3                                            Environmental Impacts

The nature and extent of the environmental impacts associated with the construction and operation phases of the Project are summarised below. 

3.1                                      Land Contamination

For installation of the FGD plants, two above ground oil storage tanks (No. 4 and No. 5 Light Oil Tanks) with associated pipelines and one oil separation sump are to be demolished to provide space for installation of the FGD plants.   Contamination Assessment Plan (CAP) has been prepared and approved by the EPD in November 2005 and site investigation (SI) was conducted in the area adjacent to the tanks and oil separation sump.  The SI results indicated that total petroleum hydrocarbon (TPH) was detected at one soil samples and five groundwater samples exceeding Dutch B guideline for mineral oil.  Results of the SI and recommendations have been reported in the Contamination Assessment Report (CAR) and the Remedial Action Plan (RAP) (see Annex of the EIA Report). Therefore, remedial measures and procedure for TPH contamination are recommended in the RAP. 

With the implementation of the remedial measures in RAP, no land contamination would be anticipated.

3.2                                      Air Quality

Dust nuisance is the key concern during the construction of the Project.  Demolition of the existing Nos 4 and 5 Light Oil tanks with each of 250m3 storage capacity, civil works of the retrofitting of FGD Plants to two existing 350MW coal-fired Units L4 & L5 are the major construction works of the Project.  Due to small scale of the Project and with the implementation of the recommended dust suppression measures stated in the Air Pollution Control (Construction Dust) Regulation, no dust impact is anticipated.  In addition, only limited number of diesel-driven equipment will be operated on site, therefore, impact from construction equipment is not expected. 

For the operational air quality assessment, the re-assessment of the previous wind tunnel modelling data has confirmed that the FGD retrofit project at units L4 and L5 of the Lamma Power Station will lead to significant reductions of the worst-case hourly SO2 concentrations for most ASRs throughout the area studied. 

Other environmental benefit of the FGD retrofit includes the reduction of the particulate matter (PM) emissions resulted from the wet scrubbing process of the FGD plant. 

The NOx emissions will not be reduced nor increased by the project, however changing of the stack exhaust parameters may result in a re-distribution of NOx in the vicinity of the power station. The cumulative concentrations of NO2 after the retrofit have been estimated and their AQO compliance demonstrated for at all ASR locations.

Based on the impact assessment, the current monitoring programme for the Lamma Power Station can cover the Project and no additional EM&A measures are required.

3.3                                      Water Quality

Construction runoff and sewage effluents generated from the workforce are the potential sources of water quality impacts during construction.  Assessment results indicate that no unacceptable water quality impacts will arise from the construction activities provided that the recommended mitigation measures are implemented.

Potential source of impacts to water quality from the operation of the FGD plants are as a result of filtrate generated from the dewatering of gypsum slurry.  Since the existing WWTP has spare capacity to cater for the additional wastewater produced from the proposed retrofit project, it is expected that effluent from the WWTP to the Ash Lagoon will meet the requirements in the WPCO licence for the Ash Lagoon Decantrate Tower.  Thus, no water quality impact arising from the operation of the FGD plants are anticipated.

Based on the impact assessment, the current monitoring programme for the Lamma Power Station can cover the Project and no additional EM&A measures are required.

3.4                                      Waste Management

The key potential impacts during the construction phase are related to management of demolition materials, excavated materials and construction waste.  With the implementation of the mitigation measures recommended, the potential environmental impacts arising from storage, handling, collection, transport and disposal of wastes should be able to meet the criteria specified in the EIAO-TM.  Hence, no unacceptable waste management impact is anticipated.

All the additional gypsum (about 46,000 tonnes per year) and sludge (about 1,200 tonnes per year) will be generated and reused in Hong Kong and/or in Mainland China and no disposal is required.  With the implementation of the recommended mitigation measures, the potential environmental impacts associated with the storage, handling, collection, transport and disposal of a small quantity of industrial and chemical wastes arising from the operation of the two new FGD units will meet the criteria specified in the EIAO-TM and no unacceptable waste management impact is anticipated.

3.5                                      Noise

The proposed Project is in small scale.  Additionally, in the view that the residential developments are shielded from construction noise to varying degrees by the intervening hill (Kam Lo Hom) and the existing plants, and considerable separation distance between the NSR and the Project, the noise generated during the construction stage is not expected to be a concern.  .  However, in order to ensure that the construction noise levels at the NSRs controlled within the relevant criteria, good site practice and noise management is recommended during the construction phase. 

Based on a worst-case scenario, the operational noise levels due to additional equipment will comply with the noise criterion and will have insignificant contribution to the cumulative operational noise of the Lamma Power Station.  Therefore, the plant noise associated with the retrofit plant is not expected to give rise to unacceptable environmental impacts.    

In addition, most of the noise sources associated with the retrofit project will be housed within individual acoustic enclosure to minimise the noise impact to the environment. 

In view of the anticipated insignificant noise impact in both construction and operational phases, additional noise monitoring work for this Project is considered not necessary. 

3.6                                      Project Visibility

 The proposed retrofit works will not have any negative impact on the surrounding landscape, and will have a very low visibility for the following reasons:

·       The location for the proposed retrofit works is within a large existing industrial facility;

·       There will be no impacts on the surrounding landscape area;

·       The new infrastructure will be finished to complement the existing industrial surroundings;

·       The relatively small scale of the retrofit works within the existing facility means that the works will have a low visibility.