Asbestos in soils Surveys, site investigations & sampling Good Practice. James Macfarlane Asbestos Manager Land Remediation

Transcription

1 Asbestos in soils Surveys, site investigations & sampling Good Practice James Macfarlane Asbestos Manager Land Remediation

2 Spot the Asbestos

3 The Main Difficulties Does not leach; Only UKAS Polarised Light Microscopy (PLM) can accurately confirm asbestos presence (No site based tests); >4000 of different products, even experienced surveyors can be caught out with something they have never seen before. Non-Asbestos look-a-likes (Calcium based insulation) Once binding material is degraded fibres will remain; Asbestos is very difficult to spot in the ground;

4 Examples of ACM in Soils

5 Managing and Working with Asbestos (L143/CAR2012) Asbestos: The Survey Guide (HSG264) The Analysts Guide (HSG248) All documents are focused on the risk, identification and removal of ACM associated with asbestos in buildings; Only minor mention of soils and the surrounding land ( Curtilage of the property/land); Currently, the identification asbestos contaminated soils appears to be the opposite of the guidance given in the ACOP (L143 Managing and working with asbestos) The surveyors guide (HSG264) is written for building surveys. HSG264 focus on the minimal disruption of ACM during investigation and sampling techniques to prevent exposure Very difficult when excavating soils The analysts guide (HSG248) will be reissued in early 2016 with a consultation period in September 2015 A section on soils is reported to be present.

6 Managing and working with Asbestos (L143) & The Control of Asbestos Regulations 2012 (CAR2012) (Source: L143 Managing and working with asbestos)

7 Is asbestos liable to be present? Asbestos Preliminary Risk Assessment (PRA) A thorough desk top study should give a basis to decide if Asbestos is likely to be a major contaminate of concern (CoC); Collection and review documentary evidence (Not an exhaustive list); o Old Type 1, 2 or 3 Building surveys; o Buildings asbestos register (gained from local fire brigade?); o Historic service plans (Heating pipes possible insulation); o Location of boiler houses (Very important Lots of Asbestos); o The Demolition Asbestos Surveys; o UKAS Clearance certificates post removals; o H&S File / Validation reports; o Other geotechnical investigations; o Bulk and Gravimetric Analysis data; o Historical land use (Commercial? Industrial? Residential?); o What was being manufactured? (Filtration factory); o Details of fly tipped waste/soils or imported aggregates; o Known location of made ground & demolition arising's; o Any landfill or buried waste licenses. Compile a suitable Preliminary Risk Assessment (PRA) to decide if a site reconnaissance is required. If it is then the information can also be used to compile the scope, methodology and control measures to carry out the reconnaissance. Further information on PRA s in CLR11 (Environment Agency 2004)

8 Is asbestos liable to be present? Using the information from the Asbestos specific Desktop Study and Site Reconnaissance update the Preliminary risk assessment (PRA) & Conceptual Site Model (CSM); The PRA & CSM will aid in designing and implement a thorough field investigation that complies with CAR2012; Surveying and the collection of asbestos samples in buildings is exempt from the notification (i.e. ASB5 notification is not be required). In general so will sampling soils for asbestos, as long as the staff are competent and appropriately protected to undertake the sampling activities; The CSM should include an assessment of if the investigation in terms of the potential to notify the investigation works themselves (NNLW / LW). For example, did the site ever manufacture asbestos products? Is it a former landfill? As mechanical excavation is likely to be required for Asbestos Containing Soils, if unacceptable risks are identified in the CSM, additional control measures and decontamination provisions will be required;

9 Case Study Former Filtration Factory, Guildford Desk top study Demo Contractor carrying out crushing and screening operations following demolition. Halted after identification of Asbestos Containing Soils (Asbestos Cement) during work. Demo Contractor had spread contamination from demolition arising's and the SW corner across the site during excavation and screening activities; Demo Contractor did not have any information on discrete location of ACM or any site investigation; Client unable to provide any previous asbestos surveys or information; Costs to the client that could have been avoided had asbestos been delineated early in the project.

