible hair vibration (on the back of an upraised hand, for example). 9.14 In certain circumstances, small spark discharges could pass as the person touched other objects, producing a prickling sensation similar to that caused by the static discharges commonly experienced in dry atmospheric conditions after frictional contact with a nylon carpet or car seat. Normally, any sensation is confined to the momentary spark discharge as contact is made or broken. However, a steady contact with a large structure in poor electrical contact with the ground, such as a lorry or other large vehicle, may allow a perceptible current to pass through the body to ground. This is unlikely to occur unless the vehicle has tyres which provide unusually good electrical insulation and it is standing on dry ground. A simple earthing connection between the object and the ground is normally an effective solution to the problem. 9.15 In the early 1 970s, reports from the Soviet Union claimed that workers in new 500 kV and 750 kV substations suffered a number of non-specific health symptoms, which were ascribed to exposure to hiigh electric fields. However, research in the USA, Canada, France, Spain, Sweden and in this counlry on a variety of individuals, including overhead linesmen, substation workers and members of the public living close to overhead lines, Z1+89 has failed to substantiate any association between exposure to power-system electric fields and adverse effects on human health. 9.16 A World Health Organisation report (Reference 9.1), concludes: "Whilst it would be prudent in the present state of scientific knowledge not to make unqualified statements about the safety of intermittent exposure to electric fields, there is no need to limit access to regions where the field strength is below about 10 kV/m." Magnetic Fields 9.17 The ground-level magnetic field of a transmission line will normally induce a much smaller current in a person's body than the current induced by the electric field of the line. In a magnetic field of strength 10 pT, the total induced current could reach approximately 3 pA. Unlike the electric field, the magnetic field has no directly perceptible effects on the body. 9.18 In some circumstances, however, the magnetic field may induce perceptibly large voltages and currents in long metallic objects (such as pipelines or telephone cables) -) parallel to the transmission line. This issue is covered in more detail in Chapter 11. 9.19 Recent epidemiological studies, particularly in the United States and in Scandinavia, have suggested an association between the incidence of childhood cancer and the proximity of homes to power transmission and distribution wires. Power-frequency magnetic fields have been postulated as a possible reason for the association. However, no causal link between cancer and magnetic (or electric) fields has been shown and indeed there is no known way that these fields cou-lu cause o, promote the disease. 9.20 The question of possible health effects of weak power-frequency fields has been thoroughly reviewed in recent years by bodies such as the World Health Organisation, the International Radiation Protection Association, the UK National Radiological Protection Board and the US National Academy of Sciences (References 9.1 to 9.5). None of them has concluded that these fields are a health hazard, although all agree that more research is necessary to answer some of the questions that have been raised. bther Effects Cardiac Pacemakers 9.21 Power-frequency electric and magnetic fields due to transmission power lines constitute a possible source of interference with the operation of some types of implanted cardiac pacemakers. Most pacemakers are designed to 'fail safe' by reverting to fixed-rate operation when they sense the presence of interference above a certain level. The field strengths necessary to induce such behaviour vary from one pacemaker model to another and may, in some circumstances, be encountered in the vicinity of high-voltage transmission lines. 9.22 The likelihood of patients encountering high-voltage transmission line fields large enough to affect their pacemaker is small, and there has been no recorded case in Britain of a patient coming to any harm in this way. The UK Department of Health, Medical Devices Directorate, does not consider that transmission line electric or magnetic fields constitute a significant hazard. 