C1 E-235 VOL. 16 WANG NOI COMBINED CYCLE POWER STATION Environmental Impact Assessment Executive Summary 1. Background: The 1,800 MW Wang Noi combined cycle base load power station is fully constructed and operational on an area of 718 rai in. Tambon Khao Ngam and Wang Chula, Amphoe Wang Noi, Ayudhaya Province. The generating system includes 3 blocks of 600 MW generators. Each block is composed of 2 sets of 200- MW gas turbines and a 200- MW steam turbine. The EIA study report was approved by the National Environment Board in the meeting no. 5/2537 on June 8, 1994. The comnmercial operation of the power plant started in May 1998. Fuel: Natural gas will be supplied from the Gulf of Thailand and inland sources through a Petroleum Authority of Thailand (PTT) pipeline; there are no storage facilities on the plant site for natural gas. Distillate No. 2 oil (0.05 - 1.0% S, average 0.53% S) is used only as backup. The oil is delivered to the site by tank truck. the EIA for the pipeline has been done by PTT and approved by NEB. Water Supply: Makeup water for the power station is drawn from Khlong Raphiphat and a well. The power station demand would be only 6 % of the minimum (July 1992) recorded monthly flow of Khlong Raphiphat. A groundwater well on site serves only as backup and potable water supply. Condenser Cooling: A closed cycle condenser cooling water system is used. Air Pollution Control: Oxides of nitrogen are controlled in the combustion turbines by water injection in the first two blocks. the third block will use the dry, low Nox burner system. The stacks are equipped with on-line NOx monitors. Ambient Air Quality: Ambient air quality measurements have been taken every six months during commissioning of the first two blocks. Two sets of data are available: dry season, January - February, and wet season, May. Sulfur dioxide averaged over 24 hours ranged (0 - 6 ug/m3); that is, from undetectable to 2% of the national standard. The maximum NO2 measured at any receptor was 26 ug/m3, less than a tenth of the national standard, and a fifth of the World Bank standard. Tanking into account the planned expansion to 1,800 MW, the actual air quality monitoring results to date indicate the dispersion modelling was conservative. Dispersion Modelling Estimates, 1,800 MW: One year of meteorological data was used in the dispersion modelling. In case of diesel-fired (6 x 200 MW) combustion turbines, 1-hour maximum GLC of NO2 is 84.4 ug/m3 (worst case), below the national standard of 320 ug/m3. For SO2, the 24-hour maximum GLC is 10.5 ug/m3 (worst case); well below the national standard of 300 ug/m3, and the World Bank (NOx) guideline of 150 ug/m3. The annual average for SO2 is estimated at 7.6 ug/m3, well below the national standard of 100 ug/m3, and the World Bank guideline of 80 ug/m3. For the case of natural gas fueled (3 x 600 MW), 1-hour maximum GLC of NO2 is estimated to be 154.9 ug/m3 which is also below the national standard of 320 ug/m3. Wastewater: Sanitary wastewater and neutralized demineralization plant effluent are routed through a 4,000 m3 holding pond, which overflows to the retention pond (75,000 m3) onsite. Sanitary wastewater treatment consists of aeration, clarification and chlorination (calcium hypochlorite). The closed cycle cooling tower blowdown is discharged to the wastewater retention pond, along with effluent from the oil/water separator. An automatic w.ater quality sanmplinig siaLion is iocated at the outiet of the retention pond to Khlong 26. Water Quality: Plant effluent is pumped from a retention pond to Khlong 26, which also receives irrigation system drainage, domestic and agricultural wastes. Water quality monitoring at the raw water source, holding pond discharge and Khlong 26 has been undertaken every six months during project development. In 1997 the results of effluent water quality sampling during operation of the plant were within the effluent quality standard for irrigation canals of the Royal Irrigation Department. Solid Waste Disposal: Domestic solid waste, raw water and wastewater treatment sludge is taken off site and disposed by the Lam Ta Sao sanitary district in Amphoe Wang Noi. Fuel Oil Storage: Oil storage is in two 29.45 million liter tanks. The oil storage facilities are is built to ASTM and API standards. The area surrounding the fuel oil storage tanks is designed to contairn oil spills resulting from equipment failure or leaks occurring during normal operations. The oil containment is berms constructed of retaining walls built of reinforced concrete. Fuel oil piping is routed above grade on pipe racks in order to facilitate detection and repair of leaks. If for any reason the pipe must be located underground, it is placed in a concrete trench which is drained to the oil/water separator. The facility Emergency Plan covers fire and explosion. A spill prevention, control and response plan will be added to the site Emergency Plan, and added to the emergency response drill routine. Hazardous Chemical Containment and Storage: All chemical storage tanks, solution tanks, and chemical feed pumps are located on curbed concrete containment areas drained through separate chemical waste collection piping to a neutralization basin or a