The HZMB project will have numerous consequences on the abiotic environmental aspects of the Hong Kong and Pearl River regions. Pollution impacts include alterations in air quality, noise levels and water quality. The temporary construction phase as well as the long-term operation of the new infrastructures have been analyzed in terms of potential environmental issues and mitigation measures that should be taken to reduce impact.
Air Quality
The main source of air pollution caused by the construction phase consists of dust emissions from excavation and concrete batching plants. Vehicular emissions from road traffic constitute a pollution source due to the operational phase. Nitrogen dioxide and suspended respirable particles, for instance, were expected to be released by transportation vehicles.
The image on the left shows the new boundary-crossing facilitites area that will require reclamation work. Construction operations involve air quality impacts.
Assessment Methods
"Air sensitive receivers" that are at risk of being impacted by air pollution were identified. These include several institutions such as residences, hotels, hospitals, offices, factories and educational institutions. The study areas included air sensitive receivers located at a minimum distance of 500 meters from the boundaries of the construction sites. The air quality standards were those stated by the "Hong Kong Air Quality Objectives".
The tool used to assess impacts of the construction phase was the "Fugitive Dust Model". This model permits to compute air dispersion as well as dust particle size distribution.
For the operational phase, an air quality prediction model, the "Pollutants in the Atmosphere and the Transport over Hong Kong" model, was used to evaluate nitrogen oxides emissions for the following years:
Assessment Results
After the assessment of dust emissions from the construction phase, results showed that the total suspended particulate matter hourly concentrations exceeded the acceptable levels for several air sensitive receivers. Thus, several mitigation measures were demanded so that dust levels would comply with the standards. One method consists of watering dusty construction material and wheel-washing of vehicles on a basis of 8 times a day.
According to the results of the operational phase assessment, nitrogen oxides concentrations in the atmosphere would not exceed the standards. Therefore no residual impacts on air quality due to the operation of the infrastructure were expected.
The image on the left shows the new boundary-crossing facilitites area that will require reclamation work. Construction operations involve air quality impacts.
Assessment Methods
"Air sensitive receivers" that are at risk of being impacted by air pollution were identified. These include several institutions such as residences, hotels, hospitals, offices, factories and educational institutions. The study areas included air sensitive receivers located at a minimum distance of 500 meters from the boundaries of the construction sites. The air quality standards were those stated by the "Hong Kong Air Quality Objectives".
The tool used to assess impacts of the construction phase was the "Fugitive Dust Model". This model permits to compute air dispersion as well as dust particle size distribution.
For the operational phase, an air quality prediction model, the "Pollutants in the Atmosphere and the Transport over Hong Kong" model, was used to evaluate nitrogen oxides emissions for the following years:
- 2015: HKLR commissioning year and Phase 1 commissioning of the HKBCF
- 2016: Phase 2 commissioning of the HKBCF
- 2021: Intermediate year between 2016 and 2031
- 2031: 15 years after Phase 2 commissioning of the HKBCF
Assessment Results
After the assessment of dust emissions from the construction phase, results showed that the total suspended particulate matter hourly concentrations exceeded the acceptable levels for several air sensitive receivers. Thus, several mitigation measures were demanded so that dust levels would comply with the standards. One method consists of watering dusty construction material and wheel-washing of vehicles on a basis of 8 times a day.
According to the results of the operational phase assessment, nitrogen oxides concentrations in the atmosphere would not exceed the standards. Therefore no residual impacts on air quality due to the operation of the infrastructure were expected.
This photo shows wheel-washing of a vehicle.
Noise Impacts
Acceptable noise levels for private and public institutions, which were established by the Hong Kong Environmental Protection Department, served as standards for the assessment. Most of the acceptable noise levels during daytime ranged from 65 to 75 decibels, which is equivalent to average street noise.
Assessment Method
A program for noise calculations was used to model construction noise. The ''RoadNoise2000" program was also used for traffic noise assessment.
