History of the Site
Dalin Refinery Plant is located at Kaohsiung’s Xiaogang District, in the Kaohsiung waterfront industrial area, on the south side of the Kaohsiung Second Harbor. In addition of being an important supply station and transfer center for oil, it is also an important town for oil storage and refining in Taiwan.
The polluted area in zone F of Dalin Refinery Plant is about 23 hectares. Since 2011~2013, free-oil leakages have been identified via CPI (Corrugated Plate Interceptor) of wear welding point. The Site was reviewed and declared as a pollution remediation site in 2016 by EPA. The contamination components were naphtha, motor fuel, BTX（Benzene, Toluene, Xlyene) and by-products.
Pollution in figures
The contaminated soil is about 670 tons, covering an area of about 12,400 square meters, and the depth of contamination ranges from 2 to 8 meters.
- Benzene: 1,420 mg/kg
- Toluene: 6,860 mg/kg
- Ethylbenzene: 931 mg/kg
- Xylenes: 4,710 mg/kg
- Total petroleum hydrocarbons (TPH): 40,300 mg/kg
The maximum contamination levels measured in the groundwater (area of approximately 54,800 square metres) were as follows:
- Benzene: 132 mg/L
- Toluene: 125 mg/L
- Ethylbenzene: 8.75 mg/L
- Naphthalene: 1.46 mg/L
- Total petroleum hydrocarbons (TPH): 973 mg/L
Apollo Technology Added Value
The site is polluted with light carbon chains (approx. C6-C11) and is therefore suitable for in situ remediation techniques such as dual-phase extraction (DPE), soil vapor extraction (SVE), air sparging (AS) and enhanced in situ bioremediation.
The remediation strategy specifically planned for this site is as follows:
- Dual Phase Extraction (DPE) to remove the oil slick, Soil Vapor Extraction (SVE) and Air Sparging (AS) to control the contamination boundaries.
- Enhanced bioremediation is used when contaminant concentrations are reduced
The following actions were taken when an effective reduction of the contamination area and volume of contamination was not achieved:
- Vacuum pumping was used to lower the water table to control the extent of contamination in the unsaturated and saturated layers and to reduce the thickness of the oil slick. The average thickness of the oil slick was reduced from 77cm to 5cm and enhanced bioremediation was initiated in the downstream area as no oil slick was detected.
- Soil removal by soil vapor extraction (SVE) combined with air agitation (AS) reduced TPH from 672 tons to 315 tons.
- The area of groundwater contamination was reduced to 23,500 square meters and benzene concentrations were reduced from 23.6 mg/L to 11.0 mg/L.