chemical waste collection sump. A curbed concrete area is provided with a chemical-resistant coating suitable for the particular service. As a minimum, the combined volume of the curbed area and the associated neutralization basin or waste sump is adequate to contain the entire volume of the largest single tank served. A spill prevention, control and response plan wil4 be added to the site Emergency Plan, and added to the emergency response drill routine. Chlorine: The chlorination station for the condenser cooling water is equipped with a leak detection and alarm system, wind sock, leak stemming gear and personnel protective equipment, including self contained breathing apparatus. A chlorine leakage response scenario will be added to the plant Emergency Plan, and leak response drills undertaken as part of the emergnecy response drill routine. Analysis of Alternatives: Alternatives analylzed for the project included choice of technology, site selection, water sources, wastewater treatment schemes and choice of receiving waters. Environmental Management and Monitoring: An environmental management unit will be instituted at the power station, responsible for carrying out the monitoring plan, reporting nerformance, and follow up with management. The environmental unit would report directly to the plant manager. The environmental monitoring plan covers the construction period as well as ongoing operations, and includes: effluent and surface water quality; noise; groundwater hydrology and quality; aquatic ecology; solid waste management; transportation; socio-economic indicators; public health; and occupational health and safety. The monitoring plan includes continuous air emissions and ambient air quality monitoring during operations. An abbreviated summary of impacts, mitigation and monitoring is shown below. WANG NOI COMBINED CYCLE POWER STATION SUMMARY OF IMPACTS, MITIGATION MEASU]RES AND MONITORING PROGRAMS Environmental Environmental Impacts Mitigaition Measures Monitoring Programs Resources/Values Physical Environmental Resources Air Oualitv Operation Phase - Stack height of CT units - Continuous Monitroing of NO2, - At the first stage, at CT stack should be kept at 35m SO2 and wind speed and direction height of 35 m, GLC of SO2 minimum. at 5 stations, around the project site is Continuous Monitoring fo stack acceptable. - Stack height of HRSG should gas for SO2 and NO2 at CT and - At the final stage, at HRSG be kept at 35 m minimum. HRSG Stack height of 35 m. GLC of SO2 and NO2 is acceptable. Noise - No mitigation measure is Operation Phase required. - No Monitoring program is - Noise livel at the distance of required. 60,120 and 200 m away from the plant center will reduce to 49 43 s-nd 39 dBA thuq cynusing no effects to nearby community. Surface Water Operation Phase - Cooperation of EGAT with - Water situation in relation to the Hvdrology - Impacts due to serious RID for peoper water Plant must be closely monitored. shortage of water in some management must be carried periods. out. - construction of a raw water reservour for 5 - d storage in necessary._ Surface Water Qualit-y - Treatment of holking pond - Monitroing of water quality in Operation Phase effluent to reduce SS, Khlong Raphiphat and Khlong 26 - Discharge of effluent of 5A conductivity and TDS is for temperature, pll, conductivity, 197 1/min (diesel oil fuel) and required. trubidity, SS, TDS, alkalinity, 4,9161/mon Zgas fuelX into - Treated effluent should partly hardness, DO, BOI), H2S and Khlong 26 will affect be recycled or reused. grease & oil must be conducted downstream water quality in - Study on toxicelogican effects twice a year in rainy season terms of SS, TDS, hardness, of chemical susing in cooling (October) and in dry season sulfate, conductivity and system on in digenous plant and (April). coplymers using in cooling aqutic organisms is required. system. - Additional monitoring of water quality for Pb, Cr, (Cu, Zn, Hg, Ni - Contamination of chemical s and Cdin dry season and pesticides may be harmful to aquatic lives. inrainy season must be conducted. Environmental Environmental Impacts Mitigaition Measures Monitoring Programs Resources/Values Groundwater Operation Phase - Withdrawal at optimal rate is - Mintoring of land subsidence is - Amount of water for domestic necessary to preven land required. supply is within the yield of subsidence. groundwater Wells in this area. - Monitoring of drawwown - Montoring of drawdown is Theredore, no impact is from test wells is required. expected. recommended. - Groundwater quality is - Water for (drinking purpose - Monitroing of groundwater suitable for domestic use but must be treated. quality twice a-year is must be treated, if used for - Monitoring of groundwater recommended for pH, drinking quality is recommended. conductivity, turbidity, dissloved - No mitigation measure is solids, suspended solids, alkalinity required hardness calcium, iron, magnesium, chloride sulfate and nitrate. Aquatic Ecology and Operation Phase - A fisheries management unit, Fisheries - At the raw water intake pump fish stockin,g program and station, young fish ans fish eggs control of aquatic weeds in will be pumped into the intake. Khlong Raphiphat and Khlong Degree