Assessment Results
According to the evaluation, construction noise would have exceeded the daytime noise criteria. To comply with the standards, mitigation measures were proposed:
On the other hand, the model for road traffic noise showed that noise levels would comply with the criteria for all noise sensitive receivers studied. It was also concluded that no cumulative noise impacts would arise from the operation of the infrastructures.
Movable noise barriers are shown
in this photo.
Assessment Method
A program for noise calculations was used to model construction noise. The ''RoadNoise2000" program was also used for traffic noise assessment.
Assessment Results
According to the evaluation, construction noise would have exceeded the daytime noise criteria. To comply with the standards, mitigation measures were proposed:
- Movable noise barriers near plants
- Mobile plants locations far from noise receivers
- Silencers and mufflers on construction equipment
On the other hand, the model for road traffic noise showed that noise levels would comply with the criteria for all noise sensitive receivers studied. It was also concluded that no cumulative noise impacts would arise from the operation of the infrastructures.
Movable noise barriers are shown
in this photo.
Water Quality
The project entails several processes that may give rise to a number of water quality issues during both the construction and the operational phases. Below are some of these issues.
Construction Phase
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Operational Phase
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Assessment Methods
Water sensitive receivers, which include areas of ecological value or of public use, were identified. A computer program was used to model tidal flows according to construction and operational procedures.
For the construction phase, model simulations were carried out for the following years:
The following water quality parameters were evaluated for the operational phase:
The obtained values were converted into monthly averages for surface, mid-layer and bottom layers in the water.
Assessment Results
Mitigation measures were required for the physical and chemical changes to water quality to reach acceptable levels. Below are the suggested measures.
Water sensitive receivers, which include areas of ecological value or of public use, were identified. A computer program was used to model tidal flows according to construction and operational procedures.
For the construction phase, model simulations were carried out for the following years:
- 2011: Beginning of construction. Potential sediment release from dredging would be at its maximum.
- 2012: Construction would have the potential to alter tidal currents.
- 2013: Construction would almost be completed. Sediment releases into the water would be reduced.
- 2026: Completed bridges construction and reclamation work. Long term operational impacts can be evaluated.
The following water quality parameters were evaluated for the operational phase:
- Water temperature
- Salinity
- Dissolved oxygen
- Suspended solids
- Total inorganic nitrogen
- Biological oxygen demand
- Ammonia
- E. coli
- Sedimentation
The obtained values were converted into monthly averages for surface, mid-layer and bottom layers in the water.
Assessment Results
Mitigation measures were required for the physical and chemical changes to water quality to reach acceptable levels. Below are the suggested measures.
Construction Phase
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Operational Phase
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Monitoring and Follow-up
Air Quality
The equipment that will be used for air quality monitoring at dust sensitive receivers locations consists of air samplers. The sampling frequancy will be of at least once in every 6 days for for 24-hour total suspended particles monitoring. Laboratory analyses of the samples will follow. If dust concentrations exceed the standards for air quality, further monitoring and implementation of mitigation measures will be required.
Noise Impact
Sound level meters are the equipments to be used for noise monitoring. Institutions that are closest to the sites of important noise will serve as study areas. Mitigation measures are to be applied in case of non compliance with the acceptable noise levels.
Water Quality
Several equipments, which are listed below, must be used to evaluate water quality parameters.
The equipment that will be used for air quality monitoring at dust sensitive receivers locations consists of air samplers. The sampling frequancy will be of at least once in every 6 days for for 24-hour total suspended particles monitoring. Laboratory analyses of the samples will follow. If dust concentrations exceed the standards for air quality, further monitoring and implementation of mitigation measures will be required.
Noise Impact
Sound level meters are the equipments to be used for noise monitoring. Institutions that are closest to the sites of important noise will serve as study areas. Mitigation measures are to be applied in case of non compliance with the acceptable noise levels.
Water Quality
Several equipments, which are listed below, must be used to evaluate water quality parameters.
- Dissolved oxygen and temperature measuring instrument
- Turbidity measurement instrument
- Water sampler
- Water depth detector
- Salinometer
- pH measuring equipment
Our Critique
Positives
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Negatives
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