4 Livestock and Crops 9.23 Studies in the USA, Sweden and elsewhere have found little evidence that exposure of crops, farm animals and natural ecosystems to transmission line electric and magnetic fields has any agriculturally significant consequences. One positive finding concerns bee hives installed in the highest-field-strength areas beneath transmission lines. Voltages induced in the hive structure can cause the bees to experience electric shocks, which affect their behaviour and honey production. MITIGATION 9.24 EGAT agrees that even a remote possibility of a health risk must be taken seriously, because very large numbers of people are exposed to power-frequency fields from both overhead and underground power lines and from many other sources, including domestic electrical appliances. Further studies are in progress worldwide to establish whether or --not there is any real cause for concern. 9.25 The problem of the effects on bees caused by voltages induced in the hive structure can be solved by fitting an earthed screen of chickenwire over the hive. It is therefore concluded that eiectric and magnetic fields are unlikely to cause any problems with farming or related operations in the vicinity of the proposed transmission lines. CONCLUSIONS ' 9.26 Bearing in mind that the standard ground clearance would be 16 metres, the proposed 500 kV transmission lines will produce power-frequency electric fields at 1 metre above ground level under normal operating conditions of significantly less than maximum design value of 15 kV/m and less than 2 kV/m at the edge of the Right-of-Way. The short section of quad cirouit line may produce electric fields slightly in excess of 2 kV/m (2.16 kV/m) at the edge of the Right-of-Way under certain outage conditions. 9.27 These electric field strengths are less than those produced by EGAT's existing 500 kV line design which is already used in the Greater Bangkok Area. 9.28 The maximum power-frequency magnetic-field strength encountered at 1 metre above ground level will be less than 40 pT within the Right-of-Way and normally less than 15 pT at the edge of the Right-of-Way (remembering that the standard ground clearance would be 16 metres). The one possible exception is during a single circuit outage on the proposed double circuit line, when the level at the edge of the Right-of-Way may reach 17.3 pT. 9.29 These magnetic field strengths are less than those produced by EGATs existing 500 kV,' line design which is already used in the Greater Bangkok Area, and the maximum levels are comparable to those produced by the existing twin-conductored 230 kV lines which are to be replaced. 9.30 Environmental problems due to electric and magnetic fields are therefore likely to be limited to interference with the image on cathode-ray-tube based VDUs operated close to the Right-of-Way. This is discussed in Chapter 11. Table 9.1 : Predicted Electric Field Strengths Maximum Electric Field at Tower Desian Voltage Clearance Electric Edges of Right-of- in metres Field in Way in kV/m kV/m double circuit (DCT) both ccts at 13 5.31 1.86 1.86 500 kV 16 3.62 1.74 1.74 double circuit (DCT) one cct at 13 6.68 2.00 0.13 500 kV, one 16 4.83 1.97 0.25 cct earthed quad circuit (QOCT) four ccts at 13 5.57 2.08 2.08 5D0 kV 16 3.79 1.93 1.93 quad circuit (QOCT) one side at 13 6.68 2.23 0.15 500 kV, one 16 4.84 2.16 0.26 side earthed existing 230 kV line used both ccts at 7.5 4.20 0.15 0.15 in Greater Bangkok Area 230 kV existing 500 kV line used both ccts at 13 6.02 2.76 2.76 in Greater roaI n vkok Area __00 kV Table 9.2: Predicted Magnetic Field Strengths Maximum Magnetic Field at Tower Design Current Clearance Magnetic Edges of Right-of- in metres Field in Way in pT .__ _ _ _ _ _ pT double circuit (DCT) both ccts at 13 38.3 13.7 13.7 4 kA 16 25.7 11.1 11.1 double circuit (DCT) one cct at 4 13 35.6 20.8 11.7 kA, one cct 16 25.9 17.3 10.5 earthed quad circuit (QOCT) four ccts at 4 13 39.0 15.7 15.7 kA 16 26.5 12.4 12.4 quad circuit (QCT) one side at 4 13 30.6 18.5 9.3 kA, one side 16 21.4 14.6 8.0 earthed existing 230 kV line used both ccts at 7.5 40.0 5.2 5.2 in Greater Bangkok Area 2 kA existing 500 kV line used both ccts at 13 45.6 19.5 19.5 in Greater Bangkok Area 4 kA 51 Figure 9.1: Assumed Phasing for Proposed Quad Circuit 500 kV Line Design A C B B C A A B B A X ~~~~~C CHAPTER 10 AUDIBLE NOISE INTRODUCTION 10.1 An energised transmission line can be a source of a phenomenon known as "corona discharge" (a limited electrical breakdown of the air) which can also occur naturally during storms when highly charged clouds induce high electric fields around tall objects such as ships' masts or projections from buildings. Such corona discharge is sometimes seen at night and has been called "St. Elmo's Fire". 