TRIAL IMPLEMENTATION OF HEALTH BASED TARGETS

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1 TRIAL IMPLEMENTATION OF HEALTH BASED TARGETS Marty Hancock Treatment Plant & Catchment Engineer

2 ADWG Guiding Principle 1 The greatest risks to consumers of drinking water are pathogenic microorganisms. Protection of water sources and treatment are of paramount importance and must never be compromised.

3 Don t the ADWG already provide the guidelines (targets) for drinking water? Values for hazardous chemicals No targets for pathogenic micro-organisms Disinfection and turbidity targets E.coli should be absent from drinking water But much of the disease risk comes from other pathogens

4 What are HBTs? Benchmark that defines the pathogenic level of risk that is acceptable. Absolute values are difficult for pathogens Can t measure online Temporal variation in presence What level is safe? Infectivity varies greatly

5 What should the target be? Internationally HBTs used for microbial safety Based on risks of illness or infection NHMRC (2014) released a discussion paper on the implementation of these HBTs Proposed two definitions for microbial safety 1. WHO Disability-adjusted life years (DALY) Target 1 µdaly pppy 2. USEPA - Infection rate Target 1 infection per 10,000 people per year

6 What is a DALY? A measure of the impacts of disease in terms of loss of good health

7 What is a DALY? WHO target is 1 µ (10-6 )DALY pppy or 1 DALY per million ppy Concentration of a pathogen in treated water should be such that the health impact is < 1 µdaly pppy To determine the treatment requirements the severity of symptoms for each pathogen needs to be calculated (DALY/case)

8 What is a DALY? DALYs calculated by weighting each health impact in terms of severity and multiplying this by how long it lasts and the frequency of occurrence in cases. eg.cryptosporidium 1.7 DALY/1000 cases or 1.7x10-3 DALY/case (based incidence and severity of disease)

9 What is a DALY? The 1 µ DALY target can be translated into illness rates Given the burden of disease for each case of crypto is 1.7 x 10-3 DALYs 1 DALY per 10 6 ppy = 1/1.7x10-3 = 590 cases of crypto per million people The number of cases can be related to the pathogen exposure and an acceptable pathogen removal level determined. The pathogen removal requirements are then related to treatment processes

10 HBT Manual WSAA formed a working group that developed a manual for the trial implementation of HBTs Tweed Shire Council participated in 2014 Manual uses the WHO 1 µdaly HBT Process is consistent with ADWG framework

11 Water Safety Continuum

12 Water Safety Assessment Process (WSAA 2014)

13 Assessment Process 1. Tier 1 Source water assessment Sanitary Survey Tier 1 is a binning system groups the risk and assigns a conservative LRV Tier 2 is optional and requires protozoan data followed by a Quantitative Microbial Risk Assessment) 2. Vulnerability Assessment (4 categories): protected, moderately protected, poorly protected or unprotected catchment 3. Microbial Indicator Assessment confirm vulnerability 4. Water Safety Assessment compare actual LRV with required LRV 5. Water Safety Continuum 6. Water Safety Improvement Plan

14 Tweed Water Supply

15 Sanitary Survey Tier 1 A source water assessment was previously completed for DWMS but did not meet the requirements of a Sanitary Survey which is focused on pathogen sources.

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18 Sanitary Survey Bray Park Supply Main land uses Broad scale grazing approx. 30% Privately owned bushland approx. 30% National Park approx. 30% Main sources of pollution 2 dairies and 1 piggery Wildlife Broad scale grazing with access to waterways Onsite sewage management systems (approx. 830) Itinerant human activities

19 Vulnerability assessment Bar Park Supply Category 4 - Unprotected Catchment HBT manual definition: sources have high levels of faecal contamination from human and agricultural activities. The inner catchment is not protected and recreation may occur throughout the catchment and on the water body.

20 Vulnerability assessment Uki Supply Category 3 Poorly protected Catchment No dairies, piggeries, villages or WWTP Tyalgum Supply Category 4 Unprotected Catchment

21 Microbial Indicator Assessment Source water vulnerability assessment category 20 Typical of category 1 sources Microbial indicator concentration category Maximum E. coli (#) per 100 ml > 20 2,000 > 2,000 20,000 Typical of Typical of category 2 and 3 sources category 4 sources > 20,000 Not suitable as a drinking water source without a high level of treatment 1 Source = Cat 1 Source = Cat 2 Anomalous Not suitable 2 Source = Cat 2 Source = Cat 2 Anomalous Not suitable 3 Anomalous Source = Cat 3 Source = Cat 4 Not suitable 4 Anomalous Source = Cat 4 Source = Cat 4 Not suitable Bray Park water supply had a maximum of 9208 E. coli and confirms Category 4 Uki water supply had a maximum of 9404 E. coli which does not support Category 3 Tyalgum water supply had a maximum of E. coli which is anomalous with the Category 4

22 Minimum pathogen reduction requirements Source water category Minimum pathogen log reduction required Bacteria Viruses Protozoa These requirements were derived from international sources and work completed by the HBT project team (see manual Appendix B)

23 Water Treatment assessment Bray Park WTP Pre-treatment Coagulation/Flocculation Alum Membrane Ultrafiltration Chlorine disinfection

24 Pre-treatment Coagulation ACH Membrane Ultrafiltration GAC Filters Chlorine disinfection Tyalgum WTP

25 Pre-treatment Coagulation/Flocculation Alum Membrane Ultrafiltration Chlorine disinfection Uki WTP

26 Comparison of required and achieved LRV Category 4 requirement Log Reduction Value Protozoa Bacteria Virus Bray Park WTP Ultrafiltration >4 3 2 Chlorination Total >4 7 6 Shortfall < Uki WTP Conventional (Dyna sand) Chlorination Total Shortfall Tyalgum WTP Ultrafiltration >4 4 2 Chlorination Total >4 8 6 Shortfall <

27 Water safety assessment and continuum Treatment adequate to meet the one µdaly target for bacteria and viruses but not for protozoans. Bray Park and Tyalgum WTP's - SAFE (0.5-1 LRV shortfall) No danger of an imminent public health incident.

28 Water safety assessment and continuum Uki WTP - MARGINAL ( LRV shortfall) Public health incident is still unlikely but there is no buffer should the source experience an unusually high challenge or the WTP performance deteriorates.

29 Improvement Plan Catchment Management Strategy to identify pathogen sources and target actions Tier 2 assessment of the catchment to verify the Category 4? Review DWMS Critical Control Points Improve online monitoring and records Improve Uki WTP turbidity Treatment process improvements - UV

30 Conclusions The WSAA HBT Manual is a useful tool for the introduction of HBTs Process data and accuracy were not sufficient to verify the process critical limits HBT shortfall for Uki with old media process no surprise HBT shortfall for Bray Park and Tyalgum with ultrafiltration unexpected

31 Conclusions Bray Park was commissioned in 2010 at a cost of $75m and Tyalgum in 2013 at a cost of $1.4m. Management is surprised to lean that neither meet HBT targets for protozoans and will require additional processes! UV is the most likely addition required HBT trial will drive changes to CCP s and improvements with existing processes in the short term.

32 Where to from here? Given WTPs in the SAFE part of continuum Council will wait to see what happens to HBTs and changes to ADWG before making significant process changes Implement Catchment improvements Implement treatment improvements that don t require additional processes Implement changes to CCP s and record keeping