TaiBasin Urban Environment Project
Environmental Assessment Summary Report
for
Wuxi Hiushan Phase-III Wastewater Treatment Works
December 2008
Guangzhou Zhonglu Environmental Protection Company
Table of Content
1.Introduction------
2.EA Basis------
2.1Laws and Regulations
2.2Applicable Standards
2.3World Bank Safeguard Policies
3.EA Coverage------
4.Project Description------
4.1Project Constituents
4.2Influent Quality Estimate
4.3Process Description
4.4Wastewater Flow Projection
5.Environmental Baseline------
5.1General Setting
5.2Climate and Air Quality
5.3Acoustic Environment Quality
5.4Surface Water Quality
5.5Hydrology
5.6Water Supply and Wastewater Treatment
5.7Socio-economic Condition
6.Pollution Loads Reduction------
7Analysis of Alternatives------
7.1 Introduction
7.2 Wastewater Treatment Process Options
7.3Sludge Disposal Options
8.Environmental Impacts and Mitigation------
8.1Impacts in Construction Phase
8.2Positive Impacts
8.3Sludge Disposal Impacts
8.4Air and Odor Impacts
8.5Noise Impacts
9.Environmental Mitigation Measures------
9.1Design Phase
9.2Construction Phase
9.3Operational Phase
10.Environmental Management and Monitoring Plan------
10.1Environmental Management
10.2Environmental Monitoring
11Public Consultation and Information Disclosure------
11.1Process
11.2Public Meetings
11.3Public Opinion Survey
11.4Results of Consultation
11.5Information Disclosure
12Conclusions------
1.Introduction
The Wuxi Hiushan Third Phase Wastewater Treatment Works is proposed to join the Tai Basin Environmental Project partially financed by the World Bank using the remaining loan at an amount about USD 6 million. The World Bank loan for the Tai Basin Environmental Project became effective on 2005, which is intended to contribute to the attempt to tackle the severe surface water pollution within the TaiBasin through a series of interventions such as provision of domestic wastewater treatment capacities and river dredging.
Officially regarded as one of the three most polluted lakes, TaiLake has experienced more and more severe pollution accidents, caused by uncontrolled discharge of wastewater from both urban wastewater and agricultural runoffs. In 2003 the State Council approved the “Tenth Five Year Plan for Tai Bain Water Pollution Control” (the Plan hereafter) which calls for construction of 81 wastewater treatment plants with a combined capacity being 3.91X106 m3/d within the basin. This Plan also defines a technology policy to be adopted by the wastewater treatment plantso as to remove the nutrient loads (generally are Total Phosphorous and Total Nitrogen) that trigger the algae blooming frequently occurred in TaiLake. In response to the Plan, Wuxi Government has developed an Implementation Plan for the ‘Tenth Five Year Plan for Tai Bain Water Pollution Control’ in Wuxi that requires phased construction of Wuxi Huishan Wastewater Treatment Works at a medium-term capacity of 50,000m3/d to be reached by the end of 2010. The first two phases of the Wuxi Huishan Wastewater Treatment Works have been successfully completed under the Tai Basin Environmental Project to a capacity of 25,000 m3/d.
An environmental impact assessment (EIA) report and environmental management plan (EMP), collectively known as the EA documentation, has been compiled by the Guangzhou Zhonglu Environmental Protection Company, with the assistance from the project DRA consultant, Mott MacDonald. This document is a summary of the EA documentation.
2.EA Basis
2.1Laws and Regulations
The laws and regulations applied in the EA are as follows:
Environmental Protection Law, P.R.C., 1989;
Water Pollution Prevention law, P.R.C., 1996;
Air Pollution Prevention law, P.R.C., 2000;
Noise Pollution Prevention Law, P.R.C., 1996;
Solid Waste Pollution Law, P.R.C, 1995;
Environmental Impact Assessment Law, P.R.C., 2002;
Regulations for Environmental management of Construction Projects, State Council Circular 253;
Regulations for Water Pollution Control in TaiBasin within JiangsuProvince;
Technical Guidelines for EA.
2.2Applicable Standards
The standard of primary concern for this project is the standard for treated effluent of wastewater treatment plant. To reverse the trend of enrichment in the TaiLake, the Jiangsu Provincial Environmental Protection Commission and Jiangsu Provincial Quality Supervision Bureau jointly issued a local standard-Discharge Limits for Primary Pollutants from Municipal Wastewater Treatment Plants and Key Industries, DB 32/1072-2007. This local standard requires that the most stringent limits, Class 1 A,of the national effluent discharge standard be adopted by all the urban wastewater treatment plants in the area within TaiBasin in JiangsuProvince. The national standard for Pollutants Discharge Limits for Municipal Wastewater Treatment Plants (GB 18918-2002) is summarized below.
