Preventive measures Checking preventive measures Corrective action Causes What to check Signs that action is needed SOURCE WATER RECEIVES SEPTIC TANK DISCHARGES Possible hazards: Germs; chemical determinands (predominantly nitrate and nitrite). Level of risk: High S1.1.7 Develop an understanding of E. coli in raw Median E. coli Get more the extent of the source water (12 over information Septic tanks within catchment or recharge zone. consecutive 12 months is about the source Identify source protection monthly more than catchment or protection zone Zones I, II and III. samples). 500/100ml. recharge zone. (see S1.1.2). Obtain information about the Nitrate. Elevated Approach number and location of septic levels of council for Nitrite. tank discharges in the nitrate, nitrite information catchment or recharge zone. in source concerning discharge Liaise with councils to identify consents for all septic tank disposal fields Reticulated septic tanks in located within source water not the area. protection Zone II. compliant with DWSNZ: Establish Request that the council 2000. strategy to deal decline new applications for with the effects septic tank installation within Lack of of any septic source protection Zone II. knowledge of tanks that are catchment/ Once the location of septic affecting the recharge tank discharges are known, source. zone, and establish a strategy to: sources of Consider monitor water quality for treatment evidence of in the area. options contaminants1 (particularly No develop a plan with the disinfection – information council monitoring see P7 Guide to and site inspection to series) or provide of development of ‘early-warning’ of source contamination a new source. satisfactory in collaboration with separation councils, provide public between information on bores/wells recommended and tanks. maintenance and use of septic tank systems identify and carry out measures that can be put in place to control contamination from the existing discharges. 1 The monitoring plan should take into account seasonal changes, as lower flows can lead to higher contaminant concentrations. Situations in which contamination is most likely to occur should be identified so that monitoring can be suitably timed. Preventive measures Checking preventive measures Corrective action Causes What to check Signs that action is needed Event: SOURCE WATER RECEIVES RUN-OFF FROM URBAN OR SEALED SURFACES Possible hazards: chemical determinands. of risk: Moderate-high
Causes Preventive measures Checking preventive measures Corrective action What to check Signs that action is needed SOURCE WATER RECEIVES SEPTIC TANK DISCHARGES Possible hazards: Germs; chemical determinands (predominantly nitrate and nitrite). Level of risk: High S1.1.7 Septic tanks within the source protection zone (see S1.1.2). Develop an understanding of the extent of the source catchment or recharge zone. Identify source protection Zones I, II and III. Obtain information about the number and location of septic tank discharges in the catchment or recharge zone. Liaise with councils to identify all septic tank disposal fields located within source protection Zone II. Request that the council decline new applications for septic tank installation within source protection Zone II. Once the location of septic tank discharges are known, establish a strategy to: monitor water quality for evidence of contaminants1 develop a plan with the council monitoring and site inspection to provide ‘early-warning’ of source contamination in collaboration with councils, provide public information on recommended maintenance and use of septic tank systems identify and carry out measures that can be put in place to control contamination from the existing discharges. E. coli in raw water (12 consecutive monthly samples). Nitrate. Nitrite. Median E. coli over 12 months is more than 500/100ml. Elevated levels of nitrate, nitrite in source Reticulated water not compliant with DWSNZ: 2000. Lack of knowledge of catchment/ recharge zone, and sources of in the area. No information to of satisfactory separation between bores/wells and tanks. Get more information about catchment or recharge zone. Approach council for information concerning discharge consents for septic tanks in the area. Establish strategy to deal with the effects of any septic tanks that are affecting the source. Consider treatment options (particularly disinfection – see P7 Guide series) or development of a new source. 1 The monitoring plan should take into account seasonal changes, as lower flows can lead to higher contaminant concentrations. Situations in which contamination is most likely to occur should be identified so that monitoring can be suitably timed. Causes Preventive measures Checking preventive measures Corrective action What to check Signs that action is needed Event: SOURCE WATER RECEIVES RUN-OFF FROM URBAN OR SEALED SURFACES Possible hazards: chemical determinands. of risk: Moderate-high
source-surface-ground-water-sources-feb14-v2.docx