Environmental Site Assessment at TPH Contaminated Site: A Malaysian Case Study

Abstract

This paper introduces the Malaysian Contaminated Land Management and Control Guidelines and one case study on Environmental Site Assessment (ESA) conducted at one contaminated site in Malaysia. The site was contaminated with spent transformer oil, i.e. Total Petroleum Hydrocarbons (TPH). Five types of environmental samples were collected, i.e. surface soil, surface water, subsurface soil, groundwater and air. Samples were analysed for Total Petroleum Hydrocarbons (TPH) and fractioned into different carbon fractions namely C₆-C₉, C₁₀-C₁₄, C₁₅-C₂₈ and C₂₉-C₃₆. Risk Assessment was also performed utilising Risk Based Corrective Action (RBCA) method. The drilling bore-log showed that the site is located on residual weathered meta-sediment rock with thick clayey silt. The study discovered the spent oil was trapped inside the made layer gravel within ~22 to 60 cm on top of the residual clayey silt. Chemical results showed TPH in surface soils ranged from 1310 to 26747 mg/kg with the average value of 17200 mg/kg. In surface water (inside the contaminated area), the concentration of TPH was measured in between of 1 to 2646 mg/L (averaging 454 mg/L). RBCA analysis showed that indoor and outdoor air were the pathways with lower risk level with all risk values (Hazard Quotient, HQ) below the upper limit of 1.0. Baseline risk level for soil is slightly higher than the upper limit level with a risk of 1.5. Critical pathway is through groundwater with baseline risk level significantly higher than the upper risk level with a value of 5.4E+6.