2                                            Site Appraisal

2.1                                      Site Appraisal and Review of Historical Site Investigation Data

ERM conducted a walkthrough of the proposed project area on 4 October 2005 and identified potential areas where fuel storage and transmission facilities were located, as follows:

·            Two aboveground fuel storage tanks, aboveground steel structures of 250 m3 underlain and surrounded with concrete bunding.  Visual inspection of the concrete bunding showed no evidence of oil leakage or spillage;

·            Fuel pipelines connecting between the fuel tanks and the fuel oil transmission pump houses.  The pipes are located in underground trenches.  Initial visual inspection of the areas showed no evidence of oil leakage or spillage;

·            Stormwater collection and oil separation sump.  The reinforced concrete tanks were located in ground.  Visual inspection of the area showed no evidence of oil leakage;

Locations of these facilities are presented in site layout map (Figure 2.1a) attached.  The Nos. 4 & 5 Light Oil Tanks were designed according to the Code of Practice issued by the Building Authority.  The oil tanks foundations were made of concrete raft footing, the surrounding reinforced-concrete slabs with bund walls constructed of reinforced concrete.  The bund walls were designed to provide containment volumes of not less than the maximum operating capacity of the oil tank and the containment was fitted with drain channels connecting to a sump pit, where the oil/oily drain will be further diverted (operated by manual valve) to the oil separator.  An oil detector has been installed to detect any oil spillage and alarm will be generated at the control room for notification and further action.  The oil separator was constructed with reinforced concrete.

Visual inspection of the tanks, pipeline trenches and oil separator areas identified no apparent evidence of oil staining on the concrete pavement or in the drainage trenches.  HEC confirmed that no major spillage/leakage of oils or chemicals occurred at the Site since the commissioning of the tanks in 1990.  Minor spills within the bund areas during maintenance were reportedly collected and then further processed in the oil separator.

No soil and groundwater contamination studies have been conducted at the Site.

 

2.2                                      Potential Soil and Groundwater Contamination

Based on the review of site information and the walkthrough the potential sources of soil and groundwater contamination from the Nos. 4 & 5 Light Oil Tanks and oil separator included the oil storage, transmission facilities and oil separator sump as described in Section 2.1.  The facilities may be considered potential sources of land contamination due to the following reasons, but not limited to:

·          Leakage and/or spillage from the oil tanks to the underlying soil and groundwater;

·          Spillage of oils during the filling of the tanks which may enter the surrounding areas; and

·          Leakage from the in-ground oil separator to the surrounding soil and groundwater.

The likely contaminants associated with the fuel storage facilities include, petroleum hydrocarbons (TPH), simple aromatic hydrocarbons (BTEX) and polycyclic aromatic hydrocarbons (PAHs).