Colgate Palmolive Philippines Inc.

Andrew.Stewart Limited was engaged to conduct Phase 2 and Phase 3 investigations as part of a due diligence process for site divestment by Colgate Palmolive Inc. who had operated on the property for over 50 years, manufacturing personal care and laundry products.   The site will be re-developed as part of ‘de-industrialisation’ and upgrading of the Makati City, Manila.

Soils within a former tank farm located on the western side of the site were found  to contain elevated levels of petroleum Hydrocarbons and Polycyclic Aromatic Hydrocarbons.    The hydrocarbons present were composed predominantly of fuel (bunker) oils as well as de-graded diesel.  

PAH concentrations at a number of locations within the affected area exceeded residential and commercial human health investigation levels.     Land use in the area is mixed residential and commercial, and as soil exposure levels are unknown until re-development is complete, soil guidelines for the most sensitive end use were selected as remediation targets.

A risk assessment to evaluate the likelihood of potential groundwater contamination was also carried out as the site is near a river and groundwater is abstracted for potable use in the area.

Challenges/ Unusual Features

Remediation work included:

• Contaminated groundwater removal and containment
• Demolition and removal of multiple concrete slabs, in ground concrete structures and surface paving
• Excavation and on-site storage of contaminated soil and materials
• Segregation of impacted and non-impacted soil to minimise treatment and disposal costs
• Removal of soil contamination around and beneath a 35 kW 3-phase power cable encasement crossing one corner of the affected area
• Monitoring and if required, remediation of groundwater
• Re-grading of the site with clean materials won from the excavation works and soil imported from off-site sources

Quantities

In order to minimise the impact of contaminated soils and groundwater on clean materials, close supervision of excavation operations and routine validation testing was undertaken as remediation was progressed.   Uncontaminated material was transferred immediately to already cleaned sections, and sumps established to divert groundwater affected by phase separated and dissolved hydrocarbons away from working faces.   A total of 600 tonnes of contaminated soil was stockpiled in dedicated covered facilities for later treatment.

OSH

Hot work within the excavation was prohibited and all machinery fitted with spark arrestors.   Entry into confined spaces was conducted in accordance with New Zealand Health and Safety at Work Act specifications HSE 1997.  All work was supervised and directed by Site Safe Accredited ASL staff.