10.2 While power transmission line conductors are designed and constructed to minimise corona, surface irregularities caused by damage, insects, raindrops or other forms of - - contamination may locally enhance the electric field strength sufficiently for discharges to occur. Any corona discharge will act as a source of audible noise (a crackling sound occasionally accompanied by low frequency hum). 10.3 Methods for predicting the noise level generated by a new transmission line design have been developed, and hence the environmental acceptability of the proposed line design can be assessed. The results of this assessment therefore form part of the information used during the line design process. ASSESSMENT Qeneral 10.4 Transmission line noise is generated when the conductor surface electric stress exceeds the inception level for corona discharge activity. Transmission line conductors are designed to operate below this threshold. Surface contamination on a conductor will, however, cause a local enhancement of electric stress and possibly initiate discharge activity. At each discharge site, a limited electrical breakdown of the air occurs. A portion of the energy associated with the corona process is released as acoustic energy and radiates into the air as sound pressure waves. 10.5 Transmission line audible noise is generally categorised as "crackle" or "hum", according to its tonal content. 'Crackle" is a sound containing a random mixture of frequencies over a wide range, typically 1 to 10 kHz. No individual pure tone can be identified for any significant duration. 'Crackle' has a generally similar spectral content to the sound of rainfall. "Hum" is a sound consisting of a single pure tone. Generally 100 Hz is most significant, but other harmonics of the power frequency may occur to a lesser extent. 10.6 The highest noise levels generated by a line generally occur during rain. Water droplets collect on the surface of the conductor and may initiate corona discharges. The number of droplets, and hence the noise level, will depend primarily on the rate of rainfall. 10.7 Alternatively, after a prolonged spell of dry weather without rain to wash the conductors, contamination may accumulate sufficiently to result in increased noise. During the next heavy rain storm, the discharge sources are removed and the line reverts to being quiet. 10.8 It should be noted that when the line is first energised, noise levels in excess of those predicted below are possible. A decrease to the long-term noise levels will occur during an initial ageing-in period, the length of which depends on prevailing meteorological conditions and local levels of air pollution. However, this progressive ageing-in process should be well advanced after a period of 12 months. Foul WeatherAudible Noisp Prediction 10.9 A method developed by the Bonneville Power Administration (BPA) is used to predict the L,0 audible noise level in a foul weather at a given distance from the proposed line designs (Reference 10.1). This method uses the average maximum surface electric stress for each subconductor bundle as input data, along with the number of subconductors in each bundle, the diameter of the subconductors and the distance to the observer. The distance to the observer has been taken as the distance to the edge of the Right-of-Way, ie 20 metres. 10.10 The calculations have assumed a minimum ground clearance of 13 metres, although it will usually be 16 metres or greater. This is therefore a worst-case. The phasing assumed was as described in Chapter 9, ie fully-transposed, in order to minimise the ground level electric and magnetic fields. 10.11 Using the BPA method to calculate the Ls -in foui weather for the proposed double circuit line design with both circuits operating at 500 kV gives an answer of 43 dB(A). For the quad circuit line design with all circuits operating at 500 kV, the predicted L. in foul weather is also 43 dB(A). This is due to a combination of factors, including stress reduction on the bundles on the middle two cross-arms and the fact that the upper circuits are further from the ground, cancelling out the increase in noise due to a doubling of the number of potential noise sources. 10.12 When the quad circuit line is built initially, there will be just two 500 kV circuits on the top cross-arms. The bottom cross-arms will remain unstrung until there is a need for further capacity. The audible noise performance of this configuration has therefore been considered; the predicted L. in foul weather is 40 dB(A). Comparison with Existing Line Designs 10.13 The existing line between Bangkok Noi and Sai Nol (which is to be replaced by the double circuit 500 kV line) operates at 230 kV and uses a single ACSR 42/7 1272 MCM conductor per bundle. Using the above technique to predict the Lso in foul weather at the edge of the Right-of-Way gives an answer of 42 dB(A). 