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Development of Sampling and Analysis Programs

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This Guideline for Developing Sampling and Analysis Programs incorporates the earlier draft Guidelines for Assessment of Sites Containing Underground Storage Tanks (DEP, 2000) and earlier draft Guidelines for Assessment of Contaminated Sites for Development of Sampling and Analysis Programs (DEP, 2000 ) and has been prepared by the Department of Environmental Protection (DEP) to assist consultants, local authorities, industry and other interested parties in the assessment of contaminated sites in Western Australia (WA). This guidance provides an indication of the methods and work required when developing a sampling and analysis program (SAP) for the investigation and validation of sites, including those containing underground storage tanks (USTs).

TABLE 1.  OVERVIEW OF SAMPLING REQUIREMENTS  8
TABLE 1. OVERVIEW OF SAMPLING REQUIREMENTS 8

GOAL

SCOPE

HEALTH & SAFETY

Copies of HSEPs must be forwarded to WorkSafe Western Australia prior to commencing work on site, along with notification of any work on site. WorkSafe Western Australia should be contacted for more information on on-site work notification and HSEP requirements.

STAGED APPROACH TO SITE INVESTIGATIONS

If the site under investigation is on a mining site as defined in the Mine Safety and Inspection Act 1994, a copy of the HSEP must be filed with the Department of Mineral and Petroleum Resources (DMPR). DSIs can be completed in a number of stages, depending on the size or complexity of the site.

RELEVANT REFERENCES

Difficulties related to the quality of information, sample parameters and distribution, established survey levels and environmentally sensitive issues can be resolved in the early stages of the survey. Submitting reports upon completion of each of the survey phases also allows site survey and management objectives to be developed in consultation with the DEP prior to commencing the next survey phase.

SAMPLING AND ANALYSIS PROGRAM DESIGN

  • INTRODUCTION
  • OBJECTIVES OF SAMPLING AND DATA COLLECTION
  • SAMPLING REQUIREMENTS
  • CHOICE OF ANALYTES
  • APPROPRIATE SAMPLING METHODS .1 Factors to be Considered
    • Composite Sampling
  • SAMPLE IDENTIFICATION, PRESERVATION, TRANSPORTATION AND STORAGE .1 Sample Identification
  • SAMPLE PRESERVATION, TRANSPORTATION AND STORAGE
  • UNCERTAINTY OF SAMPLING
  • SAMPLING AND REMEDIAL WASTE DISPOSAL

The rationale for using the fluency test procedure should be provided and used on a case-by-case basis. A SAP should be designed to minimize uncertainty based on a sound understanding of the site and the pollutants of concern.

QUALITY ASSURANCE/QUALITY CONTROL

  • FIELD QUALITY ASSURANCE/QUALITY CONTROL The minimum field QA/QC procedures that should be performed are
    • Quality Control Samples
  • LABORATORY QUALITY ASSURANCE/QUALITY CONTROL
  • CHAIN OF CUSTODY
  • DATA REVIEW

Information on QA/QC methods should be obtained from the designated laboratory prior to sampling to ensure they meet the requirements of SAP. After receiving field and/or laboratory data, a detailed review of the data must be conducted.

TABLE 2.  QUALITY CONTROL SAMPLES
TABLE 2. QUALITY CONTROL SAMPLES

SOIL SAMPLING DESIGN

INTRODUCTION AND OBJECTIVES

SOIL SAMPLING LOCATIONS .1 Pattern Types

  • Number of Samples
  • Sampling Depth
  • Field Rankings and Headspace Analysis
  • Sampling from Stockpiles and Clean Fill

Selection of sampling points should be based on site knowledge, professional judgment and where applicable, statistical analysis. Detailed justification of the number and locations of sampling points should be provided in relation to the site layout, areas of potential contamination, contaminant migration characteristics, site geology/hydrogeology, etc. Boreholes should be geologically logged by a competent professional (reference can be made to AS/NZS The Storage and Handling of Toxic Substances (AS/NZS) and AS Geotechnical Site Investigations (AS for the Unified Classification System for Soils), and field classified on soil of visual and olfactory examination.