of mortality depends on 26 should be established. design of intake structure. Foloating weeds will also affect the intake. - Large volume of water discharged froin the[ower plant will increase water inKhlong 26 for natural fisheries and aquaculture. -Changes in flow regime of Khlong 26 will alter group composition of aquatic or anisms_ Water Use Operationn Phase. Khlong Raphiphat, A. Nong Khae, Saraburi - The Plant utilizes water of about 1.25 MCM/month from Khling Raphiphat at Phra Sri Silp Regulatior. The amount of water required is about 6% of the total runoff in Khlong Raphiphat during dry season (21 MCM/monthX. In addition, grounwater willb ewithdrawn as - Cooperation between EGAT a back-up for construction and RID is reconmmended activits. No impact is then expected. - In case the pasak project is completed, runoff in chao phraya will be increaed by 50% thus no impact is expected. Environmental Environmental Impacts Mitigaition Measures Monitoring Programs ResourcesNalues Public Health I Operation Phase - Maintenance worders and - Regular medical surveilance is operators will be the high risk to ve providd for 'these group to working accidnets dur personne. to improper management, - Stringent supervision and fatique, etc. control and proper management - Transport accients are lidely to are necessary to minimize the occur accidents. The medical center - Laboratory personnel will be must be established. subject to health gazards from - Safety regulations must be chemical sin terms of shin provided within the plant and irritation. Long term exposure personnel must be aware of will lead to respratory tract safety. disease and defection of kidney - Air quality muste be and liver. maintained within the national ambient air quality standard and must be monitored regularly. Occupational Health - Noise from operation of - Minatenance of machine - Monitroing of noise at generator and machine such as gas turbine and should be done regularly. and instrument air unit should be Safet-y intake area will not exceed 85 - Insulation of turbine casing done once a year. dBA which commplies with the should be replaced periodically standard of Ministry of Interior to reduce noise and vibration. (90 dBA). Thus no serious - Control roon should be effect from noise is expected. provided in case of continuous exposure to noise. - Ear protection equipment should be provided for employees. - Monitoring fo nise should be conducted regularly. - Test for hearing loss should for - Hearing loss should be tested worders being exposed to loud for worders who work in noisy noise. areas. - Since the machine tha tcauses - Heat insulation is provided. - WGBT should be monitored heat is covered in the enclosure once a year therefore such heat will not cause any adverse health effect - Proper management and close to workers. wupervision should be - Sickness and accidents of all - Accidents may occur from implemented. levels must be recorded ussafe acts of workers throughtout the course of esppecially during maintenance. operation. If preventive measures are effictively implemented and - Regular check--up of pope followed up, impacts will not be conditions is recommeded. serious. - Continouous gas detector with - Leakage of gas popeline may on line system should be installed cause serious damages. for monitoring purpose. - Monitoring of noise at generator and instrument air unit should be done once a year. Environmental Environmental Impacts Mitigation Measures Monitoring Programs Resources/Values I_ Aesthetic Values Operation Phase - provision of green belts and andTourism - Smoke from the power plant areas should be deone. will reduce aesthetic quality of - Local agencies should control the site. establishment of housing - The power plant will induce estates and factories housing and indutrial development in the area. The Effluent Quality of Wang Noi Combined Cycle Power Plant Compared with World Bank Guidelines Parameters Unit Power Plant Effuent Thai Standarda World BankGuidelines Renmarks (Maximum Value) (Maximum Value) (Maximum Value) pH 6.5-8.5 6.5-8.5 6-9 Daily - Neutralization Basin TSS mg/l 30 30 50 Daily - Raw water treatment BOD mg/l 20 20 Daily - Wastewater Treament Oil & Grease mg/l 5 5 10 Daily - Oil Separator Free Chlorine mg/l 1 1 Daily - Cooling Tower Outlet Residue Chlorine mg/i 0.2 Temperature Increase 0 C _ < 3b < 3 Closed cycle Cooling Tower, TDS mg/I 1,300 1,300 Effluent temp. equal to Ambient Aluminium mg/I 0.5 water temp. Arsenic I mg/l 0.25 0.25 Cadmium mg/l 0.03 0.03 Chromium mg/l 0.3 0.3 Copper mg/l 1 1 Note: a: Effluent Water Quality Standard for Irrigation Canals, Royal Irrigation Department. b: Temperature Inerease is based on Surface Water Quality Standard: Notification of National Environment Board N4o. 8 B.E. 2537 (A.D. 1994) Maximum Ground Level Concentration Estimates For Wang Noi Combined Cycle Power Plant Project. Pollutants Max GLC Thai Ambient Air World Bank Guidelines Remarks (ugfm3) j Quality Staindard (1994) (1997) { S02 - hr. 7 780 -24 hrs. 41.5 300 150 -Annual Ave. 5.6 100 80 NOv - I hr. Diesel 142 Gas 190.3 320 - -3 hrs. Diesel 74.2 Gas 103.5 150 -24 hrs 80 - Annual Ave. TSP - 24 hrs. PM1o 120, TSP 330 PM1o 150 - Annual Ave. PM10 5, TSP 100 PMI0 50, TSP 80