10.14 Other existing 230 kV lines in the Bangkok area (which are also to be replaced by the double circuit 500 kV line) use twin ACSR 42/7 1272 MCM conductors. These therefore have a better audible noise performance in foul weather; the L., predicted according to the same technique is 27 dB(A). 10.15 Because the decibel scale is logarithmic, a casual listener would not be able to distinguish between a noise at 42 dB(A) and the same noise at 43 dB(A). This means that the noise performance of the proposed line designs can be considered to be identical to that of the existing 230 kV line between Bangkok Noi and Sai Noi. Neither of these line designs have been the subject of complaints about audible noise. z5 Foul Weather Audible Noise Assessment 10.16 For audible noise, the Electricity Generating Authority of Thailand (EGAT) required that the LR, in foul weather should nct exceed 55 dB(A) at the edge of the Right-of-Way. Both the proposed line designs have a predicted L., in foul weather of 43 dB(A) when fully operational at 500 kV. This is well within the audible noise limit proposed by EGAT. 10.17 The proposed line designs have a predicted noise performance which is practically identical to that of the existing 230 kV line between Bangkok Noi and Sai Noi. This has not been the subject of complaints about audible noise, and therefore it is unlikely that the new line designs will provoke complaints about audible noise. MITIGATION 10.18 The proposed lines have been designed such that the predicted foul weather audible - noise levels are well within those required by EGAT and comparable to the noise levels generated by existing, acceptable line designs of a lower voltage. Therefore, no further mitigation is proposed. CONCLUSION 10.19 The predicted audible noise performance of the proposed line designs in foul weather is well within the level required by EGAT and comparable with that of existing, acceptable line designs of a lower voltage. Therefore, both the double circuit and the quad circuit line designs are environmentally acceptable from an audible noise point of view. /55 CHAPTER 11 ELECTRO-MAGNETIC COMPATIBILITY INTRODUCTION 11.1 Few complaints about electro-magnetic compatibility (EMC) arise from the normal operation of overhead lines. Those that do are often caused by unsuitable or faulty equipment or its installation. 11.2 There have been no reported incidents of interference from overhead lines affecting private radio transmissions or the emergency services. The main concems relate to TV interference (as raised during the socio-economic survey in Chapter 4) and a screen interference phenomenon known commonly as 'VDU wobble". - ASSESSMENT Corona Discharge 11.3 Whether wet or dry, corona discharge from high voltage equipment will affect television or radio reception will depend on the signal strength (S) of the required broadcast, and upon the strength of the corona interference 'noise' (N) at the same frequency and bandwidth. If a suitably high signal-to-noise (S/N) ratio can be maintained within the transmitter service area then no interference will be experienced. 11.4 A revised international standard for the limits of interference radiated by high voltage overhead lines is currently awaited (reissue of CISPR 18-3). The previous standard recommended a field strength limit on 1MHz Radio Frequency Interference (RFI) corona noise from overhead lines of 4.5 millivolts/metre at 20 metres from the nearest high voltage conductor. In practice, radio frequency corona levels will rarely approach this limit. Such a limit ensures that all amplitude-modulated (AM), long and medium wave (LW and MW) radio receivers further than 300 metres from the line would be free from overhead line interference even under the worst possible weather conditions. As the surface electric field of the new quad-conductored 500 kV transmission lines is very similar to that of the existing single-conductored 230 kV ones, similar corona RFI levels are also expected. Hence conformity to EGAT's technical specification of 40 dB at 20 metres is unlikely to be changed. 