13 Summary of Environmental Outcomes

13.1.1 Based on the tentative construction programme, the decommissioning of the former Kai Tak Airport other than the North Apron would be commenced in early 2008 and completed in late 2009. Based on the latest available information, no planned sensitive receivers are anticipated at the North Apron, South Apron, and the Runway area of the former Kai Tak Airport before completion of the proposed decommissioning works in 2009. The major environmentally sensitive areas within the study area include the existing sensitive receivers at the surrounding existing urban districts. With the implementation of the proposed control and mitigation measures, the air, noise and water quality sensitive receivers within the study area would be protected from adverse environmental impacts arising from the proposed decommissioning works.

13.1.2 A summary of the key environmental outcomes arising from the EIA study and environmental benefits of the environmental protection measures recommended are presented in Table 13.1 below.

Table 13.1 Summary of Key Environmental Outcomes/ Benefits

Issue	Environmental Outcomes/Benefits
The Project	Requirements: · To demolish some of the remaining existing structures / building and remove abandoned facilities of the former Kai Tak Airport within the Project boundary including the off-shore disused fuel dolphin and the associated connecting abandoned fuel pipelines; · To identify and clean up contaminated areas associated with the previous airport operation within the Project boundary identified during the EIA; and · To implement appropriate mitigation measures to ensure site would be safe and free of hazards for the planned future use. Benefits: · The Project will make available the remaining former Kai Tak Airport site for future residential, commercial, tourism and leisure developments to meet the long term development, economic and social needs of Hong Kong. The Project will be implemented properly to ensure that the future sensitive receivers within the Kai Tak Development and the existing sensitive receivers at the surrounding urban districts would not be subject to adverse environmental impacts during and after completion of the decommissioning works. Potential consequences without the Project: · Without demolishing remaining existing structures/building and remove abandoned facilities of the former Kai Tak Airport, the development opportunity of Kai Tak Development will be reduced; and · Without identify and clean up contaminated areas associated within the previous airport operation, it would not be safe and free of hazards for the construction workers and future land users.

