CONTAMINATED LAND WORKSHOP 2014: SCOPING PSIs AND DSIs. P A T TLE DELAMORE P A RTNERS LTD solutions for your environment

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1 CONTAMINATED LAND WORKSHOP 2014: SCOPING PSIs AND DSIs

2 Ground to be Covered Reasons for preliminary site investigations (PSI) When a formal PSI is not required PSI contents and information sources Sampling investigations (not just DSIs) Detailed site investigations (DSI) under the NES Scoping a DSI Writing a DSI

3 The purpose of a Preliminary Site Investigation (PSI) Non-regulatory purpose an owner wanting to know the status of the land for whatever reason and/or to pass on information to occupiers or potential purchasers. Regulatory purpose only two reasons under the NES: 1. To determine whether land is HAIL land (as defined by reg. 5(7)) and therefore whether the NES may apply. 2. If the land is HAIL, and only for change of use or subdivision, to provide an expert (SQEP) opinion on whether a risk to human health might arise. The expert context-based NES letter (PSI-lite) showing NES n/a (reg. 5(6)). Legitimacy, council discretion?

4 When a formal PSI is not required If the land is clearly HAIL, there is generally no point in writing a formal PSI if: Change of use and risk to human health cannot be eliminated by desktop assessment; and/or Soil disturbance or disposal is in excess of PA. Requiring a PSI in such cases is an unnecessary expense as the report will conclude the land is clearly HAIL and needs sampling. However, some PSI-type enquiries are useful for developing a conceptual site model and sampling plan for a DSI, or to contribute background to an AEE.

5 PSI Enquiries CLMG1 provides a check list, but some sources of information are better (worth more effort) than others. Remember, the primary objective is to identify locations/extent of potentially contaminating activities. Best sources typically people, owner and official files, and historical aerial photographs. Weight of evidence. Knowledge of contaminating activities critical (SQEP). If HAIL and sensitive land use, it is difficult to show no potential human health risk probably need a DSI. PSI and a few samples do not fit easily under the regs. A few samples not generally sufficient to show no risk.

6 Reasons for a Sampling Investigations Many potential reasons for sampling investigations: Non-regulatory reasons (council review not appropriate): Benchmarking for owner information. Benchmarking for potential lessee or purchaser. Regulatory but non-nes reasons: Benchmarking for worker H&S. Benchmarking for discharge consent application or as a condition of discharge consent A DSI under the NES. To guide remediation.

7 Detailed Site Investigations under the NES If HAIL: to show the soil is at background NES n/a. If HAIL: to assess health risk for change of use or subdivision when risk cannot be eliminated by a PSI. However, there is nothing in the NES requiring a DSI for a discretionary consent. Could be a consent condition. But may be difficult for some (complex) sites for a council to assess the consent application without a DSI. Validation sampling is a type of DSI and should be treated as such. Needs to be planned properly. A DSI usually aimed at a particular project and may not directly transfer to some other purpose/party - reinterpret

8 Scoping a DSI Need enough information to: Formulate a Conceptual Site Model. What/who is at risk, by what and how? Understand likely contaminants of concern (CoCs). Have some understanding of contaminant distribution or, if not, information to decide on sampling pattern. What is the budget? Inevitable compromises. Future site use will determine how exposure will occur and over what area exposure area. Future site use will determine soil standards/guidelines and therefore laboratory detection limits.

9 Other Random DSI Thoughts Samples (individually and collectively) must be representative of what a person would be exposed to for the particular land use scenario. Getting the sampling right is just as important as getting the lab analysis right, but often not done as well. A DSI is not necessarily required for soil disposal. Selective sampling is often sufficient because it is often about satisfying the disposal location operator, not onsite health.

10 Writing a DSI Generally in accordance with CLMG1. Help your reader understand photographs, diagrams, tabulated data for key contaminants (not everything). Often non-specialist reader. Provide enough context and background to bring your reader up to speed. Provide the CSM and sampling rationale. State your assumptions where these are important for the data interpretation and conclusions.

11 Questions for Exercise 1. What is the hazard (or hazards)? 2. Who are the receptors? 3. Is there a pathway (or pathways) between each of the hazards and the receptors and if so, what? (Note: the absence of one or more of the hazard, pathway or receptor means there can be no risk). 4. What are the likely contaminants for each complete hazard pathway receptor linkage? 5. The actual or proposed land use doesn t necessarily exactly match the standard land use scenarios. What land use scenarios are appropriate for selecting the soil standards/guideline numbers? 6. Prepare a sampling plan (sample locations, analytes) for one major complete hazard pathway receptor linkage.