11.5 Corona interference predominates at the lower frequencies mostly used for long and medium wave (LW and MW) radio broadcasting and by some portable telephones and is of little or no consequence in the VHF radio band or the UHF television bands. The sound signals of public VHF and UHF broadcasting are less susceptible to interference than to those at long and medium waves because they use frequency modulation (FM) rather than amplitude modulation (AM). 11.6 UHF and satellite television reception and cellular telephones use frequencies well above those of any significant corona noise and should never be subject to any interference because of corona discharge from the proposed overhead line. For similar reasons, cable network services are also likely to be immune from interference. 5t Spark Discharge 11.7 Spark discharge can be a persistent or an intermittent phenomenon, and is normally associated with a faulty connection or other imperfection of the line equipment; such a condition could possibly affect television and radio reception and other equipment in the vicinity. However, any effects should only be short-term because high voltage overhead lines are built and maintained to high standards and any such sparking wouid be the subject of remedial action. Rflection' 11.8 As with light, broadcast and communication signals (especially VHF/UHF ones) can be reflected, and any conducting object, be it chimney stack, industrial plant, building, tree or overhead line tower can to some degree cause such reflections. Such effects are sometimes noticeable on television pictures as a ghost double image on the screen, only if the received signal arrives both directly from the transmitter and of sufficient strength -via a reflected path. This reflection phenomenon can also affect microwave communication links, and the normal remedy in such cases is simply to re-orientate the receiving aerial in order to make best use of its directional properties. In fact, experience has shown that the likelihood of overhead line interference with such services is negligible, although it is recommended that any new microwave iinks are positioned so as to avoid a path directly through a transmission tower or line. Shielding 11.9 Shielding of VHF/UHF radio and television reception due to the presence of overhead line conductors is an unpredictable effect, in some cases reducing the received signal and in other cases enhancing the signal due to the overhead Jine conductors' absorption and subsequent re-emission of the transmitted signal. Whilst it is very difficult to make exact prediction of this effect for a particular aerial location and transmitted signal, it can usually be overcome by repositioning the receiving-aerial. Electronic, telecommunications and data-processing euipment 11.10 Some types of electronic, telecommunications and data processing equipment may be unduly susceptible to RFI and magnetic fields because of their inherent nature. However, in practice it has been found that when constructed, installed and operated to the appropriate standards, there are no significant problems from overhead lines. However, it would be prudent to take into consideration the total electric, magnetic and RFI environment when considering any new computing or other electronic equipment. 11.12 Some types of data processing and similar equipment using display screens of a cathode ray tube (CRT) technology may experience some screen interference. This may typically affect both Visual Display Units (VDUs), the monitors mostly used with personal computers, and other VDTs. The effect is either to cause the screen to flicker or to wobble, at a frequency which is the difference between the 50 Hz power frequency and the screen refresh rate. Typically, CRT based displays are sensitive to extemal magnetic fields in excess of about 0.5 - 1 pT_ The contribution of the overhiead line magnetic field to this is unlikely to predominate outside 70 metres from the proposed centre-lines under maximum loading (4 kA per phase). In practice, this will affect few properties. Liquid crystal, plasma and other modem display screen technologies are virtually immune from any such problems. Adjacent services 11.13 Where overhead lines run adjacent to other services of a metallic nature, such as pipelines, telephone cables (especially in the case of a parallel run of some distance) some currents may be induced in or voltages appear on such services due to magnetic field induction or transient rise in earth potential. MITIGATION 11.14 The route for the transmission line would not be expected to cause interference to VHF/UHF radio or television services or to affect other electronic equipment. In the unlikely event of interference arising, adjustments to the aerial position and/or orientation should remedy the problem. In overhead line design and maintenance, a code of - practice for minimising RFI is normally observed. 