| With the development of society,the increasing scale of urban construction,the impact of infrastructure projects on the environment has become more and more serious,how to reduce the impact of infrastructure projects on the urban environment has become an important issue.As a policy of China's environmental management system,basic purpose of environmental impact assessment is to carry out environment protection policy and seriously implement "prevention first and combining prevention and treatment,comprehensive utilization" environmental management approach,to encourage the consideration of environmental factors in planning and decision-making,finally make human activities more compatible to the environment.In this paper,based on the characteristics of infrastructure projects,taking the characteristics of the local environment and environmental protection targets into account,on the basis of the investigation and collection of air environment,sound environment and landscape environment and effective background information of the residential areas,study the pollution that exist during infrastructure,Construction,operation period,forecast analyze the potential impact of the infrastructure projects on the environment, air,water environment,sound environment,solid waste,and proposed environmental protection measures and pollution mitigation measures for infrastructure in residential areas. Main conclusions of the study are as follows:1.Present Environmental Quality of Construction areaXi'an ambient air quality in 2006 is with an annual average of SO2 for 0.055mg/m3,with reaching standard rate of 94.16%;the annual average of NO2 is 0.042 mg/m3,with a reaching standard rate of 99.86%;annual average of PM10 was 0.132 mg/m3,exceeding National ambient air quality secondary standards for 32.00 percent,daily average concentration is in the range of 0.020～0.392 mg/m3,with the maximum exceeding multiple of 1.61,the reaching standard rate is 71.28 percent.In the first quarter of 2007,the city's SO2,NO2,PM10 have declined compared to the same period last year,the decreasing extent respectively reached 21.81 percent,16.39 percent,and 8.23 percent.And monitoring spot of the high-voltage switchgear plant which is near the proposed project site in the first quarter of 2007 had the average of PM10 of 0.151mg/m3,with the exceeding rate of 42.22 percent.PM10 of the city in 2007 was with the average of 0.145mg/m3,with an exceeding rate of 37.78 percent which showed air quality of high-voltage switchgear plant is worse than the city's. This may indirectly indicate that the main pollutant in proposed project is PM10.As the Water Transport of Grain drainage which accept the sewage water of Xi'an,water quality of its section is ClassⅤ.The main pollutants of petroleum with a exceeding multiple of 5.56 times,NH3-N over 17.52 times,COD exceeding 6.5 times.As the Water Transport of Grain drainage goes into the Weihe River,serious water pollution is caused in the Weihe River. Water quality of Gengzhenqiao section of Weihe River is ClassⅤ,petroleum over 25.42 times,NH3-N exceeded 8.93 times,COD exceeding 3.8 times.North factory sector of construction projects,noise of day and night both exceed "urban regional environmental noise standard" standard 2,the main source of noise is traffic noise from 26-wai Street;east and west and the south side of projects,the noise of day and night both meet the "urban regional environmental noise standard" standard 2.Traffic noise of Wei 26 Street day and night both exceed GB3096-93 "urban regional environmental noise standards" standard 4.2.Environmental impact forecast of Construction projectThe main source of pollution emissions during Construction project running period is automobile exhaust from underground parking lot,domestic waste gas and the boiler exhaust emissions.Projects includes an underground parking lot,car exhaust produced annual CO of 15.53t/a,CH for 2.22t/a,NOX for the 1.49t/a.District residents use natural gas which has a small environmental impact on the atmosphere.Heating with gas-fired boiler,in the heating season will produce air pollution,but with the use of natural gas as fuel,the extent of the impact on the environment will not be too great.Daily Sewage generated of the project is about 439.36 m3/d,resulting in about annual production of 160,400 m3/a,mainly domestic water.After septic tanks treatments,waste water discharged into the municipal sewage pipe network is with actual emissions of 128,300 m3/a.The main noise is from water pumps,standby generators and running fan noise,the general nature of sound source is mechanical noise and aerodynamic noise,the sound level is at 70～95dB(A).High-noise devices are installed in the basement,which will do little effect on the in-house administrative center and the surrounding environment.After the completion of construction projects,solid waste generated mainly would be solid waste,commercial garbage and dead plants.A refuse collection point is to be built,a closed device used to collect garbage,garbage that day removed the same day,unified by the sanitation department to the designated garbage dump landfill.Refuse collection points will not have an impact on the surrounding environment.3.Environmental Impact Analysis of The construction phaseConstruction dust pollution is mainly 200m leeward,pollution exceeding standards mainly about 100m leeward.Construction dust may have a certain impact on leeward ostrich king building.Daytime construction noise could meet the noise standards generally,the night construction,most of the noise will exceed the standards,so the noisy equipment running time of this project should be strictly controlled,the construction is strictly prohibited at night (10:00 pm to 6:00 am),and to avoid disturbing the residents.4.Environmental protection measuresAutomobile exhaust emissions in underground parking lot should be through the ventilation system.With height of 2.5m of discharge pipe,to ensure the air changes of the underground garage(no less than 6 times/hour) to ensure that the concentration of pollutants in the underground garage meet GBZ2-2002 limits.Muffler is installed to the fan of the underground garage,noisy equipment such as water pump equipment,should be set underground,to take the basis of shock absorption,sound insulation, sound absorption materials,double-soundproof windows are installed for residential on the side which is on the side of the road,whistle is prohibited in the district,transparent cover is set for the underground garage entrance.Sewage treated by septic tanks,and then go into the municipal sewer network,and then enter the fourth Xi'an sewage processing plant.5.Pollutant total control proposalsTake the proposed project features and characteristics of the sewage into consideration; the total amount of pollutant emission control factor of the project is COD.The proposed targets for total control of COD is not higher than 35.92t/a. |
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