Table 5.14 Criteria, controls and monitoring to mitigate pressure, flow or volume-related hazards in unconfined aquifers in relation to the stages of risk assessment rate is restricted intended to avoid causing a uses of recovered water drowning hazard or excessive Residual risk assessment Acceptance scouring (operational) criteria Maximal and Confirmation of • Entry-level or precommissioning achievement of simplified residual risk precommissioning assessment assessment residual risk assessment Groundwater criteria, based on • Infiltration model is • additional field and site is not calibrated laboratory measurements on sloping based on and validated groundwater land, adequate model adjacent to data Trials and modelling • surface Field data on soil reveal no adverse • profile down to effects on other or the aquifer, aquifers, connected aquifer properties water bodies or and calibrated ecosystems groundwater dependent modelling ecosystem show that the or predicted underlain by known shallowest shallow depth of watertable, layers outside the At basin or • gallery, is sufficient to site, not cause depth waterlogging – to watertable soil salinisation – exceeds 8 salt-damp – m in an foundation – urban area movement or 4 m in a structural damage – rural area flooding of with no – cellars or other nearby infrastructure Aquifer’s • capacity can • store volume intended, site is not in meeting criteria or above adjacent Existing land • to a uses and waste landfill or management in the known area have low risk of contaminating site groundwater and Reservoir • release inhibiting
Table 5.14 Criteria, controls and monitoring to mitigate pressure, flow or volume-related hazards in unconfined aquifers in relation to the stages of risk assessment Acceptance criteria Entry-level or simplified assessment • Infiltration site is not on sloping land, adjacent to surface or dependent or underlain by known shallow layers • At site, depth to watertable exceeds 8 m in an urban area or 4 m in a rural area with no nearby • site is not in or adjacent to a landfill or known site • Reservoir release rate is restricted to avoid causing a drowning hazard or excessive scouring Maximal and precommissioning residual risk assessment • Groundwater model is calibrated based on adequate data • Field data on soil profile down to the aquifer, aquifer properties and calibrated groundwater modelling show that the predicted shallowest depth of watertable, outside the basin or gallery, is sufficient to not cause – waterlogging – soil salinisation – salt-damp – foundation movement – structural damage – flooding of cellars or other infrastructure • Aquifer’s capacity can store volume intended, meeting criteria above • Existing land uses and waste management in the area have low risk of contaminating groundwater and inhibiting intended uses of recovered water Residual risk assessment (operational) • Confirmation of achievement of precommissioning residual risk assessment criteria, based on additional field and laboratory measurements and validated groundwater model • Trials and modelling reveal no adverse effects on other aquifers, connected water bodies or ecosystems ecosystem
water-recycling-guidelines-mar-24.docx