11.15 In order to counteract situations where the magnetic field could induce perceptibly large voltages in metallic objects such as pipelines or telephone cables which run parallel to a transmission line, the appropriate authorities will be informned of EGAT's intention to construct the 500 kV lines, so that suitable mitigation measures can be taken. 11.16 In any case of screen interference reorientation or repositioning the monitor will often reiedy the probiem. Screened boxes of an aesthetically acceptable design are available in which to enclose monitors that are unduly susceptible or have to be in a fixed location. It would be prudent to consider the total electro-magnetic environment when considering the use of any new data processing or communications equipment. 11.17 In any instance where it is thought that the overhead line is causing interference, the assistance of EGAT should be sought. CONCLUSION ) 11.18 It is uniikely that the new overhead line will significantly worsen the electro-magnetic environment as compared with the existing line. However, it is possible that some properties could experience an increase in screen interference, for which remedial measures are easily available. 58 CHAPTER 12 CONCLUSIONS GENERAL 12.1 EGAT requested NGC to design a novel 500 kV overhead transmission line to replace existing 230 kV transmission lines in the Greater Bangkok Area. The main restriction imposed on the Project is that the new 500 kV lines should be built inside the existing 230 kV Rights-of-Way (ie a corridor of total width 40 metres). 12.2 The environmental impact of the Project as a whole (including dismantling the existing 230 kV lines and construction and operation of the proposed 500 kV lines) has been assessed. The conclusions of this process are summarised below. DESIGN OPTIONS 12.3 Four basic design concepts were considered before the conventional vertical steel lattice tower was chosen. This was preferred because of its maintainability, reduced foundation loads (less ground disturbance due to smaller foundations), longer span capacity (reduced visual impact due to fewer towers) and reduced EMF levels (due to phase LANDSCAPE AND VISUAL IMPACT 12.4 The proposed 500 kV transmission lines would pass through mainly open, agricultural or residential areas. This means that they would be visible over a considerable distance (up to 2 km if there are no intervening features). Howev.er, distant views of the 500 kV lines would be almost indistinguishable from views of the existing 230 kV lines. These are accepted by the community as a familiar part of the landscape, and therefore the visual impact of the Project would be small, and significantly less than the visual impact of a project which introduced a new line into a landscape without transmission equipment. SOCIO-ECONOMIC ASPECTS 12.5 Impacts during the construction period mainly consist of disturbance to farming activities in the Rights-of-Way. This disturbance can be minimised by maintaining good communication with affected landowners and considerate working practices. 12.6 Concerns during the operational period mainly relate to safety issues. Sufficient clearance would be provided to enable the land under and near to the new 500 kV transmission lines to be used normally. However, care is always needed when carrying long ladders or irrigation pipes or using high machinery under any overhead transmission lines. CULTURAL HERITAGE 12.7 The potential impacts from the Project consist of the loss of or damage to sites of archaeological importance and the adverse impact on the setting of cultural sites. sq 12.8 It is anticipated that the small increase in the size of the towers would not materially affect the setting of sites. Therefore, no known sites of cultural or historical interest would be affected more adversely than they already are by the existing 230 kV transmission lines. 12.9 There are no known archaeological sites along the existing Rights-of-Way, and it is un ikIcy that any wiUl be fouund. if significant remains were found, damage to the site would be limited as far as was practicable and a suitable level of site recording would be arranged prior to and/or during construction works. LAND USE 12.10 The main land use along the proposed routes is agricultural. Disturbance caused during dismantling the existing 230 kV lines and constructing the proposed 500 kV lines would be minimised by liaising with the local landowners and choosing appropriate working times. 