Soil & Groundwater Remediation (Clean-Up)
Service: Phase 3 Soil Remediation
Location: Foundry Site, THAILAND
Client: European Consultancy
Project Value: Confidential
SLP Environmental was commissioned by a North American client to undertake Phase 1 and 2 Environmental Site Assessments at a steel foundry site located in Eastern Thailand. The Phase 2 Environmental Site Assessment identified soil contamination in one sector of the site and SLP were consequently commissioned to design, implement, manage and verify a Phase 3 Soil Remediation package of works for the site.
The primary objective of the soil remediation works was to reduce risks to environmental and human receptors to acceptable levels and SLP formulated an Environmental Remediation Strategy for the site that comprised; i) the controlled excavation of the contaminated material, ii) the ex-situ stabilization of the contaminated material to reduce contaminant mobility, iii) the disposal of the stabilized material to a licensed hazardous waste landfill and, iv) the backfilling of the excavation with clean imported materials.
Following the excavation of the contaminated materials the base of the remediati
on excavation was subject to sampling and rapid turnaround chemical testing to verify that the residual contaminant concentrations were below the Remediation Target Values (RTVs) developed for the project. Any area recording exceedances of the project RTVs were subject to further localised excavation and retesting until compliance with the project RTVs was achieved. Once it was verified by SLP that the residual contaminant concentrations were below the project RTVs the excavated soils were replaced with a chemically acceptable granular fill material which was then compacted to a suitable standard to enable continued current operations at the facility.
The contaminated soils were transported to a specialist waste treatment and disposal facility where they were stabilized with proprietary stabilizing agents prior to their disposal in a licensed hazardous waste landfill. A cradle to grave waste transfer manifest regime was strictly implemented and monitored during the works and SLP Environmental produced a detailed Remediation Validation Report for the project that detailed the works that were undertaken and presented the supporting evidence to verify that the site had been successfully remediated and no longer presented a risk to environmental and/or human receptors. SLP Environmental offer site remediation (decontamination) services in Cambodia, Indonesia, Lao, Malaysia, Singapore, Sri Lanka, Thailand and Vietnam.
Service: Technical Expert & Project Verification
Services, Large Soil Remediation Scheme
Location: Central Bangkok, THAILAND
Client: International Government
Project Value: Confidential
SLP Environmental was appointed by the Australian Government to provide technical expert, project oversight and validation testing and remediation verification services for a Phase 3 Soil Remediation scheme being undertaken by others on a large piece of prime real estate located in Central Bangkok, Thailand.
SLP were originally commissioned to undertake a Phase 1 Environmental Site Assessment of the study site and this identified that the site had been host to several former potentially contaminative landuses over the last 60-70 years. SLP were subsequently commissioned to undertake a Phase 2 Geoenvironmental Site Investigation which established that the shallow soils contained inorganic contaminant concentrations at levels that represented a potential risk to the health of future site users.
The site vendor has commissioned a local contractor to undertake the soil remediation works on their behalf and our client decided to appoint an independent environmental consultant in a quality assurance role. SLP Environmental will oversee the remediation works and conduct an independent validation soil sampling and laboratory testing exercise upon their completion to verify (or otherwise) that the risk conditions have been satisfactorily reduced and that the proposed land transaction deal can proceed. The soil remediation works commenced in September 2011 and are programmed for completion late December 2011.
Service: Manufactured Gas Plant Remediation
Utilising In-Situ Chemical Oxidation
Location: Solihull Gasworks, UK
Client: National Grid
Project Value: c.$6million
SLP personnel were responsible for the design and delivery of a soil and groundwater remediation scheme at a 10ha site in the West Midlands. A large manufactured gasworks was historically located on the site although it was later re-developed to accommodate the clients' regional headquarters. The client commissioned Phase 1 and 2 Land Quality assessments as a part of a pre-divestment due diligence exercise and these identified the presence of numerous below ground tanks containing gasworks wastes as well as localised soil and groundwater contamination.
SLP personnel therefore undertook detailed quantitative risk assessment modelling which confirmed that significant pollutant linkages were present and risk management measures were required. The primary contaminants of concern (CoC) comprised PAHs, BTEX compounds, TPH fractions, cyanide, arsenic and ammoniacal nitrogen, which were present in free, sorbed and dissolved phases in the saturated and unsaturated zones. The primary identified pathways were via solute transport and the sensitive receptors water quality in the shallow aquifer and a neighbouring river. The modelling exercises generated the soil and groundwater remedial targets, which were used to both delineate the areas requiring treatment and subsequently validate the efficacy of the implemented remedial scheme.
