An Introduction Phase 1 & Phase 2 Site Investigations and Contaminated Land

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1 An Introduction Phase 1 & Phase 2 Site Investigations and Contaminated Land CPD Presentation by Geosphere Environmental Ltd at Basepoint Business Centre, Ipswich on 25 January 2012

2 Why Undertake A Land Investigation? o To comply with Regulatory requirements (necessary) o To minimise exposure to risk (loss) (desirable)

3 Types of Land Investigation- Geotechnical o Generally undertaken as a result of a proposed development on any land o Generally not Regulatory driven (and as such may not be undertaken) o Exception Sites with difficult ground conditions or larger structures

4 Types of Land Investigation- Environmental o Assess risks posed by former and current uses of a potential site o Protect End Users of developments o Protect the wider environment o Manage risks identified on sites.

5 Definition of Contaminated Land Section 78A(2) of Part 2A of the Environmental Protection Act 1990 defines contaminated land as: any land which appears to the local authority in whose area the land is situated to be in such a condition, by reason of substances in, on or under the land, that: (a) significant harm is being caused or there is a significant possibility of such harm being caused; or (b) pollution of controlled waters is being, or is likely to be, caused.

6 EXAMPLES OF QUOTE SPECIFICATION VARIATION

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8 RECEIVED QUOTE VARIATION The first example specification was a request for a Desk Study. The second specification was far in excess of what was actually required for the site and a waste of money for the Client but the Consultant was constrained by the specification document.

9 SUGGESTED SPECIFICATION Ensure the following The site boundaries are clearly marked as below.

10 Ensure the reason for the investigation is understood o Ensure the reasons behind the requirement for the investigation is understood. o Is the investigation a planning requirement (Now often pre planning)? o Is the investigation being carried out for Due Diligence? o Is the investigation geotechnical or environmental if both, can the elements be carried out together reducing costs? o Does the overall Client understand the process?

11 o o o o o Provide clear time scales for the return of the quotation and the reports Are there any specific health and safety requirements Does the site have access constraints Provide any service information Supply of proposed development plans if available.

12 OVERVIEW OF PHASE 1 DESK STUDIES

13 Phase 1 Preliminary Risk Assessment o Environmental Objective: To produce Initial Conceptual Site Model o Geotechnical Objective: To assess the likelihood of the presence of any geo-hazards and allow for the design of intrusive investigation o Usually involves Desk Study and Site Walkover o Rarely sufficient on its own to satisfy Local Authority Planning requirements

14 Desk Study Information Sources o Historical Mapping (OS, Insurance, Tithe) o Environmental Data Searches (Water Quality, Environmental Permits, Landfills, Abstraction Licenses etc) o Petroleum Officer Reports o Geological and Hydrogeological Maps and Records o Coal Authority Reports o NRPB Radon Reports o Ecological and Archaeological Sources o Industry Archive Records

15 Information Source Examples

16 Desk Study Geotechnical and Other Information o Landslip (BGS) o Compressible/Collapsible Ground (BGS) o Shrinkable/Swelling Clay Hazards o Running Sand Hazards (BGS) o Likely Presence of Made Ground (BGS) o Flood Risk (EA) o Subsidence due to natural/man made voids (BGS/Chelsea Speleological Society/LA) o UXO Risk

17 Information Source Examples

18 Site Reconnaissance Visits o Verify the findings of the Desk Study and note additional information about the site and its environs. o Site observations include: Topography, Geological Exposures, Evidence of geohazards, Water Features, Vegetation, Ecology, Contamination, Buildings and Services. o Site staff interviews to include: history, processes, incidents etc.

19 Initial Conceptual Site Model o Based on the Desk Study and Site Reconnaissance formulate a CSM including. Sources (Made Ground/UST). Pathways (direct contact with soils/off-site migration of groundwater). Receptors (current/future site users/occupiers/nearby river). o Decide which pollution linkages are active and whether the potential for harm or pollution exists.