Consideration of Alternatives	(i) Decommissioning of Dolphin Structure and its Associated Disused Fuel Pipelines · In regard to the decommissioning of the disused fuel dolphin structures and its associated pipelines, two options have been proposed: Option 1 – Complete removal of the fuel dolphin structure and the connecting fuel pipelines Option 2 – Demolish the fuel dolphin structure down to 1m below existing seabed and leave the connecting fuel pipelines in-situ; the disused fuel dolphin structure would be demolished by cutting off the piles to 1m below existing seabed and the sediment around the piles would be pushed aside to facilitate the pile cutting and no dredging would be required for the demolition works. · The fuel dolphin structure had ceased in use since 1998 and there appeared at present no other beneficial use of the dolphin structure. Option 2 is a preferred approach over Option 1 environmental ground as it will not involve any dredging and will minimise the disturbance to the potentially contaminated sediment in the vicinity of the fuel dolphin and the fuel pipelines. · In summary, it is proposed to demolish the fuel dolphin down to 1m below existing seabed. The disused fuel pipelines will be left in place and, if necessary, grouted with concrete. This approach will eliminate the need for any major dredging, filling, and sediment disposal activities and hence reduce the environmental impacts associated with the decommissioning works. (ii) Decontamination of Contaminated Soil · Remediation is required to clean up contaminated areas associated with the previous airport operations to ensure the site would be safe and free of hazards for the planned future uses. Possible remediation technologies for metals, TPH, VOCs (elthylbenzene and xylenes) and SVOC (benzo(a)pyrene) contaminated soil have been proposed: · Metals contaminated soil: Option 1: Soil washing Option 2: Electrokinetic Separation Option 3: Solidification / stabilization Among these remediation technologies, solidification / stabilization is considered as the most practical and cost-effective method to treat the metals contaminated soil on site. The solid monolithic block adopted in this solidification / stabilization technique is extremely resistant to the leaching of inorganic contaminants. Additives can be added to assist in chemically binding the contaminants in a matrix that typically shows unconfined compressive strengths similar to a soil-cement mix. Solidification / stabilization has been used on certain contaminated sites in Hong Kong and as a successful treatment method for inorganic contaminated soil, e.g. decontamination works at the Cheoy Lee Shipyard at Penny’s Bay, reclamation works at North Tsing Yi Shipyard site and few isolated sites identified in the Deep Bay Link project. Therefore, on-site solidification / stabilization technique is proposed for remediation of the metals contaminated soil identified in the south apron area and the ex-GFS apron area. · TPH / VOCs / SVOC contaminated soil: Option 1: Biopiling Option 2: Soil venting Option 3: Land Farming Option 4: Landfill Disposal Among these remediation technologies, biopiling is considered as the most practical and cost-effective method to treat TPH / VOCs / SVOC contaminated soil on site. Since landfill space is very limited and valuable in Hong Kong, landfill disposal shall be considered as the last resort for TPH / VOCs / SVOC contaminated soil when other remediation methods are not applicable. Soil venting is not applicable to the contamination which is localized and discrete identified in the north apron while land farming requires longer treatment time and may induce possible dust and vapour emission to the surrounding sensitive receivers. Therefore, on-site biopiling is considered as remediation method for soil contaminated by TPH / VOCs / SVOC identified in the south apron area, the narrow strip of the north apron near the Kai Tak Tunnel and the ex-GFS apron area since this remediation technology is an effective technology to treat TPH / VOCs / SVOC contaminated soil with several successful local cases such as Cheoy Lee Shipyard and the North Apron of Kai Tak Airport. · TPH and metals contaminated soil is proposed to first be treated by biopiling and then followed by solidification / stabilization. (iii) Decontamination of Contaminated Groundwater · In light of the presence of the floating free product, it is proposed that where free product is detected at the groundwater surface at excavated areas, free product recovery should be performed to remove the free product. Possible free product recovery technologies have been proposed: Option 1: Skimming System Option 2: Free Product Recovery with Water Table Depression Option 3: Vapor Extraction / Groundwater Extraction Option 4: Dual - Phase Recovery Among these free product recovery technologies, skimming system is considered as the most practical and cost-effective method for recovery of free product at the ex-GFS apron area because the quantity of free product would be small (about 6.8m³) and (2) skimming system has been adopted in several successful local land contamination studies such as Cheoy Lee Shipyard and North Apron of the former Kai Tak Airport.
Land Contamination	· Construction workers are considered as the most likely group to be exposed to the contaminated materials during excavation and remediation works via ingestion, dermal contact and inhalation. · Site investigations conducted for each sub-area within the Study Area [i.e. the south apron area, the runway area and the narrow strip of the north apron, and the ex-GFS apron area] identified that some areas in the south apron area, the ex-GFS apron area and the narrow strip of the north apron near the Kai Tak Tunnel were contaminated with metals, TPH, VOCs (ethylbenzene, xylenes) and SVOC (benzo(a)pyrene). No contamination was found in the former airport runway. · Results of the groundwater risk assessment indicate that concentration of the chemical-of-concerns (COCs) in the groundwater, including metals (including barium, cadmium, copper, molybdenum, lead, tin, zinc, thallium, vanadium, antimony, chromium, cobalt and nickel), VOCs (benzene, ethylbenzene, xylenes) and