Table 2-1Pollutants Discharge Limits for Municipal Wastewater Treatment Plants (GB 18918-2002) unit: mg/l
No. / Pollutants of Primary Concern / Class 1 A1 / COD / 50
2 / BOD5 / 10
3 / SS / 10
4 / TN / 15
5 / Ammonia-Nitrogen / 5
6 / TP / 0.5
The other standards to be applied in this EA including:
Ambient Air Quality Standard, GB 3095-1996;
Surface Water Quality Standard, GB 3838-3003;
Acoustic Environment Quality Standard, GB 3096-2008; and
Odor Discharge Standard, GB 14554-93.
2.3World Bank Safeguard Policies
After screening of the ten safeguard policies of the World Bank, it is determined that only the OP 4.01 Environmental Assessment is to be triggered by this project. As the project is to be constructed within the boundary of the existing plant for which the land was acquired under the first two phases of the works, the Involuntary Resettlement (OP4.12)is not to be triggered.
3.EA Coverage
According to the TOR, the EA covers the area from the joint of XibeiCanal and XichengCanal where the treated effluent will be discharged to the joint of XichengCanal with Xishan District.
4.Project Description
4.1Project Constituents
As the design of the initial phase of the wastewater treatment works has taken into account the need to increase the capacity to 50,000 m3/d, conventional structures within the existing works and the interceptors are designed to be capable of accommodating the increased portion of wastewater flow to be introduced by the third phase. The components of the project are summarized in Table 4-1 below and the location of the Huishan WWTP and the pumping stations are shown in Figure 1:
Table 4-1Summary of Project Constituents
Description / Service Scope- Capacity: 25,000 m3/d
- Provision of screens and pumps for three existing pumping stations;
- Construction of a primary settling tank, A2/O reaction tank, sand filter tank, blower house, backwashing tank, backwash wastewater storage tank, UV chamber, and sludge thickening tank
- 50 industrial discharges
- 20 km2 urban area
- 88 thousand population
4.2Influent Quality Estimate
As the industries that are to discharge wastewater into the project are required to install treatment facilities which are designed to meet the national standard for industrial wastewater discharge into municipal sewers. The local EPB willenforce such requirement to ensure the safe operation of the project. Based on the operational experience of the first two phases and the specific features of the service area, the influent wastewater quality for this project is estimated as follows:
Table 4-2Influent Quality Estimateunit: mg/l except for pH
Pollutant / COD / BOD5 / SS / NH3-N / TN / TPInfluent concentration / 500 / 300 / 400 / 35 / 40 / 8
4.3Process Description
The design comprises screening and grit removal followed by anA2/O biological reactor (Anaerobic - Anoxic- Aerobic) and secondary clarification, and tertiary sand filter. The sludge produced will be thickened by gravity. Thickened sludge will then be chemically conditioned and finally dewatered to produce sludge cakes with approximately 20% dry solid. Final effluent will be discharged into the XibeiCanalafter UV disinfection.
4.4Wastewater Flow Projection
The service area of the project has a separate sewer system. Estimated water demand is based the medium term master plan of Wuxi with a planning horizon to 2015. Various data on per capita consumption for domestic water are adopted for the people living in different areas, the common living area and the expensive living area respectively. The industrial dischargeof wastewater within the service area is obtained from these industries. 88% is used as a conversion coefficient to convert water demand to wastewater generation from municipal sector.The wastewater flow projection is summarized in Table 4-3 below.
Table 4-3 Summary of Wastewater Flow Projection unit: m3/d
Sector / Water Demand / Wastewater flow / Total wastewater flowDomestic and Municipal / 18649 / 16410 / 22098
Industrial / - / 5695
5.Environmental Baseline
5.1General Setting
Huishan District is located in the north of WuxiMunicipality, 129 km from Shanghai and 177 km from Nanjing. The general topography is very flat with an elevation averaging 2-5 m. This area has a rich and complex geology. The Quaternary fluvio-lacustrine and glacial sediments form the most important groundwater aquifers in the area. They include gravels, sands and silts up which are intercalated with clays deposited during three marine transgressions.
5.2Climate and Air Quality
Huishan District is located in the sub-tropicalarea where a maritime monsoon climate dominates. The climate is characterized by distinct seasons and rich rainfall. Average annual precipitation is 1,000mm.The annual temperature averages 15.5OC.
