CONTAMINATED WATER GETTING INTO THE BORE/WELL FROM THE SURFACE cont’d P1.3.4.4 Consider elevation of Ensure site is bore/well head when well drained to Bore/well sited siting bore/well. pooling of in low ground. water. P1.3.4.5 Ensure bore is equipped with backflow prevention. Event: CONTAMINATION OF THE AQUIFER (the source) Possible hazards: Germs and chemical determinands appropriate to contamination sources. Level of risk: High P1.3.5.1 Identify potential No survey of Add treatment sources of quality. potential processes to Contamination contamination when sources of remove sources (eg, Chemical well is sited (see contamination identified stock, septic determinands Guide S1.1). undertaken. contaminants. tanks, appropriate chemical Ensure that changes for likely No aquifer Instigate sources) too in land use (including contamination tests carried system for close to the urban developments) source. out. gathering bore/well and the potential for information No system for head, or contamination they about land use obtaining bore/well too create, are well changes. information shallow. monitored after about construction of the changing land bore/ well. use in place. Restrict activities in the aquifer recharge zone that may contaminate the water (see Guide S1.1). Gather information about the vulnerability of the aquifer before undertaking development. P1.3.5.2 Assess the security Isotope and Tests to Take actions status of the aquifer CFC demonstrate to reduce Aquifer is not before undertaking determinands, security do not possible secure. development so that and/or meet the contamination treatment needs can requirements sources. Conductivity be identified, and the of Ensure Chloride importance of DWSNZ:2000. treatment restrictions on Nitrate Changes in processes are activities in the turbidity in place to (See DWSNZ:2000 recharge zone and/or colour compensate Section 3.2.4.) evaluated (see of water with for unsecure DWSNZ:2000 Section weather source. 3.2.4). conditions. Event: TOO LITTLE WATER CAN BE DRAWN FROM THE BORE OR WELL TO MEET DEMAND Possible hazards: Germs and chemicals that get into the water because of low system pressure; hazards associated with poor hygiene. Level of risk: High1
CONTAMINATED WATER GETTING INTO THE BORE/WELL FROM THE SURFACE cont’d P1.3.4.4 Bore/well sited in low ground. Consider elevation of bore/well head when siting bore/well. Ensure site is well drained to pooling of water. P1.3.4.5 Ensure bore is equipped with backflow prevention. Event: CONTAMINATION OF THE AQUIFER (the source) Possible hazards: Germs and chemical determinands appropriate to contamination sources. Level of risk: High P1.3.5.1 Contamination sources (eg, stock, septic tanks, chemical sources) too close to the bore/well head, or bore/well too shallow. Identify potential sources of contamination when well is sited (see Guide S1.1). Ensure that changes in land use (including urban developments) and the potential for contamination they create, are well monitored after construction of the bore/ well. Restrict activities in the aquifer recharge zone that may contaminate the water (see Guide S1.1). Gather information about the vulnerability of the aquifer before undertaking development. quality. Chemical determinands appropriate for likely contamination source. No survey of potential sources of contamination undertaken. No aquifer tests carried out. No system for obtaining information about changing land use in place. Add treatment processes to remove identified contaminants. Instigate system for gathering information about land use changes. P1.3.5.2 Aquifer is not secure. Assess the security status of the aquifer before undertaking development so that treatment needs can be identified, and the importance of restrictions on activities in the recharge zone evaluated (see DWSNZ:2000 Section 3.2.4). Isotope and CFC determinands, and/or Conductivity Chloride Nitrate (See DWSNZ:2000 Section 3.2.4.) Tests to demonstrate security do not meet the requirements of DWSNZ:2000. Changes in turbidity and/or colour of water with weather conditions. Take actions to reduce possible contamination sources. Ensure treatment processes are in place to compensate for unsecure source. Event: TOO LITTLE WATER CAN BE DRAWN FROM THE BORE OR WELL TO MEET DEMAND Possible hazards: Germs and chemicals that get into the water because of low system pressure; hazards associated with poor hygiene. Level of risk: High1