10 Site Reconnaissance Site Reconnaissance Systematic walk of the site to visually inspect the surface; Vegetated areas difficult to inspect; Needs to be carried out by a trained/competent team that has experience with asbestos identification (BOHS - P402) and brownfield sites; Ensure CAR2012 is complied with, but unlikely to be notifiable; Identify type of ACM, distribution, soil type, likely moisture content; Identify any immediate risks; Limited sampling at this stage Bulk Identification suitable. Minimal RPE/PPE; Primary Decontamination Bay; Surface inspection only; Surface inspection of SW corner identified an unlicensed asbestos waste cell in SW corner;

11 Site Reconnaissance

12 Field Investigation - Issues to consider SW corner identified as the primary area of concern; Mechanical investigation the only option to successfully delineate the extent of the Asbestos Containing Soils in the SW corner; With the type of licensable materials present e.g. ball of insulation identified in the site reconnaissance, primary decontamination would not be sufficient to successfully comply with CAR2012; How can you address concern by local resident? An open discussion with the local residents was required to alleviate fears of the A word; SI work would be required to assess the suitability of the remaining stockpiles for site retention; Engage with the local HSE prior to works to decide if notification would be require, despite exemption for survey/sampling works under CAR2012.

13 Trial Pit/Trench Location Scale ~5m

14 Asbestos Quantification Samples Gaining a representative and homogenous sample is a skill and requires significant agitation of potentially contaminated soils; Must be undertaken by suitably trained operatives with appropriate RPE & PPE ( in accordance with CAR2012); Training needs analysis allowed Hydrock to compile a bespoke Asbestos in soils safe sampling course; All Hydrock geoscience staff are carrying out this training.

15 - Decontamination and Segregation Site reconnaissance displayed that that primary decontamination alone would not be sufficient; Materials SW corner identified as significant possibility of significant harm (SPOSH); Highly fibrous insulation and close proximity of residential properties.

16 - Protect ALL staff not just ground operatives Ensure training, experience and competency is adequate to the task; P402 surveyor with experience of asbestos in soils is critical to identify the product and sample accordingly; In this case UKATA Category C machine operators; Ensure training needs analysis has identified any requirement for supplementary training.

17 - Ensure control measures are effective. Ensure public and other site personnel are protected (Dust suppression techniques) Air monitoring was suitable in this case but may not always be useful. When using air monitoring close proximity to source is best; What limit of detection is required? Would scanning electron microscope be applicable? Available/Adequate supply of water is paramount!

18 - Leaving the site safe Can be difficult to assess depth of contamination without actually excavating Asbestos Containing Soils (A licensable activity?); Any surface ACM post SI must be left in a satisfactory condition awaiting remediation; Hand picking Clean capping Barrier layer Decontamination of all plant with the potential for contamination; Including air tests to plant cabs and decontamination units; Ready for Remediation.

19 Case Study Plymouth School Asbestos Containing Soils below concrete slab

20 Case Study Plymouth School Desk top study & Reconnaissance Contamination below slab not identified by previous contractor during demolition of the school; Wide spread contamination to soils a legacy of construction methods at the time (1960 s); Loose insulation and cement within soils and remaining below concrete; Purpose was a contractor lead SI to define a suitable working method to satisfy CAR12012; High visibility and concern from local residents and HSE.

21 Case Study Former Plymouth School Stage 1 - Site Investigation Total of 30 core samples taken initially to assess the extent of contamination across the 3 areas; Slab B >90% of core samples positive for ACM; Slab A and C <20% of cores positive fro ACM. Depth of contamination fairly uniform at ~0.20m

22 Case Study Plymouth School Stage 1 - Site Investigation Bag # Material Type Asbestos Type GS11021/02 Insulation Chrysotile

23 Case Study Plymouth School Stage 2 - Site Investigation

24 Case Study Plymouth School Stage 3

25 Summary Asbestos Site Investigations should be performed early in a project to ensure geotechnical/ground workers are not exposed to Asbestos containing soil and CAR2012 is complied with; Accurate site information on asbestos distribution will allow detailed & robust remediation strategies to be produced; All site reconnaissance/investigations need to comply with general health and safety requirements and CAR2012 and be based on PRA; All personnel involved should be appropriately trained, experienced, competent, face fit tested and have adequate knowledge of decontamination procedures (Surveyors experience is paramount); P402 are a must for a robust site investigation But a P402 surveyor with experience of asbestos in soil/contaminated land is key. Gravimetric sampling alone is not sufficient multiple lines of evidence are required to build up a case for DQRA and long term exposure risks; Fibre release / Airborne concentrations - f/ml.hours /years; Sustainability; Land use Current vs. Future; Capping layers; Transmission to internal environments;