The project is located within a new developed area where cleaner fuels are required to be used in the industries. An air quality monitoring program conducted from Oct. 6 to Oct. 10 2008 confirmed the high air quality of the site where SO2, NO2 and TSP can meet the Class II of Air Quality Standard (GB 3095-1996)while the NH3 and H2S can meet the standard for residential area (TJ 36-79)
5.3Acoustic Environment Quality
The acoustic environment quality is fairly good in the project site. A noise monitoring program was conducted on Oct 6 through Oct 7 2008. The monitoring results indicate that the Class II of the Acoustic Environment Quality can be reached at the site。
5.4Surface Water Quality
Currently the XibeiCanal receives the domestic wastewater and agricultural runoff from the south side of the river, although the wastewater from the north side will has been intercepted by the wastewater treatment works. A surface water quality monitoring program, carried out during the period from Oct. 6 through Oct. 8, 2008, indicates that some of the pollutants concentration of primary concern, such as COD, NH3-N and TP can not constantly meet the respective standard while BOD5 failing to meet the standard throughout this monitoring period.
The XibeiCanal is a tributary of WangyuRiver which discharges into the TaiLake. Water quality objective for the Xibei Canal is required to meet the Class IV of Surface Water Quality Standard (GB 3838-2002) by 2010 and the Class III by 2020. This proposed project is mainly designed to improve the water quality in the XibeiCanal, which is currently receiving large amount of agricultural runoff and domestic wastewater flow.To achieve the above water quality objectives, Wuxi needs to remove COD 823t/a by 2020
5.5Hydrology
River system is well developed in the project area. There are totally 129 rivers in Wuxi which are discharged either by the JinghangGreatCanal or XichengCanal. These rivers discharge to the TaiLake, or to the Yangtze River through the WangyuRiver, or the JInghangGreatCanal.
The water quality in the upstream section of the XichengCanal and the JinghangGreatCanal is below the Class V standard. In addition, the flat terrain and the clogged river courses in Wuxi often lead to very slow flow velocity, hence very poor self-cleaning capacity. As a result, the water quality in the XibeiCanal varies between Class Iv and V throughout the year.
The XibeiCanal is an important waterway for navigation. It runs from XichengCanal to join the WangyuRiverin Suzhouwith a total length of 37.4 km and an averaged flow rate of5.57 m3/s.
5.6Water Supply and Wastewater Treatment
Although the water resource in Wuxi is abundant, the poor water quality has forced the city of Wuxi to abstract drinking water from TaiLake where the water quality is being deteriorated. In 2007, the severe outbreak of algae blooming in the lake made the cities that abstract drinking water from the lake close their water abstraction points, causing a drinking water crisis in the cities including Wuxi.
The existing water supply capacity of Wuxi is 1.38 million m3/d. To guarantee the drinking water safety, Wuxi is implementing a phased water transfer work that abstract water from the Xicheng Canal at a total capacity of 0.8 million m3/d.
Wuxi has a limited domestic wastewater treatment capacity. The total domestic wastewater treatment capacity is1.05 million m3/d which treats 55.04% of the domestic wastewater flow. The industrial wastewater flow in the city of Wuxi57% is treated by the industrial wastewater treatment plants.
5.7Socio-economic Condition
The Huishan District, where the project is located, lies within the Yangtze Delta which is the most prosperous area in China. The key indicators of the socio-economic condition of the Huishan District are summarized in table 5-1 below.
Table 5-1Key Socio-Economic Indicators of the Huishan District
Parameters / IndicatorsPopulation / Urban population: 0.2995 million
total population, 0.3989 million
population density: 1,219/km2
Land / agricultural land, 158.78 km2
total land,327.12 km2
Urbanization / townships/counties: 7
Agriculture / major crops: wheat, rice, vegetables, fruits, etc.
net annual income per capita in agricultural sector: 10,450 RMB
Industry / major industries: textile, dying, machinery, etc.
total industrial output: RMB 82 billion
6.Pollution Loads Reduction
The main pollution loads reduction by this project and its relation with the Tai Basin Environment Project are given in Table 6-1 below.
