PFAS Risk Screening Project (Phase 4)

Lot 1: To develop a guide aimed at those involved in the regulation of sites of concern due to the impact, or potential impact, from PAS and associated chemicals. Acting as a reference guide which staff can refer to when faced with sites highlighted under voluntary schemes, regulatory regimes, or pollution incidents. Providing background to the problem, the nature and characteristics of these chemicals, and the tailored approach necessary to best assess the risk, apply regulatory controls and ultimately implement mitigation measures (if necessary). A step-by-step guide adopting the classic land contamination evaluation approach indicating how at each stage of site assessment, the site evaluation strategy should be conducted when considering contaminants of this nature. To collaborate and share information with the other tasks under Phase 4 and link back to the outputs and conclusions from preceding phases.

Lot 2: To focus on sites of concern that have been highlighted by the GIS model developed under previous project phases or identified independently by colleagues. To progress a number of desk-based site assessments utilizing all available information, both internally and from wider external research. Aiming to deliver a comprehensive independent desk study report for each the highlighted sites providing background context, assessment of the evidence base, development of a robust conceptual site model, and recommendations for further, potentially more in-depth or site-based investigation. It is likely that any subsequent site evaluation will be conducted under Part 2A of the Environmental Protection Act 1990, and so the approach adopted for site evaluation should follow Part 2A procedures. In addition to desk-based site assessment activities mentioned above, we have already built-up sufficient evidence on a number of particular sites to justify on-site investigation works. Under Lot 2 we are seeking a specialist consultancy to deliver an intrusive site investigation on one of these highlighted sites, to further refine the conceptual site model and deliver conclusions under the Part 2A regulatory regime. Whilst PFAS are the primary contaminants of concern, in accordance with Part 2A, all potential contaminant linkages should be thoroughly evaluated. To collaborate and share information with the other tasks under Phase 4 and link back to the outputs and conclusions from preceding phases.

Lot 3: To build on the outputs of Phase 3 which, utilizing the results generated by the GIS model, aimed to categorise and quantify the number of potential problem PFAS sites across England. To assess the recommendations from this Phase 3 task, and develop an approach and ultimately deliver a report, detailing the nature of the PFAS problem across the Country together will a mechanism for deriving costs to highlight the financial scale and burden of the problem. To collaborate and share information with the other tasks under Phase 4 and link back to the outputs and conclusions from preceding phases.

Lot 4: Phase 3 included an extensive monitoring exercise for water and leachate from a wide variety of landfill facilities. This ran in parallel with a DEFRA initiated landfill study. The aim was to assess PFAS and wider POPs generation and potential release into the environment. Lot 4 aims to build on this work and focus in on specific emissions from landfills to ascertain key release mechanisms for this family of chemicals. The sub tasks under Lot 4 include: • Assessment of pre and post treated leachate to evaluate PFAS component o Some studies have shown that on-site treatment can have little or no effect on PFAS substances within leachate. These leachates are then discharged to either sewage or wastewater treatment works either by direct sewer connection or tanker transfer. This study aims to assess pre and post treatment concentrations and what levels are making their way to treatment works. It will involve sampling from key locations at a pre-selected number of landfill facilities and the receiving water treatment works. • Assessment of sludges produced and POPs component o Whilst PFAS can remain largely untreated by on-site treatment facilities, many POPs are removed and most likely end up in the resulting sludges. The relative proportion is unknown. And the risk from this contaminant loading to environmental media from disposal of these sludges is also unknown. This study aims to provide additional detail by sampling the sludges from a number of landfill treatment plants and at either the point of disposal or at other intermediate treatment facilities to quantify the mass of particular POPs being released to the environment (e.g. via land spreading) and/or being destroyed at other treatment facilities. • Assessment of POPs release into GW from older unlined facilities o This task aims to assess whether PFAS and/or other POPs are being released to the environment via contaminant migration from unlined older (dilute and disperse) landfills into the underlying and surrounding groundwaters (and/or surface waters). The task would involve sampling of the raw leachate and groundwater both up and down hydraulic gradient of the landfill site. • Study of PFAS in gaseous emissions o This sub task aims to qualify / quantify the potential release of PFAS in trace gases released at landfills from the combustion gas treatment systems (landfill engines and flares) and gasses passively venting from the landfill itself. The task will involve sampling from various key locations likely to include: Raw gas at the well head or manifold; sampling the gas condensate within the gas collection pipework; sampling the soils downwind of the combustion treatment plant and beyond the landfill site boundary; and, sampling of the waste oils and slippage combustion products from the gas engine. To collaborate and share information with the other tasks under Phase 4 and link back to the outputs and conclusions from preceding phases.

Lot 5: Whilst more information is becoming available on PFAS and related substances in the water environment (groundwater and surface water) there is still little information on background PFAS levels within the soil environment. In order to assess the scale of the problem, to develop a countrywide picture, and to help evaluate risk, a comprehensive study of background concentrations is considered necessary. This would be conducted in collaboration with the British Geological Society (BGS) as a sub-contractor to the main Contractor, who would help facilitate mapping, provide geological context and potentially access to archived soil samples. It is currently anticipated that this task would include widespread soil sampling from a representative range of environments. To collaborate and share information with the other tasks under Phase 4 and link back to the outputs and conclusions from preceding phases.