12.11 Impacts due to the operation of the proposed 500 kV lines already exist along the chosen routes because of the presence of the existing 230 kV lines, and would be minimised by the re-use of existing tower sites where practicable. WATER QUALITY 12.12 The fact that the proposed 500 kV transmission lines are to be built in existing Rights-of- Way means that the impact on water quality in the area is expected to be small. This small impact will be further restricted by working in the dry season (when practicable) and by proper control of wastewater from the construction sites. 12.13 There will be no impact on water quality during the operational phase of the 500 kV transmission line project. This is because there are no emissions caused by the operation of a high voltage transmission line, and because care will be taken not to interfere with existing drainage patterns. FLORA AND FAUNA 12.14 The existing 230 kV lines are in an area which has already been developed for a mixture of residential, industrial and agricultural uses. Therefore, there is little wild fiora or fauna left in the study area. 12.15 TEAM's aquatic ecology survey indicated that the ecosystems present in the waterways which could potentially be affected by construction work are already poor. If the mitigative measures proposed in Chapter 7 (to maintain water quality) are applied, the potential disturbance to aquatic life is minimal. No impact is expected on aquatic ecology during the operational phase. 2.16 There is no evidence of an existing risk to birds caused by the operation of EGAT's existing transmission lines. There is therefore no reason to suppose that there will be a significant risk to birds posed by the proposed 500 kV lines. &D 2.16 There is no evidence of an existing risk to birds caused by the operation of EGAT's existing transmission lines. There is therefore no reason lo suppose "ha' 'here wili be a significant risk to birds posed by the proposed 500 kV lines. ELECTRIC AND MAGNETIC FIELDS 12.17 Bearing in mind that the standard ground clearance would be 16 metres, the proposed 500 kV transmission lines will produce power-frequency electric fields at 1 metre above ground level under normal operating conditions of significantly less than maximum design value of 15 kV/m and less than 2 kV/m at the edge of the Right-of-Way. The short section of quad circuit line may produce electric fields slightly in excess of 2 kV/m (2.16 kV/m) at the edge of the Right-of-Way under certain outage conditions. 12.18 These electric field strengths are less than those produced by EGAT's existing 500 kV line design which is already used in the Greater Bangkok Area. 12.19 The maximum power-frequency magnetic-field strength encountered at 1 metre above ground level will be less than 40 pT within the Right-of-Way and normally less than 15 pT at the edge of the Right-of-Way (remembering that the standard ground clearance would be 16 metres). The one possible exception is durng a single circuit outage on the proposed double circuit line, when the level at the edge of the Right-of-Way may reach 17.3 ,T. 12.20 These magnetic field strengths are less than those produced by EGAT's existing 500 kV line design which is already used in the Greater Bangkok Area, and the maximum levels are comparable to those produced by the existing twin-conductored 230 kV lines which are to be replaced. 12.21 Environmental problems due to electric and magnetic fields are therefore likely to be limited to interference with the image on cathode-ray-tube based VDUs operated close to the Right-of-Way. This is discussed in Chapter 11. AUDIBLE NOISE 12.22 The predicted audible noise performance of the proposed 500 kV line designs in foul weather is well within the level required by EGAT and comparable with that of existing, acceptable line designs of a lower voltage. Therefore, both the double circuit and the quad circuit line designs are environmentally acceptable from an audible noise point of view. ELECTRO-MAGNETIC COMPATIBILITY 12.23 It is unlikely that the new overhead line will significantly worsen the electro-magnetic environment as compared with the existing line. However, it is possible that some properties could experience an increase in screen interference, for which remedial measures are easily available. Li SUMMARY 12.24 The environmental impact of replacing certain existing 230 kV transmission lines in the Greater Bangkok Area with compact 500 kV transmission lines has been assessed. The additional environmental impact due to the proposed 500 kV transmission lines will be minimal, and environmental disturbance during the dismantling and construction phases can be minimised by caref,ul planning and good working practices. 