Environmental Impact Assessment Ordinance (Cap. 499)
(ACE-EIA Paper 4/2002)
For advice
Environmental Impact Assessment
Yau Tong Bay Development - Reclamation of Yau Tong Bay
Purpose
This paper presents the key findings and recommendations of the Environmental Impact Assessment (EIA) Report for the Yau Tong Bay (YTB) Development - Reclamation of Yau Tong Bay (hereafter known as the Project), submitted under section 6(2) of the Environmental Impact Assessment Ordinance (EIAO). The Main Wealth Development Limited and their consultants will make a presentation. Comments from the public and the ACE will be taken into account by the Director of Environmental Protection when he makes the decision on the approval of the EIA report under the EIAO.
Advice Sought
2. Members' views are sought on the findings and recommendations of the EIA report.
Need for the Project
3. The Project is planned to proceed by reclaiming land in YTB and resuming the existing marine lots to develop the future Comprehensive Development Area (CDA). Part of the site, of about 17.4ha in size, has been zoned CDA in 1998 by the Town Planning Board Metro Planning Committee, under the Cha Kwo Ling, Yau Tong, Lei Yue Mun Outline Zoning Plan.
Description of the Project
4. The existing YTB is characterized by the YTB marine lots within the Yau Tong bay. Currently, a wide variety of activities are undertaken at the YTB marine lots to include shipyard, timber yard, sawmill, material storage, concrete batching and industrial building (see Figure 1). The Study identifies the following designated projects under Schedule 2 of the EIA Ordinance (Cap. 499):
- reclamation works at YTB, under schedule 2 section C.1 of the EIAO; and
- decommissioning of shipbuilding and repairing facilities at the marine lots, under schedule 2 Part II of the EIAO.
5. The extent of the YTB reclamation would be dictated by the ultimate alignment adopted for the proposed Western Coast Road (WCR). If the WCR should run along the existing coastline to link Tseung Kwan O (TKO) to South East Kowloon (SEK), the Study has assumed a "Full Reclamation" scenario with the viaduct foundation of the WCR constructed on land. This will result in a total project area of about 28.5ha of which 18ha will be reclaimed land. If the WCR should run link TKO to SEK via an inland tunnel, the Study has assumed a "Minimized Reclamation" scenario that will result in a total area of about 21.5ha, with the reclaimed area reduced to about 12ha. To avoid affecting the existing fresh water main and a twin cross harbour submarine gas pipelines, a removable concrete decking supported on bored piles will be constructed above these pipelines. The reclamation is scheduled to start in early 2004, and for completion in 2007.
6. As the proponent applied for separate study briefs at a time lapse of about one year in between, the two EIAs, one to cover the YTB reclamation and the other on the engineering feasibility study for the YTB comprehensive development, have been carried out separately. The two EIAs are submitted together such that the overall cumulative environmental impacts on the various phases of developments can be addressed and presented in a holistic manner.
Previous Submission under the EIAO
7. The applicant submitted an EIA report for the project on 25 July 2000 under the EIAO. The Director of Environmental Protection (DEP) replied on 20 September 2000 that the report did not meet the requirements in the EIA Study Brief and the Technical Memorandum on EIA Process. The reasons are deposited on the EIAO Register and the EIAO website. A copy is attached in Appendix A for easy reference.
8. Since then, considerable revisions have been made and the EIA report was resubmitted under section 6 of the EIAO.
Specific Environmental Aspects to Highlight
9. The major environmental issues identified for the project are: water quality impact, contaminated sediment treatment, land contamination impact and biogas hazards.
Water Quality Impact
10. No adverse water quality impacts are anticipated and Water Quality Objectives will be met by the adoption of the following mitigation measures:
- Geotextile be placed over the seabed;
- Closed grab dredgers with silt curtain be used for the dredging and filling of seawall foundation;
- A silt curtain be placed across the seawall opening during the Phases 1 & 2 reclamations using bottom dumping;
- Double layers of silt screen be installed at the salt water intakes; and
- The filling rates of Phases 1 and 2 reclamations are limited to 10,000m3/day and 6,000m3/day respectively.
11. Upon completion of the YTB reclamation, the surface flow pattern at the boundary of the reclamation is expected to be close to the original prior to reclamation. The change in annual average discharge across the Victoria Harbour for the "Full Reclamation" scenario will be reduced by less than 0.5%, and the corresponding discharge caused by the "Minimized Reclamation" is expected to be even less. Modeling results indicated that water quality parameters would not be adversely affected by the presence of the reclaimed areas in YTB. Tidal flushing will prevent the accumulation of pollutants under the proposed concrete decking, and the water quality at the saltwater intakes is expected to comply with the Water Supplies Department's tolerable limits.
Contaminated Sediment Treatment
12. Seabed dredging for the construction of seawall foundation and box culvert extension would generate an estimated total dredged volume of 175,150m3 of marine mud for the "Full Reclamation" scenario, of which 82,800m3 are classified as contaminated mud. Under the "Minimized Reclamation" scenario, the total dredged volume is estimated to be 112,170m3, with 53,270m3 classified as contaminated mud. The contaminated mud will be disposed at the East Sha Chau Contaminated Mud Disposal Pits or other designated dumping grounds to be imposed under the Dumping at Sea Ordinance and in accordance with the requirements of the relevant Works Bureau Technical Circulars. Those contaminated mud that failed to pass the biological test will be sealed in geosynthetic containers before disposal.
Land Contamination Impact
13. The total volume of contaminated soil within the existing marine lots is about 21,260m3. The soil contaminated with mercury is about 1,230m3, and this will be disposed off at landfill. The volume of soil with Total Volume Hydrocarbon (TPH) level exceeding the Dutch B level is about 16,730m3. This is to be treated by the biopile method, where naturally occurring organisms will consume petroleum hydrocarbons as a food source and break them down into harmless compounds (such as carbon dioxide and water). The volume of soil contaminated with metals (mainly lead and copper) is about 2,100m3. This is to be treated by solidification, where cement, fly ash and sand are blended with the contaminated soil to set into solid monolithic blocks. For the 1,200m3 of soil contaminated with both TPH and metal, it will be treated by biopiling and then solidification. Apart from the mercury contaminated soil which will be disposed at landfill, samples of 1 number per 10m3 will be taken from all other decontaminated soil to ensure compliance with acceptance criteria before backfilled on-site as clean soil.
Biogas Hazards
14. Methane gas could be generated from the organically enriched material that is planned to be left in-situ beneath the proposed YTB reclamation to reduce the need for land or marine disposal. The gas generation rate could be high in the beginning, and is expected to follow an exponential decrease over the course of time. Gas protection measures will be incorporated for both the ground level and underground structures at the development to prevent the ingress and/or accumulation of any methane gas emissions to potentially dangerous concentrations. In addition, there will be gas monitoring in the immediate post-reclamation period and prior to the commencement of construction works on the reclamation to measure methane concentrations. The methane gas generation potential is not expected to pose a development constraint to the YTB.
Environmental Monitoring & Audit (EM&A)
15. A framework for EM&A has been put forward in the EM&A manual submitted in the EIA. The EM&A requirements will be enforced as Environmental Permit conditions.
Comments received so far from the public during the Public Inspection Period
16. The applicant has made the EIA report, EM&A manual and Executive Summary available for the public to comment under the EIAO on 1 February 2002. Members will be briefed about any comments received from the public at the meeting.
Environmental Assessment and Noise Division
Environmental Protection Department
February 2002