Sampling from stockpiled material to be transported to landfill should be performed according to the Guidelines for Acceptance of Solid Waste to Landfill (DEP, 2001), which provide guidance on the number of samples to be collected depending on the amount of material. Clean fill to be imported to the site should also be sampled in accordance with the Solid Waste Acceptance Guidelines for Landfill (DEP, 2001). The fill should be assessed against Ecological Investigation Levels (EILs) according to the Soil, Sediment and Water Assessment Levels (DEP, 2001).

SAMPLING OF SOILS IN VICINITY OF USTS

  • Factors to be Considered for Soil Sampling for the Investigation of USTs .1 Sample Location
  • Soil Sampling for the Investigation of UST Associated Infrastructure
  • Sample Depth for Sites Incorporating USTs

It should be noted that even if no contaminated soil is detected around the UST(s), the possibility of a leak from the UST(s) or associated infrastructure remains. Samples should be taken as close to the tank as possible and should extend to a depth below the bottom of the tank. Where fill material is present around the UST/infrastructure, samples should be taken from both the fill material and surrounding natural soils.

One sample is required from the base and one sample from each wall of the tank pit (after the backfill material has been removed). If a fill other than clean fill is used, samples of the fill material must be sampled to ensure that the fill material will not re-contaminate the site and meet the EIL. Samples should be as representative as possible and should not be collected from the surface of the stock (composite samples should not be collected when testing volatile or semi-volatile substances).

SEDIMENT SAMPLING DESIGN

INTRODUCTION AND OBJECTIVES

Once analytical results are received, identification of the severity of contamination should be made by comparison of site-specific investigation and response levels, or with the DEP accepted assessment levels as presented in the Assessment Levels for Soil, Sediment and Water (DEP, 2001) guideline.

SEDIMENT SAMPLING LOCATIONS .1 Pattern Types

  • Sampling Depth
  • Number of Samples
  • Frequency of Sampling

Where there is little or no data on the potential contamination of the area, then a systematic (grid) sampling design should be adopted. It is emphasized that the purpose of a SAP is to produce data which are an accurate representation of the in situ contamination at a site; therefore a sampling design must be applied in order to produce adequate information on the type, location and extent of any contamination. Pilot samples should be analyzed for the full range of chemical parameters expected to be present.

As with soil sampling programs, the number of samples is dependent on site history, distribution of contaminant sources, and migration pathways of contamination. Where contaminated sediments are located along a stream or riverbed, the depth and downstream extent of contamination must be identified. After remediation of contaminated sediments, ongoing monitoring may be required to ensure that recontamination of the sediments in the area does not occur (eg through contaminated water flowing over the site, or discharge from unknown or remote contamination sources).

GROUNDWATER SAMPLING DESIGN

  • INTRODUCTION AND OBJECTIVES
  • GROUNDWATER SAMPLING PROGRAM .1 Factors to be Considered
  • INSTALLATION OF GROUNDWATER MONITORING BORES
    • Selection of Bore Locations
    • Drilling
    • Bore Construction
    • Bore Development
    • Bore Completion
    • Documentation
  • GROUNDWATER SAMPLING
    • Groundwater Level Measurement
    • Purging
    • Frequency of Sampling

Soil samples must be collected, recorded and analyzed during the installation of the groundwater monitoring boreholes. The location and length of the shielded interval in groundwater monitoring wells can be critical. Bores must be made to ensure that the water table at the site is at a depth within trench spacing of the groundwater monitoring bore (often one meter of screen above the water table and at least two meters below).

The construction of groundwater monitoring pits will depend on the total depth of the aquifer. Groundwater monitoring holes for the detection of ADNPLs should be constructed so that the monitored interval extends to the entire depth of the aquifer or is located immediately above any impervious horizon that is identified. Combining borehole height with groundwater depth data enables the development of a groundwater contour diagram for the location and determination of local groundwater flow direction.

Table 4 provides a summary of minimum groundwater sampling requirements.
Table 4 provides a summary of minimum groundwater sampling requirements.

REMEDIATION, VALIDATION AND ONGOING MANAGEMENT

INTRODUCTION AND OBJECTIVES

It should be noted that where UST(s) have contained petroleum products, the removal, disposal and in situ abandonment of these tanks must be carried out in accordance with guidance S321 Removal and Disposal of Underground Petroleum Storage Tanks (DME, 1999). All product lines must be flushed and any residual products must be removed by an appropriate contractor before work begins to remove the USTs. The integrity of the pipeline (especially where connections occur) should be established by an approved person (see guidance S321) prior to removal of the UST.