12.25 It is better environmentally to increase the capacity of the existing network by replacing existing lines than by building separate, new lines. !~~~~~~~~~~~~~ ~ APPENDIX A REFERENCES CHAPTER 7: WATER QUALITY 7.1 Notification of the Ministry of Science, Technology & Environment, BE 2528 (1985) Royal Government Gazette, Volume 103, Part 60, April 15, BE 2529 (1986). CHAPTER 8: FLORA AND FAUNA 8.1 Limnology, R G Wetzl, CBS College Publishing, 1983. 8.2 Ecological Effects of Waste Water, E B Welch, Cambridge University Press, 1980. CHAPTER 9: ELECTRIC AND MAGNETIC FIELDS 9.1 Board Statement on Restrictions on Human Exposure to Static and Time Varying Electromagnetic Fields and Radiation, Documents of the NRPB, Vol. 4, No 5,1993. 9.2 Environmental Health Criteria 35: Extremely Low reuency (ELF) Fields, WHO, 1984. 9.3 Environmental Health Criteria 69: Magnetic Fields, WHO, 1987. 9.4 Interim guidelines on limits of exposure to 50/60 Hz electric and magnetic fields, International Non-Ionizing Radiation Committee of the-IRPA. Health Physics, Vol 58, No 1, (January) pp 113-122, 1990. See also: ICNIRP press release 1993. 9.5 US National Academy of Sciences (to be published) CHAPTER 10: AUDIBLE NOISE 10.1 Audible Noise as a Factor in Designing Transmission Lines, IEEE/PES Special Course: Corona and Field Effects of AC and DC High Voltage Transmission Lines, July 20-24, 1981. CHAPTER 11 : ELECTRO-MAGNETIC COMPATIBILITY 11.1 Radio interference characteristics of overhead power lines and high-voltage equipment. Part 3. Code of practice for minimising radio noise, CISPR 18-3 (under revision) APPENDIX B LIST OF ABBREVIATIONS AM Amplitude Modulation BOD Biological Oxygen Demand, measured in mg/i CISPR Comite International Special des Perturbations Radio6lectriques CRT Cathode Ray Tube DO Dissolved Oxygen, measured in mg/I EMC Electro-magnetic Compatibility EMI Electro-magnetic Interference FM Frequency Modulation ICNIRP International Commission on Non-Ionizing Radiation Protection !Ens%titu;!e of Electrica! and Elactronics ang;n.--- IRPA International Radiation Protection Association LW Vmdvge-' MOSTE Ministry of Science, Technology & Environment MW Medium Wave NESDB National Economic & Social Development Board NGC The National Grid Company plc NRPB National Radiological Protection Board RFI Radio Frequency Interference TVI Television Interference UHF Ultra High Frequency VDT Visual Display Terminal VDU Visual Display Unit VHF Very High Frequency WHO World Health Organization APPENDIX C GLOSSARY OF TERMS --AM (Amplitude Modulation) Radio transmission of signals by means of modulating the amplitude of the carrier wave. Corona discharge A form of limited electrical breakdown of the air, which can take place at surface irregularities on a high voltage conductor. This may be visible or audible and will emit electro-magnetic interference. CRT (Cathode Ray Tube) A display screen technology which uses a moving electron beam in a vacuum to cause a phosphor coated screen to fluoresce. dB(A) (A-weighted decibels) Decibels measured on sound level meter incorporating a frequency weighting (A-weighting) which differentiates between sounds of a different frequency in a similar way to the human ear. Measurements in dB(A) broadly agree with people's assessment of loudness. The background noise level in a livyng room may be about An dB(A), normal conversation about 60 dB(A), heavy road traffic at 60 metres about 80 dB(A) and the level near a pneumatic drill about 100 dB(A). Decibel The unit of measurement of sound pressure level. In most cases, noise levels will be A-weighted to compensate for the varying sensitivity of the human ear to sounds of different frequency. Diverter Material (eg preformed aluminium wire spiral) added to the shieldwire to make it more visible to birds. EMC (Electro-Magnetic Compatibility) The ability of electrical equipment to operate correctly in the presence of electric, magnetic or electro-magnetic fields generated by other equipment. Epidemiological Studies Epidemiology is the study of disease in a population, with the objective of identifying its cause or causes, particularly where the cause may be exposure to some environmental factor. FM (Frequency Modulation) Radio transmission of signals by means of modulating the frequency of the carrier wave. LN The level exceeded for N% of the measurement period, eg L90. 65