20 ANY QUESTIONS

21 Phase 2 Site Investigation and Generic Risk Assessment Objective - To review and update Conceptual Site Model by: o Determining ground and groundwater conditions with respect to contaminant movement and engineering properties o Determine the presence, concentration and distribution of contaminants o Characterise any potential migration pathways, including those to structural receptors o If contamination known to be present, allow delineation and design of future remediation

22 Utility Avoidance o Responsibility o Obtaining Utility Drawings - Cost and Timeframe o On Site Avoidance/Clearance Techniques o Visual Appraisal Scarring, IC, Marker Posts o Hand Excavation o CAT and Genny o Site Utility Survey including GPR o Vacuum Excavation

23 Sampling Techniques o Hand augering

24 Sampling Techniques o Window/Windowless Sampling and Dynamic Probing

25 Sampling Techniques o Window/Windowless Sampling (Continued)

26 Sampling Techniques o Trial Pitting

27 Sampling Techniques o Cable Percussion Drilling

28 Sampling Techniques o Rotary Drilling

29 Other Site Techniques

30 Water Sampling Techniques

31 Sample Collection and Preservation o Use right container and sampling method dependant upon expected contaminant or type of analysis o Take enough sample (env ~ 1kg, geo up to 25kg) o Keep cool, but not frozen (and sometimes dark) o Get to Lab ASAP avoiding samples laying over at couriers depot over the weekend o Inform lab in advance of any special sample requirements o The above are MCERTS/UKAS requirements

32 Sample Collection and Preservation

33 Generic Risk Assessment o Confirmation of active pollution linkages. o Assessment of the measured contaminant concentrations against relevant screening criteria for soil and groundwater (SGV, GAC, EQS). o SGV (and GAC) describe concentrations of contaminants in soil at which (in the Government s view) there would be no appreciable/minimal risk to human health in three modelled generic land-use scenarios. Measured concentrations above SGV (GAC) indicate potential for unacceptable risk. o SGV, GAC, EQS only applicable to one pollution linkage, others require separate assessment. o Non aqueous phase substances cannot be assessed using guideline values and again require separate assessment. o SPOSH (Part IIA) Assessments differ from minimal risk approach

34 Geotechnical Reporting o An account of the fieldwork o Exploratory hole logs o Laboratory test results o Outline of the ground and groundwater conditions o Engineering recommendations Indicative foundation type, depth, allowable loading and any special requirements Floor slab type and void thickness Chemical aggressiveness of the soil Highway design Retaining wall design Earthworks o Recommendations for further work

35 ANY QUESTIONS

36 Phase 3 Detailed Risk Assessment o Firstly may include additional site work e.g. a further groundwater monitoring visit incorporating hydraulic conductivity testing. o Involves the running of commercially and freely available environmental fate and transport models, using site specific input data, to derive site specific assessment criteria or SSAC. o Comparison of SSAC with contaminant concentrations assesses the potential for unacceptable risk at the site. If remediation is still required, SSAC may act as clean up targets. o Most common (and freely available) models are CLEA and SNIFFER for risks to HH from soils and Remedial Targets Worksheet for risks to water receptors from soils and groundwater (simple aquifer systems only).

37 Options Appraisal o The process to select the most effective remediation method(s) with respect to the following criteria: The degree in which risks need to be reduced and controlled Available timeframe Practicality and maintainability of the technique Technical effectiveness Sustainability Cost Additional benefits of the strategy Legal, financial and commercial issues o Often undertaken using an algorithmic approach

38 Remediation o Objective: To break or modify active pollution linkages to mitigate the unacceptable risks presented to sensitive receptors o Broadly 3 categories: Engineering based methods Process based methods Natural attenuation

39 Engineering Based Methods o Soils Excavation with off- and on-site disposal Excavation with ex-situ processing Soil stabilisation/solidification o Soils and Liquids Containment

40 Process Based Methods o Soils Soil vapour extraction/bioventing o Liquids Product and groundwater extraction (P + T) Air sparge Permeable reactive barriers o Soils and Liquids Dual phase extraction/vacuum enhanced recovery

41 Natural Attenuation o Soils and Liquids Phytoremediation o Liquids Monitored Natural Attenuation Enhanced Natural Attenuation

42 Any Questions?