Planning Information Evening

1. Planning Information Evening Rural Housing Wastewater Treatment & Disposal Amber Springs Hotel, Gorey, 29th October 2008 Brendan Cooney B.Sc., Dip.Sc., M.Sc. Senior Executive Scientist. Environment Section Wexford County Council

2. EPA Environment in Focus • 57% of all groundwater samples taken by the EPA showed faecal contamination (E. coli) & 25%exceeded guideline nitrate values • The two most likely causes of faecal contamination are land spreading of animal manures and poorly sited wastewater treatment systems

3. Conventional Septic Tank System

4. Effluent Discharged to Groundwater

5. Effluent Quality from a Typical Dwelling • Single house approx. 250,000 l/year (70,000 gals/year) • >1 million faecal bacteria/100 ml + viruses + cryptosporidium • BOD 300 mg/l • Total Nitrogen 50 mg/l (as N) • Total Phosphorous 10 mg/l (as P) • Plus various chemicals used in the home!

6. What are the Risks Associated with On-site Effluent Treatment Systems? • Effluent Ponding - Public health hazard (inadequate percolation) • Surface water contamination – Public health & environmental hazard • Groundwater contamination – Public health hazard (Drinking Water Contamination) • Density of systems – Greater the density the greater the risk • Backing up of sewage in drains (inadequate percolation and/or poor construction) • Fly and odour nuisance • All of these are public health issues as well as environmental pollution problems!

7. What is Required as Part of a Planning Application for a Single House? • Site Suitability Assessment carried out in accordance with EPA Manual by a Registered Agent. If the site proves suitable for on-site discharge to ground – NO FURTHER REQUIREMENT • The EPA site characterisation form provides the assessor and Local Authority with a standard assessment framework to allow a decision to be made on the appropriate method of wastewater treatment for a site • Two key questions the assessor must answer via the assessment: • Attenuation – can I adequately treat the wastewater? • Hydraulics – can I safely discharge the quantity of treated wastewater generated, to ground or surface water?

8. Site Characterisation Form • Desk Study • On site assessment (a) Visual Assessment (b) Trial Hole (c) Percolation Tests • Conclusion & Recommendation • Site Suitable – Selection of appropriate system and disposal route, or • Site Unsuitable – Development not permitted for reasons of Public and Environmental Safety

9. T and P Tests • T Test: • Taken at the level of the discharged effluent – about 1m below ground level • Value reflects average time taken for water to drop 1 inch • Appropriate T values are between 1 and 50 (indicates adequate “soakage”) • P Test: • Taken at the upper level of the ground for soil that may be used to construct a percolation area • Appropriate P values are also between 1 and 50 • Used where T value is <1 (too fast) or T value between 50 and 90 (relatively slow)

10. Trial Hole

11. Percolation Test Hole

12. Failed Trial Hole (high water table)

13. Failed Percolation Test (high water table)

14. When are Advanced Systems an Option? • In cases where a site is deemed unsuitable for a conventional septic tank system and further effluent treatment is necessary: • Where T value has been determined to be between 50 and 90 and the P value has been determined to be between 1 and 50 • Recommended in shallow rock areas (less than 2.0m) • In the inner protection zone of public supply wells where the vulnerability is deemed extreme • It is relatively less demanding of the soil/subsoil than conventional septic tank system

15. Typical Treated Effluent Quality • Septic Tanks achieve 30 – 40% reduction in BOD/TSS levels • Advanced Treatment Systems achieve 93% reduction in BOD/TSS levels • Treated effluent is not drinkable! • Treating effluent still has pollution power and requires dilution • Treated effluent will smell and form a green scum if left lying in a dry dyke/ditch • Treated effluent contains harmful pathogens (bacteria, viruses, etc.) and household chemicals

16. What if My Site Fails the Site Suitability Test? • Failure occurs where the site is hydraulically unsuitable: • inadequate percolation (T value >90) • and/or high water table and effluent cannot migrate from the site and will pond • An Advanced Treatment System will not solve this problem • Discharge to a suitablewatercourse may be permitted

17. Looks like a Good Site!

18. Obviously Passed the Site Test!

19. Discharge of Treated Effluent Off-Site to Surface Waters • In order to determine whether or not a river or stream is suitable for receiving treated effluent the following is required: • Flow Measurement • Chemical Samples & Biological Rating • Calculations & Report (Assimilative Capacity) • Discharge permitted if no significant environmental damage caused • Discharge requires a licence in accordance with Water Pollution Act, 1977 & 1990

20. Taking a Flow Measurement

21. Assimilative Capacity Effluent Load Combined Quality Upstream Quality

22. Unsuitable Watercourses • Watercourses that run dry • The extreme headwaters of a catchment (<500m from source or <1km2 catchment) • Waters with inadequate dilution (assimilative capacity) • Where the waters are moderately or seriously polluted as indicated by the Q Value Wexford County Council are prohibited by law from issuing a licence under Section 4 (4) where a discharge of an effluent would result in a water quality standard being breached

23. Even Rivers Dry Up!

24. Key Questions • How do I know if my site is suitable for on-site wastewater disposal via percolation? • EPA Site Suitability Report performed by Registered Agent • What if I don’t have adequate percolation on-site? • It may be possible to discharge to a suitable watercourse in accordance with a WPA Discharge Licence but the watercourse must be assessed to demonstrate that no Public Health or Environmental problems would occur • Is it safe to assume that some form of advance treatment system can address each and every site situation? • No – advanced systems are not the panacea for all cases. You must be able to dispose of your treated effluent safely to either groundwater or surface water

25. Wexford County Council Guidelines • Wexford County Council Guidelines for Water Pollution Licensing and Discharge of Effluent to Waters available on Council website: • www.wexford.ie • Environment • Water Quality & Licensing

26. Thank You Go raibh maith agaibh