SVOC (benzo(a)pyrene, fenanthrene and naphthalene), do not exceed risk-based criteria for remediation except TPH. In accordance with on-site measurement, floating free products were observed in the ex-GFS apron area. In order to reduce the safety and health risk, it is therefore proposed that free product shall be recovered by skimming and collected by a licensed chemical waste collector for proper disposal. · Biopiling is proposed to treat TPH / VOCs / SVOC contaminated soil while solidification / stabilization is suggested to treat the soil contaminated with metals. For soil contaminated with metals and TPH, it is suggested to treat the contaminated soil by biopiling first and followed by solidification / stabilization. It is recommended that the soil treated by biopiling should be reused on-site as fill material as far as practicable while the soil treated by cement solidification / stabilization, the solidified / stabilized soil should be backfilled on-site and then covered by 1m of clean fill. · Contamination assessment report / remediation action plan (CAR/RAP) for each sub-area within the Study Area have been prepared and attached in this EIA report to summarise the findings of site investigation and outlined the remediation works for the identified contaminated areas. · No adverse residual environmental impact in respect of land contamination is anticipated upon completion of the recommended remediation actions.
Waste Management	· Main waste: C&D material from demolition of the remaining structures with a total volume of approx. 4100 m³. · Other wastes: chemical waste from the maintenance of construction plant and equipment and from the decontamination process; and general refuse from the workforce.
Water Quality	· Water quality impacts from the land-based decontamination works, associated with leachate and contaminated runoff, can be controlled to acceptable levels by implementing the recommended mitigation measures. All the effluents and runoff generated from the works areas shall be treated and their quality be monitored before discharged. No unacceptable water quality impacts would be expected from the land-based decommissioning activities. · The proposed method for decommissioning of the disused fuel dolphin would not involve any dredging and in view that the works area would be small, any potential marine water quality impact arising from the decommissioning works would be minor and localized and no unacceptable marine water quality impact would be expected. · Site inspections should be undertaken routinely to inspect the works areas in order to ensure the recommended mitigation measures are properly implemented.
Air Quality	· No adverse construction dust arising from the Project and dust emission from other concurrent activities would not pose cumulative dust impact to the ASRs in the vicinity of the Project boundary. Requirements of the Air Pollution Control (Construction Dust) Regulation and good site practices shall be adhered to during the construction period. · Predicted results indicated that negligible soil gas emission from the decontamination works would be expected at the ASRs in the vicinity of the work site. With the implementation of proposed mitigation measures at the works sites of contaminated pits during excavation, transportation & unloading of excavated contaminated soil, biopiling and solidification process, and installation and proper operation of carbon absorber for biopile facilities, the air quality impact from decommissioning other than dust impact is anticipated to be acceptable. · Very minor odour impact (petroleum/kerosene smell) is anticipated during soil excavation as the excavation area would be limited and clean material would backfill immediately after excavation, and the excavated soils would be covered with impermeable liner to minimise odour emission. · No adverse health risk from dust emission attached with heavy metals would be anticipated in view of small amount of soils contaminated by heavy metals and implementation of mitigation measures during excavation, transportation and unloading and decontamination works.
Noise	· Predicted noise levels at nearest NSRs would comply with EIAO-TM criteria. No adverse construction noise impact arising from the Project would be expected at the NSRs in the vicinity of the work sites. · Good site practices are proposed to be implemented.
Cultural Heritage	· The built heritage resources found in Study Area including the three wind poles, the airport pier, Fire Station B and its adjacent pier, Fire Station C, runway and seawall. · The assessment concluded that all the above heritage resources are of low cultural heritage significance. None of the heritage resources examined will be affected by the Project, no further mitigation will be required.
Marine Ecology	· Direct impacts to the marine ecological resources would include permanent loss of small area of subtidal hard substratum of the fuel dolphin structure. No direct loss of important marine resources such as coral would be resulted and such impact is considered as very minor in nature. · Potential direct disturbance on benthic habitats and associated marine life would be resulted from the proposed marine works. Considering that the benthic habitats within the assessment area are of very low ecological value, no adverse impact is expected. · Indirect impacts on the marine ecology would be associated with changes of water quality due to seabed disturbance arising from proposed marine works and site run-off from land-based construction site. As water quality assessment suggested that change of water quality within the assessment area would be minor and acceptable during the construction phase, indirect impact on marine life including coral colonies recorded in the assessment area is expected to be minor and minimal. · During the construction works, increased marine traffic and noise generated from construction plant could cause disturbance impacts to the associated wildlife including the waterbirds of conservation interest. It is expected that displacement of waterbirds to the nearby waters for roosting and feeding area may occur temporarily but adverse impact is not anticipated.