A remediation options appraisal was undertaken for each pollutant linkage and this led to the formulation of a Remediation Strategy that included the excavation and ex-situ treatment of approximately 50,000m3 of unsaturated soils and the installation of Europe's largest in-situ chemical oxidation (ISCO) system to address sorbed and dissolved phase organic contamination in the saturated zone. Following the bulk excavation of the unsaturated component the remedial zone was sub-divided into treatment cells where hydraulic manipulation ensured that the oxidant (Fenton's Reagent) and any process metabolites were kept in a closed system. 
Field monitoring of the primary CoC concentrations was undertaken during treatment operations and when these indicated CoC concentrations were below the relevant risk criteria operations were halted and the cell left to stabilise for a week before the validation samples were collected and submitted to a certified laboratory for analysis. The treatment duration in each cell was largely dictated by the organic contaminant mass present and the hydraulic conductivity of the aquifer matrix, but averaged out at about ten days per cell.
The ISCO system proved to be an extremely rapid method of reducing organic contaminant mass in the shallow aquifer and had the added advantage of addressing both the sorbed and dissolved phases. The entire remediation project was completed short of deadline and within budget, and close liaison with the regulatory authorities throughout the various work stages ensured that all the necessary sign-offs were received shortly after completion allowing the client to progress the sale of the site. The site has now been redeveloped for a residential end use comprising houses and apartments.
Service: Gasworks Remediation
Location: Cambridge Gasworks, UK
Client: Tesco Stores Limited
Project Value: c.$15million
SLP personnel undertook a critical monitoring review role of the remediation works undertaken at Cambridge’s former manufactured gas plant on behalf of the site purchaser. The remediation works across the 5 hectare site were required to facilitate the construction of residential and retail development platforms adjacent to the River Cam.
The remediation strategy for the contaminated soil (contaminants included coal tar, spent oxides, PAH's, BTEX, cyanide and ammoniacal nitrogen) comprised two distinct approaches for the residential and retail components of the scheme. The works included the removal of below ground tar and liquor tanks, gas holder bases and other process plant sub-structures & pipe work and the construction of a bentonite containment wall on three sides of the site to prevent the migration of contaminated waters onto the adjacent residential site and towards the River Cam. Residual contamination was capped with a ‘bentomat’ geosynthetic liner and topped with drainage media and a granular blanket to development formation level. Within the residential redevelopment area the former gas holder was broken out and an infilled brick pit was excavated (depth up to 10 metres) to the natural clay interface and backfilled with granular material to development formation level. Other proposals for the site included new cycling routes through the site and a memorial garden for the community.
Service: Chlorinated Solvents Remediation
Location: White Spirit Manufacturing Works, UK
Client: Confidential
Project Value: $1.2million SLP personnel designed and managed the Phase 2 Site Investigation works and Phase 3 Remediation works at a former white spirit factory in the UK. Upon completion of the soil, groundwater and land gas
characterisation phase detailed quantitative risk assessment (QRA) modelling for human health and controlled waters was undertaken to derive the soil and groundwater remedial targets that would underpin the remedial scheme.
The project involved detailed consultations with the statutory regulators and other stakeholders and the generation of outline cost plans for numerous remedial scenarios. The remediation works comprised the removal of below ground tanks and QRA identified zonal areas of unacceptable soil contamination followed by air sparging of the shallow aquifer. The completion reports for the works were subsequently approved and discharged by the EA and the project was delivered to programme and budget.
Service: Heavy Metal Remediation Project
Location: Former Metal Works, UK
Client: Barratt Homes Limited
Project Value: $1million
SLP personnel were responsible for the site investigation, remedial design and implementation of the remediation works at a former Metal Works site in London. Specific tasks included the completion of the remediation specification, liaison with the statutory authorities, applying for landfill tax and waste exemption licenses, supervising the remedial works on site and undertaking the validation works across the site. Key challenges included the relocation of great crested newts communities, which had colonised overgrown areas of the site and moving them to suitable habitats off-site. The project was completed on programme and budget and the site redeveloped for housing.
Service: Asbestos Removal and Demolition Project
Location: Precious Metal Refinery, UK
Client: London Development Agency
Project Value: $800,000
SLP personnel were responsible for the design and implementation of a demolition and asbestos removal enabling works project including the production of the Specification, Tender and Contract Documents on behalf of the client and supervision of the works themselves. Project constraints included an infilled tailings lagoon, which inhibited the movement of heavy plant vehicles and the presence of a river wall on the site. The project was completed successfully and complied with all health and safety standards and requirements.