Table 6-1Pollution Loads ReductionUnit: ton/year
Phase of works / Pollution loads reductionCOD / NH3-N / TN / TP
First two phases / 2053.1 / 191.7 / 146.0 / 18.2
This project / 2053.1 / 191.7 / 146.0 / 18.2
Sub-total / 4106.2 / 393.4 / 292.0 / 36.4
TaiBasin Environment Project / 47,000.0 / 2200.0 / N/A / 200.0
% by Wuxi Huishan WWTW / 8.8% / 17.9% / - / 18.2%
7Analysis of Alternatives
7.1 Introduction
During project development, various alternatives have been screened and compared with technical, economic and environmental criteria. In terms of the environmental assessment of alternatives, the primary objective was to identify and adopt options with the least adverse environmental impacts. The evaluation and comparison has included the following component options:
Wastewater treatment process;
Sludge treatment and disposal, including sites for the final disposal of sludge; and
The scenario of with and without the project.
7.2 Wastewater Treatment Process Options
The priority for wastewater treatment in the TaiBasin is the removal of pollutants that impact adversely upon the surface water quality. The most critical pollutant in this context is organic matter expressed as COD, TN, TP and NH3-N.
As required by the Bank, the following criteria formed the basis of identifying the most appropriate wastewater treatment proposal.
Comply with the required wastewater discharge standard of Class 1 A;
Appropriate in respect of local conditions;
Proven in operation at or close to the scale proposed;
Capable of supporting competitive bidding;
Representing the least cost option.
Two alternative processes were considered for the secondary treatment of wastewater and compared against the above criteria. The two process options are the modified SBR and modified A2/O with the latter being identified as the preferred and least cost option for secondary wastewater treatment.
As wastewater is treated, solids are removed and become sludge that needs proper disposal. Sludge will be treated by gravity thickening and dewatering by means of belt press or centrifuge. More complex is digestion of the sludge in large vessels, either aerobically or anaerobically. Thickening produces sludge with 3% solids content, which is still a liquid. Dewatering produces a semi-solid sludge with about 20% solids content, which can be handled by spade. Given the features of the wastewater treatment technology, the amount of sludge to be produced is expected to be very small, less than 4 tons per day. Digestion of the excess sludge will release phosphorous from the sludge to the supernatant. In addition, digestion may result in complex of operation of the wastewater treatment plants at such a small scale, which will lead to poor financial viability of the plant.
7.3Sludge Disposal Options
Landfill and use for brick making were considered as the options for disposing of the excess sludge. Landfill is considered as the least-cost means for the final disposal of sludge, however the addition of sludge to an existing landfill site may reduce the service span and often result in alternation of the operation procedure of the landfill, causing difficulties in operation of the landfill. Thus the Wuxi EPB has developed a municipal sludge disposal plan which requires that the municipal sludge generated by WWTWs be hauled to a dedicated disposal center where the sludge will be incinerated and used as additives for brick making at site.
To minimize the potential impacts during hauling of sludge to the disposal center, two alternative routes were considered.
8.Environmental Impacts and Mitigation
8.1Impacts in Construction Phase
Project construction activities will generate the following adverse impacts:
Airborne dust, mainly due to construction vehicle movement, land preparation, and materials handling. Under the condition of 5 m/s wind speed, the dust concentration in 150 leeward of the construction site will be 0.49 mg/m3, which can not meet the Class II of Ambient Air Quality. However, if the site is fenced, the impact of noise will be limited to less than 90 m under the same meteorological condition.
Vehicular emission from the construction vehicles will impact the area 100 m leeward of the construction site and route under the condition of 2.5 m/s wind speed. After the site is fenced, the emission impact will be limited to less than 70 m under the same metrological condition.
Noise, from construction equipment and vehicular movement. The noise, as high as 105 dB(A), could travel as long as 250 in night in the open fields around the source before it is reduced to the level that can meet the acoustic quality standard, affecting residents of nearby villages. As the residential houses are far away from the site, the noise impact will not cause disturbance on the residential area.
Waste discharge from construction camps. The discharge of sewage from construction camps will create temporary pollution sources to the surface water environment. The construction camps will be sources of other pollutants such as sediment-laden stormwater discharges, solid waste and waste oil from machinery maintenance.
8.2Positive Impacts
This project will help enhance the trend of water quality improvement in the local water environment and sub-sequentially help reduce the pollution loads, particularly the nutrients, to the TaiLake. The water quality objective of the Xibei river is to achieve Class IV by 2010 and Class III by 2020. Implementation of this project will contribute towards achieving this objective.
A surface water quality model recommended by the Technical Guideline is used to forecast the water quality of the XibeiCanal which receives the treated effluent from the project. The result of the model indicates that after the project is operational in 2010 and in a constant yearly averaged flow rate, the concentration of COD, NH3-N and TP will be reduced by 2.5 mg/l, 0.25 mg/l and 0.02 mg/l respectively at the control section of the canal. Table 8-1 shows the trend of water quality improvement in the XibeiCanal.