It is also useful to provide photographic evidence of the condition of the tank sump after the UST has been removed. Removal of the tank would present significant risk to the structural integrity of nearby buildings or structures. A competent professional can demonstrate to DEP's satisfaction that the risks of contamination of surrounding soil and groundwater are acceptable.

VALIDATION SAMPLING PATTERN SELECTION .1 Remaining In Situ Soil

  • Remaining In Situ Sediment
  • Groundwater
  • Backfill Material
  • Remediated Material

Validation of sediment cleanup should be completed by systematic sampling of the remediated area (ie, a grid pattern including collection of samples along the perimeter of the remediated area and immediately beyond the remediated area) to verify that no dispersal of contaminated sediments has occurred . The number of samples required will depend on the size of the remediated area, any dispersal of sediment that occurred during cleanup activities, any movement of sediment into the remediated area, and the nature of the contaminants. Accurate validation of contaminated groundwater or of the improvement of groundwater quality is difficult due to inherent variability in groundwater quality and sampling and analysis errors.

Sampling must be completed in accordance with the inventory sampling guidelines provided in the Guidelines for Acceptance of Solid Waste to Landfill (DEP, 2001) and the results assessed against EILs according to Assessment Levels for Soil, Sediment and Water (DEP 2001). Where fill is obtained from a number of locations, documented evidence and/or analysis results are required for each fill source, along with a list of the volumes obtained from each source. Where fill is introduced, it usually becomes the surface material of the site, therefore confirmation of its quality is required to ensure minimal risk to human health and the environment.

GLOSSARY

Contaminant rebound Occurs when non-aqueous phase liquid (NAPL) residues, sorbed or otherwise immobilized contaminants, redissolve in the groundwater. Non-aqueous substances whose average density is greater than water (specific gravity greater than 1) and therefore tend to sink in water. Non-aqueous substances that have an average density less than water (specific gravity less than 1) and therefore usually float on water, e.g.

Differences in the physical and chemical properties of water and non-aqueous phase liquids (NAPLs) result in a physical interface between the liquids, which prevents mixing of the liquids. An area designated under the Metropolitan Water Supply and Drainage Act 1909 to protect groundwater resources used for public drinking water supplies. Water reserve An area designated under the Local Areas Water Supply Act 1947 to protect groundwater resources used for public drinking water supplies.

CITED REFERENCES

OTHER USEFUL REFERENCES

The health risk assessment and management of contaminated sites, Proceedings of a national workshop, South Australian Health Commission, Adelaide. 1994) Environmental Quality Objectives in the Netherlands – A Review of Environmental Quality Objectives and their Policy Framework in the Netherlands. Division of Risk Assessment and Environmental Quality, Directorate of Chemicals, External Safety and Radiation Protection, Ministry of Housing, Spatial Planning and the Environment, The Netherlands.

Proceedings of the first and second national workshops on the health risk assessment and management of contaminated sites. US Environmental Protection Agency (USEPA) (1986) Test Methods for the Evaluation of Solid Wastes – Physical/Chemical Methods SW-846 – 3rd edition (revised July 1992). Conference proceedings “Contaminated site remediation: challenges posed by urban and industrial contaminants”, Center for Groundwater Studies 1999.

APPENDIX A

APPENDIX A. SAMPLING PATTERNS

APPENDIX B

APPENDIX B. NUMBER OF SAMPLING LOCATIONS REQUIRED FOR HOT SPOT DETECTION

APPENDIX C

APPENDIX C. MINIMUM SAMPLING POINTS REQUIRED FOR SITE CHARACTERISATION BASED ON DETECTION OF CIRCULAR HOT

SPOTS USING SYSTEMATIC GRID SAMPLING PATTERN

APPENDIX D

APPENDIX E

APPENDIX E. BORE CONSTRUCTION DETAILS

APPENDIX F

TANK PIT VALIDATION: TYPICAL SOIL SAMPLING LOCATIONS

Figure

TABLE 1.  OVERVIEW OF SAMPLING REQUIREMENTS  8
TABLE 1.  OVERVIEW OF SAMPLING REQUIREMENTS
TABLE 2.  QUALITY CONTROL SAMPLES
Table 4 provides a summary of the minimum requirements for groundwater sampling.
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References

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