By: Martin Lee, Jey Hwan Lee, Wilson Leung. Background Former HKIA, replaced in 1998 ▫World’s...
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Transcript of By: Martin Lee, Jey Hwan Lee, Wilson Leung. Background Former HKIA, replaced in 1998 ▫World’s...
Background• Former HKIA, replaced
in 1998▫ World’s busiest in 1997▫ Overcrowded
• World famous difficult landings into runway 13▫ North end: 6 stories high
buildings▫ Often used due to
prevailing wind directions▫ Visual approach required
After retiring…• Land used for
development▫ Sports Stadium▫ Cruise Terminal▫ Hotel▫ Etc…
From Maunsell AECOM Asia Ltd
• Contaminated land detected:▫ Ex-Government Flying
Services (ex-GFS)▫ South of North Apron▫ South Apron
Causes & Hazards• Causes:
▫ Underground fuel hydrant leakages▫ Oil Companies Tank Farm leakages▫ Workers pouring fuel over pavement
• Contaminants:▫ Total Petroleum Hydrocarbon (TPH)
Toluenes and Xylenes (BTEX) Methane (in explosive concentrations)
▫ Heavy Metals Polyaromatic Hydrocarbons Polychlorinated Biphenyls
• Hazards:▫ No explosive hazard as concrete layer seals underground
contaminants from open air▫ Toluene causes Nausea▫ Xylenes cause headaches, lung issues, muscle co-ordination
problems
Remediation Options
•Bioremediation•Soil Vapour Extraction•Air Sparging•Dual-phase extraction•Low-Temp. Thermal Desorption•Chemical Oxidation•Bio-pile•Capping•Cement stabilisation/solidification•Landfarming
Remediation Adopted
1. Soil Vapour Extraction (SVE)▫ Air Sparging
2. Bio-pile3. Bioremediation
• Mitigating Environmental Effects:1. Vapour Emission Treatment Systems2. Oil Interceptors3. Noise Silencers
Soil Vapour Extraction/Air Sparging - Method
• Method1. Drill Wells into soil
above W.T.2. Apply Vacuum
Pressure3. Underground vapour
pulled out4. Air treatment system
collects vapours5. Separates
contaminants from air6. Contaminants
disposed safely
Soil Vapour Extraction/Air Sparging - Application• Pros:
▫ Simple to install & maintain
▫ Safe and natural process▫ Minimal disturbances to
soil profile
• Cons:▫ Empirical Design, no
theoretical equations▫ Doesn’t deal with soils
under W.T.▫ Cannot deal with low
conc.
• In-situ• Removes subsurface
contaminants, such as Volatile Organic Compounds (VOC)
Bio-pile - Method• Method
1. Identify soil characteristics
2. Excavate soil3. Mix excavated soil with
soil amendments4. Heap contaminated soils
into piles5. Enclose the
contaminated soil6. Contaminants removed
through controlled aerobic microbial activity
Bio-pile - Application• Pros:
▫ Simple to design and implement
▫ Short treatment times (6 months – 2 years)
▫ Relatively cheap (30-90 USD/ton of contaminated soil)
▫ Closed system (vapor emissions controlled)
• Cons:▫ Require a large land area for
treatment▫ Not effective for high
constituent concentrations ▫ Volatile constituent tend to
evaporate rather than biodegrade during treatment
• Ex-situ• Used to reduce concentrations
of petroleum constituent products through biodegradation
Bioremediation - Method1. Wells injected to
groundwater level2. Calcium Nitrate solution
is pumped into soil through wells
3. Oxygen and water is occasionally supplied to wells
4. Solution is spread throughout contaminated areas
5. Extraction wells collects groundwater for further water treatment.
Bioremediation - Application• In-situ• Injection of calcium nitrate to promote growth of
NRSOB• Eliminates odour from degradation of organic
compounds caused by SRB• Pros:
▫ Natural process▫ Easily conducted on-site▫ Efficient, Satisfactory result, short time ▫ Little or acceptable environmental impact▫ Low cost
• Cons:▫ Requires constant monitoring to ensure effectiveness▫ Takes a little longer than some techniques▫ Little knowledge on its long term effect on areas of
multiple contamination