Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1850:p27
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1850 (pt 27/117)
Character Range: 421070–424485

and surface waters

    7.6.1          Leaching potential to groundwater and surface water
Contaminants in soil can leach to groundwater under certain conditions. For inorganic substances, leachability is particularly affected by soil pH, contaminant solubility and redox (Eh) conditions.

The leachability characteristics of contaminated soil can be used to help assess:
    * the impact of soluble soil contaminants on groundwater quality
    * the impact of leaving contaminated soil materials on site.

    7.6.2          Soil leaching tests
Information on leachability tests applicable to the assessment of site contamination can be found in Sections 2.7 and 12 of Schedule B3.
Samples to be tested should be selected with reference to the CSM and be representative of the impacted materials. Analysis of appropriate background samples should be included for comparative purposes.

    7.6.3          Theoretical calculation of porewater concentration
Methodologies are available which aim to predict the impact of leaching soil contaminants on groundwater quality and groundwater resources. An overview of the US EPA (1996) methodology is included in Schedule B5b.

    7.6.4          Disposal of contaminated soils
Treatment and disposal of excavated contaminated soils should be in accordance with jurisdictional legislation or guidelines for re-use and/or disposal of contaminated soils.

    8                   Groundwater assessment
The recommended risk–based approach to the assessment of groundwater contamination is outlined in Schedule B6.

The process involves a staged risk-based approach to delineation of contamination using guidelines such as the Australian and New Zealand guidelines for fresh and marine water quality (AWQG) (ANZECC & ARMCANZ 2000), the Australian drinking water guidelines (ADWG) (NHMRC 2011) and the Guidelines for managing risk in recreational water (GMRRW) (NHMRC 2008) as appropriate investigation and response levels. The process may include a detailed assessment of contaminant concentrations over time using fate and transport modelling to predict the current position and future movement of groundwater contaminants to assess potential risk to receptors.

This section deals with the basic requirements for groundwater investigation, including installation of monitoring wells, sampling of groundwater, presentation of data and delineation of groundwater contamination.

Fractured rock aquifers (for example, fractured basalts, bedrock aquifers and limestones) behave fundamentally differently from unconsolidated aquifers such as sands and gravels. Specialist advice should be sought from qualified contaminant hydrogeologists with experience in fractured rock aquifers. Further information on groundwater flow and groundwater sampling in fractured rock aquifers can be found in Cook (2003) and Nielsen (2006) and references therein. The US EPA CLU-IN website also provides useful information on characterising fractured rock aquifers and lists various related resources at: http://www.clu-in.org/contaminantfocus/default.focus/sec/Fractured_Rock/cat/Overview/.
Site assessors should be aware of (and comply with) relevant jurisdictional requirements such as groundwater protection policies and licensing requirements for the construction of monitoring bores and groundwater abstraction.

The collection and assessment of groundwater data and the selection and use