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LCQ13: Handling of fuel ashes

     Following is a question by the Hon Chan Kin Por and a written reply by the Secretary for the Environment, Mr Edward Yau, at the Legislative Council meeting today (February 16):


     It has been reported that more than 20 substances (including heavy metals and chemical compounds such as cadmium, chromium, arsenic, mercury and lead, etc.) that are harmful to the environment and human health have been found by a green group in the samples of pulverized fuel ashes gathered from 14 ash sites of power stations on the Mainland.  Some environmentalists have pointed out that at present, coal dominates more than half (about 54%) of the fuel mix for power generation in Hong Kong, and the impact of the fuel ashes generated each year on the environment and public health has all along been of grave concern.  In this connection, will the Government inform this Council:

(a) whether it knows the amount of fuel ashes generated in Hong Kong in each of the past five years and the way in which they had been handled;

(b) whether it knows the handling process adopted by power stations in Hong Kong for delivering fuel ashes to ash lagoons; how they ensure that the fuel ashes exposed to the air do not contain heavy metals and chemical compounds so as to avoid affecting the surrounding environment; and of the measures to prevent diffusion and permeation;

(c) whether the Government had conducted any test in the past five years on the heavy metal and chemical compound contained in treated fuel ashes generated by power stations; if it had, of the outcome; if not, the reasons for that; whether it knows if fuel ashes disposed of at collection sites contain heavy metal and chemical compounds; if so, of their contents, and whether such contents have any impact on the surrounding environment and living creatures, including the public and migratory birds, and how the Government ensures that the ashes do not affect the environment and public health; and

(d) whether it knows the present environment of the sites used for the disposal of fuel ashes and the situation of their surrounding areas; of the criteria based on which the Government assesses if those sites meet the environmental safety standards; whether there are any indications that the sites will be full in the next few years; if so, how the Government will deal with the matter?



(a) In the past five years, the annual average amount of coal ash produced from power generation by CLP Power Hong Kong Ltd. (CLP) and Hongkong Electric Co. Ltd. (HEC) in Hong Kong was around 240 ,000 and 320 ,000 tonnes respectively, the majority of which had been recycled and sold for the production of cement, concrete and other construction materials.

(b) For coal ash which has not been sold and requires storage, the power companies use water as the medium for transporting the ash through completely enclosed pipelines to the ash lagoons for storage.  There will not be any air-borne dust in the transportation process.  The ash lagoons have also adopted measures for preventing fugitive dust, e.g. putting in place dust suppression system or keeping the stored ash below the lagoon water level.  The lagoons are also protected with liner to prevent the seepage of coal ash and water.

     HEC's ash lagoon is only used for fallback temporary ash storage in the unlikely event that regular ash off-take is interrupted.  In the past five years, there was no need for HEC to transfer any ash to the lagoon.

(c) and (d) The principle constituents of coal ash are silica, alumina, iron and calcium, etc.  In general, coal, like soil, rocks and other natural materials, contains a small amount of heavy metal.  Coal ash resulting from coal-fired generation has a very low level of heavy metal.

     The Environmental Impact Assessment (EIA) Ordinance specifies that "a waste disposal facility for pulverized fuel ash, furnace bottom ash or gypsum" is a designated project.  All newly proposed designated projects have to go through the statutory EIA process to demonstrate that their construction and operation at the selected sites can comply with the criteria specified in the Technical Memorandum on EIA Process before an environmental permit can be issued.  Operation of these facilities is also regulated by other relevant pollution control ordinances.

     CLP's ash lagoon is located at Tsang Tsui which is 7 km away from the power station.  Dust and underground water monitoring stations have been set up in the periphery of the ash lagoon to monitor the environmental impact of the ash lagoon in accordance with the requirements of the Environmental Protection Department (EPD).  Monitoring data have to be submitted to EPD regularly.  According to the data for the past three years, the 24-hour average dust concentrations in the area were comparable to other air monitoring stations in Hong Kong and complied with the relevant air quality objective.  Findings from periodic underground water monitoring do not indicate any adverse impact on the underground water quality in the vicinity.  For HEC, its ash lagoon is located inside the Lamma Power Station.  HEC has set up equipment to monitor the dust concentration in the vicinity of the power station and the data showed that the relevant air quality objective was met.  

     CLP believes that the existing capacity of the ash lagoon is adequate for the coming few years.  HEC does not see any need for additional storage facilities either, in view of the demand for coal ash by local and Mainland construction industries.

Ends/Wednesday, February 16, 2011
Issued at HKT 12:30


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